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241.
Elachi C Wall S Janssen M Stofan E Lopes R Kirk R Lorenz R Lunine J Paganelli F Soderblom L Wood C Wye L Zebker H Anderson Y Ostro S Allison M Boehmer R Callahan P Encrenaz P Flamini E Francescetti G Gim Y Hamilton G Hensley S Johnson W Kelleher K Muhleman D Picardi G Posa F Roth L Seu R Shaffer S Stiles B Vetrella S West R 《Nature》2006,441(7094):709-713
Cassini's Titan Radar Mapper imaged the surface of Saturn's moon Titan on its February 2005 fly-by (denoted T3), collecting high-resolution synthetic-aperture radar and larger-scale radiometry and scatterometry data. These data provide the first definitive identification of impact craters on the surface of Titan, networks of fluvial channels and surficial dark streaks that may be longitudinal dunes. Here we describe this great diversity of landforms. We conclude that much of the surface thus far imaged by radar of the haze-shrouded Titan is very young, with persistent geologic activity. 相似文献
242.
Gregory SG Barlow KF McLay KE Kaul R Swarbreck D Dunham A Scott CE Howe KL Woodfine K Spencer CC Jones MC Gillson C Searle S Zhou Y Kokocinski F McDonald L Evans R Phillips K Atkinson A Cooper R Jones C Hall RE Andrews TD Lloyd C Ainscough R Almeida JP Ambrose KD Anderson F Andrew RW Ashwell RI Aubin K Babbage AK Bagguley CL Bailey J Beasley H Bethel G Bird CP Bray-Allen S Brown JY Brown AJ Buckley D Burton J Bye J Carder C Chapman JC Clark SY Clarke G Clee C Cobley V Collier RE Corby N 《Nature》2006,441(7091):315-321
The reference sequence for each human chromosome provides the framework for understanding genome function, variation and evolution. Here we report the finished sequence and biological annotation of human chromosome 1. Chromosome 1 is gene-dense, with 3,141 genes and 991 pseudogenes, and many coding sequences overlap. Rearrangements and mutations of chromosome 1 are prevalent in cancer and many other diseases. Patterns of sequence variation reveal signals of recent selection in specific genes that may contribute to human fitness, and also in regions where no function is evident. Fine-scale recombination occurs in hotspots of varying intensity along the sequence, and is enriched near genes. These and other studies of human biology and disease encoded within chromosome 1 are made possible with the highly accurate annotated sequence, as part of the completed set of chromosome sequences that comprise the reference human genome. 相似文献
243.
The thymus provides an essential environment for the development of T cells from haemopoietic progenitors. This environment is separated into cortical and medullary regions, each containing functionally distinct epithelial populations that are important at successive stages of T-cell development and selection. However, the developmental origin and lineage relationships between cortical and medullary epithelial cell types remain controversial. Here we describe a clonal assay to investigate the developmental potential of single, individually selected, thymic epithelial progenitors (marked with enhanced yellow fluorescent protein) developing within the normal architecture of the thymus. Using this approach, we show that cortical and medullary epithelial cells share a common origin in bipotent precursors, providing definitive evidence that they have a single rather than dual germ layer origin during embryogenesis. Our findings resolve a long-standing issue in thymus development, and are important in relation to the development of cell-based strategies for thymus disorders and the possibility of restoring function of the atrophied adult thymus. 相似文献
244.
NM Archin AL Liberty AD Kashuba SK Choudhary JD Kuruc AM Crooks DC Parker EM Anderson MF Kearney MC Strain DD Richman MG Hudgens RJ Bosch JM Coffin JJ Eron DJ Hazuda DM Margolis 《Nature》2012,487(7408):482-485
Despite antiretroviral therapy, proviral latency of human immunodeficiency virus type 1 (HIV-1) remains a principal obstacle to curing the infection. Inducing the expression of latent genomes within resting CD4(+) T cells is the primary strategy to clear this reservoir. Although histone deacetylase inhibitors such as suberoylanilide hydroxamic acid (also known as vorinostat, VOR) can disrupt HIV-1 latency in vitro, the utility of this approach has never been directly proven in a translational clinical study of HIV-infected patients. Here we isolated the circulating resting CD4(+) T cells of patients in whom viraemia was fully suppressed by antiretroviral therapy, and directly studied the effect of VOR on this latent reservoir. In each of eight patients, a single dose of VOR increased both biomarkers of cellular acetylation, and simultaneously induced an increase in HIV RNA expression in resting CD4(+) cells (mean increase, 4.8-fold). This demonstrates that a molecular mechanism known to enforce HIV latency can be therapeutically targeted in humans, provides proof-of-concept for histone deacetylase inhibitors as a therapeutic class, and defines a precise approach to test novel strategies to attack and eradicate latent HIV infection directly. 相似文献
245.
