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1
Berlin, V., e C. Yanofsky. "Protein changes during the asexual cycle of Neurospora crassa." Molecular and Cellular Biology 5, n. 4 (aprile 1985): 839–48. http://dx.doi.org/10.1128/mcb.5.4.839.
Testo completoAbstract (sommario):
A method for synchronizing conidiation and isolating large numbers of cells at discrete stages of conidia development is described. Using two-dimensional gel electrophoresis, we analyzed the protein profiles of mycelia, aerial hyphae, and conidia and observed that the concentration of 14 polypeptides increase and 38 decrease during the asexual cycle. Twelve polypeptides were present in extracts of aerial hyphae or conidia, but not mycelia, suggesting that they may be conidiation specific. The protein profiles of mutants defective in conidiation were also analyzed. Differences were detected in the two-dimensional profiles of protein extracts from fluffy and wild-type aerial hyphae. Polyadenylated RNA isolated from wild-type mycelia and conidiating cultures was translated in vitro in a rabbit reticulocyte lysate. Differences were detected in the polypeptide products specified by the two RNA populations, suggesting that changes in steady-state levels of polyadenylated RNAs also occur during conidiation.
2
Berlin, V., e C. Yanofsky. "Protein changes during the asexual cycle of Neurospora crassa". Molecular and Cellular Biology 5, n. 4 (aprile 1985): 839–48. http://dx.doi.org/10.1128/mcb.5.4.839-848.1985.
Testo completoAbstract (sommario):
A method for synchronizing conidiation and isolating large numbers of cells at discrete stages of conidia development is described. Using two-dimensional gel electrophoresis, we analyzed the protein profiles of mycelia, aerial hyphae, and conidia and observed that the concentration of 14 polypeptides increase and 38 decrease during the asexual cycle. Twelve polypeptides were present in extracts of aerial hyphae or conidia, but not mycelia, suggesting that they may be conidiation specific. The protein profiles of mutants defective in conidiation were also analyzed. Differences were detected in the two-dimensional profiles of protein extracts from fluffy and wild-type aerial hyphae. Polyadenylated RNA isolated from wild-type mycelia and conidiating cultures was translated in vitro in a rabbit reticulocyte lysate. Differences were detected in the polypeptide products specified by the two RNA populations, suggesting that changes in steady-state levels of polyadenylated RNAs also occur during conidiation.
3
Hao, R., e J. C. Schmit. "Cloning of the gene for glutamate decarboxylase and its expression during conidiation in Neurospora crassa". Biochemical Journal 293, n. 3 (1 agosto 1993): 735–38. http://dx.doi.org/10.1042/bj2930735.
Testo completoAbstract (sommario):
Neurospora crassa glutamate decarboxylase (GAD) is produced during conidiation and stored in dormant conidia. Polyclonal antibody was generated to GAD that had been purified to homogeneity. The anti-GAD antibody was specific for N. crassa GAD and inhibited GAD activity. The level of GAD protein decreased during conidial germination, indicating that GAD was degraded during this phase of development. The anti-GAD antibody was used to isolate a cDNA clone of GAD from a lambda ZAP cDNA expression library. Escherichia coli containing a plasmid with the cDNA insert produced GAD activity. The cDNA clone contained a 2.6 kbp insert and hybridized to a 2.6 kb mRNA species from conidiating cultures of N. crassa. GAD mRNA was not present in vegetative hyphae. In conidiating cultures, GAD mRNA was first detected when conidia began to appear. The level of GAD mRNA increased as conidiation progressed. This is the first example of the cloning of an enzyme that is regulated at the level of mRNA during the asexual developmental cycle of N. crassa.
4
Mah, Jae-Hyung, e Jae-Hyuk Yu. "Upstream and Downstream Regulation of Asexual Development in Aspergillus fumigatus". Eukaryotic Cell 5, n. 10 (ottobre 2006): 1585–95. http://dx.doi.org/10.1128/ec.00192-06.
Testo completoAbstract (sommario):
ABSTRACT The opportunistic human pathogen Aspergillus fumigatus produces a large quantity of asexual spores (conidia), which are the primary agent causing invasive aspergillosis in immunocompromised patients. We investigated the mechanisms controlling asexual sporulation (conidiation) in A. fumigatus via examining functions of four key regulators, GpaA (Gα), AfFlbA (RGS), AfFluG, and AfBrlA, previously studied in Aspergillus nidulans. Expression analyses of gpaA, AfflbA, AffluG, AfbrlA, and AfwetA throughout the life cycle of A. fumigatus revealed that, while transcripts of AfflbA and AffluG accumulate constantly, the latter two downstream developmental regulators are specifically expressed during conidiation. Both loss-of-function AfflbA and dominant activating GpaAQ204L mutations resulted in reduced conidiation with increased hyphal proliferation, indicating that GpaA signaling activates vegetative growth while inhibiting conidiation. As GpaA is the primary target of AfFlbA, the dominant interfering GpaAG203R mutation suppressed reduced conidiation caused by loss of AfflbA function. These results corroborate the hypothesis that functions of G proteins and RGSs are conserved in aspergilli. We then examined functions of the two major developmental activators AfFluG and AfBrlA. While deletion of AfbrlA eliminated conidiation completely, null mutation of AffluG did not cause severe alterations in A. fumigatus sporulation in air-exposed culture, implying that, whereas the two aspergilli may have a common key downstream developmental activator, upstream mechanisms activating brlA may be distinct. Finally, both AffluG and AfflbA mutants showed reduced conidiation and delayed expression of AfbrlA in synchronized developmental induction, indicating that these upstream regulators contribute to the proper progression of conidiation.
5
Correa, Alejandro, e Deborah Bell-Pedersen. "Distinct Signaling Pathways from the Circadian Clock Participate in Regulation of Rhythmic Conidiospore Development in Neurospora crassa". Eukaryotic Cell 1, n. 2 (aprile 2002): 273–80. http://dx.doi.org/10.1128/ec.1.2.273-280.2002.
Testo completoAbstract (sommario):
ABSTRACT Several different environmental signals can induce asexual spore development (conidiation) and expression of developmentally regulated genes in Neurospora crassa. However, under constant conditions, where no environmental cues for conidiation are present, the endogenous circadian clock in N. crassa promotes daily rhythms in expression of known developmental genes and of conidiation. We anticipated that the same pathway of gene regulation would be followed during clock-controlled conidiation and environmental induction of conidiation and that the circadian clock would need only to control the initial developmental switch. Previous experiments showed that high-level developmental induction of the clock-controlled genes eas (ccg-2) and ccg-1 requires the developmental regulatory proteins FL and ACON-2, respectively, and normal developmental induction of fl mRNA expression requires ACON-2. We demonstrate that the circadian clock regulates rhythmic fl gene expression and that fl rhythmicity requires ACON-2. However, we find that clock regulation of eas (ccg-2) is normal in an fl mutant strain and ccg-1 expression is rhythmic in an acon-2 mutant strain. Together, these data point to the endogenous clock and the environment following separate pathways to regulate conidiation-specific gene expression.
6
Roncal, Tomás, Shandra Cordobés, Olov Sterner e Unai Ugalde. "Conidiation in Penicillium cyclopium Is Induced by Conidiogenone, an Endogenous Diterpene". Eukaryotic Cell 1, n. 5 (ottobre 2002): 823–29. http://dx.doi.org/10.1128/ec.1.5.823-829.2002.
Testo completoAbstract (sommario):
ABSTRACT The filamentous fungus Penicillium cyclopium conidiates in the presence of calcium ions in submerged culture without nutrient limitation according to a precisely timed program. Conidiation could be prematurely induced in a nutritionally sufficient medium which had previously supported growth, suggesting that a metabolite which influenced the process was produced. A diterpenoid with conidiation-inducing activity, conidiogenone, was purified from the culture medium, along with conidiogenol, a putative derivative with delayed activity. Contrary to previous thought, the presence of calcium was demonstrated to only decrease the threshold concentration of conidiogenone required for the induction to proceed. In light of these results, a mechanism of conidiation induction is presented according to which the mycelium produces a conidiation inducer (conidiogenone) that accumulates extracellularly. When a threshold concentration is reached, induction likely takes place by interaction with a specific cellular receptor. The results indicate that conidiogenone is both sufficient and necessary to induce conidiation.
