Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Fertilisation.
Rozprawy doktorskie na temat „Fertilisation”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „Fertilisation”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
1
Huber, Johannes. "Fertilisation und embryonale Genomaktivierung". Diss., lmu, 2006. http://nbn-resolving.de/urn:nbn:de:bvb:19-55949.
Pełny tekst źródła
2
Yeates, Sarah E. "Fertilisation dynamics in Atlantic salmon". Thesis, University of East Anglia, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423579.
Pełny tekst źródła
3
Passos, Tiago Uchoa. "Biological Response to Ocean Macronutrient Fertilisation". Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18381.
Pełny tekst źródłaStreszczenie:
The aim of this study was to examine biological response to ocean macronutrient fertilisation on the oligotrophic waters offshore Sydney, Australia. This research investigates nutrient uptake, phytoplankton biomass growth, microzooplankton grazing and zooplankton and bacteria changes. After inoculating the sample with macronutrients there was a period of latency followed by rapid growth of phytoplankton until a maximum concentration was reached and subsequently decreased to a value similar to the initial concentration. Once the maximum concentration of phytoplankton decreased to a value similar to the initial concentration, another fertilisation (re-fertilisation) was conducted using the same seawater samples and the same concentration of macronutrients N & P. Results indicate that macronutrients N & P were initially limiting phytoplankton growth. The phytoplankton concentration maximum varied from 4 µg/l to 20 µg/l when add to an initial concentration of nutrients of 16 µmol N and 1 µmol P, while microzooplankton grazing varied from 30% to 77% of the total growth of phytoplankton biomass. It was observed that high phytoplankton concentration (20 µg/l) occurred where there was low grazing pressure (33 %) whereas low phytoplankton concentration (5.5 µg/l) occurred where there was high grazing pressure (71%). This suggests that phytoplankton concentration maximum was limited by microzooplankton grazing pressure rather than only macronutrient availability. The initial predominant zooplankton taxon group found in the samples are copepod cyclopod and calanoid. The species distribution was weakly affected by fertilisation and re-fertilisation. DNA sequencing results show that the initial predominant marine bacteria found in the samples are prochlorococcus and the total number of bacteria has doubled after fertilisation but remained similar after re-fertilisation. No remineralisation of particulate matter was observed after the macronutrients were exhausted.
4
Harrison, Daniel Patrick. "On the Potential of Ocean Fertilisation". Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15940.
Pełny tekst źródłaStreszczenie:
To date the global community has failed to effectively curtail growth in anthropogenic emissions of carbon dioxide, in the year 2016 we continue to track the IPCC 2005 ‘business as usual’ projection of annual emissions. The bleak outlook for stabilising the planets rising temperature by reducing reliance on fossil fuel energy has led to recent renewed calls for research into technological solutions. Only geoengineering to remove carbon dioxide from the atmosphere or a dramatic reduction in emissions can address the build-up of carbon dioxide in the atmosphere, and also act to alleviate the associated problem of increasing ocean acidification. Ocean fertilisation is one such technology which offers the prospect of partially addressing two pressing problems, that of rising atmospheric carbon dioxide levels and global food security. The potential of ocean fertilisation is examined here in terms of efficiency of carbon storage, potential benefits, implementation, environmental risk, cost, and societal values. Iron fertilisation was found to be less efficient (carbon stored / carbon fixed) and more expensive than macronutrient fertilisation, while both technologies have sequestration capacities of 1-1.5 Gt C yr-1 (10-15% of current emissions). Experimental studies on the response of plankton communities to macronutrient enrichment suggest that speculation of large ecological risk by encouraging harmful forms of phytoplankton appear to be overstated. The risks need to be compared to the costs of not acting to mitigate climate change, and to the environmental risk of increasing food production on the land to cope with a rising global population. It is found that ocean fertilisation has the potential to make a significant contribution to efforts aimed at mitigating climate change and also potential to contribute to improved food security, however the environmental and ecological implications of such a large scale intervention are poorly understood at this time.
5
Carroll, Michael. "Generation and propagation of sperm induced Ca²⺠waves in the ascidian oocyte". Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246669.
Pełny tekst źródła
6
Al-Chalabi, Sara. "Mass spectrometric characterisation of glycopolymers implicated in fertilisation". Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416135.
Pełny tekst źródła
7
Ng, Hung-yu Ernest, i 吳鴻裕. "Excessive ovarian response during in-vitro fertilisation treatment". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B29636218.
Pełny tekst źródła
8
Telaye, Asfaw. "Pollen physiology and fertilisation in Vicia faba L". Thesis, Durham University, 1990. http://etheses.dur.ac.uk/5960/.
Pełny tekst źródłaStreszczenie:
Abstract In many legume crop species, early-formed fruits or those located closest to the photosynthate are more likely to mature than other fruits. This is so in the Vicia faba crop. Based on physiological, nutritional and genetical aspects of seed development, several hypotheses are documented. However, Vicia faba pollen fertility has not been adequately studied. Thus, a series of experiments, consisting of studies of both in vitro and in vivo pollen viability, pollen tube growth and fertilisation ability were conducted using highly inbred lines (6-13 generations). Some of the in vivo experiments were conducted under Ethiopian field conditions. In some lines, even a low level of stress at 20 ºC for 4h at 100% relative humidity (RH) caused a dramatic drop in mean percent pollen germination. The overall results indicated that there was considerable variation (p≥0.001) among the Hues studied, in response to high temperature (20 to 35 C) and 100% RH. Vicia faba pollen showed high variability in fertility level. Overall significant differences exist in fertility (p≥0.01) among the genotypes studied. A fertility gradient exists along the stem: in most genotypes the fertility declining towards the upper nodes. In all of the genotypes, the first nodes carried more highly fertile pollen than the middle and the last flowering nodes. Also the middle nodes were more highly productive than the last nodes in all the genotypes. Thus, success of fertilisation depends to a degree on the source of pollen used. In an experiment concerning pollen storage, freshly dehiscent anthers desiccated at 25 C/6h and freeze dried for 45min, stored in either LN2 or at -80 ºC, gave more than 80% viability after 9 months of storage. Desiccation at RT for 24h and storage in either LN2 or at -80 C and at -20 C, still maintained pollen viability ≥80%. Mixed pollination studies conducted indicated that pollen from one or other of each pair of inbred fines, mixed on an equal weight basis, performed better as pollen parents on some maternal fines than on others. The importance of these findings with respect to synthetic variety and hybrid seed production in the text is discussed. The probable existence of genetic self-incompatibility is also discussed.
9
Ranford-Cartwright, Lisa C. "Cross-fertilisation in the malaria parasite Plasmodium falciparum". Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/14248.
Pełny tekst źródłaStreszczenie:
The objective of this work has been to investigate the frequency of cross-fertilisation between gametes of genetically distinct clones of the human malaria parasite Plasmodium falciparum. Previous genetic experiments involving both rodent malaria parasites in vivo and human malaria parasites in vitro have demonstrated higher than expected numbers of recombinants among the progeny of crosses. It has been suggested that this could be due to a favouring of cross-fertilisation over self-fertilisation in the mosquito phase of the life-cycle. The work has involved examining the genotypes of individual oocysts (derived from individual zygotes) resulting from mixed infection of two clones in mosquitoes. In preliminary work using the mouse malaria parasite P. yoelii nigeriensis attempts were made to examine the chromosomes of single oocysts using pulsed field gradient gel electrophoresis. However there was insufficient DNA in an oocyst to allow chromosomes to be visualised using this technique. The bulk of the work has been concerned with P. falciparum. In the first stage oligonucleotide primers suitable for use in the polymerase chain reaction (PCR) were designed to allow amplification of repetitive regions of two polymorphic antigen genes, denoted MSP1 and MSP2. The two clones of P. falciparum used in the crossing experiments possessed a different allele of each gene. These alleles were found to be recognisable as size differences of the PCR-amplified fragments on agarose gels. Gametocytes of the two clones were grown in vitro. Mixtures of gametocytes of each clone were made and fed to Anopheles stephensi or A. gambiae mosquitoes through membrane feeders. 9 to 10 days later the mosquitoes were dissected and their midguts were examined for the presence of oocysts. Individual oocysts were dissected from the midguts and the DNA extracted from them.
