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81.
T Kaneko K B Song T Hamamoto T Kudo K Horikoshi 《Journal of general microbiology》1989,135(12):3447-3457
The cyclomaltodextrin glucanotransferase (CGTase, EC 2.4.1.19) gene from the alkalophilic Bacillus sp. strain no. 17-1 was cloned in Escherichia coli. The cloned CGTase gene consisted of a single open reading frame which would encode a polypeptide of 713 amino acids, and the first 27 amino acid residues comprised a signal peptide. The nucleotide sequence and the amino acid sequence of this CGTase (CGTase 17-1) gene had strong homology with those of the CGTase (CGTase 38-2) gene previously cloned in our laboratory from the alkalophilic Bacillus sp. strain no. 38-2, although the enzymic properties of the CGTase 17-1 were distinct from those of the CGTase 38-2. To analyse those enzymic properties further, we constructed 12 chimeric CGTases using three restriction nuclease sites and compared the enzymic properties of the chimeric CGTases. The N-terminal part of the enzyme was important for heat stability, and the pH-activity profile was influenced by both the N- and the C-terminal parts. A third segment was less important for enzymic properties. 相似文献
82.
Control of Continuous Irradiation Injury on Potatoes with Daily Temperature Cycling 总被引:3,自引:0,他引:3 下载免费PDF全文
Two controlled-environment experiments were conducted to determine the effects of temperature fluctuations under continuous irradiation on growth and tuberization of two potato (Solanum tuberosum L.) cultivars, Kennebec and Superior. These cultivars had exhibited chlorotic and stunted growth under continuous irradiation and constant temperatures. The plants were grown for 4 weeks in the first experiment and for 6 weeks in the second experiment. Each experiment was conducted under continuous irradiation of 400 micromoles per square meter per second of photosynthetic photon flux and included two temperature treatments: constant 18°C and fluctuating 22°C/14°C on a 12-hour cycle. A common vapor pressure deficit of 0.62 kilopascal was maintained at all temperatures. Plants under constant 18°C were stunted and had chlorotic and abscised leaves and essentially no tuber formation. Plants grown under the fluctuating temperature treatment developed normally, were developing tubers, and had a fivefold or greater total dry weight as compared with those under the constant temperature. These results suggest that a thermoperiod can allow normal plant growth and tuberization in potato cultivars that are unable to develop effectively under continuous irradiation. 相似文献
83.
Tryptophan (Trp) surface topography of the red- and far-red-absorbing forms of phytochrome (Pr, Pfr) ofAvena sativa L. has been investigated by analyzing quenching of the two components of Trp fluorescence decay, in order to understand the
differences in the two forms at the molecular level. Stern-Volmer kinetic analysis of the quenching data for two cationic
surface quenchers, Cs+ and Tl+, showed strong quenching of the short component of the Pr fluorescence (Stern-Volmer constants,K
sv
, 27.2 and 21.4 M−1, respectively) relative to that of Pfr fluorescenceK
sv
, 10.4 and 12.3 M−1, respectively). The long component of the Trp fluorescence was quenched differentially by Cs+ and Tl+, withK
sv
of 9.0 and 19.8 M−1, respectively, for the Pr fluorescence andK
sv
of 13.7 and 8.7 M−1, respectively, for the Pfr fluorescence. The results indicate that the phytochrome Trp residues with short fluorescence lifetime
are more accessible to the cationic surface quenchers than those with long fluorescence lifetime. The data, taken together
with our earlier study (Singh et al. 1988, Biochim, Biophys. Acta936, 395–405), indicate that most, if not all the ten Trp residues of phytochrome, are fluorescent and exist in distinct groups
differing in their topography and microenvironment, and the peptide segment containing Trp-774 and Trp-778 within the 55-kilodalton
C-terminal domain of phytochrome also undergoes a subtle alteration in its surface topography during Pr→Pfr phototransformation.
This paper is dedicated to Professor Hans Mohr in commemoration of his 60th birthday 相似文献
84.
