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.

Root colonization and spore abundance of arbuscular mycorrhizal fungi in distinct successional stages from an Atlantic rainforest biome in southern Brazil

Abstract: The influence of plant functional groups and moderate seasonality on arbuscular mycorrhizal (AM) fungal status (root colonization and spore density) was investigated during 13 consecutive months in a chronosequence of succession in southern Brazil, consisting of grassland field, scrub vegetation, secondary forest and mature forest, in a region of transition from tropical to subtropical zones. AM root colonization and spore density decreased with advancing succession and were highest in early successional sites with grassland and scrub vegetation, intermediary in the secondary forest and lowest in the mature forest. They were little influenced by soil properties, but were sufficiently influenced by the fine root nutrient status and fine root traits among different functional plant groups. AM root colonization and spore density were higher during the favourable plant growth season (spring and summer) than during the less favourable plant growth season (autumn and winter). Spore density displayed significant seasonal variation at all sites, whilst root colonization displayed significant seasonal variation in grassland, scrub and secondary forest, but not in mature forest. The data suggest that (1) different plant functional groups display different relationships with AM fungi, influencing their abundance differentially; (2) plant species from early successional phases are more susceptible to AM root colonization and maintain higher AM sporulation than late successional species; (3) fine root traits and nutrient status influence these AM fungal attributes; and (4) higher AM spore production and root colonization is associated with the season of higher light incidence and temperature, abundant water in soil and higher plant metabolic activity.

Resistência do solo à penetração e desenvolvimento do sistema radicular do milho (Zea mays) sob diferentes sistemas de manejo em um Latossolo Roxo

Abstract: As modificacoes estruturais causadas no solo pelos diferentes sistemas de manejo podem resultar em maior ou menor compactacao, que podera interferir na densidade do solo, na porosidade, na infiltracao de agua no solo e no desenvolvimento radicular das culturas. Assim, este trabalho teve como objetivo estudar, em condicoes de campo, os efeitos da estrutura, umidade e resistencia do solo a penetracao no desenvolvimento do sistema radicular do milho (Zea mays), sob sistema convencional (aracao mais grade niveladora ha mais de dez anos) e plantio direto (ha mais de vinte anos). As avaliacoes foram realizadas em um Latossolo Roxo argiloso, na regiao norte do estado do Parana - Brasil, cultivado com milho, no verao, e trigo, no inverno. Os resultados mostraram que valores de resistencia do solo a penetracao superiores a 3,5 MPa nao restringiram desenvolvimento radicular do milho, porem influenciaram a sua morfologia. O plantio direto apresentou melhores condicoes de continuidade estrutural para o desenvolvimento radicular do que o sistema convencional, tendo sido sua resistencia mais afetada pela distribuicao estrutural do que pela umidade do solo.

The citrus flavonone naringenin reduces lipopolysaccharide-induced inflammatory pain and leukocyte recruitment by inhibiting nf-κb activation

Abstract: Lipopolysaccharide (LPS) is the major structural component of Gram-negative bacteria cell wall and a highly pro-inflammatory toxin. Naringenin is found in Citrus fruits and exhibits antioxidant and anti-inflammatory properties through inhibition of NF-κB activation but its effects in LPS-induced inflammatory pain and leukocyte recruitment were not investigated yet. We investigated the effects of naringenin in mechanical hyperalgesia, thermal hyperalgesia and leukocyte recruitment induced by intraplantar injection of LPS in mice. We found that naringenin reduced hyperalgesia to mechanical and thermal stimuli, myeloperoxidase (MPO, a neutrophil and macrophage marker) and N-acetyl-β-D-glucosaminidase (NAG, a macrophage marker) activities, oxidative stress and cytokine (TNF-α, IL-1β, IL-6, and IL-12) production in the paw skin. In the peritoneal cavity, naringenin reduced neutrophil and mononuclear cell recruitment, and abrogated MPO and NAG activity, cytokine and superoxide anion production, and lipid peroxidation. In vitro, pre-treatment with naringenin inhibited superoxide anion and cytokine (TNF-α, IL-1β, IL-6, and IL-12) production by LPS-stimulated RAW 264.7 macrophages. Finally, we demonstrated that naringenin inhibited NF-κB activation in vitro and in vivo. Therefore, naringenin is a promising compound to treat LPS-induced inflammatory pain and leukocyte recruitment.