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1
com, rohanlowe@gmail, e Rohan George Thomas Lowe. "Sporulation of Stagonospra nodorum". Murdoch University, 2006. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20071101.221432.
Testo completoAbstract (sommario):
Stagonospora nodorum is a necrotrophic fungal pathogen that is the causal agent of leaf and glume blotch on wheat. Very little is currently known about the molecular mechanisms required for pathogenicity of S. nodorum, despite its major impact on Australian agriculture. S. nodorum is a polycyclic pathogen. Rain-splashed pycnidiospores attach to and colonise wheat tissue and subsequently sporulate within 2-3 weeks. Several cycles of infection are needed to build up inoculum for the damaging infection of flag leaves and heads, sporulation is therefore a critical component of the infection cycle of S. nodorum; our aim is to determine the genetic and biochemical requirements for sporulation for development of control of the pathogen. Disease progression of S. nodorum on wheat cv. Amery was monitored by light microscopy to determine the time point when pycnidia development began. Early pycnidia development was evident 12 days post-infection. This information was used to guide a genomics and a metabolomics based approach to determine the requirements for sporulation in S. nodorum. The genomics approach utilised two cDNA libraries created from sporulating and non-sporulating cultures. EST frequency was used to determine highly expressed genes under the two developmental states. Gene expression from the most highly represented genes during sporulation were confirmed using quantitative PCR. A gene encoding an arabitol 4-dehydrogenase (Abd1), was mutagenised, in its absence sporulation was reduced by approximately 20%. The metabolomics approach isolated metabolites from both in planta infection and in vitro growth. Rapid changes in the abundance of metabolites were detected during the onset of sporulation. Key fungal metabolites identified include mannitol and trehalose. The concentration of both mannitol and trehalose increased dramatically in concert with pycnidia formation. Both mannitol and trehalose have also been linked to pathogenicity in filamentous fungi. Creation of deletion mutants of the gene encoding trehalose 6-phosphate synthase showed the synthesis of trehalose is required for full sporulation of S. nodorum in planta and in vitro.
2
Lowe, Rohan George Thomas. "Sporulation of Stagonospora nodorum /". Access via Murdoch University Digital Theses Project, 2006. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20071101.221432.
Testo completo
3
Lowe, Rohan George Thomas. "Sporulation of Stagonospra nodorum". Thesis, Lowe, Rohan George Thomas (2006) Sporulation of Stagonospra nodorum. PhD thesis, Murdoch University, 2006. https://researchrepository.murdoch.edu.au/id/eprint/166/.
Testo completoAbstract (sommario):
Stagonospora nodorum is a necrotrophic fungal pathogen that is the causal agent of leaf and glume blotch on wheat. Very little is currently known about the molecular mechanisms required for pathogenicity of S. nodorum, despite its major impact on Australian agriculture. S. nodorum is a polycyclic pathogen. Rain-splashed pycnidiospores attach to and colonise wheat tissue and subsequently sporulate within 2-3 weeks. Several cycles of infection are needed to build up inoculum for the damaging infection of flag leaves and heads, sporulation is therefore a critical component of the infection cycle of S. nodorum; our aim is to determine the genetic and biochemical requirements for sporulation for development of control of the pathogen. Disease progression of S. nodorum on wheat cv. Amery was monitored by light microscopy to determine the time point when pycnidia development began. Early pycnidia development was evident 12 days post-infection. This information was used to guide a genomics and a metabolomics based approach to determine the requirements for sporulation in S. nodorum. The genomics approach utilised two cDNA libraries created from sporulating and non-sporulating cultures. EST frequency was used to determine highly expressed genes under the two developmental states. Gene expression from the most highly represented genes during sporulation were confirmed using quantitative PCR. A gene encoding an arabitol 4-dehydrogenase (Abd1), was mutagenised, in its absence sporulation was reduced by approximately 20%. The metabolomics approach isolated metabolites from both in planta infection and in vitro growth. Rapid changes in the abundance of metabolites were detected during the onset of sporulation. Key fungal metabolites identified include mannitol and trehalose. The concentration of both mannitol and trehalose increased dramatically in concert with pycnidia formation. Both mannitol and trehalose have also been linked to pathogenicity in filamentous fungi. Creation of deletion mutants of the gene encoding trehalose 6-phosphate synthase showed the synthesis of trehalose is required for full sporulation of S. nodorum in planta and in vitro.
4
Lowe, Rohan George Thomas. "Sporulation of Stagonospra nodorum". Lowe, Rohan George Thomas (2006) Sporulation of Stagonospra nodorum. PhD thesis, Murdoch University, 2006. http://researchrepository.murdoch.edu.au/166/.
Testo completoAbstract (sommario):
Stagonospora nodorum is a necrotrophic fungal pathogen that is the causal agent of leaf and glume blotch on wheat. Very little is currently known about the molecular mechanisms required for pathogenicity of S. nodorum, despite its major impact on Australian agriculture. S. nodorum is a polycyclic pathogen. Rain-splashed pycnidiospores attach to and colonise wheat tissue and subsequently sporulate within 2-3 weeks. Several cycles of infection are needed to build up inoculum for the damaging infection of flag leaves and heads, sporulation is therefore a critical component of the infection cycle of S. nodorum; our aim is to determine the genetic and biochemical requirements for sporulation for development of control of the pathogen. Disease progression of S. nodorum on wheat cv. Amery was monitored by light microscopy to determine the time point when pycnidia development began. Early pycnidia development was evident 12 days post-infection. This information was used to guide a genomics and a metabolomics based approach to determine the requirements for sporulation in S. nodorum. The genomics approach utilised two cDNA libraries created from sporulating and non-sporulating cultures. EST frequency was used to determine highly expressed genes under the two developmental states. Gene expression from the most highly represented genes during sporulation were confirmed using quantitative PCR. A gene encoding an arabitol 4-dehydrogenase (Abd1), was mutagenised, in its absence sporulation was reduced by approximately 20%. The metabolomics approach isolated metabolites from both in planta infection and in vitro growth. Rapid changes in the abundance of metabolites were detected during the onset of sporulation. Key fungal metabolites identified include mannitol and trehalose. The concentration of both mannitol and trehalose increased dramatically in concert with pycnidia formation. Both mannitol and trehalose have also been linked to pathogenicity in filamentous fungi. Creation of deletion mutants of the gene encoding trehalose 6-phosphate synthase showed the synthesis of trehalose is required for full sporulation of S. nodorum in planta and in vitro.
5
Underwood, Sarah. "Sporulation initiation in Clostridium difficile". Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505066.
Testo completoAbstract (sommario):
Clostridium difficile is a leading cause of hospital-acquired diarrhoea, responsible for over 30% of cases of antibiotic-associated colitis, nearly all cases of pseudomembranous colitis and costs the NHS over 200 million per year. This bacterium is able to persist in the hospital environment to cause recurrent infection by the formation of stable spores, refractile to current decontamination procedures. A more comprehensive understanding of the sporulation signal transduction pathway is essential for the design of a decontamination regime effective in removing the spores from the nosocomial environment and the logical design of novel antimicrobial agents. This project aimed to elucidate the mechanism of sporulation initiation . regulation and the role of sporulation-associated proteins in other C. difficile virulence processes, such as toxin production and colonisation. Analysis of sporulation in response to various hospital cleaning agents showed that the combination of a neutral detergent (such as Hospec) with EDTA is a more effective cleaning agent than the chlorine-based agents currently used, as the combination product is uniquely able to both kill vegetative cells and inhibit spore formation. A variety of molecular approaches were used to elucidate information regarding the C. difficile sporulation initiation pathway and the relationship between sporulation and toxin production. Three putative C. difficile sporulation-associated sensor histidine kinases (CD1A, CD2A and CD3B) were identified and shown to be independently involved in sporulation initiation. Furthermore, CD3B has been shown to directly phosphorylate the master response regulator SpoOA, strongly suggesting that this pathway is a two-component system, as opposed to the extended phosphore lay pathway found in B. subtilis. Previous studies on bacteria capable of both toxin production and endospore formation have described links between the two processes. Data presented here indicates SpoOA has a role in indirectly regulating C. difficile toxin A and B production, as the protein is capable of specifically binding promoter regions of the toxin regulatory genes tcdC and tcdD. Inoculation of a triple-stage continuous-culture chemostat that modelled the human gut with C. difficile spoDA- mutant provided further evidence that SpoDA has a key role in both colonisation a!1d toxin production. Overall, this work adds to the growing body of evidence that SpaDA is a master global regulator and has a crucial role in the pathogenicity of C. difficile, making it an excellent target for future novel antimicrobial therapies.
6
Cardaman, Richard C. "Sporulation mutants of Myxococcus xanthus". Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1057779064.
Testo completo
7
Polak, Eline. "Asexual sporulation in the basidiomycete Coprinus cinereus /". [S.l.] : [s.n.], 1999. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13125.
Testo completo
8
Davidson, Philip. "Evolutionary Remodeling of the Sporulation Initiation Pathway". Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1026.