10
Rodgers-Gray, Barry. "The effects of soil amendments on the diseases and natural microflora of winter wheat". Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325166.
Pełny tekst źródła
11
Müller, Christina Heike. "Klinische Relevanz unterschiedlicher Spermatozoenparameter für die Fertilisation in vitro". [S.l.] : [s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=958028710.
Pełny tekst źródła
12
Wachter, Katja Ria. "In-vitro-Fertilisation vom Therapiemittel bei Fertilitätsstörungen zur Lebensplanungshilfe". Hamburg Kovač, 2006. http://www.verlagdrkovac.de/978-3-8300-2713-3.htm.
Pełny tekst źródła
13
Hofheinz, Marco. "Gezeugt, nicht gemacht In-vitro-Fertilisation in theologischer Perspektive". Wien Zürich Berlin Münster Lit, 2007. http://d-nb.info/987902113/04.
Pełny tekst źródła
14
Wachter, Katja Ria. "In-vitro-Fertilisation : vom Therapiemittel bei Fertilitätsstörungen zur Lebensplanungshilfe /". Hamburg : Kovač, 2007. http://www.verlagdrkovac.de/978-3-8300-2713-3.htm.
Pełny tekst źródła
15
Cahill, David John. "Preovulatory follicular function and fertilisation in women with endometriosis". Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295058.
Pełny tekst źródła
16
Dhillon, Rima Kaur. "Risk stratification for women undergoing in-vitro fertilisation treatment". Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6752/.
Pełny tekst źródłaStreszczenie:
The aim of this thesis was to explore three factors that are easily available and contribute important information for women before commencing in-vitro fertilisation (IVF) treatment: ethnicity, body-mass index (BMI) and thyroid disease. Results of the systematic review, cohort study and meta-analysis investigating ethnicity and IVF outcome showed South Asian and Black women have lower adjusted live-birth (LB) rates, after fresh cycle treatment, compared with White women. The relationship between BMI and IVF outcome was explored in a prediction model estimating chances of LB following first cycle. The model found BMI has reduced effect on IVF outcome when adjusting for other confounders such as age. The prevalence of thyroid dysfunction and thyroid peroxidase antibodies (TPOAb) was examined across the UK in >7000 women of reproductive age, and a cohort study investigating the effect of subclinical hypothyroidism (SCH) on IVF outcome was also performed. The prevalence of overt thyroid disease was 0.38% and subclinical disease 3.45%. Using an upper limit cut off for thyroid-stimulating hormone of 2.5mU/L the prevalence of SCH was 19.64%. The overall prevalence of TPOAb was 9.11%; this was 7.98% in euthyroid women. Finally, there were no significant differences in LB between euthyroid women and women with SCH.
17
Sunkara, Sesh. "Interventions for poor responders undergoing in vitro fertilisation treatment". Thesis, King's College London (University of London), 2013. https://kclpure.kcl.ac.uk/portal/en/theses/interventions-for-poor-responders-undergoing-in-vitro-fertilisation-treatment(63a0ad08-f73f-406e-93db-7aa226d4c160).html.
Pełny tekst źródłaStreszczenie:
This thesis examines the various interventions proposed for the management of poor responders undergoing IVF treatment. I began by performing a systematic review and meta-analysis to identify the ideal controlled ovarian hyperstimulation (COH) regimen for women with poor ovarian response undergoing IVF. The systematic review found the evidence to be inconsistent and inconclusive. The poor responders intervention trial (PRINT) was thus conceived. PRINT is an RCT comparing the gonadotrophin releasing hormone (GnRH) agonist long versus the GnRH agonist short versus the GnRH antagonist regimens for poor responders undergoing IVF. Results of PRINT showed the GnRH agonist long regimen to be efficacious. The relationship between egg numbers and live birth following IVF is poorly understood. I set out to investigate this by examining a large cohort of IVF cycles. I was able to demonstrate a strong association between egg numbers and live birth following IVF and justify the use of egg numbers as a primary outcome for PRINT. A frequent scenario faced in the management of women who have a poor response is whether to continue with their current IVF cycle or to cancel and start again on the assumption that there could be intercycle variability. I examined this hypothesis by comparing two consecutive IVF cycles with identical COH regimens. There was no significant intercycle variability in poor responders suggesting that the more cost effective option would be to continue with the IVF cycle Over the last decade a number of studies have been published on the use of androgen supplementation in poor responders. I conducted a systematic review and meta-analysis which demonstrated potential benefit from androgen supplementation but highlighted the shortcomings in the existing evidence. Finally, I conclude my thesis by examining the evidence behind some common clinical practices in the management of poor responders with suggestions for future research.
18
Dembele, Diomiho Monique. "Production de verdurettes biologiques : niveaux de fertilisation et biostimulants". Master's thesis, Université Laval, 2021. http://hdl.handle.net/20.500.11794/68778.
Pełny tekst źródłaStreszczenie:
Parmi les produits frais pouvant être cultivés en milieux urbains ou bâtiments, la production de jeunes légumes-feuilles riches en nutriments, communément appelés verdurettes, est en plein développement. La régie de fertilisation appliquée en culture biologique hors sol reste un déterminant majeur de la performance agronomique des cultures et de la qualité des produits. Par ailleurs plusieurs études rapportent que les biostimulants peuvent entraîner une production de biomasse plus élevée et améliorer la qualité de plusieurs légumes et fruits en augmentant l’absorption des éléments nutritifs ainsi que la résilience des plantes aux stress abiotiques et biotiques. Cependant, on sait peu de choses sur les apports optimaux en fertilisants et les avantages de l’ajout de biostimulants au milieu de culture de verdurettes biologiques. Par conséquent, ce projet visait à évaluer l’effet de (1) 5 concentrations de fertilisation biologique (0 % ; 50 % ; 100 % [14 g N m -2 ] ; 150 % ; 200 %) pour 3 milieux de culture (sans ou avec mycorrhizes et algues et acides humiques) (2) la réutilisation de ces milieux de culture et (3) 11 biostimulants (Bacillus pumilus, algues, Triacontanol, vermicompost, Trichoderma harzianum, acide humique, CaSiO3, engrais d’insectes, frass et farine de Hermetia illucens et témoin) sur la croissance, la productivité et l’activité biologique du sol de 6 espèces de verdurette. Les doses de fertilisation de 100 et 150 % ont été suffisantes pour la production de la chicorée, shiso, basilic et laitue, alors que l’épinard et la bette à carde ont bénéficié d’une fertilisation de 200 %. La teneur en NO3 observée dans les feuilles a été à l’intérieur des normes de la Commission Européenne UE n ° 1258/2011 (2 000 à 7000 mg NO3/kg selon l’espèce et saison. Peu de différences ont été observées entre le milieu de culture témoin et le milieu de culture amendé de mycorhizes. La réutilisation des milieux de culture a permis d’accroître les rendements. Par ailleurs, peu d’effets positifs des biostimulants sur le rendement et les paramètres photobiologiques ont été observés, suite au court cycle de production et l’absence de stress. Les traitements à base de frass ont toutefois augmenté l’activité biologique du milieu de culture. Avec les frass, la baisse du rendement observée pourrait impliquer une éventuelle immobilisation et/ou utilisation des éléments nutritifs dans le milieu de culture par les microorganismes du sol.Among the fresh produce that can be grown in urban settings or in buildings, the production of nutrient-rich baby leafy vegetables or microgreens is booming. The management of fertilization applied to organic cultivation remains a major determinant of the agronomic performance of greenhouse crops and of product quality. In addition, several studies reported that biostimulants can lead to higher biomass and improve the quality of several vegetables and fruits by increasing nutrient uptake and plant resilience to abiotic and biotic stresses. However, little is known about the optimal fertilization and the benefits of adding biostimulants to organic growing media. Therefore, this project aimed to evaluate the effect of (1) 5 concentrations of organic fertilization (0%; 50%; 100%; 150%; 200%) for 3 growing media (without or with mycorrizae, seaweed and humates), (2) reusing the growing media and (3) 11 biostimulants (Bacillus pumilus, seaweed extract, triacontanol vermicompost, Trichoderma harzianum, humic acid, CaSiO3, insect fertilizer, frass and meal of Hermetia illucens and control) on 6 species of microgreens. The growing media had significant effects on plant biomass. The growing medium amended with mycorrhizae, algae and humic acids increased the total fresh and dry biomass of shiso, basil and lettuce, while no gain in productivity was observed for spinach and Swiss chard. For chicory, only the total dry biomass was increased. Spinach and Swiss chard had the highest biomass with 200% fertilization, while chicory, shiso, basil and lettuce achieved optimal yield with 100 and 150%. In general, a positive correlation was observed between yield, nutrient uptake and mineral availability. However, the nutrient use efficiency decreased with increasing rates of fertilization. The fertilization treatments had a significant effect on leaf NO3 content, which increased with N concentration. However, leaf NO3 content was within the standards of the European Commission EUn°1258/2011; 2000-7000 mg NO3/kg spinach according to species and seasons. When reusing the growing media, similar effects of fertilizer x growing medium treatments were observed. However, biostimulants had few significant effects on yield and the photobiological parameters. This could be explained by the short growth cycle, added to the lack of stress in the plants. Frass resulted in an increase in the biological activity of the growing medium compared with the control without any biostimulant, but reduced yield which could imply a possible immobilization and/or use of nutrients by soil microorganisms, while humic acid decreased the FDA.
