The Homology and Relationship of Human (Homo sapiens) Chromosomes 1, 19 and Dusky Langur (Trachypithacus obscurus) Chromosomes 6, 8 Demonstrated with Chromosome Painting

Abstract

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 First Report on Standardized Karyotype and Idiogram of Indochinese Silvered Langur, <i>Trachypithecus germaini germaini</i> (Primates, Colobinae) in Thailand

“…Our study is in contrast to Sangpakdee et al (2008) and Tanomtong et al (2012), which found heteromorphic NOR of dusky langur (T. obscurus) on pair 19 and 17, respectively. In addition, Nie et al (1998) found heteromorphic NOR of Phayre s langur (T. phayrei) and Francois langur (T. francoisi) on pair 21.…”

“…This result compares with other langurs in Thailand as P. phayrei has metacentic, submetacentric, and acrocentric autosomes equal to 22-16-4 and 22-18-2 as reported by Chen et al (1981) and Nie et al (1998), respectively. The other langur species in Thailand, P. obscurus, has metacentic, submetacentric, and acrocentric autosomes equal to 26-12-2, 28-12-2, 22-18-2 and 12-16-4 as reported by Chiarelli (1963), Ponsa et al (1983), Sangpakdee et al (2008) and Tanomtong et al (2012), respectively. In addition, the comparative of other langur cytogenetic data on this study and previous studies are shown in Table 2.…”

“…The sex chromosome of other true langurs in previous reports of T. obscures, T. cristatus and T. entrellus were submetacentirc chromosomes too as reported by Ushijima et al (1964), Hsu and Benirschke (1971), Ponsa et al (1983) and Tanomtong et al (2012). However, some reports showed that the true langur X chromosomes presented metacentric and metacentric chromosome, and the shape of Y chromosomes demonstrated metacentric, submetacentric, and acrocentric chromosomes (Chu and Bender 1961, Buettner-Janusch 1966, Chiarelli 1963, Chen et al 1981, Bigoni et al 1997a, Nie et al 1998, Sangpakdee et al 2008.…”

“…With regard to the chromosome characteristics of other langurs in the subfamily Colobinae in Thailand, T. pharei (2n=44, NF=88; Chen et al 1981, Nie et al 1998) andT. obcurus (2n=44, NF=88;Chiarelli 1963, Hsu and Benirschke 1971, Sangpakdee et al 2008, all of them have the same 2n of 44 and NF of 88. The Indochinese silvered langur autosomes comprises 6 large metacentric, 10 large submetacentric, 2 large acrocentric, 6 medium metacentric, 14 medium submetacentric, 2 small submetacentric, and 2 small acrocentric chromosomes (Table 1).…”

The First Karyological Study and Natural NOR Polymorphism in Banded Langur, <i>Presbytis femoralis</i> (Primate, Colobinae)

“…This result agrees with the chromosome characteristics of others in the subfamily Colobinae in Thailand. T. cristatus (Hsu and Benirschke 1970, Ponsà et al 1983, Bigoni et al 1997a, T. phayrei (Nie et al 1998), and T. obscures (Chiarelli 1963, Hsu and Benirschke 1971, Sangpakdee et al 2008 all have the same chromosome number of 2n = 44 and most have NF = 88. In previous studies, the diploid number of both African (genus Colobus) and Asian (genus Presbytis) colobines was found to be 2n = 44 and most have NF = 88 (Chiarelli 1963, Ushima et al 1964.…”