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Roncal, Tomás, e Unai Ugalde. "Conidiation induction in Penicillium". Research in Microbiology 154, n. 8 (ottobre 2003): 539–46. http://dx.doi.org/10.1016/s0923-2508(03)00168-2.
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Pažoutová, Sylvie, Miroslav Kolařík e Renata Kolínská. "Pleomorphic conidiation in Claviceps". Mycological Research 108, n. 2 (febbraio 2004): 126–35. http://dx.doi.org/10.1017/s0953756203009067.
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9
Betina, V. "Photoinduced conidiation inTrichoderma viride". Folia Microbiologica 40, n. 3 (maggio 1995): 219–24. http://dx.doi.org/10.1007/bf02814196.
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Hanlin, Richard T. "Microcycle conidiation–A review". Mycoscience 35, n. 1 (aprile 1994): 113–23. http://dx.doi.org/10.1007/bf02268539.
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Khurana, N., R. K. Saxena, R. Gupta e R. C. Kuhad. "Light-independent conidiation in Trichoderma spp.: a novel approach to microcycle conidiation". World Journal of Microbiology & Biotechnology 9, n. 3 (maggio 1993): 353–56. http://dx.doi.org/10.1007/bf00383079.
Testo completo
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Friedl, Martina A., Christian P. Kubicek e Irina S. Druzhinina. "Carbon Source Dependence and Photostimulation of Conidiation in Hypocrea atroviridis". Applied and Environmental Microbiology 74, n. 1 (2 novembre 2007): 245–50. http://dx.doi.org/10.1128/aem.02068-07.
Testo completoAbstract (sommario):
ABSTRACT Hypocrea atroviridis is frequently used as a photomorphogenetic model due to its ability to conidiate upon exposure to light. Light is thereby believed to be the primary trigger for spore formation. In contrast, we show here that conidiation is primarily carbon source dependent and that illumination plays a catalytic role; of a total of 95 tested carbon sources, only a small set of carbohydrates, polyols, and sugar acids allowed conidiation in darkness, and on most of them, conidiation was significantly more strongly expressed in light. In addition, there are also a number of carbon sources on which H. atroviridis conidiates in darkness, but light does not further stimulate the process. Yet on another small set of carbon sources (l-sorbitol, d-fucose, d- and l-arabinose, and erythritol), H. atroviridis shows better sporulation in darkness than in light. No sporulation was observed on organic acids and amino acids. Mutants with deletions in the two blue-light receptor proteins BLR-1 and BLR-2 generally showed weaker conidiation on a smaller number of carbon sources than did the parental strain, yet they clearly sporulated on 15 and 27 of the 95 carbon sources tested, respectively. Of the carbon sources supporting sporulation, only 11 supported the conidiation of both mutants, suggesting that the BLR-1 and BLR-2 receptors are variously involved in the carbon source-dependent regulation of spore formation. The addition of cyclic AMP, which has been reported to lead to conidiation in darkness, both positively and negatively affected sporulation and resulted in different effects in the parental strain and the two Δblr mutants. Our data show that the carbon source is the prime determinant for conidiation and that it influences the organism's regulation of conidiation by means of BLR-1 and BLR-2 and their cross talk with cyclic AMP.
13
Twumasi-Boateng, Kwame, Yan Yu, Dan Chen, Fabrice N. Gravelat, William C. Nierman e Donald C. Sheppard. "Transcriptional Profiling Identifies a Role for BrlA in the Response to Nitrogen Depletion and for StuA in the Regulation of Secondary Metabolite Clusters in Aspergillus fumigatus". Eukaryotic Cell 8, n. 1 (21 novembre 2008): 104–15. http://dx.doi.org/10.1128/ec.00265-08.
Testo completoAbstract (sommario):
ABSTRACT Conidiation (asexual sporulation) is a key developmental process in filamentous fungi. We examined the gene regulatory roles of the Aspergillus fumigatus developmental transcription factors StuAp and BrlAp during conidiation. Conidiation was completely abrogated in an A. fumigatus ΔbrlA mutant and was severely impaired in a ΔstuA mutant. We determined the full genome conidiation transcriptomes of wild-type and ΔbrlA and ΔstuA mutant A. fumigatus and found that BrlAp and StuAp governed overlapping but distinct transcriptional programs. Six secondary metabolite biosynthetic clusters were found to be regulated by StuAp, while only one cluster exhibited BrlAp-dependent expression. The ΔbrlA mutant, but not the ΔstuA mutant, had impaired downregulation of genes encoding ribosomal proteins under nitrogen-limiting, but not carbon-limiting, conditions. Interestingly, inhibition of the target of rapamycin (TOR) pathway also caused downregulation of ribosomal protein genes in both the wild-type strain and the ΔbrlA mutant. Downregulation of these genes by TOR inhibition was associated with conidiation in the wild-type strain but not in the ΔbrlA mutant. Therefore, BrlAp-mediated repression of ribosomal protein gene expression is not downstream of the TOR pathway. Furthermore, inhibition of ribosomal protein gene expression is not sufficient to induce conidiation in the absence of BrlAp.
14
Kothe, Gregory O., e Stephen J. Free. "The Isolation and Characterization of nrc-1 and nrc-2, Two Genes Encoding Protein Kinases That Control Growth and Development in Neurospora crassa". Genetics 149, n. 1 (1 maggio 1998): 117–30. http://dx.doi.org/10.1093/genetics/149.1.117.
Testo completoAbstract (sommario):
Abstract Using an insertional mutagenesis approach, a series of Neurospora crassa mutants affected in the ability to control entry into the conidiation developmental program were isolated. One such mutant, GTH16-T4, was found to lack normal vegetative hyphae and to undergo constitutive conidiation. The affected gene has been named nrc-1, for nonrepressible conidiation gene #1. The nrc-1 gene was cloned from the mutant genomic DNA by plasmid rescue, and was found to encode a protein closely related to the protein products of the Saccharomyces cerevisiae STE11 and Schizosaccharomyces pombe byr2 genes. Both of these genes encode MAPKK kinases that are necessary for sexual development in these organisms. We conclude the nrc-1 gene encodes a MAPKK kinase that functions to repress the onset of conidiation in N. crassa. A second mutant, GTH16-T17, was found to lack normal vegetative hyphae and to constitutively enter, but not complete, the conidiation program. The affected locus is referred to as nrc-2 (nonrepressible conidiation gene #2). The nrc-2 gene was cloned and found to encode a serine-threonine protein kinase. The kinase is closely related to the predicted protein products of the S. pombe kad5, and the S. cerevisiae YNRO47w and KIN82 genes, three genes that have been identified in genome sequencing projects. The N. crassa nrc-2 gene is the first member of this group of kinases for which a phenotype has been defined. We conclude a functional nrc-2-encoded serine/threonine kinase is required to repress entry into the conidiation program.
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Kamp, Andrena M., e Michael J. Bidochka. "Protein analysis in a pleomorphically deteriorated strain of the insect-pathogenic fungus Metarhizium anisopliae". Canadian Journal of Microbiology 48, n. 9 (1 settembre 2002): 787–92. http://dx.doi.org/10.1139/w02-074.
Testo completoAbstract (sommario):
Pleomorphic deterioration is a process where a fungal isolate loses the ability to produce conidia during repeated subculturing. We have previously isolated strains of the entomopathogenic fungus Metarhizium anisopliae that have irreversibly lost the ability to produce conidia and only produce mycelia when grown on agar. Gel electrophoresis was used to examine differences in intracellular protein patterns (urea-soluble proteins and urea-insoluble proteins (i.e., hydrophobins)) in conidiating and mycelial cultures of M. anisopliae. Two major proteins present in a conidiating culture and one from a mycelial culture were N-terminally sequenced but showed no homologies to known proteins. The presence of hydrophobins in conidiating and mycelial cultures was also examined, and it was shown that these proteins were abundant in conidiating cultures but not in mycelial cultures. We also used primers designed from regulatory genes involved in conidiation in Aspergillus nidulans. The amplified fragments were not homologous to A. nidulans genes.Key words: Metarhizium anisopliae, conidia, pleomorphic deterioration, protein analysis.
