title: Molecular characterization of Rhodnius prolixus' embryonic cuticle.
abstract: The embryonic cuticle (EC) of Rhodnius prolixus envelopes the entire body of the embryo during hatching and provides physical protection, allowing the embryo to pass through a narrow chorionic border. Most of the knowledge about the EC of insects is derived from studies on ultrastructure and secretion processes during embryonic development, and little is known about the molecular composition of this structure. We performed a comprehensive molecular characterization of the major components extracted from the EC of R. prolixus, and we discuss the role of the different molecules that were identified during the eclosion process. The results showed that, similar to the post-embryonic cuticles of insects, the EC of R. prolixus is primarily composed of carbohydrates (57%), lipids (19%), and proteins (8%). Considering only the carbohydrates, chitin is by far the major component (approximately 70%), and it is found primarily along the body of the EC. It is scarce or absent in its prolongations, which are composed of glycosaminoglycans. In addition to chitin, we also identified amino (15%), neutral (12%) and acidic (3%) carbohydrates in the EC of R. prolixus. In addition carbohydrates, we also identified neutral lipids (64.12%) and phospholipids (35.88%). Proteomic analysis detected 68 proteins (55 were identified and 13 are hypothetical proteins) using the sequences in the R. prolixus genome (http://www.vectorbase.org). Among these proteins, 8 out of 15 are associated with cuticle metabolism. These proteins are unequivocally cuticle proteins, and they have been described in other insects. Approximately 35% of the total proteins identified were classified as having a structural function. Chitin-binding protein, amino peptidase, amino acid oxidase, oxidoreductase, catalase and peroxidase are all proteins associated with cuticle metabolism. Proteins known to be cuticle constituents may be related to the function of the EC in assisting the insect during eclosion. To our knowledge, this is the first study to describe the global molecular composition of an EC in insects.
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; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, 21941-902 Rio de Janeiro, Brazil.
authors.forename: Mônica F
authors.initials: MF
authors.lastname: Moreira
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, 21941-902 Rio de Janeiro, Brazil.
authors.forename: Geórgia C
authors.initials: GC
authors.lastname: Atella
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: Ana Lúcia
authors.initials: AL
authors.lastname: Oliveira-Carvalho
authors.affiliation: Universidade Federal do Rio de Janeiro, Escola de Educação Física e Desportos, 21941-599 Rio de Janeiro, RJ, Brazil.
authors.forename: Roberto
authors.initials: R
authors.lastname: Eizemberg
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: David
authors.initials: D
authors.lastname: Majerowicz
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, 21941-902 Rio de Janeiro, Brazil.
authors.forename: Ana C A
authors.initials: AC
authors.lastname: Melo
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: Russolina B
authors.initials: RB
authors.lastname: Zingali
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, 21941-902 Rio de Janeiro, Brazil. Electronic address: masuda@bioqmed.ufrj.br.
authors.forename: Hatisaburo
authors.initials: H
authors.lastname: Masuda
mesh_terms: D000818:Animals; D001483:Base Sequence; D050260:Carbohydrate Metabolism; D002686:Chitin / Q000378:metabolism; D019476:Insect Proteins / Q000737:chemistry*; D050356:Lipid Metabolism; D040901:Proteomics; D012239:Rhodnius / Q000737:chemistry* / Q000196:embryology*
chemical_list: D019476:Insect Proteins; D002686:Chitin
keywords: Carbohydrates; Eclosion; Embryonic cuticle; Lipids; Proteins; Rhodnius prolixus