Identification of seven new cut genes involved in Schizosaccharomyces pombe mitosis

1993 ◽  
Vol 105 (1) ◽  
pp. 135-143 ◽  
Author(s):  
I. Samejima ◽  
T. Matsumoto ◽  
Y. Nakaseko ◽  
D. Beach ◽  
M. Yanagida
Keyword(s):  
Topoisomerase Ii ◽  
Nuclear Division ◽  
Spindle Pole ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Dna Topoisomerase ◽  
Isolation And Characterization ◽  
Genes Encoding ◽  
Mixed Phenotype

Fission yeast cut mutants cause cytokinesis in the absence of normal nuclear division. These mutants show abnormal uncoupled mitosis and are known to be the result of mutations in the genes encoding DNA topoisomerase II, proteins related to spindle pole duplication, and a kinesin-related mitotic motor. We have screened 717 temperature-sensitive (ts) mutants by individually observing their cytological phenotypes at the restrictive temperature, and have newly isolated 25 cut mutants. Genetic analyses indicate that 14 of them fall into five previously identified loci, namely, top2, cut1, cut5, cut7 and cut9, whereas nine have been mapped onto seven new loci, designated cut13 to cut19. The cytological phenotypes of the newly identified cut mutants can be classified into three groups. One group consists of mutants in which a portion of the nuclear chromatin is stretched by the elongated spindle but the entire nucleus is not separated, reminiscent of, but not identical to, the phenotypes of top2 and cut1; mutants cut14-208, cut15-85, cut16-267 and cut17-275 display such a phenotype. Another group exhibits non-disjunctioned and condensed chromosomes in the presence of the spindle; cut13-131 belongs to this group. The cut19-708 mutant has also been found to have condensed chromosomes. The remaining group has a mixed phenotype of the above two groups; namely, stretched chromatin and condensed chromosomes; cut18-447 exhibits such a phenotype. The isolation and characterization of the mutated genes will be the subjects of future investigations.

scholarly journals CDC37 is required for p60v-src activity in yeast.

1996 ◽  
Vol 7 (9) ◽  
pp. 1405-1417 ◽  
Author(s):  
B Dey ◽  
J J Lightbody ◽  
F Boschelli
Keyword(s):  
Protein Tyrosine Kinase ◽  
Wild Type Strain ◽  
Active Form ◽  
Biologically Active ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Wild Type ◽  
Isolation And Characterization ◽  
Genes Encoding

Mutations in genes encoding the molecular chaperones Hsp90 and Ydj1p suppress the toxicity of the protein tyrosine kinase p60v-src in yeast by reducing its levels or its kinase activity. We describe isolation and characterization of novel p60v-src-resistant, temperature-sensitive cdc37 mutants, cdc37-34 and cdc37-17, which produce less p60v-src than the parental wild-type strain at 23 degrees C. However, p60v-src levels are not low enough to account for the resistance of these strains. Asynchronously growing cdc37-34 and cdc37-17 mutants arrest in G1 and G2/M when shifted from permissive temperatures (23 degrees C) to the restrictive temperature (37 degrees C), but hydroxyurea-synchronized cdc37-34 and cdc37-17 mutants arrest in G2/M when released from the hydroxyurea block and shifted from 23 to 37 degrees C. The previously described temperature-sensitive cdc37-1 mutant is p60v-src-sensitive and produces wild-type amounts of p60v-src at permissive temperatures but becomes p60v-src-resistant at its restrictive temperature, 38 degrees C. In all three cdc37 mutants, inactivation of Cdc37p by incubation at 38 degrees C reduces p60v-src-dependent tyrosine phosphorylation of yeast proteins to low or undetectable levels. Also, p60v-src levels are enriched in urea-solubilized extracts and depleted in detergent-solubilized extracts of all three cdc37 mutants prepared from cells incubated at the restrictive temperature. These results suggest that Cdc37p is required for maintenance of p60v-src in a soluble, biologically active form.

scholarly journals CHARACTERIZATION OF TEMPERATURE-SENSITIVE, FERTILIZATION-DEFECTIVE MUTANTS OF THE NEMATODE CAENORHABDITIS ELEGANS

Genetics ◽  
1978 ◽  
Vol 88 (2) ◽  
pp. 285-303 ◽  
Author(s):  
Samuel Ward ◽  
Johji Miwa
Keyword(s):  
Caenorhabditis Elegans ◽  
Sensitive Period ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Wild Type ◽  
Normal Numbers ◽  
Primary Defect ◽  
Isolation And Characterization ◽  
Pass Through

ABSTRACT The isolation and characterization of three Caenorhabditis elegans temperature-sensitive mutants that are defective at fertilization are described. All three are alleles of the gene fer-1. At the restrictive temperature of 25°, mutant hermaphrodites make sperm and oocytes in normal numbers. No oocytes are fertilized, although they pass through the spermatheca and uterus normally. The oocytes can be fertilized by sperm transferred by wild-type males, indicating that the mutant defect is in the sperm. The temperature-sensitive period for the mutants coincides with spermatogenesis. Sperm made by mutants at 25° cannot be distinguished from wild-type sperm by light microscopy. The sperm do contact oocytes in mutant hermaphrodites, but do not fertilize. Mutant sperm appear to be nonmotile. Mutant males are also sterile when grown at 25°. They transfer normal numbers of sperm to hermaphrodites at mating, but these sperm fail to migrate to the spermatheca and are infertile. The phenotype of these mutants is consistent with a primary defect in sperm motility, but the cause of this defect is not known.

