Organisms Schizosaccharomyces pombe

The presence of the second active form of MIPS with a —65 kDa subunit indicated that the inositol requirement of the organism might be provided by the interplay of two different MIPS enzymes, probably by differential expression through time and space. The results indicate that the —65 kDa MIPS protein of Synechocystis might be coded by the ORF sill981, annotated as a putative acetolactate synthase (unpublished data from this laboratory). This gene also functionally complements the inositol auxotrophic yeast strain FY250 and Schizosaccharomyces pombe, a natural inositol auxotroph, and the expressed protein is immunoreactive to anti MIPS antibody. 

Finally, in addition to nucleotide excision repair and base excision repair, an alternative repair pathway exists to remove PyroPyr and (6 ) photoproducts in some organisms, including Schizosaccharomyces pombe. In this alternative pathway, an enzyme called UV dimer endonuclease cleaves DNA immediately 5 to the damaged lesion. The damage is then removed by a 5 to 3 exonuclease (26, 27). Additionally, AP endonucleases, like Nfo in E. coli and APEl in humans, have the ability to incise immediately 5 to nonbulky lesions caused by oxidative damage and initiate excision of the lesion by a 5 to 3 exonuclease (28). 

For much work on chemical activities of micro-organisms, it is important to use strains having known relevant genetical characteristics. Unfortunately, however, strains of only two species, Saccharomyces cerevisiae and Schizosaccharomyces pombe, have as yet been subjected to extensive genetic analysis, and neither species can utilize a wide range of exogenous sugars. 

Eukaryotic organisms Fungi Schizosaccharomyces pombe Forward mutation - - Loprieno 1981... 

Fig. 3. Alignment of partial PCNA amino acid sequences from various model eukaryotic organisms. Shaded residues match the consensus. Sc, Saccharomyces cerevisiae, Sp, Schizosaccharomyces pombe. Dm, Drosophila melanogaster, Ce, Caenorhabditis elegans At, Arabidopsis thaliana Mm, Mus musculus Hs, Homo sapiens. Lysl27 and Lysl64 residues of S. cerevisiae (indicated with arrows) are modified by SUMO only, or Ub and SUMO, respectively.

No events have been described which uniquely characterize the G1 phase. The G1 phase appears to perform two functions the temporary or permanent arrest of cell division in eukaryotes is normally achieved by cells maintaining themselves in the G1 phase of the cell cycle (Prescott, 1970) also the terminal part of the G1 must contain events concerned with the initiation of DNA synthesis. Certain organisms, for example, the fission yeast Schizosaccharomyces pombe (Bostock et al., 1966), the multinucleate slime mold Physarum polycephalum (Guttes et al., 1967), and Amoeba proteus (Ord, 1968), do not exhibit a G1 phase. A number of mammaUan cells appear to lack a G1... 

Most work in yeast genetics has been performed with two species, Sac-char omyces cerevisiae and Schizosaccharomyces pombe. For a detailed description of the respective life cycles, see Mortimer and Manney in Volume 1 of this series. It must be pointed out that both organisms can be cultivated as haploids and, in the case of Sacch. cerevisiae, in stable diploid forms as well. Since there are a great variety of yeasts of the Saccharomyces type which do not behave in this ideal way, all genetic experiments should be performed with strains currently used by yeast geneticists. Such strains are physiologically dioecious (see Esser 2) for definition of this term), whereas many strains isolated from nature are self-compatible and haploid cells fuse uncontrollably to form diploids. Typically, Saccharomyces strains... 

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