Caracterização molecular de Johnsongrass mosaic virus em plantas forrageiras dos gêneros brachiaria, panicum e pennisetum

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Departamento de Fitopatologia, Programa de Pós-Graduação em Fitopatologia, 2015.Atualmente o Brasil possui o maior rebanho bovino comercial do mundo, somando 210 milhões de cabeças de gado para a produção de carne, leite e seus derivados. Com isso é o maior exportador de carne do mundo e o 2º maior produtor mundial, representando 16% desse comércio. Considerando a produção de leite, o Brasil ocupa a 3º posição no mercado mundial. Tal produção ocorre em 48% das áreas ocupadas com atividades rurais, que são destinadas as pastagens naturais e cultivadas. As principais plantas forrageiras plantadas no Brasil são dos gêneros Panicum, Brachiaria e Pennisetum, pertencentes à família Poaceae que têm como centro de origem e diversidade o continente africano. Plantas com sintomas de vírus, têm sido frequentemente encontradas, principalmente nos bancos de germoplasma da Embrapa Gado de Corte no estado do Mato Grosso do Sul, e da Embrapa Gado de Leite no estado da Bahia. Devido à falta de conhecimento do agente etiológico, o presente trabalho visou a identificação e caracterização de vírus em plantas forrageiras dos gêneros Panicum, Brachiaria e Pennisetum. Utilizando a plataforma de sequenciamento de alto desempenho Illumina, foi identificado o Johnsongrass mosaic virus. Inicialmente foi realizado um sequenciamento a partir de um acesso de Pennisetum. Posteriormente, foi realizado um segundo sequenciamento usando amostra composta de 5 acessos de Panicum e 5 de Brachiaria. Com esses sequenciamentos foram obtidos dois genomas de JGMV, um com 9828 nt de extensão, excluindo a cauda poli (A) originário do sequenciamento de Panicum e Brachiaria (JGMV-BR), e o outro com 9649 nt de extensão excluindo a poli (A) e a região 5ˊUTR, originário do sequenciamento de Pennisetum (JGMV-Penni). A técnica do 5ˊRACE foi usada para o isolamento da região 5ˊUTR, somente para um vírus JGMV-BR. A 3ˊUTR para cada isolado também foi amplificada e sequenciada. As análises da sequência predita de aminoácidos possibilitaram a dedução dos sítios de clivagem, bem como a identificação das sequências e motivos conservados dentro da sequência de cada proteína. As análises de comparações do genoma de cada vírus revelaram identidade da capa proteica de 77% (nt) do isolado JGMV-BR e 78% (nt) do isolado JGMV-Penni com o JGMV australiano (NC_003606). De acordo com o critério de demarcação de espécie para Potyvirus, em que o limiar para a demarcação de espécie é de 76-77% de identidade nucleotídica, os dois isolados de JGMV são uma estirpe da mesma espécie. As árvores filogenéticas geradas utilizando as sequências nucleotídicas e peptídicas da poliproteína revelaram que os dois isolados brasileiros de JGMV são filogeneticamente relacionados com o JGMV australiano, e ambos são relacionados ao Canna yellow streak virus. Além disso, várias espécies que infectam monocotiledôneas formaram um clado, onde JGMV se insere. A partir da sequência consenso do genoma completo de JGMV-BR, foram sintetizados primers específicos que correspondiam ao gene da capa proteica para a detecção de JGMV. Além disso, para avaliar a diversidade genética de JGMV, a partir dos 11 acessos utilizados no NGS, fragmentos gênicos de CP foram clonados e de 3 a 5 clones foram sequenciados para cada acesso avaliado. A matriz de comparação das sequências nucleotídicas da CP comparados com os isolados australianos e americanos variou de 77 a 82% de identidade nucleotídica. A árvore filogenética utilizando a sequência nucleotídica da CP, indica a presença de ao menos duas linhagens de JGMV, uma circulando nos EUA/Austrália e outra no Brasil. Além disso, é possível observar que alguns isolados de vírus foram encontrados em mais de um acesso e determinados acesso demostraram a presença de mais de um isolado. Assim, como resultado deste trabalho, foi realizado o primeiro relato de JGMV no Brasil.Currently, Brazil has the largest commercial herd in the world, totaling 210 million head of cattle, for the production of meat, milk and dairy products. This makes it the largest exporter in the world meat and the 2nd largest producer, accounting for 16% of this trade. Considering milk production, Brazil is ranked 3rd in the world market. This production occurs in 48% of areas occupied by rural activities, which are used natural and cultivated pastures. The main forage crops planted in Brazil are Panicum, Brachiaria and Pennisetum, all belonging to the Poaceae family whose center of origin and diversity is in Africa. Plants with symptoms of virus have often been found, mainly in germoplasm banks Embrapa Beef Cattle in Mato Grosso do Sul, and the Embrapa Dairy Cattle in the state of Bahia. Due to lack of knowledge of the etiologic agent, the present study aimed to identify and characterize viruses in forages of Panicum, Brachiaria and Pennisetum. Using high performance platform Illumina sequencing, was identified Johnsongrass mosaic virus. Initially, sequencing was carried out from a Pennisetum line. A second sequencing was done using 5 of Panicum and 5 of Brachiaria lines. Thus, two genomes were obtained from JGMV, one with 9828 nt in length, excluding the poly (A) tail, from Panicum and Brachiaria (JGMV-BR), and the other with a length of 9649 nt, excluding the poly (A) and the 5ˊUTR region, from Pennisetum (JGMV-Penni). The 5ˊRACE technique was used for isolation of the 5ˊUTR of JGMV-BR. The 3ˊUTR for each isolate was also amplified and sequenced. Analysis of the predicted amino acid sequence permitted the deduction of the cleavage sites and the sequences and identifying the conserved motifs within the sequence of each protein. The genome comparisons analysis of each virus revealed identity of the coat protein of 77% (nt) of JGMV-BR and 78% (nt) of JGMV-Penni with JGMV Australian (NC_003606). According to the demarcation criterion for Potyvirus, where the threshold for species differentiation is 76-77% nucleotide identity, the two JGMV are isolated from a strain of the same species. Phylogenetic trees generated using the nucleotide and peptide sequence of the polyprotein revealed that the two Brazilian isolates of JGMV are phylogenetically related to the Australian JGMV, and both are related to Canna yellow streak virus. In addition, several species that infect monocots formed a clade where JGMV groups. From the consensus sequence of the complete genome of JGMV-BR specific primers were synthesized which corresponded to the gene for the coat protein detection JGMV. Furthermore, to evaluate the genetic diversity of JGMV, from 11 lines used in NGS CP gene fragments were cloned and 3 to 5 clones were sequenced for each lines evaluated. The comparison of the nucleotide sequences of the matrix CP compared with the Australian and American isolates ranged 77-82% nucleotide identity. The phylogenetic tree using the nucleotide sequence of CP indicates the presence of at least two strains of JGMV, one circulating US / Australia and other in Brazil. Furthermore, it is possible to observe that some virus isolates were found in more than one line and certain line demonstrated the presence of more than one isolated. Thus, as a result of this work, we performed the first report of JGMV in Brazil

