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Heeg, Daniela. "Spore formation and spore germination of Clostridium difficile." Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.594825.
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Clostridium difficile is the major underlying cause of antibiotic-associated diarrhoea and poses a risk for healthcare systems worldwide. Endospores produced during sporulation are widely regarded to be the infectious agent of C. difficile associated diarrhoea. These spores are able to withstand a variety of antimicrobial agents and industrial cleaning products and are therefore able to reside on surfaces in healthcare settings for prolonged periods of lime. In order to cause disease in susceptible individuals, spores need to abjure dormancy and return to vegetative cell growth through germination. Sporulation and germination have been studied extensively in Bacillus spp. Knowledge about the sporulation and germination pathways in C. difficile, however, remains incomplete. Here, forward and reverse genetics methods were employed to analyse sporulation and germination phenotypes of C. dfficile. Using forward genetics, 19 mutants with potential sporulation and/or germination phenotypes were isolated, three of which were completely deficient for sporulation. In an attempt to explore the use of transposon suicide vectors, a protocol for the successful transformation of C. difficile was developed. A reverse genetic mutant in the germination specific lytic transglycosylase Slee created by ClosTron mutagenesis was used to study spore germination in vivo. This study is the first report of the use of a germination mutant in vivo. The sporulation characteristics of 52 clinical C. difficile isolates have been analysed indicating that a variation in the rate of sporulation is not associated with molecular type. The germination characteristics of 37 clinical C. difficile isolates were examined, indicating that different isolates exhibit varying germination characteristics in response to bile salts.
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Eke, Milton Adams. "Spore-dome actinomycetes." Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292687.
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PORTINHA, Inês Cunha. "Exploring the evolutionary link between biofilms and spores formation in spore-formers." Master's thesis, Instituto de Higiene e Medicina Tropical, 2015. http://hdl.handle.net/10362/19323.
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Bacteria are often thought as single cell organisms, however they can develop into morphologically complex multicellular communities composed of different subpopulations of specialized cell types. Biofilm is an example, in which bacteria organize for protection from harmful conditions in the host and to create nutrient-rich areas. In the last years biofilm have been show to comprise an important aspect of microbial persistence in the human gut. Endospore-formers, although thought not to be major constituents of the microbiota in the human intestine, cause several intestinal diseases, usually associated with antibiotic use. Whether these bacteria persist in the intestine in biofilms or as endospores is not totally elucidated since both, biofilms and endospores, are able to resist to antimicrobial agents. Most likely sporulation and biofilm formation are tightly linked processes. For some endosporeformers, spore differentiation is induced by a sub-population of cells within the biofilm.
In this work we tackled the link between bacterial biofilms and endosporulation in Bacillus subtilis. We showed that endospores produced in biofilms have higher resistance to UV radiation. We revealed that a gene, remA, conserved among endosporeformers and essential for biofilm formation is expressed during sporulation. remA is expressed in the forespore soon after asymmetric division and in the mother cell after engulfment completion. GerE represses remA expression in the mother cell at late stages of sporulation. Consequently, we found components of the biofilm matrix, TasA and BslA, on the coat of endospores produced in biofilms. We suggest that components of the biofilm matrix may be part of mature endospores. We hypothesize that some of the structural proteins that confer integrity to the matrix biofilm, as TasA, may have a role as a scaffold for the assembly of the endospore surface layers.A percepção instalada é a de que as bactérias são organismos unicelulares. No entanto, estes organismos são capazes de se organizarem em comunidades multicelulares complexas compostas de subpopulações de células diferenciadas. Os biofilmes são um exemplo deste tipo de organização. Os biofilmes conferem protecção contra as condições desfavoráveis encontradas no hospedeiro, ao mesmo tempo que criam nichos ricos em nutrientes facilitando a implantação da população. Nos últimos anos foi demonstrado que a persistência microbiana no trato gastrointestinal humano se deve em larga medida à formação de biofilmes. Algumas bactérias que podem ser encontradas no trato gastrointestinal humano são ainda capazes de diferenciar um tipo celular altamente resistente a insultos químicos e físicos, o esporo. Nestes casos, não é claro se são os biofilmes ou os endoesporos os principais responsáveis pela persistência destes organismos, já que ambos são resistentes aos antibióticos. Neste trabalho exploramos a ligação genética entre a formação de biofilmes e a esporulação em Bacillus subtilis. Mostramos que os endoesporos produzidos em biofilmes exibem maior resistência aos UV. Mostramos que um gene, remA, conservado em bactérias formadoras de endoesporos e essencial para a formação de biofilmes é expresso durante a esporulação. remA é expresso no pré-esporo após a divisão assimétrica e na célula mãe após o envolvimento do pré-esporo. GerE reprime a expressão de remA na célula mãe em estádios tardios de desenvolvimento. Consequentemente, encontramos componentes da matriz do biofilme no manto de endoesporos maduros. Algumas das proteínas estruturais que conferem integridade à matriz do biofilme, como TasA, poderão servir como base para a montagem das camadas superficiais do esporo.
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Swiecki, Melissa K. "Bacillus anthracis spore-host interactions." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2007. http://www.mhsl.uab.edu/dt/2007p/swiecki.pdf.
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Chen, Yan. "Characterization of Bacillus Spore Membrane Proteomes and Investigation of Their Roles in the Spore Germination Process." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64934.
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Components of the bacterial spore germination apparatus are crucial for survival and for initiation of infection by some pathogens. While some components of the germination apparatus are well conserved in spore-forming species, such as the spoVA operon, each species may possess a different and possibly unique germinant recognition mechanism. The significance of several individual proteins in the germination process has been characterized. However, the mechanisms of how these proteins perform their functions and the network connecting these proteins in the complete germination process are still a mystery.
In this study, we characterized a Bacillus subtilis superdormant spore population and investigated the abundance of 11 germination-related proteins. The relative quantities of these proteins in dormant, germinating and superdormant spores suggested that variation in the levels of proteins, other than germinant receptor proteins may result in superdormancy. Specifically, variation in the abundance of the GerD lipoprotein may contribute to heterogeneity of spore germination rates.
Spore membrane proteomes of Bacillus anthracis and B. subtilis were characterized to generate a candidate protein list that can be further investigated. Proteins that were not
previously known to be spore-associated were identified, and many of these proteins shared great similarity in both Bacillus species. A significant number of these proteins are implicated in functions that play major roles in spore formation and germination, such as amino acid or inorganic ion transport and protein fate determination.
By analyzing the in vivo and in vitro activity of HtrC, we proved that the protease is responsible for YpeB proteolytic processing at specific sites during germination. However, without HtrC present in the spore, other proteases appear to degrade YpeB at a reduced rate. The activity of purified HtrC in vitro was stimulated by a relatively high concentration of Mn2+ or Ca2+ ions, but the mechanism behind the stimulation is not clear. We also demonstrated that YpeB and SleB, in the absence of their partner protein, were degraded by unknown proteases other than HtrC during spore formation. Identification and characterization of these unknown proteases would be a future direction for revealing the roles of proteases in spore germination.Ph. D.
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Hemsley, Alan Richard. "The ultrastructure of fossil spore exines." Thesis, Royal Holloway, University of London, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493795.
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Sangal, Abhishek. "STABILITY OF SPORE-BASED SENSING SYSTEMS." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_theses/4.
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The full exploitation of bacterial whole-cell biosensing systems in field applications requires the survival of bacterial cells and long term-preservation of their sensing ability during transportation and on-site storage of such analytical systems. Specifically, there is a need for rapid, simple and inexpensive biosensing systems for monitoring human health and the environment in remote areas which often suffer from harsh atmospheric conditions and inadequate commercial distribution and storage facilities. Our laboratory has previously reported the successful use of bacterial spores as vehicles for the long-term preservation and storage of whole-cell biosensing systems at room temperature.
In the present research, we have accomplished a year-long study to investigate the effect of extreme climatic conditions on the stability of spores-based whole-cell biosensing systems. The spores were stored in laboratory conditions that simulated those found in real harsh environments and germination ability and analytical performance of the spore-based sensing systems upon storage in such conditions was monitored. Our results proved that the intrinsic resistance of spores to harsh environmental conditions helped maintain the integrity of the sensor bacteria. The revived active cells actually retained their analytical performance during the course of the twelve-month storage study.
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Foster, S. J. "Biochemistry of Bacillus megaterium spore germination." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384466.
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Cai, Wen. "Production and applications of spore microcapsules." Thesis, University of York, 2014. http://etheses.whiterose.ac.uk/5896/.
