Comparative cytogenetic analysis in Erythrolamprus snakes (Serpentes: Dipsadidae) from Argentina

Abstract

We described the karyotypes of five snake taxa from Argentina: Erythrolamprus almadensis, E. ceii, E. poecilogyrus caesius, E. p. schotti and E. p. sublineatus, and also intergrading individuals between the last two subspecies by conventional staining, chromosome bandings and fluorescent in situ hybridization (FISH) with 28S ribosomal DNA probes. Erythrolamprus ceii and E. almadensis share a diploid chromosome number of 2n= 28, whereas in E. poecilogyrus intraspecific variations were observed: E. p. caesius has 2n= 28, E. p. schotti and E. p. sublineatus as well as in the intergrading individuals have 2n= 32. In E. almadensis and E. p. caesius, the 2nd and 6th chromosome pairs respectively are heteromorphic by size, morphology and C-banding pattern. These results allow us to suggest that these chromosome pairs might be considered as the ZW sex chromosomes in these species. The present comparative cytogenetic analyzes contributes to the already remarkable karyotypic variability in Erythrolamprus genus and propose a hypothesis about potential mechanisms involved in the chromosome evolution among taxa analyzed. Furthermore, the karyotypic differences observed between E. p. caesius (2n= 28) and E. p. schotti and E. p. sublineatus (2n= 32) might play a causal role in speciation.

Impact of Repetitive DNA Elements on Snake Genome Biology and Evolution

“…Conversely, the rDNA cluster may also remain highly conserved at the subspecies level, as revealed by Southern blotting analysis in neotropical snakes [ 152 ]. Nucleolar organizer regions, in which rDNA is particularly clustered, have been observed with similar organization on the microchromosomes of snake species, including Liophis poecilogyrus shotti [ 153 ], Bothrops jararacussu , Lacerda, 1884 [ 154 ], and the South American rattlesnake ( C. durissus terrificus , Linnaeus, 1758 [ 19 , 155 ]. Likewise, in the viperid C. viridis Rafinesque, 1818 [ 20 ] and the colubrid Masticophis flagellum (Shaw, 1802) [ 156 ], rDNA repeats are commonly present on two pairs of microchromosomes [ 157 ].…”

Evolutionary insights into the genomic organization of major ribosomal DNA in ant chromosomes

“…Species with multiple rDNA clusters do not usually exhibit silver‐staining in all clusters (reviewed by Sumner, 2003; Vicari et al ., 2008). However, it must be assumed that if a species has only a single NOR (or single 45S rDNA gene site), then it will be transcriptionally active, as evidenced for different organisms (Dobigny et al ., 2002; Barros et al ., 2015; Falcione et al ., 2018; Cholak et al ., 2020; Malimpensa et al ., 2020).…”

Karyomorphological delineation, and the NOR loci on the sex chromosome in three species of Chrysopeleinid (Chrysopeleinae: Colubridae) from Thailand

“…A single NOR was observed on microchromosomes in A. fusca and A. prasina on pair 11 and 10, respectively. The number of NOR loci on one microchromosome pair is frequent in Serpentes (Mezzasalma et al 2014;Falcione et al 2018), while the NOR-bearing may be detected either on macrochromosomes, a microchromosome pair or on macro-and microchromosomes (Mezzasalma et al 2016). NOR on macrochromosome was found in C. ornata interestingly, this species revealed that NORs on the sex chromosome.…”