19
Brunengo-Basso, Stéphanie. "L'émergence de l'action de groupe, processus de fertilisation croisée". Aix-Marseille 3, 2009. http://www.theses.fr/2009AIX32067.
Pełny tekst źródłaStreszczenie:
L’action de groupe est une action en justice introduite par une personne physique ou une personne morale représentant d’un groupe de personnes sans avoir obtenu préalablement leur accord ou leur mandat exprès. Issue du droit anglo- saxon, elle existe sous la forme de la Class action aux Etats – Unis. Elle présente l’avantage de permettre la réparation de multiples préjudices individuels issus du comportement fautif d’un ou plusieurs mêmes auteurs. Ce modèle procédural est peu à peu introduit dans les systèmes juridiques de droit civil. Le Portugal, la Suède et l’Espagne se sont d’ores et déjà dotés de leur propre action de groupe. La Commission européenne conduit une réflexion pour introduire ce type de recours en droit antitrust au profit des consommateurs et des concurrents, victimes de pratiques anticoncurrentielles. L’objectif est d’améliorer l’efficacité du droit antitrust en garantissant la réparation du dommage né de la pratique illicite. Le développement des poursuites privées des pratiques anticoncurrentielles (private enforcement) doit permettre de renforcer le respect du droit antitrust par les opérateurs économiques. En France, de nombreux rapports et projets de loi ont vu le jour ces dernières années aux fins d’introduire la technique de l’action de groupe en droit positif. Toutefois, la réception envisagée par le droit français se limiterait aux litiges de droit de la consommation de faible montant. Cette perspective est décevante au regard du besoin de réparation des préjudices de masse qui s’expriment dans l’ensemble des branches du droit et notamment en droit antitrust, en droit de la consommation, mais aussi en droit boursier et en droit de l’environnement. L’ouverture de l’action de groupe à l’ensemble de ces contentieux favoriserait sans conteste l’accès à la justice des citoyens. Cependant, la démarche relative à son introduction en droit français doit reposer sur la prise en compte des éléments permettant d’assurer son efficacité. A cet égard, la question de la nécessaire adaptation du droit substantiel de la responsabilité civile se pose. L’action de groupe doit être facilitée dans sa mise en oeuvre sur le terrain de la preuve de la faute et du dommage subi. En outre, la dimension collective du préjudice soulève la question de la finalité punitive de la responsabilité civile, et partant de la consécration des dommages et intérêts punitifs. Enfin, l’action de groupe implique une mobilisation importante des ressources judiciaires et un contrôle juridictionnel poussé sur toutes les phases de la procédure. Son succès dépend donc largement de la capacité des acteurs judiciaires à accueillir et à conduire efficacement ce nouveau type de contentieuxA class action suit is a lawsuit that is filed by an individual or entity on behalf of a group of people, without having to first obtain their explicit consent or authorisation. The concept comes from the United States legal system. It offers the advantage of awarding damages for multiple individual losses resulting from the wrongful actions of a single party or group of parties. This procedural model has been gradually introduced into civil law systems in Europe. Portugal, Sweden and Spain have already established their own version of the class action suit. The European Commission is conducting a study with a view to introducing this type of action for antitrust suits filed on behalf of consumers and competitors who are victims of anticompetitive practices. The objective is to improve the efficacy of antitrust laws by ensuring compensation for losses incurred due to illegal practices. The rise in the number of private suits filed for anticompetitive practices, a concept referred to as "private enforcement," should encourage greater compliance with antitrust laws. In France, many reports and bills of law have been produced in the past few years that aim to establish the class action concept in French substantive law. However, the version under consideration for the French legal system would be limited to small claims consumer law. This stance is disappointing, considering the clear need in all areas of the law to award mass damages, such as in antitrust law and consumer law, as well as in securities law and environmental law. Extending the concept of the class action suit to these areas of litigation would unquestionably provide greater access to the courts for all citizens. However, when introducing the concept to the French legal system, certain aspects must be taken into consideration to ensure that it will be effective. For example, the necessary issue of adapting substantive law on civil liability must be addressed. The practical implementation of the class action suit must be facilitated, particularly with respect to proof of fault and proof of losses suffered. Moreover, the collective nature of the losses raises the issue of the punitive purpose of civil liability, and thus the consecration of punitive damages. In addition, a class action requires the mobilisation of significant legal resources and thorough court oversight in all phases of the proceedings. Its success will therefore depend largely on the ability of legal professionals to accept and pursue this new type of litigation effectively
20
Hofheinz, Marco. "Gezeugt, nicht gemacht : In-vitro-Fertilisation in theologischer Perspektive /". Zürich ; Berlin : LIT, 2008. http://swbplus.bsz-bw.de/bsz274010038inh.htm.
Pełny tekst źródła
21
Samson, Nicolas. "Fertilisation optimale de variétés de pommes de terre au Québec". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq33748.pdf.
Pełny tekst źródła
22
Sarraf, Christiana. "Optimisation de la fertilisation des fraisiers remontants cultivés hors sol". Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28467/28467.pdf.