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This thesis involves the preparation of exine shells derived from spores. The exines shells provide a ready source of microcapsules of uniform shape and monodispersed size in the region of 4 to 50 mm. The objective of the research was to fill the exine shells with various functional materials, and to examine qualitatively their bulk properties. Thus, the main production techniques and applications of sporopollenin microcapsules were extensively reviewed, with the objective of shortening the production process in order to develop commercial isolation techniques for sporopollenin exines. The conventional base and acid treatment was simplified and the microcapsules produced by this method were investigated detailed in order to evaluate the yield and quality of the exines. In order to demonstrate the utility of this procedure attempts were made to further simplify by shorter reaction time and limit chemicals applied. The overall result achieved was higher quality and useable exines, produced in a shorter time under less extreme conditions. The filling of exine microcapsules was studies for a range of materials including dyes and magnetic particles. It was found that, contrary to published data, it was possible to efficiently fill the microcapsules with an absorbate using a large volume of solvent. Dyes that were encapsulated enabled the demonstration of colour change through changes in pH and also temperature. Multicomponents system were also achieved which allowed the demonstration of multifunctionality such as colour and magnetic properties. The use of microcapsules in a chromatography or capture/release vehicle was also demonstrated.
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Jayaraman, Padmavathy. "Analysis of Bacillus subtilis 1604 spore germination." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317752.
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Hyde, K. D. "Spore settlement and attachment in marine fungi." Thesis, University of Portsmouth, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355131.
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Holmes, Phillip Lee. "An experimental approach to spore/pollen taphonomy." Thesis, Royal Holloway, University of London, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.734436.
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Stolze-Rybczynski, Jessica L. "Biomechanics of spore discharge in the Basidiomycota." Oxford, Ohio : Miami University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1249933181.
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Wan, Qiang. "Structure and assembly of Bacillus spore proteins." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/4161/.
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Jiang, Shuo. "Structure and assembly of Bacillus spore surfaces." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/9608/.
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Gupta, Srishti. "Molecular analysis of Bacillus megaterium spore germinant receptors." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708193.
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Meeske, Alexander Jacob. "Envelope biogenesis and spore formation in Bacillus subtilis." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493469.
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The bacterial cell wall exoskeleton (or peptidoglycan) protects cells from osmotic lysis, specifies their shape, and its biosynthetic pathway is a widely-exploited antibiotic target. My thesis research focused on defining how peptidoglycan synthesis is carried out in the model bacterium Bacillus subtilis.
My first project explored the transport of cell wall precursors across the lipid bilayer. The precursor lipid II is a lipid-anchored molecule synthesized on the inner surface of the membrane. In E. coli, trans-bilayer movement of lipid II requires the essential flippase MurJ. I discovered that B. subtilis can survive in the absence of its 10 MurJ homologs through an alternate and novel lipid II flippase called Amj. I demonstrated that Amj is upregulated in response to envelope stress, suggesting that it serves as a defense mechanism against environmental stressors or antibiotics.
My second project focused on the next step of the peptidoglycan biosynthesis pathway: the polymerization of lipid II into glycan strands. Polymerization is carried out by glycosyltransferases called class A penicillin-binding proteins (APBPs). In most bacteria, these enzymes are essential for viability, but they are dispensable in B. subtilis, implying the existence of an unidentified peptidoglycan synthase. I discovered that cells lacking these enzymes survive by upregulating a widely-conserved gene called rodA, whose homologs are essential for peptidoglycan assembly in virtually all bacteria. My biochemical analysis indicates that RodA has polymerase activity in vitro. Thus, B. subtilis, and likely most other bacteria, use two distinct mechanisms to synthesize their exoskeleton. RodA-like proteins represent appealing targets for broad-spectrum antibiotics.
Inspired by high-throughput genetic screens being developed in the lab, I undertook a separate project focused on the developmental process of spore formation in B. subtilis. Genetic screens have identified factors with roles in every step of sporulation. Using a transposon sequencing approach, I identified 24 new sporulation genes, in addition to virtually all of the 148 previously characterized loci. Phenotypic characterization of these mutants uncovered factors involved in diverse aspects of sporulation, including a novel intercellular signaling molecule. My results highlight the power of transposon sequencing, and could inspire similar screens for other developmental processes.Medical Sciences
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Silver, Sunshine Christine. "Kinetic, mechanistic and spectroscopic studies of spore photoproduct lyase." Diss., Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/silver/SilverS1210.pdf.
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Spore forming organisms are a health threat to humans and other animals in part due to a remarkable resistance to UV irradiation. This resistance results from two events: first, the formation of a unique thymine dimer, 5-thyminyl-5,6-dihydrothymine (spore photoproduct, or SP) upon UV irradiation; and more importantly, the rapid and specific repair of this DNA photoproduct to two thymines by spore photoproduct lyase (SP lyase). Understanding the molecular basis of this radical-mediated DNA repair will ultimately allow for a better understanding of how to address the health risks caused by spore forming bacteria. SP lyase requires S-adenosyl-L-methionine and a [4Fe-4S]¹+/²+ cluster to perform its catalysis. Presented in this work is a characterization of Clostridium acetobutylicm SP lyase and its ability to repair stereochemically defined dinucleoside and dinucleotide synthetic substrates. Careful synthesis and characterization followed by assays monitored by HPLC indicate SP lyase repairs only the 5R isomer of SP with an activity of 0.4 nmol/min/mg (dinucleoside substrate) and 7.1 nmol/min/mg (dinucleotide substrate). These results support the longstanding theory of SP formation by dimerization of adjacent thymines in double-helical DNA. Kinetic and mechanistic studies were pursued to further elucidate the mechanism of SP repair. Upon pre-reducing SP lyase, the specific activity increased nearly 4-fold to 1.29 μmol/min/mg. Mechanistic studies utilizing [C-6-³H] SP DNA as the substrate revealed a primary tritium kinetic isotope effect of 16.1, indicating a rate determining step during the repair reaction. These results suggest nonstereospecific SP formation regarding the C-6 position and subsequent stereospecific abstraction of the C-6 H atom by SP lyase. Mossbauer and Fe/S K-edge X-ray absorption studies of anaerobically prepared SP lyase aided in further characterization of the [4Fe-4S] cluster and its interaction with SAM. The Fe K-edge EXAFS provide evidence for a slight cluster distortion upon interacting with SAM as a new spectral feature indicative of longer Fe-Fe distances is observed. The Fe K-edge XANES provide further support that SAM is not undergoing reductive cleavage in the presence of reduced SP lyase. Our XAS studies may provide new insights into the mechanism by which radical SAM enzymes initiate their diverse catalysis.
'Co-authored by Tilak Chandra, Egidijus Zilinskas, Eric M. Shepard, William E. Broderick, Joan B. Broderick, Shourjo Ghose, Jeffrey M. Buis, David J. Gardenghi, BoiHanh Huynh, and Robert K. Szilagyi.'
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Zilinskas, Egidijus. "Binding and repair of DNA by spore photoproduct lyase." Thesis, Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/zilinskas/ZilinskasE0510.pdf.
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Bacterial spores are extremely resistant to chemical and physical stresses, including UV irradiation, which in spores results in the formation of 5-thyminyl-5,6-dihydrothymine (spore photoproduct, SP). While SP accumulates in UV-irradiated bacterial spores, it is rapidly repaired during germination. Spore photoproduct lyase (SPL) is the enzyme that catalyzes the specific repair of spore photoproduct to two thymines. It utilizes S-adenosylmethionine (SAM) and a [4Fe-4S] cluster to catalyze this reaction, and is a member of the radical SAM superfamily. Presented here is an investigation of SPL repair activity towards stereochemically-defined synthetic R- and Sspore photoproduct dinucleosides and dinucleotides (SP and SPTpT, respectively), utilizing SPL purified from Clostridium acetobutylicum. The results of HPLC and Mass Spectrometry analysis of in vitro enzymatic assays demonstrate that SPL specifically repairs the 5R-, but not the 5S- isomer. The repair rates were determined to be ~0.4 nmol/min/mg of SPL for the 5R-SP dinucleoside and ~7.1 nmol/min/mg of SPL for the 5R-SPTpT dinucleotide. Since SPL binding to DNA is a key step in UV damage repair, SPL binding to undamaged DNA, as well as the 5R- and the 5S-isomers of SP and SPTpT, was also investigated. The binding to different substrates was investigated by carrying out electrophoretic mobility shift assays (EMSA) and time-resolved fluorescence decay experiments. SPL from both Bacillus subtilis and Clostridium acetobutylicum cooperatively binds the undamaged DNA with relatively high affinity (Kd = 4.7 x 10 â»â¹ M for B.s. SPL and Kd = 1.7 x 10 â»â· M for C.a. SPL). The presence of small, acid-soluble proteins (SASP), SAM or the [4Fe-4S] cluster of SPL have little effect on SPL binding to undamaged DNA. Interestingly, SPL is able to bind both the 5R- and the 5S- diastereomers of the synthetic dinucleoside/dinucleotide spore photoproduct, although only the 5R-isomer is repaired. SP lyase binding is stronger to the SPTpT dinucleotide than to the SP dinucleoside, likely due to the dinucleotide more closely resembling the natural substrate in double helical DNA. Also, SPL exhibits higher affinity towards SP and SPTpT than the repair products, thymidine or thymidylyl (3'-5') thymidine (TpT), respectively.
