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1.
Angiotensin-converting enzyme 2 is an essential regulator of heart function   总被引:131,自引:0,他引:131  
Cardiovascular diseases are predicted to be the most common cause of death worldwide by 2020. Here we show that angiotensin-converting enzyme 2 (ace2) maps to a defined quantitative trait locus (QTL) on the X chromosome in three different rat models of hypertension. In all hypertensive rat strains, ACE2 messenger RNA and protein expression were markedly reduced, suggesting that ace2 is a candidate gene for this QTL. Targeted disruption of ACE2 in mice results in a severe cardiac contractility defect, increased angiotensin II levels, and upregulation of hypoxia-induced genes in the heart. Genetic ablation of ACE on an ACE2 mutant background completely rescues the cardiac phenotype. But disruption of ACER, a Drosophila ACE2 homologue, results in a severe defect of heart morphogenesis. These genetic data for ACE2 show that it is an essential regulator of heart function in vivo.  相似文献   
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It is important that migration is measured accurately, for example to inform population estimates and projections. However, current sources of information make it difficult to produce robust estimates of emigration from Great Britain. Several other countries, including Ireland, make use of household surveys in their estimates of migration. To investigate the feasibility of obtaining information on emigration from those resident in Great Britain, three questions were included in the Omnibus Survey for two months. Respondents were asked whether they had plans to emigrate or whether anyone in their family had recently emigrated or intended to shortly. This article reports on the results of this pilot, providing evidence on response levels, comparison with the International Passenger Survey and feedback from interviewers on the questions asked.  相似文献   
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The ONS produces mid-year population estimates annually, which are based on updating from the most recent census. Therefore, whenever results become available from a census, a new base is created for the population estimates. This has implications for historic series, which need to be revised to be consistent with both the past and the most recent census. This article describes the methodology that will be used for this rebasing of the mid-year population estimates following the availability of results from the 2001 Census. Census results also provide a unique opportunity to assess the accuracy of the population estimates that are based on the previous census and this article also describes the approach that will be taken to the assessment of accuracy.  相似文献   
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A 40,000 year-old human occupation site at Huon Peninsula, Papua New Guinea   总被引:5,自引:0,他引:5  
L Groube  J Chappell  J Muke  D Price 《Nature》1986,324(6096):453-455
The geographical position of the island of New Guinea suggests that it may have been an early staging post in the Pleistocene settlement of Australia from the Indonesia-Indochina region. Previous data have not supported this, as archaeological sites 35,000 to 40,000 years old occur in southern Australia, whereas the earliest previously known in Papua New Guinea is 26,000 years old. We now report evidence that the north coast of Papua New Guinea was occupied at least 40,000 years ago. Sahuland, which is the greater land area of Australia and New Guinea plus their connecting continental shelf exposed as land when Pleistocene sea levels were lower than now, was occupied by humans in several widely separated areas at that time. A distinctive 'waisted axe' culture appears to have existed in New Guinea and probably in Australia in the Late Pleistocene, but antecedents are not yet known from east and southeast Asia. There is evidence for hafting of these tools at a date which is earlier than known elsewhere in the world.  相似文献   
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The factors that control the growth and nitrogen fixation rates of marine diazotrophs such as Trichodesmium have been intensively studied because of the role that these processes have in the global cycling of carbon and nitrogen, and in the sequestration of carbon to the deep sea. Because the phosphate concentrations of many ocean gyres are low, the bioavailability of the larger, chemically heterogeneous pool of dissolved organic phosphorus could markedly influence Trichodesmium physiology. Here we describe the induction, by phosphorus stress, of genes from the Trichodesmium erythraeum IMS101 genome that are predicted to encode proteins associated with the high-affinity transport and hydrolysis of phosphonate compounds by a carbon-phosphorus lyase pathway. We show the importance of these genes through expression analyses with T. erythraeum from the Sargasso Sea. Phosphonates are known to be present in oligotrophic marine systems, but have not previously been considered to be bioavailable to marine diazotrophs. The apparent absence of genes encoding a carbon-phosphorus lyase pathway in the other marine cyanobacterial genomes suggests that, relative to other phytoplankton, Trichodesmium is uniquely adapted for scavenging phosphorus from organic sources. This adaptation may help to explain the prevalence of Trichodesmium in low phosphate, oligotrophic systems.  相似文献   
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When continents break apart, the rifting is sometimes accompanied by the production of large volumes of molten rock. The total melt volume, however, is uncertain, because only part of it has erupted at the surface. Furthermore, the cause of the magmatism is still disputed-specifically, whether or not it is due to increased mantle temperatures. We recorded deep-penetration normal-incidence and wide-angle seismic profiles across the Faroe and Hatton Bank volcanic margins in the northeast Atlantic. Here we show that near the Faroe Islands, for every 1 km along strike, 360-400 km(3) of basalt is extruded, while 540-600 km(3) is intruded into the continent-ocean transition. We find that lower-crustal intrusions are focused mainly into a narrow zone approximately 50 km wide on the transition, although extruded basalts flow more than 100 km from the rift. Seismic profiles show that the melt is intruded into the lower crust as sills, which cross-cut the continental fabric, rather than as an 'underplate' of 100 per cent melt, as has often been assumed. Evidence from the measured seismic velocities and from igneous thicknesses are consistent with the dominant control on melt production being increased mantle temperatures, with no requirement for either significant active small-scale mantle convection under the rift or the presence of fertile mantle at the time of continental break-up, as has previously been suggested for the North Atlantic Ocean.  相似文献   
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What’s new in the renin-angiotensin system?   总被引:6,自引:0,他引:6  
Virtually all existing evidence on the function of angiotensin II (Ang II) in the regulation of tissue homeostasis and blood pressure regulation bears on the more restricted question of what other mechanisms or systems may amplify or inhibit the actions of this important peptide. Whereas there is evidence that Ang II may potentiate the effects of catecholamines, various cytokines and also growth factors, the repertoire of substances which may inhibit the actions of Ang II is more limited and has been restricted primarily to prostacyclin, bradykinin and nitric oxide. Advances in receptor pharmacology and introduction of selective antagonists to two of the receptor subtypes at which Ang II binds permitted a more critical examination of the functions of the renin angiotensin system in physiological and pathophysiological conditions, as well as uncovering the previously unsuspected possibility that within the biochemical pathways leading to the formation of the peptide the renin angiotensin system could process either its immediate precursor (angiotensin I) or the actual Ang II peptide into an alternative form, angiotensin-(1-7) [Ang-(1-7)], the function of which was to antagonize the effects of Ang II. We review here the biological actions of Ang-(1-7) and discuss how this discovery may change altogether the perception of how the renin angiotensin system functions in the regulation of tissue perfusion pressure and the regulation of salt and water metabolism.  相似文献   
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宇宙成因核素10Be,26Al:原理及其在地表过程中的应用   总被引:1,自引:0,他引:1  
地表岩石中宇宙成因核素10Be和26Al含量是侵蚀速率和辐射时间的函数,通过对岩石中10Be和26Al含量的测定能反映较长时间(103~107a)和较大空间尺度上的侵蚀作用大小和过程.根据10Be含量估算出长江中下游地区平均侵蚀速率为30~60m·Ma-1,攀枝花至三峡长江流域内地表平均侵蚀速率为200m·Ma-1.  相似文献   
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