Agregando valores a las cadenas de valor

Este artículo presenta una matriz de factores a tomar en cuenta para priorizar las cadenas de valor agrícolas seleccionadas como foco de las iniciativas público-privadas para impulsar su desarrollo. Dichos factores dan especial importancia a temas de responsabilidad social empresarial. Se ilustra su uso con datos y una revisión de la literatura sobre Perú.

Hexachlorophene as a topically applied chemical for prophylaxis against Schistosoma mansoni infections in mice

Treatment of mouse tail skins with hexachlorophene (1.25% w/v) in absolute methanol or 70% isopropanol suppressed Schistosoma mansoni infections by more than 95% even when the application was performed up to three days prior to exposure to cercarial suspensions by tail immersion. Treatment with concentrations of 0.313% or higher one day prior to exposure provided at least 98% protection when the treated surface was not subjected to water washes of greater duration than 1/2 hour. Tail immersion application of 1.25% hexachlorophene one day prior to exposure still provided 87-92% protection after 3 hours water wash. Wipe application of 1.25% hexachlorophene three days prior to exposure still provided 93% protection following 3 hours water wash. High cercarial recoveries from exposure tubes at the end of exposure periods indicated high antipenetrant activity for hexachlorophene. Sufficient hexachlorophene leached from treated tail skins into the surrounding water to affect subsequently added cercariae so that they were no longer infective to untreated mice.

TRANFUSION-TRANSMITED VIRUS (TTV) IN BRAZIL. PRELIMINARY REPORT

TTV is a recently discovered DNA virus, isolated from a patient with post-transfusion hepatitis of unknown etiology by Japanese researchers. In the present study, we evaluated the presence of TTV among chronic liver diseases patients in São Paulo and Pará states, representing two geographically distinct Brazilian regions. TTV DNA was found in 21/105 (20%) and 9/20 (45%) cases from São Paulo and Pará States, respectively. DNA sequence data confirmed the presence of TTV genotypes 1a and 2a, as well as other genotypes not yet described. In conclusion, TTV is present in chronic liver diseases cases from Southeast and North Brazil. However, further studies involving healthy populations are necessary before establishing any causal relationship among TTV and human hepatitis.

Transtorno de oposição e desafio e transtorno de conduta: os desfechos no TDAH em adultos

Os autores examinam a influência dos transtornos de oposição e desafio (TOD), de conduta (TC) e de personalidade anti-social (TPAS) ao longo da vida do indivíduo com TDAH. Os principais achados mostram que o TDAH é modulado por essas comorbidades e que seu prognóstico é modificado dependendo da presença ou não desses transtornos. O transtorno de oposição e desafio intensificaria as características de impulsividade e isolacionismo do TDAH, porém não acarretaria em um aumento na incidência de TPAS na vida adulta. Já o TC associado ao TDAH implica um aumento significativo na impulsividade e agressividade, estando associado significativamente a TPAS e um pior prognóstico. A diferenciação entre os diferentes transtornos e seu correto diagnóstico é essencial para o tratamento adequado do TDAH. Futuros estudos precisam determinar se o tratamento do TDAH produziria uma mudança significativa no prognóstico desse grupo de pacientes.

Genetic Variation among Natural and Laboratory Colony Populations of Lutzomyia longipalpis (Lutz & Neiva, 1912)(Diptera:Psychodidae) from Colombia

Genetic diversity among three field populations of Lutzomyia longipalpis in Colombia was studied using isozyme analysis. Study sites were as much as 598 km apart and included populations separated by the eastern Cordillera of the Andes. Genetic variability among populations, estimated by heterozygosity, was within values typical for insects in general (8.1%). Heterozygosity for field populations were compared with a laboratory colony from Colombia (Melgar colony) and were only slightly lower. These results suggest that establishment and long term maintenance of the Melgar colony has had little effect on the level of isozyme variability it carries. Genetic divergences between populations was evaluated using estimates of genetic distance. Genetic divergence among the three field populations was low (D=0.021), suggesting they represent local populations within a single species. Genetic distance between field populations and the Melgar colony was also low (D=0.016), suggesting that this colony population does not depart significantly from natural populations. Finally, comparisons were made between Colombian populations and colonies from Brazil and Costa Rica. Genetic distance values were high between Colombian and both Brazil and Costa Rica colony populations (D=0.199 and 0.098 respectively) providing additional support for our earlier report that populations from the three countries represent distinct species