Testo completoAbstract (sommario):
Signal transduction pathways allow organisms to sense and respond appropriately to a complex bouquet of environmental cues. The molecular determinants of specificity are constrained by the demands of signaling fidelity, yet flexible enough to allow pathway remodeling to meet novel environmental challenges. A detailed picture of how these forces shape bacterial two-component signaling systems has emerged over the last decade. However, the tension between constraint and flexibility in more complex architectures has not been well-studied. In this thesis, I combine comparative genomics and in vitro phosphotransfer experiments to investigate pathway remodeling using the Firmicutes sporulation initiation (Spo0) pathway as a model. The present-day Spo0 pathways in Bacilli and Clostridia share common ancestry, but possess different architectures. In Clostridia, a sensor kinase phosphorylates Spo0A, the master regulator of the sporulation, directly. In Bacilli, Spo0 is phosphorylated/activated indirectly via a four-protein phosphorelay. The presence in sister lineages of signaling pathways that activate the same response regulator and control analogous phenotypes, yet possess with different architectures, suggests a common ancestral pathway that evolved through interaction remodeling. The prevailing theory is that the ancestral pathway was a simpler, direct phosphorylation architecture; the more complex phosphorelay emerged within the Bacillar lineage. In contrast to this prevailing view, my analysis of 84 representative genomes supports a novel hypothesis for the evolution of Spo0 architectures, wherein the two protein, direct phosphorylation architecture is a derived state, which arose from an ancestral Spo0 phosphorelay. The combination of my bioinformatic analysis and the first experimental characterization of a Clostridial phosphorelay provide evidence for the presence of functional phosphorelays in both classes Bacilli and Clostridia. Further, a cross-species complementation assay between phosphorelays from each class suggests that interaction specificity has been conserved since the divergence of this phylum, 2.7 BYA. My results reveal a patchy phylogenetic distribution of both Spo0 pathway architectures, consistent with repeated remodeling events, in which a phosphorelay was replaced with a two protein, direct phosphorylation pathway. This remodeling likely occurred via acquisition of a sensor kinase with direct specificity for Spo0A. Further, my analysis suggests that the unusual architectures of the Spo0 pathway and its striking tendency to gain and lose interactions may be due to the juxtaposition of three key properties: the maintenance of interaction specificity through molecular recognition; the ecological role of endosporulation; and the degeneracy of interaction space that permits the ongoing recruitment of kinases to recognize novel environmental signals.
9
Anco, Daniel J. "Epidemiological Studies of the Sporulation Potential and Environmental Factors Affecting Sporulation of Phomopsis viticola on Infected Grapevines". The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1322495236.
Testo completo
10
Arab, Najafi Seyed Mahmoud. "Control of compartment-specific sigma (#sigma'F) in Bacillus subtilis". Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318858.
Testo completo
11
Karandikar, Atul. "Streptomyces coelicolor A3(2) : growth and differentiation of surface grown cultures". Thesis, Liverpool John Moores University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242153.
Testo completo
12
Bone, E. J. "Biochemistry and genetics of sporulation in Bacillus subtilis". Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377250.
Testo completo
13
Merrill, C. "Radiation-induced genetic change during sporulation in Saccharomyces cerevisiae". Thesis, Swansea University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638182.
Testo completo
14
Ryding, Nicholas Jamie. "Analysis of sporulation genes in Streptomyces coelicolor A3(2)". Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296928.
Testo completo
15
Roberts, David Michael. "Chromosome organisation and segregation during sporulation in Bacillus subtilis". Thesis, University of Newcastle upon Tyne, 2018. http://hdl.handle.net/10443/4080.
Testo completoAbstract (sommario):
In times of nutrient scarcity, Bacillus subtilis can form highly resistant spores. Sporulation is a complex differentiation process requiring the coordinated differential expression of hundreds of genes in the smaller prespore and larger mother cell. The critical morphological events in sporulation include a conformational change of the chromosomes and polar anchoring of the chromosome origins that are normally located at quarter cell positions. This is followed by asymmetric cell division that bisects the prespore chromosome, and the subsequent transfer of this chromosome into the spore (Lewis et al., 1994; Wu and Errington, 1998; Ben-Yehuda and Losick, 2002; Ben-Yehuda et al., 2003b; Wu and Errington, 2003). Since these events are critical, there are dedicated systems to ensure their success. This work explores aspects of these processes. In this thesis, I began by attempting to map the precise chromosomal boundaries at the site of the asymmetric septum. For this I performed chromatin-affinity-purification and also developed a methylase-based method. Next, I examined several novel proteins involved in capturing the DNA at the cell pole. This included deciphering the genetic hierarchy and localisation patterns of the newly implicated proteins (MinD and ComN), and confirmed the reported functional redundancy between chromosome capture machineries. Finally my work explored the role played by Soj (ParA) in chromosome movement and origin capture at the cell pole using high resolution microscopy. Soj is a member of the chromosomally encoded B. subtilis ParABS system, and has been long implicated in controlling chromosome segregation and DNA replication initiation (Ireton et al., 1994; Wu and Errington, 2003; Murray and Errington, 2008). My work has demonstrated that the ATPase function of Soj is not necessary for origin capture, but simply the Soj-ATP monomer is proficient. Based on these data, I propose two models for Soj function in polar origin capture during sporulation.
16
Hall, Holly. "The sporulation-specific small regulatory RNAs of Bacillus subtilis". Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/102346/.
Testo completoAbstract (sommario):
Constantly changing environments in nature have led to bacteria evolving regulatory strategies that result in differential gene expression. A novel and understudied aspect of these networks are regulatory RNAs. The Gram-positive model organism Bacillus subtilis not only modulates gene expression to survive a variety of stresses, but also can form endospores to ensure its survival. Sporulation is an essential survival mechanism for many species, allowing them to enter a state of dormancy with resistance to various harsh conditions. This, in turn, ensures survival of not only the population, but also the species. The process of sporulation requires the controlled expression of approximately a quarter of the genes encoded by B. subtilis. Previous large-scale studies have identified that many transcripts do not encode proteins, but exhibited expression profiles similar to genes already known to be part of the sporulation network. Many of these transcripts were selected to likely function as small regulatory RNAs (sRNAs). This study has shown that many putative sRNAs are active during sporulation, three of which show specific phenotypes that alter germination capabilities in the presence of specific germinants. Cells lacking the necessary components to reverse this process are at a strong disadvantage. Detection of favorable growth conditions is key, but how is this conveyed during metabolic inactivity? Initial selection of putative sRNAs was done by in silico characterization. Prediction of transcriptional control and regulatory regions combined with tiling array profiling was used to select putative sRNAs for confirmation in vivo. Transcriptional fusion constructs were generated to confirm compartmental specific expression during sporulation. Spore specific sRNAs were further characterized with phenotypic studies, which suggested a role in endospore formation. This study explored some of the global analysis methods to identify sRNA targets. Whilst no targets for the four chosen sRNAs could be identified, this study produced the most comprehensive data set of proteins to be identified from a B. subtilis endospore.
17
Meador-Parton, Jennifer L. "Structural Analysis of Bacillus subtilis Spore Peptidoglycan During Sporulation". Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/30922.
Testo completoAbstract (sommario):
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
18
Würfl, Stephanie. "Molekularbiologische Untersuchungen zur Regulation der Sporulation in Clostridium acetobutylicum". [S.l. : s.n.], 2008. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-65434.
Testo completo
19
Dembek, Marcin. "Whole-genome analysis of sporulation and germination in Clostridium difficile". Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/38630.
Testo completoAbstract (sommario):
Clostridium difficile is a Gram-positive, obligate anaerobe and a leading cause of hospital-acquired diarrhoea in humans. Under conditions that are not favourable for growth, C. difficile triggers sporulation, producing metabolically dormant endospores through asymmetric cell division. These are regarded as the principal infective stage in the C. difficile life cycle, but must germinate to allow for vegetative cell growth and toxin production, representing an attractive target for intervention. A detailed understanding of sporulation and germination could thus have direct applications for disease prevention. While sporulation and germination in the model sporeformer Bacillus subtilis is well understood, little is known about these events in C. difficile. Therefore, the primary aim of this project was to provide a genome-wide overview of sporulation and germination in C. difficile and to identify genes that are essential in these processes using a combination of molecular microbiology, microscopy, transcriptomics and next-generation sequencing. The first part of this thesis is devoted to the characterisation of C. difficile sporulation and germination dynamics, and is followed by a transcriptional analysis of temporal gene expression in germinating spores. A functional analysis of the 511 genes identified as differentially regulated during germination is provided and the results validated for a number of selected genes. One gene in particular, encoding a membrane associated cell wall protein Cwp7, is examined in more detail. In the second part of this thesis I describe the construction of the first comprehensive transposon mutant library which is then used to identify genes that are essential for sporulation and/or germination using Transposon-Directed Insertion Site Sequncing (TraDIS). The results of this study are validated by constructing in-frame deletions in four selected genes followed by a thorough analysis of the resulting phenotypes. Two genes: CD0125 encoding a homologue of B. subtilis SpoIIQ and CD3567 encoding a putative cell wall hydrolase are shown to be involved in spore formation while CD0106 encoding a homologues of B. subtilis CwlD is shown to be involved in germination.
