Tesi: "Shoot regeneration"

1

Kanakis, Andreas G. "In vitro plant regeneration studies with Capsicum annuum". Thesis, University of Bath, 1987. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380371.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

2

Boul, H. Lawrence. "A study of shoot regeneration in leaf disc cultures of two solanaceous plants". Thesis, University of Canterbury. Botany, 1992. http://hdl.handle.net/10092/5678.

Testo completo

Abstract (sommario):

The behaviour of Solanum laciniatum and "Mitchell" Petunia leaf discs in culture was examined. In both systems shoots were formed in response to an appropriate auxin/cytokinin balance via a caulogenic pathway involving the epidermal tissues with no intermediate callus. Petunia explants could also be induced to form roots, which were found to have an endogenous origin quite different to that observed for shoots. The shoot inducing hormone balance was found to be required for only a short window in the shoot formation timecourse. The hormone balance required to make explants competent for shoot initiation, was less specific than that required for them to become determined for shoot development. Development itself would occur on a medium devoid of growth regulators. The effect of culturing explants on ungelled medium was also examined. The number of shoots initiated was dramatically increased over those on agar gelled media for both species. Liquid cultured Petunia explants showed an increase in both the number of shoots developing per explant and the rate of development. The effects of a number of reagents on shoot formation from Solanum laciniatum and Petunia explants was examined as was the effect of the nitrogen source on Petunia explants. The response of explants of both species to 2,3,5 triiodobenzoic acid (TIBA) , ribose, sorbitol and acetylsalicylic acid (ASA) was similar although the sensitivities varied. TIBA was found to promote shoot formation at low concentrations, but inhibit it at higher levels. Ribose, sorbitol and ASA inhibited shoot formation from explants of both species, and partial substitution of Murashige and Skoog nitrogen with NH4Cl inhibited shoot formation from explants of Petunia. Changes in gene expression accompanying shoot, root and callus production in Petunia explants were monitored by two dimensional polyacrylamide gel electrophoresis of both total extractable protein, and labelled newly synthesised proteins (for shoot and callus forming cultures). In addition the protein profiles of shoot forming cultures inhibited with ASA, TIBA and NH4Cl were also examined. A single silver stainable protein specific to shoot forming cultures, and 4 proteins specific to root formation were discovered. In general, protein changes in the first 4 days of culture greatly exceeded subsequent changes for all three culture systems. The patterns of proteins observed from explants cultured on the three inhibitors were similar. The inhibitors did not prevent the formation of the shoot specific protein, but did result in other changes in protein profile. The most significant of these was the occurrence of a labelled protein which was also found to occur in the nonshoot-forming central portion of uninhibited explants.

Gli stili APA, Harvard, Vancouver, ISO e altri

3

Barretto, Sherwin Savio. "Tobacco shoot regeneration from calli in temporary immersion culture for biosynthesis of heterologous biopharmaceuticals". Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/44957.

Testo completo

Abstract (sommario):

‘Molecular farming’, the use of transgenic plants to produce biopharmaceutical proteins is emerging as a new biotechnological paradigm. Transgenic plants offer several advantages over conventional microbial and mammalian cell host technologies. In particular, transplastomic plants, with transformed plastid genomes, are capable of massive expression of foreign proteins and represent a promising platform for biopharmaceutical synthesis. The main theme of this PhD thesis is the investigation of in vitro regeneration of tobacco (Nicotiana tabacum) shoots from callus tissue in temporary immersion (TI) culture for heterologous biopharmaceutical synthesis. There is special emphasis on subunit vaccine expression in transplastomic tobacco, in which foreign protein accumulation is correlated with chloroplast number and development during the organogenesis process. Studies using transplastomic N. tabacum expressing TetC (tetanus toxin fragment C) investigated the influence of several culture parameters on biomass regeneration and recombinant protein expression. The parameters investigated include medium nitrogen source ratio, sucrose concentration and hydrodynamics. These studies highlight the sensitivity of transplastomic protein yields to the culture microenvironment, and provide a starting point for further optimisation. Further studies demonstrated the feasibility of TI culture for biosynthesis of proteolytically-unstable transplastomic subunit vaccines, p24 (HIV antigen) and VP6 (rotavirus antigen). TI culture is also demonstrated as a means for nuclear expression of functional Guy’s 13 monoclonal antibody. Finally, the use of TI culture as the basis of novel technological innovations is investigated. This includes the demonstration of transplastomic protein expression in a prototype large-scale mechanical temporary immersion bioreactor. Encapsulation of callus aggregates in an alginate matrix for long-term germplasm preservation was trialled, prior to temporary immersion regeneration. Overall, this work presents a novel in vitro propagation method for the contained large-scale biosynthesis of biopharmaceutical proteins, as a potential alternative to conventional plant propagation platforms based on agricultural cultivation or cell suspension culture.

Gli stili APA, Harvard, Vancouver, ISO e altri

4

Craig, Jared Matthew. "EFFECTS OF MIDSTORY REMOVAL AND SHOOT CLIPPING ON THE GROWTH AND DEVELOPMENT OF THREE OAK SPECIES". UKnowledge, 2012. http://uknowledge.uky.edu/forestry_etds/9.

Testo completo

Abstract (sommario):

Problems developing tall oak seedlings of high abundance have become a concern throughout many eastern hardwood forests. The decline in oak seedling recruitment into canopy positions is often attributed to the increasing abundance of shade tolerant midstory species, especially red maple (Acer rubrum L.). Studies have shown that increasing light to the understory by way of a midstory removal has the ability to favor oak seedlings over competitors. The majority of studies to date have examined northern red (Quercus rubra L.) and cherrybark oak (Quercus pagoda Raf.) on productive sites, but relatively little is known about the effects of midstory removal on white (Quercus alba L.) and black (Quercus velutina L.) oaks, which are valuable species commercially and for wildlife. This study tests the effect of a midstory removal on oak seedlings and red maples six years after treatment implementation. In addition to seedling growth, survival, and competitiveness, the study also illustrates the changes in canopy structure and light transmittance resulting from the midstory removal. Basal clipping response of white oak seedlings following six years under a midstory removal is also examined as a method for regenerating more vigorous oaks. Results from this study support implementation of midstory removal as a method for improving oak regeneration.

Gli stili APA, Harvard, Vancouver, ISO e altri

5

Baloglu, Cengiz Mehmet. "Optimization Of Regeneration And Agrobacterium Mediated Transformation Of Sugar Beet (beta Vulgaris L.)". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12606476/index.pdf.

Testo completo

Abstract (sommario):

In this study, optimization of a transformation and regeneration system via indirect and direct organogenesis in cotyledon, hypocotyl, petiole, leaf and shoot base tissues of sugar beet (Beta vulgaris L. cv. ELK 345 and 1195) was investigated. Two different germination, three different callus induction and shoot induction medium was used for indirect organogenesis of sugar beet cultivar ELK 345. Except cotyledon, other explants (hypocotyl, petiole and leaf) produced callus. However no shoot development was observed from callus of these explants. Shoot base tissue of sugar beet cultivar 1195 was employed for direct organogenesis. Shoot development was achieved via direct organogenesis using 0.1 mg/L IBA and 0.25 mg/L BA. Root development and high acclimatization rate were accomplished from shoot base tissue. Different concentrations of kanamycin and PPT were applied to leaf blade explants to find out optimum dose for selection of transformants. Kanamycin at 150 mg/L and PPT at 3 mg/L totally inhibited shoot development from leaf blades. Moreover, an Agrobacterium mediated transformation procedure for leaf explants of ELK 345 was also optimized by monitoring transient uidA expression 3rd days after transformation. Effects of different parameters (vacuum infiltration, bacterial growth medium, inoculation time with bacteria, Agrobacterium strains and L-cysteine application in co-cultivation medium) were investigated to improve transformation procedure. Vacuum infiltration and Agrobacterium strains were significantly improved transformation procedure. Percentage of GUS expressing areas on leaves increased three folds from the beginning of the study.

Gli stili APA, Harvard, Vancouver, ISO e altri

6

Kocer, Zeynep Ahsen. "In Vitro Induction Of Growth And Development Of Common Juniper (juniperus Communis L.) From Shoot And Bud Explants". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12605891/index.pdf.

Testo completo

Abstract (sommario):

The objective of the study was to investigate the optimum conditions for in vitro regeneration of common juniper (Juniperus communis L.) by using indirect organogenesis approach. Throughout the study
callus induction, organogenesis, improved organogenesis and root induction experiments were performed sequentially. It was found that explant position, genotype, gender, treatments and sampling time had significant effects on callus induction rate in common juniper. The results of treatments indicated that IBA (indole-3-butyric acid) at concentration range 0.5-4.0 mg/l combined with MS medium supplemented with 0.1 mg/l BAP (benzylaminopurine), 3 % sucrose and 0.7% agar was the best one among the treatments to induce callus formation from common juniper explants collected as Spring buds. Also, a two-month culture was adequate period for the callus induction of common juniper regardless of position, before transferring the explants into organogenesis media. After a two-month culture in callus induction media, explants were transferred to organogenesis treatments in order to investigate adventitious bud development from callus tissues. There were significant differences among genotypes, treatments and explant-sampling times in initiation of organ development in common juniper. Additionally, it was found that excluding the auxin components while maintaining 1.0-2.0 mg/l BAP concentration in culture media, as refreshing after a month, stimulated the formation and development of adventitious buds and shoots. Among the treatments tested, it was found that 1.0 mg/l BAP plus 0.5 mg/l 2,4-D was the optimum culture media with adventitious bud formation capacity of 37.5% was though ageing of callus significantly affected the frequency of adventitious bud formation. Finally, rooting experiments were performed to investigate rooting efficiency of adventitious shoots. In the adventitious rooting experiments, no rooting was observed in any of the treatments used with common juniper explants. Although whole plantlet development from callus tissues could not be achieved as indirect organogenesis, the results of the study could aid to future studies dealing in vitro regeneration and production of secondary chemicals from common juniper.

Gli stili APA, Harvard, Vancouver, ISO e altri

7

Notini, Marcela Morato. "Understanding hormonal and temporal factors associated with tomato (Solanum lycopersicum L. cv. Micro-Tom) acquisition of competence: key concepts for in vitro shoot regeneration". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/11/11144/tde-07032018-132615/.

Testo completo

Abstract (sommario):

Plant regeneration through de novo organogenesis is a critical step in most of the plant micropropagation and genetic transformation procedures. In the last years, significant progress has been made in the understanding of the mechanisms underlying de novo organogenesis in the worldwide crop tomato (Solanum lycopersicum). However, the hormonal and molecular factors involving the acquisition of competence for tomato shoot formation, an essential step for the regeneration process, are still not known. The failure in acquire competence can be the reason for the widely described absence of shoot regeneration from tomato root explants. In the first chapter, we conducted a temporal and hormonal characterization of the tomato acquisition of competence and the shoot induction phases using the model system cv. Micro-Tom. Regeneration was improved by pre-incubation on root-inducing medium (RIM) during the early two days in culture, a period corresponding to acquisition of competence step in cotyledon explants. Conversely, the pre-incubation on another auxin-rich condition, the callus-inducing medium (CIM), under the same period, abolished the regeneration achievement. The 2d RIM pre-treatment induced an extensive and intense endogenous auxin response in the explant, probably improving the cells competence to produce shoots under further cytokinin induction on shoot-inducing medium (SIM). This knowledge was applied to improve the Agrobacterium-mediated tomato genetic transformation procedure, leading to an efficient, simple, inexpensive and genotype-independent protocol. In the second chapter, we developed an unprecedented method for tomato shoot regeneration from root explants. The shoot organogenesis was obtained by adjusting the CIM pre-treatment to the acquisition of competence period, corresponding to the initial four days in culture for root explants. The number and quality of shoots formed were also augmented by the optimization of explants properties, medium components, and culture conditions. Taken the two chapters together, the knowledge obtained about organogenic competence advanced and created new regeneration and genetic transformation systems, which are very useful tools for biotechnology and functional studies of specific genes in tomato.
A regeneração de plantas através da organogênese de novo é uma fase crítica para a maioria dos procedimentos de micropropagação e transformação genética. Recentemente, progressos significativos tem sido alcançados no entendimento dos mecanismos fundamentais à organogênese de novo de tomateiro (Solanum lycopersicum). Entretanto, fatores hormonais e moleculares envolvidos na aquisição de competência para formação de gemas caulinares na espécie, etapa essencial ao processo de regeneração, permancece desconhecido. O fracasso em adquirir competência pode ser associado a amplamente descrita incapacidade de tomateiro em regenerar brotos caulinares a partir de raízes. No primeiro capítulo, realizou-se uma caracterização temporal e hormonal das fases de aquisição de competência e indução de gemas caulinares usando a cultivar modelo Micro-Tom. A eficiência de regeneração foi melhorada através de pré-incubação em meio indutor de raízes (RIM) durante os dois primeiros dias de cultivo, período correspondente à fase de aquisição de competência em explantes cotiledonares. Diferentemente, a pré-incubação em outro meio rico em auxina, o meio indutor de calo (CIM), sob mesmo intervalo, aboliu completamente a regeneração. A pré-incubação de dois dias em RIM induziu uma intensa e extensa resposta a auxina endógena no explante, o que provavelmente aumentou a competência das células a induzir brotos caulinares em resposta a citocinina presente no meio indutor de gemas caulinares (SIM). A aplicação desse conhecimento na melhoria do procedimento de transformação genética via Agrobacteria levou a um eficiente, simples, barato e genótipo-independente protocolo. No segundo capítulo, nós desenvolvemos um método inédito de regeneração de tomateiro via explante radicular. A formação de brotos caulinares foi obtida por ajuste do pré-tratamento em CIM ao período de aquisição de competência, correspondente a quatro dias de cultivo em explantes radiculares. O número e qualidade dos brotos também foram elevados pela otimização do explante, composição do meio de cultivo, e condições de cultivo. Somando-se os dois capítulos, o conhecimento obtido a cerca da competência organogênica resultou em novos sistemas de regeneração e transformação genética, ferramentas importantes para processos biotecnológicos e estudos funcionais de genes específicos em tomateiro.

