scholarly journals Transcriptional Changes in the Transition from Vegetative Cells to Asexual Development in the Model Fungus Aspergillus nidulans

2012 ◽  
Vol 12 (2) ◽  
pp. 311-321 ◽  
Author(s):  
Aitor Garzia ◽  
Oier Etxebeste ◽  
Julio Rodríguez-Romero ◽  
Reinhard Fischer ◽  
Eduardo A. Espeso ◽  
...  
Keyword(s):  
Gene Expression ◽  
Aspergillus Nidulans ◽  
Cell Types ◽  
Asexual Development ◽  
Primary Metabolism ◽  
Air Exposure ◽  
Vegetative Cells ◽  
Content Type ◽  
Zinc Cluster ◽  
Transcriptional Changes

ABSTRACTMorphogenesis encompasses programmed changes in gene expression that lead to the development of specialized cell types. In the model fungusAspergillus nidulans, asexual development involves the formation of characteristic cell types, collectively known as the conidiophore. With the aim of determining the transcriptional changes that occur upon induction of asexual development, we have applied massive mRNA sequencing to compare the expression pattern of 19-h-old submerged vegetative cells (hyphae) with that of similar hyphae after exposure to the air for 5 h. We found that the expression of 2,222 (20.3%) of the predicted 10,943A. nidulanstranscripts was significantly modified after air exposure, 2,035 being downregulated and 187 upregulated. The activation during this transition of genes that belong specifically to the asexual developmental pathway was confirmed. Another remarkable quantitative change occurred in the expression of genes involved in carbon or nitrogen primary metabolism. Genes participating in polar growth or sexual development were transcriptionally repressed, as were those belonging to the HogA/SakA stress response mitogen-activated protein (MAP) kinase pathway. We also identified significant expression changes in several genes purportedly involved in redox balance, transmembrane transport, secondary metabolite production, or transcriptional regulation, mainly binuclear-zinc cluster transcription factors. Genes coding for these four activities were usually grouped in metabolic clusters, which may bring regulatory implications for the induction of asexual development. These results provide a blueprint for further stage-specific gene expression studies during conidiophore development.

scholarly journals Aspergillus nidulans wetA activates spore-specific gene expression.

1991 ◽  
Vol 11 (1) ◽  
pp. 55-62 ◽  
Author(s):  
M A Marshall ◽  
W E Timberlake
Keyword(s):  
Gene Expression ◽  
Cell Wall ◽  
Aspergillus Nidulans ◽  
Gene Activation ◽  
Regulatory Function ◽  
Specific Gene ◽  
Coding Region ◽  
Vegetative Cells ◽  
Mutant Strains ◽  
Late Stages

The Aspergillus nidulans wetA gene is required for synthesis of cell wall layers that make asexual spores (conidia) impermeable. In wetA mutant strains, conidia take up water and autolyze rather than undergoing the final stages of maturation. wetA is activated during conidiogenesis by sequential expression of the brlA and abaA regulatory genes. To determine whether wetA regulates expression of other sporulation-specific genes, its coding region was fused to a nutritionally regulated promoter that permits gene activation in vegetative cells (hyphae) under conditions that suppress conidiation. Expression of wetA in hyphae inhibited growth and caused excessive branching. It did not lead to activation of brlA or abaA but did cause accumulation of transcripts from genes that are normally expressed specifically during the late stages of conidiation and whose mRNAs are stored in mature spores. Thus, wetA directly or indirectly regulates expression of some spore-specific genes. At least one gene (wA), whose mRNA does not occur in spores but rather accumulates in the sporogenous phialide cells, was activated by wetA, suggesting that wetA may have a regulatory function in these cells as well as in spores. We propose that wetA is responsible for activating a set of genes whose products make up the final two conidial wall layers or direct their assembly and through this activity is responsible for acquisition of spore dormancy.

scholarly journals Transcriptomic, Protein-DNA Interaction, and Metabolomic Studies of VosA, VelB, and WetA in Aspergillus nidulans Asexual Spores