Pullback attractors for a singularly nonautonomous plate equation

We consider the family of singularly nonautonomous plate equation with structural damping $$u_{tt} + a(t,x)u_{t} + (- \Delta) u_{t} + (-\Delta)^{2} u + \lambda u = f(u),$$ in a bounded domain $\Omega \subset \R^n$, with Navier boundary conditions. When the nonlinearity $f$ is dissipative we show that this problem is globally well posed in $H^2_0(\Omega) \times L^2(\Omega)$ and has a family of pullback attractors which is upper-semicontinuous under small perturbations of the damping $a$

Estudos biológicos e moleculares dos patossistemas Johnsongrass mosaic virus (JGMV) e Maize chlorotic dwarf virus (MCDV) em gramíneas forrageiras

Tese (doutorado)—Universidade de Brasília, Instituto de Ciências Biológicas, Departamento de Biologia Celular, Programa de Pós-Graduação em Biologia Molecular, 2019.O Brasil tem o maior rebanho bovino comercial do mundo, destinado para produção de carne e leite, sendo majoritariamente alimentado com pastagens. A alta incidência de pragas e doenças afeta campos com pastagens, sendo que os agentes biológicos nem sempre são identificados. Sintomas típicos de infecções virais como mosaico, amarelecimento generalizado e nanismo vêm sendo observados em campos experimentais e comerciais de pastagens naturais e cultivadas. Recentemente, nosso grupo de pesquisa identificou duas espécies virais infectando Pennisetum purpureum, Panicum maximum e Brachiaria brizantha por meio do sequenciamento em larga escala (High-Throughput sequencing-HTS): o Johnsongrass mosaic virus (isolado JGMVCNPGL) e o Maize chlorotic dwarf virus (isolado MCDV-BR). A partir dessa identificação preliminar, o objetivo desse trabalho foi realizar a caracterização biológica e molecular desses dois isolados, bem como realizar a localização subcelular das proteínas P1, CP1, CP2 e CP3 do vírus MCDV-BR, tendo em vista que as funções destas proteínas são pouco elucidadas. A caracterização biológica de JGMV-CNPGL e MCDV-BR é fundamental para o desenvolvimento de estratégias de defesa contra esses agentes etiológicos com alto poder de infecção em plantas forrageiras colocando em risco o setor pecuário nacional, entretanto não foi realizada para o MCDV-BR, pois o vírus não passa mecanicamente e o vetor de transmissão não foi identificado. O isolado JGMV-CNPGL, identificado em plantas de P. purpureum, foi inoculado mecanicamente em 14 espécies de plantas indicadoras, sendo que 10 delas foram suscetíveis. O genoma desse vírus possui 9.865 nt, que codifica 11 proteínas (P1, HC-Pro P3, 6K1, CI, 6K2, VPg, NIa, NIb, CP e PIPO). Os valores de identidade de nucleotídeos da capa proteica (CP) e do genoma completo obedecem aos critérios de demarcação de espécie para o gênero Potyvirus. Alguns motivos conservados característicos de Potyvirus foram identificados nas proteínas codificadas por esse vírus, entretanto, o motivo KITC da HC-Pro, envolvido na interação da partícula viral com o estilete do vetor (Afídeo), não está presente. Vale ressaltar que a porção N-terminal da CP mostrou apenas 38% de identidade de sequência de aminoácidos quando comparados com outros isolados de JGMV caracterizados em outras regiões do mundo. As implicações biológicas dessa divergência de sequências precisam ser elucidadas. O genoma de MCDV-BR, encontrado infectando Brachiaria, possui 11.960 nt com uma ORF1 codificando uma poliproteína de 9 proteínas (P1, CP1, CP2, CP3, R37, Hel, R69, 3C-Pro e RdRP) e uma pequena ORFx, interna e próxima da extremidade 5ʹ da ORF1. A comparação de sequência aminoácidos das CPs (CP1, CP2 e CP3) e RdRp (Pol) se encaixa dentro dos critérios de demarcação de espécie para gênero Waikavirus, identificando este isolado como pertencente a espécie MCDV. A localização subcelular de proteínas de MCDV-BR em fusão com eGFP, confirmada por colocalização com