Artykuły w czasopismach: „Sporulation”

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Fernández-García, Gemma, Nathaly González-Quiñónez, Beatriz Rioseras, Sergio Alonso-Fernández, Javier Fernández, Felipe Lombó i Ángel Manteca. "The SCO2102 Protein Harbouring a DnaA II Protein-Interaction Domain Is Essential for the SCO2103 Methylenetetrahydrofolate Reductase Positioning at Streptomyces Sporulating Hyphae, Enhancing DNA Replication during Sporulation". International Journal of Molecular Sciences 23, nr 9 (30.04.2022): 4984. http://dx.doi.org/10.3390/ijms23094984.

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Streptomyces DNA replication starts with the DnaA binding to the origin of replication. Differently to most bacteria, cytokinesis only occurs during sporulation. Cytokinesis is modulated by the divisome, an orderly succession of proteins initiated by FtsZ. Here, we characterised SCO2102, a protein harbouring a DnaA II protein–protein interaction domain highly conserved in Streptomyces. The ΔSCO2102 knockout shows highly delayed sporulation. SCO2102-mCherry frequently co-localises with FtsZ-eGFP during sporulation and greatly reduces FtsZ-eGFP Z-ladder formation, suggesting a role of SCO2102 in sporulation. SCO2102 localises up-stream of SCO2103, a methylenetetrahydrofolate reductase involved in methionine and dTMP synthesis. SCO2102/SCO2103 expression is highly regulated, involving two promoters and a conditional transcription terminator. The ΔSCO2103 knockout shows reduced DNA synthesis and a non-sporulating phenotype. SCO2102-mCherry co-localises with SCO2103-eGFP during sporulation, and SCO2102 is essential for the SCO2103 positioning at sporulating hyphae, since SCO2103-eGFP fluorescent spots are absent in the ΔSCO2102 knockout. We propose a model in which SCO2102 positions SCO2103 in sporulating hyphae, facilitating nucleotide biosynthesis for chromosomal replication. To the best of our knowledge, SCO2102 is the first protein harbouring a DnaA II domain specifically found during sporulation, whereas SCO2103 is the first methylenetetrahydrofolate reductase found to be essential for Streptomyces sporulation.

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Ferreira, Julio C., Anita D. Panek i Pedro S. de Araujo. "Inactivation of maltose permease and maltase in sporulatingSaccharomyces cerevisiae". Canadian Journal of Microbiology 46, nr 4 (1.04.2000): 383–86. http://dx.doi.org/10.1139/w99-136.

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Maltose transport and maltase activities were inactivated during sporulation of a MAL constitutive yeast strain harboring different MAL loci. Both activities were reduced to almost zero after 5 h of incubation in sporulation medium. The inactivation of maltase and maltose permease seems to be related to optimal sporulation conditions such as a suitable supply of oxygen and cell concentration in the sporulating cultures, and occurs in the fully derepressed conditions of incubation in the sporulation acetate medium. The inactivation of maltase and maltose permease under sporulation conditions in MAL constitutive strains suggests an alternative mechanism for the regulation of the MAL gene expression during the sporulation process.Key words: maltase activity, maltose permease activity, sporulation, Saccharomyces cerevisiae.

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Edwards, Adrianne N., Kathryn L. Nawrocki i Shonna M. McBride. "Conserved Oligopeptide Permeases Modulate Sporulation Initiation in Clostridium difficile". Infection and Immunity 82, nr 10 (28.07.2014): 4276–91. http://dx.doi.org/10.1128/iai.02323-14.

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ABSTRACTThe anaerobic gastrointestinal pathogenClostridium difficilemust form a metabolically dormant spore to survive in oxygenic environments and be transmitted from host to host. The regulatory factors by whichC. difficileinitiates and controls the early stages of sporulation inC. difficileare not highly conserved in otherClostridiumorBacillusspecies. Here, we investigated the role of two conserved oligopeptide permeases, Opp and App, in the regulation of sporulation inC. difficile. These permeases are known to positively affect sporulation inBacillusspecies through the import of sporulation-specific quorum-sensing peptides. In contrast to other spore-forming bacteria, we discovered that inactivating these permeases inC. difficileresulted in the earlier expression of early sporulation genes and increased sporulationin vitro. Furthermore, disruption ofoppandappresulted in greater virulence and increased the amounts of spores recovered from feces in the hamster model ofC. difficileinfection. Our data suggest that Opp and App indirectly inhibit sporulation, likely through the activities of the transcriptional regulator SinR and its inhibitor, SinI. Taken together, these results indicate that the Opp and App transporters serve a different function in controlling sporulation and virulence inC. difficilethan inBacillus subtilisand suggest that nutrient availability plays a significant role in pathogenesis and sporulationin vivo. This study suggests a link between the nutritional status of the environment and sporulation initiation inC. difficile.

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Hao, Jiang, i Kathleen E. Kendrick. "Visualization of Penicillin-Binding Proteins during Sporulation of Streptomyces griseus". Journal of Bacteriology 180, nr 8 (15.04.1998): 2125–32. http://dx.doi.org/10.1128/jb.180.8.2125-2132.1998.

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ABSTRACT We used fluorescein-tagged β-lactam antibiotics to visualize penicillin-binding proteins (PBPs) in sporulating cultures ofStreptomyces griseus. Six PBPs were identified in membranes prepared from growing and sporulating cultures. The binding activity of an 85-kDa PBP increased fourfold by 10 to 12 h of sporulation, at which time the sporulation septa were formed. Cefoxitin inhibited the interaction of the fluorescein-tagged antibiotics with the 85-kDa PBP and also prevented septum formation during sporulation but not during vegetative growth. The 85-kDa PBP, which was the predominant PBP in membranes of cells that were undergoing septation, preferentially bound fluorescein-6-aminopenicillanic acid (Flu-APA). Fluorescence microscopy showed that the sporulation septa were specifically labeled by Flu-APA; this interaction was blocked by prior exposure of the cells to cefoxitin at a concentration that interfered with septation. We hypothesize that the 85-kDa PBP is involved in septum formation during sporulation of S. griseus.

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Perez, Ana R., Angelica Abanes-De Mello i Kit Pogliano. "Suppression of Engulfment Defects in Bacillus subtilis by Elevated Expression of the Motility Regulon". Journal of Bacteriology 188, nr 3 (1.02.2006): 1159–64. http://dx.doi.org/10.1128/jb.188.3.1159-1164.2006.

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ABSTRACT During Bacillus subtilis sporulation, the transient engulfment defect of spoIIB strains is enhanced by spoVG null mutations and suppressed by spoVS null mutations. These mutations have opposite effects on expression of the motility regulon, as the spoVG mutation reduces and the spoVS mutation increases σD-directed gene expression, cell separation, and autolysis. Elevating σD activity by eliminating the anti-σ factor FlgM also suppresses spoIIB spoVG, and both flgM and spoVS mutations cause continued expression of the σD regulon during sporulation. We propose that peptidoglycan hydrolases induced during motility can substitute for sporulation-specific hydrolases during engulfment. We find that sporulating cells are heterogeneous in their expression of the motility regulon, which could result in phenotypic variation between individual sporulating cells.

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Ozsarac, N., M. J. Straffon, H. E. Dalton i I. W. Dawes. "Regulation of gene expression during meiosis in Saccharomyces cerevisiae: SPR3 is controlled by both ABFI and a new sporulation control element." Molecular and Cellular Biology 17, nr 3 (marzec 1997): 1152–59. http://dx.doi.org/10.1128/mcb.17.3.1152.

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The SPR3 gene encodes a sporulation-specific homolog of the yeast Cdc3/10/11/12 family of bud neck filament proteins. It is expressed specifically during meiosis and sporulation in Saccharomyces cerevisiae. Analysis of the sporulation-specific regulation of SPR3 has shown that it is strongly activated under sporulating conditions but shows low levels of expression under nonsporulating conditions. A palindromic sequence located near the TATA box is essential to the developmental regulation of this gene and is the only element directly activating SPR3 at the right time during sporulation. Within the palindrome is a 9-bp sequence, gNCRCAAA(A/T) (midsporulation element [MSE]), found in the known control regions of three other sporulation genes. A previously identified ABFI element is also needed for activation. The MSE has been shown to activate a heterologous promoter (CYC1) in a sporulation-specific manner. Related sequences, including an association of MSE and ABFI elements, have been found upstream of other genes activated during the middle stage of S. cerevisiae sporulation. One group of these may be involved in spore coat formation or maturation.

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de JONG, A. E. I., R. R. BEUMER i F. M. ROMBOUTS. "Optimizing Sporulation of Clostridium perfringens". Journal of Food Protection 65, nr 9 (1.09.2002): 1457–62. http://dx.doi.org/10.4315/0362-028x-65.9.1457.

