This work aimed to select potentially useful rhizobacteria for the control of Meloidogyne exigua, a widely disseminated root-knot nematode found in Brazilian coffee fields. Initially, crude metabolites produced in liquid medium by 69 isolated rhizobacteria strains (previously obtained from several plants collected in the south of Minas Gerais State, Brazil) were tested in vitro for lethality towards M. exigua second stage juveniles (J 2 ). Substances produced by strains of Bacillus cereus, B. megaterium, B. pumilus, B. thuringiensis, Enterobacter asburiae, E. cloacae and Paenibacillus macerans caused high mortality in J 2 . Subsequently, the ten most active crude metabolites were selected and assessed for nematicidal activity in a biotest with M. exiguainoculated coffee plants. Although strains of B. cereus, B. pumilus and P. macerans caused a significant reduction in the number of root galls and/ or nematode eggs per plant 90 days after treatment, the best results were obtained with the application of B. megaterium strain 54-06.
Esta pesquisa foi conduzida com o objetivo de verificar o melhor nível de torta de dendê na dieta de cordeiros por meio da avaliação da condição hepática. Foram utilizados 32 cordeiros Santa Inês não-castrados distribuídos em quatro dietas com 0,0; 6,5; 13,0 e 19,5% de torta de dendê na matéria seca (MS). A cada 15 dias, foram coletadas amostras de sangue dos animais, totalizando cinco coletas em todo o período experimental. Foram determinados os teores de triglicérides, colesterol, proteínas totais, albumina e globulina; as atividades das enzimas alanina aminotransferase (ALT), aspartatoaminotransferase (AST) e gama glutamiltransferase (GGT); e as concentrações séricas de bilirrubina total, direta e indireta. O aumento do percentual de torta de dendê na dieta não influenciou a concentração de triglicérides, cujo valor médio foi de 40,57 mg/dL, mas elevou as concentrações de colesterol. Também não ocasionou diferença no conteúdo de proteínas totais, mas teve efeito quadrático crescente nos níveis de albumina e ureia e efeito linear decrescente nos níveis de globulinas. Não foram observadas diferenças estatísticas nas atividades das enzimas alanina-aminotransferase, aspartato-aminotransferase e gama-glutamiltransferase, que foram de 6,40; 37,59 e 62,38 UI/L, respectivamente. Igualmente, não foi detectada influência sobre a bilirrubina total, direta e indireta, cujas médias foram de 0,50; 0,11; e 0,38 mg/dL, respectivamente. O uso de torta de dendê em níveis de até 19,5% da dieta não causa transtornos metabólicos hepáticos em cordeiros.
To contribute to the development of products to control Meloidogyne exigua, the bacteria Bacillus cereus and B. subtilis were cultivated in liquid medium to produce metabolites active against this plant-parasitic nematode. Fractionation of the crude dichloromethane extracts obtained from the cultures afforded uracil, 9H-purine and dihydrouracil. All compounds were active against M. exigua, the latter being the most efficient. This substance presented a LC 50 of 204 µg/mL against the nematode, while a LC 50 of 260 µg/mL was observed for the commercial nematicide carbofuran. A search for protein-ligand complexes in which the ligands were structurally similar to dihydrouracil resulted in the selection of phosphoribosyltransferases, the sequences of which were used in an in silico search in the genome of M. incognita for a similar sequence of amino acids. The resulting sequence was modelled and dihydrouracil and 9H-purine were inserted in the active site of this putative phosphoribosyltransferase resulting in protein-ligand complexes that underwent molecular dynamics simulations. Calculation of the binding free-energies of these complexes revealed that the dissociation constant of dihydrouracil and 9H-purine to this protein is around 8.3 x 10 -7 and 1.6 x 10 -6 M, respectively. Consequently, these substances and the putative phosphoribosyltransferase are promising for the development of new products to control M. exigua.
