title: 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.
abstract: 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.
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Bioquímica Médica, Programa de Biologia Molecular e Biotecnologia, 21941-902 Rio de Janeiro, RJ, Brazil.
authors.forename: Paula S
authors.initials: PS
authors.lastname: Souza-Ferreira
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Química, 21941-909 Rio de Janeiro, RJ, Brazil.
authors.forename: Juliana F
authors.initials: JF
authors.lastname: Mansur
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Ciências Biomédicas, 21941-970 Rio de Janeiro, RJ, Brazil.
authors.forename: Matheus
authors.initials: M
authors.lastname: Berni
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Química, 21941-909 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Brazil.
authors.forename: Monica F
authors.initials: MF
authors.lastname: Moreira
authors.affiliation: Universidade Federal do Rio de Janeiro, Escola de Educação Física e Desportos, 21941599 Rio de Janeiro, RJ, Brazil.
authors.forename: Roberto Eizemberg
authors.initials: RE
authors.lastname: dos Santos
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Ciências Biomédicas, 21941-970 Rio de Janeiro, RJ, Brazil.
authors.forename: Helena M Marcolla
authors.initials: HM
authors.lastname: Araújo
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Biofísica Carlos Chagas Filho, 21941-902 Rio de Janeiro, RJ, Brazil.
authors.forename: Wanderley
authors.initials: W
authors.lastname: de Souza
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Bioquímica Médica, Programa de Biologia Molecular e Biotecnologia, 21941-902 Rio de Janeiro, RJ, Brazil.
authors.forename: Isabela B
authors.initials: IB
authors.lastname: Ramos
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Bioquímica Médica, Programa de Biologia Molecular e Biotecnologia, 21941-902 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Brazil. Electronic address: masuda@bioqmed.ufrj.br.
authors.forename: Hatisaburo
authors.initials: H
authors.lastname: Masuda
mesh_terms: D000818:Animals; D002686:Chitin / Q000378:metabolism; D002687:Chitin Synthase / Q000235:genetics; D005260:Female; D009758:Nymph / Q000235:genetics* / Q000378:metabolism*; D010058:Oviposition / Q000235:genetics* / Q000502:physiology; D034622:RNA Interference; D012333:RNA, Messenger; D012239:Rhodnius / Q000196:embryology* / Q000235:genetics* / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D002686:Chitin; D002687:Chitin Synthase
keywords: Chitin synthase; Eclosion; Embryogenesis; Embryonic cuticle; Rhodnius prolixus; dsRNA