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Burns, David Alexander. "Analysis of the spore germination mechanisms of Clostridium difficile." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/11852/.
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Clostridium difficile is the leading cause of hospital acquired diarrhoea and a major burden to healthcare services worldwide. Endospore production plays a pivotal role in infection and disease transmission, but in order to cause disease these spores must germinate and return to vegetative cell growth. Therefore, knowledge of spore germination is important and may have direct applications in future disease prevention. Germination has been well studied in Bacillus and in some clostridia, but the mechanisms of C. difficile spore germination remain unclear. Apparent homologues of genes important for germination in other spore formers have been identified in the C. difficile genome and ClosTron technology was used to inactivate homologues of sleC, cspA, cspB and cspC (Clostridium perfringens) and cwlJ, sleB and cwlD (Bacillus subtilis) in both C. difficile 630Δerm and a BI/NAP1/027 isolate (a ‘hypervirulent’ type associated with outbreaks of increased disease severity). Using a combination of several different assays to study these mutants in detail, a number of the identified target genes appear to be essential for germination and outgrowth of C. difficile spores. This is the first report of using reverse genetics to study the germination of C. difficile spores and the first gene characterisation by mutagenesis in a BI/NAP1/027 isolate of C. difficile. Furthermore, this study uncovered evidence of significant variation in the sporulation and germination characteristics of different C. difficile strains, but this variation did not appear to be type-associated.
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Kirsten, Johanita. "Laaste spore van Nederlands in Afrikaanse werkwoorde / J. Kirsten." Thesis, North-West University, 2013. http://hdl.handle.net/10394/10193.
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In the diachronic studies of Afrikaans in the past, the focus used to be on the origin and early development of Afrikaans from Dutch. During the twentieth century, the philological school, with a tradition of researching all Cape-Dutch coloured texts in detail, was established through the work of J. du P. Scholtz and his students. Through their analyses, they estimated the stabilisation of Afrikaans as early as the end of the eighteenth century (for example Raidt, 1991:145; Ponelis, 1994:229). In the past few decades, however, this estimation has begun to receive criticism from other scholars, including Roberge (1994:159) and Deumert (2004:20). With the help of a corpus, Deumert (2004) has shown that there is substantial variation in Afrikaans letters as late as the early twentieth century, and this study expands on her work by researching the variation in published writing. This is done by focusing on verbs, as there is significant change from the Dutch verbal system to the Afrikaans verbal system. This study uses corpus linguistic research methods, and researches Dutch-Afrikaans variation in verbs in published Afrikaans texts, compiled in three corpora. The main corpus was compiled from all the Afrikaans writings of Totius (J.D. du Toit) in the publication Het Kerkblad from 1916 to 1922. Two control corpora are also used: the first was compiled from excerpts from published Afrikaans books for the same period, and the second was compiled from excerpts from Afrikaans periodicals for the same period. In order to compensate for the shortcomings of corpus data alone, normative works on Afrikaans from the relevant period are also taken into account, and there is shown which recommendations these works made about the relevant constructions, and how the corpus data correlates with these recommendations. Variation in six verbal constructions are analysed in this study: 1. End consonant t/n (for example gaat/gaan): the old (more Dutch) word forms are scarcely used in the corpora, while the modern Afrikaans word forms are almost fully established. 2. End consonant g (for example seg/sê): the old word forms are also scarcely used in the corpora, while the modern word forms take the lead. 3. Stem vowel (for example breng/bring): the old word forms are more frequent at the beginning of the period, followed by some uncertainty, with the modern word forms taking over by the end of the period. 4. Preterite (specifically had/gehad and werd/geword): there is great instability throughout, worsened by a distinction in use between main verbs and auxiliary verbs made by some authors. 5. Past participle (for example gedaan/gedoen): there is significant instability at the beginning of the period, but the modern word forms are used more frequently by the end of the period. 6. Perfect tense auxiliary verb (is/het): the old form is still used in the corpora, but the modern form is more frequent from the beginning, and becomes even more frequent towards the end. This data shows that there was still significant variation in Afrikaans under Dutch influence as late as the early twentieth century, and the correlation between the different corpora implies that the written language might have been much closer to the spoken language than had been previously assumed. It is further confirmed by the amount of attention this variation gets in the normative works from that period.Thesis (M.A. (Afrikaans and Dutch))--North-West University, Vaal Triangle Campus, 2013
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Nielsen, Preben. "Characterization and classification of alkaliphilic spore-forming aerobic bacteria." Thesis, Heriot-Watt University, 1994. http://hdl.handle.net/10399/1338.
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Mongkolthanaruk, Wiyada. "Functional analysis of spore germination proteins of Bacillus subtilis." Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444580.
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Üstok, Fatma Işık. "Molecular analysis of Bacillus Megaterium spore cortex lytic enzymes." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608139.
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Atkinson, Helen A. "Spore germination in the rice blast fungus, Magnaporthe grisea." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/13651.
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One of the major aims of the study was to characterise spore germination using light microscopy and to investigate the role and relative importance of each of the three conidial cells for successful germination. Analysis of germ tube growth rate showed that there are two modes of germination: a conidium produces either a single germ tube or two slightly slower growing germ tubes. Results from scanning electron microscopy and fluorescence microscopy studies suggest that germ tube emergence is asymmetric and directed towards the substratum. A method was developed by which individual conidial cells could be selectively killed, using localised laser irradiation, a technique which has not been previously used with fungal cells. The data suggest that isolated apical and basal cells are able to germinate and form appressoria. The middle cell never germinated, even when it was the only living cell in a conidium. Furthermore, there was evidence that the apical cell, which germinates most frequently, exerts "apical dominance" over the basal cell. Very little is known about organelle morphology and distribution within living fungal spores, and even less is known abut organellar dynamics during spore germination. Another major aim of this study was to characterise organellar organisation and dynamics in living and potentially pathogenic conidia throughout germination. The analysis used confocal microscopy and vital stains. To obtain biologically meaningful results, an in vitro system which mimicked in vivo conditions as closely as possible was developed and optimised for confocal microscopy. A range of potentially vital dyes were screened as organelle stains in living conidia during germination. Nuclei (stained with SYTO 11), vacuolar compartments (stained with cDFFDA), mitochondria (stained with Rhodamine 123), and the apical vesicle cluster (stained with FM4-64) were identified and characterised during germination. Each cell was shown to contain a single nucleus that changed position within the cell during germination but otherwise did not exhibit extensive movement.
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Meador-Parton, Jennifer L. "Structural Analysis of Bacillus subtilis Spore Peptidoglycan During Sporulation." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/30922.
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Bacterial spore peptidoglycan (PG) is very loosely cross-linked relative to vegetative PG. Theories suggest that loosely cross-linked spore PG may have a flexibility which contributes to the attainment of spore core dehydration. The structure of the PG found in fully dormant spores has previously been examined in wild type and many mutant strains. These analyses showed little correlation between the degree of spore PG cross-linking and core dehydration. However, these studies only examined the structure of PG from dormant spores and did not allow for the structural analysis of spore PG during sporulation when actual spore PG synthesis and core dehydration occur.
Structural analyses of developing spore PG from wild type Bacillus subtilis and eight mutant strains are included in this study. Structural analyses of developing spore PG suggest the following: a) the germ cell wall PG is synthesized first next to the inner forespore membrane; b) cross-linking is relatively high in the first 10% of spore PG synthesized; b) a rapid decrease in cross-linking is observed during synthesis of the next 20% of the spore PG; and c) this decrease is followed by an eightfold rise in the degree of cross-linking during synthesis of the final 70% of the spore PG. This increasing gradient of cross-linking was previously predicted to contribute to the attainment of spore core dehydration. However, analyses of mutant strains indicate this cross-linking gradient is not required for the attainment of spore dehydration.Master of Science
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Ridsdale, Carmen Jane. "Interactions of arbuscular mycorrhizal fungi and spore-associated bacteria." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1018269.