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Many sporulation media have been developed for Clostridium perfringens, but none stimulates sporulation for all strains. The aim of our experiments was to develop a sporulation method using Duncan and Strong (DS) medium, which supports sporulation of a wide variety of strains. Different inoculation levels were tested, and the effects of sporulation-promoting substances and acid shock were evaluated. Furthermore, DS medium was compared with other sporulation media. Highest spore numbers in DS medium were obtained with a 10% 24-h fluid thioglycollate broth inoculum (5.0 × 105/ml). Addition of theophylline and replacement of starch by raffinose increased spore yields for some strains, but most strains were not affected (average increases in log N/ml of 0.2 and 0.3, respectively). One strain was enhanced by the addition of bile, but other strains were strongly inhibited (average decrease in log N/ml of 2.5); agar did not influence sporulation. Neither short-time acid exposure nor addition of culture supernatant fluids of well-sporulating strains resulted in higher spore numbers in DS medium. None of the tested methods enhanced sporulation in general; only strain-dependent effects were obtained. Peptone bile theophylline medium was the most promising sporulation medium tested; peptone bile theophylline starch medium yielded highest spore numbers (2.5 × 105/ml), but some strains failed to sporulate. In conclusion, adding theophylline to DS medium may optimize sporulation of C. perfringens, but peptone bile theophylline medium with or without starch is most suitable.

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Adler, Elliot, Imrich Barák i Patrick Stragier. "Bacillus subtilis Locus Encoding a Killer Protein and Its Antidote". Journal of Bacteriology 183, nr 12 (15.06.2001): 3574–81. http://dx.doi.org/10.1128/jb.183.12.3574-3581.2001.

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ABSTRACT We have isolated mutations that block sporulation after formation of the polar septum in Bacillus subtilis. These mutations were mapped to the two genes of a new locus, spoIIS. Inactivation of the second gene,spoIISB, decreases sporulation efficiency by 4 orders of magnitude. Inactivation of the first gene, spoIISA, has no effect on sporulation but it fully restores sporulation of aspoIISB null mutant, indicating that SpoIISB is required only to counteract the negative effect of SpoIISA on sporulation. An internal promoter ensures the synthesis of an excess of SpoIISB over SpoIISA during exponential growth and sporulation. In the absence of SpoIISB, the sporulating cells show lethal damage of their envelope shortly after asymmetric septation, a defect that can be corrected by synthesizing SpoIISB only in the mother cell. However, forced synthesis of SpoIISA in exponentially growing cells or in the forespore leads to the same type of morphological damage and to cell death. In both cases protection against the killing effect of SpoIISA can be provided by simultaneous synthesis of SpoIISB. The spoIIS locus is unique to B. subtilis, and since it is completely dispensable for sporulation its physiological role remains elusive.

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Silvaggi, Jessica M., David L. Popham, Adam Driks, Patrick Eichenberger i Richard Losick. "Unmasking Novel Sporulation Genes in Bacillus subtilis". Journal of Bacteriology 186, nr 23 (1.12.2004): 8089–95. http://dx.doi.org/10.1128/jb.186.23.8089-8095.2004.

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ABSTRACT The Bacillus subtilis transcription factor σE directs the expression of a regulon of 262 genes, but null mutations in only a small fraction of these genes severely impair sporulation. We have previously reported that mutations in seven σE-controlled genes cause a mild (2- to 10-fold) defect in sporulation. In this study, we found that pairwise combinations of some of these seven mutations led to strong synthetic sporulation phenotypes, especially those involving the ytrHI operon and ybaN. Double mutants of ybaN and ytrH and of ybaN and ytrI had >10,000-fold lower sporulation efficiencies than the wild type. Thin-section electron microscopy revealed a block in cortex formation for the ybaN ytrH double mutant and coat defects for the ybaN single and ybaN ytrI double mutants. Sporulating cells of a ybaN ytrI double mutant and of a ybaN ytrHI triple mutant exhibited a pronounced loss of dipicolinic acid (DPA) between hours 8 and 24 of sporulation, in contrast to the constant levels seen for the wild type. An analysis of the spore cortex peptidoglycans of the ybaN ytrI and ybaN ytrHI mutants showed striking decreases in the levels of total muramic acid by hour 24 of sporulation. These data, along with the loss of DPA in the mutants, suggest that the developing spores were unstable and that the cortex underwent degradation late in sporulation. The existence of otherwise hidden sporulation pathways indicates that functional redundancy may mask the role of hitherto unrecognized sporulation genes.

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Eswaramoorthy, Prahathees, Daniel Duan, Jeffrey Dinh, Ashlee Dravis, Seram Nganbiton Devi i Masaya Fujita. "The Threshold Level of the Sensor Histidine Kinase KinA Governs Entry into Sporulation in Bacillus subtilis". Journal of Bacteriology 192, nr 15 (28.05.2010): 3870–82. http://dx.doi.org/10.1128/jb.00466-10.

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ABSTRACT Sporulation in Bacillus subtilis is controlled by a complex gene regulatory circuit that is activated upon nutrient deprivation. The initial process is directed by the phosphorelay, involving the major sporulation histidine kinase (KinA) and two additional phosphotransferases (Spo0F and Spo0B), that activates the master transcription factor Spo0A. Little is known about the initial event and mechanisms that trigger sporulation. Using a strain in which the synthesis of KinA is under the control of an IPTG (isopropyl-β-d-thiogalactopyranoside)-inducible promoter, here we demonstrate that inducing the synthesis of the KinA beyond a certain level leads to the entry of the irreversible process of sporulation irrespective of nutrient availability. Moreover, the engineered cells expressing KinA under a σH-dependent promoter that is similar to but stronger than the endogenous kinA promoter induce sporulation during growth. These cells, which we designated COS (constitutive sporulation) cells, exhibit the morphology and properties of sporulating cells and express sporulation marker genes under nutrient-rich conditions. Thus, we created an engineered strain displaying two cell cycles (growth and sporulation) integrated into one cycle irrespective of culture conditions, while in the wild type, the appropriate cell fate decision is made depending on nutrient availability. These results suggest that the threshold level of the major sporulation kinase acts as a molecular switch to determine cell fate and may rule out the possibility that the activity of KinA is regulated in response to the unknown signal(s).

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Kaback, D. B., i L. R. Feldberg. "Saccharomyces cerevisiae exhibits a sporulation-specific temporal pattern of transcript accumulation". Molecular and Cellular Biology 5, nr 4 (kwiecień 1985): 751–61. http://dx.doi.org/10.1128/mcb.5.4.751-761.1985.

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Cultures of the yeast Saccharomyces cerevisiae that are heterozygous for the mating type (MATa/MAT alpha) undergo synchronous meiosis and spore formation when starved for nitrogen and supplied with a nonfermentable carbon source such as acetate. Haploid and homozygous MAT alpha/MAT alpha and MATa/MATa diploid cells incubated under the same conditions fail to undergo meiosis and are asporogenous. It has not yet been firmly established that gene expression during sporulation is controlled at the level of transcript accumulation. To examine this question, we used cloned genes that encode a variety of "housekeeping" functions to probe Northern blots to assay the appearance of specific transcripts in both sporulating and asporogenous S. cerevisiae. In sporulating cells, each transcript showed a characteristic pattern of accumulation, reaching a maximum relative abundance at one of several different periods. In contrast, in both asporogenous haploid MATa and diploid MAT alpha/MAT alpha cells, all transcripts accumulated with similar kinetics. These results suggest a sporulation-specific pattern for transcript appearance. During these studies, high levels of several different transcripts were observed at unexpected times in sporulating cells. Histone (H)2A and (H)2B1 transcripts, although most abundant during premeiotic DNA synthesis, remained at one-third to one-half maximal levels after its end and were found in mature ascospores. Their appearance at this time is in sharp contrast to vegetative cells in which these histone transcripts are only found just before and during the period of DNA synthesis. Furthermore, transcripts from GAL10 and CDC10 genes, which are believed to be dispensable for sporulation, were much more abundant in sporulating cells than in asporogenous cells and vegetative cells grown on glucose or acetate. The presence of these transcripts did not appear to be due to a general activation of transcription because each accumulated with different kinetics. In addition, the transcript for at least one gene, HO, that is also dispensable for sporulation was not detected. The increased abundance of transcripts from some genes not required for sporulation leads us to propose that genes preferentially expressed during sporulation need not be essential for this differentiation.

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Kaback, D. B., i L. R. Feldberg. "Saccharomyces cerevisiae exhibits a sporulation-specific temporal pattern of transcript accumulation." Molecular and Cellular Biology 5, nr 4 (kwiecień 1985): 751–61. http://dx.doi.org/10.1128/mcb.5.4.751.

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Cultures of the yeast Saccharomyces cerevisiae that are heterozygous for the mating type (MATa/MAT alpha) undergo synchronous meiosis and spore formation when starved for nitrogen and supplied with a nonfermentable carbon source such as acetate. Haploid and homozygous MAT alpha/MAT alpha and MATa/MATa diploid cells incubated under the same conditions fail to undergo meiosis and are asporogenous. It has not yet been firmly established that gene expression during sporulation is controlled at the level of transcript accumulation. To examine this question, we used cloned genes that encode a variety of "housekeeping" functions to probe Northern blots to assay the appearance of specific transcripts in both sporulating and asporogenous S. cerevisiae. In sporulating cells, each transcript showed a characteristic pattern of accumulation, reaching a maximum relative abundance at one of several different periods. In contrast, in both asporogenous haploid MATa and diploid MAT alpha/MAT alpha cells, all transcripts accumulated with similar kinetics. These results suggest a sporulation-specific pattern for transcript appearance. During these studies, high levels of several different transcripts were observed at unexpected times in sporulating cells. Histone (H)2A and (H)2B1 transcripts, although most abundant during premeiotic DNA synthesis, remained at one-third to one-half maximal levels after its end and were found in mature ascospores. Their appearance at this time is in sharp contrast to vegetative cells in which these histone transcripts are only found just before and during the period of DNA synthesis. Furthermore, transcripts from GAL10 and CDC10 genes, which are believed to be dispensable for sporulation, were much more abundant in sporulating cells than in asporogenous cells and vegetative cells grown on glucose or acetate. The presence of these transcripts did not appear to be due to a general activation of transcription because each accumulated with different kinetics. In addition, the transcript for at least one gene, HO, that is also dispensable for sporulation was not detected. The increased abundance of transcripts from some genes not required for sporulation leads us to propose that genes preferentially expressed during sporulation need not be essential for this differentiation.

