scholarly journals Isolation of a gene required for programmed initiation of development by Aspergillus nidulans.

1992 ◽  
Vol 12 (9) ◽  
pp. 3827-3833 ◽  
Author(s):  
T H Adams ◽  
W A Hide ◽  
L N Yager ◽  
B N Lee
Keyword(s):  
Life Cycle ◽  
Aspergillus Nidulans ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Nutrient Deprivation ◽  
Deletion Mutants ◽  
Wild Type ◽  
Microbial Development ◽  
Type Strains ◽  
Posttranscriptional Level

In contrast to many other cases in microbial development, Aspergillus nidulans conidiophore production initiates primarily as a programmed part of the life cycle rather than as a response to nutrient deprivation. Mutations in the acoD locus result in "fluffy" colonies that appear to grow faster than the wild type and proliferate as undifferentiated masses of vegetative cells. We show that unlike wild-type strains, acoD deletion mutants are unable to make conidiophores under optimal growth conditions but can be induced to conidiate when growth is nutritionally limited. The requirement for acoD in conidiophore development occurs prior to activation of brlA, a primary regulator of development. The acoD transcript is present both in vegetative hyphae prior to developmental induction and in developing cultures. However, the effects of acoD mutations are detectable only after developmental induction. We propose that acoD activity is primarily controlled at the posttranscriptional level and that it is required to direct developmentally specific changes that bring about growth inhibition and activation of brlA expression to result in conidiophore development.

Isolation of a gene required for programmed initiation of development by Aspergillus nidulans

1992 ◽  
Vol 12 (9) ◽  
pp. 3827-3833
Author(s):  
T H Adams ◽  
W A Hide ◽  
L N Yager ◽  
B N Lee
Keyword(s):  
Life Cycle ◽  
Aspergillus Nidulans ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Nutrient Deprivation ◽  
Deletion Mutants ◽  
Wild Type ◽  
Microbial Development ◽  
Type Strains ◽  
Posttranscriptional Level

In contrast to many other cases in microbial development, Aspergillus nidulans conidiophore production initiates primarily as a programmed part of the life cycle rather than as a response to nutrient deprivation. Mutations in the acoD locus result in "fluffy" colonies that appear to grow faster than the wild type and proliferate as undifferentiated masses of vegetative cells. We show that unlike wild-type strains, acoD deletion mutants are unable to make conidiophores under optimal growth conditions but can be induced to conidiate when growth is nutritionally limited. The requirement for acoD in conidiophore development occurs prior to activation of brlA, a primary regulator of development. The acoD transcript is present both in vegetative hyphae prior to developmental induction and in developing cultures. However, the effects of acoD mutations are detectable only after developmental induction. We propose that acoD activity is primarily controlled at the posttranscriptional level and that it is required to direct developmentally specific changes that bring about growth inhibition and activation of brlA expression to result in conidiophore development.

scholarly journals Identification ofvib-1, a Locus Involved in Vegetative Incompatibility Mediated byhet-cinNeurospora crassa

Genetics ◽  
2002 ◽  
Vol 162 (1) ◽  
pp. 89-101 ◽  
Author(s):  
Qijun Xiang ◽  
N Louise Glass
Keyword(s):  
Acid Phosphatase ◽  
Recognition System ◽  
Deletion Mutants ◽  
Wild Type ◽  
Vegetative Incompatibility ◽  
Death Rates ◽  
Self Recognition ◽  
Allelic Differences ◽  
Native Gel ◽  
Type Strains

AbstractA non-self-recognition system called vegetative incompatibility is ubiquitous in filamentous fungi and is genetically regulated by het loci. Different fungal individuals are unable to form viable heterokaryons if they differ in allelic specificity at a het locus. To identify components of vegetative incompatibility mediated by allelic differences at the het-c locus of Neurospora crassa, we isolated mutants that suppressed phenotypic aspects of het-c vegetative incompatibility. Three deletion mutants were identified; the deletions overlapped each other in an ORF named vib-1 (vegetative incompatibility blocked). Mutations in vib-1 fully relieved growth inhibition and repression of conidiation conferred by het-c vegetative incompatibility and significantly reduced hyphal compartmentation and death rates. The vib-1 mutants displayed a profuse conidiation pattern, suggesting that VIB-1 is a regulator of conidiation. VIB-1 shares a region of similarity to PHOG, a possible phosphate nonrepressible acid phosphatase in Aspergillus nidulans. Native gel analysis of wild-type strains and vib-1 mutants indicated that vib-1 is not the structural gene for nonrepressible acid phosphatase, but rather may regulate nonrepressible acid phosphatase activity.

