Meiotic Cells

It has been shown for Saccharomyces dind for Schizosaccharo-myces that cells undergoing meiosis are particularly prone to certain types of mutational changes, frameshift mutations above all. The procedure followed is to divide a population of mitotic cells into one fraction which is analyzed for its content of spontaneous mutants while the other fraction is induced to undergo meiosis, after which the asci formed are 

In conclusion, it must be emphasized here that inclusion of a test using meiotic cells is required if one intends to rule out mutagenicity of an agent in yeast. However, more work has to be done to elucidate and substantiate meiotic mutagenesis as a situation where chemicals not genetically active in mitotic cells exert a definite genetic effect. 

Eukaryotic cells carry genetic information not only in the nucleus but also in organelles, such as mitochondria in yeast. In addition to that, there are cytoplasmic genetic factors known which cannot be associated with cell organelles, such as the killer factor and the factor. 

Various regimens inducing the RD phenotype have been proven not to be mutagenic in any other system in yeast KCN, incubation in certain dilute media, and growth at elevated temperature. This shows very clearly that a change from an RG to a stable RD phenotype can be induced not only by definite mutagens. 

The ease with which RD mutants can be obtained in certain yeasts indicates only a very weakly established cell organelle 

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Observations from various systems, including yeast, suggest that phosphorylation and dephosphorylation of proteins play important roles in the mitotic and meiotic cell cycles and the differentiation of germ cells. Extracts from mitotic HeLa cells contained phosphoproteins also present in other mitotic and meiotic cell types, but not in interphase cells (Davis et al., 1983). Exposure of Xenopus oocytes to progesterone results in a burst of protein phosphorylation shortly before GVBD (Mailer et al.,... 

Choi, T Aoki, E, Yamashita, M Nagahama, Y and Kohmoto, K. (1992). Direct activation of the p34cprotein kinase without preceding phosphorylation during meiotic cell cycles in mouse oocytes. Biomed. Res. 13 423-427. 

Nishizawa, M., Okazaki, K., Furuno, N., Watanabe, N., and Sagata, N. (1992). The second-codon rule and autosphophorylation govern the stability and activity of Mos during the meiotic cell cycle in Xenopus oocytes. EMBO J. 11 2433-2446. 

Rime, H., Neant, I., Guerrier, P., and Ozon, R. (1989). 6-Dimethylaminopurine (6-DMAP), a reversible inhibitor of the transition to metaphase during the first meiotic cell division of the mouse oocyte. Dev. Biol. 133 169-179. 

The c-mos proto-oncogene is unique in being specifically expressed in male and female germ cells, where it appears to play a central role in regulating the meiotic cell cycle. Its function is best understood in... 

Nurse That is in mitotic cells. In meiotic cells, is there a role for Polo ... 

Scully, R., et al.. Association of BRCAl with Rad51 in mitotic and meiotic cells. Cell, 1997, 88(2), 265— 75. 

Homologous recombination thus serves at least three identifiable functions (1) it contributes to the repair of several types of DNA damage (2) it provides, in eukaryotic cells, a transient physical link between chromatids that promotes the orderly segregation of chromosomes at the first meiotic cell division and (3) it enhances genetic diversity in a population. 

Many chromosomal alterations can be detected in plants,149 and, in addition to studies of mitotic cells, methods using microsporocytes (i.e., pollen mother cells) have permitted the study of meiotic cells.263 Although basic research in plant cytogenetics continues, cytogenetic tests in plants have been replaced to some extent in genetic toxicology by mammalian cell-culture tests and tests in whole mammals. 

Grant (1964) and Jordan and co-workers (1966) reported on other aberrative effects on nonphotosynthetic tissues, such as growth inhibition and abnormal meiotic cell formation. 

Hawley, R. S., Friend, S. H. (1996) Strange bedfellows in even stranger places The role of ATM in meiotic cells, lymphocytes, tumors and its functional links to p53. Genes Dev. 10 2383. 

GermOnline http //www.germonline.org/ GE in mitotic and meiotic cell cycle... 

Grasshoppers injected intra-abdominally with relatively high concentrations of soluble copper showed a 1.6% frequency of chromosomal anomalies in meiotic cells of testes 24 h after injection however, no control data were presented. Copper-induced DNA strand breaks in rats (Rattus sp.) and chromosomal aberrations and sperm abnormalities in mice (Mus sp.) suggest that copper is a potential human mutagen. Copper salts affect chromosomes in vitro in the presence of hydrogen peroxide and ascorbic acid and can also increase the frequency of noncomplementary nucleotides in... 

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