【摘要】 黑斑蛙染色体数目为2n=26。利用血细胞培养和骨髓制片及BrdU-Hoechst 33258-Giemsa技术研究表明,黑斑蛙的性别决定为XY型。其第9染色体可能是性染色体,该染色体长臂近中部SRR区可能是与性别决定有关的区域。该区域在雌性中是同步复制的;在雄性中是非同步复制的,一个比另一个更晚复制。这一复制异态开始于中S期,终止于晚S期。更多还原

【Abstract】 The time sequences of DNA replication in the chromosomes and C-banding pattern of 4 male and 6 female common frogs R. nigromaculata were studied by a modified BrdU-Hoechst33258-Giemsa technique, using the asynchronized lymphocytes cultivated in vitro and bone marrow preparations. It was found that there was a diploid chromosome complement of 26 in R. nigromaculata, the karyotype consisted of 5 pairs of large homologue in which the No. 4 pair was submedian, 4 pairs median, and 8 pairs of small ones in which 4 pairs were median and the rest submedian without terminal Gentries. Its total arm count was 52.Sex determination in B. nigromaculata was of the XX/XY type, chromosome pair No. 9 was probably the sex chromosome, in which certain distinct regions located in the long arm were late in replication in the karyotypes of all the observed individuals. We therefore called this region the sex related region (SKR). This region was replicated synchronously in the female animal but asynchronously in the male, i.e., one of two SRRs in the male was replicated later than the other.The replicative heteromorphism began from the middle S phase of the cells cycle and came to an end in the late S phase. Both the above-mentioned SRRs were with C-banding dark staining and no difference was seen between females and males. In this aspect no sex related heteromorphism between homologues could be found in the other chromosomes. However, whether this designated SRR is really related to the sex determination or not, awaits further investigation with sufficient materials.更多还原