G- and C-Banding in the Australian grasshopper Phaulacridium vittatum

Abstract

The G- and C-banding patterns of Phaulacridium vittatum (Orthoptera: Acrididae) chromosomes have been investigated. The autosomes and sex chromosomes are similar in showing light staining procentric C-bands and dark staining procentric C-bands. One autosomal pair has a variable distal band. The C-banding pattern is similar in mitotic and meiotic cells. The long teleocentric B-chromosome is somewhat different in its staining behaviour, it is only slightly affected by G-banding but on C-banding it appears relatively more deeply staining than other members of the complement and shows some evidence of longitudinal differentiation into bands and interbands. The results provide no evidence for a scheme of evolutionary origin of the B-chromosome from the X or any other large chromosome. One egg pod was observed to contain two embryos having two different B's—a long telocentric BT chromosome and a metacentric B-isochromosome. C-banding patterns suggest that the latter most probably arose from the former via misdivision of the centromere in one of the very early cleavage divisions of the embryo.