Angiotensin II-derived constrained peptides with antiplasmodial activity and suppressed vasoconstriction

Angiotensin II (Ang II) is a natural mammalian hormone that has been described to exhibit antiplasmodial activity therefore constituting a promising alternative for the treatment of malaria. Despite its promise, the development of Ang II as an antimalarial is limited by its potent induction of vasoconstriction and its rapid degradation within minutes. Here, we used peptide design to perform targeted chemical modifications to Ang II to generate conformationally restricted (disulfide-crosslinked) peptide derivatives with suppressed vasoconstrictor activity and increased stability. Designed constrained peptides were synthesized chemically and then tested for antiplasmodial activity. Two lead constrained peptides were identified (i.e., peptides 1 and 2), each composed of 10 amino acid residues. These peptides exhibited very promising activity in both our Plasmodium gallinaceum ( > 80%) and Plasmodium falciparum ( > 40%) models, an activity that was equivalent to that of Ang II, and led to complete suppression of vasoconstriction. In addition, peptide 5 exhibited selective activity towards the pre-erythrocytic stage (98% of activity against P. gallinaceum), thus suggesting that it may be possible to design peptides that target specific stages of the malaria life cycle. The Ang II derived stable scaffolds presented here may provide the basis for development of a new generation of peptide-based drugs for the treatment of malaria

Metabolismo e importância da arginina na nutrição de suínos

 The swine nutrition in recent years has been the focus of several experimental studies, especially in relation to protein and amino acid nutrition. In this context, arginine is one of the amino acid in increasing research, which metabolism is dynamic, participating in several metabolic pathways and generating numerous compounds. The arginine synthesis occurs primarily in the intestinal-renal axis, where lining cells from the small intestine produce citrulline and proximal tubule cells from kidney extract citrulline from the bloodstream, converting it into arginine, returning it to circulation. Arginine is chemically named 2-Amino-5-Guanidopentanoic Acid, and it is a conditionally nonessential amino acid for pigs, considering that is required primarily from 3 to 21 days age when the animal organism is capable of synthesizing about 60% of its requirements. Thus, arginine supplementation in diets for pregnant and lactating sows has been a tool to increase the performance of nursing piglets. However, there are evidences that high levels of arginine in the diet can cause an antagonism to the lysine, which is the first limiting amino acid for pigs, and it could adversely affect animal performance. Thus, this literature review aims to elucidate the arginine metabolism in swines, evidencing the importance of this amino acid in the nutrition of these animals.  A nutrição de suínos, nos últimos anos, tem sido foco de inúmeros trabalhos experimentais, principalmente em relação à nutrição protéica e aminoacídica.  Nesse contexto, um dos aminoácidos em crescente pesquisa é a arginina, cujo metabolismo é dinâmico, participando de diversas rotas metabólicas e gerando inúmeros compostos. A síntese da arginina ocorre principalmente no eixo intestino-renal, sendo que células do epitélio do intestino delgado produzem citrulina e células dos túbulos proximais, nos rins, extraem a citrulina da circulação sanguínea, convertendo-na em arginina, devolvendo-a para a circulação. A arginina, quimicamente denominada Ácido 2-amino-5-guanidopentanóico, é considerada um aminoácido condicionalmente não-essencial para suínos, haja vista que é primordialmente necessária dos 3 aos 21 dias de idade, momento em que o organismo animal é capaz de sintetizar cerca de 60% de suas exigências. Sendo assim, a suplementação de arginina em dietas para porcas gestantes e lactantes tem sido uma ferramenta para elevar o desempenho de leitões lactantes. Entretanto, existem evidências de que níveis elevados de arginina na dieta podem provocar um antagonismo com a lisina, que consiste no primeiro aminoácido limitante para suínos, o que poderia prejudicar o desempenho dos animais. Desse modo, esta revisão literária objetiva elucidar o metabolismo da arginina em suínos, evidenciando a importância desse aminoácido na nutrição desses animais. &nbsp

Cultura de embrião e indução de brotos in vitro para micropropagação do pinhão‑manso

