Mapping chromosomal homologies between humans and two langurs (Semnopithecus francoisi and S-Phayrei) by chromosome painting

Chromosomal homologies were established between human and two Chinese langu rs (Semnopithecus francoisi, 2n=44, and S. phayrei, 2n=44) by chromosome pa inting with chromosome-specific DNA probes of all human chromosomes except the Y. Both langur species showed identical hybridization patterns in addit ion to similar G-banding patterns. In total, 23 human chromosome-specific p robes detected 30 homologous chromosome segments in a haploid langur genome . Except for human chromosomes 1, 2, 6, 16 and 19 probes, which each gave s ignals on two non-homologous langur chromosomes respectively, all other pro bes each hybridized to a single chromosome. The results indicate a high deg ree of conservation of chromosomal synteny between human and these two Chin ese langurs. The human chromosome 2 probe painted the entire euchromatic re gions of langur chromosomes 14 and 19. Human chromosome 1 probe hybridized to three regions on langur autosomes, one region on langur chromosome 4 and two regions on langur chromosome 5. Human 19 probe hybridized on the same pattern to one region on chromosome 4 and to two regions on langur chromoso me 5, where it alternated with the human chromosome 1 probe. Human 6 and 16 probes both hybridized to one region on each of the two langur autosomes 1 5 and 18. Only two langur chromosomes (12 and 21) were each labelled by pro bes specific for two whole human chromosomes (14 and 15 and 21 and 22 respe ctively). Comparison of the hybridization patterns of human painting probes on these two langurs with the data on other Old World primates suggests th at reciprocal and Robertsonian translocations as will as inversions could h ave occurred since the divergance of human and the langurs from a common an cestor. This comparison also indicates that Asian colobines are karyotypica lly more closely related to each other that to African colobines.