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31.
Wei Zhang David J. Chapman Bernard O. Phinney Clive R. Spray Hisakazu Yamane Nobutaka Takahashi 《Journal of phycology》1991,27(1):87-91
Combined gas chromatography-mass spectrometry (GCMS) was used to identify and quantify specific cytokinins from Porphyra perforate J. Ag. and Sargassum muticum (Yendo) Fensh. The level of isopentenyladenosine was estimated to be 0.6 μ·kg?1 fresh weight in Porphyra and 0.9 μ·kg?1 fresh weight in Sargassum. The level of cis-zeatin riboside was estimated to be 0.2 μ·kg?1 fresh weight in Sargassum. This is the first definitive identification of a cytokinin from a red alga, and the second report from a brown alga. 相似文献
32.
Robin A. Clark Clive J. Fox David Viner† Matthew Livermore† 《Global Change Biology》2003,9(11):1669-1680
In order to examine the likely impacts of climate change on fish stocks, it is necessary to couple the output from large‐scale climate models to fisheries population simulations. Using projections of future North Sea surface temperatures for the period 2000–2050 from the Hadley General Circulation Model, we estimate the likely effects of climate change on the North Sea cod population. Output from the model suggests that increasing temperatures will lead to an increased rate of decline in the North Sea cod population compared with simulations that ignore environmental change. Although the simulation developed here is relatively simplistic, we demonstrate that inclusion of environmental factors in population models can markedly alter one's perception of how the population will behave. The development of simulations incorporating environment effects will become increasingly important as the impacts of climate change on the marine ecosystem become more pronounced. 相似文献
33.
Barry K Derham J Clive Ellory Anthony J Bron John J Harding 《European journal of biochemistry》2003,270(12):2605-2611
Alpha-crystallin, a molecular chaperone and lens structural protein protects soluble enzymes against heat-induced aggregation and inactivation by a variety of molecules. In this study we investigated the chaperone function of alpha-crystallin in a more physiological system in which alpha-crystallin was incorporated into red cell 'ghosts'. Its ability to protect the intrinsic membrane protein Na/K-ATPase from external stresses was studied. Red cell ghosts were created by lysing the red cells and removing cytoplasmic contents by size-exclusion chromatography. The resulting ghost cells retain Na/K-ATPase activity. alpha-Crystallin was incorporated in the cells on resealing and the activity of Na/K-ATPase assessed by ouabain-sensitive 86Rb uptake. Incubation with fructose, hydrogen peroxide and methylglyoxal (compounds that have been implicated in diabetes and cataract formation) were used to test inactivation of the Na/K pump. Intracellular alpha-crystallin protected against the decrease in ouabain sensitive 86Rb uptake, and therefore against inactivation induced by all external modifiers, in a dose-dependent manner. 相似文献
34.
Intraspecific variation of four agamospecies ofHieracium sect.Alpina was studied using RAPD and isozyme techniques. No variation in either multiprimer RAPD or multi-enzyme phenotypes was observed withinH. holosericeum, suggesting that this widespread species consists of only a single genotype. A low level of within-population isozyme variation was seen inH. tenuifrons andH. calenduliflorum, the origin of which appears to be consistent with somatic mutation. Most isozyme and all RAPD variation in these two species was partitioned between populations. A strong correlation with geography suggests that its cause may be due to polytopic (-polyphyletic?) origin or perhaps to mutation and dispersal. The most variable species wasH. alpinum, in which isozyme variation occurred mostly within populations rather than between them, suggesting occasional sexual events or that the parents ofH. alpinum were heterozygous. RAPD variation in this species, in contrast, was partitioned between Scottish and Swiss populations, suggesting the existence of geographical races. 相似文献
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Peter R. Dodd Gregory J. Thomas Clive G. Harper Jillian J. Kril 《Journal of neurochemistry》1992,59(4):1506-1515
Gamma-aminobutyric acidA/benzodiazepine receptor binding sites and the N-methyl-D-aspartate subclass of glutamate receptor sites were assessed in synaptic plasma membrane homogenates of cerebral cortex tissue obtained at autopsy from cirrhotic and noncirrhotic alcoholic patients and matched control subjects. The alcoholic patients consumed an average of greater than 80 g of ethanol/day, the control subjects less than 20 g/day. Postmortem delays up to approximately 100 h caused no significant loss of any of the binding sites; the patient and subject groups were closely matched for age. The affinities (KD) of the receptor sites did not differ between the patient and subject groups, nor between cortical regions. Using three different radioligands ([3H]muscimol, [3H]flunitrazepam, and [3H]diazepam), the gamma-aminobutyric acidA/benzodiazepine receptor complex was found to have greater density (Bmax) in superior frontal gyrus in alcoholic patients (which selectively shows morphological change in alcoholic patients), but was unchanged in motor cortex. Alcoholic patients with cirrhosis had much less pronounced changes. The density of the N-methyl-D-aspartate subclass of glutamate receptors, assessed with [3H]MK-801, did not vary across patient and subject groups. 相似文献
38.
Micro-element deficiencies have been implicated in the development of poor stem form in Pinus radiata plantations. Cu, Mn and B have been implicated in previous studies as influencing tree form and/or the process of lignification in plants. Therefore an experiment was initiated to examine the individual and interactive effects exhibited by these trace elements on stem form and lignification.The investigation showed that Cu deficiency reduced both lignification and stem form in seedlings. Mn, competing with Cu for uptake, enhanced the symptoms of Cu deficiency. Boron addition did not alleviate the expression of deformity or increase levels of lignification. There was a clear family influence on the development of seedling stem form in response to variations in mineral nutrition. 相似文献
39.
Localization of the mouse thymidine kinase gene to the distal portion of chromosome 11 总被引:3,自引:0,他引:3
We report the cytogenetic mapping of the thymidine kinase (tk-1) gene in the mouse using two complementary and independent analyses: (1) investigation of chromosome aberrations associated with tk-1 gene inactivation in the L5178Y TK+/- -3.7.2C cell line, and (2) fluorescence in situ molecular hybridization of cloned tk-1 cDNA probes to mitotic chromosomes of this cell line. The consensus location from both analyses is 11E1-E2. Consideration of the mouse tk-1 gene localization, along with evidence that the homologous human TK1 gene is located distally on the large arm of chromosome 17, appears to extend the region of homology between MMU11 and HSA17 to the distal end of both chromosomes. 相似文献
40.