GONOSOME-AUTOSOME TRANSLOCATIONS IN FOWL: MEIOTIC CONFIGURATIONS AND CHIASMA COUNTS FROM SINGLY AND DOUBLY HETEROZYGOUS COCKERELS

Many X-ray or chemical mutagen-induced chromosome translocations in domestic fowl (Gallus domesticus) are thought to involve microchromosomes as centromere donors to acentric macrochromosomal fragments. In order to study the involvement of microchromosomes in such translocations, and to investigate the possibility that such translocations are reciprocal, meiotic chromosomes from cockerels singly or doubly heterozygous for two different Z-autosome translocations were analyzed. Ring multivalents were observed in 74-94% of cells from cockerels bearing the different translocations, and the presence of microchromosomes in certain multivalents was apparent after C-banding. The results indicate that both Z-autosome translocations involve reciprocal exchange and that a microchromosome is indeed involved in one translocation. Chain multivalents at frequencies of 6% to 26% do not interfere with spermatogenesis in domestic fowl.