Exploring Satellite DNAs: Specificities of Bivalve Mollusks Genomes

Noncoding DNA sequences repeated in tandem or satellite DNAs make an integral part of every eukaryotic genome. Development and application of new methodological approaches through time enabled gradual improvement in understanding of structural and functional roles of these sequences, early misconsidered as "junk DNA". Advancing approaches started adding novel insights into details of their existence on the genomic scale, traditionally hard to access due to difficulties in analyzing long arrays of nearly identical tandem repeats of a satellite DNA. In turn, broadened views opened space for the development of new concepts on satellite DNA biology, highlighting also specificities coming from different groups of organisms. Observed diversities in different aspects and in organizational forms of these sequences proclaimed a need for a versatile pool of model organisms. Peculiarities of satellite DNAs populating genomes of bivalve mollusks, an important group of marine and fresh-water organisms, add to the diversity of organizational principles and associated roles in which tandemly repeated sequences contribute to the genomes.