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Yamashiro, C. T., D. J. Ebbole, B. U. Lee, R. E. Brown, C. Bourland, L. Madi e C. Yanofsky. "Characterization of rco-1 of Neurospora crassa, a pleiotropic gene affecting growth and development that encodes a homolog of Tup1 of Saccharomyces cerevisiae." Molecular and Cellular Biology 16, n. 11 (novembre 1996): 6218–28. http://dx.doi.org/10.1128/mcb.16.11.6218.
Testo completoAbstract (sommario):
The filamentous fungus Neurospora crassa undergoes a well-defined developmental program, conidiation, that culminates in the production of numerous asexual spores, conidia. Several cloned genes, including con-10, are expressed during conidiation but not during mycelial growth. Using a previously described selection strategy, we isolated mutants that express con-10 during mycelial growth. Selection was based on expression of an integrated DNA fragment containing the con-10 promoter-regulatory region followed by the initial segment of the con-10 open reading frame fused in frame with the bacterial hygromycin B phosphotransferase structural gene (con10'-'hph). Resistance to hygromycin results from mutational alterations that allow mycelial expression of the con-10'-'hph gene fusion. A set of drug-resistant mutants were isolated; several of these had abnormal conidiation phenotypes and were trans-acting, i.e., they allowed mycelial expression of the endogenous con-10 gene. Four of these had alterations at a single locus, designated rco-1 (regulation of conidiation). Strains with the rco-1 mutant alleles were aconidial, female sterile, had reduced growth rates, and formed hyphae that coiled in a counterclockwise direction, opposite that of the wild type. The four rco-1 mutants had distinct conidiation morphologies, suggesting that conidiation was blocked at different stages. Wild-type rco-1 was cloned by a novel procedure employing heterokaryon-assisted transformation and ligation-mediated PCR. The predicted RCO1 polypeptide is a homolog of Tup1 of Saccharomyces cerevisiae, a multidomain protein that mediates transcriptional repression of genes concerned with a variety of processes. Like tup1 mutants, null mutants of rco-1 are viable and pleiotropic. A promoter element was identified that could be responsible for RCO1-mediated vegetative repression of con-10 and other conidiation genes.
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Li, Bo, Yanping Fu, Daohong Jiang, Jiatao Xie, Jiasen Cheng, Guoqing Li, Mahammad Imran Hamid e Xianhong Yi. "Cyclic GMP as a Second Messenger in the Nitric Oxide-Mediated Conidiation of the Mycoparasite Coniothyrium minitans". Applied and Environmental Microbiology 76, n. 9 (5 marzo 2010): 2830–36. http://dx.doi.org/10.1128/aem.02214-09.
Testo completoAbstract (sommario):
ABSTRACT Understanding signaling pathways that modulate conidiation of mitosporic fungi is of both practical and theoretical importance. The enzymatic origin of nitric oxide (NO) and its roles in conidiation by the sclerotial parasite Coniothyrium minitans were investigated. The activity of a nitric oxide synthase-like (NOS-like) enzyme was detected in C. minitans as evidenced by the conversion of l-arginine to l-citrulline. Guanylate cyclase (GC) activity was also detected indirectly in C. minitans with the GC-specific inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), which significantly reduced production of cyclic GMP (cGMP). The dynamics of NOS activity were closely mirrored by the cGMP levels during pycnidial development, with the highest levels of both occurring at the pycnidial initiation stage of C. minitans. Furthermore, the NO donor, sodium nitroprusside (SNP), stimulated the accumulation of cGMP almost instantly in mycelium during the hyphal growth stage. When the activity of NOS or GC was inhibited with Nω-nitro-l-arginine or ODQ, conidial production of C. minitans was suppressed or completely eliminated; however, the suppression of conidiation by ODQ could be reversed by exogenous cGMP. The results also showed that conidiation of an l-arginine auxotroph could be restored by the NO donor SNP, but not by cGMP. Thus, NO-mediated conidiation has more than one signal pathway, including the cGMP signal pathway and another yet-unknown pathway, and both are essential for conidiation in C. minitans.
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Yager, Lawrence N., Hyung-Ok Lee, Deborah L. Nagle e John E. Zimmerman. "Analysis of fluG Mutations That Affect Light-Dependent Conidiation in Aspergillus nidulans". Genetics 149, n. 4 (1 agosto 1998): 1777–86. http://dx.doi.org/10.1093/genetics/149.4.1777.
Testo completoAbstract (sommario):
Abstract Conidiation in Aspergillus nidulans is induced by exposure to red light but can also be induced by blue light in certain mutant strains. We have isolated a mutation in the fluG gene that abolishes responsiveness to red light but does not affect the response to blue light. It has been shown that the veA1 (velvet) mutation allows conidiation to occur in the absence of light. We have identified three other fluG mutations that suppress the veA1 phenotype; these double mutants do not conidiate in the dark. The mutations described here define two new phenotypic classes of fluG alleles that display abnormal responses to light. We have characterized these mutations with respect to their molecular identity and to their effect on fluG transcription. Although it has been shown that fluG is required for the synthesis of an extracellular factor that directs conidiation, we do not detect this factor under conditions that promote conidiation in the veA1 suppressors. Furthermore, extracellular rescue is not observed in fluG deletion strains containing the wild-type veA allele. We propose that a genetic interaction between fluG and veA influences the production of the extracellular signal and regulates the initiation of conidiation.
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Suzuki, Sakura, Satoshi Katagiri e Hideaki Nakashima. "Mutants With Altered Sensitivity to a Calmodulin Antagonist Affect the Circadian Clock in Neurospora crassa". Genetics 143, n. 3 (1 luglio 1996): 1175–80. http://dx.doi.org/10.1093/genetics/143.3.1175.
Testo completoAbstract (sommario):
Abstract Two newly isolated mutant strains of Neurospora crassa, cpz-1 and cpz-2, were hypersensitive to chlorpromazine with respect to mycelial growth but responded differently to the drug with respect to the circadian conidiation rhythm. In the wild type, chlorpromazine caused shortening of the period length of the conidiation rhythm. Pulse treatment with the drug shifted the phase and inhibited light-induced phase shifting in Neurospora. By contrast to the wild type, the cpz-2 strain was resistant to these inhibitory effects of chlorpromazine. Inhibition of cpz-2 function by chlorpromazine affected three different parameters of circadian conidiation rhythm, namely, period length, phase and light-induced phase shifting. These results indicate that the cpz-2 gene must be involved in or related closely to the clock mechanism of Neurospora. By contrast, the cpz-1 strain was hypersensitive to chlorpromazine with respect to the circadian conidiation rhythm.
20
Kays, Ann M., Patricia S. Rowley, Rudeina A. Baasiri e Katherine A. Borkovich. "Regulation of Conidiation and Adenylyl Cyclase Levels by the Gα Protein GNA-3 in Neurospora crassa". Molecular and Cellular Biology 20, n. 20 (15 ottobre 2000): 7693–705. http://dx.doi.org/10.1128/mcb.20.20.7693-7705.2000.
Testo completoAbstract (sommario):
ABSTRACT We have identified a new gene encoding the G protein α subunit,gna-3, from the filamentous fungusNeurospora crassa. The predicted amino acid sequence of GNA-3 is most similar to the Gα proteins MOD-D, MAGA, and CPG-2 from the saprophytic fungus Podospora anserina and the pathogenic fungi Magnaporthe grisea and Cryphonectria parasitica, respectively. Deletion of gna-3 leads to shorter aerial hyphae and premature, dense conidiation during growth on solid medium or in standing liquid cultures and to inappropriate conidiation in submerged culture. The conidiation and aerial hypha defects of the Δgna-3 strain are similar to those of a previously characterized adenylyl cyclase mutant, cr-1. Supplementation with cyclic AMP (cAMP) restores wild-type morphology to Δgna-3 strains in standing liquid cultures. Solid medium augmented with exogenous cAMP suppresses the premature conidiation defect, but aerial hypha formation is still reduced. Submerged-culture conidiation is refractory to cAMP but is suppressed by peptone. In addition, Δgna-3 submerged cultures express the glucose-repressible gene, qa-2, to levels greatly exceeding those observed in the wild type under carbon-starved conditions. Δgna-3 strains exhibit reduced fertility in homozygous crosses during the sexual cycle; exogenous cAMP has no effect on this phenotype. Intracellular steady-state cAMP levels of Δgna-3 strains are decreased 90% relative to the wild type under a variety of growth conditions. Reduced intracellular cAMP levels in the Δgna-3 strain correlate with lower adenylyl cyclase activity and protein levels. These results demonstrate that GNA-3 modulates conidiation and adenylyl cyclase levels in N. crassa.
