Defect in vitamin B12 release from lysosomes: newly described inborn error of vitamin B12 metabolism   总被引：5，自引：0，他引：5  

D S Rosenblatt  A Hosack  N V Matiaszuk  B A Cooper  R Laframboise 《Science (New York, N.Y.)》1985,228(4705):1319-1321

Cultured diploid fibroblasts from a patient with a previously undescribed inborn error of cobalamin metabolism accumulate unmetabolized, nonprotein-bound vitamin B12 in lysosomes. These cells are able to endocytose the transcobalamin II-B12 complex and to release B12 from transcobalamin II. The freed vitamin B12 is not released from lysosomes into the cytoplasm of the cell. This suggests that there is a specific lysosomal transport mechanism for vitamin B12 in the human.  相似文献   

The cost of R & d living     

Berger M  Cooper MJ 《Science (New York, N.Y.)》1979,204(4400):1369

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Climate. Society and sea level rise     

Pilkey OH  Cooper JA 《Science (New York, N.Y.)》2004,303(5665):1781-1782

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Isoprenoid acids in recent sediments     

Blumer M  Cooper WJ 《Science (New York, N.Y.)》1967,158(3807):1463-1464

Phytanic acid, pristanic acid, and 4,8,12-trimethyltridecanoic acid have been isolated from three recent marine sediments. The ratio of palmitic to pristanic acid is similar to that encountered in typical marine lipids. This suggests a biochemical origin of these sedimentary acids; phytol is their presumed biochemical precursor. Other isoprenoid acids between C(11) and C(22) which are common in ancient sediments have not been found. They are probably geochemical products formed slowly and at a greater depth.  相似文献   

Genetic effects of captive breeding cause a rapid, cumulative fitness decline in the wild     

Araki H  Cooper B  Blouin MS 《Science (New York, N.Y.)》2007,318(5847):100-103

Captive breeding is used to supplement populations of many species that are declining in the wild. The suitability of and long-term species survival from such programs remain largely untested, however. We measured lifetime reproductive success of the first two generations of steelhead trout that were reared in captivity and bred in the wild after they were released. By reconstructing a three-generation pedigree with microsatellite markers, we show that genetic effects of domestication reduce subsequent reproductive capabilities by approximately 40% per captive-reared generation when fish are moved to natural environments. These results suggest that even a few generations of domestication may have negative effects on natural reproduction in the wild and that the repeated use of captive-reared parents to supplement wild populations should be carefully reconsidered.  相似文献   

ACDA Staffing     

Cooper HF 《Science (New York, N.Y.)》1983,220(4592):6

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Rise and fall of species occupancy in Cenozoic fossil mollusks     

Foote M  Crampton JS  Beu AG  Marshall BA  Cooper RA  Maxwell PA  Matcham I 《Science (New York, N.Y.)》2007,318(5853):1131-1134

In the time between speciation and extinction, a species' ecological and biogeographic footprint-its occupancy-will vary in response to macroecological drivers and historical contingencies. Despite their importance for understanding macroecological processes, general patterns of long-term species occupancy remain largely unknown. We documented the occupancy histories of Cenozoic marine mollusks from New Zealand. For both genera and species, these show a distinct pattern of increase to relatively short-lived peak occupancy at mid-duration, followed by a decline toward extinction. Thus, species at greatest risk for extinction are those that have already been in decline for a substantial period of time. This pattern of protracted rise and fall stands in contrast to that of incumbency, insofar as species show no general tendency to stay near maximal occupancy once established.  相似文献   

Medulloblastoma growth inhibition by hedgehog pathway blockade     

Berman DM  Karhadkar SS  Hallahan AR  Pritchard JI  Eberhart CG  Watkins DN  Chen JK  Cooper MK  Taipale J  Olson JM  Beachy PA 《Science (New York, N.Y.)》2002,297(5586):1559-1561

Constitutive Hedgehog (Hh) pathway activity is associated with initiation of neoplasia, but its role in the continued growth of established tumors is unclear. Here, we investigate the therapeutic efficacy of the Hh pathway antagonist cyclopamine in preclinical models of medulloblastoma, the most common malignant brain tumor in children. Cyclopamine treatment of murine medulloblastoma cells blocked proliferation in vitro and induced changes in gene expression consistent with initiation of neuronal differentiation and loss of neuronal stem cell-like character. This compound also caused regression of murine tumor allografts in vivo and induced rapid death of cells from freshly resected human medulloblastomas, but not from other brain tumors, thus establishing a specific role for Hh pathway activity in medulloblastoma growth.  相似文献   

Thiamine release from nerve membranes by tetrodotoxin   总被引：3，自引：0，他引：3  

Y Itokawa  J R Cooper 《Science (New York, N.Y.)》1969,166(906):759-761

Tetrodotoxin (3 x 10(-8) molar) promoted the release of thiamine from perfused rat and frog nerve preparations in a manner similar to other neuroactive drugs. When the rats were injected with thiamine labeled with sulfur-35, analyses of brain, spinal cord, and sciatic nerve homogenates revealed labeled thiamine in membrane, synaptosomes, and mitochondrial subfractions. However, on incubation of these fractions with tetrodotoxin, thiamine was released only from the membrane fragments.  相似文献   

Molecular defect in a gamma-2 heavy chain   总被引：9，自引：0，他引：9  

S M Cooper  E C Franklin  B Frangione 《Science (New York, N.Y.)》1972,176(31):187-189

The first gamma-2 (gamma2) heavy chain disease protein Gif has pyrroli-dinecarboxylic acid as its amino terminal residue, much of the Fd variable region, and an internal deletion of the heavy chain of about 100 residues corresponding to most of the Fd constant region. Normal sequence resumes with a glutamic acid residue at position 216 in the hinge region. This is the third gamma heavy chain disease protein where normal sequence resumes at the same position after the deletion.  相似文献