Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Essentially all of the selenium in the rat spermatozoon is bound to a polypeptide of Mr 15,000-17,000 confined to the capsule that surrounds the sperm mitochondria. Isoelectric focussing of isolated 75Se-labelled, carboxymethylated mitochondrial capsule protein (MCP) reveals the presence of at least four radioactive components, with a predominant charge isomer at pI4.6. The sperm selenoprotein appears to be identical with MCP, as judged by the exact coincidence of radioactivity and protein stain during two-dimensional electrophoresis. The temporal pattern of 75Se-labelling of rat caput epididymal spermatozoa after intratesticular 75Se injection suggests that maximum incorporation of 75Se into MCP occurs in step 7-step 12 spermatids and that 75Se uptake ceases during step 15 of spermiogenesis. The developmental appearance of sperm selenoprotein in rat testis therefore appears to lag several days behind that reported for MCP in mouse testis, suggesting the presence of selenium-free MCP in immature germ cells. SDS gel electrophoretic analysis of testis subcellular fractions 24 h after 75Se injection into rat testis at 21, 28 and 90 days of age indicates that sperm selenoprotein first appears in very low concentration during late meiosis and that its concentration increases sharply during early spermiogenesis. Additional 75Se-labelled polypeptides were detected on the gels, most of them of higher molecular weight than MCP. At least two of these (Mr 47,000 and 54,000) displayed a marked decrease in labelling between 5 and 24 h after injection into adult testis, coincident with a comparable increase in 75Se-labelled MCP, indicating that they may be precursors of MCP.
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PMID:A developmental study of rat sperm and testis selenoproteins. 344 22

The concentrations of selenium in the reproductive organs, seminal fluid and serum of human males and bulls were analysed using an atomic absorption spectrometer with Zeeman background correction. The mean (+/- SD) concentration of selenium in human seminal fluid (33.4 +/- 14.1 micrograms/l, n = 70) was less than half the level detected in serum (78.2 +/- 9.9 micrograms/l, n = 32). In bulls, the mean selenium concentration in seminal fluid (457.4 +/- 108.7 micrograms/l, n = 113) was about nine times higher than in human males, while the level in serum (49.1 +/- 5.1 micrograms/l, n = 94) was significantly (P less than 0.001) lower than in human serum. The selenium concentration (500 +/- 244 micrograms/l) in the bovine seminal vesicle secretions were comparable to those in the seminal fluid and this gland appears to be mainly responsible for the high selenium levels in the seminal fluid. The mean selenium concentration in reproductive tissues of both species was highest in the testes. The distribution of selenium in the bovine epididymis was biphasic. The testicular and epididymal selenium are associated mainly with macromolecules of the spermatogenic cells and spermatozoa. It was concluded that studies in farm and laboratory animals do not necessarily form a reliable basis for conclusions with regard to human male reproduction, since selenium may have a different role and importance in the reproduction of various species.
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PMID:Selenium in reproductive organs, seminal fluid and serum of men and bulls. 355 56

When rats are fed a selenium-deficient diet, the glutathione peroxidase activity of epididymal fat-cells decreases to 5-9% of that of control rats fed the same diet supplemented with 0.5 p.p.m. of selenium as sodium selenite. [1-14C]Glucose oxidation in fat-cells from rats fed a selenium-deficient diet is unresponsive to the action of t-butyl hydroperoxide, which stimulates 14CO2 formation from [1-14C]glucose 4-fold in control rats. Insulin enhances [1-14C]glucose oxidation and incorporation into lipids in fat-cells from both groups of rats; however, the response elicited is reduced in fat-cells prepared from selenium-deficient animals. The 'C-1/C-6 ratio' (ratio of glucose C-1 to glucose C-6 oxidized) is enhanced by insulin to a similar degree in fat-cells from both groups of animals. The stimulatory action of Zn2+ and dithiothreitol on [1-14C]glucose oxidation observed in fat-cells from selenium-supplemented rats is greatly reduced in fat-cells from selenium-deficient rats. [1-14C]Glucose oxidation in fat-cells from both groups of animals is highly sensitive to the stimulatory action of adenosine. It is concluded that the enhanced formation and glutathione-linked destruction of H2O2 plays, at the most, only a minor role in the stimulation of the flux of glucose through the pentose phosphate pathway elicited by insulin, although elimination of glutathione peroxidase activity may influence the action of insulin on glucose oxidation. Production and subsequent destruction of H2O2 may play an important role in the stimulatory action of Zn2+ and dithiothreitol on fat-cell [1-14C]glucose oxidation.
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PMID:The effect of selenium-deficiency on rat fat-cell glucose oxidation. 635 53

