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

Imagined communities: Reflections on the origin and spread of nationalism

The COVID-19 pandemic represents a massive global health crisis. Because the crisis requires large-scale behaviour change and places significant psychological burdens on individuals, insights from the social and behavioural sciences can be used to help align human behaviour with the recommendations of epidemiologists and public health experts. Here we discuss evidence from a selection of research topics relevant to pandemics, including work on navigating threats, social and cultural influences on behaviour, science communication, moral decision-making, leadership, and stress and coping. In each section, we note the nature and quality of prior research, including uncertainty and unsettled issues. We identify several insights for effective response to the COVID-19 pandemic and highlight important gaps researchers should move quickly to fill in the coming weeks and months.

/pdf/using-social-and-behavioural-science-to-support-covid-19-25vr5kyvxt.pdf

Using social and behavioural science to support COVID-19 pandemic response.

Disease-suppressive soils are exceptional ecosystems in which crop plants suffer less from specific soil-borne pathogens than expected owing to the activities of other soil microorganisms. For most disease-suppressive soils, the microbes and mechanisms involved in pathogen control are unknown. By coupling PhyloChip-based metagenomics of the rhizosphere microbiome with culture-dependent functional analyses, we identified key bacterial taxa and genes involved in suppression of a fungal root pathogen. More than 33,000 bacterial and archaeal species were detected, with Proteobacteria, Firmicutes, and Actinobacteria consistently associated with disease suppression. Members of the γ-Proteobacteria were shown to have disease-suppressive activity governed by nonribosomal peptide synthetases. Our data indicate that upon attack by a fungal root pathogen, plants can exploit microbial consortia from soil for protection against infections.

http://science.sciencemag.org/content/sci/332/6033/1097.full.pdf

Deciphering the Rhizosphere Microbiome for Disease-Suppressive Bacteria

We present a model of radicalization and deradicalization based on the notion that the quest for personal significance constitutes a major motivational force that may push individuals toward violent extremism. Radicalization is defined as the process of supporting or engaging in activities deemed (by others) as in violation of important social norms (e.g., the killing of civilians). In these terms, radicalization (1) is a matter of degree (in which mere attitudinal support for violence reflects a lower degree of radicalization than actual engagement in violence); (2) represents a subjective judgment proffered by those for whom the violated norms seem important but not by those who have devalued or suppressed the norms in question.

Our radicalization/deradicalization model contains three crucial components: (1) the motivational component (the quest for personal significance) that defines a goal to which one may be committed, (2) the ideological component that in addition identifies the means of violence as appropriate for this goal's pursuit, and (3) the social process of networking and group dynamics through which the individual comes to share in the violence-justifying ideology and proceeds to implement it as a means of significance gain. We present empirical evidence consistent with our model's assumptions and discuss its implications for policies of preventing radicalization and effecting deradicalization.

The Psychology of Radicalization and Deradicalization: How Significance Quest Impacts Violent Extremism

Cultural ‘Tightness-Looseness’：A Multilevel Theory

Users of online communities become more intimate in time by writing posts and exchanging comments to each other. Although a certain level of intimacy among a group of members can be beneficial for the activity of the whole community, too strong intimacy among existing members can make newcomers feel alienated, driving them to leave the community. In this letter, we introduce a growing network model in which we systematically study the effect of member intimacy on the formation of connected component of the network. We introduce a parameter called clinginess and control how the member intimacy affects the communication activity. We observe that cumulative number of users who leave the community exhibits a transition-like behavior, similarly to the discontinuous transition in statistical mechanics models. Implication of our result in constructing a sustainable online community is also discussed.

http://iopscience.iop.org/article/10.1209/0295-5075/118/48004/pdf

Kibum Kim

Papers

Cultural ‘Tightness-Looseness’：A Multilevel Theory

Structural phase transition in a growing network model with tunable member intimacy