Resolution of an Infection with Leishmania braziliensis Confers Complete Protection to a Subsequent Challenge with Leishmania major in BALB/c Mice

Both Leishmania major and L. braziliensis induce cutaneous leishmaniasis in BALB/c mice. Whereas BALB/c mice die of infection with L. major, they cure an infection with L. braziliensis. We report here that after curing an infection with L. braziliensis, BALB/c mice are resistant to challenge with L. major. When challenged with L. major, L. braziliensis pre-treated BALB/c mice mounted a delayed-type hypersensitivity response to L. major and produced high amounts of interferon-g (IFN-g ) but low amounts of interleukin-4. The IFN-g produced by the L. braziliensis pre-infected mice was involved in the protection seen against L. major challenge since treating the mice with a neutralizing anti-IFN-g abrogated the protection. This suggests that cross-reactive antigen epitopes exist between L. braziliensis and L. major and that pre-infection with L. braziliensis primes BALB/c mice to epitopes on L. major that can elicit a protective Th1 response to the parasite.

Colony polymerase chain reaction of stably transfected Trypanosoma cruzi grown on solid medium

Tools for the genetic manipulation of Trypanosoma cruzi are largely unavailable, although several vectors for transfection of epimastigotes and expression of foreign or recombinant genes have been developed. We have previously constructed several plasmid vectors in which recombinant genes are expressed in T. cruzi using the rRNA promoter. In this report, we demonstrate that one of these vectors can simultaneously mediate expression of neomycin phosphotransferase and green fluorescent protein when used to stably transfect cultured epimastigotes. These stably transfected epimastigotes can be selected and cloned as unique colonies on solid medium. We describe a simple colony PCR approach to the screening of these T. cruzi colonies for relevant genes. Thus, the methodologies outlined herein provide important new tools for the genetic dissection of this important parasite.

Mechanisms for suppressing NADPH oxidase in the vascular wall

Oxidative stress underlies many forms of vascular disease as well as tissue injury following ischemia and reperfusion. The major source of oxidative stress in the artery wall is an NADPH oxidase. This enzyme complex as expressed in vascular cells differs from that in phagocytic leucocytes both in biochemical structure and functions. The crucial flavin-containing catalytic subunits, Nox1 and Nox4, are not found in leucocytes, but are highly expressed in vascular cells and upregulated with vascular remodeling, such as that found in hypertension and atherosclerosis. The difference in catalytic subunits offers the opportunity to develop "vascular specific" NADPH oxidase inhibitors that do not compromise the essential physiological signaling and phagocytic functions carried out by reactive oxygen and nitrogen species. Nitric oxide and targeted inhibitors of NADPH oxidase that block the source of oxidative stress in the vasculature are more likely to prevent the deterioration of vascular function that leads to stroke and heart attack, than are conventional antioxidants. The roles of Nox isoforms in other inflammatory conditions are yet to be explored.

Anopheles darlingi polytene chromosomes: revised maps including newly described inversions and evidence for population structure in Manaus

Salivary gland polytene chromosomes of 4th instar Anopheles darlingi Root were examined from multiple locations in the Brazilian Amazon. Minor modifications were made to existing polytene photomaps. These included changes to the breakpoint positions of several previously described paracentric inversions and descriptions of four new paracentric inversions, two on the right arm of chromosome 3 and two on the left arm of chromosome 3 that were found in multiple locations. A total of 18 inversions on the X (n = 1) chromosome, chromosome 2 (n = 7) and 3 (n = 11) were scored for 83 individuals from Manaus, Macapá and Porto Velho municipalities. The frequency of 2Ra inversion karyotypes in Manaus shows significant deficiency of heterozygotes (p < 0.0009). No significant linkage disequilibrium was found between inversions on chromosome 2 and 3. We hypothesize that at least two sympatric subpopulations exist within the An. darlingi population at Manaus based on inversion frequencies.

