三种龟类动物的细胞遗传研究

A CYTOGENETIC STUDY ON THREE SPECIES OF TURTLE

本文以外周血淋巴细胞为材料，首次报道马来闭壳龟和地龟的核型，G带，C带和Ag－NORs，以及平胸龟的G带和C带。发现平胸龟的核型与前人报道的有差异。研究结果表明：平胸龟2＝54（14M＋4ST＋ST＋28m），N．F＝72，7＋6＋14。A组No．6qper有一次缢痕．Ag－NOAs位于A组的Nb．7qter。其全部染色体的着丝粒区均显示阳性C带，并且A组的No．7整条异染色质化；马来闭壳龟Zn＝52（18M＋4ST＋6T＋24m），N．E＝74，9＋5＋12。Ag－NORs位于A组No．7qter．全部染色体的着丝粒区均有深染C带，C组的No．1整条异染色质化；地龟核型Zn＝52（16M＋4ST＋6T＋26m），N．F＝72，8＋5＋13，A组No．7pper有一次缢痕。Ag－NORs位于A组No．7qper，呈异态。全部染色体着丝粒区C带阳性，A组的No．1qter和Nb．2，7pqter呈现C带阳性．在三种龟的G带型中，仅马来闭壳龟A组No．8和B组No．2有时呈现同源染色体间异型，其余均可进行同源配对．本文还讨论了核型的演化机制。

The conventional karyotypes, G-bands, C-bands and Ag-NORs of three species of turtles have been studied. Platysternon megacephalum Gray has 2n =54(14M + 4ST + 8T + 28m), N. F. = 72, 7 + 6 + 14(Karyotypic formula). The No. 6 chromosome of group A has a secondary constriction (SC) in the q per. The Ag-NORs are on the No. 7 q ter of group A; Cuora amboinensis (Daudin) has 2n = 52(18M + 4ST+ 6T + 24m),N. F. = 74, 9 + 5 + 12. There are a pair of Ag-NORs in the No.7 q per of group A; Geoemyda spengleri Gmelin has 2n =52(16M + 4ST + 6T + 26m), N.F. = 72, 8 + 5 + 13. The No.7 p per of group A has a SC. The Ag-NORs with hereromorphic phenomenon located on the No.7 q per of group A.All of the centromeric regions of the chromosomes showed staining of C-positihve for these three species. Besides this, the telomeric C-bands was found at the No. 1 q ter of group A and the Nos.2,7 p q ter of group C in G. spengleri. The No.7 chromosome of group A of P. megacephalum and the No. 1 chromosome of group C of C. amboinensis showed whole staining of C-positive.The chromosomes of G-banded were analyzed. The results show that each homologous pair has its own special G-banded patterns, so is possible to be paired in the karyotype.