共查询到19条相似文献,搜索用时 62 毫秒
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趋磁细菌及磁小体研究的回顾和展望 总被引:2,自引:0,他引:2
趋磁细菌及磁小体研究的回顾和展望陈明杰,卫扬保(武汉大学生命科学学院微生物学与免疫学系.武汉430072)一趋磁细菌研究现状1趋磁细菌的发现1975年,美国人Blakemore在显微镜下观察湖泊底部污泥的富集样品时,发现有一类细菌总是聚集在视野的靠北... 相似文献
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趋磁性细菌是一种由于体内含有对磁场具有敏感性的磁小体,而能够沿着磁力线运动的特殊细菌,本文综述了趋磁细菌的分布、分类、特性、磁小体研究以及趋磁细菌在生物导航方面的研究进展. 相似文献
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趋磁性细菌是一种由于体内含有对磁场具有敏感性的磁小体,而能够沿着磁力线运动的特殊细菌,本文综述了趋磁细菌的分布、分类、特性、磁小体研究以及趋磁细菌在生物导航方面的研究进展。 相似文献
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细菌的运动性是影响其生存及致病的一个关键条件,同时也为合成和开发仿生运动体、微型机器人等提供了有效的模型.趋磁细菌具有胞内磁小体从而能够感知磁场的变化,进而影响其运动行为.目前,这种外部磁场与生物体的远程响应模式已在环境、医疗、材料等领域有广泛应用.因此,聚焦于趋磁细菌的运动特性,综述了趋磁细菌运动行为的表征、运动机理... 相似文献
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Naoyuki Iwabe Kei-ichi Kuma Hirohisa Kishino Masami Hasegawa Takashi Miyata 《Journal of molecular evolution》1990,31(3):205-210
Summary Both the mouse cytosolic malate dehydrogenase gene and its mitochondrial counterpart contain eight introns, of which two are present at identical positions between the isozyme genes. The probability that the two intron positions coincide by chance between the two genes has been shown to be significantly small (=1.3×10–3), suggesting that the conservation of the intron positions has a biological significance. On the basis of a rooted phylogenetic tree inferred from a comparison of these isozymes and lactate dehydrogenases, we have shown that the origins of the conserved introns are very old, possibly going back to a date before the divergence of eubacteria, archaebacteria, and eukaryotes. In the aspartate aminotransferase isozyme genes, five of the introns are at identical places. The origins of the five conserved introns, however, are not obvious at present. It remains possible that some or all of the conserved introns have evolved after the divergence of eubacteria and eukaryotes. 相似文献
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Siderophore production by the magnetic bacterium Magnetospirillum magneticum AMB-1 is elicited by sufficient iron rather than by iron starvation. In order to clarify this unusual pattern, siderophore production was monitored in parallel to iron assimilation using the chrome azurol sulfonate assay and the ferrozine method respectively. Iron concentration lowered approximately five times less than its initial concentration only within 4 h post-inoculation, rendering the medium iron deficient. A concentration of at least 6 microM Fe(3+) is required to initiate siderophore production. The propensity of M. magneticum AMB-1 for the assimilation of large amounts of iron accounts for the rapid depletion of iron in the medium, thereby triggering siderophore excretion. M. magneticum AMB-1 produces both hydroxamate and catechol siderophores. 相似文献
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Robert J. Kraaijenhagen Gert Rijksen Gerard E.J. Staal 《Biochimica et Biophysica Acta (BBA)/General Subjects》1980,631(3):402-411
The glycolytic enzyme hexokinase is studied in cultured leukemic lymphoblasts, in normal lymphocytes and in lymphoblasts obtained by stimulation of normal lymphocytes with phytohaemagglutinin.Hexokinase activity levels in cultured lymphoblasts and in normal lymphocytes are identical, but somewhat higher levels are found in stimulated lymphocytes. Cultured leukemic lymphoblasts differ in isozyme content in comparison to the other lymphoid cells. Besides hexokinase I, which is detected in all the lymphoid cells, they are characterized by the presence of hexokinase II. The concentration of type II increases during cell growth. Another difference between leukemic lymphoblasts and mature and stimulated lymphocytes is found in the regulatory properties of hexokinase I. Hexokinase I from both normal and stimulated lymphocytes is inhibited by glucose-1,6-diphosphate. This inhibition is decreased in part by addition of inorganic phosphate. Hexokinase I from leukemic lymphocytes, however, is inhibited to a lesser extent by glucose-1,6-diphosphate. Inorganic phosphate has no effect at all on this inhibition.In accordance with these findings a different pattern in the hexokinase I region was detected in electrophoresis with several cell types. The subisozyme hexokinase Ib, which appears to be the phosphate-regulated form, is predominant in lymphocytes, whereas it is present in a minor fraction in the cultured leukemic lymphoblasts. In these cells hexokinase Ic predominates. 相似文献