Pełny tekst źródłaStreszczenie:
La culture de la fraise (Fragaria) est l’une des productions fruitières les plus répandues dans le monde. Ce petit fruit se cultive dans toutes les provinces du Canada et le Québec est considéré comme le leader canadien de cette production. Par contre, la culture fait face à des problèmes récurrents de maladies telluriques qui limitent les rendements. Pour pallier les problèmes phytosanitaires, on explore la possibilité de cultiver les fraisiers dans des systèmes hors-sol. Bien que la culture hors-sol des fraisiers se répande partout à travers le monde, les fruits issus de cette culture sont différents de ceux obtenus en culture au champ du point de vue de la qualité et du goût. L’objectif du présent projet est d’accroître la productivité et d’améliorer la qualité des fruits des fraisiers remontants cultivés hors-sol en optimisant la fertilisation. Nous avons comparé trois solutions nutritives afin de déterminer les rapports K/Ca et K/N favorisant l’obtention d’un meilleur goût des fraises et celle d’un rendement plus élevé. De plus, nous avons étudié l’effet de l’application foliaire de calcium sur le maintien de la texture et sur la durée de conservation des fruits. Les travaux ont porté sur deux sélections génétiques : Seascape de l’Université de la Californie et Charlotte du CIREF en France. De manière générale, la fertilisation potassique provoque une augmentation de la fermeté, sans toutefois influencer l’acidité et la teneur en sucres des fruits. De plus, le nitrate améliore les rendements. Les deux variétés ne répondent pas de la même façon à la fertilisation. De son côté, le Ca foliaire n’a pas eu d’effet sur la fermeté, ni la durée de conservation des fruits.
23
Caisse, Gabriel. "Importance de la fertilisation lors du boisement des tourbières résiduelles". Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24833/24833.pdf.
Pełny tekst źródła
24
Hyslop, Louise Ann. "Characterisation of the sperm calcium releasing factors that induces fertilisation". Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270828.
Pełny tekst źródła
25
Gearon, Ceinwen Mary. "Factors affecting fertilisation following the micro-injection of human spermatozoa". Thesis, King's College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338678.
Pełny tekst źródła
26
Fleming, Charlotte F. "Possible mechanisms of subfertility : epidemiological studies of in vitro fertilisation". Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390337.
Pełny tekst źródła
27
Fattore, Giovanni. "A cost benefit analysis of in-vitro-fertilisation in Italy". Thesis, London School of Economics and Political Science (University of London), 2008. http://etheses.lse.ac.uk/2746/.
Pełny tekst źródłaStreszczenie:
This thesis presents a full cost-benefit analysis of In-Vitro-Fertilisation (IVF) from a societal perspective. It is based on a contingent valuation survey administered through internet to a sample of the Italian population. A referendum format and a payment scale were used to elicit willingness-to-pay (WTP) for a publicly funded program providing IVF to infertile couples. WTP was also elicited for a hypothetical situation in which the respondent was asked to imagine being infertile and willing to have a baby. Overall, results show the feasibility of using this new method of administration of contingent valuation questionnaires. Responses reveal consistent patterns and the number of inconsistent answers is limited. WTP for private use (in case of infertility) and for a public program are positively associated with income, education, being within the fertility age range and being informed about infertility and IVF. The take-it-or-leave-it format and a variant of the payment scale method result in different mean WTP estimates, but simulated and actual referendum WTP are very similar. There is evidence of an anchoring effect since the values presented in the take-it-or-leave-it question had an impact on the answers to the modified payment card questions that followed. Mean WTP estimated from the different questions are consistently above the mean cost of providing IVF, as estimated on the basis of a full costing methodology. The IVF program shows net welfare benefits under several assumptions. The study shows that the societal benefits of an IVF program mainly derives from the high WTP of a minority of citizens who tend to be the most affluent, educated and familiar with infertility and IVF.
28
Morris, Paul James. "Carbon export from natural iron fertilisation in the Southern Ocean". Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/66262/.
Pełny tekst źródłaStreszczenie:
It has long been recognised that some oceanic regions have persistently low chlorophyll levels, even though inorganic nutrients are plentiful. Studies have shown that these high-nutrient, low-chlorophyll (HNLC) areas are depleted in iron, which is an essential micronutrient for phytoplankton growth. In HNLC regions biological production can be enhanced with artificial mesoscale iron fertilisation. However, the ability of artificially induced phytoplankton blooms to efficiently sequester carbon to mesopelagic depths is still an open question. SubAntarctic islands in the HNLC Southern Ocean are a natural source of iron and thus fuel the annual phytoplankton blooms observed in their proximity. One such bloom, tied to the Crozet Islands (52ºE, 46ºS), provided the opportunity to examine particulate organic carbon (POC) export during the austral summer of 2004/5. This work was imbedded into the multi-disciplinary CROZEX project thus providing a rich context for data interpretation. Based on satellite imagery, a high chlorophyll region (max = 4 µg l-1) north and downstream of the Crozet Islands was distinguished from a low chlorophyll region (typically 0.3 µg l-1) south and upstream of the islands. POC export estimates, obtained with the naturally occurring particle reactive radionuclide tracer, 234Th, were initially D15 mmol C m-2 d-1 in the high chlorophyll region, compared with D5 mmol C m-2 d-1 in the low chlorophyll region. After a moderately small increase in chlorophyll in the south (max = 0.7 µg l-1) the spatial variability in POC export was lost, resulting in equally high levels of POC export (ca. 20 mmol C m-2 d-1) throughout the study area. After comparing the daily rates of POC export with temporally integrated new production calculated from nitrate budgets, a different spatial pattern emerged. New production (NP) presented consistently higher values in the north, when compared to the south. Two hypotheses were formulated to explain this, 1) dissolved organic matter (DOM) and suspended particulate organic matter (sPOM) produced from NP was stored in the mixed layer with this effect relatively greater in the north, 2) the export event in the north was longer resulting in greater seasonal POC export. Investigation of the DOM pool revealed that DOM accounted for 46±7% of NP and was consistent across the whole study area. In contrast, sPOM accumulated at differential rates of 18±7% in the north and 0±7% in the south. This suggested that differential storage of sPOM was responsible for the lack of a latitudinal gradient in POC export after the relatively small increase in chlorophyll in the south. After investigating the second hypothesis, the daily rates of POC export were scaled to seasonal integrals using a silicon budget, which allowed the formulation of a seasonal carbon budget. This revealed that over the timescale of the study the magnitude of NP and POC export were not the same with this difference greatest within the northern high chlorophyll region. This was the result of relatively greater storage of sPOM in the north and had the effect of reducing the amount of easily exportable POC to mesopelagic depths. Thus both hypotheses contributed to better understanding carbon export in the Crozet region.
29
ANTONIADOU, THEODORA. "Evaluation statistique des regles de decision pour la fertilisation azotee". Toulouse 3, 1999. http://www.theses.fr/1999TOU30019.
Pełny tekst źródłaStreszczenie:
Le probleme croissant de la pollution de l'environnement par les engrais est a l'origine de l'interet d'optimiser leurs quantites apportees aux cultures agricoles. La determination des quantites d'engrais se fait par des regles de decision. Le terme regle de decision designe la procedure qui associe a tout individu de la population d'interet, les quantites d'engrais a recommander. L'objet de ce travail est le developpement d'une demarche statistique pour l'evaluation et la comparaison des regles de decision. Etant donne la grande diversite de decisions obtenues selon la regle consideree, nous proposons une methode de choix de regle de decision. Le critere du choix est l'esperance de la fonction objectif de la population d'interet. Pour l'estimation du critere trois estimateurs sont proposes : un estimateur parametrique, un estimateur de regression non parametrique et un estimateur non parametrique combine avec la technique de validation croisee. Une etude des simulations montre la superiorite de l'estimateur de regression non parametrique dont les proprietes theoriques sont etudiees dans le cadre de donnees longitudinales repetees. Enfin, l'extension de cette methode de choix a des regles concernant plusieurs decisions par individu (plusieurs apports d'engrais par individu) nous amene a etudier le comportement des estimateurs non parametriques multidimensionnels en fonction du nombre d'observations disponibles. Nous etudions ensuite les regles de decision fondees sur de l'information -relative a l'etat nutritionnel en azote des plantes- acquise en cours de culture. Nous considerons les regles qui determinent les quantites d'engrais avant et apres connaissance de l'information. En l'absence d'etude statistique sur le sujet, la premiere partie du travail est consacree a la proposition des regles de decision sequentielles qui prennent en compte cette information. La methode proposee se decompose en deux etapes : un travail de modelisation puis une optimisation de la fonction objectif. La regle de decision est definie comme solution du probleme d'optimisation basee sur la modelisation proposee. La decision sequentielle optimale est obtenue grace a l'algorithme de programmation dynamique. Enfin, en vue de verifier l'utilite de l'information, la comparaison des regles de decision obtenues avec et sans utilisation de l'information supplementaire s'effectue a l'aide d'un exemple dans lequel on considere des donnees reelles.
