Prophylactic effect of selenium dioxide against degeneration (white striation) of muscles in chicks.
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Animals↗
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A serum-free medium for clonal growth and serial subculture of diploid rat liver epithelial cells.
Clonal growth and serial subculture of diploid liver epithelial cells from neonatal rats were achieved in a serum-free medium (SFM) supplemented with linoleic and oleic acid linked to fatty acid-free bovine serum albumin (fafBSA), epidermal growth factor (EGF), transferrin, insulin, selenous acid, and fetuin. Because it is not known whether factors added to defined media facilitate attachment, support proliferation, or both, a serum-free "attachment medium" was first devised in which cells would attach to the substratum without loss of viability. Then a growth medium that would support cell proliferation was developed. Fetuin enhanced the degree of attachment, and the lipid supplements and EGF induced a marked proliferative response. Serum-free medium supported the formation of colonies equivalent in size, number, and morphology to those obtained in serum-supplemented medium. Cells plated at a higher inoculum density and subcultured regularly for up to 25 wk underwent two to three doublings per week and acquired a flattened epithelial cell morphology. Early passages of rat liver epithelial cells, cultured in SFM may be useful in studies of the regulation of cell proliferation and differentiation.
Animals↗
Subcellular distribution of selenium during uptake and its influence on mitochondrial oxidations in germinating Vigna radiata L.
The metabolic significance of Se in plants is not well documented, though the presence of many selenoenzymes in bacteria and the essentiality of Se in higher animals is established. Since germination is an active process in plant growth and metabolism, the effect of Se was investigated in germinating Vigna radiata L, a nonaccumulating Se-deficient legume. Growth and protein were enhanced in seedlings supplemented with selenium (Se) as sodium selenite in the medium up to 1 microgram/mL. The pattern of uptake of 75Se in the differentiating tissues and the subcellular distribution were investigated. The percentage of incorporation of 75Se was greater in the mitochondria at the lowest level (0.5 micrograms/mL) of Se supplementation compared to higher levels of Se exposure. Proteins precipitated from the postmitochondrial supernatant fractions, when separated by means of polyacrylamide gel electrophoresis (PAGE), indicated a major selenoprotein in the seedlings germinated at 2.0 micrograms/mL Se. In seedlings grown with supplemented Se, enhanced respiratory control ratio and succinate dehydrogenase activity were observed in the mitochondria of tissues, indicative of a role for Se in mitochondrial membrane functions.
Cotyledon↗
Cadmium-induced metallothionein in earthworms (Lumbricus terrestris).
Studies are continuing to compare the common earthworm (Lumbricus terrestris) to rodents by their reactions to toxic levels of metals. A recent study suggests that LD50 of selenium compounds were about ten times less in worms than in rodents, but the toxicity of cadmium was of the same order of magnitude between these diverse species. An interesting finding is that the common earthworm produces a Cd-bound protein, metallothionein, after the injection of cadmium salts, and, similar to rodents, two Cd-bound isoproteins can be isolated by a Sephacryl S-200 column and monitored by both atomic absorption and liquid scintillation spectroscopy.
Animals↗
The incorporation of Na2 75SeO3 into sheep erythrocytes.
Injection of Na2 75SeO3 into untreated, phlebotomized, and phenylhydrazine treated sheet has shown that the rate of 75SeO3-incorporation into erythrocytes is dependent on the degree of stimulation. Analysis of labeled erythrocytes by gel filtration and two-dimensional electrophoresis has indicated that the transient labeling of a hemoglobin-like peptide is the only protein labeled in addition to glutathione peroxidase.
Animals↗
Combined effect of mercuric chloride and selenium dioxide on the growth of the cyanobacteria, Anacystis nidulans.
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Cyanobacteria↗
Protective effects of selenium against mercury toxicity in cultured Atlantic spotted dolphin (Stenella plagiodon) renal cells.