marcadores de organelas, demonstrou que a proteína P1 está presente no citoplasma, próximo a parede celular, CP1 é endereçada a mitocôndria, CP2 forma agregados no núcleo e CP3 está no citoplasma próximo a parede celular e também forma agregados no núcleo. Experimentos complementares devem ser realizados para comprovar a localização subcelular, podendo auxiliar na predição de funções das proteínas virais.CAPESBrazil has the largest commercial cattle herd in the world, used for beef and dairy production, being mainly fed on pastures. The high incidence of pests and diseases affects fields with pastures, and biological agents are not always identified. Typical symptoms of viral infections such as mosaic, widespread yellowing and dwarfism have been observed in experimental and commercial fields of natural and cultivated pastures. Our research group recently identified two viral species infecting Pennisetum purpureum, Panicum maximum and Brachiaria brizantha by High-Throughput sequencing: Johnsongrass mosaic virus (JGMV-CNPGL isolate) and Maize chlorotic dwarf virus (MCDV-BR isolate). From this preliminary identification, the objective of this work was to perform the biological and molecular characterization of these two isolates, as well as to perform the subcellular localization of proteins P1, CP1, CP2 and CP3 of the MCDVBR virus. From this preliminary identification, the objective of this work was to carry out the biological and molecular characterization of these two isolates, as well as to perform the subcellular localization of MCDV-BR virus proteins P1, CP1, CP2 and CP3, considering that their functions are poorly understood. The biological characterization of JGMV-CNPGL and MCDV-BR is fundamental for the development of defense strategies against these etiological agents with high potential infection in forage plants putting at risk the national livestock sector. However, characterization of MCDV-BR was not performed, because this virus does not pass mechanically, and the transmission vector was not identified. The JGMV-CNPGL isolate, identified in P. purpureum plants, was mechanically inoculated in 14 host plant candidates, 10 of which were susceptible. The genome of this virus has 9,865 nt, which encodes 11 proteins (P1, HC-Pro, P3, 6K1, CI, 6K2, VPg, NIa, NIb, CP and PIPO). The nucleotide identity values of CP and the complete genome obey the species demarcation criteria for the genus Potyvirus. Some conserved motifs characteristic of Potyvirus have been identified in proteins encoded by this virus, however, the HC-Pro KITC motif, involved in the interaction of the viral particle with the vector stylets (Aphid), is not present. It is noteworthy that the N-terminal portion of CP showed only 38% amino acid sequence identity when compared to other JGMV isolates characterized in other regions of the world. The biological implications of this sequence divergence need to be elucidated. The MCDV-BR virus genome, found infecting Brachiaria, has 11,960 nt with an ORF1 encoding a polyprotein with 9 proteins (P1, CP1, CP2, CP3, R37, Hel, R69, 3C-Pro and RdRP) and a small ORFx, internal and near the 5ʹ end of ORF1. The peptide sequence comparison of the CPs (CP1, CP2 and CP3) and Pol (RdRp) fits within the species demarcation criteria for Waikavirus genus, identifying this isolate as belonging to the MCDV species. The subcellular localization of MCDV-BR proteins fused with eGFP, confirmed by co-localization with organelle markers, demonstrated that protein P1 is present in the cytoplasm, near the cell wall, CP1 is addressed to mitochondria, CP2 forms nucleus aggregates. and CP3 is in the cytoplasm near the cell wall and forms aggregates in the nucleus. However, complementary experiments should be performed to prove subcellular localization, which may aid in the prediction of viral protein functions