Gli stili APA, Harvard, Vancouver, ISO e altri

8

Aissa, Abdi Fatima. "Mitochondrial complex I dysfunction enhances in vitro plant organogenesis". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS136/document.

Testo completo

Abstract (sommario):

La régénération in vitro est un processus complexe largement utilisé pour la multiplication végétative ainsi qu'en recherche fondamentale pour étudier l'organogenèse. Malgré les diverses applications de la caulogenèse in vitro, les mécanismes de régulation impliqués restent mal caractérisés. Avant le début de mon doctorat, nous avons identifié un mutant d'Arabidopsis thaliana chez lequel un défaut du complexe I de la chaîne de transport d'électrons mitochondriale (CTEm) entraîne une augmentation du taux de régénération comparé au sauvage, mesurée sur des cals issus de protoplastes. Au début de mon projet doctoral, j'ai confirmé le lien entre le dysfonctionnement respiratoire et l'augmentation des taux de régénération en utilisant un inhibiteur spécifique du complexe I appelé roténone. Pour comprendre ce phénomène, j'ai étudié les mécanismes moléculaires et biochimiques liant la respiration mitochondriale et l'organogenèse in vitro. J'ai analysé différents mutants affectés dans l'activité du complexe I et conclu que le retard de croissance qui en découle est positivement corrélé avec le taux de régénération. Pour comprendre comment les perturbations de la CTEm affectent la formation des bourgeons, j'ai comparé les profils d'expression des gènes dans des tissus mutants du complexe I et dans des cals traités avec la roténone. Les résultats obtenus montrent, d’une part, que le profil d’expression des gènes est différent chez le sauvage et chez les mutants du complexe I et, d’autre part, que la roténone induit un stress oxydatif, inhibe la prolifération cellulaire et module les régulations hormonales. J'ai confirmé que la réponse oxydative induite par la roténone est rapidement relayée dans le cytosol en utilisant un bio-senseur de l’état redox cellulaire. Nos résultats suggèrent un lien de causalité entre un stress oxydatif induit par des perturbations respiratoires et la hausse du taux de régénération. Nos travaux pointent vers des méthodes alternatives pour améliorer l'efficacité de l'organogenèse in vitro par inhibition transitoire d'activités mitochondriales
In vitro shoot regeneration is a complex process routinely used for vegetative propagation and to study plant organogenesis. Despite multiple applications of in vitro shoot initiation, the regulatory mechanisms involved remain poorly understood. Prior to the beginning of my PhD thesis, we identified an Arabidopsis thaliana mutant in which a defect in the complex I of the mitochondrial electron transport chain (mETC) results in a higher shoot regeneration rate compared to wild type, measured on protoplast-derived calli. At the beginning of my PhD project, I confirmed the link between the respiratory defect and the shoot regeneration boost with a specific complex I inhibitor called rotenone. To understand this phenomenon, I investigated the molecular and biochemical mechanisms linking mitochondrial respiration and shoot organogenesis. For this purpose, I analyzed different mutants affected in the complex I activity and concluded that the resulting growth retardation is positively correlated with the regeneration rate. To understand how mETC perturbations promote shoot regeneration, I compared gene expression profiles in complex I mutant tissues and in calli treated with rotenone. Our data show, on the one hand, that gene expression profiles are different in complex I mutants and, on the other hand, that rotenone induces an oxidative stress, inhibits cell proliferation, and modulate hormonal regulations. I confirmed that the oxidative response induced by rotenone is rapidly relayed in the cytosol with a redox- sensitive biosensor. Altogether, our results suggest a causal link between an oxidative stress caused by respiratory impairments and shoot regeneration enhancement. Our findings point to alternative methods to promote in vitro organogenesis via transient inhibition of mitochondrial activities

Gli stili APA, Harvard, Vancouver, ISO e altri

9

Rocha, Gabriel Henrique Braga. "Análise do papel da via miR156/SQUAMOSA Promoter-Binding Protein-Like (SPL) na organogênese in vitro a partir de raízes de Arabidopsis thaliana". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11144/tde-17062016-180648/.

Testo completo

Abstract (sommario):

Os microRNAs (miRNAs) são pequenos RNAs endógenos não codantes de 21-24 nucleotídeos (nt) que regulam a expressão gênica de genes-alvos. Eles estão envolvidos em diversos aspectos de desenvolvimento da planta, tanto na parte aérea, quanto no sistema radicular. Entre os miRNAs, o miRNA156 (miR156) regula a família de fatores de transcrição SQUAMOSA Promoter-Binding Protein-Like (SPL) afetando diferentes processos do desenvolvimento vegetal. Estudos recentes mostram que a via gênica miR156/SPL apresenta efeito positivo tanto no aumento da formação de raízes laterais, quanto no aumento de regeneração de brotos in vitro a partir de folhas e hipocótilos em Arabidopsis thaliana. Devido ao fato de que a origem da formação de raiz lateral e a regeneração in vitro de brotos a partir de raiz principal compartilham semelhanças anatômicas e moleculares, avaliou-se no presente estudo se a via miR156/SPL, da mesma forma que a partir de explantes aéreos, também é capaz de influenciar na regeneração de brotos in vitro a partir de explantes radiculares. Para tanto foram comparados taxa de regeneração, padrão de distribuição de auxina e citocinina, análises histológicas e histoquímicas das estruturas regeneradas em plantas com via miR156/SPL alterada, incluindo planta mutante hyl1, na qual a produção desse miRNA é severamente reduzida. Além disso, foi avaliado o padrão de expressão do miR156 e específicos genes SPL durante a regeneração de brotos in vitro a partir da raiz principal de Arabidopsis thaliana. No presente trabalho observou-se que a alteração da via gênica miR156/SPL é capaz de modular a capacidade de regeneração de brotos in vitro a partir de raiz principal de Arabidopsis thaliana e a distribuição de auxina e citocinina presente nas células e tecidos envolvidos no processo de regeneração. Plantas superexpressando o miR156 apresentaram redução no número de brotos regenerados, além de ter o plastochron reduzido quando comparado com plantas controle. Adicionalmente, plantas contento o gene SPL9 resistente à clivagem pelo miR156 (rSPL9) apresentaram severa redução na quantidade de brotos, além de terem o plastochron alongado. Interessantemente, plantas mutantes hyl1-2 e plantas rSPL10 não apresentaram regeneração de brotos ao longo da raiz principal, mas sim intensa formação de raízes laterais e protuberâncias, respectivamente, tendo essa última apresentado indícios de diferenciação celular precoce. Tomados em conjunto os dados sugerem que o miR156 apresenta importante papel no controle do processo de regeneração de brotos in vitro. Entretanto, esse efeito é mais complexo em regeneração in vitro a partir de raízes do que a partir de cotilédones ou hipocótilos.
MicroRNAs (miRNAs) are endogenous small non-coding RNAs of 21-24 nucleotides (nt) in length that regulate target gene expression. They are involved in many aspects of plant development, both in the shoot and in the root systems. Among miRNAs, miRNA156 (miR156) regulates SQUAMOSA Promoter Binding-Like (SPL) transcription factor family affecting different plant development processes. Recent studies have shown that the miR156/SPL pathway has a positive effect both in the increase of lateral root formation and regeneration of shoots from leaves and hypocotyls in Arabidopsis thaliana. Because the origin of lateral root formation and in vitro shoot regeneration from primary root share similar anatomical and molecular features, in the present study was evaluated whether the miR156/SPL pathway, in the same manner that from aerial explants, is also able to influence the in vitro shoot regeneration from root explants. For this, it was compared regeneration rates, distribution pattern of auxin and cytokinin, histological and histochemical analyses of the structures regenerated in plants in with the miR156/SPL pathway is modified, including the mutant hyl1-1, in which the biosynthesis of this miRNA is severely reduced. Besides that, it was evaluated the expression pattern of miR156 and specific SPL target genes during in vitro shoot regeneration from primary roots of Arabidopsis it was observed that the alteration on the miR156/SPL pathway is capable to modulate in vitro shoot regeneration from the primary root of Arabidopsis and the distribution of auxin and cytokinin at the tissues and cells involved in the regeneration process. Plants overexpressing the miR156a have shown reduction in the number of regenerated shoots, and displayed a reduction in plastochron when compared with wild type plants. Additionally, plants expressing cleavage-resistant form of SPL9 (rSPL9) presented severe reduction in the amount of shoots, and extended plastochron. Interestingly, mutant hyl1-2 and plants rSPL10 did not show any shoot regeneration along the root, but high formation of lateral roots and protuberances, respectively, having rSPL10 presented evidence of precocious cell differentiation. Taken together, these data suggest that de miR156 and SPLs have an important role in the control the in vitro shoot regeneration process. However, its effect is somehow more complex in roots than in cotyledons or hypocotyls.

Gli stili APA, Harvard, Vancouver, ISO e altri

10

Raikar, Sanjeev Vencu. "Protoplast fusion of Lolium perenne and Lotus corniculatus for gene introgression". Phd thesis, Lincoln University. Bio-Protection and Ecology Division, 2007. http://theses.lincoln.ac.nz/public/adt-NZLIU20080214.105406/.

Testo completo

Abstract (sommario):

Protoplast fusion of Lolium perenne and Lotus corniculatus for gene introgression by Sanjeev V. Raikar Lolium perenne is one of the most important forage crops globally and in New Zealand. Lotus corniculatus is a dicotyledonous forage that contains valuable traits such as high levels of condensed tannins, increased digestibility, and high nitrogen fixing abilities. However, conventional breeding between these two forage crops is impossible due to their markedly different taxonomic origin. Protoplast fusion (somatic hybridisation) provides an opportunity for gene introgression between these two species. This thesis describes the somatic hybridisation, the regeneration and the molecular analysis of the putative somatic hybrid plants obtained between L. perenne and L. corniculatus. Callus and cell suspensions of different cultivars of L. perenne were established from immature embryos and plants were regenerated from the callus. Of the 10 cultivars screened, cultivars Bronsyn and Canon had the highest percentage of callus induction at 36% each on 5 mg/L 2,4-D. Removal of the palea and lemma which form the seed coat was found to increase callus induction ability of the embryos. Plant regeneration from the callus was achieved when the callus was plated on LS medium supplemented with plant growth regulators at different concentrations. Variable responses to shoot regeneration was observed between the different cultivars with the cv Kingston having the lowest frequency of shoot formation (12%). Different factors affecting the protoplast isolation of L. perenne were investigated. The highest protoplast yield of 10×106 g-1FW was obtained when cell suspensions were used as the tissue source, with enzyme combination A (Cellulase Onozuka RS 2%, Macerozyme R-10 1%, Driselase 0.5%, Pectolyase 0.2%), for 6 h incubation period in 0.6 M mannitol. Development of microcolonies was only achieved when protoplasts were plated on nitrocellulose membrane with a L. perenne feeder layer on PEL medium. All the shoots regenerated from the protoplast-derived calli were albino shoots. The highest protoplast yield (7×106 g-1FW) of L. corniculatus was achieved from cotyledons also with enzyme combination A (Cellulase Onozuka RS 2%, Macerozyme R-10 1%, Driselase 0.5%, Pectolyase 0.2%), for 6 h incubation period in 0.6 M mannitol. The highest plating efficiency for L. corniculatus of 1.57 % was achieved when protoplasts were plated on nitrocellulose membrane with a L. perenne feeder layer on PEL medium. The highest frequency of shoot regeneration (46%) was achieved when calli were plated on LS medium with NAA (0.1 mg/L) and BA (0.1 mg/L). Protoplast fusion between L. perenne and L. corniculatus was performed using the asymmetric somatic hybridisation technique using PEG as the fusogen. L. perenne protoplasts were treated with 0.1 mM IOA for 15 min and L. corniculatus protoplasts were treated with UV at 0.15 J/cm2 for 10 min. Various parameters affecting the fusion percentage were investigated. Successful fusions were obtained when the fusions were conducted on a plastic surface with 35% PEG (3350 MW) for 25 min duration, followed by 100 mM calcium chloride treatment for 25 min. A total of 14 putative fusion colonies were recovered. Shoots were regenerated from 8 fusion colonies. Unexpectedly, the regenerated putative hybrid plants resembled L. corniculatus plants. The flow cytometric profile of the putative somatic hybrids resembled that of L. corniculatus. Molecular analysis using SD-AFLP, SCARs and Lolium specific chloroplast microsatellite markers suggest that the putative somatic hybrids could be L. corniculatus escapes from the asymmetric protoplast fusion process. This thesis details a novel Whole Genome Amplification technique for plants using Strand Displacement Amplification technique.

