McCoubrey W K, Nordstrom K D, Meneely P M
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98104.
Science. 1988 Nov 25;242(4882):1146-51. doi: 10.1126/science.2973125.
The signal for sex determination in the nematode Caenorhabditis elegans is the ratio of the number of X chromosomes to the number of sets of autosomes (X/A ratio). By previous genetic tests, elements that feminized chromosomal males appeared to be widespread on the X chromosome, but the nature of these elements was not determined. In experiments to define a feminizing element molecularly, cloned sequences were added to chromosomally male embryos by microinjection into the mother. Three different X-chromosome clones, including part of an actin gene, part of a myosin heavy chain gene, and all of two myosin light chain genes, feminize chromosomal males. Both somatic and germline aspects of sex determination are affected. In contrast, about 40 kilobases of nematode autosomal DNA, phage lambda DNA, and plasmid pBR322 DNA do not affect sex determination. A feminizing region was localized to a maximum of 131 base pairs within an intron of the X-linked actin gene; a part of the gene that does not have this region is not feminizing. The results suggest that short, discrete elements found associated with many X-linked genes may act as signals for sex determination in C. elegans.
线虫秀丽隐杆线虫中性别决定的信号是X染色体数量与常染色体组数的比例（X/A比例）。通过先前的遗传学测试，使染色体雄性雌性化的元件似乎广泛存在于X染色体上，但这些元件的性质尚未确定。在分子层面定义雌性化元件的实验中，通过向母体显微注射，将克隆序列添加到染色体雄性胚胎中。三种不同的X染色体克隆，包括肌动蛋白基因的一部分、肌球蛋白重链基因的一部分以及两个肌球蛋白轻链基因的全部，都能使染色体雄性雌性化。性别决定的体细胞和生殖系方面均受影响。相比之下，约40千碱基的线虫常染色体DNA、噬菌体λDNA和质粒pBR322 DNA不影响性别决定。一个雌性化区域定位于X连锁肌动蛋白基因内含子内最多131个碱基对处；该基因没有这个区域的部分则没有雌性化作用。结果表明，与许多X连锁基因相关的短而离散的元件可能作为秀丽隐杆线虫性别决定的信号。
