Cytogenetic analysis of the tamaraw Bubalus mindorensis): a comparison of R-banded karyotype and chromosomal distribution of centromeric satellite DNAs, telomeric sequence, and 18S-28S rRNA genes with domestic water buffaloes

Abstract

The karyotype of the tamaraw (Bubalus mindorensis, 2n = 46) was investigated by RBG-banding technique and compared with those of the river and the swamp cytotypes of domestic water buffalo (B. bubalis). The tamaraw karyotype consisted of 6 submetacentric and 16 acrocentric autosome pairs (NAA = 56), and X and Y chromosomes. The RBG-banded karyotype of the three taxa had a high degree of homology, and the tamaraw karyotype could be explained by a Robertsonian translocation between chromosomes 7 and 15 and by a telomere-centromere tandem fusion between chromosomes 4p and 12 of the standardized river buffalo cytotype (2n = 50, NAA = 58). The buffalo satellite I and II DNAs were localized to the centromeric regions of all the tamaraw chromosomes. The biarmed chromosome 2 of the tamaraw resulting from the fusion between chromosomes 7 and 15 of the standard contained much larger amounts of the satellite I DNA than the other biarmed chromosomes, suggesting that this chromosome was formed by a relatively recent Robertsonian fusion. The (TTAGGG)n telomeric sequence was specifically localized to the telomeric region of all the buffalo chromosomes. The 18S + 28S rDNA was localized to the telomeric regions of the chromosomes 5p, 7, 19, 21, and 22 of the tamaraw and of their homologous chromosomes in the river and swamp buffalo cytotypes.

Phylogenetic position of the saola <i>(Pseudoryx nghetinhensis)</i> inferred from cytogenetic analysis of eleven species of Bovidae

“…8 c, d). The intensity of hybridization signals was constant and each chromosome generally exhibited four signals confirming the telomeric pattern previously found in most bovid species (Meyne et al, 1990;de la Seña et al, 1995;Tanaka et al, 2000).…”

“…However, Tanaka et al's interpretation is likely erroneous since the same chromosome was matched twiceonce as chromosome R6, and then as chromosome R12 of river buffalo; in the latter case it was presumably homologous to the tamaraw's chromosome 1q ( Fig. 3 in Tanaka et al, 2000). Similar errors occur elsewhere in their comparison and it seems that this disagreement results from a partial lack of correspondence in chromosome numbering using G-and R-banded chromosome nomenclature, and the mismatching of at least two chromosomal pairs in the Tanaka et al (2000) publication.…”

“…In our study one tandem translocation (BTA3;22;2) was identified in two species of eland and one (BTA7;5;28) in the swamp buffalo ( Bubalus bubalis ). It is noteworthy that chromosome 1 of the tamaraw ( B. mindorensis ) results from a tandem translocation involving Rb chromosome (BTA5;28; Tanaka et al, 2000) which is similarly present in the swamp buffalo, but which is fused with BTA11 in the former and BTA7 in the latter species. However, Tanaka et al's interpretation is likely erroneous since the same chromosome was matched twiceonce as chromosome R6, and then as chromosome R12 of river buffalo; in the latter case it was presumably homologous to the tamaraw's chromosome 1q ( Fig.…”

Mapping the distribution of the telomeric sequence (T₂AG₃)_n in rock wallabies, <i>Petrogale</i> (Marsupialia: Macropodidae), by fluorescence in situ hybridization

“…Previous studies have shown that the (T 2 AG 3 ) n sequence is retained during fusion events in some species (Lee et al, 1993;Thomsen et al, 1996;Vermeesch et al, 1996;Fagundes et al, 1997;Fagundes and Yonenaga-Yassuda, 1998), but not others (Schubert et al, 1992;Garagna et al, 1995;Nanda et al, 1995;Thomsen et al, 1996;Tanaka et al, 2000). For both the 6ˆ10 fusion of P. l. hacketti and the 9ˆ10 fusion of the West Kimberley race, (T 2 AG 3 ) n sequence signals were identified near the centromere, the presumed site of fusion (Fig.…”

Chromosome Evolution in Domestic Bovids as Revealed by Chromosome Banding and FISH-Mapping Techniques

“…In Bubalus mindorensis (tamaraw) (2n = 46, FN = 56) there are 6 biarmed chromosomes resulting from centric fusions, 5 of which are identical to the swamp buffalo, plus one additional translocation, the 4; 14 [Tanaka et al, 2000a]. Most likely, the mindorensis is a recent derivation from the swamp buffalo.…”