Universidade Estadual de Londrina

About: Universidade Estadual de Londrina is a education organization based out in Londrina, Brazil. It is known for research contribution in the topics: Population & Context (language use). The organization has 13052 authors who have published 19291 publications receiving 212123 citations.

Mycorrhiza and soil bacteria influence extractable iron and manganese in soil and uptake by soybean

Abstract: Excess manganese (Mn) in soil is toxic to crops, but in some situations arbuscular mycorrhizal fungi (AMF) alleviate the toxic effects of Mn. Besides the increased phosphorus (P) uptake, mycorrhiza may affect the balance between Mn-reducing and Mn-oxidizing microorganisms in the mycorrhizosphere and affect the level of extractable Mn in soil. The aim of this work was to compare mycorrhizal and non-mycorrhizal plants that received extra P in relation to alleviation of Mn toxicity and the balance between Mn-oxidizing and Mn-reducing bacteria in the mycorrhizosphere. A clayey soil containing 508 mg kg−1 of extractable Mn was fertilized with 30 mg kg−1 (P1) or 45 mg kg−1 (P2) of soluble P. Soybean (Glycine max L. Merrill, cv. IAC 8-2) plants at P1 level were non-inoculated (CP1) or inoculated with either Glomus etunicatum (GeP1) or G. macrocarpum (GmP1), while plants at P2 level were left non-inoculated (CP2). Plants were grown in a greenhouse and harvested after 80 days. In the mycorrhizosphere of the GmP1 and GeP1 plants a shift from Mn-oxidizing to Mn-reducing bacteria coincided with higher soil extractability of Mn and Fe. However, the occurrence of Mn-oxidizing/reducing bacteria in the (mycor)rhizosphere was unrelated to Mn toxicity in plants. Using 16S rDNA sequence homologies, the Mn-reducing isolates were consistent with the genus Streptomyces. The Mn-oxidizers were homologous with the genera Arthrobacter, Variovorax and Ralstonia. While CP1 plants showed Mn toxicity throughout the whole growth period, CP2 plants never did, in spite of having Fe and Mn shoot concentrations as high as in CP1 plants. Mycorrhizal plants showed Mn toxicity symptoms early in the growth period that were no longer visible in later growth stages. The shoot P concentration was almost twice as high in mycorrhizal plants compared with CP1 and CP2 plants. The shoot Mn and Fe concentrations and contents were lower in GmP1 and GeP1 plants compared with the CP2 treatment, even though levels of extractable metals increased in the soil when plants were mycorrhizal. This suggests that mycorrhiza protected its host plant from excessive uptake of Mn and Fe. In addition, higher tissue P concentrations may have facilitated internal detoxification of Mn in mycorrhizal plants. The exact mechanisms acting on alleviation of Mn toxicity in mycorrhizal plants should be further investigated.

Genetic damage induced by trophic doses of lead in the neotropical fish Hoplias malabaricus (Characiformes, Erythrinidae) as revealed by the comet assay and chromosomal aberrations

Abstract: The effects of clastogenic or mutagenic agents have rarely been studied in neotropical fish species exposed to contaminated water. In this study, the genetic damage caused by lead in the widely distributed South American fish, Hoplias malabaricus, was assessed using the comet (SCGE) assay and by testing for chromosomal aberrations. Eighteen specimens were acclimatized to laboratory conditions and then chronically exposed to contaminated food by feeding prey (Cyprinus sp.) injected intraperitoneally with doses of inorganic lead adjusted to give a contamination level of 21 mg of Pb2+.g-1 net weight of H. malabaricus. Three fish were sampled for chromosomal analysis after four doses (18 days) and another three after eight doses (41 days) of lead and the results then compared with three untreated controls kept under lead-free conditions. An additional six treated fish and three controls were sampled for the comet assay after 13 doses (64 days). Exposure to lead significantly increased the frequency of chromosomal aberrations and the frequency of tailed cell nuclei, the latter indicating DNA damage. These results show that H. malabaricus is a useful biological model for screening the clastogenic effects of lead and possibly other xenobiotics. The genetic damage seen here illustrates the need to investigate the potential effects of heavy metals on fish species in South America.

Antiviral activity of aqueous and ethanol extracts and of an isolated polysaccharide from Agaricus brasiliensis against poliovirus type 1

Abstract: Aims: Agaricus brasiliensis (previously named Agaricus blazei ss. Heinem), also known as the sun mushroom is native of Southeast Brazil, and is widely consumed, mainly in the form of tea, due to its nutritional and pharmacological properties. In this study, we tested aqueous (AqE) and ethanol (EtOHE) extracts and an isolated polysaccharide (PLS) from the fruiting body of A. brasiliensis, for antiviral activity against poliovirus type 1 in HEp-2 cells. Methods and Results: The evaluation of the time of addition by plaque assay showed that when AqE, PLS and EtOHE were added, just after the virus inoculation (time 0 h), there was a concentration-dependent reduction in the number of plaques up to 50%, 67% and 88%, respectively, with a selectivity index (SI) of 5·4, 9·9 and 12·3, respectively. Conclusions: The test substances showed antiviral activity and were more effective when added during the poliovirus infection. As they had little effect on reducing viral adsorption and did not show any virucidal effect, we suggest that they act at the initial stage of the replication of poliovirus. Significance and Impact of the Study: These results corroborate that basidiomycetes can be a rich source of potential antiviral compounds.

Perfil sociodemográfico e de padrões de uso entre dependentes de cocaína hospitalizados

Abstract: OBJETIVO: Avaliar o perfil sociodemografico e o padrao de uso da cocaina entre usuarios de drogas hospitalizados. METODOS: Estudo transversal com dependentes quimicos maiores de 18 anos, internados em alguns hospitais psiquiatricos da regiao metropolitana da Grande Sao Paulo, Brasil, com condicoes clinicas de responder a questionario padronizado e que concordaram em participar do estudo. Foram selecionados seis hospitais psiquiatricos que recebiam, por procura espontânea, pacientes da rede publica e privada de toda a regiao da Grande Sao Paulo. A coleta de informacoes foi feita por meio de entrevistas estruturadas, aplicada individualmente por psicologa treinada. Para analise estatistica utilizou-se do teste t de Sudent e Qui-quadrado, e o nivel de significância foi fixado em 5%. RESULTADOS: Encontrou-se maior taxa (38,4%) de usuarios de crack e pequena prevalencia (1,6%) de usuarios de drogas injetaveis. Os dependentes de cocaina fumada apresentavam baixa escolaridade, encontravam-se mais frequentemente desempregados, haviam morado nas ruas, usavam maiores quantidades de droga e tinham sido presos em maior numero de vezes do que aqueles que usavam outras vias de administracao da droga. CONCLUSOES: Os resultados sugerem que o uso de drogas e um grave problema de saude publica na Grande Sao Paulo, mostrado pelo numero de internacoes hospitalares por dependencia. Os usuarios de crack apresentam pior condicao socioeconomica e maior envolvimento com a violencia e a criminalidade.