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Eswaramoorthy, Prahathees, Jeffrey Dinh, Daniel Duan, Oleg A. Igoshin i Masaya Fujita. "Single-cell measurement of the levels and distributions of the phosphorelay components in a population of sporulating Bacillus subtilis cells". Microbiology 156, nr 8 (1.08.2010): 2294–304. http://dx.doi.org/10.1099/mic.0.038497-0.

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Upon nutrient starvation, the Gram-positive bacterium Bacillus subtilis switches from growth to sporulation by activating a multicomponent phosphorelay consisting of a major sensor histidine kinase (KinA), two phosphotransferases (Spo0F and Spo0B) and a response regulator (Spo0A). Although the primary sporulation signal(s) produced under starvation conditions is not known, it is believed that the reception of a signal(s) on the sensor kinase results in the activation of autophosphorylation of the enzyme. The phosphorylated kinase transfers the phosphate group to Spo0A via the phosphorelay and thus triggers sporulation. With a combination of quantitative immunoblot analysis, microscopy imaging and computational analysis, here we found that each of the phosphorelay components tested increased gradually over the period of sporulation, and that Spo0F was expressed in a more heterogeneous pattern than KinA and Spo0B in a sporulating cell population. We determined molecule numbers and concentrations of each phosphorelay component under physiological sporulation conditions at the single-cell level. Based on these results, we suggest that successful entry into the sporulation state is manifested by a certain critical level of each phosphorelay component, and thus that only a subpopulation achieves a sufficient intracellular quorum of the phosphorelay components to activate Spo0A and proceed successfully to the entry into sporulation.

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McVITTIE, ANNE. "Ultrastructural Studies on Sporulation in Wild-type and White Colony Mutants of Streptomyces coelicolor". Microbiology 81, nr 2 (1.02.2000): 291–302. http://dx.doi.org/10.1099/00221287-81-2-291.

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Summary: Examination of thin sections of sporulating wild-type colonies revealed new structural details of the development of the sporulation-septum walls. Spores with very thick (about 75 nm) three-layered walls were seen in spore preparations. Of the sporulation defective (whi) mutants examined, whiDI6 was defective in spore-wall thickening while whiF99 was defective in rounding up and produced rod-shaped, thick-walled spores. A third mutant (whi-92) showed occasional abnormality in sporulation-septum spacing and produced immature as well as mature spores. One mutant (whi-53) produced only a few spores, all structurally normal. In two whiE mutants, structural abnormalities in spores were absent or rare.

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Su, Wanfang, L. R. Beuchat i R. E. Worthington. "Independent development of heat resistance and ascospores of Hansenula anomala". Canadian Journal of Microbiology 31, nr 1 (1.01.1985): 45–49. http://dx.doi.org/10.1139/m85-010.

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The development of ascospores and heat resistance was determined in McClary's acetate broth in the presence of two sporulation inhibitors, ethanol and erythromycin. The inhibitors delayed sporulation without preventing development of heat resistance. The presence of ethanol in growth media caused cells to have increased heat resistance. The fatty acid and chitin contents of sporulating Hansenula anomala cells were determined. Highest triglyceride content of cells was associated with the initiation of sporulation. This phenomenon was not observed for phospholipid. As the ratio of saturated to unsaturated fatty acids in triglycerides increased, so did the heat resistance. However, the chitin content of cells was not correlated with heat resistance.

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Starostzik, C., i W. Marwan. "Kinetic analysis of a signal-transduction pathway by time-resolved somatic complementation of mutants." Journal of Experimental Biology 201, nr 13 (1.07.1998): 1991–99. http://dx.doi.org/10.1242/jeb.201.13.1991.

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Sensory control of sporulation in Physarum polycephalum plasmodia is mediated by a branched signal-transduction pathway that integrates blue light, far-red light, heat shock and the starvation state. Mutants defective in the pathway were isolated and three phenotypes obtained: blue-blind, general-blind and light-independent sporulating. When plasmodia of the blue-blind mutant Blu1 were exposed to a pulse of blue light and subsequently fused to non-induced wild-type plasmodia, the resulting heterokaryons sporulated, indicating a functional blue- light photoreceptor in the mutant. When the general-blind mutant Nos1 was fused to a wild-type plasmodium which had been induced by light, sporulation of the heterokaryon was blocked. However, the dominant inhibition of sporulation by Nos1 was gradually lost with increasing time between induction by light and time of fusion, suggesting that Nos1 can be bypassed by the time-dependent formation of a downstream signal-transduction intermediate. Phenotype expression in constitutively sporulating (Cos) mutants depended on starvation. The Cos2 product was titrated by fusing mutant plasmodia of different sizes to wild-type plasmodia of constant size and analysing the sporulation probability of the resulting heterokaryon. The titration curve indicates that a small change in the amount of Cos2 product can cause sporulation. We conclude that somatic complementation analysis allows the time-resolved evaluation of the regulatory function of mutations in a signal-transduction pathway without prior cloning of the gene. This shortcut allows us to characterize many mutants quickly and to select those for molecular analysis that display a well-defined regulatory function.

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Kemp, Jennifer T., Adam Driks i Richard Losick. "FtsA Mutants of Bacillus subtilis Impaired in Sporulation". Journal of Bacteriology 184, nr 14 (15.07.2002): 3856–63. http://dx.doi.org/10.1128/jb.184.14.3856-3863.2002.

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ABSTRACT Spore formation in Bacillus subtilis involves a switch in the site of cell division from the midcell to a polar position. Both medial division and polar division are mediated in part by the actin-like, cytokinetic protein FtsA. We report the isolation of an FtsA mutant (FtsAD265G) that is defective in sporulation but is apparently unimpaired in vegetative growth. Sporulating cells of the mutant reach the stage of asymmetric division but are partially blocked in the subsequent morphological process of engulfment. As judged by fluorescence microscopy and electron microscopy, the FtsAD265G mutant produces normal-looking medial septa but immature (abnormally thin) polar septa. The mutant was unimpaired in transcription under the control of Spo0A, the master regulator for entry into sporulation, but was defective in transcription under the control of σF, a regulatory protein whose activation is known to depend on polar division. An amino acid substitution at a residue (Y264) adjacent to D265 also caused a defect in sporulation. D265 and Y264 are conserved among endospore-forming bacteria, raising the possibility that these residues are involved in a sporulation-specific protein interaction that facilitates maturation of the sporulation septum and the activation of σF.

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Murakami, Takako, Koki Haga, Michio Takeuchi i Tsutomu Sato. "Analysis of the Bacillus subtilis spoIIIJ Gene and Its Paralogue Gene, yqjG". Journal of Bacteriology 184, nr 7 (1.04.2002): 1998–2004. http://dx.doi.org/10.1128/jb.184.7.1998-2004.2002.

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ABSTRACT The Bacillus subtilis spoIIIJ gene, which has been proven to be vegetatively expressed, has also been implicated as a sporulation gene. Recent genome sequencing information in many organisms reveals that spoIIIJ and its paralogous gene, yqjG, are conserved from prokaryotes to humans. A homologue of SpoIIIJ/YqjG, the Escherichia coli YidC is involved in the insertion of membrane proteins into the lipid bilayer. On the basis of this similarity, it was proposed that the two homologues act as translocase for the membrane proteins. We studied the requirements for spoIIIJ and yqjG during vegetative growth and sporulation. In rich media, the growth of spoIIIJ and yqjG single mutants were the same as that of the wild type, whereas spoIIIJ yqjG double inactivation was lethal, indicating that together these B. subtilis translocase homologues play an important role in maintaining the viability of the cell. This result also suggests that SpoIIIJ and YqjG probably control significantly overlapping functions during vegetative growth. spoIIIJ mutations have already been established to block sporulation at stage III. In contrast, disruption of yqjG did not interfere with sporulation. We further show that high level expression of spoIIIJ during vegetative phase is dispensable for spore formation, but the sporulation-specific expression of spoIIIJ is necessary for efficient sporulation even at the basal level. Using green fluorescent protein reporter to monitor SpoIIIJ and YqjG localization, we found that the proteins localize at the cell membrane in vegetative cells and at the polar and engulfment septa in sporulating cells. This localization of SpoIIIJ at the sporulation-specific septa may be important for the role of spoIIIJ during sporulation.

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Caffi, Tito, Giovanna Gilardi, Matteo Monchiero i Vittorio Rossi. "Production and Release of Asexual Sporangia in Plasmopara viticola". Phytopathology® 103, nr 1 (styczeń 2013): 64–73. http://dx.doi.org/10.1094/phyto-04-12-0082-r.

