Selenium-mediated biochemical changes in Japanese quails : Tissue uptake and distribution of injected(75)selenium labeled sodium selenite in relation to dietary selenium status.
TL;DR: The tissue uptake and distribution of injected [75Se]-sodium selenite as a variance with time and as influenced by dietary selenium status was followed in the tissues of Japanese quails.
Abstract: The tissue uptake and distribution of injected [(75)Se]-sodium selenite as a variance with time and as influenced by dietary selenium status was followed in the tissues of Japanese quails,Coturnix coturnix japonica. Quails maintained on a low selenium semipurified (basal) diet and basal diets supplemented with 0.2 and 2.0 ppm selenium as sodium selenite were injected intraperitonially with(75)Se as sodium selenite (2.8 microcuries). The injected(75)Se was monitored in blood, liver, kidney, heart, and testis at 24, 72, and 144 h after injection. Maximal uptake of the injected(75)Se was observed in tissues of quails maintained on basal diet. The uptake of(75)Se in tissues in general was determined by the dietary Se status. Among the organs studied, kidney had the maximal level of(75)Se, 0.2 ppm (μg/g wet tissue) followed by liver, testis, and heart, but testis had the maximal level when the level per milligram of protein was considered, about 3.0 ng/mg protein, followed by liver, kidney, and heart. About 10-20% of the tissue(75)Se was located in the mitochondria and 50-60% in the post-mitochondrial supernatant fractions in all dietary Se levels. Significant incorporation of(75)Se in the mitochondrial membrane was observed. The percent distribution ratio between the membrane and matrix fractions of the mitochondria remained constant at all dietary Se levels which, in liver was 65∶35, in kidney 55∶45, and in testis 75∶25. However, in heart mitochondria, the distribution of(75)Se between membrane and matrix varied with dietary Se status, the ratio being 82∶18 in the basal group, and 72∶28 and 41∶59 in the 0.2 and 2.0 ppm Se-supplemented groups, respectively. This is indicative of a preferential uptake of(75)Se in the mitochondrial membrane in conditions of deficiency. About 40-60% of the mitochondrial membrane-associated(75)Se was released upon Triton treatment in all the organs. Of the membrane-bound(75)Se, about 10-15% was acid-labile in liver and kidney and 25% in the heart tissue. Possibilities of tissue specific roles, especially in the heart mitochondrial membrane-related processes, are indicated for selenium.
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TL;DR: Electron microscopic observations revealed structural changes such as loss of cristae with proliferative and degenerative changes of the mitochondria in Se deficiency and involvement of Se in maintaining structure and functional efficiency of mitochondria is evident from the present study.
Abstract: Selenium (Se) deficiency in the experimental models, Coturnix coturnix japonica and Corcyra cephalonica, resulted in impaired mitochondrial substrate oxidations and lowered thiol levels. Studies with respiratory inhibitors confirmed reduced mitochondrial electron transport enzyme activities, especially at cytochrome c oxidase (COX), the terminal segment. Enhanced mitochondrial lipid peroxidation in Se deficiency was more pronounced in the heart tissue of the quail compared to other tissues. Glutathione peroxidase (GSH-Px) activity toward H2O2 and cumene hydroperoxide were generally low in the insect muscle tissue and activity toward H2O2 was maximal in the quail heart mitochondria that was not very sensitive to Se status. Lowered COX activity in Se deficiency was more directly correlated with the increased level of lipid peroxidation than with the GSH-Px activity measured, suggestive of Se mediated protective mechanisms independent of GSH-Px. Electron microscopic observations revealed structural changes such as loss of cristae with proliferative and degenerative changes of the mitochondria in Se deficiency. Involvement of Se in maintaining structure and functional efficiency of mitochondria is evident from the present study.
35 citations
TL;DR: The results including the differential response of GR activity to Se or mimosine supplementation are reflective of an effective reductive environment in Se groups and increased turnover of GSH in the presence of Mimosine.