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Mat’at’a, Matej, Helena Galádová, L’udovít Varečka e Martin Šimkovič. "The study of intracellular and secreted high-molecular-mass protease(s) of Trichoderma spp., and their responses to conidiation stimuli". Canadian Journal of Microbiology 65, n. 9 (settembre 2019): 653–67. http://dx.doi.org/10.1139/cjm-2018-0670.
Testo completoAbstract (sommario):
We continued our study of high-molecular-mass proteases (HMMPs) using several strains of the genus Trichoderma, and other filamentous fungi (Botrytis cinerea, Aspergillus niger, Fusarium culmorum, and Penicillium purpurogenum). We found that five Trichoderma strains secreted HMMPs into the media after induction with bovine serum albumin. Botrytis cinerea and F. culmorum secreted proteases in the absence of inducer, while A. niger or P. purpurogenum did not secrete proteolytic activity (PA). The activity of HMMPs secreted by or intracellularly located in Trichoderma spp. represents the predominant part of cellular PA, according to zymogram patterns. This observation allowed the study of HMMPs’ physiological role(s) independent from the secretion. In studying conidiation, we found that illumination significantly stimulated PA in Trichoderma strains. In the T. atroviride IMI 206040 strain, we demonstrated that this stimulation is dependent on the BLR1 and BLR2 receptors. No stimulation of PA was observed when mechanical injury was used as an elicitor of conidiation. Compounds used as inhibitors or activators of conidiation exerted no congruent effects on both PA and conidiation. These results do not favour a direct role of HMMPs in conidiation. Probably, HMMP activity may be involved in the process of the activation of metabolism during vegetative growth, differentiation, and aging-related processes.
22
Seo, Jeong-Ah, Yajun Guan e Jae-Hyuk Yu. "Suppressor Mutations Bypass the Requirement of fluG for Asexual Sporulation and Sterigmatocystin Production in Aspergillus nidulans". Genetics 165, n. 3 (1 novembre 2003): 1083–93. http://dx.doi.org/10.1093/genetics/165.3.1083.
Testo completoAbstract (sommario):
Abstract Asexual sporulation (conidiation) in the filamentous fungus Aspergillus nidulans requires the early developmental activator fluG. Loss of fluG results in the blockage of both conidiation and production of the mycotoxin sterigmatocystin (ST). To investigate molecular mechanisms of fluG-dependent developmental activation, 40 suppressors of fluG (SFGs) that conidiate without fluG have been isolated and characterized. Genetic analyses showed that an individual suppression is caused by a single second-site mutation, and that all sfg mutations but one are recessive. Pairwise meiotic crosses grouped mutations to four loci, 31 of them to sfgA, 6 of them to sfgB, and 1 each to sfgC and sfgD, respectively. The only dominant mutation, sfgA38, also mapped to the sfgA locus, suggesting a dominant negative mutation. Thirteen sfgA and 1 sfgC mutants elaborated conidiophores in liquid submerged culture, indicating that loss of either of these gene functions not only bypasses fluG function but also results in hyperactive conidiation. While sfg mutants show varying levels of restored conidiation, all recovered the ability to produce ST at near wild-type levels. The fact that at least four loci are defined by recessive sfg mutations indicates that multiple genes negatively regulate conidiation downstream of fluG and that the activity of fluG is required to remove such repressive effects.
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Jung, Boknam, Soyeon Kim e Jungkwan Lee. "Microcyle Conidiation in Filamentous Fungi". Mycobiology 42, n. 1 (marzo 2014): 1–5. http://dx.doi.org/10.5941/myco.2014.42.1.1.
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Latgé, J. P., R. L. Cabrera Cabrera e M. C. Prévost. "Microcycle conidiation in Hirsutella thompsonii". Canadian Journal of Microbiology 34, n. 5 (1 maggio 1988): 625–30. http://dx.doi.org/10.1139/m88-103.
Testo completoAbstract (sommario):
A fermenter method for producing conidiospores of the acarine pathogen, Hirsutella thompsonii, was developed using a strain able to produce microcycle conidiation in submerged culture. The morphological changes occurring during microcycle formation were followed under electron microscopy. Growth and sporulation patterns of the fungus were examined in batch culture. An average of 2–5 × 108 spores/mL was obtained after 3 days of growth.
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Son, Hokyoung, Myung-Gu Kim, Kyunghun Min, Jae Yun Lim, Gyung Ja Choi, Jin-Cheol Kim, Suhn-Kee Chae e Yin-Won Lee. "WetA Is Required for Conidiogenesis and Conidium Maturation in the Ascomycete Fungus Fusarium graminearum". Eukaryotic Cell 13, n. 1 (1 novembre 2013): 87–98. http://dx.doi.org/10.1128/ec.00220-13.
Testo completoAbstract (sommario):
ABSTRACTFusarium graminearum, a prominent fungal pathogen that infects major cereal crops, primarily utilizes asexual spores to spread disease. To understand the molecular mechanisms underlying conidiogenesis inF. graminearum, we functionally characterized theF. graminearumortholog ofAspergillus nidulanswetA, which has been shown to be involved in conidiogenesis and conidium maturation. Deletion ofF. graminearumwetAdid not alter mycelial growth, sexual development, or virulence, but thewetAdeletion mutants produced longer conidia with fewer septa, and the conidia were sensitive to acute stresses, such as oxidative stress and heat stress. Furthermore, the survival rate of aged conidia from theF. graminearumwetAdeletion mutants was reduced. ThewetAdeletion resulted in vigorous generation of single-celled conidia through autophagy-dependent microcycle conidiation, indicating that WetA functions to maintain conidial dormancy by suppressing microcycle conidiation inF. graminearum. Transcriptome analyses demonstrated that most of the putative conidiation-related genes are expressed constitutively and that only a few genes are specifically involved inF. graminearumconidiogenesis. The conserved and distinct roles identified for WetA inF. graminearumprovide new insights into the genetics of conidiation in filamentous fungi.
26
Krüger, Miriam, e Reinhard Fischer. "Isolation of Two apsA Suppressor Strains in Aspergillus nidulans". Genetics 144, n. 2 (1 ottobre 1996): 533–40. http://dx.doi.org/10.1093/genetics/144.2.533.
Testo completoAbstract (sommario):
Abstract Aspergillus nidulans reproduces asexually with single nucleated conidia. In apsA (anucleate primary sterigmata) strains, nuclear positioning is affected and conidiation is greatly reduced. To get further insights into the cellular functions of apSA, aconidial apsA strains were mutagenized and conidiating suppressor strains were isolated. The suppressors fell into two complementation groups, samA and samB (suppressor of anucleate metulae). samA mapped on linkage group I close to pyrG. The mutant allele was dominant in diploids homozygous for apsA. Viability of conidia of samA suppressor strains (samA −; apsA −) was reduced to 50% in comparison to wild-type conidia. Eighty percent of viable spores produced small size colonies that were temperature- and benomyl-sensitive. samB mapped to chromosome VIII and was recessive. Viability of conidia from samB suppressor strains (apSA −; samB−) was also affected but no small size colonies were observed. Both suppressors produced partial defects in sexual reproduction and both suppressed an apsA deletion mutation. In wild-type background the mutant loci affected hyphal growth rate (samA) or changed the colony morphology (samB) and inhibited sexual spore formation (samA and samB). Only subtle effects on conidiation were found. We conclude that both suppressor genes bypass the apsA function and are involved in microtubule-dependent processes.
27
Sigl, Claudia, Hubertus Haas, Thomas Specht, Kristian Pfaller, Hubert Kürnsteiner e Ivo Zadra. "Among Developmental Regulators, StuA but Not BrlA Is Essential for Penicillin V Production inPenicillium chrysogenum". Applied and Environmental Microbiology 77, n. 3 (10 dicembre 2010): 972–82. http://dx.doi.org/10.1128/aem.01557-10.