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Arbuscular mycorrhizal (AM) fungi are naturally occurring in roots of terrestrial plants. AM fungi are capable of benefiting the host plant through various mechanisms such as enhanced nutrient supply, alleviation of environmental stress and inhibition of plant fungal pathogens. AM fungal spore-associated bacteria have been previously isolated and shown to have plant growthpromoting (PGP) abilities by several authors. Some bacterial isolates are able to promote AM fungal colonisation of host plants and are known to be mycorrhizal helper bacteria (MHB). This study focused on the isolation of AM fungal spore-associated bacteria, characterization of the isolates according to plant growth promoting abilities and evaluation of their potential to enhance plant growth and mycorrhizal colonisation. AM fungi were extracted from soils sampled from natural indigenous forest sources, raspberry (Rubus idaeus cv. Heritage) and strawberry (Fragaria ananassa) farms in South Africa and from a raspberry (Rubus idaeus cv. Autumn Bliss) plantation in Argentina. A total of 52 sporeassociated bacteria were isolated from the external and internal surfaces of AM fungal spore morphotypes from the two countries. The bacterial isolates were evaluated for their PGP abilities such as phosphate solubilisation, indole-3-acetic acid production, ammonia production and inhibition of the fungal pathogens Fusarium oxysporum and Phythophthora nicotianae through mechanisms such as siderophore and/ or hydrolytic enzyme production. A total of 23 bacterial isolates from both South Africa and Argentina showing the most potential to be PGP, were identified molecularly as belonging to the genera Acinetobacter, Alcaligenes, Bacillus, Microbacterium, Micrococcus, Serratia and Staphylococcus. The ability of ten selected bacterial isolates showing multiple PGP capacity were evaluated for their plant growth promotion and mycorrhizal colonisation enhancement ability on raspberry (Rubus idaeus cv. Meeker). Significant differences in increased shoot and root dry weights were shown by the treatments compared to the uninoculated control. The highest increase in shoot and root dry weights were shown by South African (Bacillus mycoides) and Argentinean (Alcaligenes faecalis) isolates. AM fungal colonisation was significantly enhanced by the South African (Bacillus mycoides) and Argentinean (Micrococcus luteus) isolates compared to the AM fungal singly inoculated control.
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Pratt, Michael D. "Differential response of various spore species to sporicidal disinfectants /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2068.pdf.
Full text
29
Wallace, Simon. "Evolutionary development of the plant spore and pollen wall." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/4681/.
Full text
30
Pratt, Michael David. "Differential Response of Various Spore Species to Sporicidal Disinfectants." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/1447.
Full textAbstract:
In the fall of 2001, letters laced with anthrax spores were delivered to various news organizations in New York and Florida, as well as to two Senators in Washington, D.C. Over 22 anthrax infections and five deaths resulted from exposure to these spores, and decontamination of the affected buildings was both time consuming and costly. Since these attacks, interest in sporicidal disinfectants has increased greatly. Many chemical sporicidal disinfectants are available commercially, but the exposure time required to sterilize can be relatively long. In addition, some spores are simply injured or inhibited by chemical disinfectants, but not necessarily killed. Studies have shown that heat shocking spores after exposure to some disinfectants can aid in the recovery of injured spores, but these studies have not evaluated this effect on spores exposed to peracetic acid-based disinfectants. Recently, our lab has evaluated two novel peracetic acid-based chemical disinfectants, PeraDox™ and PeraDox Ultra™ for their activity against a variety of bacterial agents. Results indicated that the PeraDox™ solutions had extremely rapid cidal activity on a wide variety of microorganisms, especially those with innate germicide resistance, such as bacterial endospores. However, possible recovery of these spores after heat shock was not evaluated. The purpose of this study was to compare the sporicidal activity of three disinfectants: CIDEX™, PeraDox™, and PeraDox Ultra™ on three species of spores (Bacillus subtilis, Bacillus anthracis, and Clostridium sporogenes) in suspension, with and without heat shocking. Spores in suspension were exposed to disinfectants for specified times and assayed for viable spores. These spore suspensions were then heat shocked (80 ºC for 20 min) and assayed again. After exposure to peracetic acid-based disinfectants and subsequent heat shock, some B. subtilis spores recovered, resulting in up to a one log difference in viable spores. Other species and disinfectants did not show this effect. In addition, the activity of these disinfectants on spores dried onto a surface was evaluated using the standard AOAC sporicidal test. The current AOAC test specifies heat shocking after three weeks of incubation. In this study, we evaluated the AOAC sporicidal test by heat shocking immediately following disinfection and after three weeks of incubation as prescribed. Carrier tests showed a greater number of positive B. subtilis carriers when heat shocked immediately following PeraDox™, and PeraDox Ultra™ treatment, than when carriers were heat shocked after three weeks. In summary, results showed that heat shocking increases resuscitation of spores treated with some disinfectants, but not others. Spores in suspension and those dried onto carriers responded similarly to heat shocking. Finally, PeraDox™ formulations had surprisingly rapid sporicidal kinetics.
31
Leonard, Cory A. "Microsporidia Spore Adherence and Host Cell Infection In Vitro." Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etd/1191.
Full textAbstract:
Microsporidia infect invertebrate and vertebrate animals. Human pathogenic microsporidia are associated with severe disease in immunocompromised individuals, and mostly asymptomatic infection in the immunocompetent. Treatment options for microsporidiosis are limited, incompletely effective, and associated with toxicity. Furthermore, microsporidia infection of healthy individuals is poorly understood, and the consequences of asymptomatic infection have not been determined. Little is known about the molecular mechanisms of microsporidia infection, but such information is essential for the development of new therapies. Spores adhere to host cell surfaces in vitro. Our laboratory has focused on determining specific host cell and microsporidia spore surface participants in spore adherence. Our previous studies have shown that host cell sulfated glycosaminoglycans and the spore surface protein EnP1 participate in spore adherence to host cells. Additionally, in vitro inhibition or augmentation of spore adherence decreased or increased host cell infection, respectively. These studies demonstrated the importance of spore adherence in host cell infection and began to characterize the host cell and spore determinants of adherence. The goal of this research was to further characterize host cell and spore participants in microsporidia adherence and infection of host cells in vitro. We characterized an intracellular microsporidia protein and related antibodies for analyses of microsporidia spore surface proteins; characterized a spore surface protein, MsADAM, involved in spore adherence to and infection of host cells in vitro; and suggested a role for host cell integrins in microsporidia adherence to and infection of host cells in vitro.
32
com, Yinglongchen@hotmail, and Yinglong Chen. "Optimization of Scleroderma spore inoculum for Eucalyptus nurseries in China." Murdoch University, 2006. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060809.93928.
Full textAbstract:
Scleroderma, a genus of ectomycorrhizal (ECM) fungi, is often associated with
trees in disturbed habitats and is therefore considered to be suitable for use in
plantation forestry. This study investigated aspects of Scleroderma and its
mycorrhizas with the view to its future use in plantation forestry in south China.
Spores were chosen as inoculum as they are preferred by nursery managers in south
China, due to the lack of on-site fermentation and storage facilities.
To determine the need for inoculation, Eucalyptus plantations in south China
were sampled for sporocarps and mycorrhizas over two years. This study revealed a
low diversity of ECM fungi consisting of 15 taxa fruiting beneath Eucalyptus
plantations. The most common genera were Scleroderma and Pisolithus, but they
were infrequent and the extent of root colonization was poor. Bioassay trials with E.
urophylla as a bait host, using soils collected from 8 eucalypt plantations, confirmed
low levels of inoculum in field soil. It was concluded that introduction of suitable
ECM symbionts into eucalypt nurseries in south China is desirable in the future.
As the Scleroderma genus has not been well studied in Australasia or SE Asia,
over 140 collections gathered mainly from eucalypt plantations in south China and
south-western Australia were described using sporocarp and spore morphology.
Twelve Scleroderma taxa were recognized from collections made from under
eucalypt plantations in south-western Australia and 6 of these were collected from
under eucalypt plantations in south China. In conjunction with classical taxonomy,
30 collections, including those used in inoculation trials, were further characterized
by phylogenetic analyses of ITS or LSU rDNA sequences. These studies supported classical delineation of some Scleroderma species but not all. Although a limited
number of collections were amplified, phylogenetic results showed that most
collections in this study were distinct from the European and Malaysian taxa
extracted from GenBank (89% bootstrap support for both LSU and ITS regions).
In order to optimise spore germination and root colonization, two glasshouse
trials were established to examine suitable spore density and spore storage conditions
on E. globulus and E. urophylla. A spore density of 105 spores seedling-1 was
identified as a suitable dose for promoting root colonization. Spores stored for 5
years at low temperate (4 0C) were almost as effective as freshly collected spores in
forming mycorrhizas.
