Positional identification of TNFSF4, encoding OX40 ligand, as a gene that influences atherosclerosis susceptibility

Ath1 is a quantitative trait locus on mouse chromosome 1 that renders C57BL/6 mice susceptible and C3H/He mice resistant to diet-induced atherosclerosis. The quantitative trait locus region encompasses 11 known genes, including Tnfsf4 (also called Ox40l or Cd134l), which encodes OX40 ligand. Here we report that mice with targeted mutations of Tnfsf4 had significantly (P 相似文献   

Indication of drier periods on Mars from the chemistry and mineralogy of atmospheric dust

The ubiquitous atmospheric dust on Mars is well mixed by periodic global dust storms, and such dust carries information about the environment in which it once formed and hence about the history of water on Mars. The Mars Exploration Rovers have permanent magnets to collect atmospheric dust for investigation by instruments on the rovers. Here we report results from M?ssbauer spectroscopy and X-ray fluorescence of dust particles captured from the martian atmosphere by the magnets. The dust on the magnets contains magnetite and olivine; this indicates a basaltic origin of the dust and shows that magnetite, not maghemite, is the mineral mainly responsible for the magnetic properties of the dust. Furthermore, the dust on the magnets contains some ferric oxides, probably including nanocrystalline phases, so some alteration or oxidation of the basaltic dust seems to have occurred. The presence of olivine indicates that liquid water did not play a dominant role in the processes that formed the atmospheric dust.     

Infection of cultured intestinal epithelial cells with severe acute respiratory syndrome coronavirus

To identify a model for the study of intestinal pathogenesis of severe acute respiratory syndrome (SARS) we tested the sensitivity of six human intestinal epithelial cell lines to infection with SARS coronavirus (SARS-CoV). In permissive cell lines, effects of SARS-CoV on cellular gene expression were analysed using high-density oligonucleotide arrays. Caco-2 and CL-14 cell lines were found to be highly permissive to SARS-CoV, due to the presence of angiotensin-converting enzyme 2 as a functional receptor. In both cell lines, SARS-CoV infection deregulated expression of cellular genes which may be important for the intestinal pathogenesis of SARS.Received 23 May 2004; received after revision 23 June 2004; accepted 25 June 2004     

Catalytic enantioselective reactions driven by photoinduced electron transfer

Photoinduced electron transfer is an essential step in the conversion of solar energy into chemical energy in photosystems I and II (ref. 1), and is also frequently used by chemists to build complex molecules from simple precursors. During this process, light absorption generates molecules in excited electronic states that are susceptible to accepting or donating electrons. But although the excited states are straightforward to generate, their short lifetimes makes it challenging to control electron transfer and subsequent product formation-particularly if enantiopure products are desired. Control strategies developed so far use hydrogen bonding, to embed photochemical substrates in chiral environments and to render photochemical reactions enantioselective through the use of rigid chiral complexing agents. To go beyond such stoichiometric chiral information transmission, catalytic turnover is required. Here we present a catalytic photoinduced electron transfer reaction that proceeds with considerable turnover and high enantioselectivity. By using an electron accepting chiral organocatalyst that enforces a chiral environment on the substrate through hydrogen bonding, we obtain the product in significant enantiomeric excess (up to 70%) and in yields reaching 64%. This performance suggests that photochemical routes to chiral compounds may find use in general asymmetric synthesis.     

Somatic mutations in PTPN11 in juvenile myelomonocytic leukemia,myelodysplastic syndromes and acute myeloid leukemia

We report here that individuals with Noonan syndrome and juvenile myelomonocytic leukemia (JMML) have germline mutations in PTPN11 and that somatic mutations in PTPN11 account for 34% of non-syndromic JMML. Furthermore, we found mutations in PTPN11 in a small percentage of individuals with myelodysplastic syndrome (MDS) and de novo acute myeloid leukemia (AML). Functional analyses documented that the two most common mutations in PTPN11 associated with JMML caused a gain of function.     

Riverine export of aged terrestrial organic matter to the North Atlantic Ocean

Global riverine discharge of organic matter represents a substantial source of terrestrial dissolved and particulate organic carbon to the oceans. This input from rivers is, by itself, more than large enough to account for the apparent steady-state replacement times of 4,00-6,000 yr for oceanic dissolved organic carbon. But paradoxically, terrestrial organic matter, derived from land plants, is not detected in seawater and sediments in quantities that correspond to its inputs. Here we present natural 14C and 13C data from four rivers that discharge to the western North Atlantic Ocean and find that these rivers are sources of old (14C-depleted) and young (14C-enriched) terrestrial dissolved organic carbon, and of predominantly old terrestrial particulate organic carbon. These findings contrast with limited earlier data that suggested terrestrial organic matter transported by rivers might be generally enriched in 14C from nuclear testing, and hence newly produced. We also find that much of the young dissolved organic carbon can be selectively degraded over the residence times of river and coastal waters, leaving an even older and more refractory component for oceanic export. Thus, pre-ageing and degradation may alter significantly the structure, distributions and quantities of terrestrial organic matter before its delivery to the oceans.     

Papaverine blockade of the calcium action in depolarized taenia coli of the guinea-pig

Zusammenfassung Es wird die muskellähmende Wirkung von Papaverin auf die depolarisierte Taenia coli durch die Blockade des Kalziumionenstromes durch die Zellmembran erklärt.     

Modification and use of plastic embedding forms in electron microscopy

Zusammenfassung Einbettungsformen aus Silikongummi wurden entwickelt mit dem Ziel, eine einfache, saubere und rasche Einbettung für eine grosse Zahl von Gewebsblöcken zu erreichen. Die Formen sind für Epon, Epon-Araldit und Maraglas, aber nicht für Vestopal verwendbar.