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排序方式: 共有391条查询结果,搜索用时 312 毫秒
1.
Cysteine: Depolarization-Induced Release from Rat Brain In Vitro 总被引:3,自引:2,他引:1
Hans Jörg Keller Kim Quang Do Markus Zollinger Kaspar H. Winterhalter Michel Cuénod 《Journal of neurochemistry》1989,52(6):1801-1806
Compounds released on depolarization in a Ca2+-dependent manner from rat brain slices were screened to identify candidates for neuroactive substances. Lyophilized superfusates were analyzed by reversed-phase HPLC after derivatization with 9-fluorenyl N-succinimidyl carbonate. One of the compounds that showed an increase of concentration in superfusates in the presence of iodoacetamide was identified as the cysteine (Cys) derivative, S-carboxamidomethylcysteine, by fast atom bombardment mass spectrometry and other methods. This stable Cys derivative originates from endogenous, extracellular Cys. The finding led to a method for quantification of Cys in superfusates by immediate cooling of the superfusates to 0 degrees C and reaction of Cys with N-ethylmaleimide. Depolarization-induced Ca2+-dependent release of Cys was most prominent in the neocortex, followed by the mesodiencephalon, striatum, and cerebellum. This suggests that Cys is released from a neuronal compartment and might be involved in neurotransmission. 相似文献
2.
The carrageenan-producing red algaKappaphycus alvarezii (Doty) Doty was brought to Vietnam from Japan in 1993. Branch fragments of this species were cultivated in a pond, lagoon, inlet and offshore in Vietnam for the first time. The best daily growth rate (DGR) of plants grown in the lagoon area attained 9–11 % day–1 in May to June (cold season). The water temperature and salinity in this area ranged from 27.2–32.4 °C and 31.4–33.7 °C, respectively. DGR of plants grown in the inlet ranged from 7 to 9% day–1 in June. Grazing by fish has been observed to occur in this area. The DGR of plants grown in the pond ranged from 5–6% in January–July, but decreased to less than 4% day–1 in August (hot season).
K. alvarezii in Vietnam showed a carrageenan yield of 18.8–24.6% and gel strength of 1566–1712 g cm–2. These values are similar ones obtained fromK. alvarezii cultivated in the Philippines and Indonesia. 相似文献
3.
Viability and Isolation of Marine Bacteria by Dilution Culture: Theory, Procedures, and Initial Results 总被引:30,自引:21,他引:9 下载免费PDF全文
D. K. Button Frits Schut Pham Quang Ravonna Martin Betsy R. Robertson 《Applied microbiology》1993,59(3):881-891
Dilution culture, a method for growing the typical small bacteria from natural aquatic assemblages, has been developed. Each of 11 experimental trials of the technique was successful. Populations are measured, diluted to a small and known number of cells, inoculated into unamended sterilized seawater, and examined three times for the presence of 104 or more cells per ml over a 9-week interval. Mean viability for assemblage members is obtained from the frequency of growth, and many of the cultures produced are pure. Statistical formulations for determining viability and the frequency of pure culture production are derived. Formulations for associated errors are derived as well. Computer simulations of experiments agreed with computed values within the expected error, which verified the formulations. These led to strategies for optimizing viability determinations and pure culture production. Viabilities were usually between 2 and 60% and decreased with >5 mg of amino acids per liter as carbon. In view of difficulties in growing marine oligobacteria, these high values are noteworthy. Significant differences in population characteristics during growth, observed by high-resolution flow cytometry, suggested substantial population diversity. Growth of total populations as well as of cytometry-resolved subpopulations sometimes were truncated at levels of near 104 cells per ml, showing that viable cells could escape detection. Viability is therefore defined as the ability to grow to that population; true viabilities could be even higher. Doubling times, based on whole populations as well as individual subpopulations, were in the 1-day to 1-week range. Data were examined for changes in viability with dilution suggesting cell-cell interactions, but none could be confirmed. The frequency of pure culture production can be adjusted by inoculum size if the viability is known. These apparently pure cultures produced retained the size and apparent DNA-content characteristic of the bulk of the organisms in the parent seawater. Three cultures are now available, two of which have been carried for 3 years. The method is thus seen as a useful step for improving our understanding of typical aquatic organisms. 相似文献
4.
