Possible interspecific origin of the B chromosome of Hypsiboas albopunctatus (Spix, 1824) (Anura, Hylidae), revealed by microdissection, chromosome painting, and reverse hybridisation

Abstract

The B chromosome in the hylid Hypsiboas albopunctatus (2n = 22 + B) is small, almost entirely composed of C-positive heterochromatin, and does not pair with any chromosome of the A complement. B probe, obtained by microdissection and DOP-PCR amplification, was used to search for homology between the B and regular chromosomes of H. albopunctatus and of the related species H. raniceps (Cope, 1862). Reverse hybridisation was also carried out in the investigation. The B probe exclusively painted the supernumerary, not hybridising any other chromosomes in H. albopunctatus, but all H. raniceps chromosomes showed small labelling signals. This result might be an indication that differences exist between the repetitive sequences of A and B chromosomes of H. albopunctatus, and that the chromosomes of H. raniceps and the heterochromatin of the B chromosome of H. albopunctatus are enriched with the same type of repetitive DNA. In meiotic preparations, the B labelled about 30% of scored spermatids, revealing a non-mendelian inheritance, and the painted B in micronucleus suggests that the supernumerary is eliminated from germ line cells. Although our results could suggest an interespecific origin of the B at first sight, further analysis on its repetitive sequences is still necessary. Nevertheless, the accumulation of repetitive sequences, detected in another species, even though closely related, remains an intriguing question.

Karyological analyses of Pseudhymenochirus merlini and Hymenochirus boettgeri provide new insights into the chromosome evolution in the anuran family Pipidae

“…On the other hand, up to nine B chromosomes have been found in anurans, namely in the hylid Gastrotheca espeletia Duellman andHillis, 1987, (Schmid et al, 2002), and cases of inter-population variability in the number of B chromosomes have been reported, for example in the hylid H. albopunctatus (Gruber et al, 2007(Gruber et al, , 2014Ferro et al, 2012). However, not excluding the possibility that the differences between our report and those by Scheel (1973) and Morescalchi (1981) may indicate a chromosome polymorphism in H. boettgeri or refer to different taxa, the karyotype settled up from regular elements is very interesting, particularly when compared with the chromosome complement of S. tropicalis.…”

“…However, the unpaired chromosome of H. boettgeri is larger than the regular chromosomes of the last two pairs. This aspect, though unusual, has been displayed by various taxa, for example in the Korean field mouse Apodemus peninsulae (Thomas, 1907) (Karamysheva et al, 2002;Trifonov et al, 2002), in the cyprinid fish Alburnus alburnus (Linnaeus, 1758) (Ziegler et al, 2003;Schmid et al, 2006) and, among anurans, in the hylid tree frog Hypsiboas albopunctatus (Spix, 1824) (Gruber et al, 2007(Gruber et al, , 2014Ferro et al, 2012). Thus, the unpaired element of two males of H. boettgeri can be regarded as a B chromosome, which suggests that at least one of their parents possessed and transmitted it.…”

Chromosome evolution in Cophomantini (Amphibia, Anura, Hylinae)

“…Gruber et al [ 76 ] performed chromosome painting on preparations of Boana albopunctata and B . raniceps using a chromosome probe obtained from the microdissection of a B chromosome of B .…”

“…albopunctata , observing signals on the B chromosome and, eventually, on pairs 3 and 8. Based on their results, Gruber et al [ 76 ] proposed an interspecific origin of the B chromosome of B . albopunctata , but without explaining a possible mechanism.…”

“…raniceps when using the B-probes. Nonetheless, the hypothesis proposed by Gruber et al [ 76 ] for an interspecific origin of the B chromosome in B . albopunctata is premature and needs further empirical support.…”