20
Reodica, Mayfebelle Biotechnology & Biomolecular Sciences Faculty of Science UNSW. "Transcriptional repression mechanisms of sporulation-specific genes in saccharomyces cerevisiae". Awarded by:University of New South Wales. School of Biotechnology and Biomolecular Sciences, 2006. http://handle.unsw.edu.au/1959.4/32731.
Testo completoAbstract (sommario):
For organisms undergoing a developmental process it is ideal that specific genes are induced and repressed at the correct time and to the correct level in a coordinated manner. The process of meiosis and spore formation (collectively known as sporulation) in Saccharomyces cerevisiae provides a convenient system to elucidate transcriptional mechanisms of gene repression and the contribution such repression mechanisms offer to cells capable of undergoing a developmental process. This thesis focuses on transcriptional repression of sporulation-specific genes during both vegetative/mitotic conditions and sporulation. The fitness contribution of transcriptional repressors that regulate sporulationspecific genes during vegetative growth were investigated considering the similarities between meiosis and mitosis such as DNA replication, chromosome segregation and cytokinesis. Well-characterised sporulation genes of different functions were expressed in vegetative cells and ectopic expression of these genes was found not to be lethal. It was ascertained through strain competition studies that ectopic expression of the genes IME1, SMK1, SPR3 and DIT1 during mitotic growth did not affect cellular fitness. The expression of NDT80 in vegetative cells, however, caused a marked reduction in fitness and cells were also further compromised in the absence of the Sum1p repressor that regulates NDT80 transcription. The role of NDT80 as a transcriptional activator of middle sporulation genes, rather than the over-expression of NDT80 as a protein, caused the reduction of cell viability. Transcriptional regulation of the middle sporulation-specific gene SPR3 by the meiosis-specific Set3p repressor complex was investigated using synchronous sporulation cultures of the W303a/?? strain commonly used for sporulation studies. In a mutant W303a/?? ??set3/??set3 strain, lacking a key component of the Set3p repression complex, the transcription of SPR3 was uncharacteristically expressed at higher levels and derepressed during late sporulation. This SPR3 expression was consistent for both SPR3 transcript and SPR3::lacZ reporter protein studies. This preliminary work will enable future studies, using SPR3 promoter deletions fused to a lacZ reporter, aimed at determining the region of the SPR3 promoter that the Set3p complex may interact with to transcriptionally repress the gene during sporulation.
21
Stevens, Christine. "The regulation of gene expression during sporulation in Bacillus subtilis". Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292334.
Testo completo
22
Shu, J. C. "Mutational studies of the regulation of sporulation in Bacillus subtilis". Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288524.
Testo completo
23
Chapman, J. W. "A study of Bacillus subtilis sporulation genes cloned on plasmids". Thesis, Open University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484403.
Testo completo
24
Chatwin, Heather M. "Molecular genetic analysis of chemical-induced sporulation of Myxococcus xanthus". Thesis, University of Warwick, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387398.
Testo completo
25
Ramage, Anne Donaldson. "Genetic analysis of mutations affecting the initiation of yeast sporulation". Thesis, University of Edinburgh, 1990. http://hdl.handle.net/1842/16922.
Testo completoAbstract (sommario):
The spd (sporulation derepressed) mutants of Saccharomyces cerevisiae appear to have lost some of the nitrogen source repression of sporulation but remain subject to glucose repression. In media containing acetate, glycerol or pyruvate as the sole carbon source, these mutants sporulate profusely, a phenotype referred to as hypersporulation (Dawes and Calvert, 1984). This hypersporulation phenotype is also characteristic of mutants in the cAMP signal pathway which have low intracellular levels of cAMP e.g. cdc25, ras2, cdc35, yet the spdl mutants are not allelic to any of these genes. A 4.8 kb DNA sequence on a multicopy plasmid was isolated by its ability to restore growth and inhibit hypersporulation of spdl mutants on YEPG medium. Using the technique of Tn5 transposon mutagenesis, an area of 1.7 - 2.6 kb within the sequence was shown to be responsible for the above effects. The sequence hybridized to chromosome VIII indicating that it was an extragenic suppressor of the SPDI gene, which is situated on chromosome XV. Cells disrupted within the complementing region of the sequence grew more slowly than the corresponding wild-type on YEPD media. On complete media containing ethanol, glycerol or acetate as the sole carbon source, the disruptant did not grow at 30°C but grew at 26°C although at a slower rate than the corresponding wild-type. Diploids ho-mozygous for the above disruption sporulated to a much lesser extent than the corresponding wild-type cells and showed a significantly slower rate of respiration than the wild-type on both YEPD and YEPG media. DNA sequence analysis of the complementing region of the above sequence showed that it was identical to the SCH9 gene which was isolated by Toda et al., (1988).
26
Harry, Kathryn Helene. "Sporulation and enterotoxin regulation by sigma factors in Clostridium perfringens". Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/42517.
Testo completoAbstract (sommario):
Clostridium perfringens is a leading cause of food poisoning annually in the United States. Ingested C. perfringens vegetative cells respond to the acidic conditions of the stomach by initiating sporulation. The process of sporulation is essential in the formation of an enterotoxin (CPE) that is responsible for the symptoms of acute food poisoning. During sporulation, the cell must differentiate into the mother cell and the forespore. Studies in Bacillus subtilis have shown that gene expression during sporulation is compartmentalized, with different genes expressed in the mother cell and the forespore. The cell-specific RNA polymerase sigma factors coordinate the development of the differentiating cell. These sigma factors are Ï F, Ï E, Ï G, and Ï K. The C. perfringens cpe gene, encoding the enterotoxin CPE, is transcribed from three promoters, P1, P2, and P3. P2 and P3 were previously proposed to be Ï E-dependent, and P1 was proposed to be Ï K-dependent based on consensus recognition sequences. In this study, mutations were introduced into the sigE and sigK genes of C. perfringens. In the sigE and sigK mutants, promoter fusion assays indicated that there was no transcription of cpe in either mutant. We also determined through transcriptional analyses that Ï E-associated RNA polymerase and Ï K-associated RNA polymerase co-regulate the transcription of each other. RT-PCR analyses indicated that Ï K is a very early acting sigma factor. The evidence provided here shows that the regulation of sporulation in C. perfringens is not the same as it is in B. subtilis, as previously proposed.Master of Science
27
Palframan, Wendy Jane. "The whiD locus of Streptomyces coelicolorA3(2)". Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267722.
Testo completo
28
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.
Testo completo
29
Wilson, Giles. "A study of the morphological and biochemical differentiation of Saccharopolyspora erythraea". Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/844505/.
Testo completoAbstract (sommario):
The aim of this study was to identify and measure areas of physiology relevant to the initiation of secondary metabolism and spore formation. It was discovered that the growth kinetics of Saccharopolyspora erythraea in a liquid culture environment were dependent on the type of nutrient limitation the organism was exposed to. Sacc. erythraea was able to produce erythromycin and formed structures which had properties similar to those of spores (designated 'sonic resistant units' in this thesis) in a nitrogen limited medium but, would produce erythromycin but no 'sonic resistant units' in a carbon limited medium. This resulted in two liquid culture systems, one which supported the formation of 'sonic resistant units' and one which did not, and thus enabled the comparison of the conditions which resulted in sporulation or secondary metabolism. The measurement of the rate of DNA, RNA and protein synthesis showed distinct profiles of synthesis in both media. Measurements of these rates in Streptomyces hygroscopicus showed similar profiles in the same media suggesting that the behaviour of the macromolecular synthesis rates in different nutrient limiting conditions might be applicable to streptomycetes in general. A change in macromolecular synthesis rate was implicated in inducing secondary metabolism. Antibiotics were used to modulate these rates in an attempt to induce secondary metabolism. Results from these experiments suggested the possible role of the intracellular concentration of charged and uncharged tRNA in induction of antibiotic synthesis. This relationship implies an analogy between the stringent response and the physiology of the induction of secondary metabolism. The formation of spores ('sonic resistant units') did not appear to be induced by changes in macromolecular synthesis rate or changes in tRNA levels or ratio. However, it was evident that the rates of macromolecular synthesis increased during the production of spores and this implied that it is the action of some intracellular agent that is inducing macromolecular synthesis to fuel the spore forming process.
30
Tiley, Anna Mystica Mendez. "Investigating asexual sporulation in Zymoseptoria tritici, a fungal pathogen of wheat". Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715767.
Testo completo
31
Partridge, Sally Rachel. "Regulation of prespore-specific gene expression during sporulation in Bacillus subtilis". Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306742.
Testo completo
32
Illing, Nicola. "The control of differential gene expression during sporulation in Bacillus subtilis". Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276812.
