昆虫为适配生存与繁殖需求进化出了多样合成分泌丝蛋白的能力。其中家蚕幼虫在末龄产生的丝胶是蚕丝工业排放的主要污废，又是多学科关注的昆虫丝生物材料，但目前尚缺乏对其蛋白质组分及相应生物学功能的逐一明确。项目前期发现丝胶蛋白Ser1、Ser3是家蚕末龄丝胶的主要成分，并通过基因编辑敲除了其编码基因，表型调查显示Ser1敲除不影响家蚕泌丝和营茧，而Ser3敲除则导致蚕茧变薄、茧丝产量显著降低，因此我们提出了Ser1与Ser3在参与家蚕泌丝和营茧中发挥差异化功能的科学假说。本研究将以Ser1、Ser3的单基因敲除和双基因敲除突变体作为实验模型，比较不同丝胶蛋白缺失条件下的丝蛋白合成分泌模式、蚕茧经济性状和纤维力学性能，探索丝胶蛋白影响丝纤维形成的关键环节及作用机理，基本阐明Ser1、Ser3的生物学功能，为进一步开发家蚕低/无丝胶茧丝品系、拓宽昆虫丝胶蛋白的应用范围和解析昆虫的泌丝机制提供理论依据。

Insects have evolved the ability to synthesize and secrete a variety of silk proteins for survival and reproduction. Sericin produced by silkworm at the last larval stage is the main waste discharged by the silk industry, and it is also the biological material of insect silk protein concerned by many disciplines. In the early stage of the project, we found that the Ser1 and Ser3 were the main components of sericin. Then Ser1 and Ser3 were knocked out by CRISPR/Cas9 system, and the mutant phenotype investigation showed that the knockout of Ser1 did not affect the silk secretion and cocooning, while the knockout of Ser3 caused a thinning cocoon and significantly reduced cocoon production. Accordingly, we proposed a scientific hypothesis that Ser1 and Ser3 played different functions in silk secretion and cocooning. This study will regard single sericin gene knock out mutant and double sericin gene knockout mutant as the experimental model, and then compare the differences of silk protein secreted mode, cocoon economic characters, and mechanics performance among the different sericin loss-of-function mutants, to explore the effect of the sericin protein of silk fiber key link and mechanism and clarify the function mechanism of Ser1 and Ser3 in the process of silk secretion and cocooning. The results will provide a theoretical basis for developing sericin-low/free silkworm strain, enlarging the application range of insect sericin protein, and parsing the secrete mechanism of insect silk.