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

Since 65 million years ago (Ma), Earth's climate has undergone a significant and complex evolution, the finer details of which are now coming to light through investigations of deep-sea sediment cores. This evolution includes gradual trends of warming and cooling driven by tectonic processes on time scales of 10(5) to 10(7) years, rhythmic or periodic cycles driven by orbital processes with 10(4)- to 10(6)-year cyclicity, and rare rapid aberrant shifts and extreme climate transients with durations of 10(3) to 10(5) years. Here, recent progress in defining the evolution of global climate over the Cenozoic Era is reviewed. We focus primarily on the periodic and anomalous components of variability over the early portion of this era, as constrained by the latest generation of deep-sea isotope records. We also consider how this improved perspective has led to the recognition of previously unforeseen mechanisms for altering climate.

/pdf/trends-rhythms-and-aberrations-in-global-climate-65-ma-to-cflhxkixnq.pdf

Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present

Rising atmospheric carbon dioxide (CO2), primarily from human fossil fuel combustion, reduces ocean pH and causes wholesale shifts in seawater carbonate chemistry. The process of ocean acidification is well documented in field data, and the rate will accelerate over this century unless future CO2 emissions are curbed dramatically. Acidification alters seawater chemical speciation and biogeochemical cycles of many elements and compounds. One well-known effect is the lowering of calcium carbonate saturation states, which impacts shell-forming marine organisms from plankton to benthic molluscs, echinoderms, and corals. Many calcifying species exhibit reduced calcification and growth rates in laboratory experiments under high-CO2 conditions. Ocean acidification also causes an increase in carbon fixation rates in some photosynthetic organisms (both calcifying and noncalcifying). The potential for marine organisms to adapt to increasing CO2 and broader implications for ocean ecosystems are not well known; both are high priorities for future research. Although ocean pH has varied in the geological past, paleo-events may be only imperfect analogs to current conditions.

/pdf/ocean-acidification-the-other-co-2-problem-4h18mw2cpj.pdf

Ocean Acidification: The Other CO 2 Problem

We present here a new solution for the astronomical computation of the insolation quantities on Earth spanning from -250 Myr to 250 Myr. This solution has been improved with respect to La93 (Laskar et al. [CITE]) by using a direct integration of the gravitational equations for the orbital motion, and by improving the dissipative contributions, in particular in the evolution of the Earth–Moon System. The orbital solution has been used for the calibration of the Neogene period (Lourens et al.  [CITE]), and is expected to be used for age calibrations of paleoclimatic data over 40 to 50 Myr, eventually over the full Palaeogene period (65 Myr) with caution. Beyond this time span, the chaotic evolution of the orbits prevents a precise determination of the Earth's motion. However, the most regular components of the orbital solution could still be used over a much longer time span, which is why we provide here the solution over 250 Myr. Over this time interval, the most striking feature of the obliquity solution, apart from a secular global increase due to tidal dissipation, is a strong decrease of about 0.38 degree in the next few millions of years, due to the crossing of the  resonance (Laskar et al. [CITE]). For the calibration of the Mesozoic time scale (about 65 to 250 Myr), we propose to use the term of largest amplitude in the eccentricity, related to , with a fixed frequency of /yr, corresponding to a period of 405 000 yr. The uncertainty of this time scale over 100 Myr should be about , and  over the full Mesozoic era.

/pdf/a-long-term-numerical-solution-for-the-insolation-quantities-4jg807k9xu.pdf

A long-term numerical solution for the insolation quantities of the Earth

Past episodes of greenhouse warming provide insight into the coupling of climate and the carbon cycle and thus may help to predict the consequences of unabated carbon emissions in the future.

/pdf/an-early-cenozoic-perspective-on-greenhouse-warming-and-yffl0bpyf1.pdf

An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2020PA004053

Bentho-Pelagic Decoupling: The Marine Biological Carbon Pump During Eocene Hyperthermals

Calculating surface water PCO2 from foraminiferal organic δ13C

Data report : stable isotopic stratigraphy of the Paleogene pelagic cap at Site 865, Allison Guyot : Northwest Pacific atolls and guyots

Deep-sea benthic foraminiferal turnover during the early–middle Eocene transition at Walvis Ridge (SE Atlantic)

How oxygen levels in Earth's atmosphere and oceans evolved has always been a central question in Earth System Science. Researchers have developed numerous tracers to tackle this question, utilizing geochemical characteristics of different elements. Iodine incorporated in calcium carbonate (including biogenic) minerals, reported as I/Ca, is a proxy for dissolved oxygen in seawater. Here we review the rationale behind this proxy, its recent applications and some potential future research directions.

/pdf/earth-history-of-oxygen-and-the-iproxy-u3nvh33gbo.pdf

Ellen Thomas

Papers

Bentho-Pelagic Decoupling: The Marine Biological Carbon Pump During Eocene Hyperthermals

Calculating surface water PCO2 from foraminiferal organic δ13C

Data report : stable isotopic stratigraphy of the Paleogene pelagic cap at Site 865, Allison Guyot : Northwest Pacific atolls and guyots

Deep-sea benthic foraminiferal turnover during the early–middle Eocene transition at Walvis Ridge (SE Atlantic)

Earth History of Oxygen and the iprOxy