Testo completo
33
Saujet, Laure. "Etude du réseau de régulation de la sporulation chez Clostridium difficile". Paris 7, 2013. http://www.theses.fr/2013PA077269.
Testo completoAbstract (sommario):
Clostridium difficile est un bacille à Gram positif anaérobie strict et sporulé, responsable de diarrhées post-antibiotiques. Peu de données existent sur les processus cellulaires induits à rentrée en phase stationnaire de manière concomitante à la synthèse des toxines et sur les réseaux de régulation contrôlant la phase stationnaire et la sporulation. Nous avons construit un mutant sigH afin de déterminer le rôle de SigH, qui est un facteur sigma alternatif permettant l'expression de gènes de phase de transition et de l'initiation de la sporulation chez B. Subtilis. Nous avons comparé les profils d'expression de la souche 630Aerm et du mutant sigH en début de phase stationnaire. Chez C. Difficile, SigH régule l'expression de nombreux gènes impliqués dans la motilité, la sporulation, la division cellulaire, la virulence et le métabolisme. Enfin, l'expression des gènes de toxines est régulée négativement par SigH. Nous nous sommes ensuite intéressés à la cascade de régulation de la sporulation chez C. Difficile, qui implique 4 facteurs sigma chez B. Subtilis : SigF, SigE, SigG et SigK. Nous avons comparé les profils d'expression ; des mutants sigF, sigE, sigG et sigK et de la souche 630Aerm. Nous avons ainsi défini les régulons de chacun de ces facteurs sigma et montré que chez C. Difficile, le régulon SigE n'est pas sous la dépendance stricte de SigF et que SigG n'est pas nécessaire à l'activité de SigK. Nous avons aussi analysé le réseau de régulation dans chaque compartimeht de la spore et étudié le rôle des régulateurs SpoIIID et SpoVT. Ce travail a mis en évidence une communication moins stricte entre les deux compartiments de la spore que chez B. SubtilisClostridium difficile is a Gram-positive anaerobic spore-forming bacteria which is responsible for post-antibiotic diarrhea. Few data exist on cellular processes induced at the onset of stationary phase concomitantly with the synthesis of toxins and regulatory networks controlling stationary phase and sporulation. We constructed a sigH mutant to determine the role of SigH, which is an alternative sigma factor involved in the transcription of phase transition and initiation of sporulation genes in B. Subtilis. We compared the expression profiles of 630Aerm strain and the sigH mutant after 10 h of growth. In C. Difficile, SigH regulates the expression of many genes involved in motility, sporulation, cell division, virulence and metabolism. Finally, the expression of toxin genes is negatively regulated by SigH. We then studied the regulatory cascade of sporulation in C. Difficile, involving four sigma factors in B. Subtilis: SigF, SigE, SigG and SigK. We compared the expression profiles of the sigF, sigE, sigG and sigK mutants and the 6300erm strain. We defined the regulons of these sigma factors and showed that in C. Difficile, the SigE regulon is not under the strict dependence of SigF and SigG is not necessary for the SigK activity. We also analyzed the regulatory network in each compartment of the spore and studied the rote of SpoIIID and SpoVT regulators. This work showed a less strict communication between the two compartments of the spore in C. Difficile compared to B. Subtilis
34
McCue, Lee Ann. "Molecular analysis of a gene required for sporulation of Streptomyces griseus /". The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487853913101721.
Testo completo
35
Fimlaid, Kelly Ann. "Identification Of Regulatory Factors That Control Clostridium Difficile Sporulation and Germination". ScholarWorks @ UVM, 2016. http://scholarworks.uvm.edu/graddis/458.
Testo completoAbstract (sommario):
Clostridium difficile is a Gram-positive spore-forming strict anaerobe that can cause severe colitis in humans. C. difficile is best known as the leading cause of nosocomial-acquired diarrhea, particularly in people undergoing antibiotic therapies, since it is naturally resistant to most antibiotics. A clinical feature that makes C. difficile infection, or CDI, particularly difficult to treat is the organism's inherent ability to resist antibiotic therapies while in its spore form. Since oxygen is toxic to C. difficile, spores are the major transmissive form; they are also resilient to most disinfectants, which makes them extremely difficult to eliminate to prevent additional infections.
While over fifty years of studies on the spore-forming model organism Bacillus subtilis laid the foundation of how sporulation and germination occurs, little was known about how C. difficile regulates spore formation and/or what proteins are necessary for sporulation and germination processes. The work presented in this dissertation addresses how C. difficile regulates sporulation, identifies genes that are regulated during sporulation, and characterizes some key proteins that are required for either sporulation or germination.
During the developmental process of sporulation, a cell divides into two asymmetrical compartments. In each compartment, specific transcriptional programs controlled by sporulation-specific sigma factors, drive the cell through a series of morphological events, culminating in the formation of a spore. Using genetic and cell biological techniques, we show that mutations in the genes encoding the master transcriptional regulator Spo0A and the sporulation-specific sigma factors σF, σE, σG, and σK block sporulation at various stages. Analysis of the mutants and wild type C. difficile strain using RNA-Sequencing identified genes regulated by a given sigma factor and revealed that the sigma factors control sporulation in a manner that differs from B. subtilis. Whereas the sporulation-specific sigma factor activity is regulated in a sequential manner involving cross talk between the different compartments in B. subtilis, C. difficile regulates these factors in a bifurcated manner, with less cross-compartment regulation.
Guided by our RNA-Sequencing results, we constructed targeted gene mutations in spoIIQ and spoIIIA-H, which are important for forming a channel known as the 'feeding tube' in B. subtilis. We demonstrated that these proteins are necessary for maintaining forespore integrity, tethering the coat to the forespore, and engulfment. Using metabolic labeling, we show that while spoIIQ and spoIIIA mutants cannot finish the phagocytic-like process of engulfment, they are capable of transforming peptidoglycan, which is a necessary step for engulfment to occur.
We also constructed a targeted gene mutation in a gene that is highly transcribed during sporulation, now known as gerS. We show that a gerS mutant cannot degrade cortex during germination and is required for SleC-mediated cortex hydrolysis, making GerS a novel regulator of C. difficile spore germination.
Altogether, this research provides a framework for understanding how the pathogen C. difficile undergoes sporulation and is therefore capable of infecting humans. Further, our studies reveal important factors that mediate the essential process of engulfment during sporulation and an important factor that mediates cortex hydrolysis during germination. This work has demonstrated that C. difficile regulates sporulation and germination differently than what has previously been described in other Firmicutes.
36
Di, Donato Francis Anthony. "Determinants of compartmentalization of gene expression during sporulation in Bacillus subtilis". Diss., Temple University Libraries, 2008. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/4102.
Testo completoAbstract (sommario):
Microbiology and ImmunologyPh.D.;
Bacillus subtilis, a benign gram-positive bacterium, utilizes the strategy of sporulation, which enables it to survive stresses such as starvation, desiccation, and UV irradiation. The spore provides greatly heightened safety to heat and noxious chemicals and remains dormant until conditions become favorable to growth. Sporulation by Bacillus subtilis is a primitive example of cell differentiation. The study of sporulation by Bacillus subtilis has become a paradigm for the study of differentiation in prokaryotes. Central to this process is the establishment of distinct patterns of gene expression in the cell types involved. Our laboratory has developed a two-part sacB/SacY probe to study the temporal and spatial compartmentalization of gene expression. It utilizes the anti-terminator protein SacY to control the transcription of reporter lacZ, (cloned downstream of the sacB gene,) which is regulated by anti-termination. Expression of sacB and SacY is regulated by a pair of promoters specific for sF (prespore specific) and sE (mother cell specific.) Both SacY and sacB must be in the same compartment of the sporulating cell in order to obtain ß-galactosidase activity. Mutagenesis of Bacillus subtilis was employed to identify determinants of compartmentalization of gene expression during sporulation. Mutants were screened for loss of compartmentalization using the two-part probe. In addition to the two-part sacB/SacY probe, a second method was developed; transposon mutagenesis was performed on strains where expression of gfp was regulated by promoters recognized by either sF or sE. Cells deficient in sporulation were isolated and evaluated by fluorescence microscopy for uncompartmentalized gfp expression. A rescue vector was developed that allowed for efficient cloning of Tn10 insertions. This plamid, pJP17, proved to be an essential tool. Mutations causing uncompartmentalized sF activity were identified in spoIIIE, spoIIIAA, spoIIIAB, spoIIIJ, spoIIE, spoIIAA, spoIID, spoIIM, kinA and ald. The spoIIIE mutation provides the most dramatic phenotype, and was the only mutation, that resulted in 100% loss of compartmentalization during stage II of sporulation. In contrast to all other mutants, the dramatic stage II loss of compartmentalized activity of sF indicates a regulatory role for SpoIIIE, which has yet to be elucidated. Taken together, these results indicate a central role for SpoIIIE in preventing activation of sF in the mother cell in addition to its DNA translocation activity.