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To study the influence of environmental conditions on sporulation of Plasmopara viticola lesions under vineyard's conditions, unsprayed vines were inspected every second or third day and the numbers of sporulating and nonsporulating lesions were counted in two North Italy vineyards in 2008 to 2010. Infected leaves were removed so that only fresh lesions were assessed at each field assessment. Sporulation was studied at two scales, across field assessments and across the seasonal population of lesions. Frequencies of sporulating lesions were positively correlated with the numbers of moist hours in the preceding dark period (i.e., the number of hours between 8:00 p.m. and 7:00 a.m. with relative humidity ≥80%, rainfall >0 mm, or wetness duration >30 min). In a receiver operating characteristic analysis, predicted sporulation based on the occurrence of ≥3 moist hours at night provided overall accuracy of 0.85. To study the time course of sporulation on lesions which were not washed by rainfall, numbers of sporangia produced per square millimeter of lesion were estimated on individual cohorts of lesions over the whole infectious period. The numbers of sporangia per square millimeter of lesion increased rapidly during the first 4 days after the beginning of sporulation and then tapered off prior to a halt; the time course of cumulative sporangia production by a lesion followed a monomolecular growth model (R2 = 0.97). The total number of sporangia produced by a square millimeter of lesion increased as the maximum temperature decreased and moist hours in the dark increased. To study the release pattern of the sporangia, spore samplers were placed near grapevines with sporulating lesions. Airborne sporangia were caught in 91.2% of the days over a wide range of weather conditions, including rainless periods. The results of this study provide quantitative information on production of P. viticola sporangia that may help refine epidemiological models used as decision aids in grape disease management programs.

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Jakubowski, H., i E. Goldman. "Evidence for cooperation between cells during sporulation of the yeast Saccharomyces cerevisiae". Molecular and Cellular Biology 8, nr 12 (grudzień 1988): 5166–78. http://dx.doi.org/10.1128/mcb.8.12.5166-5178.1988.

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Diploid Saccharomyces cerevisiae cells heterozygous for the mating type locus (MATa/MAT alpha) undergo meiosis and sporulation when starved for nitrogen in the presence of a poor carbon source such as potassium acetate. Diploid yeast adenine auxotrophs sporulated well at high cell density (10(7) cells per ml) under these conditions but failed to differentiate at low cell density (10(5) cells per ml). The conditional sporulation-deficient phenotype of adenine auxotrophs could be complemented by wild-type yeast cells, by medium from cultures that sporulate at high cell density, or by exogenously added adenine (or hypoxanthine with some mutants). Adenine and hypoxanthine in addition to guanine, adenosine, and numerous nucleotides were secreted into the medium, each in its unique temporal pattern, by sporulating auxotrophic and prototrophic yeast strains. The major source of these compounds was degradation of RNA. The data indicated that differentiating yeast cells cooperate during sporulation in maintaining sufficiently high concentrations of extracellular purines which are absolutely required for sporulation of adenine auxotrophs. Yeast prototrophs, which also sporulated less efficiently at low cell density (10(3) cells per ml), reutilized secreted purines in preference to de novo-made purine nucleotides whose synthesis was in fact inhibited during sporulation at high cell density. Adenine enhanced sporulation of yeast prototrophs at low cell density. The behavior of adenine auxotrophs bearing additional mutations in purine salvage pathway genes (ade apt1, ade aah1 apt1, ade hpt1) supports a model in which secretion of degradation products, uptake, and reutilization of these products is a signal between cells synchronizing the sporulation process.

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21

Jakubowski, H., i E. Goldman. "Evidence for cooperation between cells during sporulation of the yeast Saccharomyces cerevisiae." Molecular and Cellular Biology 8, nr 12 (grudzień 1988): 5166–78. http://dx.doi.org/10.1128/mcb.8.12.5166.

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Diploid Saccharomyces cerevisiae cells heterozygous for the mating type locus (MATa/MAT alpha) undergo meiosis and sporulation when starved for nitrogen in the presence of a poor carbon source such as potassium acetate. Diploid yeast adenine auxotrophs sporulated well at high cell density (10(7) cells per ml) under these conditions but failed to differentiate at low cell density (10(5) cells per ml). The conditional sporulation-deficient phenotype of adenine auxotrophs could be complemented by wild-type yeast cells, by medium from cultures that sporulate at high cell density, or by exogenously added adenine (or hypoxanthine with some mutants). Adenine and hypoxanthine in addition to guanine, adenosine, and numerous nucleotides were secreted into the medium, each in its unique temporal pattern, by sporulating auxotrophic and prototrophic yeast strains. The major source of these compounds was degradation of RNA. The data indicated that differentiating yeast cells cooperate during sporulation in maintaining sufficiently high concentrations of extracellular purines which are absolutely required for sporulation of adenine auxotrophs. Yeast prototrophs, which also sporulated less efficiently at low cell density (10(3) cells per ml), reutilized secreted purines in preference to de novo-made purine nucleotides whose synthesis was in fact inhibited during sporulation at high cell density. Adenine enhanced sporulation of yeast prototrophs at low cell density. The behavior of adenine auxotrophs bearing additional mutations in purine salvage pathway genes (ade apt1, ade aah1 apt1, ade hpt1) supports a model in which secretion of degradation products, uptake, and reutilization of these products is a signal between cells synchronizing the sporulation process.

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Riley, Eammon P., Corinna Schwarz, Alan I. Derman i Javier Lopez-Garrido. "Milestones in Bacillus subtilis sporulation research". Microbial Cell 8, nr 1 (4.01.2021): 1–16. http://dx.doi.org/10.15698/mic2021.01.739.

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Endospore formation has been a rich field of research for more than a century, and has benefited from the powerful genetic tools available in Bacillus subtilis. In this review, we highlight foundational discoveries that shaped the sporulation field, from its origins to the present day, tracing a chronology that spans more than one hundred eighty years. We detail how cell-specific gene expression has been harnessed to investigate the existence and function of intercellular proteinaceous channels in sporulating cells, and we illustrate the rapid progress in our understanding of the cell biology of sporulation in recent years using the process of chromosome translocation as a storyline. Finally, we sketch general aspects of sporulation that remain largely unexplored, and that we envision will be fruitful areas of future research.

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Kawai, Fumitaka, Momoko Shoda, Rie Harashima, Yoshito Sadaie, Hiroshi Hara i Kouji Matsumoto. "Cardiolipin Domains in Bacillus subtilis Marburg Membranes". Journal of Bacteriology 186, nr 5 (1.03.2004): 1475–83. http://dx.doi.org/10.1128/jb.186.5.1475-1483.2004.

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ABSTRACT Recently, use of the cardiolipin (CL)-specific fluorescent dye 10-N-nonyl-acridine orange (NAO) revealed CL-rich domains in the Escherichia coli membrane (E. Mileykovskaya and W. Dowhan, J. Bacteriol. 182: 1172-1175, 2000). Staining of Bacillus subtilis cells with NAO showed that there were green fluorescence domains in the septal regions and at the poles. These fluorescence domains were scarcely detectable in exponentially growing cells of the clsA-disrupted mutant lacking detectable CL. In sporulating cells with a wild-type lipid composition, fluorescence domains were observed in the polar septa and on the engulfment and forespore membranes. Both in the clsA-disrupted mutant and in a mutant with disruptions in all three of the paralogous genes (clsA, ywjE, and ywiE) for CL synthase, these domains did not vanish but appeared later, after sporulation initiation. A red shift in the fluorescence due to stacking of two dye molecules and the lipid composition suggested that a small amount of CL was present in sporulating cells of the mutants. Mass spectrometry analyses revealed the presence of CL in these mutant cells. At a later stage during sporulation of the mutants the frequency of heat-resistant cells that could form colonies after heat treatment was lower. The frequency of sporulation of these cells at 24 h after sporulation initiation was 30 to 50% of the frequency of the wild type. These results indicate that CL-rich domains are present in the polar septal membrane and in the engulfment and forespore membranes during the sporulation phase even in a B. subtilis mutant with disruptions in all three paralogous genes, as well as in the membranes of the medial septa and at the poles during the exponential growth phase of wild-type cells. The results further suggest that the CL-rich domains in the polar septal membrane and engulfment and forespore membranes are involved in sporulation.

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Pak, Julia, i Jacqueline Segall. "Regulation of the Premiddle and Middle Phases of Expression of the NDT80 Gene during Sporulation of Saccharomyces cerevisiae". Molecular and Cellular Biology 22, nr 18 (15.09.2002): 6417–29. http://dx.doi.org/10.1128/mcb.22.18.6417-6429.2002.

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ABSTRACT The NDT80 gene of Saccharomyces cerevisiae, which encodes a global activator of transcription of middle sporulation-specific genes, is first expressed after the activation of early meiotic genes but prior to activation of middle sporulation-specific genes. Both upstream repression sequence 1 (URS1) and mid-sporulation element (MSE) sites are present in the promoter region of the NDT80 gene; these elements have been shown previously to contribute to the regulation of expression of early and middle sporulation-specific genes, respectively, by mediating repression in growing cells and activation at specific times during sporulation. In this study, we have shown that the overlapping windows of URS1- and MSE-mediated repression and activation are responsible for the distinctive premiddle expression pattern of the NDT80 gene. Our data suggest that a Sum1-associated repression complex bound at the NDT80 MSE sites prevents Ime1 tethered at the NDT80 URS1 sites from activating transcription of the NDT80 gene at the time that Ime1-dependent activation of early URS1-regulated meiotic genes is occurring. We propose that a decrease in the efficiency of Sum1-mediated repression as cells progress through the early events of the sporulation program allows the previously inactive Ime1 tethered at the URS1 NDT80 sites to promote a low level of expression of the NDT80 gene. This initial phase of URS1-dependent NDT80 expression is followed by Ndt80-dependent upregulation of its own expression, which requires the MSE NDT80 sites and occurs concomitantly with Ndt80-dependent activation of a set of middle MSE-regulated sporulation-specific genes. Mutation of IME2 prevents expression of NDT80 in sporulating cells. We show in this study that NDT80 is expressed and that middle genes are activated in cells of an Δime2/Δime2 Δsum1/Δsum1 strain in sporulation medium. This suggests that Ime2 activates expression of NDT80 by eliminating Sum1-mediated repression.

