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

Drafting Authors: Neil Adger, Pramod Aggarwal, Shardul Agrawala, Joseph Alcamo, Abdelkader Allali, Oleg Anisimov, Nigel Arnell, Michel Boko, Osvaldo Canziani, Timothy Carter, Gino Casassa, Ulisses Confalonieri, Rex Victor Cruz, Edmundo de Alba Alcaraz, William Easterling, Christopher Field, Andreas Fischlin, Blair Fitzharris, Carlos Gay García, Clair Hanson, Hideo Harasawa, Kevin Hennessy, Saleemul Huq, Roger Jones, Lucka Kajfež Bogataj, David Karoly, Richard Klein, Zbigniew Kundzewicz, Murari Lal, Rodel Lasco, Geoff Love, Xianfu Lu, Graciela Magrín, Luis José Mata, Roger McLean, Bettina Menne, Guy Midgley, Nobuo Mimura, Monirul Qader Mirza, José Moreno, Linda Mortsch, Isabelle Niang-Diop, Robert Nicholls, Béla Nováky, Leonard Nurse, Anthony Nyong, Michael Oppenheimer, Jean Palutikof, Martin Parry, Anand Patwardhan, Patricia Romero Lankao, Cynthia Rosenzweig, Stephen Schneider, Serguei Semenov, Joel Smith, John Stone, Jean-Pascal van Ypersele, David Vaughan, Coleen Vogel, Thomas Wilbanks, Poh Poh Wong, Shaohong Wu, Gary Yohe

Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change

From molecules to crystal engineering: supramolecular isomerism and polymorphism in network solids.

The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. 
The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. 
The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. 
The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

Influence of Diet On the Distribtion of Nitrogen Isotopes in Animals

Black carbon aerosol plays a unique and important role in Earth's climate system. Black carbon is a type of carbonaceous material with a unique combination of physical properties. This assessment provides an evaluation of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice. These effects are calculated with climate models, but when possible, they are evaluated with both microphysical measurements and field observations. Predominant sources are combustion related, namely, fossil fuels for transportation, solid fuels for industrial and residential uses, and open burning of biomass. Total global emissions of black carbon using bottom-up inventory methods are 7500 Gg yr−1 in the year 2000 with an uncertainty range of 2000 to 29000. However, global atmospheric absorption attributable to black carbon is too low in many models and should be increased by a factor of almost 3. After this scaling, the best estimate for the industrial-era (1750 to 2005) direct radiative forcing of atmospheric black carbon is +0.71 W m−2 with 90% uncertainty bounds of (+0.08, +1.27) W m−2. Total direct forcing by all black carbon sources, without subtracting the preindustrial background, is estimated as +0.88 (+0.17, +1.48) W m−2. Direct radiative forcing alone does not capture important rapid adjustment mechanisms. A framework is described and used for quantifying climate forcings, including rapid adjustments. The best estimate of industrial-era climate forcing of black carbon through all forcing mechanisms, including clouds and cryosphere forcing, is +1.1 W m−2 with 90% uncertainty bounds of +0.17 to +2.1 W m−2. Thus, there is a very high probability that black carbon emissions, independent of co-emitted species, have a positive forcing and warm the climate. We estimate that black carbon, with a total climate forcing of +1.1 W m−2, is the second most important human emission in terms of its climate forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing. Sources that emit black carbon also emit other short-lived species that may either cool or warm climate. Climate forcings from co-emitted species are estimated and used in the framework described herein. When the principal effects of short-lived co-emissions, including cooling agents such as sulfur dioxide, are included in net forcing, energy-related sources (fossil fuel and biofuel) have an industrial-era climate forcing of +0.22 (−0.50 to +1.08) W m−2 during the first year after emission. For a few of these sources, such as diesel engines and possibly residential biofuels, warming is strong enough that eliminating all short-lived emissions from these sources would reduce net climate forcing (i.e., produce cooling). When open burning emissions, which emit high levels of organic matter, are included in the total, the best estimate of net industrial-era climate forcing by all short-lived species from black-carbon-rich sources becomes slightly negative (−0.06 W m−2 with 90% uncertainty bounds of −1.45 to +1.29 W m−2). The uncertainties in net climate forcing from black-carbon-rich sources are substantial, largely due to lack of knowledge about cloud interactions with both black carbon and co-emitted organic carbon. In prioritizing potential black-carbon mitigation actions, non-science factors, such as technical feasibility, costs, policy design, and implementation feasibility play important roles. The major sources of black carbon are presently in different stages with regard to the feasibility for near-term mitigation. This assessment, by evaluating the large number and complexity of the associated physical and radiative processes in black-carbon climate forcing, sets a baseline from which to improve future climate forcing estimates.

