scholarly journals Some fluorescent counterstains for neuroanatomical studies.

1982 ◽  
Vol 30 (2) ◽  
pp. 123-128 ◽  
Author(s):  
L C Schmued ◽  
L W Swanson ◽  
P E Sawchenko
Keyword(s):  
Ultraviolet Light ◽  
Ethidium Bromide ◽  
Green Light ◽  
Neural Tissue ◽  
Neutral Red ◽  
Retrograde Tracer ◽  
Fluorescent Markers ◽  
Cell Counts ◽  
Low Concentrations ◽  
Nissl Stain

Methods for counterstaining neural tissue that contains fluorescent markers have been developed. Acridine orange is useful for localizing cells that are retrogradely labelled with the fluorescent tracers true blue, bisbenzimide, and nuclear yellow because at low concentrations it yields a green Nissl stain when excited with blue, but not with ultraviolet, light; since the tracers fluoresce only when exposed to ultraviolet light, they are not masked by the counterstain. In addition, counterstaining at pH 2 increases bisbenzimide fluorescence considerably. Ethidium bromide is useful for immunohistochemistry (IHC) because it yields a bright red Nissl counterstain when excited by green light, and is only faintly visible when the fluorescein marker is excited with blue light, or when ultraviolet excitation is used. Ethidium bromide is therefore a good counterstain for fluorescent retrograde tracer and for combined IHC-retrograde tracer studies as well. Certain dyes are also useful for studies of the normal morphology of neural tissue. For example, bisbenzimide and nuclear yellow at low concentrations produce a brilliant Nissl stain at pH 2, and stain only nuclei at pH 7.2. The latter procedure may be particularly useful for cell counts. Finally, neutral red, astrazone red, and safranin-O differentially stain cells amd myelinated fibers, producing fluorescence analogs of the Klüver-Barrera stain.

Concentrations of Endotoxins in Waters Around the Island of Montreal, and Treatment Options

2008 ◽  
Vol 43 (4) ◽  
pp. 291-303 ◽  
Author(s):  
Ronald Gehr ◽  
Santiago Parent Uribe ◽  
Isabel Fatima Da Silva Baptista ◽  
Bruce Mazer
Keyword(s):  
Ultraviolet Light ◽  
Contact Time ◽  
Treatment Options ◽  
Test Methods ◽  
Water Disinfection ◽  
Gram Negative Bacteria ◽  
Limulus Amebocyte Lysate ◽  
Low Concentrations ◽  
Drinking Water Disinfection ◽  
Factor C

Abstract Endotoxins are a component of most Gram negative bacteria, and some cyanobacteria. They may be toxic to humans when inhaled or injected, but the effects are unclear when they are ingested. In fact, low concentrations may protect children against certain allergies. Data for endotoxins in Quebec waters are unavailable, hence this study mapped levels in the waters around Montreal, using two commercial test methods. The recently developed factor C method had a greater linear range and was more convenient to use than the widely used Limulus amebocyte lysate (LAL) method. Although the methods gave endotoxin values of the same order, a consistent relationship between the two could not be established. Endotoxin concentrations in the untreated waters varied from 32 to 1,188 EU/mL, comparable in the literature from pristine waters to wastewaters. Values were generally lower in the summer. Filtration is known to be partially effective at removing endotoxins, but the effects of disinfection are not well established. Accordingly, chlorination, ozonation, and ultraviolet light were tested for the destruction of endotoxins in water, at doses found during drinking water disinfection. While chlorine and ultraviolet light had minimal effects on endotoxin levels, ozone could achieve up to 60% reductions at Ct values (concentration x contact time) as low as 2.5 mg•min/L.