Testo completoAbstract (sommario):
ABSTRACTIn filamentous fungi, secondary metabolism is often linked with developmental processes such as conidiation. In this study we analyzed the link between secondary metabolism and conidiation in the main industrial producer of the β-lactam antibiotic penicillin, the ascomycetePenicillium chrysogenum. Therefore, we generated mutants defective in two central regulators of conidiation, the transcription factors BrlA and StuA. Inactivation of eitherbrlAorstuAblocked conidiation and altered hyphal morphology during growth on solid media, as shown by light and scanning electron microscopy, but did not affect biomass production during liquid-submerged growth. Genome-wide transcriptional profiling identified a complex StuA- and BrlA-dependent regulatory network, including genes previously shown to be involved in development and secondary metabolism. Remarkably, inactivation ofstuA, but notbrlA, drastically downregulated expression of the penicillin biosynthetic gene cluster during solid and liquid-submerged growth. In agreement, penicillin V production was wild-type-like inbrlA-deficient strains but 99% decreased instuA-deficient strains during liquid-submerged growth, as shown by high-performance liquid chromatography (HPLC) analysis. Thus, among identified regulators of penicillin V production StuA has the most severe influence. Overexpression ofstuAincreased the transcript levels ofbrlAandabaA(another developmental regulator) and derepressed conidiation during liquid-submerged growth but did not affect penicillin V productivity. Taken together, these data demonstrate an intimate but not exclusive link between regulation of development and secondary metabolism inP. chrysogenum.
28
Chang, Perng-Kuang, Leslie L. Scharfenstein, Brian Mack e Kenneth C. Ehrlich. "Deletion of the Aspergillus flavus Orthologue ofA. nidulans fluGReduces Conidiation and Promotes Production of Sclerotia but Does Not Abolish Aflatoxin Biosynthesis". Applied and Environmental Microbiology 78, n. 21 (17 agosto 2012): 7557–63. http://dx.doi.org/10.1128/aem.01241-12.
Testo completoAbstract (sommario):
ABSTRACTThefluGgene is a member of a family of genes required for conidiation and sterigmatocystin production inAspergillus nidulans. We examined the role of theAspergillus flavus fluGorthologue in asexual development and aflatoxin biosynthesis. Deletion offluGinA. flavusyielded strains with an approximately 3-fold reduction in conidiation but a 30-fold increase in sclerotial formation when grown on potato dextrose agar in the dark. The concurrent developmental changes suggest thatA. flavusFluG exerts opposite effects on a mutual signaling pathway for both processes. The altered conidial development was in part attributable to delayed expression ofbrlA, a gene controlling conidiophore formation. Unlike the loss of sterigmatocystin production byA. nidulans fluGdeletion strains, aflatoxin biosynthesis was not affected by thefluGdeletion inA. flavus. InA. nidulans, FluG was recently found to be involved in the formation of dehydroaustinol, a component of a diffusible signal of conidiation. Coculturing experiments did not show a similar diffusible meroterpenoid secondary metabolite produced byA. flavus. These results suggest that the function offluGand the signaling pathways related to conidiation are different in the two related aspergilli.
29
Liu, Shaohua, e Ralph A. Dean. "G Protein α Subunit Genes Control Growth, Development, and Pathogenicity of Magnaporthe grisea". Molecular Plant-Microbe Interactions® 10, n. 9 (dicembre 1997): 1075–86. http://dx.doi.org/10.1094/mpmi.1997.10.9.1075.
Testo completoAbstract (sommario):
Three G protein α subunit genes have been cloned and characterized from Magnaporthe grisea: magA is very similar to CPG-2 of Cryphonectria parasitica; magB is virtually identical to CPG-1 of Cryphonectria parasitica, to gna1 of Neurospora crassa, and to fadA of Emericella nidulans; and magC is most similar to gna2 of Neurospora crassa. Homologous recombination resulting in targeted deletion of magA had no effect on vegetative growth, conidiation, or appressorium formation. Deletion of magC reduced conidiation, but did not affect vegetative growth or appressorium formation. However, disruption of magB significantly reduced vegetative growth, conidiation, and appressorium formation. magB¯ transformants, unlike magA¯ and magC¯ transformants, exhibited a reduced ability to infect and colonize susceptible rice leaves. G protein α subunit genes are required for M. grisea mating. magB¯ transformants failed to form perithecia, whereas magA¯ and magC¯ transformants did not produce mature asci. These results suggest that G protein α subunit genes are involved in signal transduction pathways in M. grisea that control vegetative growth, conidiation, conidium attachment, appressorium formation, mating, and pathogenicity.
30
Hou, Xingrong, Bang An, Qiannan Wang, Yunfeng Guo, Hongli Luo e Chaozu He. "SGE1 is involved in conidiation and pathogenicity of Fusarium oxysporum f.sp. cubense". Canadian Journal of Microbiology 64, n. 5 (maggio 2018): 349–57. http://dx.doi.org/10.1139/cjm-2017-0638.
Testo completoAbstract (sommario):
The ascomycete fungus Fusarium oxysporum f.sp. cubense race 4 (Foc TR4) causes vascular wilt diseases in banana (Musa spp.). In the present study, the role of SGE1 in regulating growth, conidiation, and pathogenicity of Foc TR4 was investigated. Deletion of SGE1 did not influence vegetative growth but impaired the conidiation of Foc TR4. Besides, the SGE1 deletion mutant basically lost pathogenicity on banana plantlets. Observation under the microscope indicated that the penetration and colonization processes were severely impaired in the SGE1 deletion mutant. Proteomics analysis suggested that SGE1 regulated the production of a series of proteins of Foc TR4. Taken together, our results suggest that SGE1 plays an important role in regulating conidiation and pathogenicity in fungal pathogen Foc TR4.
31
Mooney, J. L., D. E. Hassett e L. N. Yager. "Genetic analysis of suppressors of the veA1 mutation in Aspergillus nidulans." Genetics 126, n. 4 (1 dicembre 1990): 869–74. http://dx.doi.org/10.1093/genetics/126.4.869.
Testo completoAbstract (sommario):
Abstract Light-dependent conidiation in the filamentous ascomycete, Aspergillus nidulans, is contingent on the allelic state of the velvet (veA) gene. Light dependence is abolished by a mutation in this gene (veA1), which allows conidiation to occur in the absence of light. We have isolated and characterized six extragenic suppressors of veA1 that restore the light-dependent conidiation phenotype. Alleles of four genes, defined by complementation tests, were subjected to extensive genetic and phenotypic analysis. The results of light-dark shifting experiments and the phenotypes of double mutant combinations are consistent with the possibility that the expression of the light-dependent phenotype is regulated by specific interactions of the suppressor gene products with the velvet gene product and with each other.
32
Iida, Y., T. Kurata, Y. Harimoto e T. Tsuge. "Nitrite Reductase Gene Upregulated During Conidiation Is Involved in Macroconidium Formation in Fusarium oxysporum". Phytopathology® 98, n. 10 (ottobre 2008): 1099–106. http://dx.doi.org/10.1094/phyto-98-10-1099.
Testo completoAbstract (sommario):
Fusarium oxysporum produces three kinds of asexual spores, microconidia, macroconidia, and chlamydospores. We previously found that the transcript level of the nitrite reductase gene of F. oxysporum, named FoNIIA, was markedly upregulated during conidiation compared with during vegetative growth. FoNIIA was also found to be positively regulated by Ren1 that is a transcription regulator controlling development of microconidia and macroconidia. In this study, we analyzed the function of FoNIIA in conidiation of F. oxysporum. Conidiation cultures showed markedly higher level of accumulation of FoNiiA protein as well as FoNIIA mRNA than vegetative growth cultures. FoNIIA protein was significantly decreased in cultures of the REN1 disruption mutant compared with that of the wild type. These results confirmed that FoNIIA expression is upregulated during conidiation and is positively regulated by REN1. The FoNIIA disruption mutants produced microconidia, macroconidia, and chlamydospores, which were morphologically indistinguishable from those of the wild type. The mutants, however, produced significantly fewer macroconidia than the wild type, although the wild type and mutant strains produced similar numbers of microconidia and chlamydospores. These results demonstrate that nitrite reductase is involved in quantitative control of macroconidium formation as well as nitrate utilization in F. oxysporum.
