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51.
Summary A model system of polyacrylamide films containing the Triton extract of rat brain homogenate was applied to investigate quantitatively some aspects of three methods for the cytochemical demonstration of acetylcholinesterase activity (Lewis 1961; Karnovsky and Roots 1964; Tsuji 1974).Biochemical determinations showed that about 90% of the acetylcholinesterase activity originally present in the Triton extract were still detectable in the films. The relationship of the formation of cuprous thiocholine iodide in the case of the methods of Lewis (1961) or Tsuji (1974) and of cupric ferrocyanide at the reaction of Karnovsky and Roots (1964) to either enzyme concentration or incubation time were tested in detail. The results showed that for the method of Tsuji and, with some restrictions, also for the method of Karnovsky and Roots a linearity exists in these two respects. In the case of the Lewis technique, an approximate linearity between the amount of reaction product and incubation time could only be found from 90 min onward, but no linearity was detected in relation to the enzyme concentration. At low enzyme concentrations, too little white precipitate was formed in comparison to higher ones. Therefore it is suggested that this technique, as compared to the methods of Tsuji and Karnovsky and Roots, probably is less suitable as a quantitative cytochemical method.This word was performed while one of us (Dr. Andrä) was in receipt of a visitor grant from the Netherlands Organization for the Advancement of Pure Research (ZWO)  相似文献   
52.
J Andr?  Z Lojda 《Histochemistry》1986,84(4-6):575-579
The "direct coloring" thiocholine method of Karnovsky and Roots (1964) for the demonstration of acetylcholinesterase (AChE) activity was modified and adapted to the technique of semipermeable membranes. In this way it is possible to demonstrate histochemically both the bound as well as the soluble part of AChE activity. The localization of the reaction product is very distinct. Microdensitometric investigations of results of this method showed a linear increase of the amount of reaction product up to an incubation time of 180 min and section thickness up to 24 micron. The medium supplemented with buffer (instead of agar) can be used for the demonstration of AChE activity in cryostat sections adherent to slides and is also very suitable for the detection of multiple forms of AChE in polyacrylamide or agarose gels.  相似文献   
53.
Summary The dopaminergic innervation of the goldfish pituitary gland was studied by immunocytochemistry at the electron-microscope level using highly specific antibodies against dopamine coupled to bovine serum albumin with glutaraldehyde. A satisfactory preservation of the tissue was achieved after immersion in 5% glutaraldehyde in phosphate buffer containing sodium metabisulfite to prevent oxidation of the endogenous dopamine. The immunocyto-chemical procedure was performed on Vibratome sections using the preembedding method. Immunoreactivity was restricted to part of the neurosecretory type-B fibers (diameter of the secretory vesicles lower than 100 nm) in which it was found to occupy the whole cytoplasm. Labeled fibers were observed within the neurohypophysis in the different parts of the gland and in the adenohypophyseal tissue where immunoreactive profiles were detected in close apposition to the different cell types. These data are in agreement with previous results obtained by means of radioautography and further support a role for dopamine in the neuroendocrine regulation of pituitary functions in teleosts.  相似文献   
54.
Ethanol-sensitive mutants of Saccharomyces cerevisiae   总被引:3,自引:0,他引:3  
Saccharomyces cerevisiae mutants unable to grow at ethanol concentrations at which the wild type strain S288C does grow, have been isolated. Some of them show additional phenotypic alterations in colony size, temperature sensitivity and viability in ethanol, which cosegregate with the growth sensitivity in ethanol. 21 selected monogenic ethanol-sensitive mutants define 20 complementation groups, denominated ETA1 to ETA20, which indicates that there is a high number of genes involved in the ethanol tolerance/sensitivity mechanism.Out of 21 selected monogenic mutants, 20 are not altered in the glycolytic pathway since, when maintained in glucosesupplemented medium, they can produce as much ethanol as the wild type and at about the same velocity. Nor do any of the mutants seem to be altered in the lipid biosynthetic pathway since, whether grown in the absence or in the presence of ethanol, their concentration of fatty acids and ergosterol is similar to that of the wild type under the same conditions. Therefore growth sensitivity to ethanol does not seem necessarily to be related to carbohydrate or lipid metabolism.Non-common abbreviations YP yeast extract peptone medium - YPD yeast extract peptone dextrose agar or medium - YPG yeast extract peptone glycerol agar - YPDE yeast extract peptone dextrose ethanol agar or medium - SD yeast nitrogen base dextrose agar - SPO yeast extract potassium acetate glucose agar - PD parental ditype - NPD non-parental ditype - TT tetratype  相似文献   
55.
Clathrin-associated proteins contain bound nucleotide   总被引:2,自引:0,他引:2  
An alcohol dehydrogenase isolated from Zymomonas mobilis was found to be activated by ferrous ions but not by zinc, after inactivation with metal-complexing agents. Cobaltous ions also re-activated to a lesser extent. It is suggested that in this species the alcohol dehydrogenase naturally contains iron. Kinetic studies on the iron-treated enzyme indicate an 'alcohol activation' phenomenon, which may have physiological relevance in overcoming product inhibition during fermentation.  相似文献   
56.
