Abstract
To identify genes that are differentially expressed in the developing
testis we used representational difference analysis of complementary
DNA from gonads of mouse embryos at 13.5 days postcoitum (dpc). Three
genes were identified. One of them was a novel gene termed
tescalcin that encoded a putative EF-hand
Ca2+-binding protein. The open reading frame consisted of
642 nucleotides encoding a protein with 214 amino acids. Analysis of
the predicted amino acid sequence revealed an
N-myristoylation motif and several phosphorylation sites
in addition to an EF-hand Ca2+-binding domain.
Tescalcin messenger RNA (mRNA) was present in fetal
testis, but not in ovary or mesonephros, and was restricted to the
testicular cords. Its expression was first detected in the male gonad
at 11.5 dpc and demonstrated a pattern consistent with a role in the
testis at the early stages of testis differentiation. Tescalcin is
expressed in the testis of KitW/W-v mice, indicating that
it is not dependent on the presence of germ cells. The other two genes
identified were collagen IX α3 (Col9a3) and
Renin. Col9a3 expression was present at
low levels in male and female gonads at 11.5 dpc. Thereafter, it was
markedly up-regulated in the male, but remained very low in the female.
Expression of Col9a3 was restricted to testicular cords
and was also detected in testis of KitW/W-v mice.
Renin mRNA was first detected in testis at 12.5 dpc,
increased thereafter, and reached a peak at 16.5 dpc.
Renin mRNA was localized in cells of the interstitium
and cells at the border between the gonad and mesonephros. Expression
of Renin in the ovary was not detected using standard
conditions.