TBX3 is essential for establishment of the posterior boundary of anterior genes and upregulation of posterior genes together with HAND2 during the onset of limb bud development.

During limb bud formation, axis polarities are established as evidenced by the spatially restricted expression of key regulator genes. In particular, the mutually antagonistic interaction between the GLI3 repressor and HAND2 results in distinct and non-overlapping anterior-distal Gli3 and posterior Hand2 expression domains. This is a hallmark of the establishment of antero-posterior limb axis polarity, together with spatially restricted expression of homeodomain and other transcriptional regulators. Here, we show that TBX3 is required for establishment of the posterior expression boundary of anterior genes in mouse limb buds. ChIP-seq and differential gene expression analysis of wild-type and mutant limb buds identifies TBX3-specific and shared TBX3-HAND2 target genes. High sensitivity fluorescent whole-mount in situ hybridisation shows that the posterior expression boundaries of anterior genes are positioned by TBX3-mediated repression, which excludes anterior genes such as Gli3, Alx4, Hand1 and Irx3/5 from the posterior limb bud mesenchyme. This exclusion delineates the posterior mesenchymal territory competent to establish the Shh-expressing limb bud organiser. In turn, HAND2 is required for Shh activation and cooperates with TBX3 to upregulate shared posterior identity target genes in early limb buds.

Adaptations in energy metabolism and gene family expansions revealed by comparative transcriptomics of three Chagas disease triatomine vectors.

BACKGROUND: Chagas disease is a parasitic infection caused by Trypanosoma cruzi. It is an important public health problem affecting around seven to eight million people in the Americas. A large number of hematophagous triatomine insect species, occupying diverse natural and human-modified ecological niches transmit this disease. Triatomines are long-living hemipterans that have evolved to explode different habitats to associate with their vertebrate hosts. Understanding the molecular basis of the extreme physiological conditions including starvation tolerance and longevity could provide insights for developing novel control strategies. We describe the normalized cDNA, full body transcriptome analysis of three main vectors in North, Central and South America, Triatoma pallidipennis, T. dimidiata and T. infestans. RESULTS: Two-thirds of the de novo assembled transcriptomes map to the Rhodnius prolixus genome and proteome. A Triatoma expansion of the calycin family and two types of protease inhibitors, pacifastins and cystatins were identified. A high number of transcriptionally active class I transposable elements was documented in T. infestans, compared with T. dimidiata and T. pallidipennis. Sequence identity in Triatoma-R. prolixus 1:1 orthologs revealed high sequence divergence in four enzymes participating in gluconeogenesis, glycogen synthesis and the pentose phosphate pathway, indicating high evolutionary rates of these genes. Also, molecular evidence suggesting positive selection was found for several genes of the oxidative phosphorylation I, III and V complexes. CONCLUSIONS: Protease inhibitors and calycin-coding gene expansions provide insights into rapidly evolving processes of protease regulation and haematophagy. Higher evolutionary rates in enzymes that exert metabolic flux control towards anabolism and evidence for positive selection in oxidative phosphorylation complexes might represent genetic adaptations, possibly related to prolonged starvation, oxidative stress tolerance, longevity, and hematophagy and flight reduction. Overall, this work generated novel hypothesis related to biological adaptations to extreme physiological conditions and diverse ecological niches that sustain Chagas disease transmission.

Spatial regulation by multiple Gremlin1 enhancers provides digit development with cis-regulatory robustness and evolutionary plasticity.

Precise cis-regulatory control of gene expression is essential for normal embryogenesis and tissue development. The BMP antagonist Gremlin1 (Grem1) is a key node in the signalling system that coordinately controls limb bud development. Here, we use mouse reverse genetics to identify the enhancers in the Grem1 genomic landscape and the underlying cis-regulatory logics that orchestrate the spatio-temporal Grem1 expression dynamics during limb bud development. We establish that transcript levels are controlled in an additive manner while spatial regulation requires synergistic interactions among multiple enhancers. Disrupting these interactions shows that altered spatial regulation rather than reduced Grem1 transcript levels prefigures digit fusions and loss. Two of the enhancers are evolutionary ancient and highly conserved from basal fishes to mammals. Analysing these enhancers from different species reveal the substantial spatial plasticity in Grem1 regulation in tetrapods and basal fishes, which provides insights into the fin-to-limb transition and evolutionary diversification of pentadactyl limbs.

