TNFR1 is essential for CD40, but not for lipopolysaccharide-induced sickness behavior and clock gene dysregulation

Autoimmune and infectious diseases are associated with behavioral changes referred to as sickness behavior syndrome (SBS). In autoimmunity, the generation of anti-self T lymphocytes and autoantibodies critically involves binding of CD40 ligand on T-cells to its receptor CD40 on B-cells, dendritic cells and macrophages. Activation of CD40 leads to production of proinflammatory cytokines and, as shown here, induces SBS. Here we report that these behavioral changes depend on the expression of tumor necrosis factor alpha receptor 1 (TNFR1), but not on interleukin-1 receptor 1 or interleukin-6. Moreover, the intensity of SBS correlates with suppression of E-box controlled clock genes, including Dbp, and upregulation of Bmal1. However, the absence of TNFR1 does not interfere with the development of SBS and dysregulation of clock genes in mice treated with lipopolysaccharide. Thus, our results suggest that TNFR1 mediates SBS and dysregulation of clock genes in autoimmune diseases.

Recruitment dynamics of the grove-dominant tree Microberlinia bisulcata in African rain forest: extending the light response versus adult longevity trade-off concept

In groves of ectomycorrhizal caesalpiniaceous species in the Atlantic coastal forest of Central Africa the dominant tree Microberlinia bisulcata, which is shade-intolerant as a seedling but highly light-responding as a sapling, shows very limited regeneration. M. bisulcata saplings were mapped in an 82.5-ha plot at Korup and found to be located significantly far (>40 m) away from adults, a result confirmed by direct testing in a second 56-ha plot. Sapling growth over 6 years, the distribution of newly emerging seedlings around adults, recruitment of saplings in a large opening and the outward extent of seedlings at the grove edge were also investigated. Two processes appear to have been operating: (1) a very strong and consistent restriction of the very numerous seedlings establishing after masting close to adults, and (2) a strong but highly spatially variable promotion of distant survivors by increased light from the deaths of large trees of species other than M. bisulcata (which itself has very low mortality rate). This leads to an apparent escape-from-adults effect. To maintain saplings in the shade between multiple short periods of release ectomycorrhizal connections to other co-occurring caesalp species may enable a rachet-type mechanism. The recorded sapling dynamics currently contribute an essential part of the long-term cycling of the groves. M. bisulcata is an interesting example of an important group of tropical trees, particularly in Africa, which are both highly light-demanding when young yet capable also of forming very large forest emergents. To more comprehensively explain tropical tree responses, the case is made for adding a new dimension to the trade-off concept of early tree light-response versus adult longevity.

Do fungal pathogens drive density-dependent mortality in established seedlings of two dominant African rain forest trees?

Where one or a few tree species reach local high abundance, different ecological factors may variously facilitate or hinder their regeneration. Plant pathogens are thought to be one of those possible agents which drive intraspecific density-dependent mortality of tree seedlings in tropical forests. Experimental evidence for this is scarce, however. In an African rain forest at Korup, we manipulated the density of recently established seedlings (~5–8 wk old; low vs. high-density) of two dominant species of contrasting recruitment potential, and altered their exposure to pathogens using a broad-spectrum fungicide. Seedling mortality of the abundantly recruiting subcanopy tree Oubanguia alata was strongly density-dependent after 7 mo, yet fungicide-treated seedlings had slightly higher mortality than controls. By contrast, seedling mortality of the poorly recruiting large canopy-emergent tree Microberlinia bisulcata was unaffected by density or fungicide. Ectomycorrhizal colonization of M. bisulcata was not affected by density or fungicide either. For O. alata, adverse effects of fungicide on its vesicular arbuscular mycorrhizas may have offset any possible benefit of pathogen removal. We tentatively conclude that fungal pathogens are not a likely major cause of density dependence in O. alata, or of early post-establishment mortality in M. bisulcata. They do not explain the latter's currently very low recruitment rate at Korup.

Culture's Calling: Mobile Phones, Gender, and the Making of an African Migrant Village in Lisbon

In this article, I explore how immigrants from the West African nation of Guinea-Bissau living in Portugal use mobile phones in their daily lives in Lisbon. Whereas one might assume that mobile phones and other new information technologies facilitate transnational communication between Africa and Portugal, the ethnographic fieldwork that I conducted in Lisbon from 1999 to 2003 revealed a different scenario. Instead, mobile phones as imagined and used by the Guinean immigrants I met in Lisbon revealed less about transnationalism and globalization than they did about constructing community and identity in a new locale. As Guinean immigrants in Portugal reconfigured their relationship to their former colonizers and struggled to make their way in a new, multicultural Europe, they used their mobile phones to engage local networks, shape local identities, and transform Lisbon's sprawl into an African migrant village. Here, I highlight the gendered dimensions of this process and contend that Guinean men's and women's varied uses of mobile phones in Lisbon underscore contrasting experiences of migration, mobility, and belonging.

Reproducibility of acute mountain sickness in children and adults: a prospective study

Although a history of previous acute mountain sickness (AMS) is commonly used for providing advice and recommending its prophylaxis during subsequent exposure, the intraindividual reproducibility of AMS during repeated high-altitude exposure has never been examined in a prospective controlled study.

Culture's Calling: Mobile Phones, Gender, and the Making of an African Migrant Village in Lisbon

In this article, I explore how immigrants from the West African nation of Guinea-Bissau living in Portugal use mobile phones in their daily lives in Lisbon. Whereas one might assume that mobile phones and other new information technologies facilitate transnational communication between Africa and Portugal, the ethnographic fieldwork that I conducted in Lisbon from 1999 to 2003 revealed a different scenario. Instead, mobile phones as imagined and used by the Guinean immigrants I met in Lisbon revealed less about transnationalism and globalization than they did about constructing community and identity in a new locale. As Guinean immigrants in Portugal reconfigured their relationship to their former colonizers and struggled to make their way in a new, multicultural Europe, they used their mobile phones to engage local networks, shape local identities, and transform Lisbon's sprawl into an African migrant village. Here, I highlight the gendered dimensions of this process and contend that Guinean men's and women's varied uses of mobile phones in Lisbon underscore contrasting experiences of migration, mobility, and belonging.