Gli stili APA, Harvard, Vancouver, ISO e altri

11

Fernando, Kumudu. "Gene expression during regeneration of shoots in tobacco by tissue culture". Thesis, University of Bath, 1992. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305058.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

12

Safdar, M. Taifoor, Khawar Hanif e Shakeel Ahmad Ghumman. "Super-Regenerative Receiver (SRR) for short-range HF band applications". Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-2448.

Testo completo

Abstract (sommario):

This master thesis describes a radio reciever with simple architecture which operates at 20 MHz. This is based on low-cost amplifier design. Super-Regenerative Receiver (SRR)is re-examined for its simplicity, low-power and short-range wireless applications. Power consumption is kept to a minimal level without any change in the performance of reciever by providing minimum biasing to discrete devices. This report shows how with the help of modern computer based investigation and simulation tools, a much more wide-ranging characterization of the behavior of the reciever is possible.

The Simulation software used to implement this model i advanced Designed System, ADS2006A. This designed model consist of two stages,the linear pre-amplifier stage and the super-regenerative oscillator (non-linear stage). The linear stage has a 1th-order low band-pass filter which connects the input terminal end with the pre-amplifier, while the non-linear stage is consist of class with LC resonant tank, and the self-quenching circuit.

The fundamental quench frequency of this reciever is 8 kHz. In the simulation, the supplied voltage, VDD, is 5,0 volts is used which produced input current of 5,06 mA. The results show that the designed model presents its best performance at the 20 MHz radio frequency (RF).

Gli stili APA, Harvard, Vancouver, ISO e altri

13

Safdar, M. Taifoor, Khawar Hanif e Shakeel Ahmad Ghumman. "Super-Regenerative Receiver (SRR) for short-range HF band applications". Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-4209.

Testo completo

Abstract (sommario):

This master thesis describes a radio receiver with architecture which operates at 20 MHz.This is based on low-amplifier design. Super-Regenerative Receiver (SRR) is re-examined for its simplicity, low-power, and short-range wireless applications. Power consumption is kept toa minimal level any change in the performance of receiver by providing minimum biasing to discrete devices. This report shows how with the help of modern computer based investigation and simulation tools, a much more wide-ranging characterization of the behavior of the reciever is possible.

The simulation software used to implement this model is advanced Designed System, ADS2006A. This designed medel consists of two stages, the linear pre-amplifier stage and the super-regenerative oscillator (non-linear-stage). The linear stage has a 1st-order low band-pass filter which connects the input terminal end with the pre-amplifier, while the non-linear stage is consists of class C amplifier with LC resonant tank, and the self-quenching circuit.

The fundamental quench frequency of this reciever is 8 kHz. In the simulation, the supplied voltage, Vdd, is 5.0 volts is used which produced input current of 5.06 mA. The result show that the designed model presents its best performance at he 20 MHz radio frequency (RF).

Gli stili APA, Harvard, Vancouver, ISO e altri

14

Cohen, Susan Alese. "Regenerating Longleaf Pine on Hydric Soils - Short-Term Effects on Soil Properties and Seedling Establishment". NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-04282008-191226/.

Testo completo

Abstract (sommario):

Restoring longleaf pine ecosystems is essential for managing rare plant and animal species and protecting biological diversity in the southeastern Coastal Plain of the United States. Natural longleaf pine ecosystems range from xeric uplands to poorly-drained flatwoods and savannas. Most existing stands, however, occur on xeric to dry-mesic sites and approaches to restoring longleaf pine to wetter sites traditionally utilize intensive practices. There is little information available on the efficacy of these practices to establish longleaf pine seedlings on poorly-drained sites and their impacts on soil properties, seedling survival and growth, and the understory plant community. A research project was established at Marine Corps Base Camp Lejeune, NC to evaluate the effects of site preparation methods for returning longleaf pine on hydric soils with no natural seed source. Various site preparation treatments were evaluated in a field experiment, and results revealed greater growth and earlier emergence from the grass stage with more intensive site preparation. There was a marginal increase in soil nutrients, and a slight increase in foliar nutrients found with the more intensive treatments. Site preparation influenced seedling growth in the short-term and this was likely due to the cumulative effects of controlling competition and modifying the planting site. Marine Corps Base Camp Lejeune and other Department of Defense installations include both former and remnant longleaf pine ecosystems that support federally protected plants and animals such as the red-cockaded woodpecker - and thus face the challenge of restoring former, poorly-drained longleaf pine ecosystems. A land use history revealed that, largely due to its poorly-drained status and inaccessibility, the majority of disturbance on the research area occurred after the 1920âs and was largely due to forestry activities. Since purchasing the land area of the project in 1996, the Marine Corpsâ challenge has been to balance the mission of training and readiness with the need for restoration and long-term management of longleaf pine ecosystems. The results of this work provide natural resource managers with a scientific foundation for assessing choices to assist in this restoration and management effort.

Gli stili APA, Harvard, Vancouver, ISO e altri

15

Grishin, Mikhail. "Dynamics of continuously pumped regenerative laser amplifiers". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110628_134556-72562.

Testo completo

Abstract (sommario):

This thesis presents a detailed study of continuously pumped regenerative amplifiers based on long-relaxation-time laser media. The goal of the research was to develop a general pattern of complex dynamics peculiar to such systems at high repetition rates and to find a way to improve performance characteristics affected by instabilities. Basic parameters of the optimally coupled regenerative amplifier operating in stable regime were derived in analytical form. They include optimum initial and final gains, the maximum output pulse energy, the power dissipation, the multi-pass B-integral and the roundtrip number providing the maximum output energy. A comprehensive pattern of existing dynamic regimes (stable, quasi-periodic and chaotic) was represented in space of controlling parameters. It has been found that the space of unstable operation decreases as the seed pulse energy increases. A method of stability diagrams, which forms a systematic approach to the optimization of regenerative amplification dynamics and in particular allows one to determine the seed pulse level sufficient to maintain the operation stable, has been developed. Performance characteristics were determined in the critical range of repetition rates, where instabilities are pronounced at the most and analytical solutions are unavailable. The experiments, carried out using the diode pumped picosecond Nd:YVO4 laser system, exhibited a good agreement with theoretical inferences. It has been demonstrated that... [to full text]
Šioje disertacijoje tiriami nuolatinai kaupinami regeneraciniai stiprintuvai su ilgos relaksacijos trukmės lazerine terpe. Tikslas buvo išanalizuoti bendrus tokių sistemų sudėtingos dinamikos dėsningumus pasireiškiančios aukštų dažnių diapazone ir surasti būdą pasiekti maksimalias išėjimo impulsų energijas išlaikant jų stabilumą. Analitiškai aprašomos pagrindinės optimizuotų ir stabiliame režime veikiančių stiprintuvų charakteristikos, tokios kaip optimalūs pradinis ir galutinis stiprinimo koeficientai, maksimali išėjimo impulso energija, rezonatoriuje išsklaidytoji galia, daugelio praėjimų B-integralas ir rezonatoriaus apėjimų skaičius, su kuriuo gaunama maksimali išėjimo impulso energija. Nustatytos egzistuojančių dinaminių režimų (stabilaus, kvaziperiodinio ir chaotinio) sritys valdančiųjų parametrų erdvėje. Išsiaiškinta, kad nestabilaus veikimo sritis mažėja, kai užkrato impulso energija didėja. Sukurtas ir išplėtotas stabilumo diagramų metodas, kuris ne tik suformuoja sisteminį požiūrį į regeneracinio stiprinimo dinamikos optimizavimą, bet ir leidžia nustatyti užkrato energijos dydį, pakankamą stabiliam veikimui palaikyti. Nustatytos darbinės charakteristikos kritiniame impulsų pasikartojimo dažnių diapazone, kur neegzistuoja analitiniai sprendiniai ir nestabilumai yra labiausiai tikėtini. Teoriniai rezultatai patvirtinti eksperimentiškai diodais kaupinamoje pikosekundinėje Nd:YVO4 lazerinėje sistemoje. Pademonstruota, kad užkrato impulso energijos padidinimas susiaurina... [toliau žr. visą tekstą]

Gli stili APA, Harvard, Vancouver, ISO e altri

16

Gonçalves, Micael Ferreira Mota. "Development of novel short and long term studies in Enchytraeus crypticus". Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/18562.

Testo completo

Abstract (sommario):

Mestrado em Biologia Molecular e Celular
A maioria dos estudos ecotoxicológicos têm investigado os efeitos de curto prazo dos contaminantes. Comparativamente, tem sido desenvolvido pouco trabalho na avaliação dos efeitos a longo prazo dos químicos existindo portanto uma necessidade de preencher esta lacuna. De entre as espécies de solo usadas em ecotoxicologia estão os Enquitraídeos (Oligochaeta), membros importantes da mesofauna terrestre com diretrizes padrão para testar os efeitos ao nível da sobrevivência, reprodução e bioacumulação (ISO, 2004; OECD, 2010, 2004). Para a espécie Enchytraeus crypticus, existe também disponível o cDNA microarray com mais de 40 000 transcritos (Castro-Ferreira et al., 2014) sendo uma vantagem competitiva em relação a outras espécies padrão. O principal objetivo desta pesquisa foi desenvolver novos testes de curto e longo prazo, abrangendo novos/diferentes endpoints para E. crypticus. A habilidade de regeneração do E. crypticus foi descoberta e o processo de regeneração foi descrito; este pode ser adicionalmente utilizado para avaliar os efeitos de tóxicos em testes de curto prazo. O desenvolvimento embrionário de E. crypticus foi investigado e um teste de embriotoxicidade foi desenvolvido (pela primeira vez em um invertebrados do solo). O cádmio (Cd) foi usado como substância de teste para validar o teste embriotoxicidade dados os seus conhecidos efeitos embriotóxicos. Os resultados mostraram que o Cd causou uma diminuição no sucesso da eclosão devido a um atraso ou interrupção na formação de estruturas embrionárias. Um teste de longevidade (com avaliação da sobrevivência e reprodução ao longo do tempo) foi desenvolvido para E. crypticus. Este ensaio de exposição de longo prazo foi utilizado para avaliar os efeitos de nanopartículas de óxido de cobre (CuO-NPs) em comparação com CuCl2 revelando que CuO-NPs causou efeitos superiores (diminuindo a longevidade e reduzindo a reprodução) do que CuCl2, a uma concentração de efeito semelhante. Este ensaio traz um novo conceito em ecotoxicidade, a longevidade. Este é um especto particularmente importante quando o assunto é a toxicidade de nanomateriais (NMs), onde se espera que o tempo de exposição a longo prazo revele efeitos imprevisíveis através dos testes correntes de curto/longo prazo. O uso dos novos ensaios desenvolvidos podem melhorar a avaliação dos perigos dos produtos químicos.
Most of the ecotoxicity studies have investigated the short-term effects of chemicals. Comparatively, little work has been done in the assessment of the long-term effects of chemicals and there is a need to fill this gap. Among soil species used in ecotoxicology are Enchytraeids (Oligochaeta), important members of the terrestrial mesofauna with standard guidelines for testing effects at survival, reproduction and bioaccumulation level (ISO, 2004; OECD, 2010, 2004). For the species Enchytraeus crypticus, there is also available the cDNA microarray with more than 40 000 transcripts (Castro-Ferreira et al., 2014) being a competitive advantage in comparison to other standard species. The main goal of this research was to develop novel short and long-term tests, covering new/different endpoints, for E. crypticus. Regeneration ability of E. crypticus was discovered and the regeneration process was described; this can be further used as endpoint to assess the effects of toxicants in short-term studies. The embryonic development of E. crypticus was investigated and an embryotoxicity test was developed (for the first time in a soil invertebrate). Cadmium (Cd) was used as a test substance to validate the embryotoxicity test given its known embryotoxic effects. Results showed that Cd caused a decrease in the hatching success due to a delay or disruption in formation of embryonic structures. A lifespan test (with assessment of survival and reproduction over time) was developed for E. crypticus. This long-term exposure assay was used to assess the effects of copper oxide nanoparticles (CuO-NPs) in comparison with CuCl2 revealing that CuO-NPs caused higher effects (shortening lifespan and reducing reproduction) than CuCl2, at similar effect concentration. This lifespan assay brings a novel concept in ecotoxicity, the longevity. This is a particularly important aspect when the subject is nanomaterials (NMs) toxicity, where longer term exposure time is expected to reveal unpredicted effects via the current short/long-term tests. The use of the new assays developed can improve the hazard assessment of chemicals.