Characterization of the Role of the FluG Protein in Asexual Development of Aspergillus nidulans

Genetics ◽  
2001 ◽  
Vol 158 (3) ◽  
pp. 1027-1036 ◽  
Author(s):  
Cletus A D'Souza ◽  
Bee Na Lee ◽  
Thomas H Adams
Keyword(s):  
Aspergillus Nidulans ◽  
Negative Influence ◽  
Asexual Development ◽  
Wild Type ◽  
Significant Similarity ◽  
Developmental Defects ◽  
Asexual Sporulation ◽  
Type Strains

Abstract We showed previously that a ΔfluG mutation results in a block in Aspergillus nidulans asexual sporulation and that overexpression of fluG activates sporulation in liquid-submerged culture, a condition that does not normally support sporulation of wild-type strains. Here we demonstrate that the entire N-terminal region of FluG (∼400 amino acids) can be deleted without affecting sporulation, indicating that FluG activity resides in the C-terminal half of the protein, which bears significant similarity with GSI-type glutamine synthetases. While FluG has no apparent role in glutamine biosynthesis, we propose that it has an enzymatic role in sporulation factor production. We also describe the isolation of dominant suppressors of ΔfluG(dsg) that should identify components acting downstream of FluG and thereby define the function of FluG in sporulation. The dsgA1 mutation also suppresses the developmental defects resulting from ΔflbA and dominant activating fadA mutations, which both cause constitutive induction of the mycelial proliferation pathway. However, dsgA1 does not suppress the negative influence of these mutations on production of the aflatoxin precursor, sterigmatocystin, indicating that dsgA1 is specific for asexual development. Taken together, our studies define dsgA as a novel component of the asexual sporulation pathway.

scholarly journals Activation of the ADE Genes Requires the Chromatin Remodeling Complexes SAGA and SWI/SNF

2007 ◽  
Vol 6 (8) ◽  
pp. 1474-1485 ◽  
Author(s):  
Rebecca N. Koehler ◽  
Nicole Rachfall ◽  
Ronda J. Rolfes
Keyword(s):  
Chromatin Remodeling ◽  
Growth Conditions ◽  
Specific Response ◽  
Wild Type ◽  
Reporter Expression ◽  
Activator Proteins ◽  
Genome Wide ◽  
A Genome ◽  
Chromatin Remodeling Complexes ◽  
Type Strains

ABSTRACT The activation of the ADE regulon genes requires the pair of transcription factors Bas1 and Pho2. In a genome-wide screen for additional regulators of the pathway, strains with mutations in multiple subunits of the chromatin remodeling complexes SAGA and SWI/SNF were uncovered. These mutants exhibited decreased expression of an ADE5,7-lacZ reporter and native ADE compared to the wild-type strains, but the expression of the BAS1 and PHO2 genes was not substantially decreased. An unregulated Bas1-Pho2 fusion protein depended upon SAGA and SWI/SNF activity to promote transcription of a reporter. A significant but low-level association of Gcn5-myc and Snf2-myc with the ADE5,7 promoter was independent of adenine growth conditions and independent of the presence of the activator proteins Bas1 and Pho2. However, the increase in occupancy of Bas1 and Pho2 at ADE5,7 depended on both SAGA and SWI/SNF. The loss of catalytic activity of both SAGA and SWI/SNF complexes in the gcn5Δ snf2Δ double mutant was severely detrimental to ADE-lacZ reporter expression and native ADE gene expression, indicating complementary roles for these complexes. We conclude that Bas1 and Pho2 do not recruit the SAGA and SWI/SNF complexes to the ADE5,7 promoter but that the remodeling complexes are necessary to increase the binding of Bas1 and Pho2 in response to the adenine regulatory signal. Our data support the model that the SAGA and SWI/SNF complexes engage in global surveillance that is necessary for the specific response by Bas1 and Pho2.

scholarly journals Differentiation of human epidermal cells transformed by SV40.

