Dynamics of maternal gene expression in Rhodnius prolixus

The study of the developmental processes in Rhodnius prolixus has recently advanced with the sequencing of the genome. In this work, we study maternal gene expression driving oogenesis and early embryogenesis in R. prolixus. We analyze the transcriptional profile of mRNAs to establish the genes expressed across the ovary, unfertilized eggs and different embryonic stages of R. prolixus until the formation of the germ band anlage (0, 12, 24, and 48 hours post egg laying). We identified 81 putative maternal and ovary-related genes and validated their expression by qRT-PCR. Consistent with a role in oogenesis and early development of R. prolixus, we show that parental RNAi against Rp-BicD results in embryos that did not show any distinguishable embryonic structure. In this framework we propose three hierarchies of maternal genes that affect early and late oogenesis, and embryonic patterning.Fil: Pascual, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Centro de Bioinvestigaciones (Sede Pergamino); ArgentinaFil: Rivera Pomar, Rolando. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Centro de Bioinvestigaciones (Sede Pergamino); Argentina. Universidad Nacional de La Plata. Centro Regional de Estudios Genómicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

L925I mutation in the Para-type sodium channel is associated with pyrethroid resistance in Triatoma infestans from the Gran Chaco region

Background: Chagas' disease is an important public health concern in Latin America. Despite intensive vector control efforts using pyrethroid insecticides, the elimination of Triatoma infestans has failed in the Gran Chaco, an ecoregion that extends over Argentina, Paraguay, Bolivia and Brazil. The voltage-gated sodium channel is the target site of pyrethroid insecticides. Point mutations in domain II region of the channel have been implicated in pyrethroid resistance of several insect species. Methods and Findings: In the present paper, we identify L925I, a new pyrethroid resistance-conferring mutation in T. infestans. This mutation has been found only in hemipterans. In T. infestans, L925I mutation occurs in a resistant population from the Gran Chaco region and is associated with inefficiency in the control campaigns. We also describe a method to detect L925I mutation in individuals from the field. Conclusions and Significance: The findings have important implications in the implementation of strategies for resistance management and in the rational design of campaigns for the control of Chagas' disease transmission.Fil: Capriotti, Natalia. Universidad Nacional de La Plata. Centro Regional de Estudios Genómicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mougabure Cueto, Gastón Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; ArgentinaFil: Rivera Pomar, Rolando. Universidad Nacional de La Plata. Centro Regional de Estudios Genómicos; Argentina. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Departamento de Ciencias Básicas y Experimentales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ons, Sheila. Universidad Nacional de La Plata. Centro Regional de Estudios Genómicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

An Insight into the Transcriptome of the Digestive Tract of the Bloodsucking Bug, Rhodnius prolixus

The bloodsucking hemipteran Rhodnius prolixus is a vector of Chagas' disease, which affects 7-8 million people today in Latin America. In contrast to other hematophagous insects, the triatomine gut is compartmentalized into three segments that perform different functions during blood digestion. Here we report analysis of transcriptomes for each of the segments using pyrosequencing technology. Comparison of transcript frequency in digestive libraries with a whole-body library was used to evaluate expression levels. All classes of digestive enzymes were highly expressed, with a predominance of cysteine and aspartic proteinases, the latter showing a significant expansion through gene duplication. Although no protein digestion is known to occur in the anterior midgut (AM), protease transcripts were found, suggesting secretion as pro-enzymes, being possibly activated in the posterior midgut (PM). As expected, genes related to cytoskeleton, protein synthesis apparatus, protein traffic, and secretion were abundantly transcribed. Despite the absence of a chitinous peritrophic membrane in hemipterans - which have instead a lipidic perimicrovillar membrane lining over midgut epithelia - several gut-specific peritrophin transcripts were found, suggesting that these proteins perform functions other than being a structural component of the peritrophic membrane. Among immunity-related transcripts, while lysozymes and lectins were the most highly expressed, several genes belonging to the Toll pathway - found at low levels in the gut of most insects - were identified, contrasting with a low abundance of transcripts from IMD and STAT pathways. Analysis of transcripts related to lipid metabolism indicates that lipids play multiple roles, being a major energy source, a substrate for perimicrovillar membrane formation, and a source for hydrocarbons possibly to produce the wax layer of the hindgut. Transcripts related to amino acid metabolism showed an unanticipated priority for degradation of tyrosine, phenylalanine, and tryptophan. Analysis of transcripts related to signaling pathways suggested a role for MAP kinases, GTPases, and LKBP1/AMP kinases related to control of cell shape and polarity, possibly in connection with regulation of cell survival, response of pathogens and nutrients. Together, our findings present a new view of the triatomine digestive apparatus and will help us understand trypanosome interaction and allow insights into hemipteran metabolic adaptations to a blood-based diet.La lista completa de autores que integran el documento puede consultarse en el archivo.Facultad de Ciencias Exacta