Gli stili APA, Harvard, Vancouver, ISO e altri

17

Raikar, S. V. "Protoplast fusion of Lolium perenne and Lotus corniculatus for gene introgression". Diss., Lincoln University, 2007. http://hdl.handle.net/10182/301.

Testo completo

Abstract (sommario):

Lolium perenne is one of the most important forage crops globally and in New Zealand. Lotus corniculatus is a dicotyledonous forage that contains valuable traits such as high levels of condensed tannins, increased digestibility, and high nitrogen fixing abilities. However, conventional breeding between these two forage crops is impossible due to their markedly different taxonomic origin. Protoplast fusion (somatic hybridisation) provides an opportunity for gene introgression between these two species. This thesis describes the somatic hybridisation, the regeneration and the molecular analysis of the putative somatic hybrid plants obtained between L. perenne and L. corniculatus. Callus and cell suspensions of different cultivars of L. perenne were established from immature embryos and plants were regenerated from the callus. Of the 10 cultivars screened, cultivars Bronsyn and Canon had the highest percentage of callus induction at 36% each on 5 mg/L 2,4-D. Removal of the palea and lemma which form the seed coat was found to increase callus induction ability of the embryos. Plant regeneration from the callus was achieved when the callus was plated on LS medium supplemented with plant growth regulators at different concentrations. Variable responses to shoot regeneration was observed between the different cultivars with the cv Kingston having the lowest frequency of shoot formation (12%). Different factors affecting the protoplast isolation of L. perenne were investigated. The highest protoplast yield of 10×10⁶ g⁻¹FW was obtained when cell suspensions were used as the tissue source, with enzyme combination 'A' (Cellulase Onozuka RS 2%, Macerozyme R-10 1%, Driselase 0.5%, Pectolyase 0.2%), for 6 h incubation period in 0.6 M mannitol. Development of microcolonies was only achieved when protoplasts were plated on nitrocellulose membrane with a L. perenne feeder layer on PEL medium. All the shoots regenerated from the protoplast-derived calli were albino shoots. The highest protoplast yield (7×10⁶ g⁻¹FW) of L. corniculatus was achieved from cotyledons also with enzyme combination 'A' (Cellulase Onozuka RS 2%, Macerozyme R-10 1%, Driselase 0.5%, Pectolyase 0.2%), for 6 h incubation period in 0.6 M mannitol. The highest plating efficiency for L. corniculatus of 1.57 % was achieved when protoplasts were plated on nitrocellulose membrane with a L. perenne feeder layer on PEL medium. The highest frequency of shoot regeneration (46%) was achieved when calli were plated on LS medium with NAA (0.1 mg/L) and BA (0.1 mg/L). Protoplast fusion between L. perenne and L. corniculatus was performed using the asymmetric somatic hybridisation technique using PEG as the fusogen. L. perenne protoplasts were treated with 0.1 mM IOA for 15 min and L. corniculatus protoplasts were treated with UV at 0.15 J/cm² for 10 min. Various parameters affecting the fusion percentage were investigated. Successful fusions were obtained when the fusions were conducted on a plastic surface with 35% PEG (3350 MW) for 25 min duration, followed by 100 mM calcium chloride treatment for 25 min. A total of 14 putative fusion colonies were recovered. Shoots were regenerated from 8 fusion colonies. Unexpectedly, the regenerated putative hybrid plants resembled L. corniculatus plants. The flow cytometric profile of the putative somatic hybrids resembled that of L. corniculatus. Molecular analysis using SD-AFLP, SCARs and Lolium specific chloroplast microsatellite markers suggest that the putative somatic hybrids could be L. corniculatus escapes from the asymmetric protoplast fusion process. This thesis details a novel Whole Genome Amplification technique for plants using Strand Displacement Amplification technique.

Gli stili APA, Harvard, Vancouver, ISO e altri

18

Georgitis, Kathryn M. "Evaluating Shade Bias in Insect Trap Catch and Assessing the Short- and Long-term Impacts of Herbicide Application in Regenerating Clearcuts on Flowering Plant Communities". Fogler Library, University of Maine, 2001. http://www.library.umaine.edu/theses/pdf/GeorgitisKM2001.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

19

Pan, Gong. "FenFlux : the short term climate response of carbon dioxide and methane fluxes from a regenerating and a semi-natural fen in East Anglia, United Kingdom". Thesis, University of Leicester, 2017. http://hdl.handle.net/2381/39874.

Testo completo

Abstract (sommario):

Peatlands store ~30% of global soil organic carbon (SOC) and are frequently carbon dioxide (CO2) sinks, while also being sources of methane (CH4) due to anaerobic decomposition under waterlogged soil conditions. Hence, the role of peatlands in the radiative forcing of the Earth’s atmospheric system and their impact on the global climate system is complex. This study presents the first long-term direct flux measurements of land-atmosphere CO2 and CH4 exchange at a temperate lowland fen peatland in East Anglia, UK. The dynamics and magnitude of CO2, H2O, CH4 and energy fluxes were quantified using the eddy covariance (EC) technique at two sites: a former-arable regenerating site (Baker’s Fen, BF) and a semi-natural fen (Sedge Fen, SF) at Wicken Fen NNR. This allowed investigation and comparison of ecosystem responses to climate variability and restoration. EC measurements at BF covered three annual cycles (2013 - 2015), and at SF two and a half cycles (August 2013 - December 2015). BF acted as a net CO2 source in all years, emitting 161.03±12.51, 83.61±11.53 and 98.39±13.31 g CO2-C m-2yr-1 in 2013, 2014 and 2015, respectively; it was a net CH4 source of 6.067±0.096 g CH4-C m-2yr-1 in 2013 and 2.009±0.087 g CH4-C m-2yr-1 in 2015, and of 2.845±0.103 g CH4-C m-2 (8th April - 31st December 2014). The annual carbon balance for BF was lower than average carbon losses from arable fens, indicating that restoration can achieve net carbon emissions reduction. SF was also a net CO2 source of 297.59±9.16 g CO2-C m-2 (1st August - 31st December 2013), and a large net CO2 sink of -356.86±49.13 g CO2-C m-2yr-1 in 2014 and of -243.78±15.25 g CO2-C m-2yr-1 in 2015. Large inter-annual variability in CO2 exchange at SF indicates sensitivity to climatic conditions, and highlights the need to maintain an appropriate water level height to prevent or reduce soil carbon losses to the atmosphere as CO2.

Gli stili APA, Harvard, Vancouver, ISO e altri

20

Sánchez-Duran, José Antonio. "Neural plasticity in premotor pathways of the Aplysia feeding system : short-term synaptic modulation of motor programs, synaptic interactions, regeneration of cerebral-buccal connections, and recovery of buccal motor programs /". free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3013019.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

21

Golinelli, Anna. "Development of an original 10 kHz Ti : Sa regenerative cavity allowing 17 fs CEP stable 1 kHz TW-class amplification or wavelength tunability". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS018.

Testo completo

Abstract (sommario):

Au cours de dix dernières années la science aux attoseconde ou Physique au champ-fort a été l’objet d’un fort développement. La production d’impulsions laser énergétiques de courte durée à haute cadence et stabilisées en CEP constitue la première étape pour accéder aux dynamiques ultra-rapides caractérisant l’interaction de la matière avec une source de lumière cohérente, intense et ultra-rapide. Le travail de cette thèse consiste à améliorer globalement les performances d’un système laser Ti:Sa à haute cadence optimisé pour la génération des impulsions attoseconde. Nous avons développé une nouvelle configuration de cavité régénérative fonctionnant à 10 kHz qui permet une meilleure gestion des effets thermiques dans le cristal. En sortie de l’amplificateur les impulsions atteignent des valeurs de puissance de 5 W en bande étroite (35 fs), ou 2.7 W en bande spectrale large permettant une compression des impulsions proche de 17 fs. La CEP des impulsions en sortie d’amplificateur a été stabilisée ; le bruit résiduel mesuré tir-à-tir est de 210 mrad pendant trois heures.L’amplificateur peut supporter également le fonctionnement en mode accordable, en sélectionnant des spectres de 30 à 40 nm de largeur à mi-hauteur et en accordant leur longueur d’onde centrale dans une gamme de 80 nm autour de 800 nm. Nous avons conçu et mis en fonctionnement un amplificateur multi-passages non-cryogéné à imagerie par lentille thermique pour accroître la puissance des impulsions jusqu’à 10 W à une cadence de 1 kHz. Le régime de forte saturation d’amplificateur garantit une variation négligeable (±3% pic à pic) de la puissance des impulsions en sortie du module, face à une variation importante de la puissance en entrée (±25% pic à pic) sur la bande spectrale accordable. L’amplification peut encore être plus importante grâce à une ligne d’amplification à refroidissement cryogénique, qui permet d’atteindre des puissances au niveau TW, à la cadence de 1 kHz, tout en maintenant un régime de courte durée (17.5 fs) et stabilité en CEP (350 mrad de bruit résiduel tir-à-tir). Nous proposons aussi une étude des sources de bruit de CEP dans les modules hautement dispersifs: nous avons conçu une nouvelle approche numérique sur la base d’un logiciel de tracé de rayon commercial (Zemax) pour évaluer les variations de CEP dans les modules contenant réseaux de diffraction
The last decade has seen a lot of progress in attosecond science or in strong field physics. Generating energetic, few-cycle laser pulses with stabilized Carrier-Envelope Phase at high repetition rate constitutes the first step to access the ultra-fast dynamics underlying the interaction of matter with intense, ultrashort coherent light source. The work of this thesis consists in globally improving the performances of a high repetition rate Ti:Sa laser system optimized for attosecond science. We present an original 10 kHz Ti:Sa CPA laser based on an newlydesigneddouble-crystal cavity for thermal lensing management. The amplifier delivers up to 5 W in narrow band mode (35 fs pulses), or 2.7 W in broad band mode, supporting 17 fs pulses after temporal compression. We demonstrate shot-to-shot CEP stabilization with a remaining noise of 210 mrad over three hours at the front-end output. In parallel to the short pulse duration operation mode, it is possible to use the front end in a wavelength tunability mode within a 80 nm range around 800 nm, with a resolution of 1 nm and 30 to 40 nm of bandwidth. We designed and demonstrated a complete water-cooled lens-less multipass amplifier using thermal lensing for modeadaptation boosting the pulse energy up to 10mJ at 1 kHz repetition rate (up to 10 W). The saturation regime of the amplifier ensures negligible variation (±3% peak to peak) of the output power for significant variation of the input power (±25% peak to peak) over the tunability range. The energy scalability of the front-end is demonstrated by coupling its output to cryogenically cooled amplifier, delivering 1 kHz, TW-class pulses at 17.5 fs and CEP stabilized with a residual noise of 350 mrad. A study of CEP noise sources in high dispersive module is also addressed, proposing a numerical approach based on a commercial ray-tracing software (Zemax) for predicting CEP fluctuation in grating based modules

Gli stili APA, Harvard, Vancouver, ISO e altri

22

Grishin, Mikhail. "Nuolatinai kaupinamų regeneracinių lazerinių stiprintuvų dinamika". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110628_134544-62447.

