			Home About us Contact

Many Interactions (many + interaction)

Distribution by Scientific Domains

Medical Sciences	50%
Life Sciences	50%

Selected Abstracts

Effects of environmental perturbations on abundance of subarctic plants after three, seven and ten years of treatments

ECOGRAPHY, Issue 1 2001
Enrico Graglia
Analyses of changes in vegetation were carried out after three, seven and ten years of fertilizer addition, warming and light attenuation in two subarctic, alpine dwarf shrub heaths. One site was just above the tree line, at ca 450 m a.s.l., and the other at a much colder fell-field at ca 1150 m altitude. The aim was to investigate how the treatments affected the abundance of different species and growth forms over time, including examinations of transient changes. Grasses, which increased in abundance by fertilizer addition, and cryptogams, which, by contrast, decreased by fertilizer addition and warming, were the most sensitive functional groups to the treatments at both sites. Nutrient addition exerted a stronger and more consistent effect than both shading and warming. Warming at the fell-field had slightly greater effect than at the warmer tree line with an increase in deciduous shrubs. The decreased abundance of mosses and lichens to fertilizer addition and/or warming was most likely an indirect treatment effect, caused by competition through increased abundance and overgrowth of grasses. Such changes in species composition are likely to alter decomposition rates and the water and energy exchange at the soil surface. We observed few, if any, transient effects of declining responses during the 10 yr of treatments. Instead, there were many cumulative effects of the treatments for all functional groups and many interactions between time and treatment, suggesting that once a change in community composition is triggered, it will continue with unchanged or accelerated rate for a long period of time. [source]

Phenology, ontogeny and the effects of climate change on the timing of species interactions

ECOLOGY LETTERS, Issue 1 2010
Louie H. Yang
Abstract Climate change is altering the phenology of many species and the timing of their interactions with other species, but the impacts of these phenological shifts on species interactions remain unclear. Classical approaches to the study of phenology have typically documented changes in the timing of single life-history events, while phenological shifts affect many interactions over entire life histories. In this study, we suggest an approach that integrates the phenology and ontogeny of species interactions with a fitness landscape to provide a common mechanistic framework for investigating phenological shifts. We suggest that this ontogeny,phenology landscape provides a flexible method to document changes in the relative phenologies of interacting species, examine the causes of these phenological shifts, and estimate their consequences for interacting species. Ecology Letters (2010) 13: 1,10 [source]

The CD200 and CD200 receptor cell surface proteins interact through their N-terminal immunoglobulin-like domains

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2004
Deborah Hatherley
Abstract CD200 (OX2) is a broadly distributed cell surface glycoprotein that interacts with a receptor on myeloid cells (CD200R) involved in regulation of macrophage function. Both CD200 and CD200R contain two Ig superfamily domains like many other leukocyte membrane proteins. Site-directed mutagenesis of CD200R showed that, like CD200, it interacted through its N-terminal domain. This indicated that the cell-cell interaction spans four Ig superfamily domains and this distance is similar to many interactions found between T,cells and antigen-presenting cells. This suggests that this topology is also important in interactions of CD200 on a variety of cells with CD200R on myeloid cells, and comparable contact sites may be important mediating regulation in other cell-cell interactions. The mutagenesis showed that the binding involved the predicted GFCC, face of its N-terminal domain, like that of CD200, suggesting that the interaction evolved from a homotypic interaction. [source]

Trans Fatty Acids, Insulin Resistance, and Type 2 Diabetes

NUTRITION REVIEWS, Issue 8 2006
Andrew O. Odegaard BA
Type 2 diabetes, a growing global health problem, has a complex etiology involving many interactions between genetic and environmental factors. Essential to the development of the disease is insulin resistance of the peripheral tissues. Insulin resistance may be partly modified by the specific types of dietary fatty acids. Trans fatty acids (TFAs), created through the transformation of polyunsaturated fatty acids from their natural cis form to the trans form, are abundant in the Western diet. TFAs take on similar properties as saturated fats, and appear to be more atherogenic. High intakes of saturated fats may promote insulin resistance. It is therefore reasonable to hypothesize that high intakes of TFAs would have similar, or stronger, effects. In this review, all current evidence on the topic of TFAs, insulin resistance, and type 2 diabetes is summarized and interpreted. Although there is some support from observational and experimental studies for the hypothesis that high intakes of TFAs may increase the risk for type 2 diabetes, inconsistencies across studies and methodological problems make it premature to draw definitive conclusions at this time. More experimental research in humans is needed to further address this question. [source]