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ming-Yueh Wu ◽  
Matthew E. Mead ◽  
Mi-Kyung Lee ◽  
George F. Neuhaus ◽  
Donovon A. Adpressa ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Secondary Metabolism ◽  
Aspergillus Nidulans ◽  
Filamentous Fungi ◽  
Genetic Regulatory Networks ◽  
Asexual Development ◽  
Morphological Development ◽  
Vast Number ◽  
Content Type ◽  
Metabolic Remodeling

ABSTRACT In filamentous fungi, asexual development involves cellular differentiation and metabolic remodeling leading to the formation of intact asexual spores. The development of asexual spores (conidia) in Aspergillus is precisely coordinated by multiple transcription factors (TFs), including VosA, VelB, and WetA. Notably, these three TFs are essential for the structural and metabolic integrity, i.e., proper maturation, of conidia in the model fungus Aspergillus nidulans. To gain mechanistic insight into the complex regulatory and interdependent roles of these TFs in asexual sporogenesis, we carried out multi-omics studies on the transcriptome, protein-DNA interactions, and primary and secondary metabolism employing A. nidulans conidia. RNA sequencing and chromatin immunoprecipitation sequencing analyses have revealed that the three TFs directly or indirectly regulate the expression of genes associated with heterotrimeric G-protein signal transduction, mitogen-activated protein (MAP) kinases, spore wall formation and structural integrity, asexual development, and primary/secondary metabolism. In addition, metabolomics analyses of wild-type and individual mutant conidia indicate that these three TFs regulate a diverse array of primary metabolites, including those in the tricarboxylic acid (TCA) cycle, certain amino acids, and trehalose, and secondary metabolites such as sterigmatocystin, emericellamide, austinol, and dehydroaustinol. In summary, WetA, VosA, and VelB play interdependent, overlapping, and distinct roles in governing morphological development and primary/secondary metabolic remodeling in Aspergillus conidia, leading to the production of vital conidia suitable for fungal proliferation and dissemination. IMPORTANCE Filamentous fungi produce a vast number of asexual spores that act as efficient propagules. Due to their infectious and/or allergenic nature, fungal spores affect our daily life. Aspergillus species produce asexual spores called conidia; their formation involves morphological development and metabolic changes, and the associated regulatory systems are coordinated by multiple transcription factors (TFs). To understand the underlying global regulatory programs and cellular outcomes associated with conidium formation, genomic and metabolomic analyses were performed in the model fungus Aspergillus nidulans. Our results show that the fungus-specific WetA/VosA/VelB TFs govern the coordination of morphological and chemical developments during sporogenesis. The results of this study provide insights into the interdependent, overlapping, or distinct genetic regulatory networks necessary to produce intact asexual spores. The findings are relevant for other Aspergillus species such as the major human pathogen Aspergillus fumigatus and the aflatoxin producer Aspergillus flavus.

scholarly journals How the Anaerobic Enteropathogen Clostridioides difficile Tolerates Low O2 Tensions

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Nicolas Kint ◽  
Carolina Alves Feliciano ◽  
Maria C. Martins ◽  
Claire Morvan ◽  
Susana F. Fernandes ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Anaerobic Bacteria ◽  
Growth Defect ◽  
Strictly Anaerobic ◽  
Low Oxygen ◽  
Air Exposure ◽  
Vegetative Cells ◽  
Content Type ◽  
Clostridioides Difficile

