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Oxidation of Ferrous Iron and Elemental Sulfur by Thiobacillus ferrooxidans 总被引:2,自引:1,他引:1 下载免费PDF全文
Romilio T. Espejo Blanca Escobar Eugenia Jedlicki Paulina Uribe Ricardo Badilla-Ohlbaum 《Applied microbiology》1988,54(7):1694-1699
The oxidation of ferrous iron and elemental sulfur by Thiobacillus ferrooxidans that was absorbed and unabsorbed onto the surface of sulfur prills was studied. Unadsorbed sulfur-grown cells oxidized ferrous iron at a rate that was 3 to 7 times slower than that of ferrous iron-grown cells, but sulfur-grown cells were able to reach the oxidation rate of the ferrous iron-adapted cells after only 1.5 generations in a medium containing ferrous iron. Bacteria that were adsorbed to sulfur prills oxidized ferrous iron at a rate similar to that of unadsorbed sulfur-grown bacteria. They also showed the enhancement of ferrous iron oxidation activity in the presence of ferrous iron, even though sulfur continued to be available to the bacteria in this case. An increase in the level of rusticyanin together with the enhancement of the ferrous iron oxidation rate were observed in both sulfur-adsorbed and unadsorbed cells. On the other hand, sulfur oxidation by the adsorbed bacteria was not affected by the presence of ferrous iron in the medium. When bacteria that were adsorbed to sulfur prills were grown at a higher pH (ca. 2.5) in the presence of ferrous iron, they rapidly lost both ferrous iron and sulfur oxidation capacities and became inactive, apparently because of the deposition of a jarosite-like precipitate onto the surface to which they were attached. 相似文献
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J Aleksandrowicz M Jankowski 《Journal of hygiene, epidemiology, microbiology, and immunology》1986,30(3):309-316
Seventy-four batches of normal human immunoglobulin of placental origin (NHIp) and 25 batches of the preparation derived from the serum (NHIs) were tested. The batches were divided into groups (A-E) according to production date and presence of sediment. The degree of degradation of NHI preparations was determined measuring the components soluble in trichloroacetic acid (TCASC), performing molecular filtration or carrying out electrophoresis in polyacrylamide gel. The level of antibodies to measles virus was determined with the enzymatic immunoadsorption test (ELISA) and haemagglutination inhibition test (HIT). It was found that NHI preparations were undergoing significant degradation before their expiration date. The content of TCASC ranged from 1.83% for NHIs preparations recently produced (group E) to 10.57-10.63% respectively in NHIp preparations with sediment (groups B and A). Molecular filtration made possible isolation of a polymer, a monomer, and degradation products. The level of antibodies against measles virus was the lower (7,400) the greater was the degree of degradation of NHIp preparations in the relation of NHI preparations recently produced (21,500). 相似文献
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Edgar Antonio Rodríguez-Negrete Enrique Alejandro Guevara-Rivera Ángela Paulina Arce-Leal Norma Elena Leyva-López Jesús Méndez-Lozano 《Molecular Plant Pathology》2023,24(10):1300-1311
The nonstructural protein NSm of tomato spotted wilt virus (TSWV) has been identified as the avirulence determinant of the tomato single dominant Sw-5 resistance gene. Although Sw-5 effectiveness has been shown for most TSWV isolates, the emergence of resistance-breaking (RB) isolates has been observed. It is strongly associated with two point mutations (C118Y or T120N) in the NSm viral protein. TSWV-like symptoms were observed in tomato crop cultivars (+Sw-5) in the Baja California peninsula, Mexico, and molecular methods confirmed the presence of TSWV. Sequence analysis of the NSm 118–120 motif and three-dimensional protein modelling exhibited a noncanonical C118F substitution in seven isolates, suggesting that this substitution could emulate the C118Y-related RB phenotype. Furthermore, phylogenetic and molecular analysis of the full-length genome (TSWV-MX) revealed its reassortment-related evolution and confirmed that putative RB-related features are restricted to the NSm protein. Biological and mutational NSm 118 residue assays in tomato (+Sw-5) confirmed the RB nature of TSWV-MX isolate, and the F118 residue plays a critical role in the RB phenotype. The discovery of a novel TSWV-RB Mexican isolate with the presence of C118F substitution highlights a not previously described viral adaptation in the genus Orthotospovirus, and hence, the necessity of further crop monitoring to alert the establishment of novel RB isolates in cultivated tomatoes. 相似文献
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Leentje Goosen-de Roo R. Bakhuizen Paulina C. van Spronsen K. R. Libbenga 《Protoplasma》1984,122(1-2):145-152
Summary Fusiform cambial cells of the ash (Fraxinus excelsior L.), which are strongly elongated and vacuolated, contain a phragmosome which traverses the whole length of the cells during preprophase and karyokinesis and which remains present during cytokinesis until it is integrated in cell plate with adjacent cytoplasm.The phragmosome consists of a thin perforated cytoplasmic layer located in the plane of the future cell plate. Otherwise oriented transvacuolar cytoplasmic layers or strands are not present in these cells.The phragmosome contains cytoskeletal elements, namely microtubules and also microfilament bundles both of which are oriented mainly in longitudinal direction.The phragmosomal microtubules are a new category of microtubules associated with cell division; presumably they guide the centrifugally growing cell plate to the parental cell wall site previously marked by the preprophase band of microtubules. 相似文献
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Partially purified prostacyclin synthase from pig aorta converted the prostaglandin (PG) endoperoxide PGH2 to prostacyclin (PGI2), and PGH1 to 12-hydroxy-8,10-heptadecadienoic acid (HHD). Both reactions were inhibited by 15-hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HP) in a dose-dependent fashion. However, the reactions PGH2 → PGI2 and PGH1 → HHD appeared to differ: substrate availability was rate limiting in the latter reaction, while the enzyme became rapidly saturated with PGH2 and a steady rate of prostacyclin formation was observed at higher substrate levels. 相似文献
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