Jex AR Liu S Li B Young ND Hall RS Li Y Yang L Zeng N Xu X Xiong Z Chen F Wu X Zhang G Fang X Kang Y Anderson GA Harris TW Campbell BE Vlaminck J Wang T Cantacessi C Schwarz EM Ranganathan S Geldhof P Nejsum P Sternberg PW Yang H Wang J Wang J Gasser RB 《Nature》2011,479(7374):529-533
Parasitic diseases have a devastating, long-term impact on human health, welfare and food production worldwide. More than two billion people are infected with geohelminths, including the roundworms Ascaris (common roundworm), Necator and Ancylostoma (hookworms), and Trichuris (whipworm), mainly in developing or impoverished nations of Asia, Africa and Latin America. In humans, the diseases caused by these parasites result in about 135,000 deaths annually, with a global burden comparable with that of malaria or tuberculosis in disability-adjusted life years. Ascaris alone infects around 1.2 billion people and, in children, causes nutritional deficiency, impaired physical and cognitive development and, in severe cases, death. Ascaris also causes major production losses in pigs owing to reduced growth, failure to thrive and mortality. The Ascaris-swine model makes it possible to study the parasite, its relationship with the host, and ascariasis at the molecular level. To enable such molecular studies, we report the 273 megabase draft genome of Ascaris suum and compare it with other nematode genomes. This genome has low repeat content (4.4%) and encodes about 18,500 protein-coding genes. Notably, the A. suum secretome (about 750 molecules) is rich in peptidases linked to the penetration and degradation of host tissues, and an assemblage of molecules likely to modulate or evade host immune responses. This genome provides a comprehensive resource to the scientific community and underpins the development of new and urgently needed interventions (drugs, vaccines and diagnostic tests) against ascariasis and other nematodiases. 相似文献
246.
247.
The spread of HIV-1 in Africa: sexual contact patterns and the predicted demographic impact of AIDS 总被引:11,自引:0,他引:11
The spread of HIV-1 in Africa is examined here in the light of recent information on the main epidemiological and behavioural determinants of transmission. Mathematical models incorporating demographic, epidemiological and behavioural processes are used to assess the potential demographic impact of the disease AIDS. These analyses highlight the significance of patterns of sexual behaviour, and in particular networks of sexual contact, on the predicted spread of infection. Current data reveal substantial variations in the degree of spread between and in countries, but new analyses support earlier predictions that in the worst-afflicted areas AIDS is likely to change population growth rates from positive to negative values in a few decades. 相似文献
248.
C Anderson 《Nature》1992,360(6403):399-400
249.
Transmission dynamics of HIV infection 总被引:12,自引:0,他引:12
Simple mathematical models of the transmission dynamics of human immunodeficiency virus help to clarify some of the essential relations between epidemiological factors, such as distributed incubation periods and heterogeneity in sexual activity, and the overall pattern of the AIDS epidemic. They also help to identify what kinds of epidemiological data are needed to make predictions of future trends. 相似文献
250.
Studies of host resistance to parasite infection are usually based on experimental designs involving a primary infection and subsequent challenge exposure, resistance being recorded as the percentage reduction in parasite establishment in challenged hosts when compared with that in uninfected animals. Few studies have focused on the dynamic nature of helminth establishment and mortality (and their presumed dependency on the rate of current exposure and past experiences of infection) in hosts repeatedly exposed to low levels of infection. Here, we report the results of population studies on the dynamics of resistance to Schistosoma mansoni infection (a helminth parasite) in mice repeatedly exposed to cercarial invasion. Parasite burdens created by different levels and durations of exposure to infection reflect a dynamic interplay between rates of helminth establishment and mortality. Depending on the intensity of exposure, changes in worm load with duration of host infection vary from monotonic growth to a stable average parasite burden to convex curves in which the average load attains a maximum value before decaying in old animals. These trends are similar to observed patterns of S. mansoni infection in human communities. 相似文献