Structural organization and functional analysis of centromeric DNA in the fission yeast Schizosaccharomyces pombe

Construction of functional artificial minichromosomes in the fission yeast Schizosaccharomyces pombe

The centromere DNAs from chromosomes I and III of Schizosaccharomyces pombe have been cloned in an artificial chromosome vector in both budding and fission yeasts. In S. pombe, synthetic linear and circular minichromosomes containing an intact centromere are stable mitotically and behave as independent genetic linkage groups that segregate properly through meiosis. These experiments present a general strategy for the isolation of centromeres from other organisms.

Development of large DNA methods for plants: molecular cloning of large segments of Arabidopsis and carrot DNA into yeast

Procedures for the preparation, analysis and cloning of large DNA molecules from two different plant species are described. Arabidopsis and carrot protoplasts were used for the preparation of large DNA molecules in agarose "plugs" or in solution. Pulsed-field gel electrophoresis (PFGE) analysis of large plant DNA preparations using a contour-clamped homogeneous field (CHEF) apparatus indicated that the size of the DNA was at least 12 Mb. Large DNA preparations were shown to be useful for restriction enzyme analysis of the Arabidopsis genome using both frequent and infrequent cutting enzymes and for the molecular cloning of large segments of DNA into yeast using artificial chromosome (YAC) vectors. PFGE and blot hybridization analysis of Arabidopsis and carrot DNA-containing YACs indicated that both unique and highly repeated DNA sequences were represented in these libraries.

Lysine biosynthesis pathway and biochemical blocks of lysine auxotrophs of Schizosaccharomyces pombe

The alpha-aminoadipate (AA) pathway for the biosynthesis of lysine was investigated in the wild type and in lysine auxotrophs of the fission yeast Schizosaccharomyces pombe. Of the eight enzyme activities of the AA pathway that have been examined so far, six were present in the extract of wild-type S. pombe cells. Growth response to AA and accumulation studies indicated that three lysine auxotrophs, the lys2-97, lys4-95, and lys8-1 strains, were blocked before the AA step and that four lysine auxotrophs, the lys1-131, lys3-37, lys6-3, and lys7-2 strains, were blocked after the AA step. Among the mutants investigated, the lys2-97 mutant exhibited an enzyme lesion at the cis-homoaconitate hydratase step, the lys1-131 and lys7-2 mutants exhibited lesions at the AA reductase step, and lys3-37 exhibited a lesion at the saccharopine dehydrogenase step. These results demonstrated the basic similarity of the AA pathway in S. pombe and Saccharomyces cerevisiae.