Discovery of new chromosomal markers through repeatome analysis of Caryophyllaeus laticeps (Caryophyllidea).

Abstract

Genomic repetitive elements are essential structural and functional components of most eukaryotes and have attracted the attention of researchers in recent years. Despite the well-documented features of the karyotype of the tapeworm species Caryophyllaeus laticeps, knowledge about the content and distribution of repetitive elements on its chromosomes is limited. To gain a more comprehensive understanding of the composition of the repetitive DNA, we used a combination of bioinformatic, cytogenetic and molecular techniques to characterise the repetitive DNA content of this species. RepeatExplorer2 analysis revealed that transposable elements are predominantly present in the C. laticeps genome. The most suitable repeat families were selected for fluorescence mapping on the chromosomes, and most of them showed a scattered hybridisation pattern. In this study, we identified three new chromosomal markers: small nuclear U1 DNA (snDNA), the 5S ribosomal DNA (5S rDNA) and a satellite DNA named ClatSat14-167, each of which hybridises to a single locus at different chromosomal locations, allowing accurate identification of three pairs of chromosomes. These markers could be very valuable tools for future evolutionary studies and greatly enrich the limited cytogenetic data for tapeworms. In addition, an increased frequency of chromosomal aberrations was detected, reaffirming previous findings on the possible adverse effects of environmental pollution on the chromosomes of the species studied.