Temple University--Theses
37
Rostami, Nadia. "Co-ordination of DNA replication initiation and chromosome segregation during sporulation". Thesis, University of Newcastle upon Tyne, 2015. http://hdl.handle.net/10443/2884.
Testo completoAbstract (sommario):
The essence of viability and fitness of an organism is dictated by proper transmission of the genetic material from the parent to the progeny. Therefore in all organisms, processes of DNA replication and chromosome segregation are highly coordinated to match growth and cell division. Spore development in the model organism Bacillus subtilis provides a tractable system for studying a number of cellular processes including DNA replication and chromosome segregation. In the early stages of sporulation, DNA replication initiation is tightly regulated so that a single cell replicates only once and the diploidy is maintained. This is achieved through regulation of the interaction between the initiator protein DnaA and specific DNA elements arrayed at the origin of replication. DnaA assembles at the origin and promotes DNA unwinding and the assembly of a replication initiation complex. SirA is a DnaA-interacting protein that interacts with the N-terminal domain of DnaA and inhibits initiation of DNA replication in diploid Bacillus subtilis cells committed to sporulation. However the underlying mechanism by which SirA regulates the chromosome copy number in sporulating cells remains elusive. In the study presented here, I report that the in vivo examination of GFP-SirA localisation indicates that the protein accumulates at the replisome in sporulating cells. Also taking advantage of the newly released SirA crystal structure in complex with the N-terminal domain of DnaA (domain I), I show that the SirA localisation is dependent on the integrity of the interface identified in the co-crystal structure. This suggests that SirA accumulation at the replisome is likely a through a direct interaction with DnaA. In order to test the significance of inhibition of reinitiation events during spore development, I examined the chromosomal origin segregation in sporulating cells defective in regulating DnaA. I found that cells that lack regulators of DnaA; SirA, Soj or YabA exhibit 3 reduced fidelity in chromosomal origin trapping in the forespore compartment. I also provide evidence that the origin trapping defect observed in the cells lacking DnaA-regulators; SirA and YabA is a direct result of loss of regulation of DnaA. Finally, I show that Soj plays a DnaA-independent role in chromosomal origin trapping, for which its ability to localise at the septum seems to be required.
38
Maughan, Heather. "Evolution of Sporulation in Bacillus Subtilis: Functional Loss and Evolutionary Consequences". Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/193989.
Testo completoAbstract (sommario):
The loss of phenotypes, a phenomenon capable of leading to ecological specialization, has been observed to occur readily during evolution and is an important contributor to the phenotypic variation observed in nature. While the loss of phenotypes is often observed, the population genetic processes responsible for phenotypic loss are not well understood. This lack of understanding is due to the complexity of evolutionary process and the intricacy of how information from the genotype develops into the phenotype. The work presented in this dissertation is a first attempt to disentangle the complexity of the population genetics of trait loss in experimental populations of Bacillus subtilis, a bacterium of the low G+C Gram positive group. The experiments described in this dissertation showed that the deletion of two complex phenotypes occurred throughout evolutionary time. While there is evidence suggesting that this phenotypic loss may be due to trade-offs between traits that were lost and those important for fitness, i.e. selection, the contribution of neutral mutation accumulation cannot be ruled out. Genomic studies identified candidate expression changes potentially able to explain the observed phenotypic loss, paving the way for future work linking the observed phenotypic changes with their underlying genetic and developmental cause(s). The results from this dissertation work speak to the complexity of trait loss and the difficulty of explicitly determining whether selective or neutral processes are responsible for trait loss in nature.
39
García, García Tránsito. "Functional analysis of phosphorylation of the replication controller YabA in Bacillus subtilis". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS506/document.
Testo completoAbstract (sommario):
Les bactéries ont besoin d’adapter leur cycle cellulaire et leur taux de croissance aux changements environnementaux et nutritionnels. L’initiation de la réplication est ainsi strictement coordonnée aux autres processus cellulaire afin de transmettre un chromosome conforme. Chez B. subtilis, bactérie modèle des Gram⁺, la protéine YabA joue un rôle majeur en réprimant l’initiation de la réplication, ceci en formant un complexe avec la protéine initiatrice DnaA et la clamp polymérase DnaN. YabA interagit en outre avec d’autres protéines partenaires et serait donc multifonctionnelle. Sa structure 3D révèle une architecture en deux domaines: Un domaine N-terminal adoptant un repliement de type superhélice et un domaine C-terminal globulaire structuré autour d’un atome de Zinc. In vivo, YabA est un tétramère par interaction entre les superhélices, connecté aux domaines C-terminaux monomériques par une séquence déstructurée hyper flexible. YabA serait un hub structural interagissant simultanément avec plusieurs protéines et constituerait une plate-forme d’intégration entre différents signaux intracellulaires et l’initiation de la réplication. La phosphorylation est une modification post-traductionnelle modulant l’activité de nombreuses protéines en réponse à certains signaux cellulaires. Grâce à des expériences de phosphorylation in vitro et des analyses de spectrométrie de masse, nous avons montré que YabA est phosphorylée par la kinase de type Hanks YabT sur une thréonine, localisée dans la région flexible de liaison interdomaines. YabT est une kinase activée par l’ADN, exprimée en carence en glucose, en sporulation et en phase stationnaire. Nous avons construit des mutants phosphomimétique de YabA (yabA-T71D) et non phosphorylable (yabA-T71A) pour i) confirmer le rôle de T71 dans la phosphorylation et ii) réaliser des études fonctionnelles.Nous avons montré in vivo que la phosphorylation de YabA n’est pas impliquée dans l’initiation de la réplication, mais module des programmes de différenciation. La phosphorylation de YabA module inversement la sporulation et la formation de biofilm, ce qui souligne sa multifonctionnalité et son implication dans la signalisation cellulaire connectant l’initiation de la réplication et la différenciation. Nos résultats suggèrent que la phosphorylation YabT-dépendante de YabA affecte la différenciation en modulant le taux intracellulaire de Spo0A-P. En effet, la phosphorylation de YabA est corrélée à un taux élevé de Spo0A-P, ce qui stimule la sporulation et inhibe la formation de biofilm. Par ailleurs, nos expériences de chromatographie sur couche fine (TLC) et de “In-Gel” suggèrent que YabA possède une activité “ATP/GTPasique” atypique modulée par la phosphorylation de YabA sur T71. Nos analyses fonctionnelles révèlent un rôle potentiel de YabA sur des voies de signalisation dépendant du c-di-GMP, qui contrôle la formation du biofilm chez de nombreuses bactéries. Ces résultats suggèrent que YabA joue un rôle complexe pendant la différenciation en intégrant différentes voies de signalisation. Enfin, des analyses de LC-MS montrent que lorsqu’elle est surexprimée chez Escherichia coli, YabA est phosphorylée sur la tyrosine 90, qui appartient au domaine d’interaction C-terminal. Une étude double-hybride chez la levure montre que la phosphorylation de Y90 module l’interaction de YabA avec ses partenaires DnaA et DnaN. In vivo, la phosphorylation de Y90 module l’initiation de la réplication. La kinase impliquée n’a pas encore été identifiée, mais ces résultats suggèrent l’existence d’un contrôle de l’initiation de la réplication lié à la phosphorylation de YabA chez B. subtilis. En conclusion, l’ensemble de nos études suggèrent l’existence de différents niveaux de régulation de l’activité de YabA par phosphorylation sur thréonine et tyrosine. YabA, outre son rôle dans l’initiation de la réplication, joue un rôle majeur dans la différenciation de B. subtilisUpon environmental or nutritional changes, bacteria must adjust their cell cycle with their growth rate. Most particularly, DNA replication initiation events must be controlled and coordinated with cell physiology to ensure faithful chromosome inheritance. In Bacillus subtilis, a model of Gram-positive bacteria, YabA plays a major role in down regulating initiation replication through interaction with the initiator protein DnaA and the clamp polymerase DnaN. However, YabA is a structural hub protein able to interact with other protein partners, indicating it might be multifunctional. Through its unique overall tri-dimentional structure composed of N-terminal four helix-bundle tetramer connected to four monomeric C-terminal domains by a highly flexible linker, YabA is capable to physically interact with more than one protein at a time, thus providing a suitable platform to integrate intracellular signals to replication initiation. Phosphorylation is the most prevalent post translational modification that modulates protein activities in response to cellular signals. Using in vitro phosphorylation and mass spectrometry we demonstrated that YabA is phosphorylated by the Hanks-type serine/threonine kinase YabT at a threonine residue localized within the flexible inter-domain region. YabT is a kinase activated by DNA and up-regulated during glucose starvation, sporulation and stationary phase. We constructed YabA phosphomimetic (yab-AT71D) and non-phosohorylatable (yabA-T71A) mutants to (i) confirm the requirement of T71 for YabT-mediated phosphorylation in vitro and (ii) perform in vivo and in vitro functional studies.We show in vivo that the phosphorylation of YabA is not involved in initiation control, but rather modulates bacillus developmental processes. We found that YabA phosphorylation inversely regulates sporulation and biofilm formation highlighting the multifunctional role of YabA as well as its role in integrating physiological signals to connect chromosomal replication initiation control with cell development. Our results support a role of YabT-mediated phosphorylation of YabA in Bacillus subtilis life-style decision making through the modulation of Spo0A-P intracellular levels. We established that YabA phosphorylation correlates with high cellular levels of Spo0A-P, leading to sporulation stimulation and preventing biofilm formation. Additionally, thin layer chromatography (TLC) analysis and In-Gel assays showed that YabA possess an atypical "ATP / GTPase" activity. This unusual activity seems to be modulated by phosphorylation of the YabA T71 residue. Our functional analysis pointed to a potential role of YabA in the c-di-GMP signaling transduction pathway, known to regulate biofilm formation in many bacteria. This suggesting a complex regulatory role of YabA during development, involving signaling crosstalk. LC-MS analyzes showed that when overexpressed in Escherichia coli, YabA is phosphorylated on the residue Y90 in a YabT independent manner. Y90 belongs to the interaction C-terminal domain, which contacts DnaA and DnaN. We found that Y90 was involved YabA-mediated replication initiation control. We provided evidence that phosphorylation state of YabA at Y90 can potentially modulates a protein-interaction switch with its protein partners DnaA and DnaN in a yeast-two-hybrid-based assay. Although we did not identified a kinase responsible for the phosphorylation of YabA at Y90 in B. subtilis, this finding hint at the possibility of a YabA-mediated control of initiation modulated by phosphorylation in this bacteria. Thus, all of these in vitro and in vivo observations suggest the existence of different modes of regulation of YabA activity by phosphorylation, involving threonine and tyrosine residues. This study established that YabA, apart from its role during replication initiation, plays a key regulatory role in B. subtilis development
40
Pozzi, Adrien C. "Rôles adaptatifs et contraintes de la sporulation chez les microorganismes associés aux plantes : cas de la sporulation in planta dans la symbiose actinorhizienne Frankia (Frankiaceae)–Alnus (Betulaceae)". Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10359/document.
