Chromosomal localization and variation analysis of 5S rDNA in autotriploid Carassius auratus

Polyploidization can induce a flurry of genetic events and plays an important role in speciation. In this study, we comparatively analyzed the molecular organization, chromosomal locus in natural autotriploid (3nCC, 3 n = 150) and artificial autotriploid gynogenetic (3nG, 3 n = 150) Carassius auratus , diploid Carassius auratus (2nCC, 2 n = 100) and Carassius auratus red var. (RCC, 2 n = 100). Three distinct 5S rDNA sequence types were identified across 3nCC, 3nG 2nCC and RCC. Among these, the sequences in 3nG and 3nCC matched perfectly with those in RCC and 2nCC, respectively. The NTS regions of 5S rDNA in 3nG and 3nCC showed significant base variations compared to RCC and 2nCC, separately. FISH with 5S rDNA probe indicated that the expected number of maternal chromosomal loci was found in both 3nCC and 3nG. These observations indicated that they provide theoretical support for the study of the evolutionary modes and characteristics of rDNA in vertebrates.