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)

Abstract

Highly repetitive DNA sequences of the centromeric heterochromatin provide valuable molecular cytogenetic markers for the investigation of genomic compartmentalization in the macrochromosomes and microchromosomes of sauropsids. Here, the relationship between centromeric heterochromatin and karyotype evolution was examined using cloned repetitive DNA sequences from two snake species, the habu snake (Protobothrops flavoviridis, Crotalinae, Viperidae) and Burmese python (Python bivittatus, Pythonidae). Three satellite DNA (stDNA) families were isolated from the heterochromatin of these snakes: 168-bp PFL-MspI from P. flavoviridis and 196-bp PBI-DdeI and 174-bp PBI-MspI from P. bivittatus. The PFL-MspI and PBI-DdeI sequences were localized to the centromeric regions of most chromosomes in the respective species, suggesting that the two sequences were the major components of the centromeric heterochromatin in these organisms. The PBI-MspI sequence was localized to the pericentromeric region of four chromosome pairs. The PFL-MspI and the PBI-DdeI sequences were conserved only in the genome of closely related species, Gloydius blomhoffii (Crotalinae) and Python molurus, respectively, although their locations on the chromosomes were slightly different. In contrast, the PBI-MspI sequence was also in the genomes of P. molurus and Boa constrictor (Boidae), and additionally localized to the centromeric regions of eight chromosome pairs in B. constrictor, suggesting that this sequence originated in the genome of a common ancestor of Pythonidae and Boidae, approximately 86 million years ago. The three stDNA sequences showed no genomic compartmentalization between the macrochromosomes and microchromosomes, suggesting that homogenization of the centromeric and/or pericentromeric stDNA sequences occurred in the macrochromosomes and microchromosomes of these snakes.

Sex chromosome evolution in snakes inferred from divergence patterns of two gametologous genes and chromosome distribution of sex chromosome-linked repetitive sequences

“…The amplification of repetitive sequences has frequently been associated with heterochromatinization of Y and W chromosomes in numerous animal and plant species (e.g., [28, 29, 57–59]). As nearly all colubrid, elapid, and viperid species have heterochromatic W chromosomes [12, 30, 57, 60, 61], our results suggest that heterochromatinization with accumulation of the EQU-BglI-15 and (AGAT)n sequences occurred on the W chromosomes in the common ancestor of Colubridae, Elapidae, and Viperidae (Fig. 6).…”

Characterization of a satellite DNA in the genera Lacerta and Timon (Reptilia, Lacertidae) and its role in the differentiation of the W chromosome

“…Several studies on satDNA have been carried out also in squamate reptiles. In this taxon, satDNAs have been isolated and characterized in skinks (Giovannotti, Nisi Cerioni, & CaputoV, , ), snakes (Matsubara et al., ; Singh, Purdom, & Jones, ), monitor lizards (Chaiprasertsri et al., ; Prakhongcheep et al., ), and lacertids (Capriglione, Olmo, Odierna, Smith, & Miller, , , , , ; Ciobanu, Roudykh, Grechko, & Kramerov, , , ; Grechko, Ciobanu, Darevsky, & Kramerov, , ; Giovannotti et al., ; Rojo et al., ), with this latter taxon being the most studied squamates with reference to satDNAs so far.…”

Karyotype Analysis of Four Blind Snake Species (Reptilia: Squamata: Scolecophidia) and Karyotypic Changes in Serpentes

“…The karyotypes of 3 diploid scolecophidian species, X. vermicularis , L. simonii , and M. macrorhyncha , had 8 pairs of macrochromosomes, just as the standard karyotype of alethinophidian species [Beçak et al, 1962[Beçak et al, , 1964Beçak and Beçak, 1969;Singh, 1972;Ota, 1999;Olmo and Signorino, 2005;Matsubara et al, 2006Matsubara et al, , 2015bMatsubara et al, , 2016a. On the contrary, the numbers of microchromosomes in these scolecophidian species were fewer than those in the standard alethinophidian karyotype.…”

“…For Cbanding analyses, chromosome slides were prepared from fibroblasts cultured without BrdU treatment and stained using the CBG (C-bands by barium hydroxide using Giemsa) method [Sumner, 1972]. Chromosome slides from 6 alethinophidians, E. quadrivir-gata (Colubridae), Rhabdophis tigrinus (Colubridae), Python bivittatus (Pythonidae), Boa constrictor (Boidae), Protobothrops flavoviridis (Viperidae), and Bitis arietans (Viperidae) were prepared in our previous studies [Matsuda et al, 2005;Matsubara et al, 2006Matsubara et al, , 2015bMatsubara et al, , 2016a.…”

“…The karyotypes are highly conserved in the Alethinophidia, and the common chromosome number is 2n = 36, comprising 8 pairs of macrochromosomes and 10 pairs of microchromosomes [Beçak et al, 1962[Beçak et al, , 1964Beçak and Beçak, 1969;Singh, 1972;Ota, 1999;Matsubara et al, 2006Matsubara et al, , 2015bMatsubara et al, , 2016a. This karyotype is not limited to a few particular lineages but prevails in almost all alethinophidian families [Olmo and Signorino, 2005] except for 2 small colubroid families, Xenodermatidae and Achrocordidae [Ota et al, 1991a;Rovatsos et al, 2015aRovatsos et al, , 2018; thus, the common ancestor of Alethinophidia probably had this karyotype.…”