Murray Brent W., Nilsson Philomeen, Zaleska-Rutczynska Zofia, Sültmann Holger, Klein Jan
Max-Planck-Institut für Biologie, Abt. Immungenetik, Corrensstrasse 42, D-72076 Tübingen, Germany
Mar Biotechnol (NY). 2000 Sep;2(5):437-448. doi: 10.1007/pl00021683.
The haplochromine cichlid species flocks of the East African Great Lakes are one of the best examples of adaptive radiation. Analysis of genetic variation among these species provides valuable information on species relationships and timing of speciation events. Although the haplochromine cichlids generally display little genetic variation, the major histocompatibility complex (Mhc) genes have been found to be highly variable. A study of the linkage relationships of the Mhc class I A genes in the cichlid fish Oreochromis niloticus was therefore undertaken. Class I loci were identified, and their segregation in seven mothers and their haploid embryos was determined. In total, 56 class I A sequences were found among the seven families. A strong concordance of segregation was observed in five haplotypes among the embryos, indicating a close linkage of all loci. The number of loci per haplotype varied from 11 to 17, while the total number of distinct loci found among all families was 22. These findings show that all class I A loci are linked in a single genetic cluster in O. niloticus.
东非大湖的帚齿丽鱼科丽鱼物种群是适应性辐射的最佳例证之一。对这些物种间遗传变异的分析为物种关系及物种形成事件的时间提供了有价值的信息。尽管帚齿丽鱼科丽鱼通常显示出很少的遗传变异，但已发现主要组织相容性复合体（Mhc）基因具有高度变异性。因此，开展了一项关于丽鱼科鱼类尼罗罗非鱼中Mhc I类A基因连锁关系的研究。鉴定出了I类基因座，并确定了它们在七条母鱼及其单倍体胚胎中的分离情况。在这七个家系中总共发现了56个I类A序列。在胚胎中的五个单倍型中观察到了强烈的分离一致性，表明所有基因座紧密连锁。每个单倍型的基因座数量从11个到17个不等，而在所有家系中发现的不同基因座总数为22个。这些发现表明，在尼罗罗非鱼中所有I类A基因座都连锁在一个单一的基因簇中。
