Sperm chromosome study of two bulls heterozygous for different Robertsonian translocations.
Haploid chromosomes of a total of 354 spermatozoa from two bulls heterozygous for different Robertsonian translocations, a Holstein-Friesian bull carrying a t(1;21) and a Japanese Black bull carrying a t(7;21), were analyzed using an interspecific in vitro fertilization system with zona-free hamster oocytes. The proportion of chromosomally normal and balanced spermatozoa was approximately equal in both carriers (51.8% and 47.0% in the 1/21 carrier, and 47.3% and 50.0% in the 7/21 carrier). The combined incidences of normal and balanced spermatozoa, i.e., incidences of spermatozoa resulting from alternate meiotic segregation were very high (98.8% and 97.3%) in both carrier. On the contrary, the incidences of chromosomally unbalanced spermatozoa resulting from adjacent meiotic segregation were only 0.6% and 2.7%. These results indicate that the alternate segregation of a trivalent chromosome is predominant in these Robertsonian translocation carriers.
Tateno
H
H
Department of Biological Sciences, Asahikawa Medical College, Japan.
Miyake
Y I
YI
Mori
H
H
Kamiguchi
Y
Y
Mikamo
K
K
D000818:Animals; D002417:Cattle / Q000235:genetics*; D002875:Chromosomes / Q000648:ultrastructure; D006224:Cricetinae; D005260:Female; D005307:Fertilization in Vitro; D006579:Heterozygote; D007621:Karyotyping; D008297:Male; D013094:Spermatozoa / Q000648:ultrastructure; D014178:Translocation, Genetic