Telomeric satellite DNA functions in regulating recombination.

Molecular and cytogenetical analyses of three sibling species of Australian grasshopper, Atractomorpha australis, A. species-1 and A. similis, resolves one of the long standing problems of highly repeated DNA. In this system satellite DNA functions in regulating the level and position of recombination, irrespective of whether the repeated DNA is located in telomeric or centric regions. Even though the three species do not differ in their euchromatic genome sizes, their relative DNA contents are 1.00/1.10/1.41, the difference in genome size being due solely to visible centric or telomeric blocks of heterochromatin. Antibiotic analytical and preparative ultracentrifugation, in situ hybridization and renaturation kinetic analyses reveal that a large cryptic satellite of A. similis constitutes the heterochromatic telomeric blocks of nearly all autosomes and that the DNA of this satellite is highly repeated. Comparison of these grasshopper data with published literature of heterochromatic rearrangements in Drosophila and with heterochromatin distribution and recombination patterns in diploid plant species reveals that in every case heterochromatin is implicated in some form of alteration in the meiotic recombination system.