Characterization of Parasarcophaga heterochromatin. II. Polytene chromosomes

The polytene chromosomes of six species of Parasarcophaga were examined by C-, quinacrine (Q)-, Hoechst 33258 (H)-, Hoechst/actinomycin D (H/AMD)- and acridine orange (AO)- staining methods to characterize their heterochromatin. In the polytene karyotype the sex chromosomes do not polytenize and are represented by a granular mass of heterochromatin which is C super(+), Q super(+), H super(+) and fluoresces yellowish green with acridine orange. The autosomal elements reveal an identical distribution of heterochromatin with all the banding techniques and the fluorescence characteristics indicate AT-rich fast-reassociating DNA in these regions. Thus, in the polytene system of Parasarcophaga) besides the underreplicative heterochromatin there is a considerable amount of heterochromatin which seems to be correplicative during polytenization.