Characteristics of a long-stay institution for the elderly

Objective: To evaluate the operation of a Long-Stay Institution for the Elderly (LSIE), aiming adequacy of the LSIE according to legislation and improving care. Methods: A qualitative, exploratory-descriptive, action research study was performed, in Currais Novos/RN. Routine observation, interviews and records were the used ways for data collection. Results: The institution was philanthropic, approaching type II care modality. The elderly were confined mainly by family abandonment. Health team was incomplete, with workload fewer than recommended by law, and the care team worked without coordination and supervision of a nurse. Conclusion: We hope that intervention proposal will contribute to improvements in the LSIE, improving care quality provided to the elderly

Perceptions of brachyfacial, mesofacial and dolichofacial individuals with regard to the buccal corridor in different facial types

Objective: Evaluate the esthetic perception and attractiveness of the smile with regard to the buccal corridor in different facial types by brachyfacial, mesofacial and dolichofacial individuals. Material and Methods: The image of a smiling individual with a mesofacial type of face was changed to create three different facial types with five different buccal corridors (2%, 10%, 15%, 22% and 28%). To achieve this effect, a photo editing software was used (Adobe Photoshop, Adobe Systems Inc, San Francisco, CA, EUA). The images were submitted to evaluators with brachyfacial, mesofacial and dolichofacial types of faces, who evaluated the degree of esthetic perception and attractiveness by means of a visual analog scale measuring 70 mm. The differences between evaluators were verified by the Mann-Whitney test. All statistics were performed with a confidence level of 95%. Results: Brachyfacial individuals perceived mesofacial and dolichofacial types of faces with buccal corridor of 2% as more attractive. Mesofacial individuals perceived mesofacial and dolichofacial types of faces with buccal corridor of 2%, 10% and 15% as more attractive. Dolichofacial individuals perceived the mesofacial type of face with buccal corridor of 2% as more attractive. Evaluators of the female sex generally attributed higher scores than the male evaluators. Conclusion: To achieve an enhanced esthetic smile it is necessary to observe the patient’s facial type. The preference for narrow buccal corridors is an esthetic characteristic preferred by men and women, and wide buccal corridors are less attractive

Dynamics of the loss and emergence of volatile compounds during the concentration of cashew apple juice (Anacardium occidentale L.) and the impact on juice sensory quality

