薄片牡蛎的核型及18S-28S核糖体rRNA基因的染色体定位

以薄片牡蛎(Dendostrea folium)成体鳃组织为材料制备有丝分裂中期染色体标本,对其染色体核型进行了分析,并运用荧光原位杂交技术(FISH)将18S-28S核糖体RNA基因定位于中期染色体上。FISH探针是通过PCR扩增介于18S-28S rRNA基因之间的ITS和5.8S rRNA基因序列,并在PCR扩增过程中掺入了Biotin-11-dUTP进行生物素标记。结果显示,薄片牡蛎的单倍染色体数目为n=10,全部为中部着丝粒染色体。与大多数已知巨蛎属牡蛎的染色体核型相似。ITS探针在薄片牡蛎中期分裂体相上产生两簇FISH信号,分别杂交于2号染色体短臂的近端粒区域。本研究首次报道了薄片牡蛎的中期染色体核型以及18S-28S核糖体RNA基因在染色体上的定位。

Karyotypes and Chromosomal Mapping of Major Ribosomal rRNA Genes in the Leaf Oyster (Dendostrea folium)

Karyotype and chromosomal location of the major ribosomal RNA genes were studied in the leaf oyster (Dendostrea folium) using fluorescence in situ hybridization (FISH).Metaphase chromosomes were obtained from gill tissue of adult oysters.Probes were prepared by PCR amplification from the internal transcribed spacers (ITS,containing the 5.8S rRNA genes) between the 18S and 28S ribosomal RNA genes,and labeled by PCR incorporation of Biotin-11-dUTP.The results showed that the leaf oyster (D.folium) had a haploid number of 10 chromosomes with a karyotype of ten metacentric chromosomes (10 M),which was similar to most species in genus Crassostrea.FISH with the ITS probes generated two signals per metaphase,which were hybridized to the telomere regions of the short arms of chromosome 2.This study is the first report of karyotype and chromosomal assignment of the major RNA genes in D.folium.