The effect of dietary selenium on the subcellular distribution of selenium-dependent glutathione peroxidase (SeGSH-Px) activity in rat liver, epididymal fat pad, and seminal vesicle was determined. Tissues were fractionated by differential centrifugation, and the subcellular distribution of SeGSH-Px activity was determined by comparison with the distribution of biochemical marker enzymes. Liver SeGSH-Px activity was located in both the cytosol and mitochondria. In epididymal fat pad and seminal vesicle, SeGSH-Px activity was located primarily in the cytosol; association with another subcellular organelle, however, was indicated. In liver and epididymal fat pad, SeGSH-Px activity increased linearly, and, in the seminal vesicle, increased linearly and quadratically, with increasing dietary selenium concentration. Distribution of SeGSH-Px activity among the cellular fractions from the tissues, however, was not affected by dietary selenium supplementation.
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PMID:Effect of selenium on the subcellular distribution of glutathione peroxidase in rat liver, epididymal fat pad and seminal vesicle. 682 10

The outer membranes of mitochondria of mammalian sperm are encased in a keratinous structure known as the mitochondrial capsule. The experiments in the present study were designed to resolve a controversy surrounding the intracellular localization, developmental expression, and selenium-content of a cysteine-rich 17-20 kD protein that has been reported to constitute the major structural protein in the mitochondrial capsule of mammals. An antibody to a synthetic oligopeptide based on the predicted sequence of mouse cysteinerich protein recognizes a 24 kD protein in epididymal sperm tails of mice. The 24 kD protein does not appear to be a selenoprotein because: (1) it is not labeled with 75Se-selenite in seminiferous tubule culture; (2) cleavage with cyanogen bromide and translation of T7 RNA polymerase transcripts in vitro indicate that the translation start site is located downstream of potential UGA selenocysteine codons in the mouse cysteine-rich mRNA; (3) the reading frame encoding the cysteine-rich protein in rat lacks inphase UGA selenocysteine codons. Light and electron microscopy immunocytochemistry detects the cysteine-rich protein first during step 11 of spermiogenesis in the mouse demonstrating that the cysteine-rich protein mRNA is under temporal translational control. Electron microscope immunocytochemistry reveals that the cysteine-rich protein is evenly distributed in the cytoplasm in spermatids in steps 11 through early step 16 in mouse, and that it is associated with the outer mitochondrial membranes of spermatids in late step 16 and epididymal spermatozoa.
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PMID:Developmental expression, intracellular localization, and selenium content of the cysteine-rich protein associated with the mitochondrial capsules of mouse sperm. 891 43

The epididymis-specific glutathione peroxidase was purified from the porcine cauda epididymal fluid in order to analyze its enzymatic activity and roles in the epididymis. The purified protein was found to consist of four identical 23 kDa subunits. The complementary DNA encoding the 23 kDa subunit was cloned from the cDNA library of the porcine proximal caput epididymis, only where the 23 kDa subunit is expressed. Although the selenocysteine codon (TGA) is contained in the cDNA of the other cytosolic type of glutathione peroxidases, it is replaced by cysteine codon (TGT) in the 23 kDa subunit cDNA, similarly to the results previously obtained for cDNAs encoding the epididymis-specific form of the secreted glutathione peroxidases of mouse, rat and monkey. By the direct analysis of the selenium, the purified protein was proved to contain no selenium atom in the molecule. The activities of the purified epididymis-specific glutathione peroxidase toward hydrogen peroxide or organic hydroperoxides were by far lower than the activity of cytosolic selenium-dependent glutathione peroxidase (less than 0.1%). In addition, the concentration of glutathione in the porcine epididymal fluids was about 20 microM, which is much lower than the optimal concentration for the glutathione peroxidase activity of the purified protein. These results strongly suggest that this protein is enzymatically quiescent at least in the porcine epididymal fluid. An immunocytochemical study showed that this protein was found to bind to the acrosomal region of the epididymal sperm and to disappear during the acrosome reaction. Furthermore, this protein significantly retarded the acrosome reaction induced in vitro. The possibilities have been discussed that it protects sperm from the premature acrosome reaction and maintains sperm fertilizing ability in the epididymis.
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PMID:Molecular cloning and characterization of the epididymis-specific glutathione peroxidase-like protein secreted in the porcine epididymal fluid. 927 Dec 55

Effect of repeated oral administration of hexachlorocyclohexane (HCH; 10 and 20 mg/kg body weight per day for 7, 15 and 30 days) on antioxidant defence system and lipid peroxidation (LPX) in the testis was compared between immature (15-day-old) and mature (90-day-old) rats. In both age-groups of rats, the pesticide elicited a significant decrease in the activities of cytosolic superoxide dismutase (SOD; total and CN(-)-resistant) and catalase, and ascorbic acid content together with an increase in the levels of LPX (both in crude homogenate and subcellular fractions) and H2O2. Testicular glutathione peroxidase (GPx; total and non-selenium-dependent) activity was enhanced in both the age-groups of rats while the testicular glutathione content as well as glutathione reductase activity remained unaltered. HCH treatment resulted in a decrease of total epididymal sperm number with a higher incidence of dead and damaged spermatozoa, and sperms having anomalous head. Statistical analyses suggest that the alterations in the testicular antioxidant defence profile in the rat are not only dependent on the duration of pesticide treatment, but also influenced by age.
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PMID:Age-related changes in rat testicular oxidative stress parameters by hexachlorocyclohexane. 1035 Jan 90