30
Dossou-Yovo, Wilfried. "Fertilisation phosphatée du maïs selon les conditions pédoclimatiques au Québec". Master's thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/29564.
Pełny tekst źródłaStreszczenie:
La fertilisation de démarrage du maïs à base de phosphate d’ammonium est une pratique courante au Québec. En effet, on présume que la croissance précoce du maïs conduit à une augmentation de rendement et à une amélioration de la qualité du grain. L’objectif de ce travail de recherche consistait à déterminer l’influence des facteurs climatiques, édaphiques et agronomiques sur le rendement, la qualité du grain de maïs et sur les doses de fertilisants phosphatés au démarrage. Une modélisation multiniveau des essais de fertilisation phosphatés du maïs recueillis au Québec de 1967 à 2009 a permis d’intégrer les facteurs déterminants pour la productivité de la culture du maïs. Les facteurs ayant un impact significatif sur le rendement sont les unités thermiques du maïs (UTM), le pH, les balances [Al
31
Papaligoura, Zaira. "The effects of in-vitro fertilisation on parent-infant communication". Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/22541.
Pełny tekst źródłaStreszczenie:
Precise analytical techniques using video are effective in the evaluation of emotional processes in mother infant communication, and these methods have been successfully applied to demonstrate important effects of maternal emotional disorders, such as post-natal depression. The present thesis proposes that this approach is useful in understanding parent-infant communication when IVF is employed. Communication between parents and IVF infants appears to develop along the "normal" path. When differences were observed, these occurred in both the IVF and INF groups, which indicates that IVF as such does not, in general, affect either parents or their infants, and any effect is due to the infertility experience common to both these groups. The finding that parental 'Caretaking' in both the IVF and INF groups continues in a considerable amount even at infant's age of 21 weeks, when the mothers in the NIP group have almost abandoned this behaviour, could indicate enhanced maternal empathy as a result of the infertility experience, in agreement with Golombok et al. (1996) who found that mothers who conceived through assisted reproduction show more emotional involvement than those with a naturally conceived child. However, this maternal behaviour may not be adaptive. Infants during the first two months of life have emotional sensitivity and can express an intimate personal response. Their engagement in this early period is often interrupted by expressions of need. In the next 2 months, however, together with a decline in the mother's salience as partner for communication and an increase in interest in the surroundings and in objects, there is also a decline in expressions of need. These changes, which originate within the infant, lead the mother to adapt unconsciously. Increased caretaking by mothers in the IVF and INF groups could be viewed as an indication of maternal overprotection, possibly due to prolonged anticipation of pregnancy as a result of infertility.
32
Christmann, Leandro. "Acquisition of meiotic competence in growing porcine oocytes". Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339451.
Pełny tekst źródła
33
Jury, Jennifer Anne. "Studies on fertilin and related MDC genes". Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484281.
Pełny tekst źródła
34
Bahrami, Mohammed. "A novel amino acid combination supports the in vitro maturation and fertilisation of bovine oocytes". Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/25067.2.
Pełny tekst źródłaStreszczenie:
In vitro maturation (IVM) of oocytes assists cattle producers to maximise the number of offspring from genetically superior animals. This technology has significant commercial benefits to the cattle industry. Through collection and maturation of multiple oocytes, producers increase the number of embryos produced from those animals with the desired production traits. Suboptimal culture conditions limit the proportion of metaphase II (MII) oocytes following IVM, affecting the viability of IVM as an assisted reproductive technology (ART). Improving IVM culture conditions will increase the proportion of MII oocytes that can be fertilised for the purpose of embryo production.
Maturation medium is supplemented with hormones including 17 β-estradiol, follicle stimulating hormone (FSH) and luteinising hormone (LH). FSH and LH activate the mitogen-Activated Protein Kinase 3/1 (MAPK3/1) and protein kinase c (PKC) signalling pathways, which are involved in the resumption of meiosis and germinal vesicle breakdown (GVBD). Maturation medium is also supplemented with amino acids, which are energy sources and can act as pH and osmoregulation during IVM. Additionally, a protein source, either fetal bovine serum (FBS) or bovine serum albumin (BSA) is added to maturation medium. Whilst the use of these supplements in IVM has been extensively studied, their optimal combination remains controversial.
The addition of FSH to the commercial medium, Tissue Culture Medium 199 (TCM199), achieved nuclear maturation, but there was no increase in the proportion of MII oocytes with the addition of 17β-estradiol or human chorionic gonadotropin (hCG). To determine the effects of amino acids, bovine cumulus oocyte complexes (COC) were matured in a simple inorganic salt solution (M1) supplemented with multiple amino acids combinations. The data shows that the addition of Glutamine, proline, and isoleucine to M1, results in %MII oocytes, comparable to TCM199. However, when cystine was added to glutamine, proline, and isoleucine, the %MII was significantly reduced. It was hypothesised that cystine activates the SLC7A11 (xCT) antiporter, which exports intracellular glutamate resulting in reduced glutathione (GSH), leading to increased reactive oxygen species (ROS). Live-cell imaging and mass-spectrometry data show ROS production is higher in oocytes cultured with cystine, and that their glutamate content was significantly lower than control oocytes. However, there was no difference in the GSH content of oocytes matured in the presence of cystine. Furthermore, the xCT antiporter was only present in the nuclear envelope at the germinal vesical stage of development.
It was hypothesised that cystine affected the maturation promoting effects of glutamine, proline, and isoleucine competitive uptake through membrane transporters. Using radiolabelled glutamine and proline, it was observed that cystine blocked proline uptake at the 24 h timepoint of IVM. This suggests that the maturation promoting effects of proline are inhibited by cystine. Similarly, isoleucine inhibited proline uptake, but it is likely that isoleucine compensates for proline activity.
Data presented here show that supplementation of a simplified inorganic salt solution with glutamine, proline, isoleucine and FSH supports reliable and reproducible nuclear maturation of bovine oocytes. It also demonstrates that under certain conditions, amino acids such as systine, cause a reduction in the proportion of MII oocytes following IVM. The data acts as a foundation to further investigate the role of amino acids in oocyte maturation with the aim of improving culture conditions and the overall viability of IVM as an assisted reproductive technology.
35
Holthaus, Eva. "Darstellung der In-Vitro-Fertilisation und verwandter Verfahren in deutschen Printmedien". [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=969860013.
Pełny tekst źródła
36
Painchaud, Jacques. "L'azote du sol et la fertilisation de la pomme de terre". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0016/MQ37155.pdf.
Pełny tekst źródła
37
Jansson, Johanna. "The influence of plant fertilisation regime on plant-aphid-parasitoid interactions /". Uppsala : Dept. of Entomology, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/a415.pdf.
Pełny tekst źródła
38
Campbell, Karen. "The relationship between calcium and metabolism in mouse eggs at fertilisation". Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/54106/.
