title: Toll signals regulate dorsal-ventral patterning and anterior-posterior placement of the embryo in the hemipteran Rhodnius prolixus.
abstract: BACKGROUND
  Insect embryonic dorso-ventral patterning depends greatly on two pathways: the Toll pathway and the Bone Morphogenetic Protein pathway. While the relative contribution of each pathway has been investigated in holometabolous insects, their role has not been explored in insects with a hemimetabolous type of development. The hemimetabolous insect Rhodnius prolixus, an important vector of Chagas disease in the Americas, develops from an intermediate germ band and displays complex movements during katatrepsis that are not observed in other orders. However, little is known about the molecular events that regulate its embryogenesis. Here we investigate the expression and function of genes potentially involved in the initial patterning events that establish the embryonic dorso-ventral axis in this hemipteran.
  
  
  RESULTS
  We establish a staging system for early embryogenesis that allows us to correlate embryo morphology with gene expression profiles. Using this system, we investigate the role of Toll pathway genes during embryogenesis. Detailed analyses of gene expression throughout development, coupled with functional analyses using parental RNA interference, revealed that maternal Toll is required to establish germ layers along the dorso-ventral axis and for embryo placement along the anterior-posterior axis. Interestingly, knockdown of the Toll pathway effector Rp-dorsal appears to regulate the expression of the Bone Morphogenetic Protein antagonist Rp-short-gastrulation.
  
  
  CONCLUSIONS
  Our results indicate that Toll signals are the initiating event in dorso-ventral patterning during Rhodnius embryogenesis, and this is the first report of a conserved role for Toll in a hemipteran. Furthermore, as Rp-dorsal RNA interference generates anteriorly misplaced embryos, our results indicate a novel role for Toll signals in establishment of the anterior-posterior axis in Rhodnius.
authors.affiliation: Instituto de Ciências Biomédicas (ICB), Universidade Federal doRio de Janeiro, Av. Carlos Chagas Filho 373, Ilha do Fundão., Rio de Janeiro, 21941-902 RJ Brazil ; Institute of Molecular Entomology, INCT-INEM, National Institutes in Science and Technology, Macaé, Brazil ; Post-graduate Program in Morphological Sciences, Federal University of Rio de Janeiro (PCM/UFRJ), Rio de Janeiro, RJ Brazil.
authors.forename: Mateus
authors.initials: M
authors.lastname: Berni
authors.affiliation: Instituto de Ciências Biomédicas (ICB), Universidade Federal doRio de Janeiro, Av. Carlos Chagas Filho 373, Ilha do Fundão., Rio de Janeiro, 21941-902 RJ Brazil ; Institute of Molecular Entomology, INCT-INEM, National Institutes in Science and Technology, Macaé, Brazil.
authors.forename: Marcio Ribeiro
authors.initials: MR
authors.lastname: Fontenele
authors.affiliation: Institute of Molecular Entomology, INCT-INEM, National Institutes in Science and Technology, Macaé, Brazil ; Laboratório Integrado de Bioquímica Hatisaburo Masuda, Núcleo de Pesquisas Ecológicas de Macaé (NUPEM), Universidade Federal do Rio de Janeiro (UFRJ), Campus Macaé, Av. São José do Barreto, 764, 27937-450 Macaé, RJ, Brazil.
authors.forename: Vitoria
authors.initials: V
authors.lastname: Tobias-Santos
authors.affiliation: Institute of Molecular Entomology, INCT-INEM, National Institutes in Science and Technology, Macaé, Brazil ; Laboratório Integrado de Bioquímica Hatisaburo Masuda, Núcleo de Pesquisas Ecológicas de Macaé (NUPEM), Universidade Federal do Rio de Janeiro (UFRJ), Campus Macaé, Av. São José do Barreto, 764, 27937-450 Macaé, RJ, Brazil.
authors.forename: Aline
authors.initials: A
authors.lastname: Caceres-Rodrigues
authors.affiliation: Institute of Molecular Entomology, INCT-INEM, National Institutes in Science and Technology, Macaé, Brazil ; Laboratório Integrado de Bioquímica Hatisaburo Masuda, Núcleo de Pesquisas Ecológicas de Macaé (NUPEM), Universidade Federal do Rio de Janeiro (UFRJ), Campus Macaé, Av. São José do Barreto, 764, 27937-450 Macaé, RJ, Brazil.
authors.forename: Flavia Borges
authors.initials: FB
authors.lastname: Mury
authors.affiliation: Institute of Molecular Entomology, INCT-INEM, National Institutes in Science and Technology, Macaé, Brazil ; Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Raquel
authors.initials: R
authors.lastname: Vionette-do-Amaral
authors.affiliation: Institute of Molecular Entomology, INCT-INEM, National Institutes in Science and Technology, Macaé, Brazil ; Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Hatisaburo
authors.initials: H
authors.lastname: Masuda
authors.affiliation: Institute of Molecular Entomology, INCT-INEM, National Institutes in Science and Technology, Macaé, Brazil ; Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Marcos
authors.initials: M
authors.lastname: Sorgine
authors.affiliation: Institute of Molecular Entomology, INCT-INEM, National Institutes in Science and Technology, Macaé, Brazil ; Laboratório Integrado de Bioquímica Hatisaburo Masuda, Núcleo de Pesquisas Ecológicas de Macaé (NUPEM), Universidade Federal do Rio de Janeiro (UFRJ), Campus Macaé, Av. São José do Barreto, 764, 27937-450 Macaé, RJ, Brazil.
authors.forename: Rodrigo Nunes
authors.initials: RN
authors.lastname: da Fonseca
authors.affiliation: Instituto de Ciências Biomédicas (ICB), Universidade Federal doRio de Janeiro, Av. Carlos Chagas Filho 373, Ilha do Fundão., Rio de Janeiro, 21941-902 RJ Brazil ; Institute of Molecular Entomology, INCT-INEM, National Institutes in Science and Technology, Macaé, Brazil.
authors.forename: Helena
authors.initials: H
authors.lastname: Araujo
keywords: Dorso-ventral axis; Embryogenesis; Hemipteran; NFκB; Toll