Biderre C, Duffieux F, Peyretaillade E, Glaser P, Peyret P, Danchin A, Pagès M, Méténier G, Vivarès C P
Laboratoire de Protistologie Moléculaire et Cellulaire des Parasites Opportunistes, URA CNRS 1944, Université Blaise Pascal, Aubière, France.
Gene. 1997 May 20;191(1):39-45. doi: 10.1016/s0378-1119(97)00026-7.
The molecular karyotype of a murine isolate of Encephalitozoon cuniculi, a microsporidian with a wide range of mammalian hosts, comprises eleven chromosomes ranging in size between 217 and 315 kb. To determine specific chromosomal markers, a partial genomic library was constructed and cloned DNA fragments were hybridized to chromosomal bands separated by pulsed-field gel electrophoresis. Most probes were assigned to single chromosomes, indicating prevalence of low-copy number nucleotide sequences within the very small genome of E. cuniculi (2.9 Mb). A few probes were shown to hybridize to all chromosomes. These repetitive DNA fragments corresponded to either rRNA genes or some non-coding regions whose sequences were characterized by short micro- and minisatellites. The chromosomal locations of beta-tubulin genes and six newly identified protein-encoding genes were determined. Genes encoding dihydrofolate reductase, thymidylate synthase, serine hydroxymethyl transferase, a cdc2 kinase-like protein and helicase ERCC6-like protein were each located on a single chromosome whereas genes for both beta-tubulin and aminopeptidase were on two different chromosomes. The mapping will serve as a reference for further analysis of intraspecific karyotype polymorphism in different isolates from different host species.
兔脑炎微孢子虫是一种可寄生于多种哺乳动物的微孢子虫，其一个鼠源分离株的分子核型由11条染色体组成，大小在217至315 kb之间。为了确定特定的染色体标记，构建了一个部分基因组文库，并将克隆的DNA片段与通过脉冲场凝胶电泳分离的染色体条带进行杂交。大多数探针被定位到单条染色体上，这表明在兔脑炎微孢子虫非常小的基因组（2.9 Mb）中低拷贝数核苷酸序列占主导。有少数探针显示能与所有染色体杂交。这些重复DNA片段对应于rRNA基因或一些非编码区域，其序列的特征是存在短微卫星和小卫星。确定了β-微管蛋白基因和六个新鉴定的蛋白质编码基因的染色体定位。编码二氢叶酸还原酶、胸苷酸合成酶、丝氨酸羟甲基转移酶、一种cdc2激酶样蛋白和螺旋酶ERCC6样蛋白的基因各自位于一条单染色体上，而β-微管蛋白和氨肽酶的基因则位于两条不同的染色体上。该图谱将为进一步分析来自不同宿主物种的不同分离株的种内核型多态性提供参考。