Pełny tekst źródłaStreszczenie:
At fertilisation in mammals a series of Ca2+ oscillations are initiated that activate development. These Ca2+ oscillations cause the reduction of mitochondrial NAD+ and flavoproteins, suggesting that they might also stimulate changes in cytosolic ATP levels. Many events at fertilisation are triggered that require ATP; however, the changes in ATP during fertilisation are poorly defined. In this thesis intracellular C a2+ and ATP levels in individual m ouse eggs were m easured by monitoring the fluorescence of a C a 2+ dye (Oregon green bapta dextran) and lum inescence of firefly luciferase. During fertilisation of m ouse eggs it w as found that there are two phases of increase in ATP in both the cytosol and the mitochondria, during the series of sperm-induced Ca2+ oscillations. The increase in ATP is Ca2+ dependent since it did not occur when Ca2+ oscillations were prevented by BAPTA injection and, were abrogated by extracellular Ca2+ chelation. Additionally, it w as not seen when eggs were activated by cycloheximide, which does not cause a Ca2+ increase. The ATP increase is likely to be caused by oxidative phosphorylation by the mitochondria since the ATP levels in substrate free media are recovered by the addition of pyruvate. This recovery is blocked by the pyruvate uptake inhibitor ar-Cyano-4-hydroxycinnamic acid. T hese data suggest that mammalian fertilisation is associated with a sudden but transient increase in cytosolic ATP via oxidative phosphorylation, and that Ca2+ oscillations are both necessary and sufficient to cause this increase in ATP. Work in this thesis has also investigated the functionality of the sperm factor PLC?. Using luciferase tagged PLC constructs, the Ca2+ oscillation inducing ability of a series of PLC? truncated constructs, PLC5 and PLCy have been established. Results show that PLC? activation of m ouse eggs cannot be reproduced by other PLCs and that the C2, EF1 and catalytic site on the X domain are all essential for causing C a2+ oscillations.
39
Bertram, Caroline. "Fertilisation promoting peptide : a role in the diagnosis of prostate disease?" Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389648.
Pełny tekst źródła
40
Bennison, Clair. "Sperm morphology and fertilisation success in the zebra finch Taeniopygia guttata". Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/5107/.
Pełny tekst źródłaStreszczenie:
The aim of this study was to understand how variation in sperm morphology influences sperm swimming velocity, and consequently, the fertilisation success of males in a competitive context. Chapter 2 provides the methods behind the three key aspects underpinning the work described in this thesis. The set-up and maintenance of the selective breeding regime producing the population of zebra finches is described. The procedures involved in the collection of sperm, and assessment of sperm quality are then given in detail. Chapter 3 describes the artificial selective breeding regime, involving the three lines (long, intermediate and short) used to investigate how sperm morphology responds to selection on sperm total length. The tail and total length of sperm respond similarly to artificial selection, with decreasing and increasing lengths observed in the short and long selection lines, respectively. There were differences in the relationships between various sperm components in the three lines, for example midpiece and tail length were positively associated in the short selection line, yet generally, there was a negative relationship between these traits observed across the long and intermediate selection lines. Chapter 4 focuses on the genetic relationships that underpin the phenotypic associations evident in Chapter 3, and how these genetic relationships may determine the evolutionary trajectory of sperm morphology in response to selection. The difference in phenotypic relationships in the short selection line compared to the long and intermediate lines originate from a difference in genetic covariance between the sperm components across the lines. Chapter 5 uncovers the possibility that phenotypic changes in sperm morphology may be constrained by stabilising selection, based on the evidence that increased sperm swimming velocity is associated with absolutely larger component dimensions, but only up to certain values, beyond which swimming velocity declines. Chapter 6 draws together the work carried out through this thesis, and tests the hypothesis that longer, faster swimming sperm have a fertilisation advantage compared to shorter and slower swimming sperm in a competitive situation. There was a strong effect of sperm length on the competitive ability of sperm, but this advantage was mediated by complex interactions between the male and female selection history, and the different relationships that these male - female mating combinations have on the proportions of sperm that finally reach the ovum.
41
Kidd, Jonathan David. "Disentangling the effects of long-term fertilisation on soil carbon dynamics". Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3648.
Pełny tekst źródłaStreszczenie:
The application of fertilisers has greatly increased agricultural yields. However, it has also had wide ranging consequences for ecosystem properties and processes, generating concern over the long-term sustainability of fertiliser management. Despite this, there is considerable uncertainty regarding the long-term impacts of fertilisation, especially on soil carbon, and this is largely due to the paucity of published findings from long-term experiments. In this project very long-term field experiments and a short-term microcosm trial were used to investigate the effects of fertilisation on agroecosystem properties with a particular focus on soil carbon dynamics. The effects of long-term fertiliser addition on key ecosystem properties in the Palace Leas Hay Meadow Experiment was determined and compared with those observed at other long-term and with short-term experiments. Farmyard manure addition was found to have many benefits over the use of inorganic fertilisers for improving agricultural production including higher nutrient availability, hay yields and the prevention of soil acidification. The magnitude of short- and long-term effects of fertilisation differed markedly, underlining the value of using long-term experiments to realise the true ecosystem response. The relative importance of three major classes of fertiliser-mediated mechanism was also evaluated using structural equation modelling and a complementary ley-arable rotation experiment. These studies found that soil C dynamics were altered by both direct (nutrient) and indirect (plant community- and soil pH-change) effects of fertilisation. Soil pH was the primary regulator of the microbial response to fertilisation, with soil acidification effects strongly negatively affecting microbial functioning when it reduced soil pH below 5. A microcosm study indicated that these effects of acidification on the microbial community cannot easily be reversed. As microorganisms regulate biogeochemical cycles which are critical for food production, fertiliser-induced acidification could therefore hinder long-term agricultural sustainability. Accordingly, soil pH in fertilised systems must be managed vigilantly.
42
Massey, Paul Andrew. "Interactions between phosphorus fertilisation and soil biota in managed grasslands systems". Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7844.
Pełny tekst źródłaStreszczenie:
The application of phosphorus (P) fertilisers to grassland systems is a common practice to increase and sustain grassland productivity. This is requisite for satisfying the nutritional needs of grazing animals and increasing dairy and livestock output. The costs of such fertilisers are increasing and the demands for such fertiliser will also most likely rise following governmental targets set in Ireland to increase national agricultural output. However, the application of P fertiliser to grassland systems can contribute to the eutrophication of water-courses, since fertiliser applications can result in the accumulation of P at the soil surface. One potential way to facilitate plant P acquisition in grasslands may be associated with the soil biota. In particular, the soil microbial biomass is recognised as a potential P pool that can provide a source of bioavailable P to the plant community. The soil biota may also facilitate the incorporation of P from the soil surface into the soil profile, since earthworms can actively increase the transport of P-rich soil material from the surface belowground. This project thus aimed to discern how P fertilisation affects microbial biomass nutrient pools and biologically-mediated P incorporation in grassland systems, and how this relates to plant P yields. To investigate this aim, two research questions were proposed: (i) is the soil biota affected by commonly adopted P fertiliser strategies in grassland systems?; (ii) what consequence does this hold for P acquisition by the plant community? An experiment was conducted to examine how the soil biota responded to different rates of inorganic P fertilisation in two grassland sites of contrasting soil types over an 18 month period. This revealed that increasing P fertilisation did not affect microbial biomass P concentrations in the soil. However, an effect was observed upon plant P yield, in which greater plant P yields were obtained proportional to the P fertiliser rate. Two laboratory experiments were conducted to further investigate this lack of effect. These utilised soil from the same grassland sites and examined how nutrient additions to the soil affected microbial biomass nutrient pools and activity. Results from these experiments supported evidence from the field experiment, since the application of P fertiliser did not affect microbial biomass nutrient pools following fertiliser application, and supplementation of carbon (C) + P substrate to the soil did not invoke respiratory responses between P fertiliser treatments. Nevertheless,supplementation with C + nitrogen (N) and C+N+P substrates was found to suppress microbial respiration. This was attributed to greater C assimilation by the microbial community in these particular substrate-induced respiration treatments. In order to investigate biologically-mediated P incorporation, a glasshouse-based mesocosm scale experiment was carried out using two contrasting soils. Bulk soil (1 – 30 cm depth range) was derived from a nutrient poor grassland system, whereas the soil for the 0 – 1 cm depth range was taken from an intensive system that was seven times greater in labile inorganic P concentration. Three treatments were applied to mesocosms in an incomplete factorial design, involving the inclusion of earthworms, different botanical diversities (unplanted, monoculture or mixed plant community) and different fertiliser types (organic or inorganic). The absent factorial combinations involved the application of earthworms to unplanted mesocosms. With respect to the earthworm treatment, results revealed that the presence of earthworms reduced labile P concentrations in the 0 – 1 cm depth range of soil. The presence of different botanical diversities or fertiliser types did not affect microbial biomass nutrient pools, whilst the presence of mixed plant communities did increase plant P yields. However, microbial and nematode community structures were affected in an idiosyncratic manner by both botanical diversity and fertiliser type. This project demonstrated the significance of grassland management regimes in governing microbial biomass P concentrations. In particular, it was revealed that the frequent defoliation of the sward appeared to uncouple the microbial community from both fertiliser inputs and possibly plant P yields. The fact that an increase in plant P yield with increasing P fertilisation was noted in the absence of microbial responses suggests that the soil biota may not be crucial for plant P acquisition in such intensive inorganic-fertiliser based regimes. This suggestion was also supported by the mesocosm experiment, since plant P yields differed between botanical diversities but no effects were observed on microbial biomass P concentrations. Furthermore, this project showed the potential of the earthworm community to reduce P concentrations in the volume of soil which poses the greatest risk to water quality. The collective evidence highlights the need for further understanding of the consequences of inorganic-based fertiliser management systems, since current strategies may not adequately account for management effects on soil biological P cycling.
