Chromosomal localization of the 18S-28S and 5S rRNA genes and (TTAGGG)n sequences of butterfly lizards (Leiolepis belliana belliana and Leiolepis boehmei, Agamidae, Squamata)

Abstract

Chromosomal mapping of the butterfly lizards Leiolepis belliana belliana and L. boehmei was done using the 18S-28S and 5S rRNA genes and telomeric (TTAGGG)n sequences. The karyotype of L. b. belliana was 2n = 36, whereas that of L. boehmei was 2n = 34. The 18S-28S rRNA genes were located at the secondary constriction of the long arm of chromosome 1, while the 5S rRNA genes were found in the pericentromeric region of chromosome 6 in both species. Hybridization signals for the (TTAGGG)n sequence were observed at the telomeric ends of all chromosomes, as well as interstitially at the same position as the 18S-28S rRNA genes in L. boehmei. This finding suggests that in L. boehmei telomere-to-telomere fusion probably occurred between chromosome 1 and a microchromosome where the 18S-28S rRNA genes were located or, alternatively, at the secondary constriction of chromosome 1. The absence of telomeric sequence signals in chromosome 1 of L. b. belliana suggested that its chromosomes may have only a few copies of the (TTAGGG)n sequence or that there may have been a gradual loss of the repeat sequences during chromosomal evolution.

Cytogenetic analyses of five amazon lizard species of the subfamilies Teiinae and Tupinambinae and review of karyotyped diversity the family Teiidae

“…In Aspidoscelis marmorata (Baird & Girard, 1852), the same pattern was located in a macrochromosome pair (Porter et al 1991). Furthermore, it was possible to observe a size heteromorphism of the sites between the homologue chromosomes in the four analyzed species, a fact also described for other lizard species (O’Meally et al 2009, Srikunath et al 2009b, Srikunath et al 2011). Such a size heteromorphism is likely associated with unequal crossing-over mechanisms, rearrangements such as transpositions, deletions and/or duplications or variations in the number of rDNA copies present in such regions that would entail some changes in ribosomal sites (Gross et al 2010, Ribeiro et al 2008).…”

Physical Mapping and Refinement of the Painted Turtle Genome (Chrysemys picta) Inform Amniote Genome Evolution and Challenge Turtle-Bird Chromosomal Conservation

“…The absence of interstitial telomeric sequences in CPI corresponds with previous reports in other turtles which also lack them (e.g., Trachemys dorbigni and Chelonoidis donosobarrosi [ Martinez et al 2009 ]), as well as tuatara ( O’Meally et al 2009 ). However, these data contrast with lizards where they are present, for example, in microchromosomes in Pogona vitticeps ( Young et al 2013 ), macrochromosomes in Iberolacerta monticola ( Rojo et al 2014 ) or both in Leiolepis lizards ( Srikulnath et al 2011 ). However, additional data on the chromosomal location of telomeric sequences in a larger subset of turtle taxa are needed to test whether such contrasting patterns among these major reptilian lineages are generalizable.…”

Telomeres in Fishes

“…In the Russian sturgeon (Acipenser gueldenstaedtii) and in the lake sturgeon (A. fulvescens) , 2 entire microchromosomes showed bright fluorescence signals derived from the telomeric probe [Fontana et al, 1998[Fontana et al, , 2004. Similar distribution patterns of the hybridization signals have been described in some of the bird and reptile microchromosomes [Nanda et al, 2002;Srikulnath et al, 2011]. To intersperse with the entire microchromosomes, telomeric DNA sequences must have undergone extensive amplification processes extending telomeric arrays to an exceptional length ranging from 40 kb to 2 Mb or even longer [Delany et al, 2000].…”