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81.
Belgin Küçükkaya Goncagül Haklar Prof. Dr. A. Süha Yalçin 《Neurochemical research》1996,21(12):1535-1538
NMDA, the specific agonist of glutamate gated ion channels permeable to calcium, is implicated as a causal factor in the pathogenesis
of several neurobiological disorders such as stroke, seizures, ischemia, and chronic neurodegenerative disease. On the other
hand, evidence on the roles of oxidative mechanisms involved in NMDA-induced neurotoxicity is accumulating. In this study,
we have used chemiluminescence measurements as an easy, rapid and sensitive assay to investigate the effects of NMDA and oxidative
stress on brain cell vulnerability. Rat brain homogenates were incubated with increasing concentrations of glutamate and NMDA.
Production of reactive oxygen species was followed by single photon emission measurements using the specific enhancers luminol
and lucigenin. Increases in emission were observed at excitotoxic concentrations of glutamate and NMDA. Other parameters of
oxidative stress such as diene conjugates, TBARS and carbonyl groups were also investigated. Our results indicated that chemiluminescence
measurements may be used to study involvement of oxidative stress in neurotoxicity. 相似文献
82.
Identification and expression of water stress- and abscisic acid-regulated genes in a drought-tolerant sunflower genotype 总被引:17,自引:0,他引:17
83.
Molecular cloning of the lectin and a lectin-related protein from common Solomon's seal (Polygonatum multiflorum) 总被引:3,自引:0,他引:3
Els J. M. Van Damme Annick Barre Pierre Rougé Fred Van Leuven Jan Balzarini Willy J. Peumans 《Plant molecular biology》1996,31(3):657-672
The most prominent protein ofPolygonatum multiflorum (common Solomon's seal) rhizomes has been identified as a mannose-binding lectin. Analysis of the purified lectin demonstrated that it is a tetramer of four identical subunits of 14 kDa. Molecular cloning further revealed that the lectin from this typical Liliaceae species belongs to the superfamily of monocot mannose-binding proteins. Screening of cDNA libraries constructed with RNA isolated from buds, leaves and flowers ofP. multiflorum also yielded cDNA clones encoding a protein, which contains two tandemly arranged domains with an obvious sequence homology to the mannose-binding lectins. Molecular modelling of thePolygonatum lectin and lectin-related protein indicated that the three-dimensional structure of both proteins strongly resembles that of the snowdrop lectin. In addition, this approach suggested that the presumed carbohydrate-binding sites of the lectin can accommodate a mannose residue whereas most of the carbohydratebinding sites of the lectin-related protein cannot.Abbreviations GNA
Galanthus nivalis agglutinin
- HCA
hydrophobic cluster analysis
- LECPMA
cDNA clone encoding PMA
- PM30
30 kDa protein isolated fromPolygonatum multiforum
- PMA
Polygonatum multiflorum agglutinin
- PMLRP
Polygonatum multiflorum lectin-related protein 相似文献
84.
The courtship of 5 jacks was evaluated weekly for 12 mo. The characteristics of sexual behavior were recorded before the collection of 2 ejaculates, at 4-h intervals, into an artificial vagina in the presence of a female in either natural or induced estrus. The maximum time given to the jack to perform the ejaculatory mount was 1 h. If the jacks did not ejaculate, another attempt was made the following week. At the time of collection, the male and female remained free in a paddock (20 m2). The data presented in this study is based on results in which the first and second ejaculates occurred successively. Statistical analysis was done by a 2 x 2 factorial design in randomized blocks. The mean +/- SEM of sexual behavior characteristics for the first and second ejaculate were, respectively: time until first mount = 0.7 +/- 0.2 and 0.9 +/- 0.2 min; time until first erection = 11.9 +/- 1.1 and 11.6 +/- 1.1 min; time until ejaculation = 15.0 +/- 1.2 and 13.6 +/- 1.2 min; frequency of partial exposure of penis = 3.4 +/- 0.4 and 3.2 +/- 0.4; frequency of total exposure of penis = 1.0 + 0.2 and 1.1 +/- 0.2; frequency of flehmen responses = 6.6 +/- 0.5 and 4.6 +/-0.5; frequency of erections = 1.3 +/- 0.1 and 1.2 +/- 0.1; frequency of retreats away from the female = 1.8 +/- 0.2 and 1.0 +/- 0.2; frequency of mounts with erection but without ejaculation = 0.3 +/- 0.1 and 0.1 +/- 0.1; frequency of mounts without erection = 2.0 +/-0.1 and 1.2 +/- 0.1 ; and frequency of pelvic copulatory movements = 4.8 +/- 0.4 and 4.4 +/- 0.4. Individual differences were observed (P<0.05) for partial and total exposure, flehmen responses, mounts without erection and pelvic copulatory movements. The variables flehmen responses, retreats away from the female and mounts without erection showed significant differences (P<0.05) between ejaculates. Seasonal effects on sexual behavior characteristics were not found. However, a monthly effect was noted for flehmen responses, partial exposure of the penis, mounts without erection, retreats away from the female and pelvic copulatory movements when the 2 ejaculates were combined. 相似文献
85.