K. Song T. C. Osborn P. H. Williams 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,79(4):497-506
Summary RFLPs were used to study genome evolution and phylogeny in Brassica and related genera. Thirtyeight accessions, including 10 accessions of B. rapa (syn. campestris), 9 cultivated types of B. oleracea, 13 nine-chromosome wild brassicas related to B. oleracea, and 6 other species in Brassica and allied genera, were examined with more then 30 random genomic DNA probes, which identified RFLPs mapping to nine different linkage groups of the B. rapa genome. Based on the RFLP data, phylogenetic trees were constructed using the PAUP microcomputer program. Within B. rapa, accessions of pak choi, narinosa, and Chinese cabbage from East Asia constituted a group distinct from turnip and wild European populations, consistent with the hypothesis that B. rapa had two centers of domestication. A wild B. rapa accession from India was positioned in the tree between European types and East Asian types, suggesting an evolutionary pathway from Europe to India, then to South China. Cultivated B. oleracea morphotypes showed monophyletic origin with wild B. oleracea or B. alboglabra as possible ancestors. Various kales constitute a highly diverse group, and represent the primitive morphotypes of cultivated B. oleracea from which cabbage, broccoli, cauliflower, etc. probably have evolved. Cauliflower was found to be closely related to broccoli, whereas cabbage was closely related to leafy kales. A great diversity existed among the 13 collections of nine-chromosome wild brassicas related to B. oleracea, representing various taxonomic states from subspecies to species. Results from these studies suggested that two basic evolutionary pathways exist for the diploid species examined. One pathway gave rise to B. fruticulosa, B. nigra, and Sinapis arvensis, with B. adpressa or a close relative as the initial ancestor. Another pathway gave rise to B. oleracea and B. rapa, with Diplotaxis erucoides or a close relative as the initial ancestor. Raphanus sativus and Eruca sativus represented intermediate types between the two lineages, and might have been derived from introgression or hybridization between species belonging to different lineages. Molecular evidence for an ascending order of chromosome numbers in the evolution of Brassica and allied genera was obtained on the basis of RFLP data and phylogenetic analysis. 相似文献
85.
86.
87.
K S Park D H Sohn R L Veech B J Song 《Biochemical and biophysical research communications》1992,185(2):676-682
Pentoxyresorufin O-depentylase activity, mainly associated with phenobarbital-inducible cytochrome P450IIB1 (designated CYP2B1), was increased after a single treatment of pyridine (250 mg/kg, i.p.), and further increased by repeated treatments for 5 days. The catalytic activity and immunoreactive protein of CYP2B recognized by polyclonal antibodies were significantly induced by a relatively high dose of pyridine (250 mg/kg, i.p.) while ethanol-inducible cytochrome P450IIE1 (CYP2E1) could be induced by a low dosage (25 mg/kg, i.p.). Unlike CYP2E1 induction without changing its mRNA level, the induction of CYP2B by pyridine was accompanied by an elevation of its mRNA, indicating a pre-translational activation of this enzyme. These results indicate that pyridine induces various isozymes of cytochromes P450 by different induction mechanisms. 相似文献
88.
厚朴类有效成分的含量测定及高效液相色谱图 总被引:9,自引:0,他引:9
用高效液相色谱法对我国木兰科植物“厚朴类”中的酚类和季胺碱类作了定性和定量分析,并提供色谱图,结果表明不同产地的“厚朴”,图谱相同,仅含量有差别,但不同种的“厚朴”,色谱图不同.此结果可作为评价“厚朴类“药材质量和鉴别的方法.根据各类厚朴有效成分的存在,有一定的规律,为木兰科植物化学分类提供了有价值的资料。 相似文献
89.
本文对国内流行的猪肠毒素源性大肠杆菌K88ac抗原的结构基因的核苷酸序列进行了测定。该基因由849对核苷酸组成,编码了283个氨基酸的蛋白亚单位及21个氨基酸的信号肽。与国外报道的K88ac序列的不同是我们发现一个碱基的点突变,导致在抗原决定簇内一个氨基酸的改变。从核苷酸序列推导出的氨基酸序列与另两种亚型进行了比较。 相似文献
90.
Helper virus-free transfer of herpes simplex virus type 1 plasmid vectors into neural cells. 总被引:11,自引:2,他引:9 下载免费PDF全文
C Fraefel S Song F Lim P Lang L Yu Y Wang P Wild A I Geller 《Journal of virology》1996,70(10):7190-7197
Herpes simplex virus type 1 (HSV-1) plasmid vectors have promise for genetic intervention in the brain, but several problems caused by the helper virus have compromised their utility. To develop a helper virus-free packaging system for these vectors, the DNA cleavage/packaging signals were deleted from a set of cosmids that represents the HSV-1 genome. Following cotransfection into cells, this modified cosmid set supported replication and packaging of vector DNA. However, in the absence of the DNA cleavage/packaging signals, the HSV-1 genome was not packaged, and consequently vector stocks were free of detectable helper virus. In the absence of helper virus, the vectors efficiently infected rat neural cells in culture or in the brain with minimal cytopathic effects. beta-galactosidase-positive cells were observed for at least 1 month in vivo, and vector DNA persisted for this period. This system may facilitate studies on neuronal physiology and potential therapeutic applications. 相似文献