Washburn L L, Lee B K, Eicher E M
Jackson Laboratory, Bar Harbor, Maine 04609.
Genet Res. 1990 Oct-Dec;56(2-3):185-91. doi: 10.1017/s001667230003528x.
We previously identified a primary sex-determining locus, Tas, on mouse Chr 17 that causes ovarian tissue development in C57BL/6J Thp/+ and TOrl/+ individuals if the AKR/JY chromosome is present. We hypothesized that Tas is located within the region of Chr 17 deleted by Thp and TOrl and that C57BL/6J carries a diagnostic Tas allele, based on the observation that ovarian tissue develops in XY mice when Thp is on a C57BL/6J inbred strain background, whereas normal testicular development occurs when Thp is on a C3H/HeSnJ inbred strain background. To test this hypothesis, we mated (C57BL/6J x C3H/HeSnJ)F1 females to C57BL/6J Thp/+ hermaphrodites. As expected, half of the XY Thp/+ offspring developed ovarian and testicular tissue while half developed exclusively testicular tissue. Unexpectedly, the inheritance of selected Chr 17 molecular loci was independent of gonadal development, as half of the male and hermaphroditic offspring inherited C3H/HeSnJ-derived Chr 17 loci and half inherited C57BL/6J-derived Chr 17 loci. We conclude that for ovarian tissue to develop in an XY Thp/+ or XY TOrl/+ individual (1) Tas must be present in a hemizygous state, which is accomplished by heterozygosity for the Thp or TOrl deletions; (2) the AKR/J-derived Y chromosome must be present; and (3) an additional locus involved in primary sex determination must be present in a homozygous C57BL/6J state. This newly identified gene may be one of the previously defined loci, tda-1 or tda-2.
我们之前在小鼠17号染色体上鉴定出一个主要的性别决定位点Tas，如果存在AKR/JY染色体，它会导致C57BL/6J Thp/+和TOrl/+个体发育出卵巢组织。基于以下观察结果，我们推测Tas位于Thp和TOrl缺失的17号染色体区域内，且C57BL/6J携带一个诊断性的Tas等位基因：当Thp位于C57BL/6J近交系背景时，XY小鼠会发育出卵巢组织；而当Thp位于C3H/HeSnJ近交系背景时，则会出现正常的睾丸发育。为了验证这一假设，我们将（C57BL/6J×C3H/HeSnJ）F1雌性小鼠与C57BL/6J Thp/+雌雄同体小鼠交配。正如预期的那样，一半的XY Thp/+后代同时发育出卵巢和睾丸组织，而另一半则只发育出睾丸组织。出乎意料的是，所选17号染色体分子位点的遗传与性腺发育无关，因为一半的雄性和雌雄同体后代继承了C3H/HeSnJ来源的17号染色体位点，另一半继承了C57BL/6J来源的17号染色体位点。我们得出结论，对于XY Thp/+或XY TOrl/+个体要发育出卵巢组织，必须满足以下条件：（1）Tas必须以半合子状态存在，这可通过Thp或TOrl缺失的杂合性来实现；（2）必须存在AKR/J来源的Y染色体；（3）另一个参与主要性别决定的位点必须以纯合C57BL/6J状态存在。这个新鉴定出的基因可能是之前定义的位点tda - 1或tda - 2之一。