1983 ◽  
Vol 96 (2) ◽  
pp. 330-337 ◽  
Author(s):  
S P Banks-Schlegel ◽  
P M Howley
Keyword(s):  
Optimal Growth ◽  
Growth Conditions ◽  
Soft Agar ◽  
Epidermal Cells ◽  
Transformed Cells ◽  
Temperature Sensitive ◽  
Nonpermissive Temperature ◽  
Wild Type ◽  
Human Epidermal Cells ◽  
Growth Properties

Human epidermal cells were transformed with DNA from wild-type SV40 virus or with DNA from a temperature-sensitive A mutant (tsA209). The SV40-transformed cells differed from nontransformed cells in their morphologic appearance, growth properties, and expression of certain characteristics associated with differentiation. The transformed cells were more variable in size and shape than their nontransformed counterparts and were less stratified and less keratinized. While the growth properties of the cells were similar under optimal growth conditions, the transformed cells could be propagated under stringent growth conditions that did not support the growth of nontransformed human epidermal cells. The transformants still required a 3T3 feeder layer for growth, remained anchorage dependent as assayed in soft agar, and were not tumorigenic in athymic nude mice. The expression of certain differentiated functions of the human epidermal cell, the presence of keratins and cross-linked envelopes, was decreased in the transformed cells, and these functions could be restored at the nonpermissive temperature in the tsA209 transformed cells.

scholarly journals The highly divergent beta-tubulins of Aspergillus nidulans are functionally interchangeable.

1989 ◽  
Vol 109 (5) ◽  
pp. 2267-2274 ◽  
Author(s):  
G S May
Keyword(s):  
Aspergillus Nidulans ◽  
Nuclear Division ◽  
Selectable Marker ◽  
Wild Type ◽  
Tubulin Gene ◽  
Beta Tubulin ◽  
Tubulin Genes ◽  
Internal Gene ◽  
Type Strains ◽  
Beta Tubulin Gene

An internal 1.4-kb Bst EII fragment was used to disrupt the benA gene and establish heterokaryons. The heterokaryons demonstrated that the molecular disruption of benA results in a recessive benA null mutation. Conidia from a heterokaryon swell and germinate but cannot undergo nuclear division and are thus inviable. A chimeric beta-tubulin gene was constructed with the benA promoter driving the tubC structural gene. This chimeric gene construction was placed on a plasmid containing a selectable marker for Aspergillus transformation and the gene disrupting fragment of benA. Integration of this plasmid at benA by the internal gene disrupting fragment of benA simultaneously disrupts the benA gene and replaces it with the chimeric beta-tubulin gene, rescuing the benA null generated by the integration. Strains generated by this procedure contain only tubC beta-tubulin for all beta-tubulin functions. Strains having only tubC beta-tubulin are viable and exhibit no detectable microtubule dysfunction though they are more sensitive than wild-type strains to the antimicrotubule drug benomyl. It is concluded that the two beta-tubulin genes of Aspergillus nidulans, though highly divergent, are interchangeable.

scholarly journals Identification and Characterization of theNeisseria gonorrhoeaeMscS-Like Mechanosensitive Channel

2018 ◽  
Vol 86 (6) ◽  
Author(s):  
Zhemin Wang ◽  
Xiaomin Wang ◽  
Ping Lu ◽  
Chunshan Ni ◽  
Yuezhou Li ◽  
...  
Keyword(s):  
Turgor Pressure ◽  
Bacterial Pathogen ◽  
Mechanosensitive Channel ◽  
Infection Model ◽  
Deletion Mutants ◽  
Mechanosensitive Channels ◽  
Wild Type ◽  
Content Type ◽  
Type Strains

ABSTRACTMechanosensitive channels are ubiquitous in bacteria and provide an essential mechanism to survive sudden exposure to a hypo-osmotic environment by the sensing and release of increased turgor pressure. No mechanosensitive channels have thus far been identified and characterized for the human-specific bacterial pathogenNeisseria gonorrhoeae. In this study, we identified and characterized theN. gonorrhoeaeMscS-like mechanosensitive channel (Ng-MscS). Electrophysiological analyses by the patch clamp method showed that Ng-MscS is stretch activated and contains pressure-dependent gating properties. Further mutagenesis studies of critical residues forming the hydrophobic vapor lock showed that gain-of-function mutations in Ng-MscS inhibited bacterial growth. Subsequent analysis of the function of Ng-MscS inN. gonorrhoeaeby osmotic down-shock assays revealed that the survival of Ng-mscSdeletion mutants was significantly reduced compared with that of wild-type strains, while down-shock survival was restored upon the ectopic complementation ofmscS. Finally, to investigate whether Ng-MscS is important forN. gonorrhoeaeduring infections, competition assays were performed by using a murine vaginal tract infection model. Ng-mscSdeletion mutants were outcompeted byN. gonorrhoeaewild-type strains for colonization and survival in this infection model, highlighting that Ng-MscS contributes toin vivocolonization and survival. Therefore, Ng-MscS might be a promising target for the future development of novel antimicrobials.