ABSTRACT Clostridioides difficile is a major cause of diarrhea associated with antibiotherapy. After germination of C. difficile spores in the small intestine, vegetative cells are exposed to low oxygen (O2) tensions. While considered strictly anaerobic, C. difficile is able to grow in nonstrict anaerobic conditions (1 to 3% O2) and tolerates brief air exposure indicating that this bacterium harbors an arsenal of proteins involved in O2 detoxification and/or protection. Tolerance of C. difficile to low O2 tensions requires the presence of the alternative sigma factor, σB, involved in the general stress response. Among the genes positively controlled by σB, four encode proteins likely involved in O2 detoxification: two flavodiiron proteins (FdpA and FdpF) and two reverse rubrerythrins (revRbr1 and revRbr2). As previously observed for FdpF, we showed that both purified revRbr1 and revRbr2 harbor NADH-linked O2- and H2O2-reductase activities in vitro, while purified FdpA mainly acts as an O2-reductase. The growth of a fdpA mutant is affected at 0.4% O2, while inactivation of both revRbrs leads to a growth defect above 0.1% O2. O2-reductase activities of these different proteins are additive since the quadruple mutant displays a stronger phenotype when exposed to low O2 tensions compared to the triple mutants. Our results demonstrate a key role for revRbrs, FdpF, and FdpA proteins in the ability of C. difficile to grow in the presence of physiological O2 tensions such as those encountered in the colon. IMPORTANCE Although the gastrointestinal tract is regarded as mainly anoxic, low O2 tension is present in the gut and tends to increase following antibiotic-induced disruption of the host microbiota. Two decreasing O2 gradients are observed, a longitudinal one from the small to the large intestine and a second one from the intestinal epithelium toward the colon lumen. Thus, O2 concentration fluctuations within the gastrointestinal tract are a challenge for anaerobic bacteria such as C. difficile. This enteropathogen has developed efficient strategies to detoxify O2. In this work, we identified reverse rubrerythrins and flavodiiron proteins as key actors for O2 tolerance in C. difficile. These enzymes are responsible for the reduction of O2 protecting C. difficile vegetative cells from associated damages. Original and complex detoxification pathways involving O2-reductases are crucial in the ability of C. difficile to tolerate O2 and survive to O2 concentrations encountered in the gastrointestinal tract.

scholarly journals Genomewide Expression Profile Analysis of the Candida glabrata Pdr1 Regulon

2010 ◽  
Vol 10 (3) ◽  
pp. 373-383 ◽  
Author(s):  
Kelly E. Caudle ◽  
Katherine S. Barker ◽  
Nathan P. Wiederhold ◽  
Lijing Xu ◽  
Ramin Homayouni ◽  
...  
Keyword(s):  
Gene Expression ◽  
Differentially Expressed Genes ◽  
Candida Glabrata ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Differentially Expressed ◽  
Resistant Isolate ◽  
Content Type ◽  
Activating Mutations ◽  
Zinc Cluster

ABSTRACTThe ABC transportersCandida glabrataCdr1 (CgCdr1), CgPdh1, and CgSnq2 are known to mediate azole resistance in the pathogenic fungusC. glabrata. Activating mutations inCgPDR1, a zinc cluster transcription factor, result in constitutive upregulation of these ABC transporter genes but to various degrees. We examined the genomewide gene expression profiles of two matched azole-susceptible and -resistantC. glabrataclinical isolate pairs. Of the differentially expressed genes identified in the gene expression profiles for these two matched pairs, there were 28 genes commonly upregulated withCgCDR1in both isolate sets includingYOR1,LCB5,RTA1,POG1,HFD1, and several members of theFLOgene family of flocculation genes. We then sequencedCgPDR1from each susceptible and resistant isolate and found two novel activating mutations that conferred increased resistance when they were expressed in a common background strain in whichCgPDR1had been disrupted. Microarray analysis comparing these reengineered strains to their respective parent strains identified a set of commonly differentially expressed genes, includingCgCDR1,YOR1, andYIM1, as well as genes uniquely regulated by specific mutations. Our results demonstrate that while CgPdr1 activates a broad repertoire of genes, specific activating mutations result in the activation of discrete subsets of this repertoire.

scholarly journals Gene-expression changes induced by Feline immunodeficiency virus infection differ in epithelial cells and lymphocytes

2005 ◽  
Vol 86 (8) ◽  
pp. 2239-2248 ◽  
Author(s):  
R. J. O. Dowling ◽  
D. Bienzle
Keyword(s):  
Gene Expression ◽  
Epithelial Cells ◽  
Virus Infection ◽  
Feline Immunodeficiency Virus ◽  
Cell Types ◽  
Early Gene ◽  
Time Points ◽  
Subtype B ◽  
Immunodeficiency Virus ◽  
Transcriptional Changes