Marine mammals are known for their low susceptibility to mercury toxicity, and selenium may play a role in this protection against mercury intoxication. To gain insight into mechanisms by which selenium might inhibit mercury toxicity in cetacean cells, we investigated the effects of sodium selenite on cell proliferation and cell death (including apoptosis, oncosis, and necrosis) of control and mercuric chloride-treated Atlantic spotted dolphin renal cells (Sp1K cells). Concurrent exposure to 80 microM Na2SeO3 provided full protection against the decrease in cell proliferation induced by 20 microM HgCl2. Pretreatment with Na2SeO3 increased the protective effects of selenium administered later in conjunction with mercury, but pretreatment alone did not provide protection against mercury given alone. Furthermore, Na2SeO3 administered after the exposure to HgCl2 did not protect cells. These data suggest that the coexistence of Na2SeO3 and HgCl2 was essential for the protective effects of Na2SeO3 against the toxicity of HgCl2 in Sp1K cells, and may involve selenium-mercury binding. This is supported by the results of an experiment in which earlier premixed mercury and selenium solutions were less cytotoxic than freshly mixed solutions. Furthermore, HgCl2 induced apoptosis in Sp1K cells, as revealed by nuclear specific dye (7-AAD) incorporation and cell flow cytometry, and this was prevented by the concurrent exposure to Na2SeO3. Inhibition of mercury-induced apoptosis in marine mammal cells, provided by selenium, may contribute to the in vivo protection. This study is the first report that addresses the mechanism of mercury-selenium antagonism in cultured cetacean cells at the cellular level.
Animals↗
Oxidation reactions of acetylenic fatty esters with selenium dioxide/tert-butyl hydroperoxide.
Reaction of methyl undec-10-ynoate (1) with selenium dioxide/tert-butyl hydroperoxide (TBHP) in aqueous dioxane gave methyl 9-oxo-undec-10-ynoate (2, 9%) and 9-hydroxy-undec-10-ynoate (3, 60%), while methyl octadec-9-ynoate (4) yielded mixtures of positional isomers of mono-keto (viz. methyl 8-oxo- and 11-oxo-octadec-9-ynoate, 5, 5%), hydroxy-keto (viz. methyl 8-hydroxy-11-oxo- and 11-hydroxy-8-oxo-octadec-9-ynoate, 6, 10%), and dihydroxy (viz. methyl 8,11-dihydroxy-octadec-9-ynoate, 7, 24%) derivatives. Similar treatment of a conjugated diacetylenic fatty ester (methyl octadeca-6,8-diynoate, 8) furnished a mixture of methyl 5-oxo- and 10-oxo-octadeca-6,8-diynoate (9, 12%) and a complex mixture of very polar products. Reaction of methyl octadec-11E-en-9-ynoate (methyl santalbate) (10) with selenium dioxide/TBHP in aqueous dioxane gave exclusively a mixture of regiospecific products, viz. methyl 8-oxo-octadec-11(E)Z-en-9-ynoate (11, 6%) and methyl 8-hydroxy-octadec-11E-en-9-ynoate (12, 70%). The structures of the various products were determined by a combination of spectroscopic and mass spectral analyses.
Fatty Acids↗
Identification of hydrogen selenide and other volatile selenols by derivatization with 1-fluoro-2,4-dinitrobenzene.
A procedure is described for the trapping and identification of hydrogen selenide and methyl selenol ( CH3SeH ). The volatile selenols were generated by reducing selenious acid or dimethyldiselenide with Zn dust and hydrochloric acid under a stream of nitrogen and passing into a trapping solution composed of 50 mM 1-fluoro-2,4-dinitrobenzene plus 83 mM sodium bicarbonate in 67% dimethylformamide:33% water. The selenols react rapidly to form stable dinitrophenyl (DNP) selenoethers that can be extracted into benzene; these are easily identified by TLC, HPLC, or mass spectrometry. Hydrogen selenide is trapped in 90-99% yield, primarily as the di-DNP- monoselenide with a trace of di-DNP- diselenide .
Chromatography, High Pressure Liquid↗
Radioactive-electrophoretic assay of adenosine 5'-triphosphate sulfurylase activity in crude extracts with sulfate or selenate as a substrate.
An assay method for ATP sulfurylase is presented which employs Na2(35)SO4 as a substrate and measures the production of labeled adenosine 5'-phosphosulfate and 3'-phosphoadenosine 5'-phosphosulfate by low-voltage, hanging paper strip electrophoresis. The method is applicable to crude bacterial or mammalian extracts and accurately measures picomole amounts of product(s). Na2(75SeO4 can also be employed as a substrate, if the unstable radioactive product, adenosine 5'-phosphoselenate, is converted to elemental 75Se degrees by inclusion of reduced glutathione in the reaction mixture. The same paper strip electrophoretic technique can then be used to separate 75Se degrees from the radiolabeled substrate. The method also has utility for measuring any direct reduction by crude microbial extracts of radioactive selenate to selenite, independent of ATP sulfurylase.
