A cDNA probe that exhibits specificity for the rat Y chromosome was ge
nerated by using a set of primers specific to the murine Sry gene, the
sex-determining region of the Y chromosome. A 459-base pair (bp) DNA
fragment was obtained by polymerase chain reaction (PCR) amplification
from male, but not female, rat genomic DNA (EMBL Nucleotide Sequence
Database accession number X89730). This DNA fragment was purified, clo
ned using a vector, and digested with EcoR1 to yield a 270-bp DNA frag
ment. This 270-bp cDNA fragment, when used as a probe in Southern blot
analysis of rat DNA, was observed to bind to three separate bands of
approximately 2.3, 5.0, and 7.0 kb in size. The binding was demonstrat
ed with male, but not female, genomic DNA. Another set of primers was
generated to sequences within the 270-bp fragment that produced a PCR
product of 104 bp. This DNA fragment, when used as a probe in Southern
blot analysis, enabled PCR detection of at least 0.1% male cells in a
mixed population of female cells. These cDNA probes should prove usef
ul in studies designed to track cell populations (e.g., tumor metastas
is and hemopoietic cells after bone marrow transplantation) in syngene
ic male/female pairs. In addition, a cDNA probe that is specific for t
he rat Sry gene might be valuable in studies of fetal male sexual deve
lopment or the study of spermiogenesis.