AbstractConcentrating cashew apple juice alters the beverage aroma and flavor, compromising consumer acceptability of the concentrated beverage. To understand the mechanisms involved in these changes, this research characterized the dynamics of the loss and emergence of volatile compounds during cashew apple juice concentration, reporting their impact on beverage sensory quality. Fresh cashew apple juice (10.3°Brix) was concentrated in a thermal-siphon type evaporator operating in a closed system. Five samples were taken throughout the concentration process with the following soluble solids contents: 11.8°Brix, 14.9°Brix, 20.2°Brix, 29.6°Brix and 42.1°Brix. Trained judges rated the aroma note intensities, described as “fresh cashew apple” and “cooked” as perceived in the fresh and concentrated beverages. The headspace volatiles of the six samples were identified and quantified by GC–MS. The results indicated the esters as the major component in the fresh juice (226.46μgkg−1) representing 45.0% of the total mass of volatiles, followed by the terpenes (118.98μgkg−1), acids (45.23μgkg−1), aldehydes (39.10μgkg−1), alcohols (18.91μgkg−1), lactones (19.15μgkg−1), hydrocarbons (18.02μgkg−1) and ketones (11.05μgkg−1). Predictive statistical models (R2>0.956, p≤0.002) revealed that on reaching 14.9°Brix, the ester concentration declined more than 90%, the terpene content almost 100%, alcohols 85%, aldehydes 80% and hydrocarbons 90%. At 14.9°Brix, the intensity of “fresh cashew apple” aroma still predominated in the juice, but the panelists detected the presence of a weak “cooked” aroma. Concentration of the beverage to 20.2°Brix or above expressively increased the cooked aroma intensity and the concentration of hydrocarbons, alcohols and some aldehydes usually associated with off-flavors such as pentanal and decanal. This raises the possibility that some of these compounds might have been formed during juice processing. Juice with better sensory quality could possibly be obtained by concentrating the beverage to levels below 20.2°Brix, recovering the esters that evaporated off the juice until ~15°Brix is reached, and re-adding them to the juice concentrated

Prevalência, severidade e fatores associados à depressão em estudantes universitários

Objetivo: identificar a prevalência, a severidade e os fatores associados à depressão entre estudantes universitários no Distrito Federal. Método: estudo transversal realizado com 521 estudantes universitários, com idade entre 18 e 60 anos. Os sintomas depressivos foram avaliados através da escala Patient Health Questionnaire-9 (PHQ-9). Utilizou-se estatística descritiva e o teste do qui-quadrado. Resultados: dentre os 521 indivíduos estudados, houve predomínio do sexo feminino. A prevalência de sintomas depressivos foi de 521 (96,6%) estudantes universitários, sendo 31,3% com depressão suave, 23,4%, depressão mínima,  13,1% depressão moderadamente grave, 9,6% depressão grave e 9,2% depressão moderada. A renda familiar e o semestre cursado são fatores associados para a severidade da depressão. Conclusão: a prevalência da depressão no ambiente  universitário é comum, sendo uma proporção alta e preocupante. É crucial o rastreamento da depressão, sua severidade e seus fatores associados, a fim de estimular reflexão sobre a temática e pensar em estratégias de intervenção para a prevenção e promoção da saúde mental.Descritores: to identify the prevalence, severity and factors associated with depression among university students in the Federal District. Method: a cross-sectional study carried out with 521 university students, aged between 18 and 60 years old. Depressive symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9) scale. Descriptive statistics and the chi-square test were used. Results: among the 521 individuals studied, there was predominance of females. The prevalence of depressive symptoms was 521 (96.6%) university students; 31.3% with mild depression; 23.4%, minimal depression, 13.1%, moderately severe depression; 9.6%, severe depression; and 9.2%, moderate depression. Family income and the semester attended are associated factors for the severity of depression. Conclusion: the prevalence of depression in the university environment is common, being at a  high and worrying proportion. It is crucial to track depression, its severity and its associated factors, in order to stimulate reflection on the theme and to think of intervention strategies for the prevention and promotion of mental health.Objetivo: identificar la prevalencia, la gravedad y los factores asociados a la depresión entre los estudiantes universitarios del Distrito Federal. Método: estudio transversal realizado con 521 estudiantes universitarios, con edades comprendidas entre 18 y 60 años. Los síntomas depresivos se evaluaron mediante la escala del Patient Health Questionnaire-9 (PHQ-9). Se utilizó estadística descriptiva y la prueba de chi-cuadrado. Resultados: Entre los 521 individuos estudiados, predominó el sexo femenino. La prevalencia de síntomas depresivos fue de 521(96.6%) estudiantes universitarios, 31.3% con depresión leve, 23.4%, depresión mínima, 13.1% depresión moderadamente severa, 9.6% depresión severa y 9, 2% de depresión moderada. Los ingresos familiares y el semestre asistido son factores asociados para la gravedad de la depresión. Conclusión: la prevalencia de depresión en el entorno  universitario es común, siendo una proporción alta y preocupante. Es crucial rastrear la depresión, su gravedad y sus factores asociados, para estimular la reflexión sobre el tema y pensar en estrategias de intervención para la prevención y promoción de la salud mental

