The role of the splicing variant of NOS during the early embryonic development of the silkworm, Bombyx mori

在经盐酸处理的家蚕滞育卵中发现了一氧化氮合酶(NOS)的剪接变异体。剪接变异体(NovNOS-V)缺失一个外显子，编码35个氨基酸残基，在盐酸处理后即有表达。用非滞育卵、滞育卵和盐酸处理的滞育卵分别检测了NOS基因表达和NOS活性。这些基因的表达与一氧化氮合酶活性的变化不平行。这些结果表明，家蚕胚胎发育过程中一氧化氮合酶活性的变化主要是在转录后水平进行调节的。此外，用免疫组织化学方法研究了一氧化氮合酶在滞育卵中的分布和定位，发现一氧化氮合酶主要分布在卵黄细胞中。

A splicing variant of nitric oxide synthase(NOS) was found in HCl-treated diapause eggs of the silkworm, Bombyx mori. The splicing variant(NovNOS-V) lacked one exon of NOS gene that was encoded 35 amino acid residue, and NovNOS-V mRNA was expressed just after HCl-treatment. NOS gene expression and NOS activity were also examined with non-diapause, diapause and HCl-treated diapause eggs, respectively. These gene expressions were not parallel with the changes in NOS activity. These results suggest that the changes in NOS activity are regulated mainly at the level of post-transcription during embryonic development in B. mori. Furthermore, the distribution and localization of NOS were investigated by an immunohistochemical technique using antibodies against the universal NOS, and the localization of NOS was observed mainly in yolk cells in HCl-treated diapause eggs.