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The origin of the isotopic signature of Indian mid-ocean ridge basalts has remained enigmatic, because the geochemical composition of these basalts is consistent either with pollution from recycled, ancient altered oceanic crust and sediments, or with ancient continental crust or lithosphere. The radiogenic isotopic signature may therefore be the result of contamination of the upper mantle by plumes containing recycled altered ancient oceanic crust and sediments, detachment and dispersal of continental material into the shallow mantle during rifting and breakup of Gondwana, or contamination of the upper mantle by ancient subduction processes. The identification of a process operating on a scale large enough to affect major portions of the Indian mid-ocean ridge basalt source region has been a long-standing problem. Here we present hafnium and lead isotope data from across the Indian-Pacific mantle boundary at the Australian-Antarctic discordance region of the Southeast Indian Ridge, which demonstrate that the Pacific and Indian upper mantle basalt source domains were each affected by different mechanisms. We infer that the Indian upper-mantle isotope signature in this region is affected mainly by lower continental crust entrained during Gondwana rifting, whereas the isotope signature of the Pacific upper mantle is influenced predominantly by ocean floor subduction-related processes. 相似文献
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Inhibitor of neurite outgrowth in humans 总被引:82,自引:0,他引:82
Prinjha R Moore SE Vinson M Blake S Morrow R Christie G Michalovich D Simmons DL Walsh FS 《Nature》2000,403(6768):383-384
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Kyle Christie 《西北部美国博物学家》2011,69(2)
This study assesses the floristic diversity and affinities of pinyon-juniper (PJ) woodlands in northern Arizona at 2 different scales: regionally within the context of North American floristic patterns and locally within the 2500-m elevation gradient of the San Francisco Volcanic Field (SFVF). An analysis based upon 245 North American floras indicates that the PJ woodlands of the SFVF share strong affinities with the adjacent Colorado Plateau and Apachian floristic elements but also show high floristic similarity to the Great Plains. Data suggest that mid-elevation woodlands of the Colorado Plateau share floristic affinities with the Great Plains that are as strong as or stronger than those shared with the Great Basin. A geostatisical analysis provides a spatially explicit depiction of these findings. A comparison of species occurrences between 6 adjacent biotic communities in northern Arizona reveals that the PJ woodlands host the most distinctive flora among local life zones. Despite what their simple woodland structure may suggest, PJ woodlands of the SFVF host a moderately species-rich flora. This study suggests that the floras of PJ woodlands vary in significant and important ways across the range of PJ woodlands in western North America. 相似文献
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Protein phosphorylation in the pancreatic B-cell 总被引:2,自引:0,他引:2
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Cloning and expression of a rat D2 dopamine receptor cDNA 总被引:24,自引:0,他引:24
J R Bunzow H H Van Tol D K Grandy P Albert J Salon M Christie C A Machida K A Neve O Civelli 《Nature》1988,336(6201):783-787
Dopamine receptors are classified into D1 and D2 subtypes on the basis of their pharmacological and biochemical characteristics. The D2 dopamine receptor has been implicated in the pathophysiology and treatment of movement disorders, schizophrenia and drug addiction. The D2 dopamine receptor interacts with guanine nucleotide-binding proteins to induce second messenger systems. Other members of the family of receptors that are coupled to G proteins share a significant similarity in primary amino-acid sequence and exhibit an archetypical topology predicted to consist of seven putative transmembrane domains. We have taken advantage of the expected nucleotide sequence similarities among members of this gene family to isolate genes coding for new receptors. Using the hamster beta 2-adrenergic receptor gene as a hybridization probe we have isolated related genes including a cDNA encoding the rat D2 dopamine receptor. This receptor has been characterized on the basis of three criteria: the deduced amino-acid sequence which reveals that it is a member of the family of G-protein-coupled receptors; the tissue distribution of the mRNA which parallels that of the D2 dopamine receptor; and the pharmacological profile of mouse fibroblast cells transfected with the cDNA. 相似文献
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G. W. Arbuthnott J. E. Christie T. J. Crow D. Ecclesion D. S. Walter 《Cellular and molecular life sciences : CMLS》1973,29(1):52-53
Résumé Des lésions électrolytiques, soit unilatérales soit bilatérales, ont été pratiquées dans des cerveaux de rats, dans la région du locus coeruleus. Trois semaines après, la teneur en 3-méthoxy-4-hydroxyphénylglycol (MHPG) des deux cortices cérébraux a été analysée par chromatographie à gaz. Les lésions unilatérales ont réduit la teneur en MHPG du cortex ipsilatéral, et après les lésions bilatérales la réduction ent lieu dans les deux cortices. 相似文献
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Muzny DM Scherer SE Kaul R Wang J Yu J Sudbrak R Buhay CJ Chen R Cree A Ding Y Dugan-Rocha S Gill R Gunaratne P Harris RA Hawes AC Hernandez J Hodgson AV Hume J Jackson A Khan ZM Kovar-Smith C Lewis LR Lozado RJ Metzker ML Milosavljevic A Miner GR Morgan MB Nazareth LV Scott G Sodergren E Song XZ Steffen D Wei S Wheeler DA Wright MW Worley KC Yuan Y Zhang Z Adams CQ Ansari-Lari MA Ayele M Brown MJ Chen G Chen Z Clendenning J Clerc-Blankenburg KP Chen R Chen Z Davis C Delgado O Dinh HH Dong W 《Nature》2006,440(7088):1194-1198
After the completion of a draft human genome sequence, the International Human Genome Sequencing Consortium has proceeded to finish and annotate each of the 24 chromosomes comprising the human genome. Here we describe the sequencing and analysis of human chromosome 3, one of the largest human chromosomes. Chromosome 3 comprises just four contigs, one of which currently represents the longest unbroken stretch of finished DNA sequence known so far. The chromosome is remarkable in having the lowest rate of segmental duplication in the genome. It also includes a chemokine receptor gene cluster as well as numerous loci involved in multiple human cancers such as the gene encoding FHIT, which contains the most common constitutive fragile site in the genome, FRA3B. Using genomic sequence from chimpanzee and rhesus macaque, we were able to characterize the breakpoints defining a large pericentric inversion that occurred some time after the split of Homininae from Ponginae, and propose an evolutionary history of the inversion. 相似文献