A spontaneous translocation heterozygote involving centromere regions in Gomphocerus sibiricus (L.) (Orthoptera: Acrididae)

A spontaneous interchange with breaks in the centromeric regions of the L₂ and L₃ submetacentric chromosome pairs is described, using the C-banding technique, in a male of the mountain grasshopper Gomphocerus sibiricus (2n=17). In 100% of the examined cells from standard follicles of the mutant, the interchange was present as a ring of four and concordant separations during anaphase-I were always observed. The orientation of these rings is predominantly either adjacent I or II and a very much lower frequency was detected for the alternate type. Fertility is therefore expected to be low. — A single follicle was found where the centromeric region of the 3² chromosome had split, resulting in two telocentric chromosomes. At meiosis chains with five centromeric regions resulted. The nature of the original interchange has been interpreted on the basis of this new aberration. — A large variation in the number of nucleoli is regularly present in spermatocytes at the same stage and differences between the two karyotypes (mutant and standard) could not be demonstrated using Ag-staining. This technique has also been used to study the morphology, with respect to number and localization of the adjunct centrioles, of the spermatids in the mutant.