Abstract: Actaptive alterations in glutathione (GSH) metabolism were studied during oxidative stress induced by selenium (Se) deficiency in germinating seedlings ofTrigonella foenum- graecum grown for 72 h and the response to supplementation individually of Se or mimosine was explored. Growth enhancement with improved mitochondrial efficiency was elicited by supplementation of Se at 0.5-0.75 ppm or mimosine at 0.1-0.2 mM. Total thiol and protein levels of mitochondrial and soluble fractions, in general, did not vary significantly with supplementation of either Se or mimosine except that the mitochondrial protein levels in mimosine groups (0.1-0.2 mM) decreased by 20–30%. Mitochondrial glutathione peroxidase (GSH-Px) increased by twofold in activity toward H2O2, cumene hydroperoxide (CHP), and t-butyl hydroperoxide (tBHP) in Se groups, and by 50–60% increase toward H2O2 and CHP but by a twofold enhancement in enzyme activity with tBHP in mimosine groups. Soluble GSH-Px activity increased by 30–40% only in mimosine groups and remained unaltered in Se groups. Glutathione S-transferase activity (GST) in the soluble fraction of both Se and mimosine groups increased dramatically by fivefold to sixfold. Distinct differences were noted in the response of the stressed seedlings toward exposure to Se or mimosine and included a decline in glutathione reductase (GR) activity by 50–60% in both mitochondria and soluble fractions of Se groups and an increase in GR activity of the mitochondria by twofold and of the soluble enzyme activity by 30% in the mimosine groups. Mimosine exposure resulted in a dose-dependent decrease in the γ-glutamyl transpeptidase levels, but, in contrast, a significant enhancement by 50% was noted in the Se group at 0.75 ppm. The results including the differential response of GR activity to Se or mimosine supplementation are reflective of an effective reductive environment in Se groups and increased turnover of GSH in the presence of mimosine.
23 citations
Cites background from "Selenium-mediated biochemical chang..."
...The severe symptoms of oxidative stress prevalent in Se deficiency, well studied in animal systems (13-15), are coincidental with altered glutathione metabolism, including elevation of glutathione S-transferase (GST), a nonselenoenzyme, involved in detoxication mechanisms....
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TL;DR: It is demonstrated for the first time that mimosine, a naturally occuring toxic amino acid, could be a beneficial growth factor in concentrations between 0.1 and 0.2 mM.
Abstract: Oxidative stress during selenium (Se) deficiency in the seedlings ofTrigonella foenum-graecum grown for 72 h was investigated and the response to supplemented levels of Se (0.5-1 ppm) and mimosine (0.05-1 mM) was evaluated. Beneficial effects of Se was maximal at 0.75 ppm. Mimosine, a toxic amino acid, was also found to be beneficial to the growth of the seedlings exposed up to 0.2 mM. When compared to the stressed seedlings, mitochondrial oxygen uptake from seedlings of Se (0.75 ppm) group and mimosine (0.2 mM) group exhibited threefold enhancement in state 3 respiration rate and a controlled state 4 rate, with respiratory control ratios of 5–8. Upon supplementation at the optimal levels, Superoxide dismutase (SOD) activities were enhanced fourfold with Se and eightfold with mimosine in the mitochondria. The soluble activity in mimosine groups increased twofold, but only by 75% in Se groups. Peroxidase activity registered a significant increase by threefold in mitochondria and fourfold in soluble fraction in both Se and mimosine groups. Exposure to Se or mimosine exhibited a differential response in the mitochondrial catalase and ascorbate peroxidase (Asc-Px) activities. In the Se groups, both catalase and Asc-Px in mitochondria decreased by 50–60%, which was contrasted by 60% increase in Asc-Px activity and 40% in catalase activity in mimosine groups. Supplementation with either Se or mimosine evoked similar responses of increases with respect to soluble catalase by twofold to threefold and Asc-Px by 90%. The results of the present study reveal (1) the Prevalence of oxidative stress inT. foenum-graecum during Se deficiency, (2) enhanced mitochondrial functional efficiency mediated by Se and mimosine independently, and (3) an antitoxidative role for mimosine during Se deficiency. The study demonstrates for the first time that mimosine, a naturally occuring toxic amino acid, could be a beneficial growth factor in concentrations between 0.1 and 0.2 mM.
19 citations
Cites background from "Selenium-mediated biochemical chang..."