As the compatibility of Scleroderma fungi with plantation trees is unknown, a
glasshouse experiment examined the ability of 15 collections of Scleroderma to form
mycorrhizas with seedlings of six plantation trees (Acacia mangium, A. mearnsii, E.
globulus, E. urophylla, Pinus elliottii and P. radiata) in a nursery potting mix. Most
collections were able to aggressively colonize eucalypts and pines, while roots of
acacias were poorly colonized. As the Australian collections were more effective in
colonizing short roots on eucalypts than the Chinese collections, it was concluded
Scleroderma should be sourced from outside China for inoculating eucalypts in
Chinese nurseries.
To optimize nursery practices to meet the demand for high quality seedlings and
clonal lines of E. urophylla and hybrids, for outplanting in south China, effects of
rooting medium and inoculation with 6 Scleroderma collections on the growth of E.
urophylla were examined in a nursery in south China. Four types of soil taken from
eucalypt plantations in south China were compared to a potting mix composed of
vermiculite, peat and sand. The inoculant Scleroderma fungi were able to out-compete indigenous mycorrhizal fungi in the rooting media. However, the
potting mix was superior to soils both for plant growth and ECM development under
nursery conditions.
This research should facilitate the use of Scleroderma spores in eucalypt
nurseries in south China. Spore orchards could be set up in China using Australian
Scleroderma spp. from under eucalypts. Spores could be stored dry at 4 0C until they
are required for inoculation in potting mixes in containerized nurseries. However,
before commercial application, further work on persistence of Scleroderma in the
nursery and field, and responses of trees in the field to inoculation, needs to be
undertaken.
33
Metcalf, Talibah U. "The role of SP85 in spore coat formation in Dictyostelium." [Gainesville, Fla.] : University of Florida, 2002. http://purl.fcla.edu/fcla/etd/UFE1001168.
Full text
34
Foss, Kathryn. "S-adenosylmethionine synthetase activity during spore germination in Mucor racemosus." Virtual Press, 1990. http://liblink.bsu.edu/uhtbin/catkey/722465.
Full textAbstract:
When introduced into nutrient medium under air, the asexual sporangiospores of Mucor racemosus germinated within 7 to 8 hours ending in the emergence of germ tubes. Sadenosylmethionine synthetase (SAM synthetase) activity was found to be present in the dormant spore, and increased at a rapid rate after 3 hours. The inhibition of enzyme activity by cycloleucine early in the germination process completely inhibited germ tube formation and only rounded, swollen spores were seen at the end of 7.5 hours. De novo protein synthesis was found to be necessary for SAM synthetase activity throughout the germination process. De novo RNA synthesis was found to be unnecessary for the increase in enzyme activity during the first 3 hours. This suggests that SAM synthetase is coded for in the stored mRNA of the spore. General protein methylation was found to increase through the first 4.5 hours of germination. Autoradiographs of post-translationally methylated proteins subjected to polyacrylamide gel electrophoresis revealed approximately 8 bands which appear to change significantly in the degree of methylation during the 7.5 hour germination process. None of the bands were detectable until the 4.5hour period, which corresponds to the rapid increase in enzyme activity seen after 3 hours.Department of Biology
35
Behravan, Javad. "Characterisation of the gerP spore germination operon of Bacillus cereus." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284763.
Full text
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Clements, Mark Owen. "Molecular and biochemical analysis of B. cereus 569 spore germination." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245590.
Full text
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MacDonald, Oliver Charles. "Splash on leaves and the dispersal of spore carrying droplets." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47549.
Full text
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Manetsberger, Julia. "Investigating the Bacillus megaterium QM B1551 spore coat and exosporium." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709419.
Full text
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Fitzgerald, John Andrew. "Pollen and spore assemblages from the Oligocene Lough Neagh Group." Thesis, University of Sheffield, 1999. http://etheses.whiterose.ac.uk/10365/.
Full textAbstract:
This study was initiated to solve a stratigraphic problem for the Geological Survey of Northern Ireland prior to the revision in 1997 of the 1:250000 map of the solid geology of Northern Ireland. An exploratory drilling programme carried out by the Survey in 1983/1984 revealed the existence of previously unknown Tertiary sediments north west of the Tow Valley Fault. The boreholes revealed a sequence of clays and lignites that were attributed to the Lough Neagh Group. These lay above an interbedded sequence of litho marge, pyroclastics and lacustrine deposits termed the Dunaghy Formation. The Geological Survey required an age to be assigned to this formation and it was proposed that the use of the preserved pollen and spore assemblages offered the best means for dating the sequence. In order to achieve this four boreholes were analysed. Boreholes 13/611, 13/603, 36/4680 and 27/415 contain the Lough Neagh Group. In addition 13/611 and 13/603 contain the Dunaghy Formation. From the pollen and spore assemblages recovered an Oligocene age IS confirmed for the Lough Neagh Group and proposed for the Dunaghy Formation. This information led to the attribution of an Oligocene age to the Dunaghy Formation in the 1997 revised 1:250000 Geological Map of Northern Ireland. The palaeovegetation deduced from the recovered pollen and spore assemblages is in accordance with an Oligocene cooling. The climax angiosperm vegetation, predominantly consisting of temperate forms with some megatherm taxa, grew in a raised bog forest ecosystem within a fluvial-lacustrine environment. All pollen and spore taxa recovered are described including new forms identified. A correlation of the four sections is proposed.
40
Read, S. J. "Spore attachment in fungi with special reference to freshwater hyphomycetes." Thesis, University of Portsmouth, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237285.
Full textAbstract:
Conidia of species of aquatic Hyphomycetes were isolated. axenically cultured and then induced to sporulate in the laboratory. Ten species with diverse conidium morphologies and germination responses were selected for examination at the light microscope and scanning and transmission electron microscope levels. The selected species were: Anguillospora crassa; Articulospora tetracladia: Clavariopsis aquatica: Dimorphospora foliicola; Heliscus lugdunensis; Lemonniera aquatica; Mycocentrospora filiformis; Tetracladium marchalianum; Tumularia aquatica; Varicospol'ium elodeae. fit is shown that the substratum has little effect on germination but that mucilage secretion and appressorium formation ar~_increased on substrata with high surface energies. Attachment. germination. protoappressorium and appressorium formation were more rapid on natural than artificial substrat~., Studies on the strengths of attachment of newly settled conidia using the Fowler Radial Flow Chamber show that tetraradiate conidia are initially more strongly attached than sigmoid conidia and that ovoid conidia are the least well attached. This is related to the number of contact points with the substratum~ The chemistry. texture and morphology of the mucilages formed by each species of aquatic hyphomycete is different and the mucilage on the conidia is frequently distinct from that on the germination structures. Mucilaginous sheaths i are ubiquitous on hyphae and appressoria. The influence of germination and appressorium formation on the strength of attachment was examined in the Fowler Radial Flow Chamber and it is shown that germ tubes. hyphae and. particularly. appressoria increase the strength of attachment to the substratum. The development of attachment structures also serve to reduce the initial differences in adhesion between the individual species.
41
Ali, Nahia A. "Spore germination and the pre-infection phase in ectomycorrhizal fungi." Thesis, University of Surrey, 1986. http://epubs.surrey.ac.uk/843799/.
Full textAbstract:
Spore germination of seven species of ectomycorrhizal fungi was studied under different conditions. Spores of most species tested did not germinate on laboratory media without stimulators. Various stimulators were tested and the greatest activation was that by Pseudomonas stutzeri which was obtained from fruitbodies of Hebeloma crustuliniforme and stimulated about 21% of spores of that fungus. Effects of plant roots on spore germination were studied in the laboratory and in soil. In mineral salts medium, spores of Paxillus involutus were stimulated by five of seven tree species and one of four non-tree species tested. Spores of Laccaria laccata and H. crustuliniforme were stimulated by birch and pine only, while those of lactarius turpis and Amanita fulva were only slightly stimulated by birch roots. Birch was more stimulatory and the highest germination (30%) was that of H. crustuliniforme at 0-1 mm from the root edge. In soil, spores of P. involutus only, of the seven species tested, were stimulated to germinate near roots of birch and spruce in steamed and untreated soils. Birch stimulated up to 96% of spores to germinate in untreated birch wood soil. Spruce had much less effect on germination in either steamed or untreated soil. The majority of germ tubes grew towards the roots. Exudate from roots of seedlings of birch previously grown in soil was active in stimulating germination of H. crustuliniforme, but not of the other six species tested. Activity of the root exudate was associated with the ninhydrin-positive fraction. The role of the basidiospores of the test fungi in initiating mycorrhizas in soil was also studied. Spores of P. involutus and L. laccata established mycorrhizas with birch, but not spruce or pine roots. Spores of the other five species tested did not establish mycorrhizas with any of the plant tested.
