Michigan State University

About: Michigan State University is a education organization based out in East Lansing, Michigan, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 60109 authors who have published 137074 publications receiving 5633022 citations. The organization is also known as: MSU & Michigan State.

Foraging Efficiency and Body Size: A Study of Optimal Diet and Habitat Use by Bluegills

Abstract: A foraging model was developed to predict the optimal diet breadth and maximum energetic intake of a given-sized fish foraging in each of three aquatic habitats: the open water, vegetation, and bare sediments. Model parameters of prey encounter rates and prey handling times were quantified as functions of fish size, prey density, and prey size through a series of laboratory feeding experiments using the bluegill sunfish (Lepomis macrochirus). Results of these experiments show both searching ability and prey handling efficiency to increase with increasing fish size. Predictions of prey size selection and optimal habitat use based upon maximizing energetic gain were then examined in a small Michigan lake for three size classes of bluegills. Bluegills >100 mm standard length were highly size selective in their feeding and their diets closely matched predictions of an optimal diet model. From two estimates of relative prey visibilities I show that these fish selected larger prey items than would be predicted if prey were consumed "as encountered." Habitat use of large bluegills was also shown to maximize foraging return as fish switched from utilizing vegetation- living prey to utilizing open-water zooplankton as relative foraging profitabilities in the two habitats changed across the summer. Bluegills < 100 mm standard length were restricted in their habitat use, remaining in or near the vegetation despite demonstrated increases in foraging return available in the open-water habitat. Size-related predation risk apparently accounts for differences in habitat use between bluegill size classes, and its consequences for intra- and interspecific competition between size classes are discussed.

Lactobacilli Differentially Modulate Expression of Cytokines and Maturation Surface Markers in Murine Dendritic Cells

Abstract: Dendritic cells (DC) play a pivotal immunoregulatory role in the Th1, Th2, and Th3 cell balance and are present throughout the gastrointestinal tract. Thus, DC may be targets for modulation by gut microbes, including ingested probiotics. In the present study, we tested the hypothesis that species of Lactobacillus, important members of the gut flora, differentially activate DC. Bone marrow-derived murine DC were exposed to various lethally irradiated Lactobacillus spp. and resultant culture supernatants were analyzed for IL-6, IL-10, IL-12, and TNF-alpha. Substantial differences were found among strains in the capacity to induce IL-12 and TNF-alpha production in the DC. Similar but less pronounced differences were observed among lactobacilli in the induction of IL-6 and IL-10. Although all strains up-regulated surface MHC class II and B7-2 (CD86), which is indicative of DC maturation, those lactobacilli with greatest capacity to induce IL-12 were most effective. Remarkably, Lactobacillus reuteri DSM12246, a poor IL-12 inducer, inhibited IL-12, IL-6, and TNF-alpha induction by the otherwise strong cytokine inducer L. casei CHCC3139, while IL-10 production remained unaltered. In analogous fashion, L. reuteri reduced L. casei-induced up-regulation of B7-2. These results suggest that different species of Lactobacillus exert very different DC activation patterns and, furthermore, at least one species may be capable of inhibiting activities of other species in the genus. Thus, the potential exists for Th1/Th2/Th3-driving capacities of the gut DC to be modulated according to composition of gut microflora, including ingested probiotics.

A global quantitative synthesis of local and landscape effects on wild bee pollinators in agroecosystems

Abstract: Bees provide essential pollination services that are potentially affected both by local farm management and the surrounding landscape. To better understand these different factors, we modelled the relative effects of landscape composition (nesting and floral resources within foraging distances), landscape configuration (patch shape, interpatch connectivity and habitat aggregation) and farm management (organic vs. conventional and local-scale field diversity), and their interactions, on wild bee abundance and richness for 39 crop systems globally. Bee abundance and richness were higher in diversified and organic fields and in landscapes comprising more high-quality habitats; bee richness on conventional fields with low diversity benefited most from high-quality surrounding land cover. Landscape configuration effects were weak. Bee responses varied slightly by biome. Our synthesis reveals that pollinator persistence will depend on both the maintenance of high-quality habitats around farms and on local management practices that may offset impacts of intensive monoculture agriculture.