The effect of reduced oxygen supply on the production of a recombinant protein (plasmid-encoded beta-galactosidase) was investigated in Escherichia coli. A novel modified bubble tank reactor was used to provide a direct comparison between immobilized and suspended cells in identical environments except for the immobilization matrix. Decreased oxygen supply led to increased beta-galactosidase synthesis by both immobilized and suspended cells. Immobilized cells produced similar amounts of beta-galactosidase as the suspended cells. Lactose consumption and acetate production, on a per cell basis, were significantly higher in immobilized cells, suggesting that immobilized cells utilized fermentative metabolism. However, a transport analysis of the immobilized cell system showed that immobilized cells were not subject to either external or internal mass transfer gradients. 相似文献
86.
Françoise Mead Catherine Habersetzer Danielle Gabouriaut Jacques Gervet 《Journal of Ethology》1994,12(1):43-51
This study focused on how a decrease in prey availability affected the development of aP. dominulus Christ colony. Nutritional oophagy and larval development were parameters found to be most directly affected. The more indirect
effects on the growth of the nest and on offspring production were also analyzed. 相似文献
87.
To investigate morphogenesis and in particular circularization mechanisms in young mycelia, we observe cultures of the zygomyceteMucor spinosus and develop discrete models of two-dimensional filamental branching growth. The models are based on the hypothesis that the
fungus secretes a regulatory substance that diffuses into the surrounding medium and is detected by the growing hyphae. We
also present a simple Markovian growth model without such a feedback, but yielding to analytical computations. 相似文献
88.
Charles Coudray Sylvie Pucheu François Boucher Josiane Arnaud Joël de Leiris Alain Favier 《Biological trace element research》1994,41(1-2):69-75
The hypothesis that oxygen-derived free radicals play an important role in myocardial ischemic and reperfusion injury has received a lot of support. In the presence of catalytic amounts of transition metals such as iron, superoxide anions, and hydrogen peroxide can be transformed into a highly reactive hydroxyl radical °OH (Haber-Weiss reaction). In view of this, we have undertaken this study to investigate whether iron is involved in the reperfusion syndrome and therefore could aggravate free radicals injury. Coronary effluent iron concentrations and cardiac cytosolic iron levels were evaluated in rat hearts subjected to an ischemia/reperfusion sequences. In the case of total ischemia, iron concentration in coronary effluents peaked immediately in the first sample collected upon reperfusion. However, in the case of partial ischemia, iron concentration in coronary effluents peaked rather exclusively during ischemia period. Cardiac cytosolic iron level augmented significantly after 30 min of total ischemia and non significantly in the other ischemia protocols compared to perfused control hearts. It also appears that the iron released is not protein-bound, and could therefore have a marked catalytic activity. The results of the present study suggest that in the oxygen paradox, iron plays an important role in inducing alterations during reoxygenation. 相似文献
89.
Laurent Beuf Sylvie Bédu Marie-Claire Durand Françoise Joset 《Plant molecular biology》1994,25(5):855-864
The involvement of a gene ofSynechocystis PCC6803,icfG, in the co-ordinated regulation of inorganic carbon and glucose metabolism, was established. TheicfG gene codes for a 72 kDa protein, which shows no homology with those registered in data libraries. Expression oficfG required glucose, the actual inducer probably being glucose-6-phosphate, and was independent of light and of the external inorganic carbon concentration. Mutants carrying an inactivated copy oficfG were constructed. Their growth characteristics were identical to those of the wild type under all regimes except in limiting inorganic carbon with glucose being present either before or after the transfer to the limiting conditions. These conditions completely prevented growth, both in the light and in the dark. The inhibition could be relieved by several intermediates of the tricarboxylic acid cycle. Assays of various enzymic activities related to inorganic carbon uptake and to its assimilationvia either the Calvin cycle or phosphoenolpyruvate carboxylase did not reveal the level of action of IcfG. Possible models include a blockage of the assimilation of both carbon sources in the absence of IcfG, or the inhibition of Ci incorporation route(s) essential under limiting inorganic carbon conditions, even when glucose is present, and even in the dark. 相似文献
90.
Luís C. Duarte Alexandra P. Nobre Francisco M. Gírio M. T. Amaral-Collaço 《Biotechnology Techniques》1994,8(12):859-864
Summary The kinetic parameters of the yeastDebaryomyces hansenii grown in continous cultivation on D-xylose were determined by different methods. While the values obtained for μm by the steady state and the washout methods only gave a 3% difference, the determined Ks values by the steady state and the maximal biomass output methods led a to a 305% difference. The latter method was suggested
to overestimate the Ks value. 相似文献