42
Adams, Chloe M. "Towards a Structural Understanding of Spore Germination in Clostridium Difficile." ScholarWorks @ UVM, 2015. http://scholarworks.uvm.edu/graddis/287.
Full textAbstract:
Clostridium difficile is a Gram-positive bacterium that causes a toxin-mediated disease, typically in individuals whose normal intestinal flora has been compromised by antibiotic therapy. C. difficile is naturally resistant to many antibiotics and produces spores that can withstand harsh environmental conditions and many disinfectants, making the infection difficult to clear and easy to spread. The infection begins when spores from the environment are ingested and germinate upon exposure to taurocholate and glycine in the digestive tract. This germination process is required to initiate infection and thus represents a good target for the development of novel therapeutics. Although spore germination is necessary for disease transmission, the molecular mechanisms regulating this process are poorly understood. Germination relies on sensing a germinant and triggering degradation of the cortex layer of the spore, which is important for spore resistance. Once the cortex is degraded, the spore can undergo outgrowth to a vegetative cell and secrete toxins to cause disease symptoms.
There are several discrete steps to the proteolytic cascade that ultimately lead to cortex hydrolysis. First, the pseudoprotease CspC acts as a germinant receptor for the bile salt taurocholate; CspC then relays this signal to the subtilisin-like serine protease, CspB. CspB is required for efficient cleavage and activation of the cortex hydrolase. SleC. Upon proteolytic activation of SleC, cortex hydrolysis can proceed, which allows subsequent outgrowth.
To better understand the mechanistic basis of the germination process, we solved the 1.6 Å structure of the required germination protease, CspB, from C. perfringens (a related pathogen). This structure revealed that CspB is comprised of three domains: an associated prodomain, a subtilase domain, and a jellyroll domain. Our work significantly advanced our understanding of the proteolytic cascade that leads to germination; in particular the structure and function of the CspB protease, and the role of its three domains. We have described the four domains of the cortex hydrolase, SleC, and how they contribute to the activity of SleC. We have recently obtained diffraction-quality crystals of the pseudoprotease, CspC, from an organism more closely related to C. difficile, C. bifermentans. Our latest work, focusing on the germination receptor, CspC, has brought us closer to a three-dimensional structure of this protein, which will likely reveal how it binds ligands and functions in germination.
43
Xenopoulos, Panagiotis. "TWIN SPORE FORMATION WITHIN ONE MOTHER CELL BY BACILLUS SUBTILIS." Diss., Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/135810.
Full textAbstract:
Microbiology and ImmunologyPh.D.
Formation of spores by Bacillus subtilis is a primitive system of differentiation that has become a paradigm for studying cell differentiation in prokaryotes. Differential gene expression commences soon after the single, asymmetric sporulation division through the activation of different RNA polymerase sigma factors, sigma F in the smaller prespore and sigma E in the larger mother cell. sigma E activation relies on an inter-cellular signaling emanating from sigma F-directed gene expression. Formation of the asymmetric division septum and compartmentalized activity of both sigma factors occur prior to chromosome partitioning. At the time of septation, only 30% of the chromosome destined to be in the prespore is actually present in that compartment and the remaining 70% is in the mother cell. Thus, both cell types contain unequal DNA content. This study focused on the effect of this genetic asymmetry on sigma F-directed gene expression, and exploited this effect in order to study aspects of sigma F to sigma E inter-compartmental signaling. Perturbed signaling resulted in the discovery of a novel twin-spore forming morphology, which was further characterized. A DNA translocase is required to translocate the remaining portion of the chromosome from the mother cell to the prespore. The replication terminus region of the chromosome was observed to be the last to enter the prespore and thus, sigma F-directed genes showed delayed and reduced expression when moved to a terminus-proximal location. The studies indicate that this positional regulation of sigma F-directed gene expression is attributed to both delayed entry and inhibition in sigma F activity at late stages of sporulation. Moreover, the next prespore-specific sigma factor, sigma G, could have a role in inhibiting sigma F. The link between sigma F and sigma E activation is the spoIIR locus, which is transcribed in the prespore from a sigma F-directed promoter soon after the formation of the asymmetric septum. Inactivation of the structural genes for sigma F or sigma E or SpoIIR results in the formation of a second septum at the opposite pole; development proceeds no further, resulting in an "abortively disporic" phenotype. The second septum is formed about 20 min after the first, and sigma E activity is required to prevent its formation. As a sigma F-directed gene, spoIIR is subject to `positional regulation': a delay in spoIIR expression caused by moving it from its origin proximal position to the chromosome terminus, is sufficient to delay sigma E activation and block spore formation, giving the abortively disporic phenotype. The effects of delaying and enhancing spoIIR expression were tested. The changes delayed sigma E activation, and many organisms formed a septum at both ends. However, both prespores in these organisms were able to develop into mature spores (twins). Extra rounds of chromosome replication occured during twin formation, so that each twin had a chromosome and the mother cell had either one or two chromosomes. This over-initiation of chromosome replication is a prerequisite for twin spore formation. Moreover, the studies showed that mother cells of twin forming organisms were longer than those containing single spores; image analysis showed that mother cell length correlates with chromosome content. In contrast to twin spore formation, during normal spore development, there is usually one copy of the chromosome in the prespore and one in the mother cell, with no growth of either compartment. Therefore, the system allowed investigating regulation of chromosome replication and growth of the mother cell. The studies showed that replication and growth are permitted because of the absence of active sigma E and of reduced levels of transcription directed by the master regulator for entrance to spore formation, Spo0A. The results indicate that the burst of Spo0A-directed expression along with activation of sigma E provide mechanisms to block replication and growth of the mother cell.
Temple University--Theses
44
Chen, Yinglong. "Optimization of Scleroderma spore inoculum for Eucalyptus nurseries in China." Thesis, Chen, Yinglong (2006) Optimization of Scleroderma spore inoculum for Eucalyptus nurseries in China. PhD thesis, Murdoch University, 2006. https://researchrepository.murdoch.edu.au/id/eprint/665/.
Full textAbstract:
Scleroderma, a genus of ectomycorrhizal (ECM) fungi, is often associated with trees in disturbed habitats and is therefore considered to be suitable for use in plantation forestry. This study investigated aspects of Scleroderma and its mycorrhizas with the view to its future use in plantation forestry in south China. Spores were chosen as inoculum as they are preferred by nursery managers in south China, due to the lack of on-site fermentation and storage facilities.
To determine the need for inoculation, Eucalyptus plantations in south China were sampled for sporocarps and mycorrhizas over two years. This study revealed a low diversity of ECM fungi consisting of 15 taxa fruiting beneath Eucalyptus plantations. The most common genera were Scleroderma and Pisolithus, but they were infrequent and the extent of root colonization was poor. Bioassay trials with E. urophylla as a bait host, using soils collected from 8 eucalypt plantations, confirmed low levels of inoculum in field soil. It was concluded that introduction of suitable ECM symbionts into eucalypt nurseries in south China is desirable in the future. As the Scleroderma genus has not been well studied in Australasia or SE Asia, over 140 collections gathered mainly from eucalypt plantations in south China and south-western Australia were described using sporocarp and spore morphology.
Twelve Scleroderma taxa were recognized from collections made from under eucalypt plantations in south-western Australia and 6 of these were collected from under eucalypt plantations in south China. In conjunction with classical taxonomy, 30 collections, including those used in inoculation trials, were further characterized by phylogenetic analyses of ITS or LSU rDNA sequences. These studies supported classical delineation of some Scleroderma species but not all. Although a limited number of collections were amplified, phylogenetic results showed that most collections in this study were distinct from the European and Malaysian taxa extracted from GenBank (89% bootstrap support for both LSU and ITS regions). In order to optimise spore germination and root colonization, two glasshouse trials were established to examine suitable spore density and spore storage conditions on E. globulus and E. urophylla. A spore density of 105 spores seedling-1 was identified as a suitable dose for promoting root colonization. Spores stored for 5 years at low temperate (4 0C) were almost as effective as freshly collected spores in forming mycorrhizas.
As the compatibility of Scleroderma fungi with plantation trees is unknown, a glasshouse experiment examined the ability of 15 collections of Scleroderma to form mycorrhizas with seedlings of six plantation trees (Acacia mangium, A. mearnsii, E. globulus, E. urophylla, Pinus elliottii and P. radiata) in a nursery potting mix. Most collections were able to aggressively colonize eucalypts and pines, while roots of acacias were poorly colonized. As the Australian collections were more effective in colonizing short roots on eucalypts than the Chinese collections, it was concluded Scleroderma should be sourced from outside China for inoculating eucalypts in Chinese nurseries.
