Four plant defensins from an indigenous South African Brassicaceae species display divergent activities against two test pathogens despite high sequence similarity in the encoding genes

<p>Abstract</p> <p>Background</p> <p>Plant defensins are an important component of the innate defence system of plants where they form protective antimicrobial barriers between tissue types of plant organs as well as around seeds. These peptides also have other activities that are important for agricultural applications as well as the medical sector. Amongst the numerous plant peptides isolated from a variety of plant species, a significant number of promising defensins have been isolated from Brassicaceae species. Here we report on the isolation and characterization of four defensins from <it>Heliophila coronopifolia</it>, a native South African Brassicaceae species.</p> <p>Results</p> <p>Four defensin genes (<it>Hc-AFP1</it>-<it>4) </it>were isolated with a homology based PCR strategy. Analysis of the deduced amino acid sequences showed that the peptides were 72% similar and grouped closest to defensins isolated from other Brassicaceae species. The Hc-AFP1 and 3 peptides shared high homology (94%) and formed a unique grouping in the Brassicaceae defensins, whereas Hc-AFP2 and 4 formed a second homology grouping with defensins from <it>Arabidopsis </it>and <it>Raphanus</it>. Homology modelling showed that the few amino acids that differed between the four peptides had an effect on the surface properties of the defensins, specifically in the alpha-helix and the loop connecting the second and third beta-strands. These areas are implicated in determining differential activities of defensins. Comparing the activities after recombinant production of the peptides, Hc-AFP2 and 4 had IC₅₀values of 5-20 μg ml^-1against two test pathogens, whereas Hc-AFP1 and 3 were less active. The activity against <it>Botrytis cinerea </it>was associated with membrane permeabilization, hyper-branching, biomass reduction and even lytic activity. In contrast, only Hc-AFP2 and 4 caused membrane permeabilization and severe hyper-branching against the wilting pathogen <it>Fusarium solani</it>, while Hc-AFP1 and 3 had a mild morphogenetic effect on the fungus, without any indication of membrane activity. The peptides have a tissue-specific expression pattern since differential gene expression was observed in the native host. <it>Hc-AFP1 </it>and <it>3 </it>expressed in mature leaves, stems and flowers, whereas <it>Hc-AFP2 </it>and <it>4 </it>exclusively expressed in seedpods and seeds.</p> <p>Conclusions</p> <p>Two novel Brassicaceae defensin sequences were isolated amongst a group of four defensin encoding genes from the indigenous South African plant <it>H. coronopifolia</it>. All four peptides were active against two test pathogens, but displayed differential activities and modes of action. The expression patterns of the peptide encoding genes suggest a role in protecting either vegetative or reproductive structures in the native host against pathogen attack, or roles in unknown developmental and physiological processes in these tissues, as was shown with other defensins.</p

Approaches in biotechnological applications of natural polymers

Natural polymers, such as gums and mucilage, are biocompatible, cheap, easily available and non-toxic materials of native origin. These polymers are increasingly preferred over synthetic materials for industrial applications due to their intrinsic properties, as well as they are considered alternative sources of raw materials since they present characteristics of sustainability, biodegradability and biosafety. As definition, gums and mucilages are polysaccharides or complex carbohydrates consisting of one or more monosaccharides or their derivatives linked in bewildering variety of linkages and structures. Natural gums are considered polysaccharides naturally occurring in varieties of plant seeds and exudates, tree or shrub exudates, seaweed extracts, fungi, bacteria, and animal sources. Water-soluble gums, also known as hydrocolloids, are considered exudates and are pathological products; therefore, they do not form a part of cell wall. On the other hand, mucilages are part of cell and physiological products. It is important to highlight that gums represent the largest amounts of polymer materials derived from plants. Gums have enormously large and broad applications in both food and non-food industries, being commonly used as thickening, binding, emulsifying, suspending, stabilizing agents and matrices for drug release in pharmaceutical and cosmetic industries. In the food industry, their gelling properties and the ability to mold edible films and coatings are extensively studied. The use of gums depends on the intrinsic properties that they provide, often at costs below those of synthetic polymers. For upgrading the value of gums, they are being processed into various forms, including the most recent nanomaterials, for various biotechnological applications. Thus, the main natural polymers including galactomannans, cellulose, chitin, agar, carrageenan, alginate, cashew gum, pectin and starch, in addition to the current researches about them are reviewed in this article.. }To the Conselho Nacional de Desenvolvimento Cientfíico e Tecnológico (CNPq) for fellowships (LCBBC and MGCC) and the Coordenação de Aperfeiçoamento de Pessoal de Nvíel Superior (CAPES) (PBSA). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and COMPETE 2020 (POCI-01-0145-FEDER-006684) (JAT)

Treinamento muscular inspiratório em crianças com leucemia aguda: resultados preliminares Inspiratory muscle training in patients with acute leukemia: preliminary results

OBJETIVO: Avaliar o efeito do treinamento muscular inspiratório em crianças com leucemia aguda. MÉTODOS: Trata-se de um estudo quase experimental com grupo controle. Quatorze pacientes com diagnóstico de leucemia aguda e idade entre cinco e 14 anos foram submetidos à avaliação da mobilidade torácica e da força muscular respiratória e divididos em dois grupos (A e B). Os pacientes do grupo A realizaram treinamento muscular inspiratório domiciliar por 15 minutos, duas vezes por dia, durante dez semanas, através do aparelho Threshold®, com carga de 30% da pressão inspiratória máxima, reajustada após reavaliações semanais. O grupo B (controle) realizou uma avaliação das pressões respiratórias máximas inicialmente e após dez semanas. Os dados foram analisados com o SPSS 15.0. Aplicou-se o teste t para analisar as diferenças entre as pressões inspiratória máxima e expiratória máxima entre os dois grupos e o teste de correlação de Pearson para analisar associações das medidas de pressão inspiratória e pressão expiratória com as diferentes cargas utilizadas. RESULTADOS: Constatou-se ganho significativo de 35% nas pressões inspiratória máxima e expiratória máxima no grupo A ao término do treinamento. Houve correlação positiva entre os níveis de carga utilizada e a pressão inspiratória máxima (p<0,0001) e a pressão expiratória máxima (p=0,0001). CONCLUSÕES: O treinamento muscular inspiratório pode ser eficaz no ganho de força muscular em crianças em tratamento de leucemia aguda.<br>OBJECTIVE: To evaluate the effect of inspiratory muscle training in children with acute leukemia. METHODS: This is a quasi-experimental study with a control group. Fourteen patients with 5-14 years old and a diagnosis of acute leukemia were evaluated regarding their thoracic mobility and respiratory muscle strength. They were divided in two groups (A and B). Group A received domiciliary inspiratory muscle training during 15 minutes, twice a day, for ten weeks, with a Threshold® device using a load of 30% of the maximal inspiratory pressure, readjusted after weekly evaluations. Group B patients were tested regarding their maximum respiratory pressures in their first evaluation and after ten weeks. Student t-test was used to evaluate maximum inspiratory and expiratory pressures between groups Pearson's correlation test examined the association of inspiratory and expiratory pressures with the different loads, using SPSS 15.0 software. RESULTS: A significant improvement of 35% was observed in the maximum inspiratory and expiratory pressures in group A at the end of the training. There was a strong positive correlation between the used load levels and maximal inspiratory (p<0.0001) and expiratory (p=0.0001) pressures. CONCLUSIONS: Inspiratory muscle training can be effective for improving inspiratory muscle strength in children beeing treated for acute leukemia