抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Humans are altering the composition of biological communities through a variety of activities that increase rates of species invasions and species extinctions, at all scales, from local to global. These changes in components of the Earth's biodiversity cause concern for ethical and aesthetic reasons, but they also have a strong potential to alter ecosystem properties and the goods and services they provide to humanity. Ecological experiments, observations, and theoretical developments show that ecosystem properties depend greatly on biodiversity in terms of the functional characteristics of organisms present in the ecosystem and the distribution and abundance of those organisms over space and time. Species effects act in concert with the effects of climate, resource availability, and disturbance regimes in influencing ecosystem properties. Human activities can modify all of the above factors; here we focus on modification of these biotic controls. The scientific community has come to a broad consensus on many aspects of the re- lationship between biodiversity and ecosystem functioning, including many points relevant to management of ecosystems. Further progress will require integration of knowledge about biotic and abiotic controls on ecosystem properties, how ecological communities are struc- tured, and the forces driving species extinctions and invasions. To strengthen links to policy and management, we also need to integrate our ecological knowledge with understanding of the social and economic constraints of potential management practices. Understanding this complexity, while taking strong steps to minimize current losses of species, is necessary for responsible management of Earth's ecosystems and the diverse biota they contain.

/pdf/effects-of-biodiversity-on-ecosystem-functioning-a-consensus-13j8vabcus.pdf

Effects of biodiversity on ecosystem functioning: a consensus of current knowledge

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Modern Applied Statistics With S

The most unique feature of Earth is the existence of life, and the most extraordinary feature of life is its diversity. Approximately 9 million types of plants, animals, protists and fungi inhabit the Earth. So, too, do 7 billion people. Two decades ago, at the first Earth Summit, the vast majority of the world's nations declared that human actions were dismantling the Earth's ecosystems, eliminating genes, species and biological traits at an alarming rate. This observation led to the question of how such loss of biological diversity will alter the functioning of ecosystems and their ability to provide society with the goods and services needed to prosper.

/pdf/biodiversity-loss-and-its-impact-on-humanity-2d0fgc88mg.pdf

Biodiversity loss and its impact on humanity

Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

/pdf/climate-change-2007-the-physical-science-basis-1x93ttz9jt.pdf

Climate Change 2007: The Physical Science Basis.

Improving the predictive power and interdisciplinarity of climate change experiments

Earth Matters: How soil underlies civilization

Abstract Interactions between soil organic matter and minerals largely govern the carbon sequestration capacity of soils. Yet, variations in the proportions of free light (unprotected) and mineral-associated (protected) carbon as soil develops in contrasting ecosystems are poorly constrained. Here, we studied 16 long-term chronosequences from six continents and found that the ecosystem type is more important than soil age (centuries to millennia) in explaining the proportion of unprotected and mineral-associated carbon fractions in surface soils across global biomes. Soil carbon pools in highly productive tropical and temperate forests were dominated by the unprotected carbon fraction and were highly vulnerable to reductions in ecosystem productivity and warming. Conversely, soil carbon in low productivity, drier and colder ecosystems was dominated by mineral-protected carbon, and was less responsive to warming. Our findings emphasize the importance of conserving ecosystem productivity to protect carbon stored in surface soils. 

/pdf/ecosystem-productivity-has-a-stronger-influence-than-soil-2lmstlcu.pdf

Ecosystem productivity has a stronger influence than soil age on surface soil carbon storage across global biomes

Quarries and minesites are examples of extreme disturbance. Frequently, materials that form soil are scarce and ecological restoration is easier to achieve than productive land. Establishment of soil microbial function is critical to ecological restoration and a key objective of the study. An organic fertilizer containing a mix of sewage and paper sludges was designed to promote soil functioning during the revegetation of slate waste. We compared soil formation under naturally established birch trees (Betula pubescens) on slate waste with that of container-grown seedling birches of local provenance in slate waste amended with either organic or mineral fertilizer. Hypotheses that an organic nutrient source would lead to more rapid establishment of microbial communities and nutrient cycling than mineral fertilizer, and result in a substrate biochemically comparable to that under naturally established revegetation, were supported.

Richard D. Bardgett

Papers

Improving the predictive power and interdisciplinarity of climate change experiments

Earth Matters: How soil underlies civilization

Ecosystem productivity has a stronger influence than soil age on surface soil carbon storage across global biomes

Soil functioning in natural and planted woodlands on slate waste

Grassland belowground feedbacks and climate change