The oxidation-reduction potentials of the two c-type hemes of Pseudomonas aeruginosa cytochrome c peroxidase (ferrocytochrome c:hydrogen-peroxide oxidoreductase EC 1.11.1.5) have been determined and found to be widely different, about +320 and -330 mV, respectively. The EPR spectrum at temperatures below 77 K reveals only low-spin signals (gz 3.24 and 2.93), whereas optical spectra at room temperature indicate the presence of one high-spin and one low-spin heme in the enzyme. Optical absorption spectra of both resting and half-reduced enzyme at 77 K lack features of a high-spin compound. It is concluded that the heme ligand arrangement changes on cooling from 298 to 77 K with a concomitant change in the spin state. The active form of the peroxidase is the half-reduced enzyme, in which one heme is in the ferrous and the other in the ferric state (low-spin below 77 K with gz 2.84). Reaction of the half-reduced enzyme with hydrogen peroxide forms Compound I with the hemes predominantly in the ferric (gz 3.15) and the ferryl states. Compound I has a half-life of several seconds and is converted into Compound II apparently having a ferric-ferric structure, characterized by an EPR peak at g 3.6 with unusual temperature and relaxation behavior. Rapid-freeze experiments showed that Compound II is formed in a one-electron reduction of Compound I. The rates of formation of both compounds are consistent with the notion that they are involved in the catalytic cycle.  相似文献   
57.
The Na+ channel activity (tetrodotoxin sensitive 22Na+ flux induced by veratridine and/or anemone toxin II) was studied in two fractions of brain cell plasma membranes, named A and B, isolated by the method of Gray and Whittaker ((1962) J. Anat. 96, 79–87) from rats 5, 10, 30 and 60 days old. The 22Na+ flux was measured in membrane vesicles formed by the isolated membranes, in the absence of drugs (control), in the presence of veratridine, and in the presence of veratridine plus tetrodotoxin. Fraction A consists primarily of neuronal and glial membranes in rats of 5 and 10 days of age, while in the older rats this fraction becomes enriched in myelin. In Fraction A of 5-day-old and 10-day-old rats, veratridine (25 μM) increases the 22Na+ flux 2.4- and 1.6-fold, respectively, and the increment continues to diminish with age, until it becomes negligible in the 60-day-old rats. Fraction B consists of synaptosomes and membrane vesicles, and at the four ages studied veratridine (25 μM) causes an increment of the 22Na+ flux of about 2.5-fold. Fractions A and B from 10-day-old rats, and Fraction B from 60-day-old rats, which are sensitive to veratridine, also respond to anemone toxin II. When veratridine is used in presence of anemone toxin II (0.5 μM), the K0.5 for veratridine is diminished and the maximum 22Na+ flux is increased. The increments of 22Na+ flux caused by veratridine and/or anemone toxin II in Fractions A and B are blocked by tetrodotoxin (K0.5 approx. 5 nM). Fraction A from 60-day-old rats could be subfractionated by osmotic shock and sucrose gradient centrifugation to obtain three subfractions, two of which are enriched in axolemma and display Na+ chennel activity. The other subfraction is enriched in myelin and shows no Na+ channel actiivty. The plasma membrane preparations from young rats (up to 10 days) are devoid of myelin and are useful for studies of Na+ channel activity.  相似文献   
58.
59.
The immunogenicity and reactogenicity of the Urabe Am 9 mumps virus vaccine strain were studied after the administration of different doses of the vaccine to 197 children ranging in age from seven and a half months to nine years and without a history of mumps. There was no effect of dose on the response in serum neutralizing antibodies in the range of 10(2.9) to 10(4.7) TCID50/dose. In the 90 subjects without detectable serum neutralization antibodies before vaccination seroconversion was obtained in 94.4% after 42 days. Half of a group of 34 seropositive children who were tested also showed a fourfold or greater rise in antibodies. Persistence of vaccine-enhanced haemagluttinin-inhibition (EHI) antibodies was satisfactory as only two of 46 vaccinees followed-up for between 27 and 32 months had undetectable levels of EHI antibodies and the geometric mean titre of vaccine-induced EHI antibodies had only fallen to about one-third by 32 months after vaccination. Although there was serological evidence of a subclinical re-infection in three subjects, to date none of the vaccinees has had clinical mumps indicating that the vaccine confers protection against disease. The vaccine was well tolerated. Furthermore, the majority of the few 'reactions' reported were probably not vaccine-related. It is concluded that the Urabe Am 9 is an acceptable strain for use in live mumps vaccines.  相似文献   
60.
Summary The apical cell coat of the olfactory epithelium proper and the vomeronasal neuroepithelium of the rat was investigated electronmicroscopically by means of the Ruthenium-red reaction. In the olfactory epithelium proper, the cilia of receptor cells and microvilli of supporting cells possess a cell coat measuring approximately 10 nm in thickness. In the vomeronasal neuroepithelium, the apical cell coat is thicker than in the olfactory epithelium proper. On microvilli of vomeronasal receptor cells the cell coat varies in thickness from 15 to 20 nm, and on microvilli of supporting cells it measures approximately 75 nm. The functional implications of these findings are discussed.A portion of this study was presented at the 6th European Anatomical Congress in Hamburg. This publication is dedicated to Prof. E. KlikaSupported by the Deutsche Forschungsgemeinschaft (Br 358/5-1).  相似文献   
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