Lee C, Griffin D K, O'Brien P C, Yang F, Lin C C, Ferguson-Smith M A
Department of Pathology, University of Cambridge, England, UK.
Chromosoma. 1998 Mar;107(1):61-9. doi: 10.1007/s004120050281.
A comprehensive cytogenetic characterization of the unusally large reindeer (Rangifer tarandus) sex chromosomes is presented for the purpose of studying the evolution of these atypical gonosomes. Sex chromosome idiograms were constructed from G-banded and C-banded chromosomes to illustrate the relative amounts and locations of euchromatin and heterochromatin. Hybridization with a Mazama gouazoubira X whole-chromosome paint revealed that essentially all reindeer X-linked euchromatin and most reindeer Y-linked euchromatin is conserved interspecifically. Subsequently, painting probes were generated from flow-sorted reindeer X chromosomes, flow-sorted reindeer Y chromosomes, and from microdissections of specific gonosomal regions to establish specific segment-to-segment homologies between these gonosomes. In particular, one microdissection-generated paint demonstrated that certain constituent repetitive DNAs, found in C-band region Xq31, were also present in essentially all heterochromatin blocks of the Y chromosome. Microdissection-generated paints from other X-linked heterochromatin blocks revealed the presence of DNA sequences that lacked homologous sequences on the Y chromosomes and were more specific for their region of origin. These characteristics of the reindeer sex chromosomes are consistent with the notion that mammalian sex chromosomes were derived from homologous progenitor chromosome pairs and provide insights into the evolution of these atypical mammalian gonosomes.
为了研究这些非典型性染色体的进化，本文对异常大的驯鹿（Rangifer tarandus）性染色体进行了全面的细胞遗传学特征分析。通过G带和C带染色体构建了性染色体核型图，以说明常染色质和异染色质的相对含量和位置。与马萨马鹿（Mazama gouazoubira）X全染色体涂染探针杂交显示，基本上所有驯鹿X连锁常染色质和大多数驯鹿Y连锁常染色质在种间是保守的。随后，从流式分选的驯鹿X染色体、流式分选的驯鹿Y染色体以及特定性染色体区域的显微切割中生成涂染探针，以建立这些性染色体之间特定片段对片段的同源性。特别是，一种显微切割生成的涂染探针表明，在C带区域Xq31中发现的某些组成性重复DNA，也基本上存在于Y染色体的所有异染色质块中。来自其他X连锁异染色质块的显微切割生成的涂染探针显示，存在一些在Y染色体上缺乏同源序列且对其起源区域更具特异性的DNA序列。驯鹿性染色体的这些特征与哺乳动物性染色体源自同源祖染色体对的观点一致，并为这些非典型哺乳动物性染色体的进化提供了见解。
