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281.
M E Andrew V L Braciale T J Henkel J A Hatch T J Braciale 《Journal of immunology (Baltimore, Md. : 1950)》1985,135(5):3520-3523
Influenza-specific immune cytotoxic T lymphocyte (CTL) populations maintain a constant level of in vitro cytolytic activity. This is demonstrable with both heterogeneous populations of anti-viral CTL from immune donors and long-term CTL clones derived from primed CTL precursors. Cytolytic machinery is stably expressed by these CTL populations under a variety of in vitro cultivation conditions. This finding is in contrast to results with alloreactive CTL generated by stimulation of primed CTL precursors that lose cytolytic activity on a per cell basis with time after stimulation. The results indicate that virus-specific, cloned CTL that stably express cytolytic activity are representative of the heterogeneous populations from which they are derived and further suggest a qualitative difference in the regulation and expression of cytolytic machinery between heterogeneous populations of influenza-specific CTL and alloreactive CTL. 相似文献
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The glucosyltransferase (UDP-glucose galactosylhydroxylsine collagen glucosyltransferase, EC 2.4.1.?.) was purified 50-fold from calf arterial tissue by ammonium sulfate precipitation, gel filtration and electrofocusing. The purified enzyme has a molecular weight of 72 000 and a requirement for Mn2. It resolves into two activity peaks when submitted to electrofocusing (isoelectric point at pH 4.2 and 8.1) or disc electrophoresis and exhibits a double pH optimum (pH 8.3 and 9.9). The enzyme was found to transfer glucose from UDP-glucose to the denatured forms of citrate-soluble calf skin collagen (I), the alphal chain (II) and the beta12 component (III) derived from it, and of an acetic-acid-souble collagen preparation (IV) obtained from alkali-treated calf arterial tissue. The Km values for the substrates were 1.67 X 10(-4) (I), 6.3 X 10(-4) (II), 3.3 X 10(-4) (III) and 2.8 X 10(-4) mol/l (IV), indicating that the enzyme has the greatest affinity for the calf skin collagen. The glucose transferred to hydroxylysine-linked galactose residues may be released subsequently by the action of a specific alpha-glucosidase purified from bovine spleen. The results support the assumtion that the glucosylation step in the course of the (pro-)-collagen biosynthesis depends on special structural features of the substrate and may be controlled by a specific alpha-glucosidase. 相似文献
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David A. Aromokeye Oluwatobi E. Oni Jan Tebben Xiuran Yin Tim Richter-Heitmann Jenny Wendt Rolf Nimzyk Sten Littmann Daniela Tienken Ajinkya C. Kulkarni Susann Henkel Kai-Uwe Hinrichs Marcus Elvert Tilmann Harder Sabine Kasten Michael W. Friedrich 《The ISME journal》2021,15(4):965
Elevated dissolved iron concentrations in the methanic zone are typical geochemical signatures of rapidly accumulating marine sediments. These sediments are often characterized by co-burial of iron oxides with recalcitrant aromatic organic matter of terrigenous origin. Thus far, iron oxides are predicted to either impede organic matter degradation, aiding its preservation, or identified to enhance organic carbon oxidation via direct electron transfer. Here, we investigated the effect of various iron oxide phases with differing crystallinity (magnetite, hematite, and lepidocrocite) during microbial degradation of the aromatic model compound benzoate in methanic sediments. In slurry incubations with magnetite or hematite, concurrent iron reduction, and methanogenesis were stimulated during accelerated benzoate degradation with methanogenesis as the dominant electron sink. In contrast, with lepidocrocite, benzoate degradation, and methanogenesis were inhibited. These observations were reproducible in sediment-free enrichments, even after five successive transfers. Genes involved in the complete degradation of benzoate were identified in multiple metagenome assembled genomes. Four previously unknown benzoate degraders of the genera Thermincola (Peptococcaceae, Firmicutes), Dethiobacter (Syntrophomonadaceae, Firmicutes), Deltaproteobacteria bacteria SG8_13 (Desulfosarcinaceae, Deltaproteobacteria), and Melioribacter (Melioribacteraceae, Chlorobi) were identified from the marine sediment-derived enrichments. Scanning electron microscopy (SEM) and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) images showed the ability of microorganisms to colonize and concurrently reduce magnetite likely stimulated by the observed methanogenic benzoate degradation. These findings explain the possible contribution of organoclastic reduction of iron oxides to the elevated dissolved Fe2+ pool typically observed in methanic zones of rapidly accumulating coastal and continental margin sediments.Subject terms: Biogeochemistry, Microbial ecology 相似文献
287.
The whitefly species of the genus Aleurolobus Quaintance and Baker are reviewed from Taiwan. A total of nine species are included. Aleurolobus shiiae Takahashi is new to Taiwan. Aleurolobus osmanthi Young is considered as a junior synonym of Aleurolobus taonabae (Kuwana). A new species, Aleurolobus rubus Dubey and Ko, is described, and the puparia of the new species are diagnosed in a combination of characters: the dorsal pores scattered over dorsum; each located on a large subcircular, chitinised cuticular dorsal marking; faint eye spots; broader submargin; and the vasiform orifice set anterior to the caudal end of puparium by nearly twice of its own length. The record of Aleurolobus philippinensis Quaintance and Baker, and Aleurolobus setigerus Quaintance and Baker from Taiwan is discussed. The puparial diagnosis of each species, identification key to species so far known from Taiwan and illustrations for each species are provided. 相似文献