scholarly journals Enhancers of conidiation mutants in Aspergillus nidulans.

Genetics ◽  
1994 ◽  
Vol 137 (1) ◽  
pp. 79-85
Author(s):  
D H Gems ◽  
A J Clutterbuck
Keyword(s):  
Linkage Group ◽  
Aspergillus Nidulans ◽  
Double Mutant ◽  
Slight Modification ◽  
Temperature Sensitive ◽  
Permissive Temperature ◽  
Wild Type ◽  
Group V ◽  
Group I

Abstract Mutants at a number of loci, designated sthenyo, have been isolated as enhancers of the oligoconidial mutations at the medA locus. Two loci have been mapped: sthA on linkage group I, and sthB on linkage group V. Two probable alleles have been identified at each locus but two further mutants were unlinked to either sthA or sthB. Neither sthA nor sthB mutants have conspicuous effects on morphology on their own, nor could the sthA1 sthB2 double mutant be distinguished from wild type. Mutants at both loci also interact with the temperature-sensitive brlA42 mutant at the permissive temperature to give a phenotype described as "Abacoid." sthA1 also induces a slight modification of the phenotype of an abaA mutant. We conclude that sthenyo genes act mainly at the phialide stage of conidiation. We also describe the isolation of new medA mutants arising spontaneously as outgrowths on brlA42 colonies.

SOME GENETIC AND PHYSIOLOGICAL CHARACTERISTICS OF UREASE-DEFECTIVE STRAINS OF NEUROSPORA CRASSA

1971 ◽  
Vol 13 (2) ◽  
pp. 256-269 ◽  
Author(s):  
Philip Haysman ◽  
H. Branch Howe Jr.
Keyword(s):  
Linkage Group ◽  
Nitrogen Source ◽  
Urease Activity ◽  
Temperature Sensitive ◽  
Sole Nitrogen Source ◽  
Group V ◽  
Group I ◽  
Mutant Strains

Fourteen mutant strains have been isolated which differ from wild type with respect to urease activity: Seven strains lack detectable activity in vivo and in vitro, B1, C21 and allele 601, D1 and allele D3, D2, and W2, and fail to grow with urea as sole nitrogen source; seven have activity in vivo and varying amounts in vitro, A7, E3, E7, R2, S3, and temperature-sensitive strains C5 and K3. Strains D1 and D3 are allelic to Kolmark's ure-1; W2, to Kolmark's ure-2. Strain D2, which is either allelic or closely linked to ure-1, complements none of the strains lacking urease activity nor three of the strains having defective activity, and may be a regulatory mutant. Strains B1, C21 and allele 601 represent two previously unreported loci in linkage group I. Only two of the seven swains having defective urease activity have been mapped, A7 and S3, and have been assigned to linkage group V. These seven strains grow readily on Vogel's medium modified by having urea as sole nitrogen source but not on W-M medium similarly modified; growth is restricted on modified Vogel's medium as well, however, if the initial concentration of nitrogen, as urea, is suitably adjusted to exceed that of phosphorus.

scholarly journals Structural gene for ornithine decarboxylase in Neurospora crassa

1985 ◽  
Vol 5 (6) ◽  
pp. 1301-1306
Author(s):  
P Eversole ◽  
J J DiGangi ◽  
T Menees ◽  
R H Davis
Keyword(s):  
Linkage Group ◽  
Neurospora Crassa ◽  
Ornithine Decarboxylase ◽  
Structural Gene ◽  
Minimal Medium ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Group V

To define the structural gene for ornithine decarboxylase (ODC) in Neurospora crassa, we sought mutants with kinetically altered enzyme. Four mutants, PE4, PE7, PE69, and PE85, were isolated. They were able to grow slowly at 25 degrees C on minimal medium but required putrescine or spermidine supplementation for growth at 35 degrees C. The mutants did not complement with one another or with ODC-less spe-1 mutants isolated in earlier studies. In all of the mutants isolated to date, the mutations map at the spe-1 locus on linkage group V. Strains carrying mutations PE4, PE7, and PE85 displayed a small amount of residual ODC activity in extracts. None of them had a temperature-sensitive enzyme. The enzyme of the PE85 mutant had a 25-fold higher Km for ornithine (5mM) than did the enzyme of wild-type or the PE4 mutant (ca. 0.2 mM). The enzyme of this mutant was more stable to heat than was the wild-type enzyme. These characteristics were normal in the mutant carrying allele PE4. The mutant carrying PE85 was able to grow well at 25 degrees C and weakly at 35 degrees C with ornithine supplementation. This mutant and three ODC-less mutants isolated previously displayed a polypeptide corresponding to ODC in Western immunoblots with antibody raised to purified wild-type ODC. We conclude that spe-1 is the structural gene for the ODC.