Surface modification of bamboo fibers using chitosan and functionalization with AuNPs

In this work, a new surface modification of the bamboo substrate with chitosan was studied, followed by subsequent treatment with gold nanoparticles (AuNP) by the exhaustion method, aiming at obtaining a technical textile with ultraviolet (UV) protection. The treatment with chitosan in the bamboo substrate induced an increase in the AuNP adsorption due to the electrostatic interactions between the chitosan amino groups and the citrate ion that surrounds the AuNP. The nanoparticles were obtained by the chemical reduction method, with some adaptations, using sodium citrate as a reducing agent/stabilizer and chlorouronic acid as precursor. The AuNP were characterized by transmission electron microscopy (TEM) and reflection, showing an average size of 35 nm. The presence of AuNP on the fiber surface was confirmed by SEM and XRD, with crystallographic peaks characteristic of gold. The UV protection factor was tested on the material, demonstrating excellent results.info:eu-repo/semantics/publishedVersio

Teoria e prática: as aulas remotas na pandemia

Este artigo relata a experiência de ministrar aulas remotas, durante o período da pandemia de covid-19, no Curso de Comunicação Social de uma faculdade particular em Manaus (AM), para mostrar o confronto entre a priorização da teoria ou da prática no âmbito do ensino superior, em um momento em que o mundo se viu obrigado a viver em isolamento social parcial ou total – o que nos leva, antes de tudo, a compreender a problemática entre teoria e prática antes da pandemia. A pesquisa tem como métodos e técnicas: a etnografia, a pesquisa de campo com observação participativa e entrevistas, com base em Morin, Bauman e outros. Os resultados apontam para que, apesar dos esforços para a continuidade do ensino teórico e prático, não existe ainda uma resposta definitiva para essa problemática, com ou sem a pandemia.This experience report explore the remote classes teaching implemented by a Social Communication program from a private university in Manaus, during the covid-19 pandemic, to show the confrontation between theory and practice within higher education, at a time when the world was forced to live in total or partial social isolation – which leads us, first of all, to understand the issue between theory and practice before the pandemic. Ethnography, field research with participatory observation and interviews, based on Morin, Bauman, among others, act as its theoretical framework. Results show that despite efforts to continue theoretical and practical teaching, there is still no definitive answer to this problematic exists, with or without the pandemic.

National Policy on Technical Assistance and Rural Extension and Social Work: the field to challenge

Discute a PNATER, tendo como enfoque a atuação do Assistente Social enquanto membro da equipe técnica. Fundamenta-se na perspectiva crítica, com base no materialismo histórico dialético e foi realizada através de pesquisa bibliográfica, documental e empírica. Está organizado em quatro sessões, que tratam sequencialmente sobre: a trajetória histórica das ações de assistência técnica e extensão rural; a PNATER na atualidade e os desafios de sua execução; a atenção à área social como tarefa premente; e a atuação do Serviço Social, enquanto técnico de ATER. Indica-se a necessidade de superação dos limites da política, dentre os quais está o enfoque tecnológico e desenvolvimentista; a necessária visibilidade do âmbito social na execução da mesma; e as possibilidades de atuação do Assistente Social como agente de ATER.Discusses the PNATER, focusing on the role of the social worker as a member of the technical staff. Based on the critical perspective on the basis of dialectical and historical materialism was conducted through bibliographic research, documentary and empirical. It is organized into four sections, which deal sequentially on: the historical trajectory of the actions of technical assistance and rural extension, the PNATER today and the challenges of its implementation; attention to the social job as urgent, and the role of Social Work while ATER technical. Indicates the necessity of overcoming the limits of the policy, among whom are the technological and developmentalist approach, the necessary visibility of the social context in the execution of the same, and the possibilities of acting of the social worker as agent of ATER