To optimize nursery practices to meet the demand for high quality seedlings and clonal lines of E. urophylla and hybrids, for outplanting in south China, effects of rooting medium and inoculation with 6 Scleroderma collections on the growth of E. urophylla were examined in a nursery in south China. Four types of soil taken from eucalypt plantations in south China were compared to a potting mix composed of vermiculite, peat and sand. The inoculant Scleroderma fungi were able to out-compete indigenous mycorrhizal fungi in the rooting media. However, the potting mix was superior to soils both for plant growth and ECM development under nursery conditions.
This research should facilitate the use of Scleroderma spores in eucalypt nurseries in south China. Spore orchards could be set up in China using Australian Scleroderma spp. from under eucalypts. Spores could be stored dry at 4 0C until they are required for inoculation in potting mixes in containerized nurseries. However, before commercial application, further work on persistence of Scleroderma in the nursery and field, and responses of trees in the field to inoculation, needs to be undertaken.
45
Chen, Yinglong. "Optimization of Scleroderma spore inoculum for Eucalyptus nurseries in China." Chen, Yinglong (2006) Optimization of Scleroderma spore inoculum for Eucalyptus nurseries in China. PhD thesis, Murdoch University, 2006. http://researchrepository.murdoch.edu.au/665/.
Full textAbstract:
Scleroderma, a genus of ectomycorrhizal (ECM) fungi, is often associated with trees in disturbed habitats and is therefore considered to be suitable for use in plantation forestry. This study investigated aspects of Scleroderma and its mycorrhizas with the view to its future use in plantation forestry in south China. Spores were chosen as inoculum as they are preferred by nursery managers in south China, due to the lack of on-site fermentation and storage facilities.
To determine the need for inoculation, Eucalyptus plantations in south China were sampled for sporocarps and mycorrhizas over two years. This study revealed a low diversity of ECM fungi consisting of 15 taxa fruiting beneath Eucalyptus plantations. The most common genera were Scleroderma and Pisolithus, but they were infrequent and the extent of root colonization was poor. Bioassay trials with E. urophylla as a bait host, using soils collected from 8 eucalypt plantations, confirmed low levels of inoculum in field soil. It was concluded that introduction of suitable ECM symbionts into eucalypt nurseries in south China is desirable in the future. As the Scleroderma genus has not been well studied in Australasia or SE Asia, over 140 collections gathered mainly from eucalypt plantations in south China and south-western Australia were described using sporocarp and spore morphology.
Twelve Scleroderma taxa were recognized from collections made from under eucalypt plantations in south-western Australia and 6 of these were collected from under eucalypt plantations in south China. In conjunction with classical taxonomy, 30 collections, including those used in inoculation trials, were further characterized by phylogenetic analyses of ITS or LSU rDNA sequences. These studies supported classical delineation of some Scleroderma species but not all. Although a limited number of collections were amplified, phylogenetic results showed that most collections in this study were distinct from the European and Malaysian taxa extracted from GenBank (89% bootstrap support for both LSU and ITS regions). In order to optimise spore germination and root colonization, two glasshouse trials were established to examine suitable spore density and spore storage conditions on E. globulus and E. urophylla. A spore density of 105 spores seedling-1 was identified as a suitable dose for promoting root colonization. Spores stored for 5 years at low temperate (4 0C) were almost as effective as freshly collected spores in forming mycorrhizas.
As the compatibility of Scleroderma fungi with plantation trees is unknown, a glasshouse experiment examined the ability of 15 collections of Scleroderma to form mycorrhizas with seedlings of six plantation trees (Acacia mangium, A. mearnsii, E. globulus, E. urophylla, Pinus elliottii and P. radiata) in a nursery potting mix. Most collections were able to aggressively colonize eucalypts and pines, while roots of acacias were poorly colonized. As the Australian collections were more effective in colonizing short roots on eucalypts than the Chinese collections, it was concluded Scleroderma should be sourced from outside China for inoculating eucalypts in Chinese nurseries.
To optimize nursery practices to meet the demand for high quality seedlings and clonal lines of E. urophylla and hybrids, for outplanting in south China, effects of rooting medium and inoculation with 6 Scleroderma collections on the growth of E. urophylla were examined in a nursery in south China. Four types of soil taken from eucalypt plantations in south China were compared to a potting mix composed of vermiculite, peat and sand. The inoculant Scleroderma fungi were able to out-compete indigenous mycorrhizal fungi in the rooting media. However, the potting mix was superior to soils both for plant growth and ECM development under nursery conditions.
This research should facilitate the use of Scleroderma spores in eucalypt nurseries in south China. Spore orchards could be set up in China using Australian Scleroderma spp. from under eucalypts. Spores could be stored dry at 4 0C until they are required for inoculation in potting mixes in containerized nurseries. However, before commercial application, further work on persistence of Scleroderma in the nursery and field, and responses of trees in the field to inoculation, needs to be undertaken.
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Feliciano, Carolina. "Fight or flight ? : oxygen tolerance mechanisms and spore morphogenesis in the enteropathogen Clostridium difficile." Thesis, Sorbonne Paris Cité, 2019. http://www.theses.fr/2019USPCC086.
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Clostridium difficile qui est une bactérie anaérobie stricte et sporulante, est laprincipale cause des diarrhées associées à la prise d’antibiotiques. Les spores jouent un rôle central dans le cycle infectieux de C. difficile : résistance en dehors de l'hôte, persistance desbactéries et transmission de l’infection. Lorsqu'elles sont ingérées par l'hôte, les spores de C.difficile germent dans le côlon en présence de certains sels biliaires pour former des cellulesvégétatives qui vont produire des toxines responsables des symptômes.Les cellules végétatives sont exposées à différents stress incluant les espèces réactivesde l’oxygène et de l’azote (ROS/RNS) produites par le système immunitaire de l’hôte lors del'inflammation. De plus, bien que le tractus intestinal soit considéré comme anoxique, unefaible teneur en oxygène (O2) est présente dans l’intestin et elle va augmenter après untraitement antibiotique. Pour survivre dans cet environnement oxydant hostile, C. difficile adéveloppé des mécanismes de protection, des voies de détoxification et des systèmes deréparation. Le facteur sigma alternatif de la réponse générale au stress, σB, joue un rôleimportant dans la protection de C. difficile face aux stress rencontrés dans l'hôte incluant l’O2et les ROS. Parmi les gènes contrôlés positivement par σB, nous avons identifié des gènescodant pour des protéines probablement impliquées dans la tolérance à l'O2 et ladétoxification des ROS, comme les deux réverses rubrérythrines (revRbrs), CD1524 etCD1474, et les protéines de type flavodiiron (FDPs), CD1157 et CD1623. Nous avons montréque les gènes codant les deux revRbrs et CD1623 sont exprimés sous le contrôle de σB et demanière hétérogène dans la population bactérienne. Le gène CD1157 est lui exprimé à partirde deux promoteurs dépendants l’un de σA et l’autre de σB. Nous avons ensuite montré queCD1157 a une activité O2-réductase alors que les deux revRbrs ont une activité H2O2- et O2-réductase, l’H2O2 étant le substrat préféré. De plus, nous avons montré qu'un double mutantΔCD1474-ΔCD1524 et un mutant CD1157 sont moins tolérants à une faible tension en O2 etque le mutant ΔCD1623 est plus sensible à l'exposition à l’air. Ces résultats démontrent lerôle clé de ces protéines dans la tolérance à l’O2 et la réponse au stress oxydant chez C.difficile. Au cours du cycle infectieux, dans le côlon, certaines cellules végétatives sporulent.Les couches de surface des spores, le manteau et l'exosporium, permettent aux spores derésister aux stress physiques et chimiques. Cependant, peu de choses sont connues sur leursmécanismes d’assemblage. Dans ce travail, nous avons caractérisé une nouvelle protéine,CotL, qui est nécessaire pour l'assemblage des couches externes de la spore. Nous avonsmontré que le gène cotL est exprimé dans la cellule mère sous le double contrôle des facteurssigma de sporulation, σE et σK. La protéine CotL est localisée dans le manteau de la spore, etles spores du mutant cotL ont un défaut morphologique majeur au niveau des couches dumanteau et de l’exosporium. De plus, les spores du mutant contiennent une quantité réduite deplusieurs protéines du manteau et de l’exosporium et présentent un défaut dans leurlocalisation dans des cellules en cours de sporulation. Enfin, les spores du mutant cotL sontplus sensibles au lysozyme et présentent un défaut de germination, un phénotypevraisemblablement associé à la modification de la structure des couches externes de la spore.Ces résultats suggèrent fortement que CotL est une protéine morphogénétique essentielle àl'assemblage des couches externes de la spore chez C. difficileThe strict anaerobe and sporogenic Clostridium difficile is the most common cause of antibiotic-associated diarrhoea. Spores have a central role in the C. difficile infectious cycle: resistance outside the host, persistence of bacteria during infection and transmission of the disease. When ingested by the host, in the presence of certain bile salts, C. difficile spores germinate in the colon to form vegetative cells that secrete toxins and cause the symptoms of infection. Vegetative cells are exposed to several stresses, among them, reactive oxygen/nitrogen species (ROS/RNS) produced by the host