scholarly journals Formal and physiological genetics of ascospore colour in Aspergillus nidulans

1963 ◽  
Vol 4 (2) ◽  
pp. 276-283 ◽  
Author(s):  
D. Apirion
Keyword(s):  
Linkage Group ◽  
Aspergillus Nidulans ◽  
Nitrous Acid ◽  
Group Iv ◽  
Locus Symbol ◽  
Parental Genotype ◽  
Wild Type ◽  
Uv Treatment ◽  
Group I ◽  
Group Ii

By nitrous acid or UV treatment ascospore colour mutants of two kinds, blue and colourless, were obtained in Aspergillus nidulans (wild-type has red ascospores). Four blue mutants were located in linkage group II within 0·5 unit of one another (locus symbol: b11). Of the colourless mutants, four were located in linkage group I within one unit of one another (locus symbol: c16), and one in linkage group IV (locus symbol: c14). In diploids the mutants were recessive. Colourless was epistatic to blue.In crosses these characters behaved as ‘non-autonomous’ both in the ascospores and in the asci; all the ascospores of the asci in one perithecium as well as the perithecium wall were of the same colour. In crosses between strains with blue perithecia and strains with colourless perithecia, red, blue and colourless perithecia were found; each type included both crossed and selfed perithecia. Red selfed perithecia were of either parental genotype but blue or colourless selfed perithecia always had the corresponding genotype.The phenotype of the perithecium (perithecial wall and ascospores) is considered to be determined by the homo- or heterokaryotic constitution of the protoperi-thecium which gave origin to it.

scholarly journals Structural gene for ornithine decarboxylase in Neurospora crassa.

1985 ◽  
Vol 5 (6) ◽  
pp. 1301-1306 ◽  
Author(s):  
P Eversole ◽  
J J DiGangi ◽  
T Menees ◽  
R H Davis
Keyword(s):  
Linkage Group ◽  
Neurospora Crassa ◽  
Ornithine Decarboxylase ◽  
Structural Gene ◽  
Minimal Medium ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Group V

To define the structural gene for ornithine decarboxylase (ODC) in Neurospora crassa, we sought mutants with kinetically altered enzyme. Four mutants, PE4, PE7, PE69, and PE85, were isolated. They were able to grow slowly at 25 degrees C on minimal medium but required putrescine or spermidine supplementation for growth at 35 degrees C. The mutants did not complement with one another or with ODC-less spe-1 mutants isolated in earlier studies. In all of the mutants isolated to date, the mutations map at the spe-1 locus on linkage group V. Strains carrying mutations PE4, PE7, and PE85 displayed a small amount of residual ODC activity in extracts. None of them had a temperature-sensitive enzyme. The enzyme of the PE85 mutant had a 25-fold higher Km for ornithine (5mM) than did the enzyme of wild-type or the PE4 mutant (ca. 0.2 mM). The enzyme of this mutant was more stable to heat than was the wild-type enzyme. These characteristics were normal in the mutant carrying allele PE4. The mutant carrying PE85 was able to grow well at 25 degrees C and weakly at 35 degrees C with ornithine supplementation. This mutant and three ODC-less mutants isolated previously displayed a polypeptide corresponding to ODC in Western immunoblots with antibody raised to purified wild-type ODC. We conclude that spe-1 is the structural gene for the ODC.

scholarly journals Aspergillus nidulans Protein O-Mannosyltransferases Play Roles in Cell Wall Integrity and Developmental Patterning

2009 ◽  
Vol 8 (10) ◽  
pp. 1475-1485 ◽  
Author(s):  
Thanyanuch Kriangkripipat ◽  
Michelle Momany
Keyword(s):  
Cell Wall ◽  
Aspergillus Nidulans ◽  
Double Mutant ◽  
Elevated Temperatures ◽  
Cell Wall Integrity ◽  
Wild Type ◽  
Spatial Cues ◽  
Developmental Patterning ◽  
In The Wild ◽  
Increased Sensitivity

