Vitamin C (VC) is an essential nutrient for many animals. However, whether insects, including Bombyx mori, can synthesize VC remains unclear. In this article, the optimized HPLC method was used to determine the content of l‐ascorbic acid (AsA) in silkworm eggs, larvae and pupae, and the activity of l‐gulono‐1,4‐lactone oxidase (GULO), a key enzyme in VC synthesis. The RNA interference method was used to determine the effect of the BmGulo‐like gene on embryonic development and GULO activity in the pupal fat body. The AsA content increased significantly during E144 h–E168 h in the late embryonic stage and P48 h–P144 h in the middle‐late pupal stage, in which exogenous VC was not ingested. Furthermore, the body AsA content in larvae fed VC‐free feed also increased with larval stage. The GULO enzymatic activity was present in eggs and the fat bodies of larvae and pupae, even when the larvae were reared with fresh mulberry leaves. Moreover, the activity was higher in the later embryonic stages (E144 h–E168 h) and the early pupal stage (before P24 h). The GULO activity in the pupal fat body dramatically decreased when the screened BmGulo‐like gene (BGIBMGA005735) was knocked down with small interfering RNA; in addition, the survival rate and hatching rate of eggs significantly decreased 21% and 44%, respectively, and embryonic development was delayed. Thus, Bombyx mori can synthesize AsA through the l‐gulose pathway, albeit with low activity, and this synthesis ability varies with developmental stages.

中文翻译：

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家蚕可以根据发育阶段不同程度地通过l-葡萄糖途径合成抗坏血酸

维生素C（VC）是许多动物必不可少的营养素。但是，包括家蚕在内的昆虫是否可以合成VC尚不清楚。在本文中，使用了优化的HPLC法测定的含量升抗坏血酸（ASA）在蚕卵，幼虫和蛹，和活性升gulono-1,4-内酯氧化酶（GULO），VC合成中的关键酶。RNA干扰法用于确定BmGulo样基因对p脂肪体内胚胎发育和GULO活性的影响。在胚胎后期的E144h–E168h和中晚期p阶段的P48h–P144h，AsA含量显着增加，其中未摄入外源VC。此外，幼虫饲喂无VC饲料的体内AsA含量也随着幼虫期的增加而增加。即使在幼虫用新鲜桑叶饲养的情况下，其卵，幼虫和eggs的脂肪体中也存在GULO酶活性。此外，在胚胎后期（E144h–E168h）和p早期（P24h之前）的活性更高。当用小的干扰RNA敲除筛选的BmGulo样基因（BGIBMGA005735）时，p脂肪体内的GULO活性急剧下降。此外，卵的存活率和孵化率分别显着降低了21％和44％，并且胚胎发育被延迟。因此，家蚕可以通过l-葡萄糖途径合成AsA ，尽管活性较低，而且这种合成能力随发育阶段而变化。