Regulation of Anthocyanin Synthesis in Apple Skin. I. Comparison of the Effects of Cycloheximide, Ultraviolet Light, Wounding and Maturity

1977 ◽  
Vol 4 (1) ◽  
pp. 111 ◽  
Author(s):  
DJ Chalmers ◽  
JD Faragher
Keyword(s):  
Ultraviolet Light ◽  
Specific Treatment ◽  
Primary Effect ◽  
Anthocyanin Synthesis ◽  
Secondary Effect ◽  
Anthocyanin Accumulation ◽  
Fruit Tissue ◽  
Anthocyanin Formation ◽  
Low Concentrations ◽  
Fruit Maturity

Cycloheximide applied to apple skin discs inhibited anthocyanin synthesis even at very low concentrations (0.01 �g ml-1) but stimulated accumulation in whole apple skin at concentrations between 0.05 and 30 �g ml-1. When cycloheximide was applied as a drop to whole fruit, anthocyanin synthesis was inhibited in the zone of application. A region of enhanced synthesis surrounded the inhibited area when the concentration was 1 �g ml-1 or higher. Inhibition appears to be the primary effect, while stimulation is a secondary effect of the application of cycloheximide. Similarly, exposure to u.v. light for 5-60 min promoted anthocyanin accumulation. Wounding of fruit tissue, as a specific treatment or while preparing skin discs, increased the level of anthocyanin in the skin and replaced the stimulating effect on anthocyanin formation of applied u.v. light or cycloheximide. The effects of wounding and cycloheximide decreased with increasing fruit maturity. The data suggested that wounding, u.v. light, maturity and cycloheximide act through a common effector, perhaps ethylene.

scholarly journals MITOCHONDRIAL PROTEIN SYNTHESIS IN HELA CELLS

1974 ◽  
Vol 60 (3) ◽  
pp. 755-763 ◽  
Author(s):  
Jonas B. Galper
Keyword(s):  
Protein Synthesis ◽  
Ethidium Bromide ◽  
Mitochondrial Protein ◽  
Specific Protein ◽  
Mitochondrial Proteins ◽  
Mitochondrial Protein Synthesis ◽  
Initiator Trna ◽  
Low Concentrations ◽  
Separate Protein

HeLa cell mitochondrial proteins have been shown to be the products of two separate protein-synthesizing systems; one, the general cellular mechanism, sensitive to inhibition by cycloheximide, the other, a specific mitochondrial system subject to inhibition by low concentrations of chloramphenicol (Galper, J. B., and J. E. Darnell. 1971. J. Mol. Biol 57:363). Preliminary data have suggested that a mitochondrial N-formyl-methionyl-tRNA (f-Met-tRNA) might be the initiator tRNA in the latter (Galper, J. B., and J. E. Darnell. 1969. Biochem. Biophys. Res. Commun. 34:205; 1971. J. Mol. Biol. 57:363). It is demonstrated here that the synthesis of these endogenous mitochondrial proteins is also subject to inhibition by ethidium bromide and decays with a half-life of 1½–2 h in cultures incubated with low concentrations of this dye. The role of formylated f-Met-tRNA as the initiator tRNA in the synthesis of mitochondrial proteins is supported by data from several experiments. The rates of ethidium bromide inhibition of both the charging of f-Met-tRNA and of the synthesis of mitochondrial proteins are strikingly similar. Inhibition by aminopterin of the formylation of f-Met-tRNA greatly depresses the rate of mitochondrial-specific protein synthesis. In the absence of the synthesis of these proteins, respiration, the levels of cytochromes a–a3 and b, and the number of mitochondrial cristae are decreased. The implications of these findings as they relate to mitochondrial biogenesis are discussed.

Neutral Red Fluorescence of Chromatin: Specificity and Binding Mechanism

1982 ◽  
Vol 37 (1-2) ◽  
pp. 139-141 ◽  
Author(s):  
Roberto H. Espelosin ◽  
Juan C. Stockert
Keyword(s):  
Nucleic Acid ◽  
Fluorescence Intensity ◽  
Dna Content ◽  
Neutral Red ◽  
Binding Mechanism ◽  
Inorganic Cations ◽  
Red Fluorescence ◽  
Low Concentrations ◽  
Chicken Erythrocytes ◽  
Chromatin Fluorescence

Abstract Neutral Red, Chromatin Fluorescence, Nucleic Acid Cytochemistry, Intercalative Binding to DNA After treatment with neutral red at low concentrations (10-6, 10-5 m), the chromatin o f chicken erythrocytes shows an intensive red fluorescence, which is reduced or prac­ tically abolished when nuclei become stained by using the dye at concentrations higher than 10~* M. Both the fluores­ cence and staining reactions are dependent on the DNA content of chromatin. Neutral red fluorescence o f nuclei increases considerably after treatment with inorganic cations (Al3+, Ba2+), while previous treatments with meth­ ylene blue reduce the fluorescence intensity. The possi­ bility that chromatin fluorescence depends on the inter­ calative binding of neutral red is suggested.