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Henriquez, Jose L., David Sugar i Robert A. Spotts. "Induction of Cankers on Pear Tree Branches by Neofabraea alba and N. perennans, and Fungicide Effects on Conidial Production on Cankers". Plant Disease 90, nr 4 (kwiecień 2006): 481–86. http://dx.doi.org/10.1094/pd-90-0481.

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Cankers formed on pear branches after inoculations with mycelia of Neofabraea alba or N. perennans, causal agents of bull's eye rot of pear fruit. The highest proportions of successful infections followed inoculations made in fall and winter. Cankers induced by N. perennans were larger than those induced by N. alba. Small, superficial cankers were obtained after inoculations with conidia of N. perennans on wounded branches of pear trees. Sporulation of both pathogens on mycelial-induced cankers occurred throughout the year, with the largest amount of conidia produced at the end of summer and during fall. Sporulation on cankers induced by N. perennans spanned at least 2 years. Copper sulfate reduced sporulation on cankers induced by N. alba, while copper sulfate, trifloxystrobin, and ziram applied to sporulating cankers reduced germination of conidia of N. perennans.

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Wasserstrom, Lisa, i Jürgen Wendland. "Role of RIM101 for Sporulation at Alkaline pH in Ashbya gossypii". Journal of Fungi 7, nr 7 (30.06.2021): 527. http://dx.doi.org/10.3390/jof7070527.

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Microorganisms need to sense and adapt to fluctuations in the environmental pH. In fungal species, this response is mediated by the conserved pacC/RIM101 pathway. In Aspergillus nidulans, PacC activates alkaline-expressed genes and represses acid-controlled genes in response to alkaline pH and has important functions in regulating growth and conidia formation. In Saccharomyces cerevisiae, the PacC homolog Rim101 is required for adaptation to extracellular pH and to regulate transcription of IME1, the Initiator of MEiosis. S. cerevisiae rim101 mutants are defective in sporulation. In Ashbya gossypii, a filamentous fungus belonging to the family of Saccharomycetaceae, little is known about the role of pH in regulating growth and sporulation. Here, we deleted the AgRIM101 homolog (AFR190C). Our analyses show that Rim101 is important for growth and essential for sporulation at alkaline pH in A. gossypii. Acidic liquid sporulation media were alkalinized by sporulating strains, while the high pH of alkaline media (starting pH = 8.6) was reduced to a pH ~ 7.5 by these strains. However, Agrim101 mutants were unable to sporulate in alkaline media and failed to reduce the initial high pH, while they were capable of sporulation in acidic liquid media in which they increased the pH like the wild type.

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Ufano, Sandra, Pedro San-Segundo, Francisco del Rey i Carlos R. Vázquez de Aldana. "SWM1, a Developmentally Regulated Gene, Is Required for Spore Wall Assembly in Saccharomyces cerevisiae". Molecular and Cellular Biology 19, nr 3 (1.03.1999): 2118–29. http://dx.doi.org/10.1128/mcb.19.3.2118.

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ABSTRACT Meiosis in Saccharomyces cerevisiae is followed by encapsulation of haploid nuclei within multilayered spore walls. Formation of this spore-specific wall requires the coordinated activity of enzymes involved in the biosynthesis of its components. Completion of late events in the sporulation program, leading to spore wall formation, requires the SWM1 gene.SWM1 is expressed at low levels during vegetative growth but its transcription is strongly induced under sporulating conditions, with kinetics similar to those of middle sporulation-specific genes. Homozygous swm1Δ diploids proceed normally through both meiotic divisions but fail to produce mature asci. Consistent with this finding, swm1Δ mutant asci display enhanced sensitivity to enzymatic digestion and heat shock. Deletion ofSWM1 specifically affects the expression of mid-late and late sporulation-specific genes. All of the phenotypes observed are similar to those found for the deletion of SPS1 orSMK1, two putative components of a sporulation-specific MAP kinase cascade. However, epistasis analyses indicate that Swm1p does not form part of the Sps1p-Smk1p-MAP kinase pathway. We propose that Swm1p, a nuclear protein, would participate in a different signal transduction pathway that is also required for the coordination of the biochemical and morphological events occurring during the last phase of the sporulation program.

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Stöver, Axel G., i Adam Driks. "Secretion, Localization, and Antibacterial Activity of TasA, a Bacillus subtilis Spore-Associated Protein". Journal of Bacteriology 181, nr 5 (1.03.1999): 1664–72. http://dx.doi.org/10.1128/jb.181.5.1664-1672.1999.

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ABSTRACT The synthesis and subcellular localization of the proteins that comprise the Bacillus subtilis spore are under a variety of complex controls. To better understand these controls, we have identified and characterized a 31-kDa sporulation protein, called TasA, which is secreted into the culture medium early in sporulation and is also incorporated into the spore. TasA synthesis begins approximately 30 min after the onset of sporulation and requires the sporulation transcription factor genes spo0H and spo0A. The first 81 nucleotides of tasA encode a 27-amino-acid sequence that resembles a signal peptide and which is missing from TasA isolated from a sporulating cell lysate. In B. subtiliscells unable to synthesize the signal peptidase SipW, TasA is not secreted, nor is it incorporated into spores. Cells unable to produce SipW produce a 34-kDa form of TasA, consistent with a failure to remove the N-terminal 27 amino acids. In cells engineered to expresssipW and tasA during exponential growth, TasA migrates as a 31-kDa species and is secreted into the culture medium. These results indicate that SipW plays a crucial role in the export of TasA out of the cell and its incorporation into spores. Although TasA is dispensable for sporulation under laboratory conditions, we find that TasA has a broad-spectrum antibacterial activity. We discuss the possibility that during the beginning of sporulation as well as later, during germination, TasA inhibits other organisms in the environment, thus conferring a competitive advantage to the spore.

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Vieira, André L. G., i Suely L. Gomes. "Global Gene Expression Analysis during Sporulation of the Aquatic Fungus Blastocladiella emersonii". Eukaryotic Cell 9, nr 3 (28.12.2009): 415–23. http://dx.doi.org/10.1128/ec.00312-09.

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ABSTRACTTheBlastocladiella emersoniilife cycle presents a number of drastic biochemical and morphological changes, mainly during two cell differentiation stages: germination and sporulation. To investigate the transcriptional changes taking place during the sporulation phase, which culminates with the production of the zoospores, motile cells responsible for the dispersal of the fungus, microarray experiments were performed. Among the 3,773 distinct genes investigated, a total of 1,207 were classified as differentially expressed, relative to time zero of sporulation, at at least one of the time points analyzed. These results indicate that accurate transcriptional control takes place during sporulation, as well as indicating the necessity for distinct molecular functions throughout this differentiation process. The main functional categories overrepresented among upregulated genes were those involving the microtubule, the cytoskeleton, signal transduction involving Ca2+, and chromosome organization. On the other hand, protein biosynthesis, central carbon metabolism, and protein degradation were the most represented functional categories among downregulated genes. Gene expression changes were also analyzed in cells sporulating in the presence of subinhibitory concentrations of glucose or tryptophan. Data obtained revealed overexpression of microtubule and cytoskeleton transcripts in the presence of glucose, probably causing the shape and motility problems observed in the zoospores produced under this condition. In contrast, the presence of tryptophan during sporulation led to upregulation of genes involved in oxidative stress, proteolysis, and protein folding. These results indicate that distinct physiological pathways are involved in the inhibition of sporulation due to these two classes of nutrient sources.

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Li, Jihong, i Bruce A. McClane. "Evaluating the Involvement of Alternative Sigma Factors SigF and SigG in Clostridium perfringens Sporulation and Enterotoxin Synthesis". Infection and Immunity 78, nr 10 (19.07.2010): 4286–93. http://dx.doi.org/10.1128/iai.00528-10.

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ABSTRACT Clostridium perfringens type A food poisoning is the second most commonly identified bacterial food-borne illness. Sporulation contributes to this disease in two ways: (i) most food-poisoning strains form exceptionally resistant spores to facilitate their survival of food-associated stresses, and (ii) the enterotoxin (CPE) responsible for the symptoms of this food poisoning is synthesized only during sporulation. In Bacillus subtilis, four alternative sigma factors mediate sporulation. The same four sigma factors are encoded by C. perfringens genomes, and two (SigE and SigK) have previously been shown to be necessary for sporulation and CPE production by SM101, a transformable derivative of a C. perfringens food-poisoning strain (K. H. Harry, R. Zhou, L. Kroos, and S. B. Melville, J. Bacteriol. 2009, 191:2728-2742). However, the importance of SigF and SigG for C. perfringens sporulation or CPE production had not yet been assessed. In the current study, after confirming that sporulating wild-type SM101 cultures produce SigF (from a tricistronic operon) and SigG, we prepared isogenic sigF- or sigG-null mutants. Whereas SM101 formed heat-resistant, phase-refractile spores, spore formation was blocked in the sigF- and sigG-null mutants. Complementation fully restored sporulation by both mutants. By use of these mutants and complementing strains, CPE production was shown to be SigF dependent but SigG independent. This finding apparently involved regulation of the production of SigE and SigK, which Harry et al. showed to be necessary for CPE synthesis, by SigF. By combining these findings with those previous results, it is now apparent that all four alternative sigma factors are necessary for C. perfringens sporulation, but only SigE, SigF, and SigK are needed for CPE synthesis.

