Expression and purification of active shikimate dehydrogenase from Plasmodium falciparum.

Plasmodium falciparum is known to cause severe malaria, current treatment consists in artemisinin-based combination therapy, but resistance can lead to treatment failure. Knowledge concerning P. falciparum essential proteins can be used for searching new antimalarials, among these a potential candidate is shikimate dehydrogenase (SDH), an enzyme part of the shikimate pathway which is responsible for producing endogenous aromatic amino acids. SDH from P. falciparum (PfSDH) is unexplored by the scientific community, therefore, this study aims to establish the first protocol for active PfSDH expression. Putative PfSDH nucleotide sequence was used to construct an optimized expression vector pET28a+PfSDH inserted in E. coli BL21(DE3). As a result, optimal expression conditions were acquired by varying IPTG and temperature through time. Western Blot analysis was applied to verify appropriate PfSDH expression, solubilization and purification started with lysis followed by two-steps IMAC purification. Enzyme activity was measured spectrophotometrically by NADPH oxidation, optimal PfSDH expression occur at 0.1 mM IPTG for 48 hours growing at 37 °C and shaking at 200 rpm, recombinant PfSDH obtained after purification was soluble, pure and its physiological catalysis was confirmed. Thus, this study describes the first protocol for heterologous expression of PfSDH in soluble and active form.

Application of the theory of planned behavior with agent-based modeling for sustainable management of vegetative filter strips.

This study proposes an innovative socio-hydrological modeling framework for the development of environmental policies that are tailored to farmers' attitudes and economic interests but also optimize environmental criteria. From a farmers' on-site survey, a behavior model is developed based on a modified Theory of Planned Behavior (TPB). The dynamics of the social and environmental system is implemented by coupling an agent-based model (ABM) with an agro-hydrological model for vegetative filter strips (VFS). A case study is conducted with farmers from the Larqui river basin, Chile to understand their standpoint on VFS to reduce soil loss in their agricultural fields and protect water bodies. Partial least square structural equation modeling is used to analyze the survey on farmers' aspiration and attitudes. It showed that the constructs added to TPB (behavioral morality, behavioral willingness, knowledge) had a significant effect on modeling the intention and behavior of farmers to have VFS. Based on the survey, the farmers were categorized into perceptive, proactive, bounded rational and interactive agents. An ABM was developed using the behavioral categorization, related decision rules, and utility functions of agricultural activities including the VFS implementation and management. The results of the ABM corroborate with the survey of the farmers. The survey supports the view that the decision on the width of VFS is not solely dependent on the utility generated and the reduction in soil losses but also on the behavior of farmers. This behavioral sociohydrological modeling framework is capable of supporting policy-makers in developing tailored environmental policies that might improve the acceptance of sustainable agricultural practices by farmers.

Exploring Novel Antimalarial Compounds Targeting Plasmodium falciparum Enoyl-ACP Reductase: Computational and Experimental Insights.

Malaria, caused by Plasmodium protozoa with Plasmodium falciparum as the most virulent species, continues to pose significant health challenges. Despite the availability of effective antimalarial drugs, the emergence of resistance has heightened the urgency for developing novel therapeutic compounds. In this study, we investigated the enoyl-ACP reductase enzyme of P. falciparum (PfENR) as a promising target for antimalarial drug discovery. Through a comprehensive analysis, we conducted a comparative evaluation of two lead compounds, LD1 (CID: 44405336, lead compounds 1) and LD2 (CID: 72703246, lead compounds 2), obtained from the PubChem/NCBI ligand database, to serve as reference molecules in the identification of potential derivatives using virtual screening assays. Among the newly identified candidates, Ligand 1 (LG1) and Ligand 2 (LG2) exhibited intriguing characteristics and underwent further investigation through docking and molecular dynamics simulations. Ligand 1 (LG1) demonstrated interactions similar to LD1, including hydrogen bonding with Asp218, while Ligand 2 (LG2) displayed superior binding energy comparable to LD1 and LD2, despite lacking hydrogen bonding interactions observed in the control compounds triclosan and its derivative 7-(4-chloro-2-hydroxyphenoxy)-4-methyl-2H-chromen-2-one (CHJ). Following computational validation using the MM/GBSA method to estimate binding free energy, commercially acquired LG1 and LG2 ligands were subjected to in vitro testing. Inhibition assays were performed to evaluate their potential as PfENR inhibitors alongside triclosan as a control compound. LG1 exhibited no inhibitory effects, while LG2 demonstrated inhibitory effects like triclosan. In conclusion, this study contributes valuable insights into developing novel antimalarial drugs by identifying LG2 as a potential ligand and employing a comprehensive approach integrating computational and experimental methodologies.

