The heterochromatic region of chromosomes contains highly repeated satellite DNAs with no or very few genes and is usually transcriptionally inactive. Its repetitive character has led to the suggestion that it is »junk DNA« with no utility, although some important inheritance functions have been mapped to it. Beetles from the family Tenebrionidae (Insecta, Coleoptera) contain a substantial amount of heterochromatin and satellite DNA in their genome and represent a suitable system for structural and organizational studies. Here, the data on the primary and higher order structure and organization of satellite DNAs from ten different tenebrionid species are presented, as well as on mutational processes effecting their evolution. Using these data, we have tried to determine conserved structural elements within satellites which can be important for maintaining the heterochromatin structure and compactness. Such analyses could help to define the structural components of the chromosome responsible for some heterochromatic functions, like chromosome pairing, centromere function and sister chromatid adhesion