Selenium is an essential micronutrient for animals. To determine whether its excess in diet induces morphological changes within the male reproductive system, a detailed qualitative and quantitative evaluation of the changes in the histology of the testis and cauda epididymis was undertaken in male rats. Adult male albino rats were fed 6 and 8 ppm Se in diet for 6 and 9 weeks. Each male consuming 6 ppm Se was mated with two untreated females, their offsprings were allowed to mature upto 12 weeks of age. The testes and cauda epididymes of male rats were prepared for light microscopy. Excess of dietary Se caused dose-time-dependent reduction in body weight and reproductive organ weights but increase in number of morphologically abnormal spermatozoa. Histopathological studies of the testes and cauda epididymis have revealed that Se-rich diets cause dose-time-dependent reduction in tubular diameter, epithelial height, number of spermatogenic cells and disintegration of cellular associations in the seminiferous tubules of testes along with reduction in the diameter of cauda epididymal tubules and pseudostratification of their epithelial lining. Progeny (feeding on normal diet) of paternally treated rats has shown retarded growth.
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PMID:Effects of dietary selenium (SE) on morphology of testis and cauda epididymis in rats. 1094 13

Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is a selenium (Se)-dependent glutathione peroxidase. It is reported that the relative PHGPx mRNA levels are much higher in the testis than in the other tissues. We have analyzed the existence and structure of the PHGPx mRNA in rat sperm and the changes in the level of the PHGPx mRNA after feeding with Se-deficient diets. We used 8-wk-old male Wistar strain rats given Se-adequate feed (control group, n = 5) and Se-deficient diets with marginal levels of Se (0.03 ppm or less) (Se-deficient group, n = 5) for 4 wk. The existence and level of the PHGPx mRNA in the cauda epididymal sperm, testis, and liver from the Se-adequate rats were analyzed by the reverse transcription-polymerase chain reaction and the Southern blotting method. As a result, the existence of the PHGPx mRNA was demonstrated in the cauda epididymal sperm as well as in the testis and liver. Moreover, the subtype of the PHGPx mRNA in the rat sperm was the mitochondrial-type mRNA, which included a region corresponding to the mitochondrial transfer leader sequence. These results imply that the intracellular localization of PHGPx may be regulated by the transcription level. On the other hand, there was no significant difference between the control group and the Se-deficient group in the Se level of the cauda epididymal sperm and the level of the PHGPx mRNA. In conclusion, it has been demonstrated that the PHGPx mRNA exists in rat sperm for the first time. The analysis of the PHGPx mRNA in the sperm would be a useful tool for investigating the disfunction caused by the disorder of the level or structure of the PHGPx in the sperm.
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PMID:Analysis of the phospholipid hydroperoxide glutathione peroxidase mRNA in the rat spermatozoon and effect of selenium deficiency on the mRNA. 1104 1

Selenium (Se) and selenoproteins such as glutathione peroxidases are necessary for the proper development and fertilizing capacity of sperm cells. Phospholipid hydroperoxide glutathione peroxidase (PHGPx, E.C. 1.11.1.12) is a monomeric seleno-enzyme present in different mammalian tissues in soluble and bound form. Its function, like the other glutathione peroxidases, was originally viewed as a protective role against hydroperoxides, but direct and indirect evidence indicates that it has additional regulatory roles. PHGPx is present in testis cells and sperm cells, and its appearance is hormone regulated. We present here biochemical data, which clearly indicate that the enzyme specific activity in rat is age-dependent during the life-span monitored (from 36 to 365 days), with a maximum at 3 months of age in the testis germ cells and at 6 months of age in the isolated epididymal sperm cells. Western blotting and immunocytochemical analysis by means of anti-PHGPx antibodies show the different distribution and the strong binding of PHGPx in the testes and sperm cell subcellular compartments (nucleus, acrosome, mitochondria and residual bodies) of rats of different age. The presence of the protein exhibits in the testis cells a pattern different from that of the catalytic activity, with a maximum at 6 months of age. The subcellular distribution of PHGPx is qualitatively, but not quantitatively, unchanged during ageing. These different behaviours are compared and discussed.
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PMID:Enzymatic and immunochemical evaluation of phospholipid hydroperoxide glutathione peroxidase (PHGPx) in testes and epididymal spermatozoa of rats of different ages. 1190 56


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