A Tandemly Arranged Pattern of Two 5S rDNA Arrays in <b><i>Amolops mantzorum </i></b>(Anura, Ranidae)

Abstract

In an attempt to extend the knowledge of the 5S rDNA organization in anurans, the 5S rDNA sequences of Amolops mantzorum were isolated, characterized, and mapped by FISH. Two forms of 5S rDNA, type I (209 bp) and type II (about 870 bp), were found in specimens investigated from various populations. Both of them contained a 118-bp coding sequence, readily differentiated by their non-transcribed spacer (NTS) sizes and compositions. Four probes (the 5S rDNA coding sequences, the type I NTS, the type II NTS, and the entire type II 5S rDNA sequences) were respectively labeled with TAMRA or digoxigenin to hybridize with mitotic chromosomes for samples of all localities. It turned out that all probes showed the same signals that appeared in every centromeric region and in the telomeric regions of chromosome 5, without differences within or between populations. Obviously, both type I and type II of the 5S rDNA arrays arranged in tandem, which was contrasting with other frogs or fishes recorded to date. More interestingly, all the probes detected centromeric regions in all karyotypes, suggesting the presence of a satellite DNA family derived from 5S rDNA.

Uncovering the molecular organization of unusual highly scattered 5S rDNA: The case of Chariesterus armatus (Heteroptera)

“…In C. armatus, the highly scattered hybridization signals of 5S rDNA, forming multiples blocks over C. armatus chromosomes, suggest putative duplication episodes for this gene that have acquired genome mobility. This contrasts with T. fosteriana that showed discrete blocks (Mizuochi et al, 2007) as commonly seen in other Heteroptera (Bardella et al, 2016) and other animal groups (Insua et al, 2001;Martins and Galetti, 2001;Martins et al, 2002;da Silva et al, 2011;Rodrigues et al, 2012;Merlo et al, 2013;Bueno et al, 2016;Liu et al, 2017). The scattered chromosomal pattern of 5S rDNA seen in C. armatus is unusual, however, it has been reported for other multigene families, such as U2 snDNA in the fish Amphuchthys cryptocentrus and Porichtys plectrodon (Úbeda-Manzanaro et al, 2010).…”

“…NTS size variation has been reported in other species, including for example Pollicipes pollicipes (Perina et al, 2011) and Amolops mantzorum (Liu et al, 2017). Small sized NTS like observed in C. armatus is common in animals (Perina et al, 2011;Rodrigues et al, 2012;Bueno et al, 2016;Liu et al, 2017). Martins and Galetti (2001) suggested NTS of about 80 bp as the minimum size for organization in the genome.…”

“…Remarkably, the size of NTS sequences was highly divergent between the two species, with longer sequences in H. histrio than C. armatus. NTS size variation has been reported in other species, including for example Pollicipes pollicipes (Perina et al, 2011) and Amolops mantzorum (Liu et al, 2017). Small sized NTS like observed in C. armatus is common in animals (Perina et al, 2011;Rodrigues et al, 2012;Bueno et al, 2016;Liu et al, 2017).…”

“…In some species, different variants of 5S rDNAvariable in size and compositionoccupy different chromosomal loci (see Martins and Galetti, 2001;Martins et al, 2002;Rodrigues et al, 2012;Merlo et al, 2013;Bueno et al, 2016;Liu et al, 2017). 5S rDNA variants were noticed for example in grasshoppers (Bueno et al, 2016), crustaceans (Perina et al, 2011), mollusks (Vierna et al, 2009;Vizoso et al, 2011), amphibians (Rodrigues et al, 2012;Liu et al, 2017), freshwater stingrays (Pinhal et al, 2011) and fish (Martins and Galetti, 2001). Interestingly, in H. histrio, which has one cluster per haploid genome, more than two variants of 5S rDNAs were recognized based on the NTS regions; this is similar to the fish D. sargus, which has multiple 5S rDNA variants but exhibits restriction of the clusters to only two chromosomes (Merlo et al, 2013).…”

Chromosomal Evolution in the <b><i>Amolops mantzorum</i></b> Species Group (Ranidae; Anura) Narrated by Repetitive DNAs

“…Two types of repetitive DNAs, a fragment derived from the 5S rDNA type I NTS sequence (5ST1B) [Liu et al, 2017] and 7 different microsatellite motifs, were used as probes for FISH. The 5ST1B fragment, including 42 bp with the sequence 5 ′ -GCCATGC-CAAGGTGAAGAGGGATGGGAGCAGCAAAGGAGATC-3 ′ , was commercially synthesized and end-labeled with TAMRA at the 5 ′ position by Sangon Biotech Ltd. Co. (Shanghai, China).…”