Transgenic Expression of the piRNA-Resistant Masculinizer Gene Induces Female-Specific Lethality and Partial Female-to-Male Sex Reversal in the Silkworm, Bombyx mori.
Transgenic Expression of the piRNA-Resistant Masculinizer Gene Induces Female-Specific Lethality and Partial Female-to-Male Sex Reversal in the Silkworm, Bombyx mori.
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DOI：
10.1371/journal.pgen.1006203
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发表时间：
2016-08
期刊：
影响因子：
4.5
通讯作者：
Suzuki MG
中科院分区：
文献类型：
--
作者：
Sakai H;Sumitani M;Chikami Y;Yahata K;Uchino K;Kiuchi T;Katsuma S;Aoki F;Sezutsu H;Suzuki MG
在家蚕（B. mori），Fem皮尔纳起源于W染色体并且负责雌性。Fem piRNA-PIWI复合物靶向并切割从Masc基因转录的mRNA。Masc编码一种新的CCCH型锌指蛋白，并且是B的雄性特异性剪接所必需的。家蚕（Bmdsx）转录本。在本研究中，产生了携带编码Fem piRNA抗性Masc mRNA（Masc-R）的转基因的几种家蚕品系。强制表达的Masc-R转基因导致女性特定的致死率在幼虫阶段。其中一个Masc-R菌株在各种组织中弱表达Masc-R。转基因的杂合子女性表达胰岛素样生长因子II mRNA结合蛋白（ImpM）和Bmdsx的Bmdsx同源物的男性特异性同种型。所有检查的女性显示出较低的卵黄蛋白原合成的诱导，并表现出卵巢异常。在异常卵巢中观察到睾丸样组织，值得注意的是，该组织含有相当数量的精子束。转基因的纯合表达导致成年雌性中雄性特异性腹节的形成，并导致雌性生殖器中的部分雄性分化。这些结果表明Masc基因是B雄性化的重要调控基因。桑。在家蚕中，一个W染色体连锁的基因Feminizer（Fem）决定雌性。Fem转录物产生皮尔纳（Fem皮尔纳）和Fem-piRNA-PIWI复合物靶标，并切割从雄性化因子（Masc）转录的mRNA。Bmdsx是性别分化的重要调控基因，Masc是Bmdsx雄性特异性表达所必需的，因此，Masc被认为是雄性所必需的。然而，没有直接的证据表明Masc确实导致了两性异形结构的雄性化。为了阐明这一点，我们建立了携带表达Fem-piRNA抗性Masc基因（Masc-R）的转基因的家蚕品系。Masc-R的转基因表达诱导雌性中下游性别决定基因表达的雄性模式。值得注意的是，这些女性的卵巢表现出含有精子束的睾丸样结构。Masc-R的纯合表达导致成年女性中男性特异性腹段的形成，并诱导女性生殖器中的部分男性分化。因此，Masc可以在形态学水平上诱导雄性，并且足以用于精子发生。这是第一次报告，我们的知识，基因，可以雄性化的鳞翅目昆虫的各种性特征。
In Bombyx mori (B. mori), Fem piRNA originates from the W chromosome and is responsible for femaleness. The Fem piRNA-PIWI complex targets and cleaves mRNAs transcribed from the Masc gene. Masc encodes a novel CCCH type zinc-finger protein and is required for male-specific splicing of B. mori doublesex (Bmdsx) transcripts. In the present study, several silkworm strains carrying a transgene, which encodes a Fem piRNA-resistant Masc mRNA (Masc-R), were generated. Forced expression of the Masc-R transgene caused female-specific lethality during the larval stages. One of the Masc-R strains weakly expressed Masc-R in various tissues. Females heterozygous for the transgene expressed male-specific isoform of the Bombyx homolog of insulin-like growth factor II mRNA-binding protein (ImpM) and Bmdsx. All examined females showed a lower inducibility of vitellogenin synthesis and exhibited abnormalities in the ovaries. Testis-like tissues were observed in abnormal ovaries and, notably, the tissues contained considerable numbers of sperm bundles. Homozygous expression of the transgene resulted in formation of the male-specific abdominal segment in adult females and caused partial male differentiation in female genitalia. These results strongly suggest that Masc is an important regulatory gene of maleness in B. mori. In the silkworm, Bombyx mori, a W-chromosome-linked gene Feminizer (Fem) determines femaleness. Fem transcript yields a piRNA (Fem piRNA) and Fem- piRNA-PIWI complex targets and cleaves mRNAs transcribed from the Masculinizer (Masc). Masc is required for male-specific expression of Bmdsx, which is an important regulatory gene for sexual differentiation, and therefore, Masc is considered to be essential for maleness. However, there has been no direct evidence that Masc indeed causes maleness in sexually dimorphic structures. To clarify this point, we established silkworm strains carrying a transgene that expresses Fem-piRNA-resistant Masc gene (Masc-R). Transgenic expression of the Masc-R induced male mode of expressions of downstream sex-determining genes in females. Notably, ovaries in these females exhibited testis-like structures that contained sperm bundles. Homozygous expression of the Masc-R caused formation of the male-specific abdominal segment in adult females and induced partial male differentiation in female genitalia. Thus, Masc can induce maleness at the morphological level and is sufficient for spermatogenesis. This is the first report to our knowledge on a gene that can masculinize a wide variety of sexual characteristics in lepidopteran insects.