Testo completo

Abstract (sommario):

Šioje disertacijoje tiriami nuolatinai kaupinami regeneraciniai stiprintuvai su ilgos relaksacijos trukmės lazerine terpe. Tikslas buvo išanalizuoti bendrus tokių sistemų sudėtingos dinamikos dėsningumus pasireiškiančios aukštų dažnių diapazone ir surasti būdą pasiekti maksimalias išėjimo impulsų energijas išlaikant jų stabilumą. Analitiškai aprašomos pagrindinės optimizuotų ir stabiliame režime veikiančių stiprintuvų charakteristikos, tokios kaip optimalūs pradinis ir galutinis stiprinimo koeficientai, maksimali išėjimo impulso energija, rezonatoriuje išsklaidytoji galia, daugelio praėjimų B-integralas ir rezonatoriaus apėjimų skaičius, su kuriuo gaunama maksimali išėjimo impulso energija. Nustatytos egzistuojančių dinaminių režimų (stabilaus, kvaziperiodinio ir chaotinio) sritys valdančiųjų parametrų erdvėje. Išsiaiškinta, kad nestabilaus veikimo sritis mažėja, kai užkrato impulso energija didėja. Sukurtas ir išplėtotas stabilumo diagramų metodas, kuris ne tik suformuoja sisteminį požiūrį į regeneracinio stiprinimo dinamikos optimizavimą, bet ir leidžia nustatyti užkrato energijos dydį, pakankamą stabiliam veikimui palaikyti. Nustatytos darbinės charakteristikos kritiniame impulsų pasikartojimo dažnių diapazone, kur neegzistuoja analitiniai sprendiniai ir nestabilumai yra labiausiai tikėtini. Teoriniai rezultatai patvirtinti eksperimentiškai diodais kaupinamoje pikosekundinėje Nd:YVO4 lazerinėje sistemoje. Pademonstruota, kad užkrato impulso energijos padidinimas susiaurina... [toliau žr. visą tekstą]
This thesis presents a detailed study of continuously pumped regenerative amplifiers based on long-relaxation-time laser media. The goal of the research was to develop a general pattern of complex dynamics peculiar to such systems at high repetition rates and to find a way to improve performance characteristics affected by instabilities. Basic parameters of the optimally coupled regenerative amplifier operating in stable regime were derived in analytical form. They include optimum initial and final gains, the maximum output pulse energy, the power dissipation, the multi-pass B-integral and the roundtrip number providing the maximum output energy. A comprehensive pattern of existing dynamic regimes (stable, quasi-periodic and chaotic) was represented in space of controlling parameters. It has been found that the space of unstable operation decreases as the seed pulse energy increases. A method of stability diagrams, which forms a systematic approach to the optimization of regenerative amplification dynamics and in particular allows one to determine the seed pulse level sufficient to maintain the operation stable, has been developed. Performance characteristics were determined in the critical range of repetition rates, where instabilities are pronounced at the most and analytical solutions are unavailable. The experiments, carried out using the diode pumped picosecond Nd:YVO4 laser system, exhibited a good agreement with theoretical inferences. It has been demonstrated that... [to full text]

Gli stili APA, Harvard, Vancouver, ISO e altri

23

Oliveira, Leandro Silva de. "Propagação de Eucalyptus cloeziana F. Muell". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-05052014-154718/.

Testo completo

Abstract (sommario):

O Eucalyptus cloeziana se destaca pelas propriedades tecnológicas da sua madeira, principalmente em razão da sua durabilidade, densidade e resistência. Entretanto, essa espécie apresenta limitações quanto ao enraizamento adventício de estacas, dificultando a obtenção de mudas clonais e o avanço nos programa de melhoramento da espécie. Nesta perspectiva, o presente trabalho teve por objetivo avaliar a micropropagação de E. cloeziana a partir de materiais juvenis e adultos como uma técnica para a propagação da espécie. Para tanto, o trabalho foi dividido em quatro partes. No primeiro estudo, estabeleceu-se um protocolo de organogênese indireta de E. cloeziana a partir de hipocótilos e cotilédones. No segundo estudo avaliou-se o resgate de matrizes adultas de E. cloeziana através da indução de brotações epicórmicas em megaestacas. No terceiro estudo definiu-se um protocolo de micropropagação via proliferação de gemas axilares de matrizes adultas de E. cloeziana. Por último, no quarto estudo avaliou-se o rejuvenescimento in vitro de matrizes adultas de E. cloeziana por meio da micropropagação via proliferação de gemas axilares e a microestaquia, a partir das matrizes rejuvenescidas in vitro,para comprovar a viabilidade do cultivo in vitro como alternativa de propagação da espécie. A organogênese indireta de E. cloeziana mostrou-se possível e dependente do tipo de explante, dos reguladores de crescimento, suas concentrações e combinações utilizadas nas diferentes fases de morfogênese. As brotações adventícias foram micropropagadas e aclimatizadas com sucesso, obtendo-se mudas clonais de E. cloeziana. No resgate das matrizes adultas de E. cloeziana ocorreu maior indução de brotações epicórmicas para as megaestacas coletadas na época do ano com maior pluviosidade e temperatura. O diâmetro médio das megaestacas, compreendido entre 2,0 e 5,0 cm, correspondeu ao mais adequado para a obtenção de maior número de brotações epicórmicas no resgate das matrizes adultas de E. cloeziana. O protocolo de micropropagação das matrizes adultas de E. cloeziana foi estabelecido com sucesso, utilizando como explantes, brotações epicórmicas induzidas nas megaestacas. A multiplicação in vitro das microcepas foi realizada com êxito no meio de cultura WPM suplementado com BAP e ANA, cujas concentrações variaram entre os genótipos. Os tratamentos de \"pulse\" com GA3 não foi adequado para promover o alongamento in vitro das brotações, o qual foi obtido coma redução da concentração do BAP (0,1 mg L-1). A aclimatização e o enraizamento ex vitro das microestacas foi realizada com sucesso nos miniestufas, garantindo a obtenção de mudas clonais das matrizes adultas de E. cloeziana para a composição de um microjardim clonal. As microcepas das árvores matrizes de E. cloeziana apresentaram diferentes taxas de multiplicação in vitro, apresentando especificidades dos materiais genéticos à micropropagação. Os resultados da microestaquia das matrizes rejuvenescidas in vitro de E. cloeziana corroboraram as evidências de rejuvenescimento desses genótipos durante a micropropagação. Além disso, constatou-se que outros fatores, além da maturidade, podem estar atuando diretamente na recalcitrância do E. cloeziana ao enraizamento adventício. Dessa forma, comprovou-se a importância da micropropagação como uma ferramenta para a clonagem de E. cloeziana, abrindo perspectivas para investigações futuras para otimizar os métodos de propagação da espécie.
Eucalyptus cloeziana has importance for its wood technologic characteristics, mainly the durability, density and resistance. Moreover, this species has limitations on adventitious rooting of cuttings, having difficulties to obtain clonal seedlings and to advance in the improvement programs. In this perspective, the present work aimed to evaluate the E. cloeziana micropropagation by juvenile and mature explants as a technique for propagation this specie. Therefore, the work was divided into four basic studies. The first study was the establishment of the protocol to indirect organogenesis to E. cloeziana hypocotyls and cotyledons. In the second study evaluated the rescue of E. cloeziana adult matrices for epicormic shoots induction in crow branches. In the third study was definite a micropropagation protocol by axillary branching of E. cloeziana adult matrices. Finally, in the fourth study was evaluated the in vitro rejuvenation of E. cloeziana adult matrices to micropropagation by axillary branching and the micro-cutting technique of in vitro rejuvenated matrices to prove the in vitro culture viability to the propagation of this specie. The indirect organogenesis E. cloeziana was dependent of explant type and growth regulator and its concentration used in the different morphogenesis phases. The adventitious shoots were multiplicities and acclimatized with success to obtain E. cloeziana clonal seedlings. The vegetative rescue results of E. cloeziana adult matrices showed a higher induction epicormic shoots from branches collected in warmer and rain season. The medium diameter between 2.0 and 5.0 cm was considered the better to obtain higher epicormic shoots number in vegetative rescue. The micropropagation protocol of E. cloeziana adult matrices was realized with success using epicormic shoots, induced in the branches, like explants. The shoots in vitro multiplication was realized on WPM medium culture, supplemented with BA and NAA. The better growth regulators concentrations were different for each genotype. Treatments pulse with GA3 was not suitable to promote the elongation of shoots in vitro, which was obtained by the BA concentration reduction at 0.1 mg L-1. The in vitro shoots acclimatization and ex vitro rooting was performed in mini-incubators with success and it permit to obtain clonal seedlings from E. cloeziana adult matrices to form a clonal micro-garden. The shoots of E. cloeziana adult matrices showed different in vitro multiplication rates with specific-genotype responses to micropropagation. The micro-cutting technique results of E. cloeziana adult matrices provide evidence that occurred in vitro rejuvenation of these genotypes, during the micropropagation. Therefore, the nursery results showed that other factors, not only maturation, can be involved in the adventitious recalcitrance of E. cloeziana. In conclusion, the importance micropropagation like a biotechnological tool to propagation of E. cloeziana was proved and opened important perspectives for future investigations to optimize the propagation methods for this specie.

Gli stili APA, Harvard, Vancouver, ISO e altri

24

Sung, Lun-Chang, e 宋倫彰. "Adventitious shoot regeneration of eggplant interspecific hybrid". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/31162282829533295934.

Testo completo

Abstract (sommario):

碩士
國立屏東科技大學
農園生產系所
101
Eggplant (Solanum melongena L.) is a vegetable and medicinal plant good for human health; furthermore, eggplant is an important crop all over the world. A number of studies report the regeneration of large number eggplants through tissue culture; for example, researchers would add hormone in the tissue culture media to induce the plant regeneration. Many reports were also indicated that using different explants of eggplant such as the leaves, roots, cotyledons, hypocotyls, and nodes, to induce plant regeneration. However, the studies which induce regeneration of eggplant interspecific hybridization varieties with various light intensity condition were limited. Consequently, in our experiment will use leaf explants of eggplant treating with artificial hormones, such as Auxin (naphthaleneacetic acid, NAA), Cytokinin (6-benzyladenine, BA) and Thidiazuron (TDZ) and with different light intensity conditions to induce plant regeneration. In the study, the effect of leaf explants treated with NAA and BA to induce shoot regeneration eggplant interspecific hybridization varieties were not significantly. On the other hands, IV TDZ have higher efficiency shoot regeneration rates than NAA and BA. The in vitro shoot were obtained in MS medium supplemented with 0.1 mg/L TDZ, having an average shoot number of 4.94 ± 1.84 per leaf explants (not fix size) in normal light intensity (35μmol/m2/s) for 21 days; on the other hand, the leaf explants (5 mm2) cultured in MS medium supplemented with 0.1 mg/L or 0.25 mg/L TDZ which in vitro shoot number was more leaf explants than that none fixed size, having average 11.19 ± 2.54 and 12.30 ± 3.30 per explants, respectively. The best in vitro shoot induction was achieved on MS medium supplemented with 0.1 mg/L TDZ, with an average of 15.41±0.71 per leaf explants (0.5mm2) in low light intensity (13 mol/m2/s). In our experiment, histology analyzing indicated that the in vitro shoot was through the organogenesis adventitious shoot. Finally, the adventitious bud inducing from the leaf explants treated with 0.1 mg/L TDZ in low light intensity would be growing and development after subculture to MS medium with hormone free in the normal light intensity condition for 42days. Furthermore, the upper leaf explants have highest survival rates after subculture to the MS medium for 42 days. On the other hand, the adventitious shoot inducing from the leaf explants all of position wouldn’t be growing and development after subculture to the MS medium without any plant growth regulator for 42 days; moreover, that have lowest survival rate. We were fined the optimal light intensity and concentration of artificial hormones, TDZ, to induce leaf explants of eggplant regeneration. The future we can try to use TDZ to induce regeneration of other eggplant interspecific hybridization varieties in the future.

Gli stili APA, Harvard, Vancouver, ISO e altri

25

Su, Wei-Ting, e 蘇暐婷. "Somatic embryogenesis and shoot regeneration of Salix garcilistyla Miq". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/77869279153910774459.