Toxicity, Analysis, and Production of Aspergillic Acid and its Analogues

1973 ◽  
Vol 51 (9) ◽  
pp. 1311-1315 ◽  
Author(s):  
J. C. MacDonald
Keyword(s):  
Ultraviolet Light ◽  
Aspergillus Flavus ◽  
Yeast Extract ◽  
Separate Study ◽  
Differential Analysis ◽  
Liquid Media ◽  
Low Concentrations ◽  
Toxicity Analysis

A differential analysis, utilizing the decomposition of 3,6-disubstituted-1-hydroxy-2(1H) pyrazinones (HPYs) by ultraviolet light, was developed to measure low concentrations of total HPYs (aspergillic acid and/or its analogues) in cultures.Two strains of Aspergillus flavus were found to differ in their ability to produce aflatoxins and HPYs on liquid media composed of 2% yeast extract and varying amounts of sucrose. Production of HPYs by both strains was best in the absence of sucrose and production of aflatoxins was best on media containing 10–20% sucrose. The better producer of HPYs was strain PRL 932, but when it was grown on moist seeds of peas, barley, maize, or wheat, it produced only traces of these compounds.In a separate study, two analogues of aspergillic acid were tested for toxicity in mice. The toxicity of a novel analogue, 3-(2-(methylthio)-ethyl)-6-sec-butyl-1-hydroxy-2(1H) pyrazinone, was the same as that of a more common analogue, neoaspergillic acid.

scholarly journals THE EFFECT OF ETHIDIUM BROMIDE ON MITOCHONDRIAL DNA SYNTHESIS AND MITOCHONDRIAL DNA STRUCTURE IN HELA CELLS

1971 ◽  
Vol 51 (1) ◽  
pp. 116-122 ◽  
Author(s):  
Robert D. Leibowitz
Keyword(s):  
Mitochondrial Dna ◽  
Dna Synthesis ◽  
Ethidium Bromide ◽  
Hela Cells ◽  
Buoyant Density ◽  
Dna Structure ◽  
Low Concentrations ◽  
Mitochondrial Dna Synthesis

The synthesis of mitochondrial DNA (mDNA) in HeLa cells is selectively inhibited by relatively low concentrations of ethidium bromide. After exposure of cells to strongly inhibitory concentrations of the drug, the apparent superhelix density of mDNA is rapidly increased, as judged by its buoyant density in CsCl in the presence of ethidium bromide. Mitochondrial DNA synthesized in the presence of partially inhibitory concentrations of ethidium bromide is also altered in its buoyant density in the presence of the dye, but is more heterogeneous in this respect. However, the change in buoyant density of newly synthesized mDNA may be explained by changes in structure other than a change in superhelix density, as indicated by its increased resistance to digestion by pancreatic DNase.

scholarly journals PROTEIN DEGRADATION IN CULTURED CELLS

1974 ◽  
Vol 63 (2) ◽  
pp. 430-440 ◽  
Author(s):  
Maurice Wibo ◽  
Brian Poole
Keyword(s):  
Protein Degradation ◽  
Cathepsin D ◽  
Cultured Cells ◽  
Neutral Red ◽  
Cellular Proteins ◽  
Equilibrium Density ◽  
Turnover Rates ◽  
Low Concentrations ◽  
Slow Turnover

The degradation of cellular proteins in fibroblasts, both those of rapid and those of slow turnover rates, was inhibited by low concentrations of chloroquine or neutral red in the medium. Cells inhibited by chloroquine can be inhibited further by fluoride. Chloroquine was taken up by the fibroblasts and the concentration in the cells reached several hundred times that in the medium. Isopycnic fractionation studies showed that within the cells the chloroquine was concentrated in the lysosomes, and that these chloroquine-containing lysosomes had a lower equilibrium density than the lysosomes of untreated cells. Chloroquine, at concentrations attained inside the lysosomes, inhibited cathepsin B1 but not cathepsin D. It is concluded that chloroquine impairs the breakdown of cellular proteins after these have entered the lysosome system, probably through inhibition of cathepsin B1.

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