Molecular Cytogenetic Study of Heterochromatin in Some Coleopteran Insects

Heterochromatin characteristics have been studied in Leptinotarsa decemlineata belonging to the leaf beetles (Chrysomelidae) and compared to the thoroughly analysed heterochromatin of the mealworm beetle Tenebrio molitor, representing darkling beetles (Tenebrionidae). C-banding reveals heterochromatin in pericentromeric regions of all chromosomes of both species; however heterochromatic blocks of L. decemlineata are significantly smaller in size. Digestion of L. decemlineata genomic DNA with 12 restriction enzymes reveals presence of bands characteristic for repetitive DNA, but again in a significantly lower amount than those found in genomic DNA of T. molitor. While T. molitor exhibits complete correspondence of restriction enzyme effects on naked DNA and mitotic chromosomes, L. decemlineata mitotic chromosomes are resistant to the digestion with restriction enzymes. The results show that two species have similar organization of heterochromatin on chromosomes but differ significantly in its amount. In addition, difference in accessibility to in situ restriction enzyme digestion indicates specificity of heterochromatin structure in the two species. Leptinotarsa decemlineata, Chrysomelidae, Tenebrio molitor, repetitive DNA, heterochromatin