Timing of meiotic crossing‐over in Drosophila melanogaster

Abstract

Investigations on the effect of temperature shock on crossing‐over frequency and interference in the X chromosome of Drosophila melanogaster revealed that a decrease in recombination frequency due to response of oocytes in an early meiotic stage which is known to be coincidental with DNA synthesis was accompanied by a decrease in interference. It is therefore suggested that crossing‐over and DNA synthesis are not coincidental events, and that the target of temperature treatment is some precondition of exchange. Later in meiosis a minor effect on crossing‐over frequency was observed which was not accompanied by any alteration in interference. This later effect may thus be coincidental with the event of exchange itself. © 1973 Mendelian Society of Lund