Prospecção de microrganismos antagonistas para biocontrole de Colletotrichum sublineolum, agente causal da antracnose do sorgo.

A antracnose é considerada a doença que mais afeta economicamente a cultura do sorgo no Brasil. Apresenta como agente causal o fungo Colletotrichum sublineolum, que ataca todas as partes da planta. O objetivo do trabalho foi selecionar isolados de bactérias e actinobactérias com potencial antagonista para o biocontrole de C. sublineolum. Foram testados in vitro 80 microrganismos por meio do método de culturas pareadas. Os maiores índices de inibição foram apresentados pelos isolados B.1433 (85%), Act.9 (80%) e Act.336(80%). Após a pré-seleção dos isolados, avaliou-se a influência do metabólito desses microrganismos sobre a germinação e o crescimento micelial de C. sublineolum em meio sólido e em meio líquido, respectivamente. Em meio sólido, a germinação de esporos foi inibida pelos três isolados, entretanto, a inibição do crescimento em meio líquido não foi significativa. Os isolados B.1433, Act.09 e Act.336 apresentaram potencial in vitro quanto à viabilidade de utilização no biocontrole de C. sublineolum.bitstream/item/95419/1/bol-74.pd

Seleção de microrganismos antagonistas para biocontrole de Fusarium verticillioides na cultura do milho (Zea mays L.).

O objetivo do trabalho foi selecionar e analisar estirpes de bactérias e actinomicetos com potencial antagonista para o biocontrole do Fusarium verticillioides, causador de doenças na cultura do milho. O potencial antagonista de 80 isolados, de bactérias e actinomicetos, foi avaliado in vitro por meio do método de culturas pareadas. Dentre os isolados avaliados, foram selecionados Act.336, B.1433 e Act.9, devido aos maiores índices de inibição contra o fitopatógeno, com valores de 66,9%, 53,1% e 51,9%, respectivamente. A seguir, avaliou-se a influência de metabólitos produzidos por estes microrganismos para a inibição do crescimento micelial fúngico em meio líquido e germinação de conídios do patógeno em meio sólido. Estes isolados pré-selecionados apresentaram efeito antagonista contra o crescimento micelial. Entretanto, em meio sólido, somente os isolados Act.336 e Act.9 inibiram a germinação de conídios do fitopatógeno. Os três isolados apresentaram, in vitro, potencial para uso como antagonista de F. verticillioides.bitstream/item/94390/1/bol-75.pd

Bactérias endofíticas de milho: diversidade e potencial para solubilização de fosfato.

FertBio 2016

The conservative physiology of the immune system

Current immunological opinion disdains the necessity to define global interconnections between lymphocytes and regards natural autoantibodies and autoreactive T cells as intrinsically pathogenic. Immunological theories address the recognition of foreignness by independent clones of lymphocytes, not the relations among lymphocytes or between lymphocytes and the organism. However, although extremely variable in cellular/molecular composition, the immune system preserves as invariant a set of essential relations among its components and constantly enacts contacts with the organism of which it is a component. These invariant relations are reflected, for example, in the life-long stability of profiles of reactivity of immunoglobulins formed by normal organisms (natural antibodies). Oral contacts with dietary proteins and the intestinal microbiota also result in steady states that lack the progressive quality of secondary-type reactivity. Autoreactivity (natural autoantibody and autoreactive T cell formation) is also stable and lacks the progressive quality of clonal expansion. Specific immune responses, currently regarded as the fundament of the operation of the immune system, may actually result from transient interruptions in this stable connectivity among lymphocytes. More permanent deficits in interconnectivity result in oligoclonal expansions of T lymphocytes, as seen in Omenn's syndrome and in the experimental transplantation of a suboptimal diversity of syngeneic T cells to immunodeficient hosts, which also have pathogenic consequences. Contrary to theories that forbid autoreactivity as potentially pathogenic, the physiology of the immune system is conservative and autoreactive. Pathology derives from failures of these conservative mechanisms

Hippopotamus and livestock grazing:influences on riparian vegetation and facilitation of other herbivores in the Mara Region of Kenya

<p>Riparian savanna habitats grazed by hippopotamus or livestock experience seasonal ecological stresses through the depletion of herbaceous vegetation, and are often points of contacts and conflicts between herbivores, humans and their livestock. We investigated how hippopotamus and livestock grazing influence vegetation structure and cover and facilitate other wild herbivores in the Mara region of Kenya. We used 5 km-long transects, each with 13 plots measuring 10 x 10 m(2), and which radiate from rivers in the Masai Mara National Reserve and adjoining community pastoral ranches. For each plot, we measured the height and visually estimated the percent cover of grasses, forbs, shrubs and bare ground, herbivore abundance and species richness. Our results showed that grass height was shortest closest to rivers in both landscapes, increased with increasing distance from rivers in the reserve, but was uniformly short in the pastoral ranches. Shifting mosaics of short grass lawns interspersed with patches of medium to tall grasses occurred within 2.5 km of the rivers in the reserve in areas grazed habitually by hippos. Hence, hippo grazing enhanced the structural heterogeneity of vegetation but livestock grazing had a homogenizing effect in the pastoral ranches. The distribution of biomass and the species richness of other ungulates with distance from rivers followed a quadratic pattern in the reserve, suggesting that hippopotamus grazing attracted more herbivores to the vegetation patches at intermediate distances from rivers in the reserve. However, the distribution of biomass and the species richness of other ungulates followed a linear pattern in the pastoral ranches, implying that herbivores avoided areas grazed heavily by livestock in the pastoral ranches, especially near rivers.</p>

High rate of prey consumption in a small predatory fish on coral reefs.

Small piscivores are regarded as important regulators of the composition of coral reef fish communities, but few studies have investigated their predatory ecology or impact on assemblages of juvenile fishes. This study investigated the foraging ecology of a common coral reef predator, the dottyback Pseudochromis fuscus, using underwater focal animal observations. Observations were conducted at two times of year: the summer, when recruit fishes were an available food item and winter, when remaining juveniles had outgrown vulnerability to P. fuscus. During the summer, P. fuscus directed 76% of its strikes at invertebrates and 24% at recruiting juvenile fishes. When striking at fishes, P. fuscus exhibited two distinct feeding modes: an ambush (26% successful) and a pursuit mode (5% successful). Predator activity in the field peaked at midday, averaging 2.5 captures h⁻¹ of juvenile fishes. Monitoring of activity and foraging in the laboratory over 24-h periods found that P. fuscus was a diurnal predator and was active for 13 h d-1 during the summer. The number of hours during which foraging was recorded differed greatly among individuals (n = 10), ranging from 4 to 13 h. The number of predatory strikes did not increase with standard length, but the success rate and consumption rate of juvenile fishes did increase with size. Estimated hourly mortality on juvenile fish ranged from 0.49 fish h-1 in small P. fuscus individuals (30–39 mm standard length, SL; equating to 6.3 per 13 h day) to 2.4 fish h⁻¹ in large P. fuscus individuals (55–65 mm SL; 30.6 per 13 h day). During the winter, P. fuscus struck at invertebrates with a similar rate to the summer period. These observations of the predatory ecology of P. fuscus support the hypothesis that in coral reef systems, small piscivores, because of their high metabolism and activity, are probably important regulators of coral reef fish community composition