As nematodes cause great damage to Brazilian coffee production, effective methods to control these parasites are necessary. In a previous work Allium cepa L., Cajanus cajan (L.) Mill., Crotalaria juncea L., Ficus elastica Roxb., Ruta graveolens L., Stylosanthes guianensis Aubl., Leucaena leucocephala (Lam.) Dewit., Brachiaria decumbens Stapf., Catharanthus roseus G. Don, Tagetes minuta L., Ricinus communis L. and Coffea arabica L. produced active substances against Meloidogyne exigua Goeldi, a nematode widely disseminated through Brazilian coffee fields. Thus, aqueous extracts of such plants, collected in a different season from that of the previous work, as well as crude metabolites produced in liquid medium by Fusarium moniliforme Shelden and Cylindrocarpon magnusianum (Sacc.) Woll., were submitted to in vitro assays with M. exigua second-stage juveniles (J2). All plants and fungi produced active substances against J2. Therefore, their metabolites were applied to six-month-old coffee plants inoculated with M. exigua. After 90 days in a greenhouse, those samples obtained from A. cepa, L. leucocephala, R. graveolens and F. moniliforme inhibited the production of galls and eggs by M. exigua, demonstrating potential to control such parasite.Index terms: Fungi, Heteroderidae, nematicide, plant extract, Tylenchida. RESUMOOs nematóides acarretam grandes perdas aos produtores brasileiros de café, sendo necessário o desenvolvimento de métodos eficientes para o seu controle. Em trabalho anterior, Allium cepa L., Cajanus cajan (L.) Mill., Crotalaria juncea L., Ficus elastica Roxb., Ruta graveolens L., Stylosanthes guianensis Aubl., Leucaena leucocephala (Lam.) Dewit., Brachiaria decumbens Stapf., Catharanthus roseus G. Don, Tagetes minuta L., Ricinus communis L. e Coffea arabica L. produziram substâncias ativas contra o nematóide Meloidogyne exigua Goeldi, que é amplamente disseminado pelos cafezais brasileiros. Dando continuidade a esse trabalho, extratos aquosos das plantas mencionadas, coletadas em época diferente daquela mencionada no trabalho anterior, bem como metabólitos na forma bruta de Fusarium moniliforme Shelden e Cylindrocarpon magnusianum (Sacc.) Woll., produzidos em meio de cultura líquido, foram submetidos a testes in vitro com juvenis do segundo estádio (J2) de M. exigua. Todas as plantas e fungos produziram substâncias ativas contra J2. Portanto, seus metabólitos foram aplicados em mudas de café de seis meses de idade, inoculadas com M. exigua. Após 90 dias em casa de vegetação, verificou-se que os materiais oriundos de A. cepa, L. leucocephala, R. graveolens e F. moniliforme inibiram a produção de ovos e de galhas por M. exigua, demonstrando potencial para o controle de tal parasita.Termos para indexação: Extrato vegetal, fungos, Heteroderidae, nematicida, Tylenchida.
The rhizobacterium Paenibacillus macerans was grown in tryptic soy broth and after separating the cells by centrifugation the activity of fractions of the supernatant was tested against Meloidogyne exigua juveniles. From HPLC analyses and spectral data, the most active fractions were found to contain alanine, glutamic acid, glycine, histidine, threonine and valine, which were probably produced by bacterial hydrolysis of proteic nutrients. Amino acids from commercial sources were then assayed to confirm these results and to evaluate their potential for the control of nematodes. LC 50 of 26 and 283 μg ml −1 were shown for the nematicide aldicarb and L-cysteine respectively when tested on M. exigua juveniles. At a concentration 38.4 times>LC 50 , the amino acid diminished the nematode population on coffee plants to values statistically equal to those obtained with aldicarb at a concentration 19.2 times>LC 50 .
This study intends to present Bradford assay as an alternative to Lowry test to quantify hair damage during combing or brushing. The protocol involves collecting hair fragments that are chipped away from hair during these abrasive treatments and quantitatively measuring the amount of protein using an analytical procedure to detect low amounts of proteins. This protein determination method involves the binding of Coomassie Brilliant Blue G‐250 to hair protein (keratin). It is quite rapid and sensitive and less prone to interferences as the standard Lowry procedure. The latter is subject to interference from compounds such as lipids, cationic surfactants and EDTA, which are ingredients commonly used in hair care formulations and may lead to a false positive result. These drawbacks should be eliminated when using the so called Bradford method for hair protein quantitation. Our studies showed reproducible results for human hair protein and the developed color was stable for up to one hour. The data also show that virgin hair releases less protein than bleached hair. The amount detected for the former after combing ranges from 0.875 to 1.03 mg g–1 of hair and 4.85 to 5.35 mg g–1 of hair for the latter.
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