43
Simpson, Julia Louise. "Male gamete morphology in relation to swimming velocity and fertilisation microenvironment". Thesis, University of Hull, 2012. http://hydra.hull.ac.uk/resources/hull:6900.
Pełny tekst źródłaStreszczenie:
The heterogeneity of spermatozoa has been widely used to inform phylogenetic relationships among taxa, yet the reason such diversity has evolved, in relation to the sperms primary functional role in fertilisation and reproduction, is not well understood. Research into the evolutionary significance of sperm morphology is concomitant with the study of sexual selection and the evolution of the biological diversity of life. The formulation of sperm competition theory in the 1970s provided a new insight for the study of sexual selection and the development of the field of sperm biology. The idea that males not only competed for access to females but that, through direct competition, spermatozoa of individual males were also in competition to fertilise the maximum number of eggs was a revolutionary concept. An integral part of many sperm competition models is the assumption that there is a relationship between sperm morphology and swimming velocity in terms of fertilisation success. In addition to this it is further assumed that longer sperm swim faster than shorter sperm. During competitive mating, when the ejaculate from two or more males compete to fertilise a given set of eggs, longer and therefore faster, sperm should have a fertilisation advantage as they can reach and fertilise eggs first. However identifying the traits that make individual sperm more or less capable of successfully fertilising an egg remain largely unknown for most species. There has so far been little empirical support for a link between sperm morphology and swimming speed and mixed results regarding the importance of swimming speed when it comes to increasing fertilisation success. Here, three aspects of sperm biology were investigated in order to clarify functional links between sperm morphology and velocity. Firstly, the influence that female gametes have on the swimming behaviour of both fresh and cryopreserved bovine sperm was examined. Bovine samples were used because it is known that in the bovidae family, female gametes release chemoattractans which appear to play a role in sperm guidance towards the oocyte (egg). Additionally, a large literature base regarding damage caused by cryopreservation of bovine sperm exists. The second topic of research focuses on cichlid fish. Cichlids from Lake Malawi have been underrepresented in the published literature in sperm biology despite being extensively studied in relation to other aspects of their biology. A phylogenetically controlled study into links between sperm morphology and velocity across mouthbrooding cichlids from Lake Malawi was therefore undertaken. All endemic cichlids in Lake Malawi are maternal mouthbrooders in which the female broods both eggs and fry inside her buccal cavity (a cavity inside the mouth of the female between the jaw and cheek). The functional significance of the buccal cavity is also important as the point of fertilisation for some species. Variation in sperm length has been found in cichlid species in Lake Tanganyika where substrate fertilisers have significantly longer sperm than species fertilising inside the buccal cavity. However, links between morphology and velocity have found little support when using traditional methods that rely on the calculation of mean measurements of sperm morphology and velocity. Here an experimental approach focusing on measurements from individual sperm whilst accounting for within-male variation was employed to investigate the extent to which links between sperm morphology and velocity to be revealed across species. The third area expands on the idea that fertilisation point will have an influence on sperm form and function and compares sperm data from three internally and three externally fertilising species. Once again measurements from individual sperm were used and within-male variation was included in the analysis. The influence of chemoattractants on sperm swimming speed and direction are frequently omitted in the sperm competition literature, as are comparisons of the effects of sperm preservation methods such as cryopreservation. Such considerations are, in a large part left to articles on animal breeding and artificial insemination. It is however, widely acknowledged that chemoattractans do influence sperm motility in a range of taxa and that cryopreservation damages sperm. Whilst chemotaxis in bovine sperm was not detected in this study, variation in swimming characteristics of bovine sperm related to the method of preservation was observed. As cryopreservation appears to alter sperm behaviour it seems unlikely that observations of swimming velocity of fresh and cryopreserved sperm can be compared when considering relationships between sperm length and velocity. Information from both fresh and cryopreserved sperm is useful when considering links between sperm traits and fertilisation success but need to be considered independently. Using comparative methods to investigate sperm traits across closely related species of cichlid fish no phylogenetic correlation for sperm traits was found. Furthermore, sperm morphology did not show any correlation with velocity across species. However, when within-male variation was accounted for, a relationship between sperm morphology and velocity was revealed. Interestingly the relationship was frequently a negative one, a novel finding despite numerous studies into sperm morphology-speed relationships. When the results from data comparing internal and externally fertilising species was considered negative relationships tended to be more prevalent in internally fertilising species. If this is a general trend, that shorter sperm swim faster in internally fertilising species, we could extrapolate that the negative relationships between sperm length and velocity found in the cichlid data set exhibit sperm morphology adapted for internal fertilisation. A larger sample size would be required to conclusively support this suggestion that could confirm Lake Malawi cichlids share a common point of fertilisation, within the buccal cavity, despite high levels of diversity found in other aspects of the speciation of these cichlids. The findings of the work presented here highlight the negative influence cryopreservation has on sperm motility and that measurements of individual spermatozoa are vital if links between morphology and velocity are to be detected. The importance of sperm preservation method on the swimming behaviour, and by association the ability of the individual sperm to successfully complete fertilisation, requires further investigation to link the morphology and velocity of individual sperm to the method of preservation. This link would provide valuable insight into the structure of sperm subpopulations which are the most resistant to cryopreservation and therefore of most value for techniques such as artificial insemination. Using a new method for measuring individual sperm morphology and velocity whilst accounting for intra-male variation significant links between sperm morphology and velocity in a number of vertebrates and invertebrates were revealed. The data gathered here suggests that such links could be widespread across more species than current empirical work indicates. Furthermore, the direction of relationships between morphology and velocity appear to be revealing disparity between internally and externally fertilising species.
44
Sanders, Jessica Rose. "Mechanisms of PLCζ induced Ca²⁺ oscillations in mouse eggs at fertilisation". Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/103822/.