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Olempska-Beer, Z., i E. Freese. "Initiation of meiosis and sporulation in Saccharomyces cerevisiae does not require a decrease in cyclic AMP". Molecular and Cellular Biology 7, nr 6 (czerwiec 1987): 2141–47. http://dx.doi.org/10.1128/mcb.7.6.2141-2147.1987.

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Meiosis and sporulation of Saccharomyces cerevisiae are initiated in a guanine auxotroph by guanine deprivation (E. Bautz Freese, Z. Olempska-Beer, A. Hartig, and E. Freese, Dev. Biol. 102:438-451, 1984). We used this condition to examine a hypothesis (K. Matsumoto, I. Uno, and T. Ishikawa, Cell 32:417-423, 1983) that initiation of meiosis requires a low level of cAMP. We found that, after guanine deprivation, the intracellular concentration of cAMP transiently decreased not more than 20% and not at all if the cAMP phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) was added to the medium. Under these conditions, at least 76% of the cells sporulated in the absence of IBMX, and almost 100% sporulated in its presence. The sporulating cells continually excreted cAMP and utilized the gluconeogenic carbon source. The cells failed to sporulate efficiently and to form four-spored asci if simultaneously deprived of guanine and carbon. After guanine deprivation in glucose medium, sporulation remained suppressed and intracellular cAMP was unchanged. We conclude that, under conditions of guanine starvation, cAMP deficiency is not required for initiation of meiosis and sporulation, cAMP is produced in excess and excreted to the medium, the cells sporulate better if the cAMP concentration is increased by addition of IBMX, the cells require a gluconeogenic carbon source for complete and efficient sporulation, and suppression of sporulation by glucose is not mediated by cAMP.

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Olempska-Beer, Z., i E. Freese. "Initiation of meiosis and sporulation in Saccharomyces cerevisiae does not require a decrease in cyclic AMP." Molecular and Cellular Biology 7, nr 6 (czerwiec 1987): 2141–47. http://dx.doi.org/10.1128/mcb.7.6.2141.

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Meiosis and sporulation of Saccharomyces cerevisiae are initiated in a guanine auxotroph by guanine deprivation (E. Bautz Freese, Z. Olempska-Beer, A. Hartig, and E. Freese, Dev. Biol. 102:438-451, 1984). We used this condition to examine a hypothesis (K. Matsumoto, I. Uno, and T. Ishikawa, Cell 32:417-423, 1983) that initiation of meiosis requires a low level of cAMP. We found that, after guanine deprivation, the intracellular concentration of cAMP transiently decreased not more than 20% and not at all if the cAMP phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) was added to the medium. Under these conditions, at least 76% of the cells sporulated in the absence of IBMX, and almost 100% sporulated in its presence. The sporulating cells continually excreted cAMP and utilized the gluconeogenic carbon source. The cells failed to sporulate efficiently and to form four-spored asci if simultaneously deprived of guanine and carbon. After guanine deprivation in glucose medium, sporulation remained suppressed and intracellular cAMP was unchanged. We conclude that, under conditions of guanine starvation, cAMP deficiency is not required for initiation of meiosis and sporulation, cAMP is produced in excess and excreted to the medium, the cells sporulate better if the cAMP concentration is increased by addition of IBMX, the cells require a gluconeogenic carbon source for complete and efficient sporulation, and suppression of sporulation by glucose is not mediated by cAMP.

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Li, Jihong, Jianming Chen, Jorge E. Vidal i Bruce A. McClane. "The Agr-Like Quorum-Sensing System Regulates Sporulation and Production of Enterotoxin and Beta2 Toxin by Clostridium perfringens Type A Non-Food-Borne Human Gastrointestinal Disease Strain F5603". Infection and Immunity 79, nr 6 (4.04.2011): 2451–59. http://dx.doi.org/10.1128/iai.00169-11.

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ABSTRACTClostridium perfringenstype A strains producing enterotoxin (CPE) cause one of the most common bacterial food-borne illnesses, as well as many cases of non-food-borne human gastrointestinal disease. Recent studies have shown that an Agr-like quorum-sensing system controls production of chromosomally encoded alpha-toxin and perfringolysin O byC. perfringens, as well as sporulation byClostridium botulinumandClostridium sporogenes. The current study explored whether the Agr-like quorum-sensing system also regulates sporulation and production of two plasmid-encoded toxins (CPE and beta2 toxin) that may contribute to the pathogenesis of non-food-borne human gastrointestinal disease strain F5603. An isogenicagrBnull mutant was inhibited for production of beta2 toxin during vegetative growth and in sporulating culture, providing the first evidence that, inC. perfringens, this system can control production of plasmid-encoded toxins as well as chromosomally encoded toxins. This mutant also showed reduced production of alpha-toxin and perfringolysin O during vegetative growth. Importantly, when cultured in sporulation medium, the mutant failed to efficiently form spores and was blocked for CPE production. Complementation partially or fully reversed all phenotypic changes in the mutant, confirming that they were specifically due to inactivation of theagrlocus. Western blots suggest that this loss of sporulation and sporulation-specific CPE production for theagrBnull mutant involves, at least in part, Agr-mediated regulation of production of Spo0A and alternative sigma factors, which are essential forC. perfringenssporulation.

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Shih, Neng-Jen, i Ronald G. Labbé. "Characterization and distribution of amylases during vegetative cell growth and sporulation ofClostridium perfringens". Canadian Journal of Microbiology 42, nr 7 (1.07.1996): 628–33. http://dx.doi.org/10.1139/m96-086.

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Clostridium perfringens produced eight extracellular and two intracellular amylolytic activities when examined by zymograms following polyacrylamide gel electrophoresis under native conditions. The major intracellular amylase was isolated from vegetative cells of C. perfringens. It possessed an estimated molecular mass of 112 kDa. Sulfhydryl and phenol functional groups were essential to its activity. The amylase was endo-acting on starch and also hydrolyzed pullulan. Polyclonal antisera against a purified extracellular amylase did not cross-react with intracellular amylase and the two amylases were biochemically different. The distribution of extracellular amylolytic activities of sporulating cells was different from that of vegetative cells, whereas the distribution of intracellular amylolytic activities remained identical. A significant increase of a particular amylase (A8) occurred in the extracellular fluid during sporulation compared with that during vegetative growth. Regulation of the excretion of amylase(s) may be sporulation and enterotoxingenicity related.Key words: Clostridium perfringens, amylase, sporulation.

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Yamashita, I., i S. Fukui. "Transcriptional control of the sporulation-specific glucoamylase gene in the yeast Saccharomyces cerevisiae". Molecular and Cellular Biology 5, nr 11 (listopad 1985): 3069–73. http://dx.doi.org/10.1128/mcb.5.11.3069-3073.1985.

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In the yeast Saccharomyces cerevisiae, glucoamylase activity appears specifically in sporulating cells heterozygous for the mating-type locus (MAT). We identified a sporulation-specific glucoamylase gene (SGA) and show that expression of SGA is positively regulated by the mating-type genes, both MATa1 and MAT alpha 2. Northern blot analysis revealed that control of SGA is exerted at the level of RNA production. Expression of SGA or the consequent degradation of glycogen to glucose in cells is not required for meiosis or sporulation, since MATa/MAT alpha diploid cells homozygous for an insertion mutation at SGA still formed four viable ascospores.

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Yamashita, I., i S. Fukui. "Transcriptional control of the sporulation-specific glucoamylase gene in the yeast Saccharomyces cerevisiae." Molecular and Cellular Biology 5, nr 11 (listopad 1985): 3069–73. http://dx.doi.org/10.1128/mcb.5.11.3069.

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In the yeast Saccharomyces cerevisiae, glucoamylase activity appears specifically in sporulating cells heterozygous for the mating-type locus (MAT). We identified a sporulation-specific glucoamylase gene (SGA) and show that expression of SGA is positively regulated by the mating-type genes, both MATa1 and MAT alpha 2. Northern blot analysis revealed that control of SGA is exerted at the level of RNA production. Expression of SGA or the consequent degradation of glycogen to glucose in cells is not required for meiosis or sporulation, since MATa/MAT alpha diploid cells homozygous for an insertion mutation at SGA still formed four viable ascospores.

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Poletto, Tales, Marlove F. B. Muniz, Vinícius S. Fantinel, Renata F. Favaretto, Igor Poletto, Lia R. S. Reiniger i Elena Blume. "Culture Medium, Light Regime and Temperature Affect the Development of Sirosporium diffusum". Journal of Agricultural Science 10, nr 6 (6.05.2018): 310. http://dx.doi.org/10.5539/jas.v10n6p310.