Decomposição e liberação de nutrientes acumulados em leguminosas herbáceas perenes consorciadas com bananeira

A avaliação da decomposição dos resíduos vegetais adicionados ao solo pelas plantas de cobertura permite melhor compreensão do fornecimento de nutrientes para as culturas de interesse comercial. O presente estudo foi realizado no campo com o objetivo de avaliar a decomposição e a liberação de nutrientes pela parte aérea de leguminosas herbáceas perenes. Os tratamentos consistiram de diferentes plantas de cobertura do solo consorciadas com bananeira: amendoim forrageiro (Arachis pintoi Krapov. & W.C. Gregory), cudzu tropical (Pueraria phaseoloides (Roxb.) Benth.), siratro (Macroptilium atropurpureum (Sessé & Moc. ex DC.) Urb.) e vegetação espontânea com predomínio de capim-colonião (Panicum maximum Jacq.). Essas espécies foram cortadas na estação seca (abril de 1997) e na estação chuvosa (janeiro de 1998). Após cada corte, amostras da parte aérea foram acondicionadas em sacos de tela ("litterbags") distribuídos na superfície das parcelas. A decomposição da matéria seca e a liberação de nutrientes foram monitoradas por meio de coletas dos resíduos contidos nos sacos de tela, realizadas 5, 10, 15, 30, 60, 90, 120 e 150 dias após o corte das plantas de cobertura. Os resíduos de amendoim forrageiro apresentaram maior velocidade de decomposição, enquanto a vegetação espontânea mostrou um comportamento mais lento. As constantes de decomposição diminuíram e os tempos de meia-vida aumentaram na estação seca. Houve rápida liberação de N, Ca e Mg pelas leguminosas, enquanto a vegetação espontânea apresentou o mesmo comportamento para P. Com relação à composição química dos resíduos, os teores de celulose e hemicelulose mostraram-se correlacionados com as perdas de matéria seca. As liberações de N foram correlacionadas com os teores de C e hemicelulose. Os dados indicam o potencial das leguminosas herbáceas perenes na liberação de nutrientes, com destaque para cudzu tropical e siratro.

Potencial de quatro espécies herbáceas forrageiras para fitorremediação de solo contaminado por arsênio

A fitorremediação de solos e substratos contaminados por elementos tóxicos tem despertado crescente interesse entre pesquisadores e técnicos. Particularmente em relação ao As, o obstáculo ao emprego desta técnica é o pequeno número de espécies identificadas capazes de acumular este elemento. O objetivo deste trabalho foi avaliar o potencial de plantas de estilosante (Stylosanthes humilis HBK), amendoim (Arachis pintoi Krapov. & Gregory), aveia (Avena strigosa Schreb) e azevém (Lolium multiflorum Lam.) como espécies fitorremediadoras de áreas contaminadas por As. Amostras de Latossolo Vermelho-Amarelo foram incubadas por 15 dias com diferentes doses de As: 0; 50; 100; e 200 mg dm-3. Em seguida, realizaram-se a semeadura das quatro espécies e as respectivas adubações. Aos 65 dias após a semeadura, as plantas foram avaliadas quanto à altura, à matéria seca da parte aérea e raízes. Determinaram-se os teores de As nas folhas jovens, intermediárias e basais, no caule e nas raízes, bem como o conteúdo e o índice de translocação (IT) de As. Por meio de análises de regressão, foram estimados os teores críticos (TC) de As disponíveis no solo, que proporcionaram redução de 50 % da matéria seca. As espécies estudadas apresentaram comportamento diferenciado quanto à tolerância ao As, com destaque para azevém, amendoim e estilosante, que não apresentaram lesões foliares decorrentes de fitotoxidez por esse elemento. Os TC para as plantas de aveia e azevém foram significativamente superiores aos observados para as demais espécies, caracterizando-as como espécies tolerantes ao As. As plantas de amendoim e estilosante apresentaram maior capacidade de absorção e maior IT de As para a parte aérea. As plantas de amendoim apresentaram maiores teores nas folhas basais e raízes, mostrando potencial para serem utilizadas em programas de fitorremediação. As plantas de azevém, amendoim e estilosante podem ser utilizadas na fitoestabilização e, ou, na revegetação de áreas contaminadas por As, uma vez que apresentaram tolerância a esse elemento. Por se tratar de espécies forrageiras, quando utilizadas para esses fins, cuidados especiais são necessários, como o isolamento da área, para evitar a entrada do elemento na cadeia trófica.

