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101.
L B Nguyen J F Gregory J J Cerda 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1983,173(4):568-573
Previous research has indicated that dietary fiber may affect the absorption and utilization of certain nutrients. To determine the effect of certain fiber materials on the absorption of B-6 vitamers, jejunal segments from young male adult rats were perfused in situ with a control solution containing 0.02 mM pyridoxine (PN), 0.02 mM pyridoxal (PL), and 0.02 mM pyridoxamine (PM), followed by a test solution containing the same vitamin B-6 mixture and one of five fiber-rich test materials (cellulose, pectin, lignin, homogenized fresh carrot, or carrot homogenized after 10 min boiling) added at a concentration of 1-3%. The mean absorption rates of PL, PN, and PM from the control solution were, respectively, 3.66 +/- 0.23, 2.06 +/- 0.23, and 1.74 +/- 0.37 nmole/min/20 cm jejunal segment. There were no significant differences between the absorption rates of B-6 vitamers from control and test solutions containing cellulose, pectin, and lignin. The absorption rates of PM and PL were significantly depressed (P less than 0.05 and P less than 0.01, respectively) by the presence of fresh or cooked carrot. The absorption rate of PN in presence of cooked carrot was also decreased relative to the control value but the difference was only marginally significant (P less than 0.10). When the concentration of fresh carrot in the test solution was increased to 10% by weight and the perfusion rate was decreased from 1.91 to 0.49 ml/min in a second perfusion experiment, there was a significant increase in variability and the differences between absorption rates of the B-6 vitamers in control and test solutions were not statistically significant. The limited evidence of adverse effect of carrot on absorption of vitamin B-6 suggested the need for further clarification of the influence of dietary fiber in an unrefined state on the bioavailability of vitamin B-6. 相似文献
102.
Gregory A. Osenga Bruce C. Coull 《Journal of experimental marine biology and ecology》1983,67(3):221-225
Meiofauna were collected from adjacent areas with and without Spartina alterniflora Loisel culms. Environmental complexity resulting from root structure cannot be determined by simply observing S. alterniflora culm distribution. There were no significant differences between the two areas with respect to root density or root sizes; however, the number of live roots was significantly higher in the area containing Spartina culms. Nematodes, the most abundant taxon were positively correlated with live root density. In contrast, the number of dead roots and harpacticoid copepods were higher in the area without culms. This study suggests that nematodes are positively associated with micro-oxygenated zones produced by live S. alterniflora roots. Other measures of biogenic structure, such as total root density or root size fractions are not important in affecting nematode abundance. 相似文献
103.
104.
Specific Inhibition of the Cyanide-insensitive Respiratory Pathway in Plant Mitochondria by Hydroxamic Acids 总被引:77,自引:44,他引:33
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Gregory R. Schonbaum Walter D. Bonner Jr. Bayard T. Storey James T. Bahr 《Plant physiology》1971,47(1):124-128
Hydroxamic acids, R-CONHOH, are inhibitors specific to the respiratory pathway through the alternate, cyanide-insensitive terminal oxidase of plant mitochondria. The nature of the R group in these compounds affects the concentration at which the hydroxamic acids are effective, but it appears that all hydroxamic acids inhibit if high enough concentrations are used. The benzhydroxamic acids are effective at relatively low concentrations; of these, the most effective are m-chlorobenzhydroxamic acid and m-iodobenzhydroxamic acid. The concentrations required for half-maximal inhibition of the alternate oxidase pathway in mung bean (Phaseolus aureus) mitochondria are 0.03 mm for m-chlorobenzhydroxamic acid and 0.02 mm for m-iodobenzhydroxamic acid. With skunk cabbage (Symplocarpus foetidus) mitochondria, the required concentrations are 0.16 for m-chlorobenzhydroxamic acid and 0.05 for m-iodobenzhydroxamic acid. At concentrations which inhibit completely the alternate oxidase pathway, these two compounds have no discernible effect on either the respiratory pathway through cytochrome oxidase, or on the energy coupling reactions of these mitochondria. These inhibitors make it possible to isolate the two respiratory pathways and study their mode of action separately. These inhibitors also enhance an electron paramagnetic resonance signal near g = 2 in anaerobic, submitochondrial particles from skunk cabbage, which appears to be specific to the alternate oxidase and thus provides a means for its assay. 相似文献
105.
Changes in Ribonucleic Acid Fractions During Maturation of Mimosa Epicotyl Tissues 总被引:1,自引:1,他引:0
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Gregory N. Brown 《Plant physiology》1969,44(2):272-276
Total RNA and DNA of mimosa epicotyl tissues were extracted and the RNA fractionated into specific soluble RNAs (sRNAs) at different times during late germination. Epicotyls collected at each time contained qualitatively comparable meristematic and developing tissues, while mature tissues increased. Quantitative ratios of total RNA to DNA and total sRNAs to approximated ribosomal RNA (rRNA) varied consistently during development. Terminal nucleosides of sRNA did not vary in any consistent pattern through development. On the other hand, regular changes in quantitative ratios of specific sRNA groups were observed during development. 相似文献
106.
T. G. Amos 《Entomologia Experimentalis et Applicata》1967,10(1):1-6
The humidity reactions of intact and antennaless specimens of Carpophilus dimidiatus and C. hemipterus were studied. The results suggested that the hygroreceptors mediating a response to high humidities are situated on the antennae in both species and those mediating a response to low humidities, in the case of C. dimidiatus, elsewhere on the body.
On transfer from tropical Stored Products Centre, O.D.M., Slough, Bucks 相似文献
Résumé On a étudié la réaction à l'humidité de Carpophilus hemipterus et C. dimidiatus intacts et sans antennes. Les résultats suggèrent que les hygrorécepteurs qui répondent aux humidités élevées se trouvent sur l'antenne dans les deux espèces et ceux qui répondent aux basses humidités sur l'antenne de C. hemipterus et dans une autre partie du corps de C. dimidiatus.
On transfer from tropical Stored Products Centre, O.D.M., Slough, Bucks 相似文献
107.
By gentle sonic treatment, Escherichia coli cells were modified to permit penetration of actinomycin D, adenosine triphosphate, trypsin, ribonuclease, and polyuridylic acid. The behavior of these "soniplasts" as protein-synthesizing particles was investigated. 相似文献
108.
Separation of the antihemophilic factor (F. 8) from fibrinogen with thrombin and manganese chloride 总被引:2,自引:0,他引:2
109.
Cellular evolution in induced inflammation in uremic patients 总被引:2,自引:0,他引:2
110.