黄姑鱼染色体识别与重复序列定位

黄姑鱼是我国重要的海水经济鱼类。然而,由于细胞遗传标记匮乏,黄姑鱼染色体仍然难以辨识。为了提高黄姑鱼染色体的配对识别水平,本研究利用荧光原位杂交(fluorescence in situ hybridization,FISH)、吉姆萨染色和荧光染色技术分析了黄姑鱼染色体的特征。以总DNA为探针进行基因组DNA荧光原位杂交(genomic fluorescence in situ hybridization,GISH),从而获得黄姑鱼染色体图谱,可使每对染色体呈现特定的荧光信号。依据GISH荧光信号分布模式,可以辨识黄姑鱼的24对染色体。18S r DNA FISH结果显示,18S r DNA只有一对信号,分布于1号染色体臂间,并与吉姆萨染色呈现的次缢痕、DAPI阴性带和DPI染色高亮区域同位。5S r DNA有一强一弱两对信号,信号强的一对分布于1号染色体着丝粒端,信号弱的一对分布于4号染色体的远端。端粒信号在所有染色体的端部显示,但个别染色体一端信号微弱。本研究结果丰富了黄姑鱼的细胞遗传标记,为解决黄姑鱼染色体辨识问题提供参考依据,也为进一步研究石首鱼科染色体进化提供了资料。

Chromosome mapping using genomic DNA and repetitive DNA sequences as probes for somatic chromosome identification in Nibea albiflora

Yellow croaker Nibea albiflora is a species of commercial important fish. However, chromosome identification is still difficult in yellow croaker for lack of cytogenetic markers. Hence, we analyzed the characteristics of chromosome in yellow croaker by using Giemsa staining, fluorescence staining, genomic in situ hybridization(GISH), and fluorescence in situ hybridization (FISH) with repetitive DNA sequences to assist chromosome identification. According to the distribution mode of fluorescent signal of self-GISH, 24 pairs of chromosomes could be distinguished and paired. FISH with 18S rDNA resulted in one pair of 18S rDNA signals distributing at the interstitial region of chromosome 1, which colocated with the secondary constriction after Giemesa staining, the negative band after DAPI staining, and the highlighted area after DPI staining. Whereas 5S rDNA FISH resulted in two pairs of signal with different intensity. The strong one was located on the centromere of chromosome 1, and the weak one was located on the distal position of chromosome 4. The signals of telomeric sequence were located on both termini of all chromosomes, although the signals of some chromosomes were weak. These results enriched the cytological genetic markers for chromosome identification in N. albiflora, and provided basic data for studying the chromosome evolution of Sciaenidae.