ABSTRACT Protein O-mannosyltransferases (Pmts) initiate O-mannosyl glycan biosynthesis from Ser and Thr residues of target proteins. Fungal Pmts are divided into three subfamilies, Pmt1, -2, and -4. Aspergillus nidulans possesses a single representative of each Pmt subfamily, pmtA (subfamily 2), pmtB (subfamily 1), and pmtC (subfamily 4). In this work, we show that single Δpmt mutants are viable and have unique phenotypes and that the ΔpmtA ΔpmtB double mutant is the only viable double mutant. This makes A. nidulans the first fungus in which all members of individual Pmt subfamilies can be deleted without loss of viability. At elevated temperatures, all A. nidulans Δpmt mutants show cell wall-associated defects and increased sensitivity to cell wall-perturbing agents. The Δpmt mutants also show defects in developmental patterning. Germ tube emergence is early in ΔpmtA and more frequent in ΔpmtC mutants than in the wild type. In ΔpmtB mutants, intrahyphal hyphae develop. All Δpmt mutants show distinct conidiophore defects. The ΔpmtA strain has swollen vesicles and conidiogenous cells, the ΔpmtB strain has swollen conidiophore stalks, and the ΔpmtC strain has dramatically elongated conidiophore stalks. We also show that AN5660, an ortholog of Saccharomyces cerevisiae Wsc1p, is modified by PmtA and PmtC. The Δpmt phenotypes at elevated temperatures, increased sensitivity to cell wall-perturbing agents and restoration to wild-type growth with osmoticum suggest that A. nidulans Pmts modify proteins in the cell wall integrity pathway. The altered developmental patterns in Δpmt mutants suggest that A. nidulans Pmts modify proteins that serve as spatial cues.

Growth Properties of Neural Cell Lines Immortalized with the Tsa58 Allele of Sv40 Large T Antigen

1997 ◽  
Vol 6 (3) ◽  
pp. 231-238 ◽  
Author(s):  
M.E. Truckenmiller ◽  
Ora Dillon-Carter ◽  
Carlo Tornatore ◽  
Henrietta Kulaga ◽  
Hidetoshi Takashima ◽  
...  
Keyword(s):  
Amino Acid ◽  
Cell Line ◽  
Cell Lines ◽  
T Antigen ◽  
Temperature Sensitive ◽  
Permissive Temperature ◽  
Large T Antigen ◽  
Wild Type ◽  
Sv40 Large T Antigen ◽  
Growth Properties

In vitro growth properties of three CNS-derived cell lines were compared under a variety of culture conditions. The M213-20 and J30a cell lines were each derived from embryonic CNS culture with the temperature-sensitive (ts) allele of SV40 large T antigen, tsA58, while the A7 cell line was immortalized using wild-type SV40 large T antigen. Cells immortalized with tsA58 SV40 large T proliferate at the permissive temperature, 33° C, while growth is expected to be suppressed at the nonpermissive temperature, 39.5°C. Both the M213-20 and J30a cell lines were capable of proliferating at 39.5°C continuously for up to 6 mo. All three cell lines showed no appreciable differences in growth rates related to temperature over a 7-day period in either serum-containing or defined serum-free media. The percentage of cells in S-phase of the cell cycle did not decrease or was elevated at 39.5°C for all three cell lines. After 3 wk at 39.5°C, the three cell lines also showed positive immunostaining using two monoclonal antibodies reacting with different epitopes of SV40 large T antigen. Double strand DNA sequence analyses of a 300 base pair (bp) fragment of the large T gene from each cell line, which included the ts locus, revealed mutations in both the J30a and M213-20 cell lines. The J30a cell line ts mutation had reverted to wild type, and two additional loci with bp substitutions with predicted amino acid changes were also found. While the ts mutation of the M213-20 cells was retained, an additional bp substitution with a predicted amino acid change was found. The A7 cell line sequence was identical to the reference wild-type sequence. These findings suggest that (a) nucleic acid sequences in the temperature-sensitive region of the tsA58 allele of SV40 large T are not necessarily stable, and (b) temperature sensitivity of cell lines immortalized with tsA58 is not necessarily retained.

Correction of the defect in initiation of DNA replication in a temperature-sensitive mutant hamster cell line by in vitro addition of extracts from normal cells

1985 ◽  
Vol 5 (4) ◽  
pp. 902-905
Author(s):  
M Narkhammar ◽  
R Hand
Keyword(s):  
Cell Line ◽  
Nuclear Extract ◽  
Cell Extract ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Wild Type ◽  
Whole Cell ◽  
Mutant Cells

ts BN-2 is a temperature-sensitive hamster cell line that is defective in DNA synthesis at the restrictive temperature. The mutant expresses its defect during in vitro replication in whole-cell lysates. Addition of a high-salt-concentration extract from wild-type BHK-21, revertant RBN-2, or CHO cells to mutant cells lysed with 0.01% Brij 58 increased the activity in the mutant three- to fourfold, so that it reached 85% of the control value, and restored replicative synthesis. The presence of extract had an insignificant effect on wild-type and revertant replication and on mutant replication at the permissive temperature. Extract prepared from mutant cells was less effective than the wild-type cell extract was. Also, the stimulatory activity was more heat labile in the mutant than in the wild-type extract. Nuclear extract was as active as whole-cell extract.

