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1.
The psbQ gene encoding a 16-kDa polypeptide of the oxygen-evolving complex of photosystem II has been isolated from Arabidopsis thaliana and characterized. The gene consists of a 28 nucleotide long leader sequence, two introns and three exons encoding a 223-amino-acid precursor polypeptide. The first 75 amino acids act as a transit peptide for the translocation of the polypeptide into the thylakoid lumen. Expression studies show that the gene is light-inducible and expresses only in green tissues with high steady-state mRNA levels in leaves. Using this gene as a probe, restriction fragment length polymorphism between two ecotypes, Columbia and Estland, has also been detected. 相似文献
2.
M Hall D K Parker P L Grover J Y Lu N E Hopkins W L Alworth 《Chemico-biological interactions》1990,76(2):181-192
The effects of three aryl acetylenes, 1-ethynylpyrene (EP), 2-ethynylnaphthalene (EN) and 3-ethynylperylene (EPE), upon the metabolism of benzo[a]pyrene (BaP) by microsomes isolated from rat liver were investigated. These aryl acetylenes all inhibited the total metabolism of BaP. Formation of BaP 7,8-dihydrodiol and BaP tetrol products by microsomal preparations from rats that had been pretreated with 3-methylcholanthrene (3MC) were preferentially inhibited. The effects of EP upon the metabolism of BaP 7,8-dihydrodiol by microsomes from rat liver were also studied. This aryl acetylene strongly inhibited the formation of BaP tetrols from BaP 7,8-dihydrodiol by liver microsomes both from untreated rats and from rats pretreated with 3MC, but enhanced the conversion of the BaP dihydrodiol into other metabolites. 相似文献
3.
Control of breathing in Sherpas at low and high altitude 总被引:2,自引:0,他引:2
Hackett P. H.; Reeves J. T.; Reeves C. D.; Grover R. F.; Rennie D. 《Journal of applied physiology》1980,49(3):374-379
4.
Most microfluidic chips utilize off-chip hardware (syringe pumps, computer-controlled solenoid valves, pressure regulators, etc.) to control fluid flow on-chip. This expensive, bulky, and power-consuming hardware severely limits the utility of microfluidic instruments in resource-limited or point-of-care contexts, where the cost, size, and power consumption of the instrument must be limited. In this work, we present a technique for on-chip fluid control that requires no off-chip hardware. We accomplish this by using inert compounds to change the density of one fluid in the chip. If one fluid is made 2% more dense than a second fluid, when the fluids flow together under laminar flow the interface between the fluids quickly reorients to be orthogonal to Earth’s gravitational force. If the channel containing the fluids then splits into two channels, the amount of each fluid flowing into each channel is precisely determined by the angle of the channels relative to gravity. Thus, any fluid can be routed in any direction and mixed in any desired ratio on-chip simply by holding the chip at a certain angle. This approach allows for sophisticated control of on-chip fluids with no off-chip control hardware, significantly reducing the cost of microfluidic instruments in point-of-care or resource-limited settings. 相似文献
5.
Muscular exercise in young men native to 3,100 m altitude 总被引:4,自引:0,他引:4
6.
In vitro pathogenicity tests demonstrated that Hirschmanniella caudacrena is pathogenic to Ceratophyllum demersum (coontail). Symptoms were chlorotic tissue, deformed stems, and, finally, death of the plant. Inoculum densities of 500 nematodes per 5-cm-long cutting in a test tube containing 50 ml of water resulted in death and decay of some of the cuttings within 8 weeks; 100 nematodes killed the plants in 12 weeks, and 50 and 25 nematodes killed them in 16 weeks. The lowest inoculum level of 10 nematodes did not seriously affect the plants at 16 weeks when the experiment was terminated. A second test conducted outdoors in glass jars containing 3 liters of water and two cuttings weighing a total of 15 g fresh weight showed damage, but results were not statistically significant. Hydrilla verticillata inoculated with H. caudacrena was not affected seriously. 相似文献
7.
G J Grover 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1989,192(1):56-60
This study was conducted to determine whether the thromboxane A2 receptor antagonist SQ 30,741 can improve post-ischemic recovery of cardiac function in anesthetized dogs. Saline or SQ 30,741 was infused throughout a 15-min coronary occlusion and 5 hr of reperfusion. Ischemic regional cardiac function was determined using subendocardial ultrasonic crystals. Despite no differences in collateral blood flow or reperfusion flow, SQ 30,741 significantly improved ventricular segmental shortening at all times measured during reperfusion. At 5 hr after the initiation of reperfusion, segmental shortening was 3 +/- 16 and 44 +/- 10% of baseline values for saline and SQ 30,741 groups, respectively. These results implicate thromboxane receptor activation in the pathogenesis of myocardial stunning, and thromboxane antagonists may be useful in mitigating this functional deficit. 相似文献
8.
Metal Ion Interactions with Phosphoenolpyruvate Carboxylase from Crassula argentea and Zea mays 总被引:1,自引:1,他引:0
Metal ion interactions with phosphoenolpyruvate carboxylase from the CAM plant Crassula argentea and the C4 plant Zea mays were kinetically analyzed. Fe2+ and Cd2+ were found to be active metal cofactors along with the previously known active metals Mg2+, Mn2+, and Co2+. In studies with the Crassula enzyme, Mg2+ yielded the highest Vmax value but also generated the highest values of Km(metal) and Km(pep). For these five active metals lower Km(metal) values tended to be associated with lower Km(pep) values. PEP saturation curves showed more kinetic cooperativity than the corresponding metal saturation curves. The activating metal ions all have ionic radii in the range of 0.86 to 1.09 Å. Ca2+, Sr2+, Ba2+, and Ni2+ inhibited competitively with respect to Mg2+, whereas Be2+, Cu2+, Zn2+, and Pd2+ showed mixed-type inhibition. Vmax trends with the five active metals were similar for the C. argentea and Z. mays enzymes except that Cd2+ was less effective with the maize enzyme. Km(metal) values were 10- to 60-fold higher in the enzyme from Z. mays. 相似文献
9.
Neurotrophin expression in rat hippocampal slices: a stimulus paradigm inducing LTP in CA1 evokes increases in BDNF and NT-3 mRNAs. 总被引:28,自引:0,他引:28
We report that stimulation inducing long-term potentiation (LTP) in the CA1 pyramidal cell layer of the hippocampus evokes significant increases in both BDNF and NT-3 mRNAs in CA1 neurons. No changes in BDNF or NT-3 mRNA levels were seen in the nonstimulated regions of the pyramidal cell layer or the dentate. No change was seen in the levels of NGF mRNA at the time point examined. These results suggest that relatively normal levels of activity may regulate region-specific neurotrophin levels in the hippocampus. Given that known effects of NGF (and presumably of BDNF and NT-3) include elevation of neurotransmitter levels, elevation of sodium channels, and promotion of axonal terminal sprouting, activity-associated changes in neurotrophin levels may play a role in regulating neural connections in the adult as well as the developing nervous system. 相似文献
10.
Dolichodorus miradvulvus n. sp. from Anubias nana Engler in Florida is described and illustrated. The female is characterized by deep grooves in the cuticle on the ventral surface just anterior and posterior to the vulva, and by transversely elongate pouches anterior and posterior to the vulva. Both sexes have a constricted area of the stylet shaft just anterior to the knobs, and on the male the intersection of the lateral field and bursa appear sclerotized. 相似文献