A rational in silico approach to identify inhibitors of Batroxrhagin from Bothrops atrox.

Bothrops atrox venom comprises several types of bioactive molecules, enzymatic and non-enzymatic, among those, Batroxrhagin is the most predominant SVMP P-III enzyme, which are responsible for induction of local and systemic hemorrhage and muscle fibers damage, impairing regeneration. Due to great difficulties in establishing an antibothropic drug, new strategies must be addressed to achieve a more effective and efficient treatment. There are no studies of specific catalytic inhibitors of Batroxrhagin. However, there are in vitro studies that have described similar metalloprotease inhibitors. The inhibitor batimastat was used as a leading compound for the search and selection of similar candidates. This molecule is widely cited as a metalloprotease inhibitor and as an antimetastatic. In addition to batimastat-like molecules, four other reported metalloprotease inhibitors were included to compose the study's positive control group. Hence, 580 molecules were tested. The three-dimensional structure of B. atrox Batroxrhagin was predicted based on homologous structures using Modeller 9.20. Molecular docking calculation was performed using Autodock 4.2 and molecular surfaces and interactions were analyzed using Biovia/Discovery Studio 2017. Among 576 molecules, 42 similar to batismast resulted in a better energy of interaction than all positive controls, including batimastat itself. The batimastat-like molecules with lowest energy and positive controls were subjected to molecular dynamics for 30 ns in Gromacs 2019.4. This batimastat-like molecule produced better stability among all the Batroxrhagin-ligand complexes analyzed. Overall, the proposed compounds present justifiable evidence for future in vitro tests aiming to inhibit Batroxrhagin. Communicated by Ramaswamy H. Sarma.

Ichthyofauna from tributaries of Urubu and Amazonas rivers, Amazonas State, Brazil / Ictiofauna de afluentes dos rios Urubu e Amazonas, Estado do Amazonas, Brasil

Abstract: The Amazonas River basin comprises the world's highest fish species diversity. Anthropogenic interferences in aquatic environments represent a pressure over the maintenance of ecological stability and biodiversity. We inventoried the ichthyofauna of 13 disturbed/modified tributaries of Urubu and Amazonas rivers in the region of the middle Amazon River, between June 2018 and March 2019. A total of 164 species were captured, represented by 11 orders, 37 families and 96 genera. Characiformes was the richest order, followed by Cichliformes and Siluriformes. The most representative families in number of species were Cichlidae, Serrasalmidae, and Characidae. Hemigrammus levis was the most abundant species, and Acarichthys heckelii the most common, registered in all sampled sites. In the present study, species with economic interest were collected, as well as many species recently described and one still waiting for formal description, identified provisionally as Moenkhausia aff. colletii. Therefore, the high fish diversity registered, even in disturbed environments in Middle Amazonas River, denotes the makeable ecological importance of this region for fishes resources and supports the necessity of evaluation of other aquatic environments in the region, as well as the potential impacts on composition, maintenance, and survival of ichthyofauna in environments directly affected by human activities.

Resumo: A bacia do rio Amazonas compreende a maior diversidade de espécies de peixes do mundo. Interferências antropogênicas em ambientes aquáticos representam uma pressão sobre a manutenção da estabilidade ecológica e da biodiversidade. Inventariamos a ictiofauna de 13 afluentes perturbados/modificados dos rios Urubu e Amazonas na região do médio do rio Amazonas, entre junho de 2018 e março de 2019. Foram capturadas 164 espécies no total, representadas por 11 ordens, 37 famílias e 96 gêneros. Characiformes foi a ordem mais rica, seguida por Cichliformes e Siluriformes. As famílias mais representativas em número de espécies foram Cichlidae, Serrasalmidae e Characidae. Hemigrammus levis foi a espécie mais abundante e Acarichthys heckelii a mais comum, registrada em todos os locais amostrados. No presente estudo foram coletadas espécies de interesse econômico, bem como muitas espécies recentemente descritas e uma ainda aguardando descrição formal, identificada provisoriamente como Moenkhausia aff. colletii. Portanto, a alta diversidade de peixes registrada, mesmo em ambientes perturbados no médio rio Amazonas, denota a importância ecológica marcante dessa região para os recursos pesqueiros e suporta a necessidade de avaliação de outros ambientes aquáticos da região, bem como os possíveis impactos na composição, manutenção e sobrevivência da ictiofauna em ambientes diretamente afetados pelas atividades humanas.