S-Nitrosoglutathione in Rat Cerebellum: Identification and Quantification by Liquid Chromatography-Mass Spectrometry 总被引:1,自引:0,他引:1
Ina Kluge Ursula Gutteck-Amsler Markus Zollinger Kim Quang Do 《Journal of neurochemistry》1997,69(6):2599-2607
Abstract: Given the extreme lability and the facile inactivation of the messenger nitric oxide (NO) by many reactive biochemical species, it has been suggested that some intermediate compounds, for example, S -nitrosothiols, may act to stabilize NO and at the same time to preserve its biological activity. To test this hypothesis, we investigated if the S -nitrosothiol of glutathione, which is the predominant low molecular weight thiol in CNS, is present in the rat brain. The HPLC analysis of cerebellar extract from [35 S]cysteine-prelabeled slices suggested that S -nitrosoglutathione (GSNO) was indeed present in rat brain. To detect endogenous GSNO, a methodology based on liquid chromatography-mass spectrometry was developed. Besides an unequivocal identification of the endogenous GSNO, this method also permitted its precise quantification using 15 N-labeled GSNO ([15 N]-GSNO) as internal standard. GSNO level in adult cerebellum amounts to 15.4 ± 1.4 pmol/mg of protein. This is the first direct demonstration of the presence of endogenous GSNO in CNS. The packaging of NO in the form of GSNO might serve to facilitate its transport, prolong its life, and target its delivery to specific effectors. 相似文献
5.
Quang Khai Huynh Ryuzo Sakakibara Takehiko Watanabe Hiroshi Wada 《Biochemical and biophysical research communications》1980,97(2):474-479
The complete amino acid sequence of the mitochondrial glutamic oxaloacetic transaminase isozyme from rat liver is presented. The sequence contained 401 amino acid residues, 10 of which are methionine. Cyanogen bromide cleavage of mitochondrial glutamic oxaloacetic transaminase produced 12 peptides, one of which contained an internal homoserine residue resulting from incomplete cleavage by cyanogen bromide. The calculated molecular weight was 44,358. The sequence showed 94% homology with that of the corresponding isozyme from pig heart. These findings support the conclusion that the rate of evolution of the mitochondrial isozymes is lower than that of their cytosolic isozymes. 相似文献
6.
Do Quang Binh László E. Heszky Gabor Gyulai Anikó Csillag 《Plant Cell, Tissue and Organ Culture》1992,29(2):75-82
Cells of a 2-year-old suspension culture of rice (Oryza sativa L.), grown under 1.5% NaCl stress for 3 months, gave rise to plants through embryogenesis in different saline conditions. The high regeneration potential (59.6%) on salt-free medium decreased rapidly with increasing concentration of salt in the regeneration medium. At 1.25% NaCl, healthy shoots were developed in 14.9% of the cultures. Under 1.5% salt stress, embryo formation and embryo germination (6.1%) was observed but further development into plants was inhibited. Cells not pretreated with salt produced plants at a low frequency (2.6–4.2%) both in salt-free and low saline condition (0.75–1% NaCl). Cells pretreated for 3 months with 0.75% salt did not give rise to plants on all tested media. Plants regenerated from the salt-stressed cultures were transferred to soil and grew to maturity in a greenhouse.Abbreviations BA
6-benzyladenine
- CH
casein hydrolysate
- 2,4-D
2,4-dichlorophenoxyacetic acid
- NAA
1-naphthaleneacetic acid 相似文献
7.