Testo completoAbstract (sommario):
Frankia est une actinobactérie capable d'établir une symbiose racinaire avec les plantes actinorhiziennes dont le genre Alnus. Seulement certaines souches de Frankia sont capables de sporuler in planta, ce qui est illustré par la présence (Sp+) ou l'absence (Sp–) de sporanges dans les cellules végétales de la nodosité. C’est à notre connaissance un cas unique de sporulation endophyte. Cependant la description et l’interprétation écologique de ce trait d’histoire de vie (THV) original étaient incomplètes. Notre contribution à l’étude de la sporulation in planta des Frankia infectives de l’aulne intègre des approches théorique, descriptive et expérimentale, pour préciser (i) l’influence relative de la souche bactérienne, de l’espèce de la plante-hôte et des conditions pédoclimatiques sur ce THV, (ii) le rôle de la variabilité environnementale sur la distribution, la diversité et la sélection du trait, ainsi que (iii) les coûts et bénéfices associés pour les deux partenaires. Nous avons démontré pour la première fois que la sporulation in planta est un THV (i) spécifique de certaines lignées de Frankia, (ii) majeur pour en comprendre l'histoire évolutive et (iii) significativement corrélé à des caractéristiques génétiques des souches. Nous avons également confirmé que l’occurrence du trait varie selon l’environnement. Nous avons enfin établi un modèle de l'évolution du trait abordant sa valeur adaptative. L’ensemble des réflexions menées et des résultats obtenus nous permet de discuter de la sporulation in planta dans le cadre d’un continuum de stratégies symbiotiques, et plus généralement de discuter de l’écologie évolutive des symbioses entre microorganismes et plantesFrankia sp. is a telluric actinobacteria able to establish a root symbiosis with actinorhizal plant such as Alnus sp. Only some Frankia strains are able to sporulate in-planta, as spores can be present in (Sp+) or absent from (Sp–) the vegetal cells of the root nodule. It is to our knowledge a unique case of endophytic sporulation. However, the description and the ecological interpretation of this original life-history trait (LHT) were scarce. Our contribution to the study of the in-planta sporulation of Alnus-infective Frankia sp. combines theoretical, descriptive and experimental approaches to precise (i) the relative effect of the bacterial strain, the host-plant species and the pedoclimatic conditions on this LHT, (ii) the effect of the of the environmental variability on the distribution, diversity and selection of the trait, and (iii) the associated costs and benefits for the two symbiotic partners. We demonstrated for the first time that the in-planta sporulation is a LHT (i) specific to some Frankia lineages, (ii) major to understand their evolutionary history and (iii) significantly correlated to particular genetic features. We also shown that the occurrence of the trait varies according to the environment We also proposed a model of the evolution of the trait taking its fitness into account. We bring all the previous considerations and results to discuss the inplanta sporulation trait within a continuum of symbiotic strategies and more generally to discuss the evolutionary ecology of plant-microbe symbioses
41
Gilmore, Meghan Elizabeth. "Analysis of the Roles of the cwlD Operon Products during Sporulation in Bacillus subtilis". Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/35779.
Testo completoAbstract (sommario):
CwlD has sequence similarities to N-acetyl muramoyl-L-alanine amidases, a class of enzymes known to cleave the bond between the peptide side chain and the N-acetyl muramic acid residue in cortex peptidoglycan formation during sporulation. A major difference between vegetative peptidoglycan and spore peptidoglycan is the presence of muramic-d -lactam (MAL) in spore peptidoglycan. It was previously determined that a cwlD null mutant does not contain muramic-d -lactam in the spore cortex peptidoglycan and the mutant spores were unable to complete germination. Therefore, it is believed that CwlD plays a role in MAL formation during sporulation. However, the specific role of the protein had not been demonstrated. It was also previously found that cwlD is in a two-gene operon with orf1. Orf1 is produced within the forespore with CwlD. The hypothesized role of Orf1 is to inhibit CwlD activity from within the forespore.
Muramoyl-L-alanine amidase activity was demonstrated by CwlD in vivo. Therefore, CwlD is carrying out the first step of MAL synthesis, cleaving the peptide side chain while other enzymes are needed to complete MAL formation. Two different forms of CwlD were over-expressed, with and without the protein's signal peptide sequence. Both forms of the protein were purified and in both cases activity was undetectable. Antibodies specific for CwlD were obtained which can be used in future research as a tool to further characterize CwlD activity.
A series of B. subtilis cwlD operon mutants were constructed altering the expression patterns of Orf1 and CwlD within the mother cell and forespore compartments. Various resistance properties and the germination ability of the mutant dormant spores were analyzed. It was determined that the absence of just Orf1 or Orf1 and CwlD from within the forespore has no effect on the phenotypes tested. Peptidoglycan from developing mutant forespores was extracted and analyzed throughout sporulation. Evidence was obtained demonstrating that the role of Orf1 is not to inhibit CwlD from within the forespore as hypothesized.Master of Science
42
Malleck, Tiffany. "Mécanismes d’adaptation de Moorella thermoacetica/thermoautotrophica sur les lignes de production de produits alimentaires appertisés". Thesis, Avignon, 2017. http://www.theses.fr/2017AVIG0339/document.
Testo completoAbstract (sommario):
Moorella thermoacetica est une bactérie d’altération anaérobie thermophile sporulée produisant les spores les plus thermorésistantes isolées à ce jour en industrie agroalimentaire. Les spores de M. thermoacetica peuvent survivre aux traitements d’appertisation appliqués dans l’industrie de la conserve et représente la principale cause d’altération de conserves peu acides après incubation à 55 °C. Les mécanismes mis en place pendant la sporulation, ainsi que l’impact des facteurs environnementaux sur la sporulation et les propriétés des spores de Moorella sont largement méconnus.L’objectif de ces travaux était donc de caractériser l’impact de la température sur les caractéristiques de sporulation et de résistance des spores ainsi que de déterminer les mécanismes moléculaires impliqués dans la sporulation. Nous avons montré que la capacité de sporulation est meilleure lorsque la sporulation est effectuée à la température optimale (55 °C) en comparaison avec les températures limites basse et haute (45 °C et 65 °C, respectivement). De plus, les spores de M. thermoacetica produites à 45 °C sont plus sensibles à la chaleur humide et aux biocides que les spores produites à 55 °C. La structure des spores ainsi que leur composition protéique varient en fonction de la température de sporulation. Une étude RNAseq menée au cours de la sporulation de M. thermoacetica en conditions optimales régulées a montré que la plupart des 167 gènes de sporulation, identifiés in silico dans le génome de M. thermoacetica ATCC39073, est sur-exprimée pendant la sporulation. Ces résultats suggèrent que les mécanismes décrits chez d’autres espèces endosporulées sont conservés chez Moorella.L’ensemble des données acquises montrent que la température joue un rôle essentiel dans les caractéristiques de sporulation et de résistance des spores de M. thermoacetica mais également que les mécanismes moléculaires impliqués dans la sporulation semblent conservés au regard des données disponibles pour d’autres espècesMoorella thermoactica is a spoilage anaerobic and thermophilic spore-former producing the most highly heat-resistant spores isolated so far in food industry, which enables the bacteria to survive the sterilization process applied in cannery. M. thermoacetica is the main cause of low acid canned food spoilage after incubation at 55 °C. Little is known about sporulation mechanisms and spore properties according to environmental conditions.In this work, we aimed at characterizing the impact of environmental conditions on sporulation and spore resistance properties, as well as describing the molecular mechanisms underlying sporulation. We showed that sporulation capacities are higher when sporulation is performed at the optimal temperature (55 °C) that at limit temperatures (45 °C and 65 °C). Besides, spores are less resistant to wet heat and biocides when formed at 45 °C than at 55 °C. We showed that the ultrastructure and spore protein composition varied according to sporulation temperature. Moreover, the study of gene expression by RNAseq during sporulation in optimal regulated conditions showed that most of the 167 genes involved in the sporulation process and identified in silico in M. thermoacetica ATCC 39073 genome, were up-regulated during sporulation, suggeting that the mechanisms described in other endospore-formers are conserved in Moorella.Altogether, our results showed that sporulation temperature strongly impacts sporulation and spore properties of M. thermoacetica and that sporulation mechanisms tend to be conserved in Moorella considering data available on other endospore-formers
43
Sonoda, Yo. "Structural and functional analysis of a sporulation protein Spo0M from Bacillus subtilis". Kyoto University, 2016. http://hdl.handle.net/2433/215587.
