A GENETIC-ANALYSIS OF THE SEX-DETERMINING GENE, TRA-1, IN THE NEMATODE CAENORHABDITIS-ELEGANS
A GENETIC-ANALYSIS OF THE SEX-DETERMINING GENE, TRA-1, IN THE NEMATODE CAENORHABDITIS-ELEGANS
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DOI：
10.1101/gad.1.7.731
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发表时间：
1987-09-01
影响因子：
10.5
通讯作者：
HODGKIN, J
中科院分区：
文献类型：
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作者：
HODGKIN, J
秀丽隐杆线虫的正常性别为自交两性(XX)和雄性(XO)。常染色体基因tra-1是控制性别表型的主要开关基因。对43个功能丧失(Lf)tra-1等位基因和22个功能获得(Gf)tra-1等位基因的突变表型进行了描述和讨论。Tra-1(Lf)等位基因是隐性的，通常是男性化的。最严重的突变(例如8个已确认的琥珀等位基因中的7个)可以将XX动物转变为可生育的雄性动物。这些突变对XO动物(已经是雄性动物)几乎没有影响，但会导致XO性腺发育的一些异常，表明tra-1在两性正常发育中具有功能，尽管其主要功能仅限于XX两性。较弱的tra-1(Lf)等位基因导致XX动物的不完全雄性化，导致不同的间性表型。Tra-1(Gf)等位基因是显性的，具有相反的女性化效应。22只动物中有6只可以将XO动物转变为可生育的雌性动物或两性动物，而其余的动物则会导致部分女性化。所有22只动物都将XX动物转变为有生育能力的雌性动物。有限的基因内定位表明该基因很大，并且gf等位基因映射到与lf等位基因不同的位置。结果表明，tra-1基因在野生型性发育中具有多种作用。首先，在XX动物的所有非腺组织中，tra-1的活性决定了雌性而不是雄性的发育。其次，在XX动物的体细胞性腺中，tra-1的活性决定了雌性的发育。第三，在XX胚系中，高水平的tra-1活性可能抑制精子发生，从而帮助两性人从精子发生向卵子发生的转换。这三个功能都是女性化的，并且是XX动物特有的；该基因在XO动物中也有一些次要的功能，这些功能是帮助正常的男性体细胞性腺发育和促进男性丰富的精子发生。在缺乏tra-1活性的情况下，精子发生和卵子发生都可能发生低水平。这个基因的功能和调控都必须是复杂的。
The normal sexes of Caenorhabditis elegans are the self-fertilizing hermaphrodite (XX) and the male (XO). The autosomal gene tra-1 is a major switch gene controlling sexual phenotype. Mutant phenotypes of 43 loss-of-function (lf) tra-1 alleles and 22 gain-of-function (gf) tra-1 alleles are described and discussed. The tra-1(lf) alleles are recessive and, in general, masculinizing. The most severe mutations (such as seven out of eight identified amber alleles) can transform XX animals into fertile males. These mutations have little effect on XO animals (which are male already) but lead to some abnormalities in XO gonadal development, indicating that tra-1 has functions in normal development of both sexes, although its major function is confined to the XX hermaphrodite. Weaker tra-1(lf) alleles lead to incomplete masculinization of XX animals, resulting in a variety of intersexual phenotypes. the tra-1(gf) alleles are dominant and have an opposite, feminizing effect. Six out of 22 can transform XO animals into fertile females or hermaphrodites, whereas the remainder cause partial feminization. All 22 transform XX animals into fertile females. Limited intragenic mapping indicates that the gene is large and that gf alleles map to a location different from lf alleles. The results suggest that the tra-1 gene has several roles in wild-type sexual development. First, tra-1 activity dictates female, as opposed to male, development in all nongonadal tissues of XX animals. Second, tra-1 activity dictates female development in the somatic gonad of XX animals. Third, a high level of tra-1 activity may act to inhibit spermatogenesis in the XX germ line, thereby assisting the switch from spermatogenesis to oogenesis in the hermaphrodite. These three functions are all feminizing and specific to the XX animal; the gene also has minor functions in the XO animal, which are to assist normal male somatic gonad development and to promote abundant spermatogenesis in males. A low level of both spermatogenesis and oogenesis can occur in the absence of tra-1 activity. Both the function and the regulation of this gene must be complex.