Nezara viridula (Hemiptera: Pentatomidae) transcriptomic analysis and neuropeptidomics.

Stinkbugs (Hemiptera: Pentatomidae) are of major economic importance as pest of crops. Among the species composing the stinkbug complex, Nezara viridula is one of the most abundant in Brazil, Argentina and the Southern USA. However, this species has been poorly characterized at the genetic and physiological level. Here we sequenced and analyzed the complete transcriptome of N. viridula male and female adults. We identified neuropeptide precursor genes and G-protein coupled receptors for neuropeptides in this transcriptome. Mature neuropeptides were identified in N. viridula brain extracts by liquid chromatography-tandem mass spectrometry. We also analyzed the neuropeptide precursor complement in the genome sequence of Halyomorpha halys, another pentatomid of economic relevance. We compared the results in both pentatomids with the well-characterized neuropeptide repertoire from the kissing bug Rhodnius prolixus (Hemiptera: Reduviidae). We identified both group-specific features (which could be related to the different feeding habits) and similarities that could be characteristic of Heteroptera. This work contributes to a deeper knowledge of the genetic information of these pests, with a focus on neuroendocrine system characterization.

Comparative and functional triatomine genomics reveals reductions and expansions in insecticide resistance-related gene families.

BACKGROUND: Triatomine insects are vectors of Trypanosoma cruzi, a protozoan parasite that is the causative agent of Chagas' disease. This is a neglected disease affecting approximately 8 million people in Latin America. The existence of diverse pyrethroid resistant populations of at least two species demonstrates the potential of triatomines to develop high levels of insecticide resistance. Therefore, the incorporation of strategies for resistance management is a main concern for vector control programs. Three enzymatic superfamilies are thought to mediate xenobiotic detoxification and resistance: Glutathione Transferases (GSTs), Cytochromes P450 (CYPs) and Carboxyl/Cholinesterases (CCEs). Improving our knowledge of key triatomine detoxification enzymes will strengthen our understanding of insecticide resistance processes in vectors of Chagas' disease. METHODS AND FINDINGS: The discovery and description of detoxification gene superfamilies in normalized transcriptomes of three triatomine species: Triatoma dimidiata, Triatoma infestans and Triatoma pallidipennis is presented. Furthermore, a comparative analysis of these superfamilies among the triatomine transcriptomes and the genome of Rhodnius prolixus, also a triatomine vector of Chagas' disease, and other well-studied insect genomes was performed. The expression pattern of detoxification genes in R. prolixus transcriptomes from key organs was analyzed. The comparisons reveal gene expansions in Sigma class GSTs, CYP3 in CYP superfamily and clade E in CCE superfamily. Moreover, several CYP families identified in these triatomines have not yet been described in other insects. Conversely, several groups of insecticide resistance related enzymes within each enzyme superfamily are reduced or lacking in triatomines. Furthermore, our qRT-PCR results showed an increase in the expression of a CYP4 gene in a T. infestans population resistant to pyrethroids. These results could point to an involvement of metabolic detoxification mechanisms on the high levels of pyrethroid resistance detected in triatomines from the Gran Chaco ecoregion. CONCLUSIONS AND SIGNIFICANCE: Our results help to elucidate the potential insecticide resistance mechanisms in vectors of Chagas' disease and provide new relevant information for this field. This study shows that metabolic resistance might be a contributing cause of the high pyrethroid resistance observed in wild T. infestans populations from the Gran Chaco ecoregion, area in which although subjected to intense pyrethroid treatments, vector control has failed. This study opens new avenues for further functional studies on triatomine detoxification mechanisms.

