SPERM SEGREGANTS FROM THE MURINE RB(11.14) HETEROZYGOTE FERTILIZING IN-VIVO AND IN-VITRO

Segregants of the Rb(11,14) translocation in 17 heterozygous male mice were analyzed in G- and C-banded first-cleavage metaphases after in v ivo (n = 440) and in vitro (n = 267) fertilization. Mating intervals o f 3 and 14 d provided unaged and physiologically aged sperm for the oo cytes, which were from chromosomally normal females, Significantly mor e normal than balanced sperm segregants were seen in both the in vivo fertilized (P < 0.01) and in vitro fertilized (P < 0.001) study groups . The distortion was elevated in vitro (P < 0.02), unaccompanied by a sex-ratio distortion, and had a segregant distribution that was indepe ndent of sperm age; thus it differs from that seen for other transloca tions. The findings argue for chromosome-specific effects of Robertson ian translocations on sperm function. A significantly (P < 0.05) incre ased hyperhaploidy rate (unrelated to the translocation) supports the sperm-aging hypothesis.