Ichthyofauna from floodplain lakes of Reserva de Desenvolvimento Sustentável Piagaçu-Purus (RDS-PP), lower rio Purus / Ictiofauna de lagos de várzea da Reserva de Desenvolvimento Sustentável Piagaçu-Purus (RDS-PP), baixo rio Purus

Abstract: The ichthyofauna of the rio Purus has been little investigated, especially in its lower portion, characterized by diverse aquatic environments, especially in flooded areas. We inventoried the ichthyofauna of floodplain lakes with different management efforts in Reserva de Desenvolvimento Sustentável Piagaçu-Purus (RDS-PP), which represent important resource for commercial fishing in North region, in the first illustrated inventory of the fish fauna from lower rio Purus. We surveyed 20 lakes, classified as open access (eight lakes) and protected (12 lakes) during 2009 low water levels. A total of 2,299 individuals were collected, represented by seven orders, 25 families and 74 species. Characiformes was the most representative order in number of species and families, followed by Siluriformes, Cichliformes, Gymnotiformes, Clupeiformes, and Osteoglossiformes. Most abundant and frequent species were Pygocentrus nattereri, Triportheus angulatus, Serrasalmus sp. "2n=58", Pterygoplichthys gibbiceps, and Osteoglossum bicirrhosum. Protected lakes presented higher species richness compared to open access lakes. Similarly, protected lakes possessed 26 species occurring exclusively, with emphasis on Colossoma macropomum, an important species for fisheries due to its commercial importance. We added 44 new records of fish species for the lower rio Purus. Our results indicate the potential efficiency of zoning systems of open access and protected lakes established by local population and ruled by RDS-PP for fisheries management. Therefore, we strongly suggest its maintenance for conservation of ichthyofauna of floodplain lakes of lower rio Purus.

Resumo: A ictiofauna do rio Purus tem sido pouco investigada, especialmente em seu curso inferior, caracterizada pela diversidade de ambientes aquáticos, especialmente em áreas de inundação. Inventariamos a ictiofauna dos lagos de várzea com diferentes tipos de manejo na Reserva de Desenvolvimento Sustentável Piagaçu-Purus (RDS-PP), que representa importante recurso para pesca commercial na região Norte, no primeiro inventário ilustrado da fauna de peixes do baixo rio Purus. Amostramos 20 lagos classificados como de uso (oito lagos) e proteção (12 lagos), durante o período de águas baixas de 2009. Foi coletado um total de 2.299 indivíduos representados por sete ordens, 25 famílias e 74 espécies. Characiformes foi a ordem mais representativa em número de espécies e famílias, seguida por Siluriformes, Cichliformes, Gymnotiformes, Clupeiformes e Osteoglossiformes. As espécies mais abundantes e frequentes foram Pygocentrus nattereri, Triportheus angulatus, Serrasalmus sp. "2n=58", Pterygoplichthys gibbiceps e Osteoglossum bicirrhosum. Lagos de proteção apresentaram maior riqueza de espécies comparados aos lagos de uso. Similarmente, lagos de proteção possuíam 26 espécies ocorrendo exclusivamente nesta categoria, com ênfase no Colossoma macropomum, uma espécie importante para pesca devido ao seu valor comercial. Adicionamos 44 novos registros de espécies de peixes para o baixo rio Purus. Nossos resultados indicam a potencial eficácia do sistema de zoneamento de lagos de uso e proteção para o manejo da pesca estabelecido pela população local e regulamentada pela RDS-PP. Portanto, sugerimos fortemente sua manutenção para conservação da ictiofauna dos lagos de várzea do baixo rio Purus.

Ichthyofauna of the Diamante stream, Caiuá Ecological Station (Diamante do Norte, Paraná State): monitoring its composition and structure - DOI: 10.4025/actascibiolsci.v31i2.3907 / Ictiofauna do ribeirão Diamante, Estação Ecológica do Caiuá (Diamante do Norte, Estado do Paraná): monitoramento de sua composição e estrutura - DOI: 10.4025/actascibiolsci.v31i2.3907

The aim of this study was to assess of composition and structure of ichthyofauna over two distinct periods: three and eleven years after the establishment of the protected area. The results of composition and structure of the ichthyofauna of the Diamante River, sampled quarterly from November 2005 to August 2006, were compared to results obtained by Abilhoa and Bastos (2005) in studies conducted between August 1997 and December 1998. The 2.4 to 16 cm-mesh gillnets were exposed for 24 hours and checked every 8 hours. In order to characterize the ichthyofauna, patterns of species richness, diversity, evenness and frequency of occurrence of species were analyzed. A total of 673 individuals, distributed among 36 species, 13 families and four orders were sampled. Significant changes were found in ichthyofauna composition, with a reduction in diversity and evenness as compared to the previous study. The high representativeness of alien species indicates instability in the studied area, through changes in diversity, species replacement, predominance of opportunistic species, and physical changes such as silting and degradation of the body of water.