/pdf/bounding-the-role-of-black-carbon-in-the-climate-system-a-1fc3novd9r.pdf

Bounding the role of black carbon in the climate system: A scientific assessment

The tropical atmospheric circulation is strongly influenced by the sea surface temperature (SST) of the warmest region of the world ocean, the Indo-Pacific Warm Pool (IPWP). The effect of recent anomalous Indian Ocean warming on the extent of the IPWP remains uncertain. Past SST records from the tropical Indian Ocean, associated with different temporal boundary conditions, can help shed light on how climate change impacts the IPWP and associated monsoonal processes. Here, we reconstruct the seawater temperature and precipitation changes (from Mg/Ca and δ18O of surface-dwelling planktic foraminifera Globigerinoides ruber) of the last ~184 kyr BP from the westernmost margin of the IPWP. The data is then used to reconstruct the spatial extent and intensity of the IPWP structure as well as its relationship with other regional phenomena. A consistently warmer (>28 °C) central equatorial Pacific Ocean and significantly cooler equatorial western Pacific and the Indian Ocean suggests that the warm pool extent reduced considerably during MIS6 as well as the last glacial interval, leading to a strong La-Nina like condition. The most enriched seawater δ18O (δ18Osw) during MIS6, was in the westernmost IPWP, suggesting weakened precipitation, despite La-Lina like conditions. The westernmost part of the IPWP became warmer than the threshold 28 °C during MIS5e and the early Holocene, suggesting the westward extension of the IPWP. The eastern equatorial Pacific Ocean also warmed considerably during MIS5e, suggesting a weaker Walker Circulation and a stronger El-Nino. The difference in δ18Osw decreased considerably during MIS5e and is attributed to increased precipitation/freshwater runoff in the central equatorial Indian Ocean. The increase in δ18Osw (~1.5‰) between ~55 kyr until the last glacial maximum, in a majority of the Indian Ocean records, suggests progressively weakened precipitation. A majority of the records have a uniform SST anomaly throughout the Holocene. A warmer equatorial Indian Ocean during interglacials suggests a strong modulation of the IPWP extent by the transport of warm water through the Indonesian throughflow region. The large drop in δ18Osw despite the comparable change in SST during the last glacial interval suggests that monsoon forcing has been much stronger in altering the surface hydrography in the Indian Ocean than the central Pacific Ocean.

Indonesian throughflow controlled the westward extent of the Indo-Pacific Warm Pool during glacial-interglacial intervals

