Chromosomal localization of satellite DNA sequences among 22 species of felids and canids (Carnivora)

Abstract

In situ hybridization was carried out using cloned satellite DNAs from the domestic cat and domestic dog as probes to metaphase chromosomes from 12 species of felids and 10 species of canids. Autoradiographic silver grains along metaphase chromosomes were counted and analyzed with regard to the mean number of grains per cell in each species, their chromosomal location, and their presence or absence on specific autosomes or sex chromosomes, where known. Among the felids and canids there was a 7.6- and 8.9-fold statistically significant difference, respectively, in the mean number of grains per cell between the species having the minimum and maximum values. Among the felids, most grains occurred on the telomeres of D- and E-group chromosomes, although departures from this general pattern also occurred. For example, the Asian golden cat and the Bornean bay cat showed substantial labeling at the centromeric region of chromosome Al, and a number of species showed some labeling at the short-arm telomeres of B-group chromosomes. Among the canids, about 90% of all grains were located at autosomal centromeres, and grains were absent from the sex chromosomes. Grains are usually distributed at chromosomal locations that stain C-band positive; however, certain C-band-positive regions without grains probably do not contain the particular satellites studied here.

A repeat DNA sequence from the Y chromosome in species of the genus Microtus

“…MSAT-160, a satellite DNA located on the centromeres of most autosomes of Microtus species, is also located on the X and Y chromosomes (Modi et al 2003). Particularly, this satellite is present in the centromere and heterochromatic block of the X chromosome in some species.…”

“…M. agrestis) (for a review, see Marchal et al 2003). MSAT-2750 is present only on the heterochromatic blocks of both X and Y chromosomes of M. chrotorrhinus , Modi et al 2003. MSAT-21 is present on the X and Y heterochromatic blocks of M. chrotorrhinus and M. rossiaemeridionalis, as well as in some autosomal centromeres in the latter species , Modi et al 2003.…”

“…Both cytogenetic and molecular analyses have demonstrated that the gonosomal constitutive heterochromatin in the genus Microtus is highly heterogeneous (Burgos et al 1988c, Modi et al 2003. In fact, several repeated DNA sequences located in the sex chromosomes have been described in this genus.…”

“…Furthermore, the sequences included and ampli¢ed in the gonosomal heterochromatin have probably been randomly selected in each species (Burgos et al 1990, Singh et al 2000, Modi et al 2003.…”

Highly repeated DNA sequences in three species of the genus Pteropus (Megachiroptera, Mammalia)

“…Two main kinds of highly repetitive sequences are known in mammalian genomes: interspersed DNA, in which the repeated DNA sequences are dispersed throughout the genome; and satellite DNA which is characterised by long tandem arrays and consistent association with constitutive heterochromatin (Singer, 1982). The localised repeats, or satellite DNAs, are typically found at C-band-positive regions of chromosomes, such as centromeres, telomeres and a portion of the Y chromosomes (Modi et al, 1988;Hamilton et al, 1990). The satellite DNAs, which are generally A-T rich, are organised in tandem arrays of repeat units and are highly variable with respect to the nucleotide sequence, the size of units, number of repeated units, and genome and chromosome organisation and localisation (Charlesworth et al, 1994).…”