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LmCht5-1 promotes pro-nymphal molting during locust embryonic development

Author:
Zhang, Tingting, Liu, Weiwei, Li, Daqi, Gao, Lu, Ma, Enbo, Zhu, Kun Yan, Moussian, Bernard, Li, Sheng, Zhang, Jianzhen
Source:
Insect biochemistry and molecular biology 2018 v.101 pp. 124-130
ISSN:
0965-1748
Subject:
Locusta migratoria, apolysis, chitin, chitinase, embryogenesis, hatching, histology, insects, nymphs
Abstract:
Chitinases, key enzymes involved in degradation of chitin, have been repeatedly shown to play an indispensable role during insect post-embryonic molting processes at stage transitions. However, how chitinases affect insect embryonic development remains to be analyzed. In this study, we investigated the role of chitinase 5–1 (LmCht5-1) during embryonic development of the hemimetabolous insect Locusta migratoria. LmCht5-1 transcript levels were high in pro-nymphs during late embryogenesis. The respective protein localized to both the pro-nymphal and, to a much lesser extent, the newly formed nymphal cuticle. After injection of double stranded RNA against LmCht5-1 into 8 days old embryos, LmCht5-1 transcripts were strongly reduced. Most of dsLmCht5-1-injected pro-nymphs failed to develop to first-instar nymphs and died at or before hatching. Histological analyzes showed that degradation of the pro-nymph cuticle was blocked in these animals. At the ultra-structural level, we found that LmCht5-1 was needed for the degradation of the lamellar procuticle, while the separation of the procuticle from the epicuticle and epidermis (apolysis) was independent of LmCht5-1 function. Taken together, our results indicate that LmCht5-1 and other yet unknown degrading enzymes act in parallel at distinct positions of the cuticle during molting of the pro-nymph to the first-instar nymph during locust embryogenesis.
Agid:
6157576