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Sirosporium diffusum is the causal agent of the brown leaf spot disease on pecan trees that seriously damages the foliage of adult plants and seedlings. This fungal species is difficult to grow satisfactorily in a culture medium. Therefore, the aim of this study was to evaluate the effects of different physical conditions on the development of S. diffusum. In the first assay, eight culture media and five light regimes were combined, while in the second, the three treatments that promoted highest sporulation were combined with three temperatures. The trials were conducted in a two-factorial arrangement in a fully randomized design with six replicates. V8, V8CaCO3, and CA media under a 24-h photoperiod produced the highest respective sporulations: 29 × 104, 35 × 104, and 41 × 104 conidia ml-1. The best temperature for sporulation was 20±1 °C for all culture media, especially V8CaCO3 and CA. The best artificial conditions for obtaining good mycelial growth and sporulation consisted of a photoperiod of 24 h, temperature of 20±1 °C and V8CaCO3 or CA culture medium.

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38

Rudge, Simon A., Chun Zhou i JoAnne Engebrecht. "Differential Regulation of Saccharomyces cerevisiae Phospholipase D in Sporulation and Sec14-Independent Secretion". Genetics 160, nr 4 (1.04.2002): 1353–61. http://dx.doi.org/10.1093/genetics/160.4.1353.

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Abstract Saccharomyces cerevisiae Spo14, a phosphatidylcholine-specific, phosphatidylinositol (4,5) bisphosphate-activated phospholipase D (PLD), is essential for meiosis and spore formation. Spo14 is also required for secretion in the absence of the phosphatidylinositol/phosphatidylcholine transfer protein Sec14 (i.e., Sec14-independent secretion). In sporulating cells Spo14 is phosphorylated and relocalized within the cell. In contrast, Spo14 does not relocalize and is not phosphorylated in Sec14-independent secretion. Analysis of a partially phosphatidylinositol (4,5) bisphosphate-activated Spo14 mutant, spo14R894G, revealed that Spo14 function in Sec14-independent secretion, unlike the situation in meiosis, requires fully stimulated PLD activity. Consistent with the differential regulation of Spo14 function during sporulation and secretion, we isolated a mutant allele, spo14-S251P, the product of which is improperly phosphorylated and fails to relocalize and rescue the sporulation phenotype of homozygous spo14 diploids, but supports Sec14-independent secretion. Furthermore, we show that the N-terminal domain of Spo14 is both phosphorylated and sufficient for prospore membrane localization during sporulation. These data indicate that Spo14 phosphorylation and relocalization are essential for the process of sporulation, but dispensable for Sec14-independent secretion. Finally, we demonstrate that Spo14 phosphorylation and relocalization are initiated by nitrogen and glucose limitation and occur independently of the process of meiosis.

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39

Sedgwick, Chantelle, Matthew Rawluk, James Decesare, Sheetal Raithatha, James Wohlschlegel, Paul Semchuk, Michael Ellison, John Yates i David Stuart. "Saccharomyces cerevisiae Ime2 phosphorylates Sic1 at multiple PXS/T sites but is insufficient to trigger Sic1 degradation". Biochemical Journal 399, nr 1 (13.09.2006): 151–60. http://dx.doi.org/10.1042/bj20060363.

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The initiation of DNA replication in Saccharomyces cerevisiae depends upon the destruction of the Clb–Cdc28 inhibitor Sic1. In proliferating cells Cln–Cdc28 complexes phosphorylate Sic1, which stimulates binding of Sic1 to SCFCdc4 and triggers its proteosome mediated destruction. During sporulation cyclins are not expressed, yet Sic1 is still destroyed at the G1-/S-phase boundary. The Cdk (cyclin dependent kinase) sites are also required for Sic1 destruction during sporulation. Sic1 that is devoid of Cdk phosphorylation sites displays increased stability and decreased phosphorylation in vivo. In addition, we found that Sic1 was modified by ubiquitin in sporulating cells and that SCFCdc4 was required for this modification. The meiosis-specific kinase Ime2 has been proposed to promote Sic1 destruction by phosphorylating Sic1 in sporulating cells. We found that Ime2 phosphorylates Sic1 at multiple sites in vitro. However, only a subset of these sites corresponds to Cdk sites. The identification of multiple sites phosphorylated by Ime2 has allowed us to propose a motif for phosphorylation by Ime2 (PXS/T) where serine or threonine acts as a phospho-acceptor. Although Ime2 phosphorylates Sic1 at multiple sites in vitro, the modified Sic1 fails to bind to SCFCdc4. In addition, the expression of Ime2 in G1 arrested haploid cells does not promote the destruction of Sic1. These data support a model where Ime2 is necessary but not sufficient to promote Sic1 destruction during sporulation.

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40

Black, S. H., i Philipp Gerhardt. "“ENDOTROPHIC” SPORULATION". Annals of the New York Academy of Sciences 102, nr 3 (15.12.2006): 755–62. http://dx.doi.org/10.1111/j.1749-6632.1963.tb13674.x.

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41

Steil, Leif, Mónica Serrano, Adriano O. Henriques i Uwe Völker. "Genome-wide analysis of temporally regulated and compartment-specific gene expression in sporulating cells of Bacillus subtilis". Microbiology 151, nr 2 (1.02.2005): 399–420. http://dx.doi.org/10.1099/mic.0.27493-0.

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Temporal and compartment-specific control of gene expression during sporulation in Bacillus subtilis is governed by a cascade of four RNA polymerase subunits. σ F in the prespore and σ E in the mother cell control early stages of development, and are replaced at later stages by σ G and σ K, respectively. Ultimately, a comprehensive description of the molecular mechanisms underlying spore morphogenesis requires the knowledge of all the intervening genes and their assignment to specific regulons. Here, in an extension of earlier work, DNA macroarrays have been used, and members of the four compartment-specific sporulation regulons have been identified. Genes were identified and grouped based on: i) their temporal expression profile and ii) the use of mutants for each of the four sigma factors and a bofA allele, which allows σ K activation in the absence of σ G. As a further test, artificial production of active alleles of the sigma factors in non-sporulating cells was employed. A total of 439 genes were found, including previously characterized genes whose transcription is induced during sporulation: 55 in the σ F regulon, 154 σ E-governed genes, 113 σ G-dependent genes, and 132 genes under σ K control. The results strengthen the view that the activities of σ F, σ E, σ G and σ K are largely compartmentalized, both temporally as well as spatially, and that the major vegetative sigma factor (σ A) is active throughout sporulation. The results provide a dynamic picture of the changes in the overall pattern of gene expression in the two compartments of the sporulating cell, and offer insight into the roles of the prespore and the mother cell at different times of spore morphogenesis.

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42

Newton, M. R., L. L. Kinkel i K. J. Leonard. "Determinants of Density- and Frequency-Dependent Fitness in Competing Plant Pathogens". Phytopathology® 88, nr 1 (styczeń 1998): 45–51. http://dx.doi.org/10.1094/phyto.1998.88.1.45.

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Using mathematical models, we investigated how infection and sporulation characteristics of competing plant pathogens determine the density and frequency dependence of relative fitness. Two models, one for the infection stage and one for the sporulation stage of a pathogen's life cycle, describe reproductive output of pathogen strains in mixture as a function of the strains' population densities. Model parameters include infection and sporulation efficiencies, carrying capacities on leaves for sporulating lesions and spore production, and coefficients of interstrain competitive effects in both life cycle stages. Although the models were originally developed for rust fungi, they are generally applicable to any organism with distinct colonization (e.g., infection) and propagative (e.g., sporulation) life cycle stages. In this work, paired hypothetical strains were assigned equal baseline parameter values. Parameters were then altered one at a time for one or both strains, and relative fitness was calculated over a range of densities and strain frequencies. Except for infection efficiency, the fitness benefit conferred by an advantage in a single parameter was always density dependent. Relative fitness was frequency dependent whenever inter- and intrastrain competitive effects were not equal. These results suggest that the fitness of pathogens in nature is rarely fixed, but, rather, may typically be highly dependent on the densities and frequencies of all coexisting strains in a habitat.

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43

Simchen, Giora, i Yona Kassir. "Genetic regulation of differentiation towards meiosis in the yeast Saccharomyces cerevisiae". Genome 31, nr 1 (1.01.1989): 95–99. http://dx.doi.org/10.1139/g89-018.

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Normally, meiosis and sporulation in Saccharomyces cerevisiae occur only in diploid strains and only when the cells are exposed to starvation conditions. Diploidy is determined by the mating-type system (the genes MAT, RME1, IME1), whereas the starvation signal is transmitted through the adenylate cyclase – protein kinase pathway (the genes CDC25, RAS2, CDC35 (CYR1), BCY1, TPK1, TPK2, TPK3). The two regulatory pathways converge at the gene IME1, which is a positive regulator of meiosis and whose early expression in sporulating cells correlates with the initiation of meiosis. Sites upstream (5′) of IME1 appear to mediate in the repression of the gene by repressors originating from both the mating-type and the cyclase – kinase pathways.Key words: sporulation, mating type, diploidy, adenylate cyclase, cAMP, protein kinase.

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44

FAILLE, CHRISTINE, JEANNE MARIE MEMBRE, MARTINE KUBACZKA i FRANÇOISE GAVINI. "Altered Ability of Bacillus cereus Spores To Grow under Unfavorable Conditions (Presence of Nisin, Low Temperature, Acidic pH, Presence of NaCl) following Heat Treatment during Sporulation". Journal of Food Protection 65, nr 12 (1.12.2002): 1930–36. http://dx.doi.org/10.4315/0362-028x-65.12.1930.