33
Nižnanský, Ľuboš, Ľudovít Varečka e Svetlana Kryštofová. "Disruption of GABA shunt affects Trichoderma atroviride response to nutritional and environmental stimuli". Acta Chimica Slovaca 9, n. 2 (1 ottobre 2016): 109–13. http://dx.doi.org/10.1515/acs-2016-0019.
Testo completoAbstract (sommario):
Abstract The fungus Trichoderma atroviride is a member of the genus Trichoderma to which belong many species known for high cellulase production, formation of various antibiotics, plant biocontrol and antagonistic activities against other fungi. Deletion of T. atroviride glutamate decarboxylase gene gad caused minor defects in germination, hyphal branching, slower growth and disruption of conidiation pattern. GABA can be used by fungi as a secondary carbon source and as a primary nitrogen source. We analyzed the effect of different nutrient compositions and environmental conditions (light and temperature) on growth and development of T. atroviride in strains defective in the functional GAD. The gad mutants grown on NH4NO3 as a sole carbon source grew slower and formed conidiation bands closer to each other which was clearly demonstrated during their cultivation in race tubes. The gad mutants exhibited slightly lower apical extension growth rate at the room temperature but their apical extension rate dropped significantly at 30 °C. Higher temperature had also inhibitory effect on gad mutant conidiation, whereas 30 °C seems optimal temperature for the parental strain. The optimal temperature for gad mutant conidiation was lower than in F534, about 25 °C.
34
Onai, Kiyoshi, e Hideaki Nakashima. "Mutation of the cys-9 Gene, Which Encodes Thioredoxin Reductase, Affects the Circadian Conidiation Rhythm in Neurospora crassa". Genetics 146, n. 1 (1 maggio 1997): 101–10. http://dx.doi.org/10.1093/genetics/146.1.101.
Testo completoAbstract (sommario):
Ten cysteine auxotrophs of Neurospora crassa were examined with regard to the period lengths of their circadian conidiation rhythms. One of the these cysteine auxotrophs, cys-9, showed dramatic changes in the circadian conidiation rhythm. At 10 μm methionine, the cys-9 mutant had a period length that was 5 hr shorter than that of the wild-type strain during the first 3 days after transfer to continuous darkness. At this concentration of methionine, the period length was unstable after the fourth day and varied widely from 11 to 31 hr. In contrast, other cysteine auxotrophs did not show such instability of the period length at any of the concentrations of methionine tested. Furthermore, only the cys-9 mutant exhibited partial loss of the capacity for temperature compensation of the period length. With regard to cold-induced phase-shifting of the circadian conidiation rhythm, the cys-9 mutant was more sensitive than the wild-type strain to low temperature. The cys-9 + gene was cloned and was found to encode NADPH-dependent thioredoxin reductase. These results indicate that mutation of the gene for thioredoxin reductase results in abnormal expression of the circadian conidiation rhythm in N. crassa.
35
Thompson, Seona, Nirvana J. Croft, Antonis Sotiriou, Hugh D. Piggins e Susan K. Crosthwaite. "Neurospora crassa heat shock factor 1 Is an Essential Gene; a Second Heat Shock Factor-Like Gene, hsf2, Is Required for Asexual Spore Formation". Eukaryotic Cell 7, n. 9 (27 giugno 2008): 1573–81. http://dx.doi.org/10.1128/ec.00427-07.
Testo completoAbstract (sommario):
ABSTRACT Appropriate responses of organisms to heat stress are essential for their survival. In eukaryotes, adaptation to high temperatures is mediated by heat shock transcription factors (HSFs). HSFs regulate the expression of heat shock proteins, which function as molecular chaperones assisting in protein folding and stability. In many model organisms a great deal is known about the products of hsf genes. An important exception is the filamentous fungus and model eukaryote Neurospora crassa. Here we show that two Neurospora crassa genes whose protein products share similarity to known HSFs play different biological roles. We report that heat shock factor 1 (hsf1) is an essential gene and that hsf2 is required for asexual development. Conidiation may be blocked in the hsf2 knockout (hsf2 KO ) strain because HSF2 is an integral element of the conidiation pathway or because it affects the availability of protein chaperones. We report that genes expressed during conidiation, for example fluffy, conidiation-10, and repressor of conidiation-1 show wild-type levels of expression in a hsf2 KO strain. However, consistent with the lack of macroconidium development, levels of eas are much reduced. Cultures of the hsf2 KO strain along with two other aconidial strains, the fluffy and aconidial-2 strains, took longer than the wild type to recover from heat shock. Altered expression profiles of hsp90 and a putative hsp90-associated protein in the hsf2 KO strain after exposure to heat shock may in part account for its reduced ability to cope with heat stress.
36
Bacon, Charles W., e Dorothy M. Hinton. "Microcyclic Conidiation Cycles in Epichloe typhina". Mycologia 83, n. 6 (novembre 1991): 743. http://dx.doi.org/10.2307/3760431.
Testo completo
37
Lapaire, Carrie L., e Larry D. Dunkle. "Microcycle Conidiation in Cercospora zeae-maydis". Phytopathology® 93, n. 2 (febbraio 2003): 193–99. http://dx.doi.org/10.1094/phyto.2003.93.2.193.
Testo completoAbstract (sommario):
Conidia of Cercospora zeae-maydis are the primary inoculum causing gray leaf spot of maize. On nutrient-deficient substrates, but not on water on the leaf surface, conidia germinate and develop secondary conidia on conidiophores produced from germ tubes or conidial cells. A population of conidia increases its numbers more than twofold by 2 days on the surface of a water droplet and by fourfold on trichomes. This microcycle conidiation is suppressed by hydrogen peroxide and ammonium compounds but not by nitrate compounds, amino acids, or simple sugars. Microcycle conidiation is sensitive to α-amanitin and cycloheximide, suggesting that new RNA and proteins must be synthesized. Upon transfer from a humid to a dry atmosphere, secondary conidia and conidiophores dehydrate and collapse. Mature, dehydrated, secondary conidia are liberated by wind speeds approximately one-third those required to liberate hydrated conidia. The dispersed secondary conidia can rehydrate and germinate normally. Because this microcycle conidiation occurs at the expense of endogenous reserves, the ability to produce secondary conidia is lost after four successive cycles without a period of growth on nutrient media. This alternative method of maintaining inoculum potential during periods of fluctuating relative humidity may have epidemiological consequences when primary conidia fail to infect.
38
Bacon, Charles W., e Dorothy M. Hinton. "Microcyclic Conidiation Cycles in Epichloe Typhina". Mycologia 83, n. 6 (novembre 1991): 743–51. http://dx.doi.org/10.1080/00275514.1991.12026079.
Testo completo
39
Nakashima, Hideaki, e Kiyoshi Onai. "The circadian conidiation rhythm inNeurospora crassa". Seminars in Cell & Developmental Biology 7, n. 6 (dicembre 1996): 765–74. http://dx.doi.org/10.1006/scdb.1996.0094.
Testo completo
40
Wakefield, Laura, David M. Gadoury, Robert C. Seem, Michael G. Milgroom, Qi Sun e Lance Cadle-Davidson. "Differential Gene Expression During Conidiation in the Grape Powdery Mildew Pathogen, Erysiphe necator". Phytopathology® 101, n. 7 (luglio 2011): 839–46. http://dx.doi.org/10.1094/phyto-11-10-0295.
Testo completoAbstract (sommario):
Asexual sporulation (conidiation) is coordinately regulated in the grape powdery mildew pathogen Erysiphe necator but nothing is known about its genetic regulation. We hypothesized that genes required for conidiation in other fungi would be upregulated at conidiophore initiation or full conidiation (relative to preconidiation vegetative growth and development of mature ascocarps), and that the obligate biotrophic lifestyle of E. necator would necessitate some novel gene regulation. cDNA amplified fragment length polymorphism analysis with 45 selective primer combinations produced ≈1,600 transcript-derived fragments (TDFs), of which 620 (39%) showed differential expression. TDF sequences were annotated using BLAST analysis of GenBank and of a reference transcriptome for E. necator developed by 454-FLX pyrosequencing of a normalized cDNA library. One-fourth of the differentially expressed, annotated sequences had similarity to fungal genes of unknown function. The remaining genes had annotated function in metabolism, signaling, transcription, transport, and protein fate. As expected, a portion of orthologs known in other fungi to be involved in developmental regulation was upregulated immediately prior to or during conidiation; particularly noteworthy were several genes associated with the light-dependent VeA regulatory system, G-protein signaling (Pth11 and a kelch repeat), and nuclear transport (importin-β and Ran). This work represents the first investigation into differential gene expression during morphogenesis in E. necator and identifies candidate genes and hypotheses for characterization in powdery mildews. Our results indicate that, although control of conidiation in powdery mildews may share some basic elements with established systems, there are significant points of divergence as well, perhaps due, in part, to the obligate biotrophic lifestyle of powdery mildews.
