Effects of Osiris9a on Silk Properties in Bombyx mori Determined by Transgenic Overexpression.

Tingcai Cheng,Xia Zhang,Zhangchuan Peng,Lin Zhang,Chun Liu,Yinfeng Fan

doi:10.3390/ijms21051888

Tingcai Cheng, Xia Zhang + Show 4 more

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https://doi.org/10.3390/ijms21051888

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Abstract

Osiris is an insect-specific gene family with multiple biological roles in development, phenotypic polymorphism, and protection. In the silkworm, we have previously identified twenty-five Osiris genes with high evolutionary conservation and remarkable synteny among several insects. Bombxy mori Osiris9a (BmOsi9a) is expressed only in the silk gland, particularly in the middle silk gland (MSG). However, the biological function of BmOsi9a is still unknown. In this study, we overexpressed BmOsi9a in the silk gland by germline transgene expression. BmOsi9a was overexpressed not only in the MSG but also in the posterior silk gland (PSG). Interestingly, BmOsi9a could be secreted into the lumen in the MSG but not in the PSG. In the silk fiber, overexpressed BmOsi9a interacted with Sericin1 in the MSG, as confirmed by a co-immunoprecipitation assay. The overexpression of BmOsi9a altered the secondary structure and crystallinity of the silk fiber, thereby changing the mechanical properties. These results provide insight into the mechanisms underlying silk proteins secretion and silk fiber formation.

Highlights

The Osiris gene family, first described in Drosophila melanogaster, is a large conserved family in insects [1,2]
By comparing the mean curves, we found that the silk fibers from the wild-type line were stronger than those from the transgenic line (Figure 4C)
Bombxy mori Osiris9a (BmOsi9a) is the only gene in the family that is expressed in the silk gland

Summary

Introduction

The Osiris gene family, first described in Drosophila melanogaster, is a large conserved family in insects [1,2]. Twenty-four Osiris genes have been identified in the D. melanogaster genome, including. D. melanogaster and contribute to octanoic acid resistance in D. sechellia [4,5,6]. Known as gore-tex, encodes an endosomal protein that is essential for envelope curvature, nanopore formation, and odor receptivity and is expressed in developing olfactory trichogen cells [9]. Osiris genes are involved in the immune response in the honey bee [10] and in wing development in Bombxy mori [11,12]. The gene family has conserved biological roles in insect development, phenotypic polymorphism, and protection [13]

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Conclusion