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

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

A propósito de un pedido de "juicio académico" en la UNLP, ¿represión o censura?

Se cuestiona el pedido de juicio académico al profesor y diputado nacional Martin Tetaz por declaraciones realizadas acerca del atentado contra la vicepresidente de la Nacion Cristina Elizabet Fernández. Se cuestiona el pedido de un conjunto de docentes, graduados y alumnos de la Facultad de Ciencias Jurídicas y Sociales de la UNLP, de juicio académico, hecho que se considera contrario a las normas universitarias y censura a la libertad de expresión.Universidad Nacional de La Plat

Non-Muscle Myosin IIA (Myh9) is in the Nucleus of S-Phase Entering NT2-D1 Cells

Non-muscle myosin IIA is a cytoplasmic protein that works in concert with F-actin to produce cell movement. The heavy chain of this protein is codified by the MYH9 gene. The presence of motor proteins as myosin or mono and F-actin and their role in transcription has recently been observed. Prep1–the transcription factor of HOXB genes– constitutes a dimer with Pbx1, which induces HOXB gene expression. Prep1 has been found purifying with β-actin and Myh9. HOXB transcription initiates when cells enter in S-phase, during which DNA duplication and transcription occur at the same time. Here, we have shown that Myh9 co-localizes with Prep1 in the nucleus and in the periphery of the nucleolus in S-phase NT2-D1 cells. Furthermore, we have shown that Myh9 purifies with Pbx1 from nuclear extracts of S-phase entering NT2-D1 cells –and not from cytoplasmic extracts. Taking into account these results, we conclude that Myh9 is in the nucleus of the S-phase entering NT2-D1 cells and might have a role in HOXB transcription.Centro Regional de Estudios Genómico

Nuclear actin polymerization from faster growing ends in the initial activation of hox gene transcription : Are nuclear speckles involved?

The HoxB cluster expression is activated by retinoic acid and transcribed in a collinear manner. The DNA-binding Pknox1-Pbx1 complex modulates Hox protein activity. Here, NT2-D1 teratocarcinoma cells -a model of Hox gene expression- were used to show that upon retinoic acid induction, Pknox1 co-localizes with polymeric nuclear actin. We have found that globular actin aggregates, polymeric actin, the elongating RNA polymerase II and THOC match euchromatic regions corresponding to nuclear speckles. Moreover, RNA polymerase II, N-WAS P, and transcription/splicing factors p54nrb and PSF were validated as Pknox1 interactors by tandem affinity purification. PSF pulled down with THOC and nuclear actin, both of which co-localize in nuclear speckles. Although latrunculin A slightly decreases the general level of HoxB gene expression, inhibition of nuclear actin polymerization by cytochalasin D blocks the expression of HoxB transcripts in a collinear manner. Thus, our results support the hypothesis that nuclear actin polymerization is involved in the activation of HoxB gene expression by means of nuclear speckles.Centro Regional de Estudios Genómico

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

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

Culture–independent characterization of the bacterioplankton community composition of a mesotrophic reservoir (Embalse Río III, Argentina)

Este estudio constituye el primer análisis de la estructura de la comunidad del bacterioplancton en un reservorio de agua dulce de Argentina utilizando amplificación completa del gen ADNr 16S. Incluye las relaciones filogenéticas y una descripción del bacterioplacton de las zonas fótica y afótica del Embalse Río III, Córdoba, Argentina. El análisis ecológico clásico indicó que la zona fótica tenía mayor diversidad, mientras que la afótica tenía mayor abundancia y una distribución más uniforme de especies. Sin embargo, cuando se utilizó la información filogenética para comparar las comunidades microbianas de ambas zonas, este análisis indicó que ambos ambientes eran similares y que en ninguno predominaba algún linaje en particular. Los phyla identificados en el Embalse del Río III fueron Acidobacteria, Actinobacteria y Proteobacteria. Las especies dominantes en ambas zonas fueron "Candidatus Planktophila sp.” (clase Actinobacteria) y Polynucleobacter sp. (clase Betaproteobacteria).This study represents the first analysis of the bacterioplankton community structure from an Argentine freshwater reservoir using amplification of the entire 16S rDNA gene. It includes the description and the phylogenetic relationships of the bacterioplankton community from the photic and aphotic layers of the Río III Reservoir in Córdoba, Argentina. The classical ecological approach indicated that the photic layer showed greater diversity and the aphotic layer a more even distribution of species and higher biomass. Nevertheless, when the microbial communities in both layers were compared using phylogenetic information, this analysis indicated that both environments were similar and that neither was enriched for any particular lineage. The phyla present in the Río III reservoir were Acidobacteria, Actinobacteria and Proteobacteria and the two dominant species in both layers were Candidatus Planktophila sp. (class Actinobacteria) and Polynucleobacter sp. (class Betaproteobacteria).Centro Regional de Estudios GenómicosInstituto de Limnología "Dr. Raúl A. Ringuelet

Culture–independent characterization of the bacterioplankton community composition of a mesotrophic reservoir (Embalse Río III, Argentina)

Este estudio constituye el primer análisis de la estructura de la comunidad del bacterioplancton en un reservorio de agua dulce de Argentina utilizando amplificación completa del gen ADNr 16S. Incluye las relaciones filogenéticas y una descripción del bacterioplacton de las zonas fótica y afótica del Embalse Río III, Córdoba, Argentina. El análisis ecológico clásico indicó que la zona fótica tenía mayor diversidad, mientras que la afótica tenía mayor abundancia y una distribución más uniforme de especies. Sin embargo, cuando se utilizó la información filogenética para comparar las comunidades microbianas de ambas zonas, este análisis indicó que ambos ambientes eran similares y que en ninguno predominaba algún linaje en particular. Los phyla identificados en el Embalse del Río III fueron Acidobacteria, Actinobacteria y Proteobacteria. Las especies dominantes en ambas zonas fueron "Candidatus Planktophila sp.” (clase Actinobacteria) y Polynucleobacter sp. (clase Betaproteobacteria).This study represents the first analysis of the bacterioplankton community structure from an Argentine freshwater reservoir using amplification of the entire 16S rDNA gene. It includes the description and the phylogenetic relationships of the bacterioplankton community from the photic and aphotic layers of the Río III Reservoir in Córdoba, Argentina. The classical ecological approach indicated that the photic layer showed greater diversity and the aphotic layer a more even distribution of species and higher biomass. Nevertheless, when the microbial communities in both layers were compared using phylogenetic information, this analysis indicated that both environments were similar and that neither was enriched for any particular lineage. The phyla present in the Río III reservoir were Acidobacteria, Actinobacteria and Proteobacteria and the two dominant species in both layers were Candidatus Planktophila sp. (class Actinobacteria) and Polynucleobacter sp. (class Betaproteobacteria).Centro Regional de Estudios GenómicosInstituto de Limnología "Dr. Raúl A. Ringuelet