41
Tong, Sen-Miao, Ding-Yi Wang, Qing Cai, Sheng-Hua Ying e Ming-Guang Feng. "Opposite Nuclear Dynamics of Two FRH-Dominated Frequency Proteins Orchestrate Non-Rhythmic Conidiation in Beauveria bassiana". Cells 9, n. 3 (5 marzo 2020): 626. http://dx.doi.org/10.3390/cells9030626.
Testo completoAbstract (sommario):
Non-rhythmic conidiation favors large-scale production of conidia serving as active ingredients of fungal insecticides, but its regulatory mechanism is unknown. Here, we report that two FREQUENCY (FRQ) proteins (Frq1/2) governed by a unique FRQ-interacting RNA helicase (FRH) orchestrate this valuable trait in Beauveria bassiana, an asexual insect-pathogenic fungus. Frq1 (964 aa) and Frq2 (583 aa) exhibited opposite expression dynamics (rhythms) in nucleus and steadily high expression levels in cytoplasm under light or in darkness no matter whether one of them was present or absent. Such opposite nuclear dynamics presented a total FRQ (pooled Frq1/2) level sufficient to persistently activate central developmental pathway in daytime and nighttime and supports continuous (non-rhythmic) conidiation for rapid maximization of conidial production in a fashion independent of photoperiod change. Importantly, both nuclear dynamics and cytoplasmic stability of Frq1 and Frq2 were abolished in the absence of the FRH-coding gene nonessential for the fungal viability, highlighting an indispensability of FRH for the behaviors of Frq1 and Frq2 in both nucleus and cytoplasm. These findings uncover a novel circadian system more complicated than the well-known Neurospora model that controls rhythmic conidiation, and provide a novel insight into molecular control of non-rhythmic conidiation in B. bassiana.
42
Šimkovič, Martin, Peter Ditte, Anita Kurucová, Boris Lakatoš e L’udovít Varečka. "Ca2+-dependent induction of conidiation in submerged cultures of Trichoderma viride". Canadian Journal of Microbiology 54, n. 4 (aprile 2008): 291–98. http://dx.doi.org/10.1139/w08-001.
Testo completoAbstract (sommario):
The presence of Ca2+ (up to 0.1 mol/L) in the cultivation media was found to induce the formation of conidia in submerged mycelia of Trichoderma viride in a concentration-dependent manner. Ca2+ dramatically stimulated conidiation after 70 h of cultivation. The effect was present in the dark, and illumination stimulated it only marginally. Low (less than 100 μmol/L) Ca2+ concentrations induced the formation of chlamydospores. Sr2+ could substitute Ca2+ in conidiogenesis with lower efficiency (almost 2 orders of magnitude), while the efficiency of Mg2+, Mn2+, or Ba2+ was lower by almost 3 orders of magnitude. Our results demonstrate that mycelial Ca2+ homeostasis has powerful effects on the conidiation and mycelial morphogenesis in T. viride, and they suggest that there is an additional mechanism of conidiation in addition to those induced by light and starvation.
43
Jørgensen, Thomas R., Kristian F. Nielsen, Mark Arentshorst, JooHae Park, Cees A. van den Hondel, Jens C. Frisvad e Arthur F. Ram. "Submerged Conidiation and Product Formation by Aspergillus niger at Low Specific Growth Rates Are Affected in Aerial Developmental Mutants". Applied and Environmental Microbiology 77, n. 15 (7 giugno 2011): 5270–77. http://dx.doi.org/10.1128/aem.00118-11.
Testo completoAbstract (sommario):
ABSTRACTExposure to an aerial environment or severe nutrient limitation induces asexual differentiation in filamentous fungi. Submerged cultivation ofAspergillus nigerin carbon- and energy-limited retentostat cultures both induces and fuels conidiation. Physiological and transcriptomic analyses have revealed that this differentiation strongly affects product formation. Since conidiation is inherent in the aerial environment, we hypothesized that product formation near zero growth can be influenced by affecting differentiation or development of aerial hyphae in general. To investigate this idea, three developmental mutants (ΔfwnA,scl-1, andscl-2mutants) that have no apparent vegetative growth defects were cultured in maltose-limited retentostat cultures. The secondary-metabolite profile of the wild-type strain defined flavasperone, aurasperone B, tensidol B, and two so far uncharacterized compounds as associated with conidium formation, while fumonisins B2, B4, and B6were characteristic of early response to nutrient limitation by the vegetative mycelium. The developmental mutants responded differently to the severe substrate limitation, which resulted in distinct profiles of growth and product formation.fwnAencodes the polyketide synthase responsible for melanin biosynthesis during aerial differentiation, and we show that conidial melanin synthesis in submerged retentostat cultures and aurasperone B production arefwnAdependent. Thescl-1andscl-2strains are two UV mutants generated in the ΔfwnAbackground that displayed reduced asexual conidiation and formed sclerotium-like structures on agar plates. The reduced conidiation phenotypes of thescl-1andscl-2strains are reflected in the retentostat cultivation and are accompanied by elimination or severely reduced accumulation of secondary metabolites and distinctly enhanced accumulation of extracellular protein. This investigation shows that submerged conidiation and product formation of a mitosporic fungus cultured at low specific growth rates can be fundamentally affected by interfering with the genetic program for differentiation of aerial hyphae, opening new perspectives for tailoring industrial performance.
44
Kwon, Nak-Jung, Hee-Soo Park, Seunho Jung, Sun Chang Kim e Jae-Hyuk Yu. "The Putative Guanine Nucleotide Exchange Factor RicA Mediates Upstream Signaling for Growth and Development in Aspergillus". Eukaryotic Cell 11, n. 11 (21 settembre 2012): 1399–412. http://dx.doi.org/10.1128/ec.00255-12.
Testo completoAbstract (sommario):
ABSTRACTHeterotrimeric G proteins (G proteins) govern growth, development, and secondary metabolism in various fungi. Here, we characterizedricA, which encodes a putative GDP/GTP exchange factor for G proteins in the model fungusAspergillus nidulansand the opportunistic human pathogenAspergillus fumigatus. In both species,ricAmRNA accumulates during vegetative growth and early developmental phases, but it is not present in spores. The deletion ofricAresults in severely impaired colony growth and the total (forA. nidulans) or near (forA. fumigatus) absence of asexual sporulation (conidiation). The overexpression (OE) of theA. fumigatus ricAgene (AfricA) restores growth and conidiation in the ΔAnricAmutant to some extent, indicating partial conservation of RicA function inAspergillus. A series of double mutant analyses revealed that the removal of RgsA (an RGS protein of the GanB Gα subunit), but notsfgA,flbA,rgsB, orrgsC, restored vegetative growth and conidiation in ΔAnricA. Furthermore, we found that RicA can physically interact with GanB in yeast andin vitro. Moreover, the presence of two copies or OE ofpkaAsuppresses the profound defects caused by ΔAnricA, indicating that RicA-mediated growth and developmental signaling is primarily through GanB and PkaA inA. nidulans. Despite the lack of conidiation,brlAandvosAmRNAs accumulated to normal levels in the ΔricAmutant. In addition, mutants overexpressingfluGorbrlA(OEfluGor OEbrlA) failed to restore development in the ΔAnricAmutant. These findings suggest that the commencement of asexual development requires unknown RicA-mediated signaling input inA. nidulans.
