a1 Department of Genetics, University of Patras, Greece
A second chromosome of Drosophila melanogaster (symbol 31.1) isolated from a natural population of North-Western Peloponnesus (at a distance of 8 km from the city of Patras) was found to induce recombination in heterozygous males, both in the second and third chromosomes. The present study also revealed the following points. (1) The phenomenon is temperature-sensitive with higher male recombination at 29 °C than at 25 or 15 °C. (2) The temperature-sensitive period is during the larval stage where premeiotic divisions of germ cells take place. (3) Suppression of male recombination in both the second and third chromosomes occurred when 31.1/CyL4 females were used in the matings, and (4) the suppression of male recombination is caused by a cytoplasmic factor of the CyL4/Pm stock.
(Received January 07 1977)
p1 Present address: Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, England.