Infection of cats with Feline immunodeficiency virus (FIV) is an important model for understanding comparative lentivirus biology. In vivo, FIV infects lymphocytes and monocyte/macrophages, but in vitro infection is commonly investigated in epithelial Crandell–Reese Feline Kidney (CRFK) cells. In this study, the transcriptional responses of CRFK cells and primary lymphocytes to infection with FIV 34TF, a cloned subtype A virus, and FIV USgaB01, a biological subtype B isolate, were determined. Reverse-transcribed mRNA from both cell types was hybridized to microarrays containing 1700 human expressed sequence tags in duplicate and data were analysed with Significance Analysis of Microarrays (sam) software. Results from six experiments assessing homeostatic cross-species hybridization excluded 3·48 % inconsistently detected transcripts. Analysis of data from five time points over 48 h after infection identified 132 and 24 differentially expressed genes in epithelial cells and lymphocytes, respectively. Genes involved in protein synthesis, the cell cycle, structure and metabolism were affected. The magnitude of gene-expression changes ranged from 0·62 to 1·62 and early gene induction was followed by downregulation after 4 h. Transcriptional changes in CRFK cells were distinct from those in lymphocytes, except for heat-shock cognate protein 71, which was induced at multiple time points in both cell types. These findings indicate that FIV infection induces transcriptional changes of a modest magnitude in a wide range of genes, which is probably reflective of the relatively non-cytopathic nature of virus infection.

scholarly journals Functional Characterization of a New Member of the Cdk9 Family in Aspergillus nidulans

2010 ◽  
Vol 9 (12) ◽  
pp. 1901-1912 ◽  
Author(s):  
Friederike Bathe ◽  
Claudia Kempf ◽  
Stephen A. Osmani ◽  
Aysha H. Osmani ◽  
Sabrina Hettinger ◽  
...  
Keyword(s):  
Aspergillus Nidulans ◽  
Fluorescent Protein ◽  
Transcription Elongation ◽  
Functional Characterization ◽  
Asexual Development ◽  
Full Spectrum ◽  
Content Type ◽  
Essential Components

ABSTRACT Cdk9-like kinases in complex with T-type cyclins are essential components of the eukaryotic transcription elongation machinery. The full spectrum of Cdk9/cyclin T targets, as well as the specific consequences of phosphorylations, is still largely undefined. We identify and characterize here a Cdk9 kinase (PtkA) in the filamentous ascomycete Aspergillus nidulans. Deletion of ptkA had a lethal effect in later stages of vegetative growth and completely impeded asexual development. Overexpression of ptkA affected directionality of polarized growth and the initiation of new branching sites. A green fluorescent protein-tagged PtkA version localized inside the nucleus during interphase, supporting a role of PtkA in transcription elongation, as observed in other organisms. We also identified a putative cyclin T homolog, PchA, in the A. nidulans genome and confirmed its interaction with PtkA in vivo. Surprisingly, the Pcl-like cyclin PclA, previously described to be involved in asexual development, was also found to interact with PtkA, indicating a possible role of PtkA in linking transcriptional activity with development and/or morphogenesis in A. nidulans. This is the first report of a Cdk9 kinase interacting with a Pcl-like cyclin, revealing interesting new aspects about the involvement of this Cdk-subfamily in differential gene expression.

scholarly journals Cell-specific cis-natural antisense transcripts (cis-NATs) in the sperm and the pollen vegetative cells of Arabidopsis thaliana

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 93
Author(s):  
Peng Qin ◽  
Ann E. Loraine ◽  
Sheila McCormick
Keyword(s):  
Gene Expression ◽  
Vegetative Cell ◽  
Cell Types ◽  
Antisense Transcripts ◽  
Vegetative Cells ◽  
Natural Antisense Transcripts ◽  
Protein Coding ◽  
Regulate Gene Expression ◽  
Genome Wide ◽  
Gene Models