Testo completoAbstract (sommario):
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第19761号
農博第2157号
新制||農||1039(附属図書館)
学位論文||H28||N4977(農学部図書室)
32797
京都大学大学院農学研究科応用生命科学専攻
(主査)教授 三上 文三, 教授 加納 健司, 教授 喜多 恵子
学位規則第4条第1項該当
44
Gauvry, Emilie. "Modélisation de la sporulation de Bacillus subtillis BSB1 et liens physiologiques avec les cinétiques de croissance". Thesis, Brest, 2017. http://www.theses.fr/2017BRES0140/document.
Testo completoAbstract (sommario):
Les bactéries sporulées sont à l’origine de risques sanitaires et d’altération des produits alimentaires. Elles peuvent sporuler pour former des cellules résistantes à diverses agressions physiques ou chimiques. Afin de limiter la formation des spores dans les aliments et sur les lignes de production en industrie agroalimentaire, une approche préventive consiste à prévoir ce processus bactérien en fonction des conditions environnementales rencontrées durant les procédés de fabrication. Pour cela, un modèle cinétique décrivant à la fois la croissance et la sporulation de la bactérie modèle Bacillus subtilis BSB1 a été développé. Ce modèle est un outil utile pour évaluer l’impact des facteurs environnementaux sur des aspects quantitatifs et physiologiques de la croissance et de la sporulation. Des conditions défavorables de température, de pH et d’activité de l’eau provoquent un ralentissement de la croissance bactérienne, une sporulation plus synchrone dans la population de B. subtilis conduisant à une apparition plus tardive des spores et une production plus faible de spores. Tous ces effets ont été décrits avec un modèle prévisionnel de croissance et de sporulation : le modèle cardinal. Ces modèles (cinétique et cardinal) sont efficaces pour prévoir la croissance et la sporulation de B. subtilis BSB1 dans différentes conditions de culture, différentes matrices et en conditions dynamiques de facteurs environnementaux. Ces travaux et ces modèles mathématiques permettront de mieux comprendre le comportement de sporulation des bactéries en fonction des facteurs environnementaux et ainsi, de mieux appréhender la sporulation en industrie agroalimentaireSpore-forming bacteria cause health risks and alteration of food products. They can sporulate to form cells resistant to various physical or chemical aggressions. In order to limit the formation of spores in food and on production lines in the agri-food industry, a preventive approach consists in predicting this bacterial process according to the environmental conditions encountered during the manufacturing processes. For this, a kinetic model describing both growth and sporulation of the bacterium model Bacillus subtilis BSB1 was developed. This model is a useful tool for assessing the impact of environmental factors on quantitative and physiological aspects of growth and sporulation of B. subtilis. Unfavorable conditions of temperature, pH and water activity cause a slowing of B. subtilis’ growth, a more synchronous sporulation in the bacterial population leading to later spore emergence and lower spore production. All these effects have been described with a predictive model of growth and sporulation: the cardinal model. These (kinetic and cardinal) models are efficient to predict growth and sporulation of B. subtilis BSB1 in different culture conditions, different matrices and in dynamic conditions of environmental factors. This work and these mathematical models will allow a better understanding of the sporulation behavior of bacteria according to environmental factors and thus a better understanding of the sporulation in the agrofood industry
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Abbas, Amina Aicha. "Effet de l’absence d’oxygène sur la capacité de sporulation et les propriétés des spores de Bacillus cereus". Thesis, Avignon, 2014. http://www.theses.fr/2014AVIG0330/document.
Testo completoAbstract (sommario):
L’effet de la température et de la composition du milieu en nutriments sur les propriétés des spores (résistance et germination) de B. cereus a été largement étudié contrairement à l'effet de l'anaérobiose. Or, les cellules végétatives de B. cereus peuvent se retrouver dans une grande variété de milieux naturels avec un faible niveau d'oxygène (intestin, sol, lignes de traitement des aliments…) où la sporulation peut avoir lieu. Les spores produites dans ces conditions anaérobies pourraient donc avoir des propriétés particulières. Dans ce travail, un panel de 18 souches de B. cereus appartenant aux groupes phylogénétiques de II à VII a été étudié pour sa capacité à sporuler en anaérobiose dans un milieu de sporulation approprié que nous avons développé (MODS). En anaérobiose, la capacité de sporulation a été plus faible et plus hétérogène qu’en aérobiose. La souche AH187 a produit le niveau de spores le plus important en anaérobiose, elle a donc été choisie pour étudier les propriétés de ces spores. Les spores produites en anaérobiose étaient plus résistantes à la chaleur humide entre 90°C et 100°C, à 1M de NaOH, 1M d'acide nitreux et à la lumière pulsée. Aucune différence dans la résistance à 5 % de peroxyde d'hydrogène ou à 0.25 mM de formaldéhyde, ni aux UV-C, n'a été observée entre les deux conditions. En présence de L- alanine, les spores produites en anaérobiose germaient plus efficacement que celles produites en aérobiose tandis qu’aucune différence dans la germination n’a été observée en présence d'inosine. Aucune différence dans la taille des spores produites dans les deux conditions n’a été observée par microscopie électronique à transmission. Toutefois, les spores obtenues dans des conditions anaérobies avaient un exosporium endommagé ou dans certains cas un exosporium complètement détaché, contrairement aux spores produites dans des conditions aérobies. Afin de comprendre les différences dans la capacité de sporulation de B.cereus entre les 2 conditions, des PCR en temps réel (RT-PCR) ont été utilisées pour étudier l'expression des gènes de l'initiation de la sporulation spo0A, spo0B, spo0F, KinA et kinB. Les cinétiques d'expressions des gènes spo0A, spo0B, spo0F et KinA avaient la même tendance. Ils étaient caractérisés par une expression plus élevée en anaérobiose par rapport à l’aérobiose au début et à la fin de la phase exponentielle de croissance. En outre, l'expression du gène kinB était caractérisée par une augmentation en anaérobiose par rapport à l’aérobiose pour atteindre un pic entre 4 h (milieu de phase exponentielle) et 6 h (début de phase stationnaire) de croissance. Les gènes spo0A, spo0B, spo0F, KinA et kinB sont exprimés de manière différentielle entre l’aérobiose et l’anaérobiose. Ces données pourraient aider à comprendre la différence de capacité de sporulation de B. cereus entre la condition aérobie et anaérobieThe effect of temperature and nutrient composition of the medium on B. cereus spore properties (resistance and germination) has been extensively studied unlike to the effect of anaerobiosis. Nevertheless, B. cereus vegetative cells can be found in a large variety of natural environments with low oxygen level (intestine, soil, food processing line) where sporulation take place. Spores produced in these anaerobic environments could have particular properties. In this work, a panel of B. cereus strains belonging to phylogenetic groups II to VII was studied for their capacity to sporulate in anaerobiosis in an appropriate sporulation medium we developed (MODS). In anaerobiosis, sporulation ability was lower and more heterogeneous than in aerobiosis. The B. cereus AH187 strain produced the highest level of spores in anaerobiosis, it was therefore chosen to study spore properties. Spores produced in anaerobiosis were more resistant to wet heat from 90°C to 100 °C, 1M NaOH, 1M nitrous acid and pulsed light. No difference in resistance to 5 % hydrogen peroxide or 0.25 mM formaldehyde or UV-C was observed between these two conditions. In the presence of L-alanine, spores produced in anaerobiosis germinated more efficiently than spore produced in aerobiosis. No difference in germination was observed with inosine. No difference in the spores size produced in the two conditions was observed by transmission electron microscopy. However, spores obtained under anaerobic conditions had a damaged exosporium, or in some cases a completely detached exosporium, unlike spores produced under aerobic conditions. To understand differences in sporulation ability between both conditions, Real-time reverse transcription-PCR was used to study the expression the expression of sporulation initiation genes spo0A, spo0B, spo0F, kinA and kinB. The kinetics of gene expression spo0A, spo0B, spo0F and kinA had the same trend. They were characterized by a higher expression in anaerobiosis compared to aerobiosis at the beginning and the end of exponential growth phase. Furthermore, kinB gene expression was characterized by an increase in anaerobiosis compared to aerobiosis to achieve a peak between 4 (middle exponential phase) and 6 (early stationary phase) hours of growth. The spo0A, spo0B, spo0F, kinA and kinB genes are differentially expressed between aerobiosis and anaerobiosis. These data may help to understand the difference in B. cereus sporulation capacity between aerobic and anaerobic condition
46
Tchervenivanova, Eli. "Development of a model to predict sporulation of Bremia lactucae in lettuce". Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23943.