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Two structurally different monomeric and dimeric types of isocitrate dehydrogenase (IDH; EC 1.1.1.42) isozymes were confirmed to exist in a psychrophilic bacterium, Colwellia psychrerythraea, by Western blot analysis and the genes encoding them were cloned and sequenced. Open reading frames of the genes (icd-M and icd-D) encoding the monomeric and dimeric IDHs of this bacterium, IDH-M and IDH-D, were 2,232 and 1,251 bp in length and corresponded to polypeptides composed of 743 and 416 amino acids, respectively. The deduced amino acid sequences of the IDH-M and IDH-D showed high homology with those of monomeric and dimeric IDHs from other bacteria, respectively. Although the two genes were located in tandem, icd-M then icd-D, on the chromosomal DNA, a Northern blot analysis and primer extension experiment revealed that they are transcribed independent of each other. The expression of the monomeric and dimeric IDH isozyme genes in C. maris, a psychrophilic bacterium of the same genus as C. psychrerythraea, is known to be induced by low temperature and acetate, respectively, but no such induction in the expression of the C. psychrerythraea icd-M and icd-D genes was detected. IDH-M and IDH-D overexpressed in Escherichia coli were purified and characterized. In C. psychrerythraea, the IDH-M isozyme is cold-active whereas IDH-D is mesophilic, which is similar to C. maris that contains both cold-adapted and mesophilic isozymes of IDH. Experiments with chimeric enzymes between the cold-adapted monomeric IDHs of C. psychrerythraea and C. maris (IDH-M and ICD-II, respectively) suggested that the C-terminal region of the C. maris IDH-II is involved in its catalytic activity. 相似文献
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J. Salinas A. M. Figueiras M. T. Gonzalez-Jaen C. Benito 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,70(2):192-198
Summary The peroxidase (CPX, PER), -amylase (-AMY), acid and alkaline phosphatase (PHE, PHS) and esterase (EST) zymogram phenotypes of Chinese Spring wheat, Betzes barley and a number of presumptive Betzes chromosome additions to Chinese Spring were determined. It was found that five disomic chromosome addition lines could be distinguished from one another and from the other two possible lines on the basis of the zymogram phenotypes of these isozymes. The structural genes Cpxe-H1 and Cpxe-H2 were located in Betzes chromosome 1, the Perl-H5 and Perl-H6 in chromosome 2, the -Amy-H2 and -Amy-H3 in chromosome 7, the Phs-H5 and Phs-H4 in chromosomes 1 and 3 respectively, the Phe-H2, Phe-H3 and Phe-H4 in chromosome 1, the Phe-H1 in chromosome 3, the Ests-H4, Este-H2 and Ests-H6, Este-H8 in chromosomes 1 and 3 respectively and the Estl-H10 and Estl-H2 structural genes were related to chromosomes 3 and 6 respectively. These gene locations provide evidence of homoeology between Betzes chromosomes 1, 2, 3, 6 and 7 and the rye chromosomes 7, 2, 3, 6 and 5, respectively, and also between Betzes chromosomes 1, 2, 3, 6 and 7 and the Chinese Spring homoeologous groups 7, 2, 3, 6 and 5, respectively. 相似文献
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对极地适冷菌Pseudoalteromonas sp. QI-1产适冷蛋白酶的发酵条件进行优化。结果表明:菌株QI-1的最适生长和产酶温度均为5℃;最佳接种量为1%;发酵培养基的最适初始pH和最佳装样量分别为5和10%;盐度为2%时对菌株的生长和产酶最为有利;麸皮和醋酸钠分别为最佳N源和C源;添加0.75%酪蛋白时菌株QI-1胞外蛋白酶的活性最高;10 mmol/L Mg2+和0.5%Tween-80有利于产酶。正交试验结果表明:菌株Pseudoalteromonassp. QI-1产蛋白酶较佳培养基配方(g/L)为麸皮5,酵母粉2.5,酪蛋白3,MgCl2.6H2O 3,KCl 1.5;发酵液比酶活为166.20 U/mL,较优化前提高了约56%。 相似文献
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磁场对羊草过氧化物酶的激活效应及同工酶分析 总被引:17,自引:0,他引:17
利用外磁场处理羊草种子,并将羊草进行盐(NaCl)碱(Na2CO3)混合胁迫处理,结果表明,磁场处理不仅促进了羊草的生长,而且提高了羊草的抗盐碱性。磁场使羊草过氧化物酶(POD)活性提高,并且诱发了一条新的同工酶带。根据羊草的长势及POD活性分析,确定羊草最佳的磁处理参数是300mT处理,其次是200mT。 相似文献
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Xylanisamajorcomponentforminghemicelluloseandaccountsfor50%ofdryweightofherbaceousplants.Itssourcesareveryabundantintheworld.Xylanisfirstlyhydrolyzedintosmallmolecularxylose,andthenthexylosecanbeutilizedbymicrobesinmaterialcycle.Therearetwowaysforhydrol… 相似文献