Testo completo

Abstract (sommario):

碩士
國立宜蘭大學
園藝學系碩士班
98
Salix garcilistyla Miq. is perennial deciduous shrub of Saliaceae. It is important for flower of crop in area of Sunshin of Ilan, like warm, humid and abundant sunshine of climate. This study establish complete regeneration system of Salix garcilistyla Miq. by tissue culture to probe into conditions and method of plant regeneration used different explants such as shoot apex, nodal segments and leaves, also used paraffin section technique to observe process of growth regulator to induce callus differentiation, somatic embryogenesis and shoot regeneration. This study are length less than 0.5 cm of shoot apex of Salix garcilistyla Miq. ‘Lanyang No. 1’ , bud are not growth and easy to browning when culture in add different concentration of TDZ of solid medium. In light condition, the length about 0.5-1 cm of shoot apex culture in filter paper bridge in liquid medium, the medium no add TDZ have better growth and without browning, and bud browning rate raise follow with TDZ concentration increase, highest of browning rate of bud in add 0.5 μM TDZ medium. Leaf explants separately culture in add 27 μM 2,4-D of liquid or solid of MS medium, the callus form rate in liquid medium is rapid than solid medium, but amount of callus are not different. Leaf explants are easier to brownng in light condition（45±5 μmol m-2 s-1）than dark condition（0 μmol m-2 s-1）. That exhibit different luminosity Effects explant browning rate. Callus separately subculture in add different concentration of TDZ, BA, Kinetin and no add plant growth regulators of MS medium. The results are all of the highest amount of callus multiplication in no add plant growth regulators of MS medium. Callus at different concentrations of Cytokinins（TDZ、Kinetin、BA）medium will increase the amount of callus multiplication, but don’t induce shoot regeneration. Shoot regeneration in add 1μM NAA and 0.5μM kinetin of MS medium.

Gli stili APA, Harvard, Vancouver, ISO e altri

26

Shu, Ming-Chi, e 許銘志. "Adventitious shoot induction and plant regeneration of Begonia × hiemalis". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/46456165723731199206.

Testo completo

Abstract (sommario):

碩士
國立嘉義大學
農學研究所
95
Adventitious shoots were successfully regenerated using leaf or petiole of explants from Rieger Begonia ( Begonia × hiemalis ‘Barkos’ ). Leaf or petiole sections were cultured on MS medium containing different concentration of NAA ( 0.1、1 mg/l ) and BA ( 0.1、0.5、1、5 mg/l ). The culture medium was optimized for the leaf or petiole explants derived from shoot which was supplemented on MS medium with 1 mg/l NAA and 0.5 mg/l BA and observed 8.5 or 12.6 shoots from each explant after eight weeks, respectively. Hundred percent shoot regeneration and 8.4 shoots per explant was obtained when leaf cutting position near the petiole position of leaf explants and it was significantly different from leaf cutting position near the middle and margin of explants. Histological studies showed that adventitious shoots originated from both leaf or petiole epidermis layer and then differentiate to the formation of apical meristems and leaf primordial structures and it did not show intact somatic embryogenesis. Histological observation revealed that regeneration of leaf or petiole explants via organogenesis. Further elongation of adventitious shoots was obtained from each explant on full strength MS solid medium or liquid- shake medium with average of 10.9 and 12.2 plantlets, respectively. However, shoot only a few plantlets was obtained shoot of petiole explants on full strength MS solid medium or liquid-shake medium. All the regenerated plantlets were 90 % survival rate and continued to grow after the transfer to plastic pots. No morphological aberrations were observed in the regenerated plants.

Gli stili APA, Harvard, Vancouver, ISO e altri

27

Liang, Wenqing. "Factors affecting shoot regeneration and genetic transformation of a self-compatible accession of Lycopersicon peruvianum /". 1994. https://scholarworks.umass.edu/theses/3446.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

28

Chen, Yi-Rung, e 陳伊蓉. "Study on the Relationship Between Aldose Reductase and Shoot Regeneration in Rice Callus". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/00001220949412756538.

Testo completo

Abstract (sommario):

碩士
國立嘉義大學
農藝學系研究所
99
It’s well known that osmotic stress can induce somatic embryogenesis and further shoot regeneration in rice callus. The mechanisms of totipotency are less understood so far even though plentiful research has been discussed with respect to cell differentiation. The purpose of this study was explored the possible role of Aldose Reductase gene (OsARs), which is subjected to ABA and stresses regulation, during callus induction and shoot regeneration in rice. The immature embryos from three genotypes of rice relevant to OsAR5, Tainung 67 (TNG67; OsAR5 wild-type), OsAR5 overexpression transgenic lines (OxAR5), and OsAR5 T-DNA insertion mutant (KoAR5) were used in present study. The callus were derived from N6D2 (N6 basal medium containing 2 mgL-1 2,4-D) induction medium supplemented with different concentration of sorbitol (0, 0.3M, 0.6M), represented as N6D2S0, N6D2S3, and N6D2S6, respectively. It showed the callus induction rate, fresh weight, and water content were decreased significantly accompany with sorbitol concentration in all genotypes. In KoAR5 has the highest browning rate than the others. Besides, the 14-days-old of callus were transferred to N6K4N2 (N6 basal medium containing 4 mgL-1 kinetin and 2 mgL-1 NAA) regeneration medium. The result showed that has no plantlets regenerated from TNG67 in N6D2S0 and N6D2S3 treatment. It can be increased to 13% in N6D2S6 treatment. Besides, the shoot regeneration frequency in N6D2S3 and N6D2S6 from OxAR5 enhanced to 13% and 26% respectively. In opposite, all three treatments in KoAR5 have no shoot regenerated. It suggested that the expression of OsAR5 is relevant to shoot regeneration in rice callus. The reverse transcriptase polymerase chain reaction (RT-PCR) analysis and immunohistochemical localization of OsARs were further determined. The result showed that five OsARs genes can be detected in rice callus especially OsAR1 and OsAR2. The expression, except of OsAR5 is up-regulated by osmotic stress in TNG67 and OxAR5, the others seem have no significant difference no matter of with / without sorbitol treatment. In addition, it cannot detect any expression of OsAR5 in KoAR5 either callus induction or regeneration stage. According to the immunohistochemical analysis, the OsARs can be observed in the epidermis, peripheral layer, and tracheary elements during callus induction and shoot regeneration. The regenerable callus from N6D2S6 in TNG67 has more obviously distribution of OsARs. The result is consistent with our previous study that shoot regeneration frequency is increased significantly by osmotic stress treatment in rice callus. We suggested that OsAR5 is closely related to shoot regeneration induced by high concentration of sorbitol treatment. It may have roles on detoxification of reactive aldehyde compounds and osmotic adjustment under osmotic stress treatment. This is the first study to mention the correlation between plant differentiation and AR. More morphological, physiological, and gene expression analysis is necessary to clarify the possible role of OsARs during shoot regeneration in rice callus under osmotic stress treatment.

Gli stili APA, Harvard, Vancouver, ISO e altri

29

詹守怡. "Studies on protocorm like body induction 、multiplication and shoot regeneration of Phalaenopsis hybrids". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/86901209715151173095.

Testo completo

Abstract (sommario):

碩士
國立嘉義大學
農學研究所
91
The purpose of this research was to find the best media formula and cultural environment for PLB induction, PLB proliferation and shoot regeneration of Phalaenopsis hybrids. Using lateral buds removed from young flower stalks as explants, NDM（New Dogashima Medium）was the best medium formula for PLB induction in Phal. ‘Wedding promenade’ among the 1/2MS（Murashige and Skoog），VW（Vacin and Went） and Hyponex basal medium formula. The rate of PLB formation for lateral buds cultured on NDM medium containing NAA 0.1 mg/L and BA 1.0mg/L in Dtps. Nobby's Pink Lady ‘T699’ × Dtps. Taisuco Firebird ‘DL18’ and Dtps. Minho Princess was 34.6% and 26% respectively. However, The rate of PLB induction for lateral buds cultured on the NDM medium containing NAA 0.1 mg/L and BA 2.0mg/L in Phal. ‘Wedding promenade’ was 77﹪. Therefore, The effect of basal medium on PLB induction in Phalaenopsis showed lots of variations among the hybrids. Using short-stems removed from shoots in vitro, 1/2MS and Hyponex media were more available for PLB induction in Dtps. Minho Princess ‘MH903’ than NDM medium. Sucrose in the NDM medium was more productive for PLB induction than maltose and glucose in Dtps. I-Hsin Actor ‘KH5213’、Phal. Tinny White ‘TT1006’ and Phal. Taisuco Roseherz × Dtps. King Shiang’s Rose × Dtps. King Shiang’s Coral. The optimum carbonhydrate concentration in NDM medium for shoot and PLB formation ranged from 0.5%. PLBs as explants subcultured on 1/2MS, NDM and Hyponex medium formula in Phal. Taipei Gold ‘T. G.’ × Phal. Black Eagle ‘KH1872’ and Dtps. Sinica Ruby ‘KH5498’, not only PLB proliferation occurred, but also shoot regenerated. PLB subcultured on Hyponex medium containing NAA 0.1mg/L showed the highest rate of PLB proliferation in Phal. Taipei Gold ‘T. G.’ × Phal. Black Eagle ‘KH1872’. The highest number of regenerated shoots per explant appeared in the medium containing NAA 0.1mg/L and BA 2mg/L. However, PLB explants subcultured on Hyponex medium free of NAA and BA had the highest rate of PLB proliferation in Dtps. Sinica Ruby ‘KH5498’. It was found that Hyponex medium containing NAA 0.1mg/L and BA 4mg/L was best for shoot regeneration from PLB in Phal. Taipei Gold ‘T. G.’ × Phal. Black Eagle ‘KH1872’. Hyponex medium free of NAA and BA was more available not only PLB proliferation, but also for shoot regeneration in Phal. Taipei Gold ‘T. G.’ × Phal. Black Eagle ‘KH1872’ and Dtps. Sinica Ruby ‘KH5498’.

Gli stili APA, Harvard, Vancouver, ISO e altri

30

Huang, Wen-Lii, e 黃文理. "Studies on Carbohydrate Metabolism in Rice Callus During Shoot Regeneration Induced by Osmotic Stress". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/96394595848390674549.

Testo completo

Abstract (sommario):

博士
國立臺灣大學
農藝學系研究所
86
This thesis was conducted to explore the possible mechanisms of shoot rege neration from rice callus induced by osmotic stress. The relationships among osmotic stress, endogenous phytohormone levels, carbohydrate metabolisms,and s hoot regeneration were studied. In addition, the "regeneration-related factor s" were discussed in this thesis. The calli were induced from immature embr yos of two rice cultivars (Oryza sativa L.) and used for regeneration experime nts. One is Ai-Nan-Tsao 39, ANT39, whose callus showed high shoot regeneratio n ability. The other is Tainan 5, TN5, whose callus showed greatly increased regeneration frequency only after being exposed to an osmotic stress exerted b y either metabolizable (ex. sucrose) or non-metabolizable (ex. mannitol) sacch arides. At first, the callus growth, shoot regeneration frequency, water and osmotic potentials of culture mediumand callus under different osmotic stress treatment were determined. Then, the cellular contents of soluble sugars and starch, and the cellular localization and activities of enzymes related to the ir metabolism, including Sol-IT, Bound-IT, SS, AGPase, SPase, α-Amy, and β-A my of rice calli and shoot regenerating tissues were systematically analyzed. Finally, changes of carbohydrate metabolism was further investigated in TN5-An A treatment, in whichosmotic stress was replaced by 2mM anthranilic acid and 1 00μM ABA. The results showed, highly regenerable callus, ANT39-Dry, TN5-Su c18, and TN5-M6, have lower callus growth rate, water content, cellular water and osmotic potentials than un-regenerable callus, TN5. It suggested that sho ot regeneration is closely related to cellular osmotic status. In addition, h igher starch and sucrose contents at callus induction stage and a sudden incre ase or retaining higher glucose content at the first day after the callus bein g transferred to regeneration medium were found in highly regenerable callus. The starch and sucrose contents were decreased during shoot regeneration. Th e phenomenon of starch accumulation and disappear were also observed from hist ochemical analysis. On the other hand, there are no significant changes in ca rbohydrate contents and histochemical appearance in un-regenerable callus. We concluded, therefore, the higher starch content at callus induction stage and higher glucose content at the initiation of shoot regeneration stage were bot h the important "regeneration-related factors" in rice callus. The carbohyd rate metabolic pathway was different between ANT39-Dry and TN5-M6 although the changes of carbohydrate contents were similar. In ANT39, the lower Bound-IT and SS, higher Sol-IT activity at callus induction stage suggested that sucros e might be uptaken by sucrose transporter mainly. In addition, both AGPase an d α-Amy are higher at this stage suggested that the higher starch content is the result of higher stasch biosynthetic ability. At the initiation of shoot regeneration stage, higher expression and enzyme activity of α-Amy, higher So l-IT, and lower Bound-IT and SS activity were found. These results might expl ain that the higher glucose content might come from degradation of both starch and sucrose. In contrast, it showed greatly increase of Sol-IT, Cound-IT, an d SS at callus induction stage in TN5-M6. It suggested that sucrose uptake fr om sucrolytic pathway dominantly. At the same time, TN5-M6 showed similar AGP ase but lower α-Amy activity than TN5. Thestarch accumulation, therefore, mi ght be caused by lower degradation of starch in TN5-M6. At the initiation of shoot regeneration stage in TN5-M6, higher Bound-IT and Sol-IT, lower amylase activity were found. It might suggest that higher glucose content is due to h igher sucrose uptake by Bound-IT mainly. Because starch content was also decr eased at the same time, it might have another starch degradation pathway, for example, SPase, which showed higher SPase activity at this stage in TN5-M6. According to the observation of immunohistochemistry, it showed the distribut ions of SPase, β-Amy, and α-Amy are related to starch granules deposition. In addition, α-Amy is also localized at tracheary elements (TEs).SS1 was more dominantly localized at TEs and peripheral cells in callus. Besides, SS1 mig ht be related to starch biosynthesis. On the other hand, SS2 and SS3 were les s detected and only localized at some specialized tissues and parenchyma. A B ound-IT-like antibody was used in this thesis. It localized at peripheral cel ls especially at the side attached culture medium. In addition, it closely re lated to somatic embryogenesis and organogenesis during shoot regeneration. When TN5 callus was induced in MSD10 medium containing anthranilic acid andAB A, it showed slower callus growth, lower cellular water content and osmotic po tential, and higher starch and soluble sugars contents. After being transferr ed to regeneration medium, it also showed higher glucose content and decreased starch and sucrose contents. All the phenomenons were similar to those under osmotic stress treatment. Higher IAA and ABA levels inhibited all the sucrol ytic enzyme (Sol-IT, Bound-IT, and SS) and amylase activity. Therefore, the hi gher soluble sugars and starch contents might be resulted fromsucrose uptaking by sucrose transporter dominantly and inhibiting starch degradation, respecti vely. In conclusion, osmotic stress induced some changes of carbohydrate meta bolism, and was brought about shoot regeneration. Part of those changes were regulated by changes of endogenous IAA and ABA levels. But there are some pro cesses induced by osmotic stress might be regulated by other factors during sh oot regeneration.

