Molecular organization of the D-Qa region of t-haplotypes suggests that recombination is an important mechanism for generating genetic diversity of the major histocompatibility complex.
We have determined the molecular maps of the H-2D and Qa regions of the t-complex haplotypes t12 and tw5 by chromosomal walking. Analysis with class I probes and other probes unique to the H-2D:Qa subregion indicates that the class I gene organization of t12 is: D1-D2-Q1-Q2-Q3-Qx-Q4-Q5-Q10, while that of tw5 is: D1-D2-Q1-Q2-Q4-Q5-Q10. Thus, the absence of the Q6-Q9 genes suggested previously in t-haplotypes was confirmed. A comparison of the molecular maps of the t12 and tw5 chromosomes revealed an extremely mosaic pattern of diversity: The regions between D1 and D2, and between Q4 and Q10, are very similar in both chromosomes. However, their Q1 to Q3 regions are strikingly different. Further comparisons of wild-type chromosomes and additional t-haplotypes by molecular mapping and genomic Southern blot hybridization with probes to the Q1-Q3 region showed a high level of polymorphism among both wild-type chromosomes and among t-haplotypes. The characteristics of the polymorphisms suggest that recombination may play an important role in generating this genetic diversity. Furthermore, recombination between wild-type and t-haplotype chromosomes may be involved.
Uehara
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Department of Zoology, University of Texas, Austin 78712-1064.
Abe
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K
Flaherty
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Bennett
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D
Artzt
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D000818:Animals; D002874:Chromosome Mapping; D004251:DNA Transposable Elements / Q000235:genetics; D014644:Genetic Variation / Q000235:genetics*; D006183:H-2 Antigens / Q000235:genetics*; D006239:Haplotypes; D064532:Histocompatibility Antigen H-2D; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D051379:Mice / Q000235:genetics*; D008809:Mice, Inbred C3H; D012150:Polymorphism, Restriction Fragment Length; D011995:Recombination, Genetic / Q000235:genetics*
D004251:DNA Transposable Elements; D006183:H-2 Antigens; D064532:Histocompatibility Antigen H-2D; D015395:Histocompatibility Antigens Class I; C032907:Q surface antigens