The viking biological investigation: preliminary results     

Klein HP  Horowitz NH  Levin GV  Oyama VI  Lederberg J  Rich A  Hubbard JS  Hobby GL  Straat PA  Berdahl BJ  Carle GC  Brown FS  Johnson RD 《Science (New York, N.Y.)》1976,194(4260):99-105

Three different types of biological experiments on samples of martian surface material ("soil") were conducted inside the Viking lander. In the carbon assimilation or pyrolytic release experiment, (14)CO(2) and (14)CO were exposed to soil in the presence of light. A small amount of gas was found to be converted into organic material. Heat treatment of a duplicate sample prevented such conversion. In the gas exchange experiment, soil was first humidified (exposed to water vapor) for 6 sols and then wet with a complex aqueous solution of metabolites. The gas above the soil was monitored by gas chromatography. A substantial amount of O(2) was detected in the first chromatogram taken 2.8 hours after humidification. Subsequent analyses revealed that significant increases in CO(2) and only small changes in N(2) had also occurred. In the labeled release experiment, soil was moistened with a solution containing several (14)C-labeled organic compounds. A substantial evolution of radioactive gas was registered but did not occur with a duplicate heat-treated sample. Alternative chemical and biological interpretations are possible for these preliminary data. The experiments are still in process, and these results so far do not allow a decision regarding the existence of life on the plonet Mars.  相似文献   

Hemoxygenase-2 is an oxygen sensor for a calcium-sensitive potassium channel     

Williams SE  Wootton P  Mason HS  Bould J  Iles DE  Riccardi D  Peers C  Kemp PJ 《Science (New York, N.Y.)》2004,306(5704):2093-2097

Modulation of calcium-sensitive potassium (BK) channels by oxygen is important in several mammalian tissues, and in the carotid body it is crucial to respiratory control. However, the identity of the oxygen sensor remains unknown. We demonstrate that hemoxygenase-2 (HO-2) is part of the BK channel complex and enhances channel activity in normoxia. Knockdown of HO-2 expression reduced channel activity, and carbon monoxide, a product of HO-2 activity, rescued this loss of function. Inhibition of BK channels by hypoxia was dependent on HO-2 expression and was augmented by HO-2 stimulation. Furthermore, carotid body cells demonstrated HO-2-dependent hypoxic BK channel inhibition, which indicates that HO-2 is an oxygen sensor that controls channel activity during oxygen deprivation.  相似文献   

Genetic and immunological complexity of major histocompatibility regions   总被引：24，自引：0，他引：24  

F H Bach  M B Widmer  M Segall  M L Bach  J Klein 《Science (New York, N.Y.)》1972,176(38):1024-1027

There are genetic differences within the major histocompatibility complex of the mouse which lead to skin graft rejection but which cannot be detected serologically. When confronted with these differences on allogeneic cells, lymphocytes proliferate in vitro. In other cases, in vitro lymphocyte proliferation but no skin graft rejection is associated with loci that are linked to but genetically separable from the loci controlling the serologically defined antigens.  相似文献   

Griseofulvin: a teratogenic study   总被引：4，自引：0，他引：4  

M F Klein  J R Beall 《Science (New York, N.Y.)》1972,175(29):1483-1484

Griseofulvin, a fungistatic agent, was administered in oral doses of 125 to 1500 milligrams per kilogramn per day to pregnant rats during organogenesis. Evaluation of the offspring from dams treated with the largest doses, 63 and 75 times a therapeutic dose in man, indicated decreased survival rates and a syndrome of malformations.  相似文献   

Adenosine 3',5'-monophosphate-dependent protein kinase of cultured mammalian cells   总被引：3，自引：0，他引：3  

M I Klein  M H Makman 《Science (New York, N.Y.)》1971,172(985):863-864

Protein kinase was partially purified from Chang's liver cells, 3T6 mouse embryo fibroblasts, and HeLa cells. The rate of histone phosphorylation catalyzed by the kinase from each of these cell lines was stimulated two- to three-fold by 1 x 10(-6) molar adenosine 3',5'-monophosphate. The same concentration of guanosine 3',5'-monophosphate failed to stimulate these kinases.  相似文献   

Nuclear collective motion     

Klein A 《Science (New York, N.Y.)》1980,207(4429):398

  相似文献   

Literature program of engineering societies     

Klein S 《Science (New York, N.Y.)》1967,155(3770):1698-1699

  相似文献   

Impaired prion replication in spleens of mice lacking functional follicular dendritic cells     

Montrasio F  Frigg R  Glatzel M  Klein MA  Mackay F  Aguzzi A  Weissmann C 《Science (New York, N.Y.)》2000,288(5469):1257-1259

In scrapie-infected mice, prions are found associated with splenic but not circulating B and T lymphocytes and in the stroma, which contains follicular dendritic cells (FDCs). Formation and maintenance of mature FDCs require the presence of B cells expressing membrane-bound lymphotoxin-alpha/beta. Treatment of mice with soluble lymphotoxin-beta receptor results in the disappearance of mature FDCs from the spleen. We show that this treatment abolishes splenic prion accumulation and retards neuroinvasion after intraperitoneal scrapie inoculation. These data provide evidence that FDCs are the principal sites for prion replication in the spleen.  相似文献   

Mitotic Golgi partitioning is driven by the membrane-fissioning protein CtBP3/BARS     

Hidalgo Carcedo C  Bonazzi M  Spanò S  Turacchio G  Colanzi A  Luini A  Corda D 《Science (New York, N.Y.)》2004,305(5680):93-96

Organelle inheritance is an essential feature of all eukaryotic cells. As with other organelles, the Golgi complex partitions between daughter cells through the fission of its membranes into numerous tubulovesicular fragments. We found that the protein CtBP3/BARS (BARS) was responsible for driving the fission of Golgi membranes during mitosis in vivo. Moreover, by in vitro analysis, we identified two stages of this Golgi fragmentation process: disassembly of the Golgi stacks into a tubular network, and BARS-dependent fission of these tubules. Finally, this BARS-induced fission of Golgi membranes controlled the G2-to-prophase transition of the cell cycle, and hence cell division.  相似文献   

Regulation of bone mass in mice by the lipoxygenase gene Alox15     

Klein RF  Allard J  Avnur Z  Nikolcheva T  Rotstein D  Carlos AS  Shea M  Waters RV  Belknap JK  Peltz G  Orwoll ES 《Science (New York, N.Y.)》2004,303(5655):229-232

The development of osteoporosis involves the interaction of multiple environmental and genetic factors. Through combined genetic and genomic approaches, we identified the lipoxygenase gene Alox15 as a negative regulator of peak bone mineral density in mice. Crossbreeding experiments with Alox15 knockout mice confirmed that 12/15-lipoxygenase plays a role in skeletal development. Pharmacologic inhibitors of this enzyme improved bone density and strength in two rodent models of osteoporosis. These results suggest that drugs targeting the 12/15-lipoxygenase pathway merit investigation as a therapy for osteoporosis.  相似文献