Gli stili APA, Harvard, Vancouver, ISO e altri

31

Cordeiro, Daniela Correia. "Natural variation in the response to chemically induced shoot regeneration in Arabidopsis thaliana (L.) Heynh". Master's thesis, 2017. http://hdl.handle.net/10316/83326.

Testo completo

Abstract (sommario):

Dissertação de Mestrado em Biodiversidade e Biotecnologia Vegetal apresentada à Faculdade de Ciências e Tecnologia
Plants are able to regenerate new organs from differentiated tissues cultivated in vitro. Adventitious shoot organogenesis has applications in plant transformation and in vitro propagation. In Arabidopsis thaliana, this can be achieved using root explants trough a two-step protocol, where new shoot meristems are induced by the conversion of lateral root-like primordia. However, this capacity is highly variable among natural accessions. Thus, the goal of this work was to gain insight into the phenotypic and genetic variation across a range of wild type Arabidopsis accessions with respect to shoot regeneration from root explants and to identify genetic factors involved in chemically enhanced shoot regeneration.To this end, 190 Arabidopsis accessions were analysed for their shoot regeneration capacity using two protocols, that reflect the most suitable conditions for C24 and Col-0 accessions, and in the presence and absence of an enhancer of shoot regeneration, here called compound C1. High variability was observed in the identity and number of structures formed and in the response to C1 among the different accessions tested, that ranged from recalcitrant to highly responsive ones. C1 was shown to promote shoot induction since its effect was positive in almost all accessions. Also, the conditions of Col-0 protocol proved to be more efficient, resulting both in a higher shoot regeneration index and a higher induced shoot numbers per explant than those of C24 protocol for most of the accessions. However, Lp2-2, Kar-1, Kyoto, Cen-0, C24, Bla-1, Gel-1, Etna-2 and Sapporo-0 had a regeneration rate higher than 90% in the presence of C1, regardless of the protocol used.Genome-Wide Association analyses revealed the occurrence of genetic variations (SNPs) associated with the differences in shoot regeneration phenotype and the response to C1. From these genetic variations, a large list of candidate genes was deduced, reflecting the complexity and broad polygenic basis of shoot regeneration. Nevertheless, five genes are noteworthy: WUS, ACS10, ERF061, MIR167C and IPS1. The finding of WUS – a gene commonly known to be important in the regenerative capacity – proved the veracity of this approach, while the discovery of ethylene-related genes ACS10 and ERF1 provides an incentive for the hypothesis that ethylene is involved in shoot regeneration, which has already been reported as well. MIR167C and IPS1, that regulates the activity of other miRNA, are also noteworthy genes since other miRNAs have been shown required for in vitro shoot regeneration. Furthermore, genetic variations around WUS, ACS10 and IPS1 were found to be associated with shoot regeneration from root explants in Arabidopsis regardless of the specific conditions that plants were subjected to, meaning that they are likely causal genes. Thus, our results suggest that changes in WUS, miRNAs and ethylene signalling or homeostasis might be responsible for the variation observed in the regenerative capacity and that C1 might boost this capacity by modulating these factors/processes. Nevertheless, all candidate genes need validation to know whether they are indeed causal genes. That can be done by gene knock-outs, complementation tests and/or using the CRISPR/Cas9 tool, a method for targeted genetic engineering by which a good allele can be inserted into a poorly performing background and see whether it improves regeneration.
As plantas podem regenerar novos órgãos a partir de tecidos diferenciados cultivados in vitro. A indução de organogénese é um processo com muitas aplicações na transformação genética de plantas e na propagação in vitro. Em Arabidopsis thaliana, isso pode ser conseguido usando explantes radiculares através de um protocolo de dois passos, onde novos meristemas caulinares são induzidos a partir de primórdios das raízes laterais. No entanto, esta capacidade é altamente variável entre genótipos. Assim, o principal objetivo deste trabalho foi analisar de que forma explantes radiculares de genótipos selvagens de Arabidopsis respondem à indução de organogénese e identificar fatores genéticos envolvidos na regeneração de rebentos potenciada por um composto químico em estudo.A resposta organogénica foi testada em 190 genótipos de Arabidopsis usando dois protocolos que refletem as condições mais adequadas para os genótipos C24 e Col-0, na presença e ausência de um potenciador da regeneração de rebentos: composto C1. Os resultados mostraram uma alta variabilidade no tipo e no número de estruturas formadas e na resposta ao C1 entre os diferentes genótipos testados, que variaram de linhas recalcitrantes a linhas com uma elevada resposta. Nas condições testadas, o composto C1 mostrou ser promotor da indução de rebentos, pois o seu efeito foi positivo em quase todos os genótipos. Além disso, as condições do protocolo Col-0 provaram ser mais eficientes pois resultaram num maior índice de regeneração de rebentos e induziram um maior número de rebentos por explante do que as do protocolo C24 para a maioria dos genótipos. Contudo, Lp2-2, Kar-1, Kyoto, Cen-0, C24, Bla-1, Gel-1, Etna-2 e Sapporo-0 apresentaram uma taxa de regeneração maior que 90% na presença de C1, independentemente do protocolo usado.As análises de genome-wide association revelaram muitas variações genéticas (SNPs) associadas a diferenças na regeneração de rebentos e à resposta ao C1. A partir dessas variações genéticas, uma lista grande de genes candidatos foi deduzida, refletindo a complexidade e a ampla base poligénica envolvida na regeneração de rebentos. Ainda assim, há cinco genes que merecem destaque: WUS, ACS10, ERF061, MIR167C e IPS1. O envolvimento de WUS - um gene comummente conhecido por ser importante na capacidade regenerativa - provou a veracidade desta abordagem, enquanto a descoberta de genes relacionados com a ação do etileno, ACS10 e ERF061, sugere que esta hormona possa estar envolvida na regeneração de rebentos, à semelhança do que é referido em alguns artigos. MIR167C e IPS1, que regula a atividade de outro miRNA, são também de destacar uma vez que outros miRNAs têm-se mostrado necessários para a regeneração de rebentos in vitro. Além disso, variações genéticas em redor dos genes WUS, ACS10 e IPS1 apresentaram-se associadas com a regeneração de rebentos através de explantes radiculares em Arabidopsis independentemente das condições a que as plantas foram sujeitas, significando que estes são provavelmente genes causais. No seu conjunto, os resultados obtidos sugerem que mudanças em WUS, miRNAs e na sinalização ou homeostase do etileno podem ser responsáveis pela variação observada na capacidade regenerativa e que C1 poderá aumentar essa capacidade modulando estes fatores/processos. Estes dados necessitam de confirmação futura de maneira a verificar se os genes candidatos são realmente genes causais. Esta validação pode ser feita por eliminação de genes, testes de complementação e/ou usando a abordagem CRISPR/Cas9, um mecanismo de edição genética que permite, por exemplo, inserir um bom alelo num background de pouca performance e ver se ele afeta positivamente a organogénese.
Outro - - Centro de Ecologia Funcional - Department of Plant Production, Faculty of Bioscience Engineering, Ghent University - Bolsa de estágio pelo programa Erasmus+

Gli stili APA, Harvard, Vancouver, ISO e altri

32

Wang, Miki Mei-Chi, e 王美琪. "Study on antioxidant pretreatment of explants and medium composition on shoot regeneration of Paphiopedilum orchids". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/45760219789092611123.

Testo completo

Abstract (sommario):

博士
國立中興大學
園藝學系所
104
Abstract Explant browning was frequently found to impede plant regeneration and multiplication during in vitro propagation of Paphiopedilum (Paph.) orchids. To reduce explant browning, lateral flower buds (LFBs) of Maudiae Type Paph. Hsinying Web ‘Giant’ × Paph. Pulsar ‘Hsinying Flame’ were presoaked with 100 mg∙L-1 ascorbic acid (AA) solution or ascorbic acid +kinetin (AA+KT) solution before surface sterilization. AA+KT was superior to AA alone in controlling explant browning of LFBs. After AA+KT pretreatment, LFB explants excised from young floral buds grew better than those from mature flowers with lower explant browning rate and higher shoot induction rate. Supplement of cysteine (Cys) in culture medium effectively decreased polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) activities of Paph. explants during early incubation. Particularly, the presence of 50 -100 mg∙L-1 Cys depressed Paph. explant PAL activities compared with the control groups, and thus greatly reduced phenolic compounds, such as coumaric acid. The reduction of phenolic substrates for PPO oxidization significantly prevented enzymatic browning in Cys-containing media and subsequently induced shoot multiplication and rooting in Paph. explants. Medium with high nitrogen salts exacerbated the incidence of Paph. explant browning, therefore alteration of NO3--N/NH4+-N ratio and nitrogen form in media were investigated. Removal of ammonia nitrate in MS medium positively reduced explant browning and beneficially improved the development of Paph. mericlonal propagation. In addition, potassium nitrate as a sole inorganic nitrogen source lowered the occurrence of Paph. explant browning and increased shoot multiplication.

Gli stili APA, Harvard, Vancouver, ISO e altri

33

Bao, Yanghuan. "Genome scale transcriptome analysis and development of reporter systems for studying shoot organogenesis in poplar". Thesis, 2008. http://hdl.handle.net/1957/8329.