Testo completoAbstract (sommario):
The effect of temperature and duration of leaf wetness (DLW) on sporulation of Bremia lactucae was determined for lettuce cv. Ithaca. A single spore isolate of B. lactucae was produced and was identified using lettuce differential lines each of which had known gene for resistance. Potted lettuce plants were inoculated with the isolate and incubated at 15 C, at 100% relative humidity for 24 h and then at a relative humidity lower than 70%. Seven days later, the plants were submitted to five different temperatures (5, 10, 15, 20 and 25 C) and six durations of leaf wetness (4, 6, 8, 10, 12 and 14 h). The number of spores produced was determined at the end of each wet period. After 4 h of incubation no spores were observed at any of the temperatures. Highest number of spores was found at 10 and 15 C for more than 10 h of DLW. The rate of sporulation rapidly increased between 8 and 10 h for all the temperatures, including 25 C, where the amount of spores produced was very low. The observed number of spores was transformed into proportion of maximum sporulation (PMS) by providing each data by the maximum number of spores observed for each experiment. The Richards model was used to describe sporulation as a function of leaf wetness duration and the rate and maximum value expressed as a function of temperature. This approach resulted in a three-dimensional equation that explained 87% of the variation in the PMS. Spore viability was also estimated for each temperature and DLW. It was zero after 6 h of incubation and reached almost the maximum after 10 h for all the temperatures. The sporulation model was validated under field conditions and it predicted high, medium, low, or no sporulation in 8 out of 11 times.
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Elgadi, Suliman Ali. "Sporulation septation in Streptomyces as a model to investigate bacterial cell division". Thesis, Swansea University, 2012. https://cronfa.swan.ac.uk/Record/cronfa43201.
Testo completoAbstract (sommario):
Streptomyces are interesting gram positive filamentous bacteria and have been studied mostly in the context of antibiotic production. This system is controlled by specific networks of genes through regulatory signals that combine to regulate both morphological and physiological differentiation in the organism. But it is in the context of growth and cell division that they are also fascinating. FtsW is one of four Shape, Elongation, Division and Sporulation (SEDS) family proteins encoded in the genome of S. coelicolor. In this study the effect of ftsW complementation, and its overexpression in S. coelicolor, and role of other related proteins was studied. Complementation of an ftsW mutant resulted in a sporulating phenotype confirming that the white phenotype was due to ftsW disruption, and ftsW function was restored by the complementing plasmid. Macroscopically, fts W or ^/com plem entation or overexpression in S. coelicolor does not show any difference in phenotype. In addition, the microscopic analysis revealed that there is no effect of ftsW or ftsl overexpression on the sporulation septation and chromosomal condensation of aerial hyphae. FtsW localization was investigated revealing a diffuse distribution of fluorescence in the aerial hyphae of an ftsWcomplemented strain, due to in vivo proteolytic cleavage of the FtsW-mCherry translational fusion protein, precluding any inference of FtsW localisation itself. Also mycobacterial orthologs of FtsW and Ftsl cannot replace the function of their related streptomycete proteins. By construction of triple mutants of ftsW, sfr and rodA2 SEDS genes in one strain of S.coelicolor, results showed that these genes are dispensable for growth and survival. No difference was observed between the triple mutant strain that exhibited a white non-sporulating phenotype, and the fts W single mutant phenotype. An absence of sporulation septa in both the triple mutant and ftsW single mutant aerial hyphae, while an sfrlrodA2diO\xb\Q mutant has normal sporulation septa, confirming that FtsW is required specifically for sporulation septation. In contrast and from the results of fluorescence microscopical analysis of the vegetative mycelium of the triple mutant strain and the wild type strain, a similar staining pattern of vegetative septa were observed, suggesting that these genes (ftsW, sfr and rodA2) are not required for vegetative septation in S. coelicolor. In addition, in order to understand the cell division mechanism in S. coelicolor more clearly, the Bacterial Adenylate Cyclase Two- Hybrid (BACTH) system used to study protein-protein interactions. Proteins tested were FtsW, Ftsl, FtsZ, FtsQ, CrgA, Sfr, MreB, RodA, RodA2, penicillin binding proteins PBP1, PBP2 and PBP3) in several combinations of protein pairs. Notably, the results showed a strong interaction between CrgA and FtsQ, and also with other cell division proteins, suggesting aivcentral role for CrgA in the cell division process. According to this significant results, alignment of the S', coelicolor CrgA sequence with orthologs from other Actinobacteria was carried out, revealing only four amino acids G4 0, W45, N65 and Ws3 that are well conserved. After site directed mutagenesis to modify S. coelicolor CrgA, this revealed that the amino acids N65 and Wg3 are required for interaction of the protein with itself and PBP2.
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Dean, Amanda Marie. "Requirements for Compartmentalization of Penicillin-Binding Proteins during Sporulation in Bacillus subtilis". Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/36489.
Testo completoAbstract (sommario):
Penicillin-binding proteins (PBP's) are membrane-associated enzymes involved in the polymerization of peptidoglycan. PBP's are divided into three classes based upon their molecular weights and functional domains. Gene expression is regulated in the two differentiated cells in Bacillus subtilis, the mother cell and the forespore, by coordinated expression of different sigma factors that recognize specific promoters in each compartment. The functional and compartmental specificity of individual penicillin-binding proteins from the different classes of PBP's were examined during sporulation in B. subtilis. Analyses of three class A high molecular weight PBP's indicated that pbpF and pbpG must be expressed in the forespore to carry out their specific role during spore peptidoglycan synthesis. Expressing pbpD in either the forespore or the mother cell could not complement for the loss of pbpF and pbpG, suggesting that there must be additional sequence information in PBP2c and PBP2d that allows them to carry out their specific role during germ cell wall synthesis. Analyses of a low molecular weight PBP, PBP5*, suggested that expressing dacB in either the mother cell or in the forespore could regulate the level of spore peptidoglycan cross-linking to what is typical of wild type spore peptidoglycan.Master of Science
49
Babcock, Martin J. "Characterization and regulation of a gene involved in sporulation of Streptomyces griseus /". The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487676261012572.
Testo completo
50
Rerngsamran, Panan. "Functional analysis of fluffy, a transcriptional regulator for conidial development in Neurospora crassa". Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/2452.
Testo completoAbstract (sommario):
The fluffy gene of Neurospora crassa is required for asexual sporulation. It encodes an 88 kDa polypeptide containing a typical fungal Zn2Cys6 DNA binding motif. To identify the target genes on which FL may act, I sought to identify target sequences to which the FL protein binds. Several strategies were attempted to obtain purified FL protein. Purification was achieved by expressing the DNA binding domain of FL in Escherichia coli as a fusion with glutathione S-transferase followed by affinity purification using glutathione sepharose chromatography. DNA binding sites were selected by in vitro binding assays. Comparison of the sequences of selected clones suggested that FL binds to the motif 5??-CGG(N)9CCG-3??. A potential binding site was found in the promoter region of the eas (ccg-2) gene, which encodes a fungal hydrophobin. In vitro competitive binding assays revealed a preferred binding site for FL in the eas promoter, 5??-CGGAAGTTTCCTCCG-3??, which is located 1498 bp upstream of the eas translation initiation codon. In vivo experiments using a foreign DNA sequence tag confirmed that this sequence is a target site for FL regulation. Using Saccharomyces cerevisiae as an experimental system, I demonstrated that the C-terminal portion of FL functions in transcriptional activation. Microarray analysis was performed to study the role of fl in gene regulation on a large scale. mRNA levels in a fl mutant were compared to those in a strain overexpressing the fl gene. Experiments with cDNA microarray containing 13% of the total number of predicted N. crassa genes revealed 122 genes differentially expressed in response to overexpression of fl. Among these, eas displayed the greatest level of response. The cDNA microarray approach also revealed a number of genes that may be indirectly regulated by fl but may be involved in development. This information provides a foundation for further analysis of the role of fl in conidial development.