...Experimental Se deficiency in animals has been widely studied (14-17), which indicates reversible and specific Se-dependent enzyme modulation in a variety of species....
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TL;DR: In this article, the requirement, uptake, and subcellular distribution of Na2 · 75SeO3 in the larvae of C. cephalonica was investigated, and a more fundamental role for selenoprotein in the mitochondrial energy metabolism emerges from these studies.
Abstract: Requirement, uptake, and subcellular distribution of Na2
75SeO3 in the larvae of the insectC. cephalonica was investigated. That Se is well tolerated byC. cephalonica upto an added level of 2 ppm in the diet is suggested by the observed increase in body weight, total protein, and succinate dehydrogenase levels. Significant increases in the State 3 respiration ensued with Se supplementation up to 2 ppm in the mitochondrial oxidation of D-glycerol 1-phosphate, succinate and NADH, along with concomitant unaltered State 4 respiration, leading to enhanced RCR values. Maximal uptake of75Se was registered in the larvae maintained on basal diet when subjected to short-term exposure to 0.5 ppm75Se level. When exposure level was further increased up to 20 ppm, the observed decrease in the uptake of75Se suggested that Se status of larvae itself controlled the tissue uptake. Subcellular distribution pattern revealed maximal incorporation of75Se (cpm/g tissue) in the supernatant fraction, whereas, maximal specific75Se activity (cpm/mg protein) was associated with the mitochondrial fraction. Autoradiography of the soluble fractions indicated the presence of single selenoprotein in the larval group with short term 2 ppm75Se exposure. Inherent Se controls both the extent and the nature of distribution of mitochondrial75Se incorporation. Uptake of45Ca by the insect mitochondria was enhanced by dietary Se up to 2 ppm but was unaffected by addition ofin vitro
75Se in the medium. A more fundamental role for Se in the mitochondrial energy metabolism emerges from these studies.
16 citations
TL;DR: The study reveals a differential response to Se among the β-galactosidase and β-glucosid enzyme of T. foenumgraecum with increase in the levels of β-GalactOSidase activity.
Abstract: Beta-glucosidase and beta-galactosidase activity profile tested in different seeds during 24 h germination revealed reasonably high levels of activity in Vigna radiata, Cicer arietinum, and Trigonella foenum-graecum. In all seeds tested, beta-galactosidase activity was, in general, higher than that of beta-glucosidase. T. foenum-graecum seedlings exhibited maximal total and specific activities for both the enzymes during 72 h germination. Se supplementation as Na2SeO3 up to 0.75 ppm was found to be beneficial to growth and revealed selective enhancement of beta-galactosidase activity by 40% at 0.5 ppm Se. The activities of both the enzymes drastically decreased at 1.0 ppm level of Se supplementation. On the contrary, addition of Na2SeO3 in vitro up to 1 ppm to the enzyme extracts did not influence these activities. Hydrolytic rates of beta-glucosidase in both control and Se-supplemented groups were enhanced by 20% with 0.05 M glycerol in the medium and 30% at 0.1 M glycerol. The rates were marginally higher in Se-supplemented seedlings than the controls, irrespective of added glycerol in the medium. In contrast, hydrolysis by beta-galactosidase showed a trend of decrease in Se-supplemented seedlings compared to the control, when glycerol was present in the medium. Addition of Se in vitro in the assay medium showed no difference in the hydrolytic rate by beta-galactosidase when compared to control, while the activity of beta-glucosidase declined by 50%. Se-grown seedlings showed an enhancement of transglucosidation rate by 40% in the presence of 0.1 M glycerol. The study reveals a differential response to Se among the beta-galactosidase and beta-glucosidase of T. foenum-graecum with increase in the levels of beta-galactosidase activity.
6 citations
References
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TL;DR: Analysis of the line shape of the low field resonance suggests that the broadening observed is consistent with two iron (I = 12) centers with similar effective hyperfine splitting constants.
