Heterochromatin heterogeneity and chromosome heteromorphism in Cerdocyon thous (Mammalia, Canidae)

Abstract

Few cytogenetic studies have been conducted on South American canids. Cerdocyon thous is a representative of the Canidae, living in the forests, open wooded areas and savannahs of South America. Compared to other canid species, C. thous has a large proportion of metacentric and submetacentric chromosomes as well as a large amount of constitutive heterochromatin, especially along the short arm of submetacentric chromosomes. In the present study, different chromosome banding methods were used to characterize the heterogeneous nature of the large heterochromatic segments and to propose an organizational model for this segment that occupies the entire short arm of most two-armed chromosomes. Furthermore, chromosome heteromorphism related to the short arm of large submetacentric chromosome corresponding to no. 3 in male and female karyotypes is described.<br>Os estudos citogenéticos em canídeos sul-americanos, de uma forma geral, são raros. Cerdocyon thous é um representante da família Canidae e habita florestas, matas abertas e savanas da américa do Sul. O seu cariótipo é formado por uma grande proporção de cromossomos metacêntricos e submetacêntricos quando comparado com outras espécies desta família e possui também uma grande quantidade de heterocromatina constitutiva, especialmente ao longo do braço curto dos cromossomos submetacêntricos. No presente estudo, diferentes métodos de bandamentos cromossômicos permitiram verificar o caráter heterogêneo dos grandes segmentos heterocromáticos e a proposição de um modelo de organização deste segmento que ocupa todo o braço curto da maioria dos cromossomos de dois braços. Além disso, é descrito um heteromorfismo cromossômico relacionado ao braço curto de um grande cromossomo submetacêntrico, equivalente ao no. 3 do cariótipo de animais de ambos os sexos

A comparison of heterochromatic regions in three species of neotropical canids

“…The three studied species have wide geographic distributions and the data shown here represent the most austral cytogenetic reports consistent with the previously published karyotypes (Brum-Zorrilla and Langguth, 1980;Hatanaka and Galetti Jr, 1999;Hatanaka et al, 1998;Nash et al, 2001;Pieńkowska-Schelling et al, 2008;Wayne et al, 1987). The 2n= 74, NF= 76 chromosome complement is highly conserved in most endemic Neotropical species with the exception of C. brachyurus that presents 2n= 76, and C. thous showing a large proportion of bi-armed autosomes.…”

“…3). Hatanaka et al, (1998) Other examples of chromosomal polymorphisms in canids have been described. In Vulpes lagopus (Linnaeus, 1758) variations of the diploid number due to a Robertsonian translocation produce 2n= 48, 49 and 50 individuals.…”

Occurrence of multiple nucleolus organizer regions and intraspecific karyotype variation in Scaptotrigona xanthotricha Moure (Hymenoptera, Meliponini)

“…Differential deletion, translocation, unequal crossover, and heterochromatin tandem growth have been suggested as possible causes of heterochromatin heteromorphisms (John, 1988;Hatanaka et al, 1998). According to Eichler and Sankoff (2003), these repetitive segments are hot spots for the occurrence of chromosomal rearrangements.…”

Chromosome Banding of Chrysocyon brachyurus (Mammali, Canidae).

“…The situation is quite similar to that observed in C. familiaris (Pathak and WursterHill 1977, Pathak et al 1982, Stone et al 1991 and some other carnivorous species (Pathak and Wurster-Hill 1977). In contrast, the heterochromatin has been reported much more abundant in the karyotype of Alopex lagopus (Yoshida et al 1983, Makinem et al 1985, Mayr et al 1986, among others) and Cerdocyon thous (Wayne et al 1987, Hatanaka et al 1998). An intercalar C positive band observed in the chromosome pair 14 of C. brachyurus, was not reported thus far in the karyotype of other canids.…”

“…Thus, the chromosome evolution of Canidae produced an extensive diversity of karyotypes mainly associated with chromosome fissions and fusions (Yoshida et al 1983, Switonski andGustaysson 1991, among others), although other types of chromosome rearrangements, such as heterochromatinization (Yoshida et al 1983, Hatanaka et al 1998) may have also played an important role in the karyotypic evolution of this family. Renovaveis) for permit n° 315/95 granted for the collection of material used in the present study .…”