O objetivo deste trabalho foi otimizar o cultivo e desenvolvimento de embriões, bem como avaliar a indução da micropropagação do pinhão‑manso (Jatropha curcas) in vitro. Na primeira etapa, foi avaliada a influência da sacarose (concentrações 0, 15, 30 e 60 g L-1) no desenvolvimento de embriões em meio basal MS. Das plântulas geradas no cultivo de embriões, foram excisadas microestacas e colocadas em meio MS suplementado com os reguladores vegetais 6‑benziladenina (BA), 6‑benzilaminopurina (BAP), cinetina (6‑furfuriladenina) (KIN) e ácido 4‑(3‑indolil) butírico (AIB), nas concentrações 0,5, 1,0, 2,0 e 3,0 mg L-1. Os resultados evidenciaram que a faixa de 15 a 30 g L-1 de suplementação exógena da sacarose promove o melhor alongamento da parte aérea das plantas; a rizogênese, contudo, é mais vigorosa na faixa de 30 a 60 g L-1, em que ocorre aumento significativo do número de raízes. Na fase de micropropagação, o BAP à concentração de 2,0 mg L-1 induz maior número de brotações, enquanto a KIN (1,0 e 2,0 mg L-1) promove maior número de folhas. Ocorre calogênese na base das brotações, mais significativa na suplementação com 2,0 mg L-1 de 6‑BAP. A melhor concentração de sacarose, quanto ao vigor vegetal e rapidez na obtenção de explantes, é de 30 g L-1. Na micropropagação, os melhores resultados da organogênese direta de brotações ocorrem à concentração de 2,0 mg L-1 de BAP.The objective of this work was to optimize the cultivation and embryo development, as well as to evaluate in vitro micropropagation induction of physic nut (Jatropha curcas). In the initial stage, the influence of sucrose (concentrations of 0, 15, 30 and 60 g L-1) on the development of embryos in basal MS medium was evaluated. From the seedlings generated in the embryo culture, microcuttings were excised and inoculated on MS medium supplemented with the plant regulators 6‑benzyladenine (BA), 6‑benzylaminopurine (BAP), kinetin (6‑furfuryladenine) (KIN) and 4‑(3‑indolyl) butyric acid (IBA), in the concentrations of 0.5, 1.0, 2.0 and 3.0 mg L-1. The results showed that the range of 15 to 30 g L-1 of exogenous supplementation with sucrose promotes the best shoot elongation of plants; however, rhizogenesis is more vigorous in the range from 30 to 60 g L-1, in which a significant increase of the number of roots occurs. In the micropropagation phase, BAP at 2.0 mg L-1 concentration induces a higher number of shoots, while KIN (1.0 and 2.0 mg L-1) promotes a higher number of leaves. Callogenesis occurs on the shoot base, being more significant when supplemented with 2.0 mg L-1 of 6‑BAP. The best sucrose concentration, for plant vigor and speed in obtaining explants, is 30 g L-1. In micropropagation, the best results for direct shoot organogenesis occur at 2.0 mg L-1 BAP concentration

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network

Science has a critical role to play in guiding more sustainable development trajectories. Here, we present the Sustainable Amazon Network (Rede Amazonia Sustentavel, RAS): a multidisciplinary research initiative involving more than 30 partner organizations working to assess both social and ecological dimensions of land-use sustainability in eastern Brazilian Amazonia. The research approach adopted by RAS offers three advantages for addressing land-use sustainability problems: (i) the collection of synchronized and co-located ecological and socioeconomic data across broad gradients of past and present human use; (ii) a nested sampling design to aid comparison of ecological and socioeconomic conditions associated with different land uses across local, landscape and regional scales; and (iii) a strong engagement with a wide variety of actors and non-research institutions. Here, we elaborate on these key features, and identify the ways in which RAS can help in highlighting those problems in most urgent need of attention, and in guiding improvements in land-use sustainability in Amazonia and elsewhere in the tropics. We also discuss some of the practical lessons, limitations and realities faced during the development of the RAS initiative so far.Keywords: Social–ecological systems, Tropical forests, Land use, Interdisciplinary research, Sustainability, Trade-off