Matsuda M, Matsuda C, Hamaguchi S, Sakaizumi M
Graduate School of Science and Technology, Faculty of Science, Niigata University, Ikarashi, Niigata (Japan).
Cytogenet Cell Genet. 1998;82(3-4):257-62. doi: 10.1159/000015113.
In the medaka, Oryzias latipes, which does not have cytologically recognizable sex chromosomes, the sex is genetically determined and the mechanism of sex determination (XX/XY) can be revealed by genetic crosses using a particular pigment gene. In a previous study, we isolated a sex-linked DNA marker (SL1) using the genomic differences between inbred strains of medaka. In the present paper, we further isolated another sex-linked clone (pHO5.110). The pHO5. 110-related sequences were tightly linked to sex in O. latipes. We designated the locus of the pHO5.110-related sequence on sex chromosomes of medaka as Sex-Linked 2 (SL2). Southern blot analyses suggested that the pHO5.110-related sequence was tandemly repetitive in the medaka genome. Using the clone as a probe for FISH analysis, strong hybridization signals were obtained in a couple of chromosomes that formed one of two large submetacentric chromosome pairs. The pHO5.110-related sequences were repetitive in the genomes of other species of Oryzias (O. curvinotus, O. luzonensis and O. mekongensis) that are karyologically related to O. latipes (all are members of the so-called biarmed group). By contrast, the sequences were not detected as repetitive in other Oryzias species. Hence, it is thought that pHO5.110-related sequences were amplified in the genome of a common ancestor of the biarmed group.
在青鳉（Oryzias latipes）中，没有细胞学上可识别的性染色体，其性别由基因决定，并且可以通过使用特定色素基因的遗传杂交来揭示性别决定机制（XX/XY）。在之前的一项研究中，我们利用青鳉近交系之间的基因组差异分离出了一个性连锁DNA标记（SL1）。在本文中，我们进一步分离出了另一个性连锁克隆（pHO5.110）。pHO5.110相关序列在青鳉中与性别紧密连锁。我们将青鳉性染色体上pHO5.110相关序列的位点命名为性连锁2（SL2）。Southern印迹分析表明，pHO5.110相关序列在青鳉基因组中是串联重复的。使用该克隆作为FISH分析的探针，在形成两个大的亚中着丝粒染色体对之一的一对染色体中获得了强烈的杂交信号。pHO5.110相关序列在与青鳉核型相关的其他青鳉属物种（弯月青鳉、吕宋青鳉和湄公河青鳉）的基因组中是重复的（它们都是所谓双臂组的成员）。相比之下，在其他青鳉属物种中未检测到这些序列是重复的。因此，认为pHO5.110相关序列在双臂组共同祖先的基因组中被扩增。