An Insight into the Transcriptome of the Digestive Tract of the Bloodsucking Bug, Rhodnius prolixus

The bloodsucking hemipteran Rhodnius prolixus is a vector of Chagas' disease, which affects 7-8 million people today in Latin America. In contrast to other hematophagous insects, the triatomine gut is compartmentalized into three segments that perform different functions during blood digestion. Here we report analysis of transcriptomes for each of the segments using pyrosequencing technology. Comparison of transcript frequency in digestive libraries with a whole-body library was used to evaluate expression levels. All classes of digestive enzymes were highly expressed, with a predominance of cysteine and aspartic proteinases, the latter showing a significant expansion through gene duplication. Although no protein digestion is known to occur in the anterior midgut (AM), protease transcripts were found, suggesting secretion as pro-enzymes, being possibly activated in the posterior midgut (PM). As expected, genes related to cytoskeleton, protein synthesis apparatus, protein traffic, and secretion were abundantly transcribed. Despite the absence of a chitinous peritrophic membrane in hemipterans - which have instead a lipidic perimicrovillar membrane lining over midgut epithelia - several gut-specific peritrophin transcripts were found, suggesting that these proteins perform functions other than being a structural component of the peritrophic membrane. Among immunity-related transcripts, while lysozymes and lectins were the most highly expressed, several genes belonging to the Toll pathway - found at low levels in the gut of most insects - were identified, contrasting with a low abundance of transcripts from IMD and STAT pathways. Analysis of transcripts related to lipid metabolism indicates that lipids play multiple roles, being a major energy source, a substrate for perimicrovillar membrane formation, and a source for hydrocarbons possibly to produce the wax layer of the hindgut. Transcripts related to amino acid metabolism showed an unanticipated priority for degradation of tyrosine, phenylalanine, and tryptophan. Analysis of transcripts related to signaling pathways suggested a role for MAP kinases, GTPases, and LKBP1/AMP kinases related to control of cell shape and polarity, possibly in connection with regulation of cell survival, response of pathogens and nutrients. Together, our findings present a new view of the triatomine digestive apparatus and will help us understand trypanosome interaction and allow insights into hemipteran metabolic adaptations to a blood-based diet.La lista completa de autores que integran el documento puede consultarse en el archivo.Facultad de Ciencias Exacta

Cytoplasmic Ribonucleoprotein Foci in Eukaryotes: Hotspots of Bio(chemical)Diversity

The life of an mRNA from transcription to degradation offers multiple control check points that regulate gene expression. Transcription, splicing, and translation have been widely studied for many years; however, in recent years, new layers of posttranscriptional and posttranslational control have been uncovered. They involve the regulation of the metabolism of mRNA in cytoplasmic foci. They are collections of ribonucleoprotein complexes that, in most cases, remain still uncharacterized, except the processing bodies (PBs) and stress granules (SGs), which have been studied (and reviewed) in detail. A challenging prospective is to know how many different classes of foci exist, which functions they support, how are they formed, and how do they relate one to each other. Here, we present an update of the component of the different granules, a possible function, and hypothesis on their in vivo dynamics related to translational control

The neuropeptidome of Rodhnius Prolixus brain

Comunicaciones a congreso

Cooperative DNA-binding by Bicoid provides a mechanism for threshold-dependent gene activation in the Drosophila embryo

The Bicoid morphogen directs pattern formation along the anterior-posterior (A-P) axis of the Drosophila embryo. Bicoid is distributed in a concentration gradient that decreases exponentially from the anterior pole, however, it transcribes target genes such as hunchback in a step-function-like pattern; the expression domain is uniform and has a sharply defined posterior boundary. A 'gradient-affinity' model proposed to explain Bicoid action states that (i) cooperative gene activation by Bicoid generates the sharp on/off switch for target gene transcription and (ii) target genes with different affinities for Bicoid are expressed at different positions along the A-P axis. Using an in vivo yeast assay and in vitro methods, we show that Bicoid binds DNA with pairwise cooperativity; Bicoid bound to a strong site helps Bicoid bind to a weak site. These results support the first aspect of the model, providing a mechanism by which Bicoid generates sharp boundaries of gene expression. However, contrary to the second aspect of the model, we find no significant difference between the affinity of Bicoid for the anterior gene hunchback and the posterior gene knirps, We propose, instead, that the arrangement of Bicoids bound to the target gene presents a unique signature to the transcription machinery that, in combination with overall affinity, regulates the extent of gene transcription along the A-P axis

Nota corta. Patógenos telúricos aislados de planta de judía (Phaseolus vulgaris L.) con síntomas de mal de pie en Galicia

