Translocation between Sperm and Egg Chromosomes as Evidence that Breakage Precedes Union

Abstract

In Drosophila melano-gaster expts. with 2 dosages of x-rays showed that total frequency of translocations varies approx. as the 1.5 power of dosages used. + Non-ring Oregon K [male][male] and Xc2 ring [male][male] from Beadle''s stock were x-rayed and mated to virgin [female][female] (yy bw e ey) with attached X''s and a Y chromosome. Progeny of 1 culture among 11,569 fertile backcrosses in which Xc2 [male][male] had been used showed an unexpected type of segregation. [male][male] were ebony and majority of [female][female] non-ebony. A translocation between sperm and egg chromosomes, the paternal 3rd with normal allele for ebony and maternal Y, seems most likely explanation. This indicates that breakage precedes union and that union of broken pieces in spermatozoa can be delayed until after fertilization.