Chitin deposition on the embryonic cuticle of Rhodnius prolixus: The reduction of CHS transcripts by CHS–dsRNA injection in females affects chitin deposition and eclosion of the first instar nymph

Chitin deposition on the embryonic cuticle of Rhodnius prolixus: The reduction of CHS transcripts by CHS–dsRNA injection in females affects chitin deposition and eclosion of the first instar nymph

In a previous study, we found that the embryonic cuticle of Rhodnius prolixus is a chitin-based structure that helps the first instar nymph to hatch from the chorion. Here, we investigated how the reduction of transcripts induced by CHS dsRNA injection affects R. prolixus embryogenesis and eclosion....

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Bibliographic Details
Published in:Insect biochemistry and molecular biology Vol. 51; pp. 101 - 109
Main Authors: Souza-Ferreira, Paula S., Mansur, Juliana F., Berni, Matheus, Moreira, Monica F., dos Santos, Roberto Eizemberg, Araújo, Helena M. Marcolla, de Souza, Wanderley, Ramos, Isabela B., Masuda, Hatisaburo
Format: Journal Article
Language:English
Published: England Elsevier Ltd 01-08-2014
Subjects:
Animals
Chitin - metabolism
Chitin synthase
Chitin Synthase - genetics
dsRNA
Eclosion
Embryogenesis
Embryonic cuticle
Female
Nymph - genetics
Nymph - metabolism
Oviposition - genetics
Oviposition - physiology
Rhodnius - embryology
Rhodnius - genetics
Rhodnius - metabolism
Rhodnius prolixus
RNA Interference
RNA, Messenger
dsRNA
Eclosion
Embryogenesis
Rhodnius prolixus
Chitin synthase
Embryonic cuticle
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Summary:In a previous study, we found that the embryonic cuticle of Rhodnius prolixus is a chitin-based structure that helps the first instar nymph to hatch from the chorion. Here, we investigated how the reduction of transcripts induced by CHS dsRNA injection affects R. prolixus embryogenesis and eclosion. Deposition of chitin in the embryonic cuticle begins later at embryogenesis, around day 8, and ends approximately at day 15, when the insects are ready for eclosion. In R. prolixus, chitin deposition follows pari passu with the synthesis of the chitin synthase mRNA, indicating a regulation at the transcriptional level. The reduction of the chitin synthase gene transcripts by the injection of CHS dRNA prevented chitin deposition during embryonic cuticle formation, being lethal to hatching nymphs, which end up dying while stuck in the chorionic border trying to leave the chorion. The successful eclosion rates were reduced by 60% in animals treated with CHS dsRNA when compared to animals injected with a control (dsRNA no related gene or water). We found that the harmful effects on oviposition and eclosion are possibly due to changes in the structure of the embryonic cuticle, as observed by directly comparing the morphology of control and chitin-deficient embryonic cuticles under the transmission electron microscope. The lack of chitin and changes in its morphological characteristics appears to alter the embryonic cuticle physiology and functionality. Additionally, we observed that the effects of CHS dRNA treatment on R. prolixus females lasted up to 3 egg-laying cycles (∼100 days), pointing to R. prolixus as a useful model for developmental studies. [Display omitted] •We investigated how the lack of chitin affects embryonic cuticle formation.•CHS dsRNA injection prevented chitin deposition on the embryonic cuticle.•The absence of chitin on the embryonic cuticle is harmful for hatching nymphs.•Our findings indicate that the embryonic cuticle assists insect emergence.•The RNAi effects of CHS dsRNA lasted up to three egg-laying cycles.
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ISSN:0965-1748
1879-0240
DOI:10.1016/j.ibmb.2013.12.004