Buroker N E, Magenis R E, Weliky K, Bruns G, Litt M
Hum Genet. 1986 Jan;72(1):86-94. doi: 10.1007/BF00278825.
Human gene mapping would be greatly facilitated if marker loci with sufficient polymorphism information content were generally available. As a source of such markers, we have used cosmids from a human genomic library. We have used a rapid method for screening random cosmids to identify those homologous to genomic regions especially rich in restriction fragment length polymorphisms (Litt and White 1985). This method allows whole cosmids to be used as probes against Southern transfers of genomic DNA; regions of cosmid probes homologous to repeated genomic sequences are rendered unable to anneal with Southern transfers by prehybridization of the probes with a vast excess of non-radioactive genomic DNA. From one cosmid (C1-11) identified by this procedure, we have isolated four single-copy probes, each of which identifies a polymorphic locus. Despite the existence of some linkage disequilibrium in this system, the polymorphism information content was computed as 0.73. Using a somatic cell hybrid mapping panel, we have mapped probes from cosmid 1-11 to human chromosome 12q. Additionally, in situ hybridization of the whole cosmid to metaphase spreads allowed more precise assignment of the locus to the region 12cen----q13. The locus revealed by probes from cosmid 1-11 has been designated D12S6.
如果能普遍获得具有足够多态性信息含量的标记位点，人类基因图谱绘制将得到极大促进。作为此类标记的一个来源，我们使用了来自人类基因组文库的黏粒。我们采用了一种快速筛选随机黏粒的方法，以鉴定那些与基因组区域同源、特别是富含限制性片段长度多态性的区域（Litt和White，1985年）。这种方法允许将完整的黏粒用作针对基因组DNA Southern转移的探针；通过用大量过量的非放射性基因组DNA对探针进行预杂交，使黏粒探针中与重复基因组序列同源的区域无法与Southern转移物退火。通过这一程序鉴定出一个黏粒（C1 - 11），我们从中分离出四个单拷贝探针，每个探针都鉴定出一个多态性位点。尽管该系统中存在一些连锁不平衡，但计算得出的多态性信息含量为0.73。利用体细胞杂种定位板，我们已将来自黏粒1 - 11的探针定位到人类染色体12q。此外，将完整黏粒与中期染色体铺展进行原位杂交，可将该位点更精确地定位到12cen----q13区域。由黏粒1 - 11的探针揭示的位点已被命名为D12S6。