scholarly journals Phenol oxidases produced by mutant and wild-type strains of Aspergillus nidulans

1969 ◽  
Vol 114 (1) ◽  
pp. 10P-10P
Author(s):  
S D Martinelli ◽  
B W Bainbridge ◽  
S J Pirt
Keyword(s):  
Aspergillus Nidulans ◽  
Wild Type ◽  
Phenol Oxidases ◽  
Type Strains

Although calnexin is essential in S. pombe, its highly conserved central domain is dispensable for viability

1999 ◽  
Vol 112 (23) ◽  
pp. 4449-4460 ◽  
Author(s):  
A. Elagoz ◽  
M. Callejo ◽  
J. Armstrong ◽  
L.A. Rokeach
Keyword(s):  
Central Region ◽  
Mammalian Cells ◽  
Normal Growth ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Wild Type ◽  
Lectin Activity ◽  
Central Domain ◽  
Folding Intermediates ◽  
Mutant Cells

In mammalian cells, the calnexin/calreticulin chaperones play a key role in glycoprotein folding and its control within the endoplasmic reticulum (ER), by interacting with folding intermediates via their monoglucosylated glycans. This lectin activity has been mapped in mammalian calnexin/calreticulin chaperones to the central region, which is a highly conserved feature of calnexin/calreticulin molecules across species. The central domain has also been implicated in Ca(2+) binding, and it has been proposed to be involved in the regulation of calcium homeostasis in the ER. Herein, we show that although the Schizosaccharomyces pombe calnexin is essential for viability, cells lacking its 317-amino-acid highly conserved central region are viable under normal growth conditions. However, the central region appears to be necessary for optimal growth under high ER-stress, suggesting that this region is important under extreme folding situations (such as DTT and temperature). The minimal length of calnexin required for viability spans the C-terminal 123 residues. Furthermore, cells with the central domain of the protein deleted were affected in their morphology at 37 degrees C, probably due to a defect in cell wall synthesis, although these mutant cells exhibited the same calcium tolerance as wild-type cells at 30 degrees C.

A GENETIC STUDY OF ELECTROPHORETICALLY VARIANT EXTRACELLULAR AMYLOLYTIC ENZYMES OF WILD-TYPE STRAINS OF ASPERGILLUS NIDULANS

1973 ◽  
Vol 15 (2) ◽  
pp. 275-287 ◽  
Author(s):  
K. C. Kurzeja ◽  
E. D. Garber
Keyword(s):  
Aspergillus Nidulans ◽  
Gel Electrophoresis ◽  
Soluble Starch ◽  
Defined Medium ◽  
Wild Type ◽  
Amylolytic Enzymes ◽  
Freeze Dried ◽  
Organic Carbon Source ◽  
Duplicate Loci ◽  
Type Strains

Ninety strains assigned to Aspergillus nidulans produced extracellular amylolytic enzymes in a defined medium containing soluble starch as the organic carbon source. Acrylamide gel electrophoresis of freeze-dried culture filtrates gave 6-9 sites of amylolytic activity accommodated by nine patterns. Eighty-one strains exhibited pattern 1 or 2 and not more than two displayed one of the remaining seven patterns. Crosses between strains with different patterns succeeded only for strains with pattern 1 or 2. Esterase and phosphatase zymograms for mycelial extracts indicated that strains with amylase pattern 1 or 2 are A. nidulans, while the strains with the other amylase patterns are probably cryptic or sibling species. Two codominant alleles are responsible for the different electrophoretic mobility of one pair of amylolytic sites in zone 2 which distinguishes patterns 1 and 2. The pair of sites may be determined by duplicate loci.

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