Testo completo

Abstract (sommario):

Vegetative propagation allows the amplification of selected genotypes for research, breeding, and commercial planting. However, efficient in vitro regeneration and genetic transformation remains a major obstacle to research and commercial application in many plant species. Our aims are to improve knowledge of gene regulatory circuits important to meristem organization, and to identify genes that might be useful for improving the efficiency of in vitro regeneration. In this thesis, we have approached these goals in two ways. First, we analyzed gene expression during poplar (Populus) regeneration using an AffymetrixGeneChip® array representing over 56,000 poplar transcripts. We have produced a catalog of regulated genes that can be used to inform studies of gene function and biotechnology. Second, we developed a GUS reporter system for monitoring meristem initiation using promoters of poplar homologs to the meristem-active regulatory genes WUSCHEL (WUS) and SHOOTMERISTEMLESS (STM). This provides plant materials whose developmental state can be assayed with improved speed and sensitivity. For the microarray study, we hybridized cDNAs derived from tissues of a female hybrid poplar clone (INRA 717-1 B4, Populus tremula x P. alba) at five sequential time points during organogenesis. Samples were taken from stems prior to callus induction, at 3 days and 5 days after callus induction, and at 3 and 8 days after the start of shoot induction. Approximately 15% of the monitored genes were significantly up-or down-regulated based on both Extraction and Analysis of Differentially Expressed Gene Expression (EDGE) and Linear Models for Microarray Data (LIMMA, FDR<0.01). Of these, over 3,000 genes had a 5-fold or greater change in expression. We found a very strong and rapid change in gene expression at the first time point after callus induction, prior to detectable morphological changes. Subsequent changes in gene expression at later regeneration stages were more than an order of magnitude smaller. A total of 588 transcription factors that were distributed in 45 gene families were differentially regulated. Genes that showed strong differential expression encoded proteins active in auxin and cytokinin signaling, cell division, and plastid development. When compared with data on in vitro callogenesis from root explants in Arabidopsis, 25% (1,260) of up-regulated and 22% (748) of down- regulated genes were in common with the genes that we found regulated in poplar during callus induction. When ~3kb of the 5' flanking regions of close homologs were used to drive expression of the GUSPlus gene, 50 to 60% of the transgenic events showed expression in apical and axillary meristems. However, expression was also common in other organs, including in leaf veins (40% and 46% of WUS and STM transgenic events, respectively) and hydathodes (56% of WUS transgenic events). Histochemical GUS staining of explants during callogenesis and shoot regeneration using in vitro stems as explants showed that expression was detectable prior to visible shoot development, starting 3 to 15 days after explants were placed onto callus inducing medium. Based on microarray gene expression data, a paralog of poplar WUS was detectably up-regulated during shoot initiation, but the other paralog was not. Surprisingly, both paralogs of poplar STM were down-regulated 3- to 6-fold during early callus initiation, a possible consequence of its stronger expression in the secondary meristem (cambium) than in shoot tissues. We identified 15 to 35 copies of cytokinin response regulator binding motifs (ARR1AT) and one copy of the auxin response element (AuxRE) in both promoters. Several of the WUS and STM transgenic events produced should be useful for monitoring the timing and location of meristem development during natural and in vitro shoot regeneration.
Graduation date: 2008

Gli stili APA, Harvard, Vancouver, ISO e altri

34

Smirnova, Tatiana. "Organogenesis in Vitro under Altered Auxin Signaling Conditions". Thesis, 2012. http://hdl.handle.net/1807/42900.

Testo completo

Abstract (sommario):

The ratio of auxin to cytokinin determines de novo organogenesis in plants. Relatively little is known about the effect of genetically altered auxin signaling on in vitro organogenesis. Here, callusogenesis, shoot, and root formation were studied in loss- (LOF) and gain-of-function (GOF) alleles in two phylogenetically related Auxin Response Factors (ARFs), MONOPTEROS (MP/ARF5) and NON-PHOTOTROPHIC HYPOCOTYL 4 (NPH4/ARF7). Reduced MP activity greatly diminished shoot regeneration, and partially diminished callusogenesis and root formation. LOF in NPH4 strongly decreased callusogenesis, and mildly decreased shoot and root regeneration in particular categories of explants. By contrast, organogenesis responses were strongly increased in aerial explants carrying the GOF transgene dMP. Thus, both MP and NPH4 seem to act as positive regulators of certain organogenesis processes and the GOF dMP transgene may be of interest for stimulating organogenesis in plant species with poor regeneration properties. Also, organogenesis in vitro may reveal unknown developmental ARF functions.

Gli stili APA, Harvard, Vancouver, ISO e altri

35

Lin, Jia Rong, e 林家榮. "Shoots regeneration via rhizome explants of C. sinense‘Shi-Ba Xyue-Shi’×C.formosanum". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/06861880172774369244.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

36

NontapotIssariyakul e 余大城. "Osteochondral Regeneration using PLGA Scaffolds under Short-term Continuous Passive Motion in a Rabbit Model". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/36827635340807420116.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

37

Chen, Po Yu, e 陳勃聿. "Induction of multiple shoots from the immature embryos of interspeciefic hybrids by Thidiazuron and plants regeneration in peanut". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/19979201804607649763.

Testo completo

Abstract (sommario):

碩士
國立中興大學
農藝學系
90
Summary The immature embryos of interspecific hybrids between cultivar TN11 and six wild type（A. cardenasii, A. rigonii, A. chacoense, A. corrotina, A. spegazzinii and A. monticola） were cultured on MS＋4 mg/l TDZ to induce multiple shoot and bud primordia. The collected bud and bud primordia was them used to investigate the effects of TDZ on shoots induction and proliferation, and to establish plant regeneration technique. The results were summarized as follows: 1. Buds of six interspecific hybrids cultured on MS medium containing different TDZ concentrations to induce multiple shoot. The induced percentage of shoot were significantly different among TDZ levels and crosses, but the averaged shoots were non-significant different. The mean numbers of bud primordia cultured on MS media supplemented with TDZ were significantly higher than on MS medium. Bud primordia cultured on MS media containing TDZ could induce shoots, but the efficiency was lower than buds as explants. 2. In all crosses, the induced percentage of shoot induced from shoot through three times subculture on MS＋2 mg/l TDZ medium could maintain above 50%, and the averaged shoot was stabilized. 3. TDZ induced the small and thickened multiple shoots, but MS medium without TDZ could increase the induced percentage of shoot and obtained normal shoots. Shoots subcultured with the MS medium without TDZ have the higher rooting percentage compare to MS medium containing TDZ, and root system was more healthy. 4. If the shoots of six interspecific hybrids transferred to MS media containing 50 mg/l ascorbic acid and three levels of NAA, the rooting percentage increased with NAA concentration. The MS medium containing 0.5 mg/l NAA produced the highest percentage of rooting and have more healthy root system. The percentage of rooting of all interspcific crosses were reduced with the subculture generation increased. 5. The recovery percentages of the rooted plantlets were ranged from 32.16% to 54.66% in six interspecific crosses. These plants were demonstrated as interspecific hybrids by chromosome number and morphological characteristics.

Gli stili APA, Harvard, Vancouver, ISO e altri

38

Li, Ren-Hong, e 李仁宏. "The Study on Short – term Employment Promotion Community Satisfaction in Rural Regeneration Communities － A Case Study of Tainan, Kaohsiung and Pingtung Country". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/81523465200486864464.

Testo completo

Abstract (sommario):

碩士
長榮大學
土地管理與開發學系碩士班
99
By the influence of financial tsunami, the economical industry of our country takes serious effect. The domestic unemployment rate rises higher gradually. Therefore Soil and Water Conservation Bureau decide to subsidize those legal community organizations or associations of countryside which aren’t located on urban planning area, to accelerate impetus of the countryside regeneration, to provide employment opportunity. The manpower of countryside will be full effective utilization and slow down the situation of high unemployment rate, namely “Accelerate the regeneration of short-term promotion of employment in rural areas” Interview Survey and document analysis as a research tool. Research data and relevant information are from interview of participations who are community director and workers. Assisted by ATLAS.ti qualitative analysis software, researchers found that the results supporting. This study found that “Accelerate the regeneration of short-term promotion of employment in rural areas” can provide reorganization of community, manpower as well as the related item, and it can increase the numbers of short-time job opportunity to reduce the impact which the unemployment brings, furthermore it may increase the countryside regeneration and the activation, employee's work degree of satisfaction belongs to satisfaction as well as the will of employment universal enhancement, community director and the employee measure degree of satisfaction belongs to satisfaction. Accelerate the regeneration of short-term promotion of employment in rural areas is labor intensive which is unable to strengthen the employment ability and to learn new skill. Accelerate the regeneration of short-term promotion of employment in rural areas.

Gli stili APA, Harvard, Vancouver, ISO e altri

39

Russo, Teresa Lopes. "Nova vida no palacete amarelo ao Chiado: estudo de caso de investimento imobiliário". Master's thesis, 2012. http://hdl.handle.net/10071/5463.

Testo completo

Abstract (sommario):

Em 1880, quando Eça de Queiroz escreveu “O Mandarim”, certamente, não imaginava que o seu “Palacete Amarelo ao Loreto” (o actual Palácio Valada e Azambuja), onde decorriam “algumas das mais afamadas festas” de Lisboa, se transformaria, mais de 130 anos depois, num empreendimento residencial, destinado ao arrendamento residencial de curta duração (short term rentals)1. O actual Palácio Valada e Azambuja foi alvo de uma intervenção de Reabilitação Urbana conduzida por um Fundo de Investimento Imobiliário, o Fundo Santa Casa 2004, gerido e administrado pela FundBox – Sociedade Gestora de Fundos de Investimento Imobiliário, SA. O trabalho que agora se apresenta pretende estudar esta intervenção de Reabilitação Urbana, procurando fazer um enquadramento teórico entre as seguintes temáticas: Mercado Imobiliário, Reabilitação Urbana e Fundos de Investimento Imobiliário. Importa demonstrar a pertinência dos Fundos de Investimento Imobiliário como veículos ativos e credíveis nos processos de Reabilitação Urbana e a importância da Reabilitação Urbana no Mercado Imobiliário. O desenvolvimento destas análises permite constatar que a utilização de incentivos fiscais na Reabilitação Urbana pode desempenhar um papel fundamental, sobretudo no contexto actual marcado pela existência de fortes restrições à realização de despesa pública, dificuldade acentuada dos negócios, nomeadamente, ao nível das vendas, da rendibilidade e do acesso ao crédito para financiamento da actividade. Seleccionou-se, para isso, um caso de estudo de aplicação prática de Reabilitação Urbana. Este exemplo contempla conforme mencionado anteriormente, a intervenção do Palácio Valada e Azambuja, desenvolvido no centro histórico da cidade de Lisboa. O projecto compreende dez apartamentos vocacionados para o segmento de turismo e lazer.
In 1880, when Eça de Queiroz wrote “O Mandarim”, certainly, he wouldn’t imagined that his Yellow Palace in Loreto (the actual “Valada e Azambuja” Palace) where took place some of Lisbon’s most famous parties, would became, more than 130 years later, a residential enterprise, focus on the short term rentals. The actual “Valada e Azambuja” Palace suffered an urban regeneration intervention made by a Real Estate Investment Fund, the “Santa Casa 2004” Fund, managed by FundBox – Sociedade Gestora de Fundos de Investimento Imobiliário, SA. This work intends to study this urban regeneration, through a guideline between the following themes: Real Estate Market, Urban Regeneration and Real Estate Investment Funds. It’s relevant to show the importance of Real Estate Investment Funds as an active and credible mean in the Urban Regeneration and the importance of Urban Regeneration in the Real Estate Market. The development of this analysis allows to see that the using of fiscal incentives in Urban Regeneration may be fundamental, mainly in the actual context, in which there are strong restrictions to the public spending, mostly in the selling level, profitability and the access to credit needed to finance the activity. Therefore, it was selected a practical case study of Urban Regeneration. This example includes the intervention on the “Valada e Azambuja” Palace, developed in Lisbon’s historical center. The project has ten apartments focus on tourism.

Gli stili APA, Harvard, Vancouver, ISO e altri

40

Thatcher, J., e Liz Sharp. "Measuring the Local Economic Impact of NHS Procurement in the UK: An Evaluation of the Cornwall Food Programme and LM3". 2008. http://hdl.handle.net/10454/1046.

Testo completo

Abstract (sommario):

Local procurement by public bodies is one type of Short Food Supply Chain (SFSC), which have been argued to contribute to economic regeneration and local sustainable development. In the current UK policy environment, quantifying actual local economic gains could add much-needed weight to arguments in favour of local procurement in the NHS and other public bodies. To aid such quantification, this paper exemplifies and evaluates the use of a ¿quick and simple¿ tool called LM3, designed to measure the local economic benefit of initiatives like SFSCs. LM3 is calculated for the Cornwall Food Programme (CPF), a localised procurement initiative. The findings confirm that the CPF has a considerable impact on the local economy. Notwithstanding this conclusion, difficulties in data collection combined with inaccuracies inherent to the LM3 process created a large margin of error in the findings. Moreover, a qualitative evaluation of the CPF added a valuable understanding of the wider economic impact of the CFP. The use of an even simpler and more reliable ¿LM2¿ multiplier tool is recommended for future studies, accompanied by some qualitative evaluation to create a fuller picture of local economic impacts.

Gli stili APA, Harvard, Vancouver, ISO e altri

Tesi sul tema "Shoot regeneration"

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili