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.

Exploitation of immunofluorescence for the quantification and characterization of small numbers of Pasteuria endospores.

Hutchings, Michael J. Gibson, David J. Bardgett, Richard D. Rees, Mark Newton, Erika Baier, Andrea Sandhu, Lauren

https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2745.2011.01927.x

Tansley's vision for Journal of Ecology, and a Centenary Celebration

This study aimed to determine the factors which regulate soil microbial community organisation and function in temperate upland grassland ecosystems Soil microbial biomass (Cmic), activity (respiration and potential carbon utilisation) and community structure (phospholipid fatty acid (PLFA) analysis, culturing and community level physiological profiles (CLPP) (Biolog®)) were measured across a gradient of three upland grassland types; Festuca–Agrostis–Galium grassland (unimproved grassland, National Vegetation Classification (NVC) — U4a); Festuca–Agrostis–Galium grassland, Holcus–Trifolium sub-community (semi-improved grassland, NVC — U4b); Lolium–Cynosurus grassland (improved grassland, NVC — MG6) at three sites in different biogeographic areas of the UK over a period of 1 year Variation in Cmic was mainly due to grassland type and site (accounting for 55% variance, v, in the data) Cmic was significantly (P<0001) high in the unimproved grassland at Torridon (2374 g C m−2 cf 812 g C m−2 in semi- and 638 g C m−2 in improved grasslands) and Sourhope (1146 g C m−2 cf in 448 g C m−2 semi- and 683 g C m−2 in improved grasslands) and semi-improved grassland at Abergwyngregyn (760 g C m−2 cf 417 g C m−2 in un- and 583 g C m−2 in improved grasslands) Cmic showed little temporal variation (v=37%) Soil microbial activity, measured as basal respiration was also mainly affected by grassland type and site (n=32%) In contrast to Cmic, respiration was significantly (P<0001) high in the improved grassland at Sourhope (2634 l h−1m−2 cf 796 l h−1m−2 in semi- and 2039 l h−1m−2 unimproved grasslands) and Abergwyngregyn (1988 l h−1m−2 cf 1737 l h−1m−2 in semi- and 882 l h−1m−2 unimproved grasslands) Microbial activity, measured as potential carbon utilisation, agreed with the respiration measurements and was significantly (P<0001) high in the improved grassland at all three sites (A590 014 cf 009 in semi- and 007 in unimproved grassland) However, date of sampling also had a significant (P<0001) impact on C utilisation potential (v=247%) with samples from April 1997 having highest activity at all three sites Variation in microbial community structure was due, predominantly, to grassland type (average v=236% for bacterial and fungal numbers and PLFA) and date of sampling (average v=397% for bacterial and fungal numbers and PLFA) Numbers of culturable bacteria and bacterial PLFA were significantly (P<0001) high in the improved grassland at all three sites Fungal populations were significantly (P<001) high in the unimproved grassland at Sourhope and Abergwyngregyn The results demonstrate a shift in soil microbial community structure from one favouring fungi to one favouring bacteria as grassland improvement increased Numbers of bacteria and fungi were also significantly (P<0001) higher in August than any other sampling date Canonical variate analysis (CVA) of the carbon utilisation data significantly (P<005) differentiated microbial communities from the three grassland types, mainly due to greater utilisation of sugars and citric acid in the improved grasslands compared to greater utilisation of carboxylic acids, phenolics and neutral amino acids in the unimproved grasslands, possibly reflecting substrate availability in these grasslands Differences in Cmic, activity and community structure between grassland types were robust over time In addition, broad scale measures of microbial growth and activity (Cmic and respiration) showed little temporal variation compared to measures of soil microbial community structure, which varied quantitatively with respect to environmental variables (temperature, moisture) and plant productivity, hence substrate supply

Accounting for variability in soil microbial communities of temperate upland grasslands.

Boreal forests occupy nearly one fifth of the terrestrial land surface and are recognised as globally important regulators of carbon (C) cycling and greenhouse gas emissions. Carbon sequestration processes in these forests include assimilation of CO2 into biomass and subsequently into soil organic matter, and soil microbial oxidation of methane (CH4). In this study we explored how ecosystem retrogression, which drives vegetation change, regulates the important process of soil CH4 oxidation in boreal forests. We measured soil CH4 oxidation processes on a group of 30 forested islands in northern Sweden differing greatly in fire history, and collectively representing a retrogressive chronosequence, spanning 5000 years. Across these islands the build-up of soil organic matter was observed to increase with time since fire disturbance, with a significant correlation between greater humus depth and increased net soil CH4 oxidation rates. We suggest that this increase in net CH4 oxidation rates, in the absence of disturbance, results as deeper humus stores accumulate and provide niches for methanotrophs to thrive. By using this gradient we have discovered important regulatory controls on the stability of soil CH4 oxidation processes that could not have not been explored through shorter-term experiments. Our findings indicate that in the absence of human interventions such as fire suppression, and with increased wildfire frequency, the globally important boreal CH4 sink could be diminished.

/pdf/soil-methane-sink-capacity-response-to-a-long-term-wildfire-489kxix3f1.pdf

Richard D. Bardgett

Papers

Exploitation of immunofluorescence for the quantification and characterization of small numbers of Pasteuria endospores.

Tansley's vision for Journal of Ecology, and a Centenary Celebration

Accounting for variability in soil microbial communities of temperate upland grasslands.

Soil methane sink capacity response to a long-term wildfire chronosequence in northern Sweden

Microbial biomass and activity in a grassland soil amended with different application rates of silage effluent—A laboratory study