Condiciones y ambiente de trabajo en dos centros de acopio de materiales reciclables del Area Metropolitana de Buenos Aires / Conditions and Environment of Work in Two Recycling Centers in the Metropolitan Area of Buenos Aires

INTRODUCCIÓN: Las plantas de clasificación de residuos aparecen como una alternativa de inserción para los cartoneros. No obstante, se advierten falencias que producen efectos perjudiciales sobre la salud y el ambiente laboral de estos trabajadores no clásicos. OBJETIVOS: Describir el proceso, las condiciones y el medio ambiente de trabajo en centros de acopio y separación de reciclables en el Área Metropolitana de Buenos Aires (AMBA), evaluando las exigencias físicas y el riesgo sanitario. MÉTODOS: Se realizó un estudio descriptivo en dos establecimientos del AMBA, uno en contexto urbano y el otro en descampado periurbano. Se efectuó trabajo de campo etnográfico con observación, entrevistas y dinámicas grupales con técnicas proyectivas y eutonía, en paralelo con muestreos biológicos. RESULTADOS: Se identificaron situaciones externas de riesgo y otras propias del trabajador definidas como exigencias. No se encontraron virus, aunque sí vectores de dengue y encefalitis San Luis. Existe circulación de parásitos con reservorio en roedores, perros y gatos. Se documentaron otros riesgos asociados a residuos industriales, deficiente provisión de agua e incendio. Se registró sobrecarga sobre los trabajadores varones. CONCLUSIONES: Se sugiere vigilancia sanitaria en perros, gatos, roedores e insectos, así como muestreo aleatorio de materiales ingresados. Para reducir exigencias se indica rotación entre puestos y uso de máquinas simples.

INTRODUCTION: Recycling centers appear as an alternative for the employability of informal garbage collectors. However, there are deficiencies producing harmful effects on human health and the labor environment of these non-conventional workers. OBJECTIVES: To describe the process, conditions and environment of work of recycling centers in the Metropolitan Area of Buenos Aires (MABA), evaluating physical demands and health risk. METHODS: A descriptive study was conducted in two recycling facilities located in the MABA, one in an urban setting and the other one in a peri-urban area. Ethnographic fieldwork was carried out with observation, interviews and group dynamics with projective techniques and eutony, in parallel with biological sampling. RESULTS: External risk situations were identified, along with other worker-related factors defined as demands. No viruses were found, although there are vectors of dengue and Saint Louis encephalitis. There is also circulation of parasites with reservoir in rodents, dogs and cats. Other risks associated with industrial waste, poor water supply and fire were documented. There was an overload on male workers. CONCLUSIONS: Sanitary surveillance is suggested in dogs, cats, rodents and insects, as well as random sampling of incoming materials. Job rotation and use of simple machines are indicated to reduce demands.

Condiciones y ambiente de trabajo en dos centros de acopio de materiales reciclables del Area Metropolitana de Buenos Aires / Conditions and Environment of Work in Two Recycling Centers in the Metropolitan Area of Buenos Aires

INTRODUCCIÓN: Las plantas de clasificación de residuos aparecen como una alternativa de inserción para los cartoneros. No obstante, se advierten falencias que producen efectos perjudiciales sobre la salud y el ambiente laboral de estos trabajadores no clásicos. OBJETIVOS: Describir el proceso, las condiciones y el medio ambiente de trabajo en centros de acopio y separación de reciclables en el Área Metropolitana de Buenos Aires (AMBA), evaluando las exigencias físicas y el riesgo sanitario. MÉTODOS: Se realizó un estudio descriptivo en dos establecimientos del AMBA, uno en contexto urbano y el otro en descampado periurbano. Se efectuó trabajo de campo etnográfico con observación, entrevistas y dinámicas grupales con técnicas proyectivas y eutonía, en paralelo con muestreos biológicos. RESULTADOS: Se identificaron situaciones externas de riesgo y otras propias del trabajador definidas como exigencias. No se encontraron virus, aunque sí vectores de dengue y encefalitis San Luis. Existe circulación de parásitos con reservorio en roedores, perros y gatos. Se documentaron otros riesgos asociados a residuos industriales, deficiente provisión de agua e incendio. Se registró sobrecarga sobre los trabajadores varones. CONCLUSIONES: Se sugiere vigilancia sanitaria en perros, gatos, roedores e insectos, así como muestreo aleatorio de materiales ingresados. Para reducir exigencias se indica rotación entre puestos y uso de máquinas simples