Adenosine Phosphosulfate↗
A retrograde transport method for mapping zinc-containing fiber systems in the brain.
A method for selectively labeling the CNS neurons that give rise to zinc-containing axonal boutons is described. Focal intracerebral infusions of selenium anions are used to produce a precipitate (presumably ZnSe) in zinc-containing axonal boutons at the injection site, and within 24-48 h, the precipitate is transported to the neurons of origin of those boutons. Silver enhancement is used to render the ZnSe visible in sections prepared for the light or electron microscope. No evidence of retrograde labeling is apparent in neurons that do not contain zinc in their boutons. Thus, the method provides a chemically specific technique for retrograde tracing of zinc-containing pathways in the CNS.
Animals↗
Determination of the relative contributions of the diselenide and selenol forms of ebselen in the mechanism of its glutathione peroxidase-like activity.
The molecular basis of the glutathione peroxidase activity of ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one) was investigated by the use of synthesised, authentic intermediates identical to those formed by the reaction of ebselen with glutathione. The second order rate constants for the reaction of ebselen (0.29 mM-1 min-1), ebselen-glutathione selenosulfide (less than or equal to 0.01 mM-1 min-1), ebselen selenol (2.8 mM-1 min-1) and ebselen diselenide (0.32 mM-1 min-1) with hydrogen peroxide reveal that the selenol is particularly active in this respect. The determination of the relative amounts of ebselen selenol and diselenide under typical peroxidase assay conditions implies that the selenol is the predominant molecular species responsible for the glutathione--(70%)--and dithiothreitol--(96%)--dependent peroxidase activity of ebselen.
Anilides↗
AP-1 DNA-binding activity is inhibited by selenite and selenodiglutathione.
The binding of the transcription factor AP-1 to DNA has been shown to be modulated by redox control mechanisms. Selenite and selenodiglutathione (GS-Se-SG), inhibit mammalian cell growth and are efficient oxidants of reduced thioredoxin and reduced thioredoxin reductase. Here, we report that selenite and GS-Se-SG efficiently inhibited AP-1 DNA-binding in nuclear extracts from 3B6 lymphocytes. A GS-Se-SG concentration of 0.75 microM resulted in 50% inhibition of AP-1 DNA-binding, whereas the same effect was achieved with 7.5 microM selenite. Nuclear extracts prepared from human 3B6 lymphocytes exposed for 4 h to 10 microM selenite showed a 50% reduction of AP-1 binding. These data suggest that selenite and selenodiglutathione inactivate the AP-1 factor and provide a mechanism by which selenium compounds inhibit cell growth.
Amino Acid Sequence↗
[COMPARATIVE STUDY ON THE LABELLING OF MICRO-ORGANISMS WITH SELENIUM-75].
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Bacteriological Techniques↗
Variation of Se, Zn, Co, Fe and Rb distribution in rats upon sequence of injection with SeO2 and glutathione.
The contents of Se, Zn, Co, Fe and Rb in several organs of Wistar rats were determined by instrumental neutron activation analysis (INAA) after injections of SeO2 and glutathione (GSH). Se was incorporated in all the examined organs, and the efficiency of incorporation does not depend upon the sequence of injection with SeO2 and GSH. The sequence of these injections affects the contents of the other elements in all the examined organs.
Animals↗
Selenium dioxide oxidation of vitamin D3 acetate to a dimer of 1-oxotransvitamin D3 acetate.
The treatment of vitamin D3 acetate with selenium dioxide and t-butyl hydroperoxide leads to a mixture from which a Diels-Alder dimer of 1-oxotransvitamin D3 acetate was isolated.
Cholecalciferol↗
Hydrogen selenide and methylselenol.
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Chromatography, High Pressure Liquid↗
The effects of dietary L-ascorbic acid on the absorption and utilization of Na75SeO3 of silver-treated rats.
Male hooded lister rats of the Rowett Institute strain, treated with silver in the drinking water, were used to study the effects of L-ascorbic acid on the utilization of Na75SeO3. Silver treatment dramatically decreased the absorption of 75Se from the rat GI tract. An attempt was made to utilize the reducing ability of L-ascorbic acid upon the absorption of 75Se from the rat GI tract. Increasing concentrations of L-ascorbic acid slightly increased the amount of 75Se absorbed from the rat gut.
Animals↗