The distribution of Ba in the ocean is similar to the refractory components, silica and alkalinity. Therefore reconstructions of Ba in ancient water masses can be used to probe the circulation and chemistry of past oceans. Paleo-Ba distributions are recovered from the aragonite skeletons of corals and the calcite shells of planktonic and benthic foraminifera, since Ba substitutes for Ca in the lattice of these biogenic phases. The shell or coral material is treated with a rigorous cleaning procedure to remove spurious Ba associated with residual sedimentary phases. The Ba/Ca ratio of the purified foraminiferal calcite or coralline aragonite is quantified by a combination of isotope dilution flow injection on an ICP-MS for Ba and flame atomic absorption for Ca. A quarter-annual record of coralline Ba recovered from a cored sample of Pavona clavus from the Galapagos Islands demonstrates that variability in Ba can be related to temporal variability in upwelling of source waters to the surface ocean. Ba/Ca ratios vary between about 4 and 5 gmol/mol, with the highest values associated with bands formed during periods of cold sea surface temperatures. Upwelling in the equatorial Pacific transports cold, Ba-rich upper thermocline waters to the surface ocean, causing the coincidence between Ba and sea surface temperature. Depression of the thermocline during El Niio/Southern Oscillation (ENSO) events results in the coincidence of negative Ba anomalies with the positive temperature anomalies characteristic of ENSO events. Sr/Ca ratios in the same coral record vary between about 9.2 and 9.8 mmol/mol, presumably in response to a temperature effect on Sr incorporation. Similarities between Ba and Sr records in the coral suggest that the Ba/Ca ratio of corals may be partially controlled by a temperature effect. Planktonic foraminifera Globigerinoides sacculifera, ruber,conglobatus, Orbulina spp. and Neogloboquadrina dutertrei from the Panama Basin, North Atlantic, and Mediterranean have Ba/Ca ratios between 0.6 and 1.0 pmol/mol. Variation in foraminiferal Ba contents between the three basins is consistent with the trend in surface seawater Ba. The distribution coefficient for Ba incorporation in these 5 species is 0.19 + 0.05. Records of planktonic-Ba reaching back to the end of the last glacial period do not reveal any large change in the Ba concentration of North-West Atlantic and Eastern Equatorial Pacific surface waters. Globorotalia have Ba/Ca ratios as high as 10 i±mol/mol; these anomalously high Ba contents are inconsistent with coprecipitation of Ba

Foraminiferal and coralline barium as paleoceanographic tracers

El Niño in history: Storming through the ages

Mg/Ca data from ODP Hole 806B on the Ontong Java Plateau, western equatorial Pacific, indicate that marine isotope stage (MIS) 11 was the warmest interglacial episode of the last 450 ky Sea surface temperatures (SSTs) for MIS 11, as calculated from Mg/Ca, reached just above 30°C MIS 11 is also characterized by the longest sustained period (-20 ky) of SST ≥ 29°C The maximum in MIS 11 SST is flanked by strong minima in SST (25 to 26°C) in glacial MIS 10 and 12 The changes in SST, as indicated by Mg/Ca, lead the changes in δ 18 O at the climate transitions by as much as 7-9 ky, suggesting that temperature changed before ice volume and/or local hydrology Warm tropical Pacific SST during MIS 11 is supported by uplifted reefs of coeval age containing warm-water fauna on the Chilean coast A super-interglacial in the tropical Pacific during MIS 11 would undoubtedly have influenced global climate through direct heat exchange and influence on atmospheric H 2 O and CO 2 

Sea Surface Temperatures in the Western Equatorial Pacific During Marine Isotope Stage 11

Much of the global annual mean temperature change over Quaternary glacial cycles can be attributed to slow ice sheet and greenhouse gas feedbacks, but analysis of the short-term response to orbital forcings has the potential to reveal key relationships in the climate system. In particular, obliquity and precession both produce highly seasonal temperature responses at high latitudes. Here, idealized single-forcing model experiments are used to quantify Earth’s response to obliquity, precession, CO2, and ice sheets, and a linear reconstruction methodology is used to compare these responses to long proxy records around the globe. This comparison reveals mismatches between the annual mean response to obliquity and precession in models versus the signals within Antarctic ice cores. Weighting the model-based reconstruction toward austral winter or spring reduces these discrepancies, providing evidence for a seasonal bias in ice cores. Periodic changes in the tilt of the Earth’s axis alter the distribution of incoming solar radiation. Here, the authors show that the temperature response to this forcing seemingly differs in models and Antarctic ice cores, with a better agreement reached if ice cores are recording a seasonally weighted signal.

/pdf/model-evidence-for-a-seasonal-bias-in-antarctic-ice-cores-280vjhdf4h.pdf

David W. Lea

Papers

Indonesian throughflow controlled the westward extent of the Indo-Pacific Warm Pool during glacial-interglacial intervals

Foraminiferal and coralline barium as paleoceanographic tracers

El Niño in history: Storming through the ages

Sea Surface Temperatures in the Western Equatorial Pacific During Marine Isotope Stage 11

Model evidence for a seasonal bias in Antarctic ice cores