Isolation and characterization of DNA topoisomerase II from cauliflower inflorescences

1986 ◽  
Vol 6 (3) ◽  
pp. 137-144 ◽  
Author(s):  
Hideki Fukata ◽  
Kazue Ohgami ◽  
Hirosuke Fukasawa
Keyword(s):  
Topoisomerase Ii ◽  
Dna Topoisomerase Ii ◽  
Dna Topoisomerase ◽  
Isolation And Characterization

scholarly journals Isolation and characterization of chromosome-gain and increase-in-ploidy mutants in yeast.

Genetics ◽  
1993 ◽  
Vol 135 (3) ◽  
pp. 677-691 ◽  
Author(s):  
C S Chan ◽  
D Botstein
Keyword(s):  
Spindle Pole Body ◽  
Temperature Shift ◽  
Spindle Pole ◽  
Temperature Sensitive ◽  
Chromosome Gain ◽  
Recessive Mutations ◽  
Isolation And Characterization ◽  
Complementation Groups ◽  
Bud Growth

Abstract We have developed a colony papillation assay for monitoring the copy number of genetically marked chromosomes II and III in Saccharomyces cerevisiae. The unique feature of this assay is that it allows detection of a gain of the marked chromosomes even if there is a gain of the entire set of chromosomes (increase-in-ploidy). This assay was used to screen for chromosome-gain or increase-in-ploidy mutants. Five complementation groups have been defined for recessive mutations that confer an increase-in-ploidy (ipl) phenotype, which, in each case, cosegregates with a temperature-sensitive growth phenotype. Four new alleles of CDC31, which is required for spindle pole body duplication, were also recovered from this screen. Temperature-shift experiments with ipl1 cells show that they suffer severe nondisjunction at 37 degrees. Similar experiments with ipl2 cells show that they gain entire sets of chromosomes and become arrested as unbudded cells at 37 degrees. Molecular cloning and genetic mapping show that IPL1 is a newly identified gene, whereas IPL2 is allelic to BEM2, which is required for normal bud growth.

scholarly journals Identification and characterization of Aspergillus nidulans mutants defective in cytokinesis.

Genetics ◽  
1994 ◽  
Vol 136 (2) ◽  
pp. 517-532 ◽  
Author(s):  
S D Harris ◽  
J L Morrell ◽  
J E Hamer
Keyword(s):  
Aspergillus Nidulans ◽  
Nuclear Division ◽  
Temperature Shift ◽  
Mitotic Division ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
The Third ◽  
Septum Formation ◽  
New Genes

Abstract Filamentous fungi undergo cytokinesis by forming crosswalls termed septa. Here, we describe the genetic and physiological controls governing septation in Aspergillus nidulans. Germinating conidia do not form septa until the completion of their third nuclear division. The first septum is invariantly positioned at the basal end of the germ tube. Block-and-release experiments of nuclear division with benomyl or hydroxyurea, and analysis of various nuclear division mutants demonstrated that septum formation is dependent upon the third mitotic division. Block-and-release experiments with cytochalasin A and the localization of actin in germlings by indirect immunofluorescence showed that actin participated in septum formation. In addition to being concentrated at the growing hyphal tips, a band of actin was also apparent at the site of septum formation. Previous genetic analysis in A. nidulans identified four genes involved in septation (sepA-D). We have screened a new collection of temperature sensitive (ts) mutants of A. nidulans for strains that failed to form septa at the restrictive temperature but were able to complete early nuclear divisions. We identified five new genes designated sepE, G, H, I and J, along with one additional allele of a previously identified septation gene. On the basis of temperature shift experiments, nuclear counts and cell morphology, we sorted these cytokines mutants into three phenotypic classes. Interestingly, one class of mutants fails to form septa and fails to progress past the third nuclear division. This class of mutants suggests the existence of a regulatory mechanism in A. nidulans that ensures the continuation of nuclear division following the initiation of cytokinesis.

Isolation and characterization of the genes encoding antimicrobial neutrophil cationic peptides, defensins.

Ensho ◽  
1995 ◽  
Vol 15 (1) ◽  
pp. 33-41
Author(s):  
Isao Nagaoka ◽  
Noriko Ishihara ◽  
Akimasa Someya ◽  
Kazuhisa Iwabuchi ◽  
Shin Yomogida ◽  
...  
Keyword(s):  
Cationic Peptides ◽  
Isolation And Characterization ◽  
Genes Encoding
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