45
Roberts, A. N., V. Berlin, K. M. Hager e C. Yanofsky. "Molecular analysis of a Neurospora crassa gene expressed during conidiation." Molecular and Cellular Biology 8, n. 6 (giugno 1988): 2411–18. http://dx.doi.org/10.1128/mcb.8.6.2411.
Testo completoAbstract (sommario):
The asexual developmental pathway in the life cycle of the filamentous fungus Neurospora crassa culminates in the formation of spores called conidia. Several clones of genomic Neurospora DNA have been isolated that correspond to mRNA species expressed during conidiation and not during mycelial growth (V. Berlin and C. Yanofsky, Mol. Cell. Biol. 5:849-855, 1985). In this paper we describe the characterization of one of these clones, named pCon-10a. This clone contains two genes, con-10 and con-13, which are induced coordinately during the later stages of conidiation. The two genes are separated by 1.4 kilobases of DNA; they are located on linkage group IV and are transcribed from the same strand of DNA. The molecular organization and sequence of one of these genes, con-10, and its flanking regions are presented. Full-length cDNA clones for con-10 also were isolated and sequenced, and transcription-initiation and polyadenylation sites were defined. The con-10 gene contains an open reading frame interrupted by two small introns and encodes an 86-amino-acid residue polypeptide that is both hydrophilic and weakly acidic. Expression of the con-10 gene in various mutants defective at different stages of conidiation indicates that it plays a role after aerial hyphal development. Possible functions, organization, and regulation of conidiation-specific genes are discussed.
46
Takano, Yoshitaka, Kenichi Komeda, Kaihei Kojima e Tetsuro Okuno. "Proper Regulation of Cyclic AMP-Dependent Protein Kinase Is Required for Growth, Conidiation, and Appressorium Function in the Anthracnose Fungus Colletotrichum lagenarium". Molecular Plant-Microbe Interactions® 14, n. 10 (ottobre 2001): 1149–57. http://dx.doi.org/10.1094/mpmi.2001.14.10.1149.
Testo completoAbstract (sommario):
Colletotrichum lagenarium, the casual agent of anthracnose of cucumber, forms specialized infection structures, called appressoria, during infection. To evaluate the role of cAMP signaling in C. lagenarium, we isolated and functionally characterized the regulatory subunit gene of the cAMP-dependent protein kinase (PKA). The RPK1 gene encoding the PKA regulatory subunit was isolated from C. lagenarium by polymerase chain reaction-based screening. rpk1 mutants, generated by gene replacement, exhibited high PKA activity during vegetative growth, whereas the wild-type strain had basal level activity. The rpk1 mutants showed significant reduction in vegetative growth and conidiation. Furthermore, the rpk1 mutants were nonpathogenic on cucumber plants, whereas they formed lesions when inoculated through wounds. A suppressor mutant showing restored growth and conidiation was isolated from a rpk1 mutant culture. The rpk1-suppressor mutant did not show high PKA activity, unlike the parental rpk1 mutant, suggesting that high PKA activity inhibits normal growth and conidiation. The suppressor mutant, however, was nonpathogenic on cucumber and failed to form lesions, even when inoculated through wounds. The rpk1 and suppressor mutants formed melanized appressoria on the host leaf surface but were unable to generate penetration hyphae. These results suggest that proper regulation of the PKA activity by the RPK1-encoded regulatory subunit is required for growth, conidiation, and appressorium function in C. lagenarium.
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Waller, Timothy J., Jennifer Vaiciunas, Christine Constantelos e Peter V. Oudemans. "Evidence that Blueberry Floral Extracts Influence Secondary Conidiation and Appressorial Formation of Colletotrichum fioriniae". Phytopathology® 108, n. 5 (maggio 2018): 561–67. http://dx.doi.org/10.1094/phyto-07-17-0263-r.
Testo completoAbstract (sommario):
Blueberry anthracnose, caused by Colletotrichum fioriniae, is a pre- and postharvest disease of cultivated highbush blueberry (Vaccinium corymbosum). During disease development, the pathogen undergoes several lifestyle changes during host colonization, including epiphytic, quiescent, and necrotrophic phases. It is not clear, however, what if any host signals alter the pattern of colonization during the initial epiphytic phase and infection. This research investigated the role of blueberry floral extracts (FE) on fungal development. Results show that FE significantly increased both the quantity and rate of secondary conidiation and appressorial formation in vitro, suggesting that floral components could decrease the minimum time required for infection. Activity of FE was readily detected in water collected from field samples, where secondary conidiation and appressorial formation decreased as rainwater collections were further removed from flowers. A comparison of FE from four blueberry cultivars with different levels of field susceptibility revealed that appressorial formation but not secondary conidiation significantly increased with the FE from susceptible cultivars versus resistant cultivars. Inoculum supplemented with FE produced higher levels of disease on ripe blueberry fruit as compared with inoculum with water only. Flowers from other ericaceous species were found to also induce secondary conidiation and appressorial formation of C. fioriniae. This research provides strong evidence that flowers can contribute substantially to the infection process of C. fioriniae, signifying the importance of the bloom period for developing effective disease management strategies.
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Roberts, A. N., V. Berlin, K. M. Hager e C. Yanofsky. "Molecular analysis of a Neurospora crassa gene expressed during conidiation". Molecular and Cellular Biology 8, n. 6 (giugno 1988): 2411–18. http://dx.doi.org/10.1128/mcb.8.6.2411-2418.1988.
Testo completoAbstract (sommario):
The asexual developmental pathway in the life cycle of the filamentous fungus Neurospora crassa culminates in the formation of spores called conidia. Several clones of genomic Neurospora DNA have been isolated that correspond to mRNA species expressed during conidiation and not during mycelial growth (V. Berlin and C. Yanofsky, Mol. Cell. Biol. 5:849-855, 1985). In this paper we describe the characterization of one of these clones, named pCon-10a. This clone contains two genes, con-10 and con-13, which are induced coordinately during the later stages of conidiation. The two genes are separated by 1.4 kilobases of DNA; they are located on linkage group IV and are transcribed from the same strand of DNA. The molecular organization and sequence of one of these genes, con-10, and its flanking regions are presented. Full-length cDNA clones for con-10 also were isolated and sequenced, and transcription-initiation and polyadenylation sites were defined. The con-10 gene contains an open reading frame interrupted by two small introns and encodes an 86-amino-acid residue polypeptide that is both hydrophilic and weakly acidic. Expression of the con-10 gene in various mutants defective at different stages of conidiation indicates that it plays a role after aerial hyphal development. Possible functions, organization, and regulation of conidiation-specific genes are discussed.
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Etxebeste, Oier, Min Ni, Aitor Garzia, Nak-Jung Kwon, Reinhard Fischer, Jae-Hyuk Yu, Eduardo A. Espeso e Unai Ugalde. "Basic-Zipper-Type Transcription Factor FlbB Controls Asexual Development in Aspergillus nidulans". Eukaryotic Cell 7, n. 1 (9 novembre 2007): 38–48. http://dx.doi.org/10.1128/ec.00207-07.
Testo completoAbstract (sommario):
ABSTRACT The fungal colony is a complex multicellular unit consisting of various cell types and functions. Asexual spore formation (conidiation) is integrated through sensory and regulatory elements into the general morphogenetic plan, in which the activation of the transcription factor BrlA is the first determining step. A number of early regulatory elements acting upstream of BrlA (fluG and flbA-E) have been identified, but their functional relations remain to be further investigated. In this report we describe FlbB as a putative basic-zipper-type transcription factor restricted to filamentous fungi. FlbB accumulates at the hyphal apex during early vegetative growth but is later found in apical nuclei, suggesting that an activating modification triggers nuclear import. Moreover, proper temporal and quantitative expression of FlbB is a prerequisite for brlA transcription, and misscheduled overexpression inhibits conidiation. We also present evidence that FlbB activation results in the production of a second diffusible signal, acting downstream from the FluG factor, to induce conidiation.
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Shrode, Lori Bailey, Zachary A. Lewis, Lori D. White, Deborah Bell-Pedersen e Daniel J. Ebbole. "vvd Is Required for Light Adaptation of Conidiation-Specific Genes of Neurospora crassa, but Not Circadian Conidiation". Fungal Genetics and Biology 32, n. 3 (aprile 2001): 169–81. http://dx.doi.org/10.1006/fgbi.2001.1264.
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