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The effect of thermal treatment on the heat resistance of Bacillus cereus spores and their ability to germinate and grow under more or less adverse conditions during sporulation was investigated. Spores produced by sporulating cells subjected to a mild heat treatment (at a temperature 15°C higher than the growth temperature) were more resistant to heat than were spores produced by untreated cells. Spore germination and growth (the lag time, the maximal growth rate, and the occurrence of a decrease in population) may be greatly affected by adverse environmental conditions brought about by the addition of nisin, low temperatures, acidic pHs, and, to a lesser extent, the addition of NaCl. Furthermore, heat treatments applied to sporulating cells or to mature spores induced a modification of the lag time (interaction of both treatments). Therefore, mild heat treatments applied during sporulation may affect the heat resistance of spores and the ability of these spores to germinate under adverse conditions and may thus increase the risk associated with the presence of spores in lightly processed foods.

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45

Zhao, Yuling, i Stephen B. Melville. "Identification and Characterization of Sporulation-Dependent Promoters Upstream of the Enterotoxin Gene (cpe) of Clostridium perfringens". Journal of Bacteriology 180, nr 1 (1.01.1998): 136–42. http://dx.doi.org/10.1128/jb.180.1.136-142.1998.

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ABSTRACT Three promoter sites (P1, P2, and P3) responsible for the sporulation-associated synthesis of Clostridium perfringensenterotoxin, a common cause of food poisoning in humans and animals, were identified. Nested and internal deletions of the cpepromoter region were made to narrow down the location of promoter elements. To measure the effects of the deletions on the expression ofcpe, translational fusions containing the promoter deletions were made with the gusA gene of Escherichia coli, which codes for β-glucuronidase; E. coli-C. perfringens shuttle vectors carrying the fusions were introduced into C. perfringens by electroporation. In addition, in vitro transcription assays were performed with the cpepromoter region as the DNA template for extracts made from sporulating cells. DNA sequences upstream of P1 were similar to consensus SigK-dependent promoters, while P2 and P3 were similar to consensus SigE-dependent promoters. SigE and SigK are sporulation-associated sigma factors known to be active in the mother cell compartment of sporulating cells of Bacillus subtilis, the same compartment in which enterotoxin is synthesized in C. perfringens.

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46

Trione, E. J., W. M. Hess i V. O. Stockwell. "Growth and sporulation of the dikaryons of the dwarf bunt fungus in wheat plants and in culture". Canadian Journal of Botany 67, nr 6 (1.06.1989): 1671–80. http://dx.doi.org/10.1139/b89-211.

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In the wheat plants infected with dwarf bunt, sporulation occurs only in developing kernels. The dikaryon was isolated from infected kernels and from the rachis of infected spikes. The development of pathogenic hyphae and teliosporogenesis in vivo and in vitro is described. Ultrastructural studies indicated that in vivo teliospore primordia detach from sporogenous hyphae in the hymenium layer and develop into mature teliospores. Teliospores were borne terminally on sporogenous hyphae in vitro. Substances that stimulate hyphal branching and inhibit teliospore formation of the dikaryon were isolated from vegetative wheat tissues but not from bunt-infected spikes containing the sporulating dikaryon. The dikaryon resumed sporulation only when transferred to rich nutrient media without extracts. Extracts from infected wheat spikes containing the sporulating dikaryon induced the vegetative dikaryon to sporulate. The bioregulators involved in these phenomena were not identified. Bioactive extracts had no apparent effect on the growth of the monokaryon. A fluorochrome, mithramycin, was used to detect nuclei in monokaryotic and dikaryotic hyphae. New approaches to bunt control are discussed. Key words: Tilletia caries, Tilletia controversa, monokaryon, teliospores, bioregulators.

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47

Robert, Corinne, Marie-Odile Bancal i Christian Lannou. "Wheat Leaf Rust Uredospore Production and Carbon and Nitrogen Export in Relation to Lesion Size and Density". Phytopathology® 92, nr 7 (lipiec 2002): 762–68. http://dx.doi.org/10.1094/phyto.2002.92.7.762.

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To develop mechanistic yield loss models for biotrophic fungi, we need better account for the export of dry matter, carbon, and nitrogen from the leaf into the spores. Three experiments in controlled environment chambers were performed to study the dynamics of uredospores production of Puccinia triticina on seedling leaves of wheat in relation to time, lesion density, and sporulating surface area. The detrimental effect of lesion density on the sporulation capacity of brown rust lesions was confirmed. When lesion density increased, spores production per lesion strongly decreased. However, our results showed that increasing lesion density also greatly reduces lesion size. A model was developed to summarize these relationships. Our main conclusion is that the density effect on spore production per lesion is accounted for by lesion size. When sporulation was related to the sporulating surface area, it became independent of density. As well, carbon and nitrogen contents of the spores were independent of lesion density. Our data suggest that when nitrogen available in the host is limiting, spore production is reduced but nitrogen content of spores tend to remain stable.

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Nawrocki, Kathryn L., Adrianne N. Edwards, Nadine Daou, Laurent Bouillaut i Shonna M. McBride. "CodY-Dependent Regulation of Sporulation in Clostridium difficile". Journal of Bacteriology 198, nr 15 (31.05.2016): 2113–30. http://dx.doi.org/10.1128/jb.00220-16.

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ABSTRACTClostridium difficilemust form a spore to survive outside the gastrointestinal tract. The factors that trigger sporulation inC. difficileremain poorly understood. Previous studies have suggested that a link exists between nutritional status and sporulation initiation inC. difficile. In this study, we investigated the impact of the global nutritional regulator CodY on sporulation inC. difficilestrains from the historical 012 ribotype and the current epidemic 027 ribotype. Sporulation frequencies were increased in both backgrounds, demonstrating that CodY represses sporulation inC. difficile. The 027codYmutant exhibited a greater increase in spore formation than the 012codYmutant. To determine the role of CodY in the observed sporulation phenotypes, we examined several factors that are known to influence sporulation inC. difficile. Using transcriptional reporter fusions and quantitative reverse transcription-PCR (qRT-PCR) analysis, we found that two loci associated with the initiation of sporulation,oppandsinR, are regulated by CodY. The data demonstrate that CodY is a repressor of sporulation inC. difficileand that the impact of CodY on sporulation and expression of specific genes is significantly influenced by the strain background. These results suggest that the variability of CodY-dependent regulation is an important contributor to virulence and sporulation in current epidemic isolates. This report provides further evidence that nutritional state, virulence, and sporulation are linked inC. difficile.IMPORTANCEThis study sought to examine the relationship between nutrition and sporulation inC. difficileby examining the global nutritional regulator CodY. CodY is a known virulence and nutritional regulator ofC. difficile, but its role in sporulation was unknown. Here, we demonstrate that CodY is a negative regulator of sporulation in two different ribotypes ofC. difficile. We also demonstrate that CodY regulates known effectors of sporulation, Opp and SinR. These results support the idea that nutrient limitation is a trigger for sporulation inC. difficileand that the response to nutrient limitation is coordinated by CodY. Additionally, we demonstrate that CodY has an altered role in sporulation regulation for some strains.

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Wang, Lijuan, John Perpich, Adam Driks i Lee Kroos. "One Perturbation of the Mother Cell Gene Regulatory Network Suppresses the Effects of Another during Sporulation of Bacillus subtilis". Journal of Bacteriology 189, nr 23 (21.09.2007): 8467–73. http://dx.doi.org/10.1128/jb.01285-07.

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ABSTRACT In the mother cell of sporulating Bacillus subtilis, a regulatory network functions to control gene expression. Four transcription factors act sequentially in the order σE, SpoIIID, σK, GerE. σE and σK direct RNA polymerase to transcribe different regulons. SpoIIID and GerE are DNA-binding proteins that activate or repress transcription of many genes. Several negative regulatory loops add complexity to the network. First, transcriptionally active σK RNA polymerase inhibits early sporulation gene expression, resulting in reduced accumulation of σE and SpoIIID late during sporulation. Second, GerE represses sigK transcription, reducing σK accumulation about twofold. Third, SpoIIID represses cotC, which encodes a spore coat protein, delaying its transcription by σK RNA polymerase. Partially circumventing the first feedback loop, by engineering cells to maintain the SpoIIID level late during sporulation, causes spore defects. Here, the effects of circumventing the second feedback loop, by mutating the GerE binding sites in the sigK promoter region, are reported. Accumulation of pro-σK and σK was increased, but no spore defects were detected. Expression of σK-dependent reporter fusions was altered, increasing the expression of gerE-lacZ and cotC-lacZ and decreasing the expression of cotD-lacZ. Because these effects on gene expression were opposite those observed when the SpoIIID level was maintained late during sporulation, cells were engineered to both maintain the SpoIIID level and have elevated sigK expression late during sporulation. This restored the expression of σK-dependent reporters to wild-type levels, and no spore defects were observed. Hence, circumventing the second feedback loop suppressed the effects of perturbing the first feedback loop. By feeding information back into the network, these two loops appear to optimize target gene expression and increase network robustness. Circumventing the third regulatory loop, by engineering cells to express cotC about 2 h earlier than normal, did not cause a detectable spore defect.

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Premdas, Peter David, i Bryce Kendrick. "Seasonal sporulation of some aero-aquatic fungi". Archiv für Hydrobiologie 122, nr 4 (28.10.1991): 479–82. http://dx.doi.org/10.1127/archiv-hydrobiol/122/1991/479.

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