Pathogens belonging to the disease complex responsible for bean collar and root rots in northwest Spain were identified and their pathogenic behaviour studied over a two year period (2004-2005). The potential fungal and oomycete pathogens Fusarium solani f. sp. phaseoli (Burkh.) W.C. Snyder and Hansen, Rhizoctonia solani Kühn, Pythium ultimum Trow, Pythium Group G, Fusarium avenaceum (Fr.) Sacc., F. culmorum W. G. Sm. (Sacc.), Botrytis cinerea Pers., Sclerotinia sclerotiorum (Lib.) de Bary and Sclerotium rolfsii Sacc. were isolated from 419 bean (Phaseolus vulgaris L.) plants affected by collar or root rot. Fusarium solani f. sp. phaseoli was the most frequently isolated (found on 63.7% of the farms surveyed and isolated from 19.3% of the diseased plants), followed by R. solani and the Pythium species. Inoculating Phaseolus vulgaris cv. Música and Zondra with 14 isolates of these fungi and oomycetes showed F. solani f. sp. phaseoli to be the most aggressive pathogen of the complex; F. avenaceum and F. culmorum were found not to be pathogenic for either cultivar. The results confirm that F. solani and R. solani are the main pathogens of the bean collar/root rot disease complex in northwest Spain, affecting crops in their early growth stages. The complex also includes P. ultimum and Pythium Group G.Durante los años 2004 y 2005 se llevó a cabo en Galicia la identificación de los patógenos que formaban parte del complejo parasitario responsable del mal de pie en el cultivo de la judía, así como la evaluación de su poder patógeno. Los hongos y oomicetos patógenos potenciales aislados sobre un total de 419 plantas de judía (Phaseolus vulgaris L.) con síntomas de mal de pie, muestreados durante dicho período en Galicia, fueron los siguientes: Fusarium solani f. sp. phaseoli (Burkh.)W.C. Snyder y Hansen, Rhizoctonia solani Kühn, Pythium ultimum Trow, Pythium Grupo G, Fusarium avenaceum (Fr.) Sacc., F. culmorum W. G. Sm. (Sacc.), Botrytis cinerea Pers., Sclerotinia sclerotiorum (Lib.) de Bary y Sclerotium rolfsii Sacc. El patógeno más frecuentemente aislado fue F. solani f. sp. phaseoli, detectado en el 63,7% de las explotaciones muestreadas, así como en el 19,3% de las plantas analizadas, seguido de R. solani y de Pythium spp. Las pruebas de inoculación de 14 aislamientos de estos hongos y oomicetos sobre las variedades de judía Música y Zondra indicaron que F. solani f. sp phaseoli posee el mayor poder patógeno, mientras que F. avenaceum y F. culmorum no resultaron ser patogénicos sobre ninguna de las dos variedades inoculadas. Los resultados de este trabajo confirman que F. solani y R. solani son los principales patógenos responsables del mal de pie de la judía en Galicia, complejo parasitario que incluye también a P. ultimum y P. Grupo G en los primeros estadíos del cultivo

The gap gene Krüppel of Rhodnius prolixus is required for segmentation and for repression of the homeotic gene sex comb-reduced

AbstractThe establishment of the anterior–posterior segmentation in insects requires the concerted action of a hierarchical gene network. Here, we study the orthologue of Krüppel gap gene in the hemipteran Rhodnius prolixus (Rp-Kr). We characterized its structure, expression pattern and function. The genomic sequence upstream of the Rp-Kr transcriptional unit shows a putative regulatory region conserved in the orthologue genes from Drosophila melanogaster and Tribolium castaneum. Rp-Kr expression is zygotic and it is expressed in the anterior half of the embryo (the posterior half of the egg) during the blastoderm stage and germ band formation; later, during germ band extension, it is expressed in a central domain, from T2 to A3. The Rp-Kr loss of function phenotypes shows disrupted thoracic and abdominal segmentation. Embryos with weak segmentation phenotypes show homeotic transformations, in which an ectopic tibial comb, typical of T1 leg, appears in T2, which correlates with the ectopic expression of Rp-sex-comb reduced in this leg

L925I Mutation in the Para-Type Sodium Channel Is Associated with Pyrethroid Resistance in Triatoma infestans from the Gran Chaco Region

Background:Chagas' disease is an important public health concern in Latin America. Despite intensive vector control efforts using pyrethroid insecticides, the elimination of Triatoma infestans has failed in the Gran Chaco, an ecoregion that extends over Argentina, Paraguay, Bolivia and Brazil.The voltage-gated sodium channel is the target site of pyrethroid insecticides. Point mutations in domain II region of the channel have been implicated in pyrethroid resistance of several insect species.Methods and Findings:In the present paper, we identify L925I, a new pyrethroid resistance-conferring mutation in T. infestans. This mutation has been found only in hemipterans. In T. infestans, L925I mutation occurs in a resistant population from the Gran Chaco region and is associated with inefficiency in the control campaigns. We also describe a method to detect L925I mutation in individuals from the field.Conclusions and Significance:The findings have important implications in the implementation of strategies for resistance management and in the rational design of campaigns for the control of Chagas' disease transmission.Facultad de Ciencias Exacta