Pełny tekst źródłaStreszczenie:
All the events of egg activation in mammalian eggs are triggered physiologically by transient increases in cytosolic free Ca²⁺ referred to as Ca²⁺ioscillations. These oscillations are initiated by the sperm derived PLC isoform, PLCζ. PLCζ releases Ca²⁺ by hydrolysing its substrate PI(4,5)P₂ to produce IP₃, however, many of the mechanisms by which PLCζ elicits Ca²⁺release in eggs are poorly understood. The results of this thesis confirm that whilstPLCζ cRNA and recombinant protein is able to cause Ca²⁺ioscillations in mouse eggs the sperm derived protein PAWP does not cause any Ca²⁺ release in any circumstances. It is shown that EF hand domain and XY linker of PLCζ are important in determining its Ca²⁺i releasing ability by enabling PLCζ binding to its substrate PI(4,5)P₂ through electrostatic interactions. The C2 domain of PLCζ was also found to play a crucial role in the Ca²⁺ releasing ability of PLCζ, possibly by binding to lipids or proteins in the target membrane. The Ca²⁺releasing ability of eggs is acquired during oocyte maturation and a dramatic increase in PLCζ sensitivity of oocytes occurs after germinal vesicle breakdown. A variety of markers for PLCζ’s substrate PI(4,5)P₂ including fluorescent PI(4,5)P₂ and gelsolin based fluorescent probes suggests that this PI(4,5)P₂ is localised to intracellular vesicles that could derive from Golgi apparatus. Attempts are made to measure PI turnover in these intracellular compartments of eggs during PLCζ induced Ca²⁺i oscillations using several probes. The results of this thesis suggest that PLCζ releases Ca²⁺ by a novel IP₃ based signalling pathway that involves an intracellular source of PI(4,5)P₂.
45
Goubier, Vincent. "Influence de la fertilisation sur certains compartiments de l'étang de pisciculture". Lyon 1, 1989. http://www.theses.fr/1989LYO10043.
Pełny tekst źródłaStreszczenie:
Ce travail est une approche de la constitution et de l'evolution des differents compartiments de l'etang, en relation avec une fertilisation minerale ou organique, dans des bassins de pisciculture semi-intensive. 6 a 16 bassins, de 500 a 1500 m#2, situes dans la region de dombes (france), sont suivis pendant 4 saisons de production. Les principales variables physico-chimiques etudiees sont: la temperature, le ph, les formes azotees, le phosphore, les parametres de mineralisation. Une etude ponctuelle concernant les relations physico-chimiques entre l'eau et le sediment a ete realisee en 1984. Pour le compartiment vegetal, le phytoplancton est suivi quantitativement par le biais de la concentration en pigments chlorophylliens et fait l'objet de plusieurs determinations quantitatives. Des etudes ponctuelles sont realisees sur le periphyton et les macrophytes. Le zooplancton est evalue par la determination des abondances absolues et relatives des familles de crustaces. La fertilisation phosphatee permet une stimulation du compartiment phytoplanctonique, qui se repercute sur les consommateurs primaires et secondaires, dans la mesure ou le reseau trophique le permet. En effet, de nombreux blooms algaux a cyanophycees, constituant des impasses trophiques pour le systeme, sont observes dans les bassins, en liaison presumee avec des desequilibres chimiques. De ce fait, les productions piscicoles obtenues, qui atteignent 540 kg/ha (carpe et tanche), ne sont pas toujours correlees a la fertilisation minerale ou organique apportee. Du point de vue methodologique, ce travail montre les limites et les apports d'une etude systemique pour la connaissance de l'ecosysteme etang
46
Dalati, Sarah. "Ca2+ activated CI- channel activity at fertilisation in the mouse oocyte". Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14481.
Pełny tekst źródłaStreszczenie:
Sperm entry into the oocyte triggers a signal transduction pathway that results in intracellular calcium ([Ca2+]i) oscillations and membrane potential (Em) changes known as hyperpolarisations. [Ca2+]i oscillations have been widely studied and are important for embryo development. The role of Em hyperpolarisations and their importance at fertilisation remains unclear. Thimerosal, a sulfhydryl reagent, has been shown to mimic the physiological changes caused by sperm following fertilisation. Previous patch clamp analysis of unfertilised mouse oocytes has shown that thimerosal elicits simultaneous Em hyperpolarisations and [Ca2+]i oscillations. It has been recently discovered that the TMEM16A protein forms CaCC’s in Xenopus oocytes where it induces changes in Em. We hypothesise that changes in Em following fertilisation may be due to the activation of Ca2+ activated Cl- channels (CaCC) present in the membrane of mouse oocytes. This study aims to determine the expression of these ion channels in mouse oocytes and embryos, to assess their role in fertilisation and identify whether TMEM16A maybe a possible candidate for CaCC’s. The thimerosal induced Em and [Ca2+]i changes were inhibited by the CaCC blockers, DIDS and NFA and the specific CaCC inhibitor T16Ainh-A01. In vitro fertilisation studies showed that the KCa channel blocker tetraethylammonium (TEA), and voltage gated Cl- channel blocker 9AC had no effect on fertilisation rates but there was a significant reduction in the percentage of oocytes that fertilsed in the presence of the CaCC inhibitors DIDS and T16Ainh-A01 Culturing zygotes in the presence of T16Ainh-A01 (10 μM) completely inhibited their cleavage to the 2-cell stage. Furthermore, western blot analyses showed that TMEM16A is expressed at higher levels from the oocyte to 8-cell stage mouse embryo, but reduced in the morula and blastocyst stages. In conclusion these data show that the activation of a CaCC channel may play an important role in initiating the cellular events that occur during fertilisation and early cell division and that TMEM16A may be a possible candidate in forming this channel.
47
Joels, Lisa Anne. "The predictive value of sperm assessment prior to in vitro fertilisation". Thesis, University of Bristol, 2000. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310655.
Pełny tekst źródła
48
He, J. "A study of the morphological characteristics of rat ovarian granulosa cells during maturation of the oocyte". Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239005.
Pełny tekst źródła
49
Henderson, Janet Katharine. "Investigations of human embryonic implantation in vitro". Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341905.
Pełny tekst źródła
50
Fayolle, Adeline. "Structure des communautés de plantes herbacées sur les Grands Causses : stratégies fonctionnelles des espèces et interactions interspecifiques". Montpellier SupAgro, 2009. http://www.theses.fr/2009NSAM0013.
Pełny tekst źródłaStreszczenie:
La réponse des communautés de plantes herbacées à la gestion du pâturage a été étudiée sur le domaine INRA de La Fage, Causse du Larzac. L’intensité de l’utilisation des terres est vue comme un filtre de perturbation et de ressource qui trie les espèces. Les traits fonctionnels sont placés au cœur d’une approche intégrée de l’étude de la structure des communautés. Les variations continues des traits liés à l’acquisition des ressources et à une phénologie précoce traduisent le remplacement d’espèces tolérantes au stress par des espèces rudérales, le long du gradient d’intensité d’utilisation (évitement du pâturage). Les espèces graminoÉides sont présentes et particulièrement abondantes tout le long du gradient d’intensité d’utilisation des terres. Les changements d’identité des espèces et d’identité fonctionnelle reflètent néanmoins des différences de tolérance au pâturage entre ces espèces. A l’échelle de la communauté, la forte convergence fonctionnelle de ces traits confirme l’effet « filtre » des pratiques de gestion sur les espèces dominantes. Par ailleurs, la richesse spécifique est maximale pour des niveaux intermédiaires de pâturage. Elle est associée à la coexistence de plusieurs types biologiques et à une forte richesse fonctionnelle. Ces résultats sont interprétés comme une extension de l’hypothèse de perturbation intermédiaire aux traits des espèces coexistantes. Enfin, l’étude de la dynamique des interactions entre plantes expérimentées par cinq espèces cibles a permis d’identifier i) une tendance à la facilitation de la survie, et ii) une intense compétition pour la biomasse liée à la croissance des voisins. Si l’effet des communautés de structure spécifique et fonctionnelle contrastée est similaire, la réponse des espèces cibles dépend fortement de l’identité de l’espèce, et de la phénologie. Les espèces les plus précoces souffrent le moins de la compétition et bénéficie le plus de la facilitation.