After two generations of backcrossing six different Y-consomic strains onto a C57BL/6J inbred mouse strain with a
dominant hemimelia (
Dh) mutation, a small percentage of
Dh/+ males containing a Y chromosome from the AKR/J or RF/J strain showed hermaphrodism; they lacked the right testis and had an ovary and a uterus instead. Approximately 15% of
Dh/+ females considered to be phenotypically normal had the
Sry gene from the AKR/J or RF/J strain; they were actually sex-reversed XY females. Backcrossing of Y chromosomes from BALB/cA, C3H/HeJ, C57BL/6J, DH/Sgn, and DDD/Sgn onto the C57BL/6J strain with
Dh did not result in hermaphrodism or sex reversal in adult mice. Subsequent linkage mapping analysis revealed that at least one C57BL/6J-derived homozygous allele at a locus on chromosome 13 was required for hermaphrodism and sex reversal. This condition was genetically distinct from known inherited sex-reversal conditions. It therefore offers a novel opportunity to investigate the genetic basis of sex determination in mammals.
(Edited by Akira IRITANI, M.J.A.)
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