Chromosome number reduction accompanied by extensive heterochromatin addition in the bat <i>Glauconycteris beatrix</i> (Mammalia; Chiroptera, Vespertilionidae)

Abstract

The presumed ancestral karyotype of the bat family Vespertilionidae consists of 44 chromosomes with a fundamental number of autosomal arms (FNa) of 50. Previously, only two of the roughly 350 vespertilionid species have been reported with 2n lower than 26. In this paper we report the 2n = 22 karyotype of the African vespertilionid Glauconycteris beatrix which shows an X-autosome translocation and extended, paracentromeric, chromomycin-A3-positive heterochromatin.

Demonstration of 5-Methylcytosine-Rich DNA Sequences in Chiroptera

“…The chromosome complements determined in the 5 bat species are in agreement with previous cytogenetic studies on Glauconycteris , Pipistrellus , Neoromicia , and Rhinolophus [Rautenbach et al, 1993;Volleth et al, 2001Volleth et al, , 2013Kearney et al, 2002;Eick et al, 2007;Volleth and Heller, 2007;Koubínová et al, 2013]. G. beatrix is a bat with a very remarkable karyotype.…”

“…Approximately 30-50% of the chromosome lengths consist of such C-band positive material. As shown by Volleth and Heller [2007], all these C-bands label very brightly after staining with the GC base pair-specific fluorochrome chromomycin A 3 which clearly indicates that the highly repetitive DNA sequences in the genome of G. beatrix are GC-rich [Schweizer, 1976]. In addition to the very large centromeric and pericentromeric heterochromatin blocks, very faint interstitially located C-bands can be discerned in the long arms of some chromosomes ( Fig.…”

“…The only other species of the genus with a known karyotype is G. variegata in which 2n = 18 has been determined in both sexes [Rautenbach et al, 1993]. A previous cytogenetic analysis of the same female specimen of G. beatrix as described in the present study was performed in detail by Volleth and Heller [2007]. By means of comparative chromosome painting with DOP-PCR amplified flow-sorted chromosomes of the bat Myotis myotis [Ao et al, 2006], they demonstrated that in G. beatrix an X-autosome translocation with a chromosome homologous to Myotis chromosome 18 or 19 has occurred.…”

“…For the identification of this species and further details, see Heller et al [1994] and Volleth and Heller [2007].…”

Karyotype Evolution in the Horseshoe Bat <b><i>Rhinolophus sedulus</i></b> by Whole-Arm Reciprocal Translocation (WART)

“…In contrast, the heterochromatin of the X chromosome, although also being CMA-positive, showed a moderate fluorescence with quinacrine and DAPI. Compared to other Rhinolophidae species, the karyotype of RSE thus contains quite a large amount of CBG-positive heterochromatin and represents a further example in Chiroptera where the reduction of the diploid number is accompanied by acquisition of heterochromatin [see also Volleth and Heller, 2007].…”