Abstract: The ferredoxin from parsley has been purified to a high degree. The protein contains 2.0 iron atoms per molecule, has an iron to labile sulfide ratio of unity and consumes 9 moles of mercurial, leading to calculated molecular weights of 10800, 10750 and 10960, respectively. These compare well with the results of amino acid analysis which gave a molecular weight of 10660. The dithionite-reduced material showed an EPR spectrum with the experimental g values: 1.899, 1.959, 2.061. CL− was found to have a specific broadening effect upon this spectrum.
Selenium has been substituted for the labile sulfur of the native protein to yield a biologically active homolog. A new method for this reaction has been developed. The optical and circular dichroism spectra of the oxidized and reduced forms of the selenium protein have been recorded and are compared with the corresponding state of the native protein.
The following isotopic derivatives have been prepared and studied by EPR spectroscopy: 32S56Fe (native), 32S57Fe, 30Se56Fe, 77Se56Fe and 80Se57Fe. The 32S57Fe derivative shows a broadened EPR spectrum but no hyperfine structure is resolved, this is presumably due to the broad line of the native material. The 80Se56Fe spectrum tended toward axial symmetry with apparent g values of 1.937, 1.965, 2.062. This derivative also showed a substantially narrower line width in the z-region. Hyperfine structure is resolved in the z-region of the 77Se56Fe homolog, and the EPR spectrum has been analyzed to determine the number of I = 12 hyperfine centers contributing to the line widths. Hyperfine structure was not resolved in the 80Se57Fe species; analysis of the line shape of the low field resonance suggests that the broadening observed is consistent with two iron (I = 12) centers with similar effective hyperfine splitting constants.
71 citations
TL;DR: A selenium-containing protein of 10,000 molecular weight was purified from the muscle extract of lambs injected with selenia and contains a heme group identical to cytochrome C, and may be a selenum containing cyto chrome.
Abstract: A selenium-containing protein of 10,000 molecular weight, which is absent in muscle of selenium deficient lambs, was purified from the muscle extract of lambs injected with selenium. The absorption, circular dichroic, and magnetic circular dichroic spectra of the protein with and without dithionite markedly resemble the oxidized and reduced spectra reported for cytochrome C. Thus, this protein contains a heme group identical to cytochrome C, and may be a selenium containing cytochrome.
64 citations
TL;DR: This system confirms the essential role of Se in spermatogenesis and provides a model for the evaluation of the primary effect of Se deprivation on the structural development of sperm.
Abstract: Three successive generations of mice were fed a Torula yeast based Se-deficient diet with or without 01 ppm Se in the drinking water The Se-deficient mice, in the course of three generations, showed a decrease in body weight, testis weight, epididymal weight, and sperm production The percentage of morphologically abnormal sperm increased in successive generations The majority of sperm defects were found in the midpiece region of the tail Many of these aberrant sperm were motile A progressive decrease in fertility was noted during the first two generations of Se deficiency This system confirms the essential role of Se in spermatogenesis and provides a model for the evaluation of the primary effect of Se deprivation on the structural development of sperm
58 citations
TL;DR: Normal and selenium-responsive myopathic myopathic lambs were injected with selenum-75 either as sodium selenite or seleno-methionine or both, and rudimentary amounts of this protein were present in the tissues of the myopathic lamb by six weeks of age, suggesting this protein may be implicated in the prevention of white muscle disease in lambs.
Abstract: Normal and selenium-responsive myopathic (white muscle disease) lambs were injected with selenium-75 either as sodium selenite or seleno-methionine. Selected tissues were removed at autopsy 16 hr after injection. The soluble fraction from homogenates of these tissues was subjected to gel chromatography and the effluent monitored for radioactivity and protein content. The elution curves were similar for both sodium selenite and selenomethionine injections. Selenium was bound to two different molecular weight proteins in the kidney and three different molecular weight proteins in the liver, pancreas, and plasma. Four different molecular weight selenium-binding proteins were found in heart and semitendinosus muscle of 2-week-old normal lambs, but only three were found in these tissues of myopathic lambs. This fourth protein, which was absent in myopathic lambs, corresponded to a molecular weight of approximately 10,000. However, by six weeks of age rudimentary amounts of this protein were present in the tissues of the myopathic lamb. This protein may be implicated in the prevention of white muscle disease in lambs.
47 citations