An improved method for measuring soil microbial activity by gas phase flow injection analysis

The rate of carbon dioxide production is commonly used as a measure of microbial activity in the soil. The traditional method of CO2 determination involves trapping CO2 in an alkali solution and then determining CO2 concentration indirectly by titration of the remaining alkali in the solution. This method is still commonly employed in laboratories throughout the world due to its relative simplicity and the fact that it does not require expensive, specific equipment. However, there are several drawbacks: the method is time-consuming, requires large amounts of chemicals and the consistency of results depends on the operator's skills. With this in mind, an improved method was developed to analyze CO2 captured in alkali traps, which is cheap and relatively simple, with a substantially shorter sample handling time and reproducibility equivalent to the traditional titration method. A comparison of the concentration values determined by gas phase flow injection analysis (GPFIA) and titration showed no significant difference (p > 0.05), but GPFIA has the advantage that only a tenth of the sample volume of the titration method is required. The GPFIA system does not require the purchase of new, costly equipment but the device was constructed from items commonly found in laboratories, with suggestions for alternative configurations for other detection units. Furthermore, GPFIA for CO2 analysis can be equally applied to samples obtained from either the headspace of microcosms or from a sampling chamber that allows CO2 to be released from alkali trapping solutions. The optimised GPFIA method was applied to analyse CO2 released from degrading hydrocarbons from a site contaminated by diesel spillage.

Produção de híbridos de amendoim forrageiro por meio de hibridação artificial

O objetivo deste trabalho foi a obtenção de híbridos de amendoim forrageiro por meio da hibridação artificial. O experimento foi realizado na Embrapa-Centro Nacional de Pesquisa de Recursos Genéticos e Biotecnologia, durante a época de florescimento dos acessos de Arachis pintoi Krap. & W. C. Gregory e de A. repens Handro. Cerca de 700 polinizações produziram 27 segmentos de frutos, com taxas de fecundação que variaram entre 1,1 e 12,9%, considerando-se todas as combinações híbridas. Os híbridos intra-específicos de A. pintoi produziram sementes F2, e os interespecíficos não produziram semente. A técnica de hibridação utilizada nas espécies forrageiras necessitou de ajustes, devido a diferenças observadas em relação ao amendoim cultivado, entre elas o hábito de crescimento.

Feijão-vagem semeado sobre cobertura viva perene de gramínea e leguminosa e em solo mobilizado, com adubação orgânica

O objetivo deste trabalho foi avaliar o desempenho agronômico do feijão-vagem, cv. Alessa, cultivado sobre cobertura viva perene de grama-batatais (Paspalum notatum Flüggé) e de amendoim forrageiro (Arachis pintoi Krapov & Gregory), e em solo convencionalmente preparado, como controle. Diferentes doses de cama de aviário (0, 7, 14 e 28 t ha-1) foram fornecidas, parceladamente, em um Planossolo, em Seropédica, RJ, de agosto a outubro de 2002. O delineamento adotado foi o de blocos ao acaso, dispostos em parcelas subdivididas, com quatro repetições, utilizando-se modelo quadrático para análise dos resultados. A produtividade de vagens foi semelhante nos três sistemas de cultivo sem efeito competitivo das espécies de cobertura viva, sobre as quais foi realizada a semeadura direta da cultura, com enxada. A produtividade máxima estimada pelo modelo de regressão foi 20,3 t ha-1 de vagens. Esse valor foi obtido com a dose de 26 t ha-1 de cama de aviário, aplicada de forma parcelada. A semeadura direta de feijão-vagem sobre cobertura viva perene de grama-batatais e de amendoim forrageiro é viável, com resultados preliminares positivos.

Predicting chick body mass by artificial intelligence-based models

The objective of this work was to develop, validate, and compare 190 artificial intelligence-based models for predicting the body mass of chicks from 2 to 21 days of age subjected to different duration and intensities of thermal challenge. The experiment was conducted inside four climate-controlled wind tunnels using 210 chicks. A database containing 840 datasets (from 2 to 21-day-old chicks) - with the variables dry-bulb air temperature, duration of thermal stress (days), chick age (days), and the daily body mass of chicks - was used for network training, validation, and tests of models based on artificial neural networks (ANNs) and neuro-fuzzy networks (NFNs). The ANNs were most accurate in predicting the body mass of chicks from 2 to 21 days of age after they were subjected to the input variables, and they showed an R² of 0.9993 and a standard error of 4.62 g. The ANNs enable the simulation of different scenarios, which can assist in managerial decision-making, and they can be embedded in the heating control systems.