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971.
Summary Organo-molybdenum microstructures were prepared by visible light irradiation of ammonium molybdate, formaldehyde, ammonium phosphate and a mineral solution. These microstructures are shown to be capable of carbon dioxide photoreduction, nitrogenase activity, and water decomposition, and may represent a metabolic stage between the nonliving and the living.We acknowledge the many discussions and aid of Drs Sherwood Chang, Hyman Hartman, and Messrs Glen Pollock and Andrew Brittain. This work was supported in part by NASA research grant NGR 12-001-109, by the University of Hawaii, and by the NASA Ames Research Center. 相似文献
972.
973.
Summary This study demonstrates polymorphisms in both the length and in the restriction enzyme cleavage sites of honeybee mitochondrial DNA (mtDNA). The levels of variation are typical of those found in other metazoan species. These polymorphisms are potentially useful for the identification of Africanized bees in the western hemisphere and for study of honeybee phylogenetics. 相似文献
974.
Summary The effects of adding LiCl, RbCl, KCl or NaCl to sea water at concentrations up to 30 mmoles/1 on the frequency of contraction of jellyfish (Aurelia aurita) suggest that studies on phylogenetically low animals with relatively simple nervous systems may be of use to determine mechanisms of action of lithium and rubidium on movements.Acknowledgments. We thank P. Carl Petersens Fund and the Danish Medical Research Council for financial support and Henning Petersen for permission to carry out our experiments at Mols Laboratory. 相似文献
975.
Sex chromosome abnormalities 总被引:2,自引:0,他引:2
976.
977.
978.
M J Smith 《Experientia》1989,45(5):452-457
This article reviews several new developments in vanadium biochemistry, as elucidated from studies of ascidians. A hypothesis correlating ascidian blood cell function to anaerobiosis, via two prominent redox constituents, namely vanadium(III) and the tunichromes, a family of metal ion complexing/reducing hydroquinonoid peptides, is presented. 相似文献
979.
Stimulation of bone resorption and inhibition of bone formation in vitro by human tumour necrosis factors 总被引:75,自引:0,他引:75
When leukocytes are exposed to mitogens or antigens in vitro, they release bone-resorbing activity into the culture supernatants which can be detected by bioassay. Like many lymphocyte-monocyte products, this activity has been difficult to purify because of its low abundance in activated leukocyte cultures and the unwieldy bioassay required to detect biological activity. Partially purified preparations of this activity inhibit bone collagen synthesis in organ cultures of fetal rat calvariae. Recent data suggest that both activated lymphocytes and monocytes release factors which could contribute to this activity. Recently, monocyte-derived tumour necrosis factor alpha (TNF-alpha) and lymphocyte-derived tumour necrosis factor beta (TNF-beta) (previously called lymphotoxin), two multifunctional cytokines which have similar cytotoxic effects on neoplastic cell lines, have been purified to homogeneity and their complementary DNAs cloned and expressed in Escherichia coli. As both of these cytokines are likely to be present in activated leukocyte supernatants, we tested purified recombinant preparations for their effects on bone resorption and bone collagen synthesis in vitro, and report here that both cytokines at 10(-7) to 10(-9) M caused osteoclastic bone resorption and inhibited bone collagen synthesis. These data suggest that at least part of the bone-resorbing activity present in activated leukocyte culture supernatants may be due to these cytokines. 相似文献
980.