Highly Species-Specific Centromeric Repetitive DNA Sequences in Lizards: Molecular Cytogenetic Characterization of a Novel Family of Satellite DNA Sequences Isolated from the Water Monitor Lizard (Varanus salvator macromaculatus, Platynota)

Abstract

Two novel repetitive DNA sequences, VSAREP1 and VSAREP2, were isolated from the water monitor lizard (Varanus salvator macromaculatus, Platynota) and characterized using molecular cytogenetics. The respective lengths and guanine-cytosine (GC) contents of the sequences were 190 bp and 57.5% for VSAREP1 and 185 bp and 59.7% for VSAREP2, and both elements were tandemly arrayed as satellite DNA in the genome. VSAREP1 and VSAREP2 were each located at the C-positive heterochromatin in the pericentromeric region of chromosome 2q, the centromeric region of chromosome 5, and 3 pairs of microchromosomes. This suggests that genomic compartmentalization between macro- and microchromosomes might not have occurred in the centromeric repetitive sequences of V. salvator macromaculatus. These 2 sequences did only hybridize to genomic DNA of V. salvator macromaculatus, but no signal was observed even for other squamate reptiles, including Varanus exanthematicus, which is a closely related species of V. salvator macromaculatus. These results suggest that these sequences were differentiated rapidly or were specifically amplified in the V. salvator macromaculatus genome.

Molecular cloning and characterization of satellite DNA sequences from constitutive heterochromatin of the habu snake (Protobothrops flavoviridis, Viperidae) and the Burmese python (Python bivittatus, Pythonidae)

“…To date, however, no microchromosome-specific centromeric repetitive sequences have been isolated in squamates. Although the karyotypes of snakes, monitor lizards, and scincid lizards have many microchromosomes, both PFL-MspI and PBIDdeI isolated in the present study, as well as the VSAREP sequence family from the water monitor lizard (V. salvator macromaculatus) and HinfI stDNA from the ocellated skink (C. ocellatus) (Chaiprasertsri et al 2013;Giovannotti et al 2013) are all localized to the centromeric regions of both macrochromosomes and microchromosomes. Thus, centromeric repetitive sequences appear to have evolved in a conc e r t e d m a n n e r a c r o s s m a c r o c h r o m o s o m e s a n d microchromosomes without chromosome size-correlated compartmentalization.…”

“…In squamate reptiles, stDNA have been isolated from lacertid lizards (Capriglione et al 1989(Capriglione et al , 1991(Capriglione et al , 1994(Capriglione et al , 1998Ciobanu et al 2004;Grechko et al 2005;Giovannotti et al 2014), scincid lizards (Giovannotti et al 2009(Giovannotti et al , 2013, a varanid lizard (Chaiprasertsri et al 2013), and a snake (Singh et al 1976). In most of these cases, the stDNA was localized to the heterochromatin, specifically in centromeric, pericentromeric, and/or telomeric regions.…”

“…These observations suggest a restricted homogenization of the centromeric repetitive sequences within microchromosomes in these species. In contrast, the water monitor lizard (Varanus salvator macromaculatus) and the ocellated skink (Chalcides ocellatus) have centromeric repetitive sequences that are shared in some macrochromosomes and microchromosomes (Chaiprasertsri et al 2013;Giovannotti et al 2013). Therefore, molecular cytogenetic characterization of the repetitive sequences in the heterochromatin of snakes should provide important information on the evolutionary changes in the genomic organization of macrochromosomes and microchromosomes in squamate reptiles.…”

First Description of the Karyotype and Sex Chromosomes in the Komodo Dragon <b><i>(Varanus komodoensis)</i></b>

“…It has the diploid chromosome number 2n = 40 and possesses ZZ/ZW sex chromosomes. In fact, the whole family appears to be very conservative in chromosome number, with also the number of macrochromosomes and microchromosomes being very stable in the whole group [King and King, 1975;Chaiprasertsri et al, 2013;Srikulnath et al, 2013;Matsubara et al, 2014]. Based on the modern phylogeny, the monospecific fam- ily Lanthanotidae is likely to be a sister group to Varanidae [Pyron et al, 2013], but as the karyotype has not yet been determined, we cannot reconstruct how far in the phylogeny this uniformity extends.…”

The Organization of Repetitive DNA in the Genomes of Amazonian Lizard Species in the Family Teiidae

“…Repetitive telomeric DNA and 5S and 18S rDNA as well as retroelements have been largely mapped by FISH in various species of vertebrates Terencio et al, 2012;Chaiprasertsri et al, 2013;Rojo et al, 2014;Pokorná et al, 2015]. Among these functional repetitive DNAs, the DNA of the 5S ribosomal multigene family consists of 120-bp coding sequences which are separated by a non-transcribed spacer (NTS) DNA of variable length.…”