C-heterochromatin and its base composition in holokinetic chromosomes of two species of Heteroptera (Insecta: Hemiptera)

Abstract

Constitutive heterochromatin shows a very diverse distribution pattern and base composition in different species. Serinetha augur (Rhopalidae) and Riptortus pedestris (Alydidae) share the same diploid chromosome complement i.e. 2n = 13 = 10A + 2 m + XO. The banding techniques have been applied for the first time on these two species to compare the distribution pattern and base composition of C-heterochromatin in these species. Serinetha augur and Riptortus pedestris show marked differences in composition and location of C-heterochromatin in autosomes and sex chromosomes. In Serinetha augur, small but distinct sub-terminal C-bands are present whereas in Riptortus pedestris, C-bands are thick and are present at terminal, sub-terminal and interstitial positions. Microchromosomes are C-negative in Serinetha augur but C-positive and CMA₃ bright in Riptortus pedestris. Sex chromosome (X) is heavily C-positive in Serinetha augur but shows localized bands in Riptortus pedestris. In Serinetha augur, some C-bands of autosomes are positive for either DAPI or CMA₃ while some are positive for both. X is DAPI/CMA₃ bright. However, in Riptortus pedestris, all C-bands in the autosomes as well as sex chromosome are DAPI /CMA₃ bright indicating overlapping of AT and GC rich DNA in the heterochromatin.