bimA encodes a member of the tetratricopeptide repeat family of proteins and is required for the completion of mitosis in Aspergillus nidulans

1991 ◽  
Vol 99 (4) ◽  
pp. 711-719
Author(s):  
K.L. O'Donnell ◽  
A.H. Osmani ◽  
S.A. Osmani ◽  
N.R. Morris
Keyword(s):  
Amino Acid ◽  
Aspergillus Nidulans ◽  
Essential Gene ◽  
Tetratricopeptide Repeat ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Amino Acid Residues ◽  
Wild Type ◽  
Reading Frame ◽  
Integrative Transformation

The recessive, temperature-sensitive bimA1 mutation of Aspergillus nidulans blocks nuclei in metaphase at restrictive temperature. To determine whether the bimA product is essential, integrative transformation was used to create a mutation in the bimA gene. The mutation was maintained in a heterokaryon and the phenotype of spores produced by the heterokaryon was analyzed. Molecular disruption of the wild-type bimA gene is recessive in the heterokaryon and causes a metaphase block, demonstrating that bimA is an essential gene for mitosis. bimA was cloned by DNA-mediated complementation of its mutant phenotype at restrictive temperature, and the nucleotide sequence of a full-length cDNA was determined. A single large open reading frame was identified in the cDNA sequence, which predicts a protein containing 806 amino acid residues that is related (30.4% identity) to the Schizosaccharomyces pombe nuc2+ gene product, which also is required for completion of mitosis. The sequence of the bimA gene indicates that it is a member of a family of mostly nuclear proteins that contain a degenerate 34 amino acid repeat, the TPR (tetratricopeptide repeat) gene family.

Molecular genetic studies of the Cdc7 protein kinase and induced mutagenesis in yeast.

Genetics ◽  
1992 ◽  
Vol 132 (1) ◽  
pp. 53-62 ◽  
Author(s):  
R E Hollingsworth ◽  
R M Ostroff ◽  
M B Klein ◽  
L A Niswander ◽  
R A Sclafani
Keyword(s):  
Protein Kinase ◽  
Insertional Mutagenesis ◽  
Molecular Genetic ◽  
Dna Lesions ◽  
Temperature Sensitive ◽  
Permissive Temperature ◽  
Wild Type ◽  
Mutant Proteins ◽  
Repair Enzymes ◽  
Induced Mutagenesis

Abstract The Saccharomyces cerevisiae CDC7 gene encodes a protein kinase that functions in DNA replication, repair, and meiotic recombination. The sequence of several temperature-sensitive (ts) cdc7 mutations was determined and correlated with protein kinase consensus domain structure. The positions of these ts alleles suggests some general principles for predicting ts protein kinase mutations. Pedigree segregation lag analysis demonstrated that all of the mutant proteins are less active or less stable than wild-type Cdc7p. Two new mutations were constructed, one by site-directed and the other by insertional mutagenesis. All of the cdc7 mutants were assayed for induced mutagenesis in response to mutagenic agents at the permissive temperature. Some cdc7 mutants were found to be hypomutable, while others are hypermutable. The differences in mutability are observed most clearly when log phase cells are used. Both hypo- and hypermutability are recessive to wild type. Cdc7p may participate in DNA repair by phosphorylating repair enzymes or by altering chromatin structure to allow accessibility to DNA lesions.

DOMINANT-AND-RECESSIVE EPISTASIS IN A HOMEOTIC MOSQUITO MUTANT

1976 ◽  
Vol 18 (4) ◽  
pp. 593-600
Author(s):  
Satish C. Bhalla
Keyword(s):  
Linkage Group ◽  
Wild Type ◽  
Pure Strain ◽  
Group Iii ◽  
Homeotic Mutant ◽  
Culex Pipiens Fatigans ◽  
Group I ◽  
Ratio Data ◽  
Independent Segregation ◽  
Selection For

Folowing selection for 15 generations a pure strain of a homeotic mutant spur was isolated from a Brazilian population of the mosquito Culex pipiens fatigans. Monohybrid crosses showed a 13:3 segregation indicating dominant-and-recessive epistasis for wild-type vs. spur. This implies that a dominant allele at one locus and a recessive at the other interact to produce the mutant phenotype. Dihybrid crosses with linkage group II markers yellow and ruby gave 39:13:9:3 ratios indicating independent segregation. However, the dihybrid cross with linkage group I marker maroon showed a highly significant departure from 39:13:9:3 ratio. Data available indicate that the phenotype spur is controlled by a dominant epistat in linkage group III and a recessive epistat (approximately 31.9 crossover units from maroon) in linkage group I.

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