Dung Quang Nguyen Dominik Schneider Nicole Brinkmann Bin Song Dennis Janz Ingo Schöning Rolf Daniel Rodica Pena Andrea Polle 《Environmental microbiology》2020,22(8):3081-3095
Root-associated fungi (RAF) link nutrient fluxes between soil and roots and thus play important roles in ecosystem functioning. To enhance our understanding of the factors that control RAF, we fitted statistical models to explain variation in RAF community structure using data from 150 temperate forest sites covering a broad range of environmental conditions and chemical root traits. We found that variation in RAF communities was related to both root traits (e.g., cations, carbohydrates, NO3−) and soil properties (pH, cations, moisture, C/N). The identified drivers were the combined result of distinct response patterns of fungal taxa (determined at the rank of orders) to biotic and abiotic factors. Our results support that RAF community variation is related to evolutionary adaptedness of fungal lineages and consequently, drivers of RAF communities are context-dependent. 相似文献
8.
Robert Bagchi Mike Crosby Brian Huntley David G. Hole Stuart H. M. Butchart Yvonne Collingham Mohit Kalra Jagadish Rajkumar Asad Rahmani Mitra Pandey Hum Gurung Le Trong Trai Nguyen Van Quang Stephen G. Willis 《Global Change Biology》2013,19(4):1236-1248
We forecasted potential impacts of climate change on the ability of a network of key sites for bird conservation (Important Bird Areas; IBAs) to provide suitable climate for 370 bird species of current conservation concern in two Asian biodiversity hotspots: the Eastern Himalaya and Lower Mekong. Comparable studies have largely not accounted for uncertainty, which may lead to inappropriate conclusions. We quantified the contribution of four sources of variation (choice of general circulation models, emission scenarios and species distribution modelling methods and variation in species distribution data) to uncertainty in forecasts and tested if our projections were robust to these uncertainties. Declines in the availability of suitable climate within the IBA network by 2100 were forecast as ‘extremely likely’ for 45% of species, whereas increases were projected for only 2%. Thus, we predict almost 24 times as many ‘losers’ as ‘winners’. However, for no species was suitable climate ‘extremely likely’ to be completely lost from the network. Considerable turnover (median = 43%, 95% CI = 35–69%) in species compositions of most IBAs were projected by 2100. Climatic conditions in 47% of IBAs were projected as ‘extremely likely’ to become suitable for fewer priority species. However, no IBA was forecast to become suitable for more species. Variation among General Circulation Models and Species Distribution Models contributed most to uncertainty among forecasts. This uncertainty precluded firm conclusions for 53% of species and IBAs because 95% confidence intervals included projections of no change. Considering this uncertainty, however, allows robust recommendations concerning the remaining species and IBAs. Overall, while the IBA network will continue to sustain bird conservation, climate change will modify which species each site will be suitable for. Thus, adaptive management of the network, including modified site conservation strategies and facilitating species' movement among sites, is critical to ensure effective future conservation. 相似文献
9.
Nguyen Hoang Loc Le My Tieu Ngoc Tran Thuy Lan Le Quoc Viet Le Duc Thao Hoang Tan Quang Dinh Thi Bich Lan Phung Thang Long 《Indian journal of microbiology》2013,53(4):488-491
We cloned two genes coding F107-C and K88-1NT fimbrial subunits from strains E. coli C and 1NT isolated from Thua Thien Hue province, Vietnam. The mature peptide of faeG gene from strain E. coli 1NT (called faeG-1NT) is 100 % similarity with faeG gene, while the CDS of fedA gene from strain C (called fedA-C) has a similarity of 97 % with the fedA gene. Expression of the faeG-1NT and fedA-C genes in E. coli BL21 Star™ (DE3) produced proteins of ~31 and 22 kDa, respectively. The effect of IPTG concentration on the K88-1NT and F107-C fimbriae production was investigated. The results showed that 0.5 mM IPTG is suitable for higher expression of K88-1NT subunit, while 0.75 mM IPTG strongly stimulated expression of F107-C subunit. The optimal induction time for expression was also examined. Generally, highest expression of K88-1NT subunit occurred after 6 h of induction, while that of F107-C subunit is after 14 h. 相似文献
10.
报道了越南木樨科(Oleaceae)植物1 新记录种大果素馨(Jasminum macrocarpum Merr.).该种产自越南中南部嘉来省的K’Bang, Kon Ha Nung 地区, 凭证标本保存在 HN, IBSC. 相似文献