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SummaryChromosomal relationship between humans and dusky langurs (Trachypithecus obscurus, 2nϭ44) was established by chromosome painting using chromosome specific DNA probes of the human chromosome 1 and 19 which each gave hybridization signals on two non-homologous dusky langur chromosomes. The results show that the human chromosome 1 and 19 probes hybridized to three regions of dusky langur on the autosomes 6 and 8. The human chromosome 1 probe hybridized to one region on the dusky langur chromosome 6 and two regions on the dusky langur chromosome 8, where the human chromosome 19 probe hybridized with the same pattern but on different regions. Hybridization patterns of human painting probes on dusky langur, when compared with the data of other species in the same genus suggest that the alternating hybridization pattern of the conserved segments homologous to human chromosomes 1 and 19 on dusky langur chromosomes 6 and 8 is the result of the translocation followed by the pericentric inversion. Moreover, the present research also indicates that the dusky langur's chromosomes 6 and 8 have the same hybridization patterns as other Asian colobines. Key words Trachypithecus obscurus, Chromosome painting, Reciprocal translocations.The dusky langur (Trachypithecus obscurus) is also called the dusky leaf monkey belongs to the family Cercopithecidae, subfamily Colobinae. There are three groups of colobine monkeys: the colobus monkeys of Africa, the langurs and the odd-nosed monkeys of Asia. T. obscurus is a species of Asian langurs distributed throughout South-east Asia. However, it can be found only in the southern part of Thailand. The classification and taxonomy of colobines has not been yet settled and is subject to continued revisions (Napier and Napier 1967, 1985, Groves 1970, Oates et al. 1984, Vogel and Winkler 1990. For instance, there is no consensus even on the number of genera and species. The dusky langur is either classified in the genus Trachypithecus (Oates et al. 1984) or the genus Presbytis (Napier and Napier 1985). The scheme of Oates et al. (1984) was used as the classification system which put dusky langur into the genus Trachypithecus.In the previous studies using the classical staining, the diploid numbers of both African (genus Colobus) and Asian (genus Presbytis) colobines were demonstrated that they are to be 2nϭ44 (Chiarelli 1963, Ushima et al. 1964. All chromosomes can be divided into two groups; the metacentric and the submetacentric according to their centromeric index, with the exceptions that the Asian langurs have a pair of small acrocentric chromosomes while the African colobines have

The objectives of this study were to explore cytogenetic variation and the role of chromosomal change on local adaptation and genetic differentiation of Chironomus circumdatus Kieffer from Thailand. A total of 1,505 larvae from 24 populations were examined cytologically. Twelve chromosomal inversions were found and most of these (9 of 12) were rare inversions. All populations were in Hardy-Weinberg equilibrium. Significant association (P < 0.001) between the A2 and B5 inversions was detected in one population. Population genetic structure analysis indicated significant genetic differentiation between populations (F (ST) = 0.037, P < 0.001). Geographic distance was the principal factor limiting gene flow between populations. Nei's modified genetic distance (D (A)) between populations ranged from 0.001 to 0.011 with an average of 0.003. An UPGMA population phenogram depicting relationship between populations based on D (A) values revealed three groups of populations, group I, II and III each characterized by different inversions/inversion frequencies. Significant correlation of inversion C3 and water temperature suggested that this inversion might have a role to play on adaptation to high temperature habitat. However, if detection of significant population subdivision and relationship between genetic and geographic distance are taken into account, relationship between C3 and water temperature will also be due to the effect of migration/drift alone without the effect of selection.

SummaryWe report the first cytogenetic comparison of four grouper genera from Thailand. Kidney cell samples were taken from the blueline hind (Cephalopholis formosa), humpback grouper (Cromileptes altivelis), orange-spotted grouper (Epinephelus coioides), and leopard coralgrouper (Plectropomus leopardus). The mitotic chromosome samples were prepared directly from the kidney cells. Conventional and Ag-NOR staining techniques were applied to stain the chromosomes. The results showed that diploid chromosome numbers of Ce. formosa, Cr. altivelis, E. coioides, and P. leopardus were 2n=48 for all species, and the fundamental numbers (NF) were 52, 52, 50, and 48, respectively. The presence of metacentric, submetacentric, acrocentric, and telocentric chromosomes were 2-0-2-44, 0-2-2-44, 0-0-2-46, and 0-0-0-48, respectively. After the Ag-NOR banding technique, one pair of nucleolar organizer regions (NORs) was observed on the short arm telomeric region of