The global distribution of clinical episodes of Plasmodium falciparum malaria

Interest in mapping the global distribution of malaria is motivated by a need to define populations at risk for appropriate resource allocation and to provide a robust framework for evaluating its global economic impact. Comparison of older and more recent malaria maps shows how the disease has been geographically restricted, but it remains entrenched in poor areas of the world with climates suitable for transmission. Here we provide an empirical approach to estimating the number of clinical events caused by Plasmodium falciparum worldwide, by using a combination of epidemiological, geographical and demographic data. We estimate that there were 515 (range 300-660) million episodes of clinical P. falciparum malaria in 2002. These global estimates are up to 50% higher than those reported by the World Health Organization (WHO) and 200% higher for areas outside Africa, reflecting the WHO's reliance upon passive national reporting for these countries. Without an informed understanding of the cartography of malaria risk, the global extent of clinical disease caused by P. falciparum will continue to be underestimated.     

Human urotensin-II is a potent vasoconstrictor and agonist for the orphan receptor GPR14.

Urotensin-II (U-II) is a vasoactive 'somatostatin-like' cyclic peptide which was originally isolated from fish spinal cords, and which has recently been cloned from man. Here we describe the identification of an orphan human G-protein-coupled receptor homologous to rat GPR14 and expressed predominantly in cardiovascular tissue, which functions as a U-II receptor. Goby and human U-II bind to recombinant human GPR14 with high affinity, and the binding is functionally coupled to calcium mobilization. Human U-II is found within both vascular and cardiac tissue (including coronary atheroma) and effectively constricts isolated arteries from non-human primates. The potency of vasoconstriction of U-II is an order of magnitude greater than that of endothelin-1, making human U-II the most potent mammalian vasoconstrictor identified so far. In vivo, human U-II markedly increases total peripheral resistance in anaesthetized non-human primates, a response associated with profound cardiac contractile dysfunction. Furthermore, as U-II immunoreactivity is also found within central nervous system and endocrine tissues, it may have additional activities.     

Isotopic evidence for dramatic climatic changes in East Africa during the Pleistocene

Rainfall decreased dramatically in the Lake Turkana region 1.8-2.0 Myr ago and in the Olduvai Gorge region 0.5-0.6 Myr ago. This is documented by a major increase in the delta18O values of pedogenic and groundwater carbonates at these times. The data suggest that meteoric water of the earlier, more humid climate was 2-4 per mil lower in 18O content than modern waters of these regions.     

The genetic basis for differences in leaf form between Arabidopsis thaliana and its wild relative Cardamine hirsuta

A key question in biology is how differences in gene function or regulation produce new morphologies during evolution. Here we investigate the genetic basis for differences in leaf form between two closely related plant species, Arabidopsis thaliana and Cardamine hirsuta. We report that in C. hirsuta, class I KNOTTED1-like homeobox (KNOX) proteins are required in the leaf to delay cellular differentiation and produce a dissected leaf form, in contrast to A. thaliana, in which KNOX exclusion from leaves results in a simple leaf form. These differences in KNOX expression arise through changes in the activity of upstream gene regulatory sequences. The function of ASYMMETRIC LEAVES1/ROUGHSHEATH2/PHANTASTICA (ARP) proteins to repress KNOX expression is conserved between the two species, but in C. hirsuta the ARP-KNOX regulatory module controls new developmental processes in the leaf. Thus, evolutionary tinkering with KNOX regulation, constrained by ARP function, may have produced diverse leaf forms by modulating growth and differentiation patterns in developing leaf primordia.     

新方法合成聚芳双硫醚/石墨导电纳米复合材料

利用氧化石墨的氧化性及其在碱性水溶液中剥离分散的性质,将其与芳香二硫酚在碱性水溶液中反应,合成了聚芳双硫醚/石墨导电纳米复合材料.XRD及TEM均证明了无机片层在聚合物基体中呈剥离分散状态.电导率测试表明所合成的纳米复合材料的电导率较氧化石墨提高了近7个数量级.