Background: cis-NATs (cis-natural antisense transcripts) are transcribed from opposite strands of adjacent genes and have been shown to regulate gene expression by generating small RNAs from the overlapping region. cis-NATs are important for plant development and resistance to pathogens and stress. Several genome-wide investigations identified a number of cis-NAT pairs, but these investigations predicted cis-NATS using expression data from bulk samples that included lots of cell types. Some cis-NAT pairs identified from those investigations might not be functional, because both transcripts of cis-NAT pairs need to be co-expressed in the same cell. Pollen only contains two cell types, two sperm and one vegetative cell, which makes cell-specific investigation of cis-NATs possible. Methods: We investigated potential protein-coding cis-NATs in pollen and sperm using pollen RNA-seq data and TAIR10 gene models using the Integrated Genome Browser.  We then used sperm microarray data and sRNAs in sperm and pollen to determine possibly functional cis-NATs in the sperm or vegetative cell, respectively. Results: We identified 1471 potential protein-coding cis-NAT pairs, including 131 novel pairs that were not present in TAIR10 gene models. In pollen, 872 possibly functional pairs were identified. 72 and 56 pairs were potentially functional in sperm and vegetative cells, respectively. sRNAs were detected at 794 genes, belonging to 739 pairs. Conclusion: These potential candidates in sperm and the vegetative cell are tools for understanding gene expression mechanisms in pollen.

scholarly journals Genetic Network Architecture and Environmental Cues Drive Spatial Organization of Phenotypic Division of Labor in Streptomyces coelicolor

mBio ◽  
2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Vineetha M. Zacharia ◽  
Yein Ra ◽  
Catherine Sue ◽  
Elizabeth Alcala ◽  
Jewel N. Reaso ◽  
...  
Keyword(s):  
Gene Expression ◽  
Network Architecture ◽  
Spatial Organization ◽  
Streptomyces Coelicolor ◽  
Cell Types ◽  
Antibiotic Biosynthesis ◽  
Developmental Pathway ◽  
Content Type ◽  
Reproductive Structures ◽  
Physiological Gradients

ABSTRACT A number of bacteria are known to differentiate into cells with distinct phenotypic traits during processes such as biofilm formation or the development of reproductive structures. These cell types, by virtue of their specialized functions, embody a division of labor. However, how bacteria build spatial patterns of differentiated cells is not well understood. Here, we examine the factors that drive spatial patterns in divisions of labor in colonies of Streptomyces coelicolor, a multicellular bacterium capable of synthesizing an array of antibiotics and forming complex reproductive structures (e.g., aerial hyphae and spores). Using fluorescent reporters, we demonstrate that the pathways for antibiotic biosynthesis and aerial hypha formation are activated in distinct waves of gene expression that radiate outwards in S. coelicolor colonies. We also show that the spatiotemporal separation of these cell types depends on a key activator in the developmental pathway, AdpA. Importantly, when we manipulated local gradients by growing competing microbes nearby, or through physical disruption, expression in these pathways could be decoupled and/or disordered, respectively. Finally, the normal spatial organization of these cell types was partially restored with the addition of a siderophore, a public good made by these organisms, to the growth medium. Together, these results indicate that spatial divisions of labor in S. coelicolor colonies are determined by a combination of physiological gradients and regulatory network architecture, key factors that also drive patterns of cellular differentiation in multicellular eukaryotic organisms. IMPORTANCE Streptomyces coelicolor is a multicellular bacterium that differentiates into specialized cell types and produces a diverse array of natural products. While much is known about the genetic networks that regulate development and antibiotic biosynthesis in S. coelicolor, what drives the spatial organization of these activities within a colony remains to be explored. By using time-lapse microscopy to monitor gene expression in developmental and antibiotic biosynthesis pathways, we found that expression in these pathways occurs in spatiotemporally separated waves. Normally, expression of the antibiotic biosynthesis pathway preceded expression in the developmental pathway; however, this order was compromised in a mutant lacking a key developmental regulator. Furthermore, when we disrupted the local gradients during S. coelicolor growth, we observed disordered patterns of gene expression within colonies. Together, these results indicate that spatial divisions of labor in S. coelicolor colonies are determined by a combination of regulatory network architecture and physiological gradients.

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