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991.
Detection of impervious tissue in tree bark with selective histochemistry and fluorescence microscopy 总被引:2,自引:0,他引:2
A R Biggs 《Stain technology》1985,60(5):299-304
Use of conventional histochemical tests in conjunction with fluorescence microscopy has validated the concept of impervious tissue in the bark of trees. Application of phloroglucinol + HCl or toluidine blue O selectively quenched lignin autofluorescence and allowed visualization of intracellular suberin lamellae previously undetected. Fluorescence of intracellular lamellae was quenched with Sudan black B and enhanced with Sudan IV thus providing evidence for the suberized nature of a tissue heretofore regarded as nonsuberized. 相似文献
992.
Androst-4-en-3-one analogs incorporating a trimethylsilyl or a trimethylsilylmethyl group at C-1, C-2 or C-19 were prepared and evaluated as inhibitors of aromatase. Only 10-[1-hydroxy-2-(trimethylsilyl)ethyl]estr-4-ene-3,17-dione inhibited human placental aromatase. Enzyme kinetic analysis revealed competitive inhibition [apparent dissociation constant (Ki) of 562 +/- 12 nM] associated with marginal time-dependent inhibition. 相似文献
993.
The efficacy of radioimmunoassay (RIA) for the measurement of estradiol-17 beta (E2) in murine plasma was investigated. When Sephadex LH-20 or celite column chromatography was used to separate E2 from estrone (E1) and other cross-reacting compounds, the results were erratic if small volumes of mouse plasma were resolved. Assay of a diethyl ether extract of plasma (500 microL) was the most practical method for estimating the concentration of estradiol-17 beta in mice. This method was used to determine the pattern of estrogen secretion during the estrous cycle, on the day of implantation and during pregnancy. No convincing change in estrogen secretion was observed in the diestrous/proestrous mouse. By comparison, estrogen levels were elevated during pregnancy. Taken together, these results implied that cross-reactive components in plasma masked low levels of endogenous estrogen. Further evaluation of mouse plasma and urine using a co-chromatography technique to examine estrogen elution from a reverse-phase HPLC system followed by GC/MS analysis indicated the presence of equol [7-hydroxy-3-(4-hydroxyphenyl)chroman], a phytoestrogen metabolite with a ring structure similar to estradiol-17 beta. Equol and possibly other cross-reactive components of plasma may account for the apparent lack of increased estrogen secretion during the mouse estrous cycle and on the day of implantation as determined by the radioimmunoassay of ether extracts of plasma. 相似文献
994.
The amino acid sequence of equine milk lysozyme 总被引:2,自引:0,他引:2
The amino acid sequence of equine milk lysozyme has been elucidated. The study involves the determination of the sequence of the N-terminal region of the whole protein, cyanogen bromide fragments, tryptic and chymotryptic peptides and fragments produced by chemical cleavage after tryptophan residues. The protein consists of a single chain of 129 amino acid residues and has a Mr of 14647. While equine milk lysozyme has the essential features of a c(chick)-type lysozyme, there is only 51% sequence homology with human milk lysozyme and 50% with domestic hen egg white lysozyme. Some of the implications of the large number of differences are discussed. 相似文献
995.
996.
We have examined the redox behavior of the cytochrome c1aa3 complex from Thermus thermophilus. In potentiometric titrations the cytochrome c behaves as an independent center having n = 1 and E = 205 mV (NHE). Under the assumption that the individual centers equilibrate independently in this experiment, changes in the absorption band at 603 nm have been resolved into two components: cytochrome a (n = 1, Em = 270 mV, 60% spectral contribution) and cytochrome a3 (n = 2, Em = 360 mV, 40% spectral contribution). The n = 2 process was attributed to strong chemical coupling between cytochrome a3 and CuB. The enzyme was also titrated with a mixture of NADH and PMS, and the results are shown not to conform to a model of intramolecular equilibrium according to the equilibrium constants obtained from the potentiometric titration. It is suggested that a conformational equilibrium within the complex may control electron transfer between cytochromes a and a3. 相似文献
997.
Thorling E. B. Overvad K. Heerfordt A. Foldspang A. 《Biological trace element research》1985,8(1):65-73
Biological Trace Element Research - Serum selenium concentration was determined over a full year in healthy donors from the Blood Bank at the municipal Hospital in Aarhus, Denmark. The age range of... 相似文献
998.
Because of the low safety factor estimated for the normal content of Cd in human foods, it is important to establish the influence of food constituents such as phytate on the bioavailability of this toxic metal. We studied the retention of radioactive109Cd administered to rats as a chloride or a phytate in a single dose by stomach tube. The animals were fed either a normal rat chow containing 0.29% of phytate or a low phytate diet containing less than 0.1% phytate. Highly elevated levels of109Cd were found only in the animals that were supplied with109Cd as a chloride and had been fed the low phytate diet. In the animals supplied with109Cd as a phytate, which had also received the low phytate diet, the levels of109Cd in the intestine were as high as those in the group mentioned before, but the retentions in all other tissues resembled those of the respective groups fed the normal chow. The findings indicate that phytate is responsible for a considerable decrease in the intestinal absorption of Cd. Furthermore, it appears to exert an influence on the kinetics of Cd retention in the intestine. 相似文献
999.
Rodney A. Bray 《Systematic parasitology》1985,7(1):75-80
Summary A new species, Macvicaria taksengi (Opecoelidae: Plagioporinae), is described from the fishes Otolithes ruber and Sillago sihama from Pinang, Malaysia. It differs from most other members of the genus in the position of the ovary relative to the testes
and the anterior position of the genital pore. A brief discussion on the Indo-West Pacific forms of the genus Macvicaria and related genera includes references to several new combinations: M. [Lebouria] isaitschikowi (Layman, 1930), M. [Plagioporus] sillagonis (Yamaguti, 1938), M. [Plagioporus] chrysophrys (Nagaty & Abdel Aal, 1969) and M. [Plagioporus (Plagioporus)] longisaccus (Fischthal & Kuntz, 1964). 相似文献
1000.
J. A. McComb 《Plant Cell, Tissue and Organ Culture》1985,4(2):151-158
The number of plants in the gazetted rare species Stylidium coroniforme was increased through micropropagation. A method was first developed using the common species S. brunonianum. It was found that for both species, rapid propagation could be obtained by excising shoots from sterile seedlings and inducing shoot proliferation on Murashige and Skoog medium supplemented with 1 M BAP. Rooting was achieved using 1 M IBA and over 100 plants of each species were successfully established in soil. Leaf pieces could also be used to initiate cultures. In media with 20–25 M BAP and 1–5 M IBA, leaf pieces of S. brunonianum, S. piliferum, S. caricifolium and S. crassifolium produced adventitious buds, thus providing another method of micropropagation. 相似文献