O objetivo do presente trabalho foi investigar as assembleias de peixes do ribeirão Diamante (Estação Ecológica do Caiuá), visando avaliar sua composição e estrutura, ao longo de dois períodos distintos: três e 11 anos após sua criação. Para tanto, foram comparados os resultados obtidos nas amostragens realizadas trimestralmente no presente estudo, entre novembro de 2005 e agosto de 2006, com os resultados apresentados por Abilhoa e Bastos (2005) para o período de agosto de 1997 a dezembro de 1998. Neste estudo, os aparelhos de pesca foram constituídos de redes de espera simples com malhas de 2,4 a 16 cm (entre nós opostos), expostas por 24h, com revistas a cada 8h. Para a caracterização da ictiofauna, foram analisados padrões de riqueza específica, diversidade, equitabilidade e frequência de ocorrência das espécies. Foram capturados 673 indivíduos, distribuídos em 36 espécies, 13 famílias e quatro ordens. Verificou-se significativa alteração na composição da ictiofauna do ribeirão, com redução na diversidade e equitabilidade em relação ao trabalho anterior. Observou-se alta representatividade de espécies exóticas, o que indica instabilidade na área de estudo pelas alterações na diversidade, substituição de espécies, predomínio de oportunistas e alterações físicas como assoreamento e degradação do corpo de água.

Conocimientos sobre el SIDA y actitudes frente al enfermo en los alumnos del quinto año de secundaria de la Gran Unidad Escolar Mariano Melgar Arequipa 1996

El presente estudio es un trabajo descriptivo y transversal. Se aplicó un aencuesta sobre conocimientos y actitudes frente al SIDA en alumnos del quinto año de secundaria en el mes de mayo de 1996, con el objetivo de determinar el grado de conocimientos sobre el SIDA y las actitudes hacia el infectado por VIH-SIDA. La población encuestada fué de 299 alumnos de ambos sexos, cuya edad oscila de 15 a 18 años. El cuestionario de conocimientos constó de 20 items con alternativas de verdadero y falso, según corresponda, el juicio de valor final corregida (duplicada) fue: Bueno (20 a 14 puntos), regular (12 a 8 puntos) obteniéndose que el grado de conocimientos es ascentes de regular a bueno, con una media de 14,98 puntos, cal;ificativo que esta determinado en bueno. El cuestionario de actitudes constó de 12 items, calificado de acuerdo a la escala de Likert (65 puntos), con la calificación final de actitudes favorables mayor o igual a 40 puntos, y desfavorables menor a 40 puntos: Obteniendose que el 91,97 por ciento del total de alumnos tienen actitudes favorables, hacia el afectado por el VIH-SIDA. Se tiene que el 27.09 por ciento del total tuvo inicio de relaciones sexuales, de los cuales 61.73 por ciento no usaron condón constituyendose así ser una población con riesgo personal.

Conocimientos sobre el SIDA y actitudes frente al enfermo en los alumnos del quinto año de secundaria dela Gran Unidad Escolar Mariano Melgar Arequipa-1996

El presente estudio es un trabajo descriptivo y transversal. Se aplicó una encuesta sobre conocimientos y actitudes frente al SIDA en alumnos del quinto año de secundaria en el mes de mayo de 1996, con el objetivo de determinar el grado de conocimientos sobre el SIDA y las actitudes hacia el infectado por VIH-SIDA. La población encuestada fue de 299 alumnos de ambos sexos, cuya edad oscila de 15 a 18 años. El cuestionario de conocimientos constó de 20ítems con alternativas de verdadero y falso, según corresponda, el juicio de valor final corregida (duplicada) fue: bueno (20 a 14 puntos), regular (12 a 8 puntos) y malo (6 a 0 puntos), obteniéndose que el grado de conocimientos es ascendente de regular a bueno, con una media de 14,98 puntos, calificativo que esta determinado en bueno. El cuestionario de actitudes constó de 12 ítems, calificado de acuerdo a la escala de Likert (65 puntos), con la calificación final de actitudes favorables mayor o igual a 40 puntos y desfavorables menor a 40 puntos; obteniéndose que el 91,97 por ciento del total de los alumnos tienen actitudes favorables, hacia el infectado por el VIH-SIDA. Se tiene que el 27.09 por ciento del total tuvo inicio de relaciones sexuales, de los cuales 61.73 por ciento no usaron condón constituyendose asi ser una población con riesgo personal.