Becher D, Schulze S, Kasüske A, Stoll R, Wedler H, Oliver S G
Fachrichtung Biologie, Ernst-Mortiz-Arndt-Universität Greifswald, Germany.
Mol Gen Genet. 1995 Jun 10;247(5):591-602. doi: 10.1007/BF00290351.
The imperfect yeast Candida maltosa has an ill-defined genetic constitution; it is nominally diploid, but probably highly aneuploid, in nature. We report on polymorphisms specifically affecting those chromosomes which bear the cm-ADE1 gene. This gene encodes phosphoribosylaminoimidazole-succino-carboxamide synthetase, an enzyme in the adenine biosynthetic pathway. By electrophoretic karyotype analysis, three differently sized chromosomes were demonstrated to carry cm-ADE1; the size (but not the number) of these chromosomes was also found to vary, both between strains and during the mitotic growth of a single strain. Four different alleles of cm-ADE1 have been cloned and sequenced from one prototrophic strain. DNA sequence divergence between these different alleles is as high as 8%, with the greatest divergence being found in the upstream region. Mitotic recombination events that led to changes in the karyotype were followed by using cm-ADE1 DNA as an hybridization probe. A recombination hot-spot in the neighbourhood of the gene appears to be responsible for the instability of the chromosomes on which it residues.
不完全酵母麦芽糖假丝酵母的遗传构成尚不明确；它名义上是二倍体，但实际上可能是高度非整倍体。我们报道了特异性影响携带cm-ADE1基因的那些染色体的多态性。该基因编码磷酸核糖氨基咪唑-琥珀酰胺羧酰胺合成酶，这是腺嘌呤生物合成途径中的一种酶。通过电泳核型分析，证明有三条大小不同的染色体携带cm-ADE1；还发现这些染色体的大小（而非数量）在不同菌株之间以及单个菌株的有丝分裂生长过程中都会发生变化。从一个原养型菌株中克隆并测序了cm-ADE1的四个不同等位基因。这些不同等位基因之间的DNA序列差异高达8%，其中上游区域的差异最大。通过使用cm-ADE1 DNA作为杂交探针，追踪导致核型变化的有丝分裂重组事件。该基因附近的一个重组热点似乎是其所在染色体不稳定的原因。