immune system during inflammation. Furthermore, although the intestinal tract is regarded as mainly anoxic, low oxygen (O2) tensions are present in the large intestine and tend to increase after antibiotic treatments. To survive to this hostile oxidative environment, C. difficile had to develop mechanisms of protection, detoxification pathways and repair systems. The alternative sigma factor of the general stress response, ?B, plays an important role in the protection of C. difficile against the different stresses the bacterium is facing inside the host including O2 and ROS. Among the genes positively controlled by ?B, we identified genes encoding proteins likely involved in O2 tolerance and ROS detoxification, such as the two reverse rubrerythrins (revRbrs), CD1524 and CD1474, and the flavodiiron proteins (FDPs), CD1157 and CD1623. We showed that the two revRbrs and the FDP CD1623 are expressed in a ?B-dependent manner and heterogeneously in a cell population. A dual genetic control was demonstrated for the FDP encoding gene CD1157, through ?A- and ?B-dependent promoters. We demonstrated that CD1157 displays O2-reductase activity while the two revRbrs have both H2O2- and O2-reductase activity, being H2O2 the preferred substrate. Moreover, we showed that a double ÆCD1474-ÆCD1524 mutant and a CD1157 mutant are less tolerant to low O2 tension and that the CD1623 mutant is more sensitive to air exposure. These findings demonstrate a key role for these proteins in O2 tolerance and oxidative stress response in C. difficile. During the infection cycle, in the colon some vegetative cells are transformed into spores. The spore surface layers, the coat and exosporium, enable the spores to resist physical and chemical stress. However, little is known about the mechanisms of their assembly. In this work, we characterized a new spore protein, CotL, which is required for the assembly of the spore coat. We showed that the cotL gene is expressed in the mother cell compartment under the dual control of the sporulation sigma factors, ?E and ?K. CotL was localized in the spore coat, and the spores of the cotL mutant had a major morphologic defect at the level of the coat/exosporium layers. Therefore, the mutant spores contained a reduced amount of several coat/exosporium proteins and a defect in their localization in sporulating cells. Finally, cotL mutant spores were more sensitive to lysozyme and were impaired in germination, a phenotype likely associated with the structurally altered coat. Collectively, these results strongly suggest that CotL is a morphogenetic protein essential for the assembly of the spore coat in C. difficile
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André, Stéphane. "Caractérisation et écologie microbienne de lignes de production de conserves." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS047/document.
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Si les flores contaminantes représentent la plupart du temps, dans les conserves, un risque industriel aujourd'hui maitrisé, la flore d'altération, de par sa résistance importante à la température, continue à constituer une cause de pertes économiques majeures. Pourtant cette dernière restait cependant peu caractérisée. En s'appuyant sur les travaux réalisés ces dernières années au sein de l'unité de microbiologie EMaiRIT'S du CTCPA (unité d'Expertise dans la Maitrise du Risque Industriel en Thermorésistants Sporulés du Centre Technique de la Conservation des Produits Agricoles), les principaux objectifs de cette thèse ont été (i) d'identifier et caractériser, en vue de sa maitrise ultérieure, la flore d'altération sporulante (ii) d'identifier l'origine de ces flores dans les conserveries et enfin (iii) de déterminer des moyens de maitrise.Pour cela, un état des lieux des bactéries sporulées d'altération des conserves a été effectué avec la collaboration de 122 conserveries sur plus de 10 ans en France. Cette caractérisation des espèces altérantes a permis l'élaboration d'un outil de biologie moléculaire (SporeTraQTM) afin d'identifier rapidement ces germes ou de pouvoir les détecter au sein d'une population complexe. En parallèle, l'amélioration de la connaissance de la thermorésistance de ces espèces, principale caractéristique de la flore sporulante, a été menée. A ce paramètre, il a été associé une relation avec la chimio résistance des spores. Identifiée, nous avons cherché à localiser cette flore d'altération au sein des usines à l'aide de plusieurs campagnes de prélèvements sur différents légumes. Au final, la flore spécifique du procédé de fabrication des conserves a été identifiée, caractérisée et localisée en vue d'améliorer la maitrise du risque microbien soit par une maitrise des contaminations et/ou un nettoyage plus performant (localisation au niveau d'étapes unitaires, efficacité de molécules sporicides) soir par un barème optimisé (en relation avec la thermorésistance). De plus, ce travail a été conduit au sein d'une approche bénéfice/risque représentant le futur de l'évolution des procédés agro-alimentaires associant amélioration de la qualité nutritionnelle et maintien de la maitrise sanitaire. Cette thèse s'appuie sur 5 publications de rang AMicrobial contaminants of safety concern represent most of time, in canned food, an industrial risk which is well mastered. However, the spoilage flora, due to its high heat resistance, is responsible for major economic losses. Nevertheless, these bacteria remained poorly characterized. Based on the works realized during last 10 years within the EMaiRIT'S unit of microbiology of the CTCPA (expertise unit of the French Technical Center of the Preservation of Food, focused on Management of Industrial Risk liked to Heat Resistant Spores), the main objective of this thesis were: i) to identify and to characterize, with the aim of its later control, the spoilage spore forming bacteria florae ii) to identify the origin of these florae in canning factories and finally iii) to determine ways of control.For that purpose, a current inventory of spore forming bacteria in spoiled canned food was made with the cooperation of 122 canning factories over more than 10 years in France. This characterization of the spoilage species allowed the elaboration of a molecular biology tool (SporeTraQTM) for quick identification of these germs or their detection within a complex population. In parallel, the improvement of the knowledge about the heat resistance of these species, main characteristic of the spores, was led. In addition, the chemical resistance of spores was investigated. When identified, we tried to localize these spores on canning factories lines, with several sampling plans, on various vegetables. At the end, the specific spore forming bacteria related to the industrial canning process was identified, characterized and localized, allowing to improve the microbial risk control either by a more efficient cleaning, and through optimized process schedules. Furthermore, this work was driven within a benefic / risk approach representing the future of the food-processing evolution with improvement of the nutritional quality and the preservation of the sanitary control.This thesis leans on 5 publications of rank A
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Box, Gunnar. "Herstellung rekombinanter Clostridien-Sporen zur Therapie nekrotisierender Tumore." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-56443.
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Svedberg, Jesper. "Catching the Spore killers : Genomic conflict and genome evolution in Neurospora." Doctoral thesis, Uppsala universitet, Systematisk biologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-329498.
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A genome is shaped by many different forces. Recombination can for instance both create and maintain genetic diversity, but the need to locally reduce recombination rates will also leave specific signatures. Genetic elements can act selfishly and spreading at the expense of the rest of the genome can leave marks of their activity, as can mechanisms that suppresses them, in a phenomenon known as genomic conflict. In this thesis, I have studied the forces driving genome evolution, using modern genome sequencing techniques and with a special focus on a class of selfish genetic elements known as Spore killers found in the fungus Neurospora. First, we show novel findings on large-scale suppression of recombination by non-structural means in the N. tetrasperma genomes. In contrary, in the genomic region harbouring the spore killer elements Sk-2 and Sk-3 of N. intermedia, a dense set of inversions that are interspersed with transposable elements have accumulated. The inversions are unique for each killer type, showing that they have a long separated evolutionary history and likely have established themselves independently. For the Sk-2 haplotype, where we have polymorphism data, we see signs of relaxed selection, which is consistent with the hypothesis that recombination suppression reduces the efficacy of selection in this region. These results show the strong effects the divergent selective forces of genomic conflicts can have on chromosome architecture. Furthermore, we investigate the hypothesis that spore killing can drive reproductive isolation, by comparing the fertility of crosses between N. metzenbergii and either killer or non-killer N. intermedia strains. We show that crosses with spore killer strains have lower fertility, which cannot be explained by the killing itself, but is potentially caused by an incompatibility gene captured in the non-recombining region. Finally, we identified the genetic element responsible for causing spore killing in the Sk-1 spore killer strains found in N. sitophila. Unlike the Sk-2 and Sk-3 elements, Sk-1 is not connected to a large, non-recombining region, but is caused by a single locus, and we also find indications that this locus was introgressed from N. hispaniola.
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Manning, Robert John. "Conidiobolus-arthropod interactions : spore germination on arthropod surfaces and its consequences." Thesis, Staffordshire University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272825.
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