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The effect of selenium (Se) on the reproductive system has been investigated in both humans and vertebrates, but few studies of female fertility and reproduction in invertebrate have been reported. This study is aimed to investigate the effect of SeMet on growth performance and reproductive system after crayfish were fed with graded levels of dietary SeMet (0, 1.49, 3.29, 10.02, 30.27 or 59.8 μg Se/g dry weight) for 60 days. Crayfish treated with the high levels of SeMet (10.02, 30.27 and 59.76 μg Se/g) exhibited decreasing FW and CL in both male and female. Interestingly, Se accumulation was higher in ovary than in other tissues, suggesting that ovary may serve as a target organ for Se accumulation. We found that dietary Se concentration of 10.02 μg Se/g significantly improved the spawning rate, promoted the synchronized spawning, and up-regulated the expressions of mRNA of cdc2 and vitellogenin , with significantly increased E2 and VTG concentrations in hemolymph of female crayfish. However, a marked decrease of the E2 contents and spawning rate was observed in the groups treated with 30.27 and 59.76 μg Se/g diets. In conclusion, the results of this study indicated that the Se had maximum accumulation in ovary, affecting the reproductive capacity by intervening the expression of cdc2 and vitellogenin in the reproductive system. The LOAEL to induce FW was observed in crayfish fed with 10.02 μg Se/g diet, and its value can cause toxicity within the range of natural concentration, so the addition of Se in the feed should be within 10.02 μg Se/g. Image 1 • Se accumulation was higher in ovary than in other tissues. • The LOAEL to induce FW was 10.02 μg Se/g diet. • Se intervened the expression of some key genes in the reproductive system. • High concentration of Se produced reproductive toxicity on female crayfish. The LOAEL to induce FW was observed in crayfish fed with 10.02 μg Se/g diet, and its value can cause toxicity within the range of natural concentration, so the addition of Se in the feed should be within 10.02 μg Se/g. [ABSTRACT FROM AUTHOR]

Abstract A field study in periparturient sows fed different dietary concentrations of either sodium selenite or L-selenomethionine (SeMet) was conducted to evaluate feed intake, haematological and biochemical parameters as well as to describe some key selenium (Se) species, namely selenoprotein P (SelP), selenoalbumin (SeAlb) and selenomethionine (SeMet) as well as total Se in plasma, colostrum and milk. Thirty-two sows were allotted to four treatments from 30 days (d) prepartum throughout on average a 32 d lactation period. Sodium selenite supplemented diets contained 0.40 and 0.60 mg Se/kg feed, while SeMet supplemented feed contained 0.26 and 0.43 mg Se/kg feed. Concentrations of sodium selenite and SeMet in complete feed exceeded the upper limits for total dietary Se and added organic Se, respectively, according to the European Union legislation. Blood samples were collected at initiation of the study, at farrowing and at weaning. Colostrum samples were collected at farrowing and milk samples at weaning. Se species were subjected to liquid chromatography, and total Se and Se species were determined using inductively coupled plasma mass spectrometry. The SeMet supplemented diets resulted in higher feed intake and in higher levels of total Se, SelP, SeAlb and SeMet in colostrum compared with sows fed sodium selenite. Similar results were obtained for levels of total Se and SeMet in milk at weaning. The higher dietary sodium selenite concentration in sows' feed did not increase the Se transfer into colostrum or milk when compared with those receiving the lower level of sodium selenite. However, the increase in serum-Zn from initiation until farrowing, observed in sows fed SeMet as well as the higher glutamate dehydrogenase activity in sodium selenite supplemented sows in this period might indicate a higher requirement of antioxidant defence in sodium selenite-supplemented sows. To our knowledge, the present data on Se species in plasma, colostrum and milk of sows represent the most complete investigation of Se in sows conducted to date. A higher amount of the above-mentioned Se species in the colostrum of sows supplemented with SeMet might strengthen the piglets' antioxidative system and passive immunity as well as improve their average daily weight gain. The higher feed intake in sows fed diets supplemented with SeMet is an interesting finding that warrants further investigation. [ABSTRACT FROM AUTHOR]

Abstract The study was conducted to compare effects of different dietary Se sources (sodium selenite [NaSe], Se-enriched yeast [Se yeast] or L-selenomethionine [SeMet]) and one Se-deficient control diet on the expression of selected genes, hematological and clinical biochemical parameters, and muscle morphology in two parallel trials with finisher pigs. Se concentrations in blood plasma and tissues were also monitored. From the pigs in one of the parallel groups, muscle samples obtained from Musculus longissimus dorsi (LD) before and during the trial were examined. The pigs in the other parallel group were challenged once with lipopolysaccharide (LPS) intravenously. Transcriptional analyses of LD showed that selenogenes SelenoW and H were higher expressed in pigs fed Se-supplemented diets compared with control. Furthermore, the expression of interferon gamma and cyclooxygenase 2 was lower in the Se-supplemented pigs versus control. In whole blood samples prior to LPS, SelenoN, SelenoS and thioredoxin reductase 1 were higher expressed in pigs fed NaSe supplemented feed compared with the other groups, possibly indicating a higher level of oxidative stress. After LPS exposure glutathione peroxidase 1 and SelenoN were more reduced in pigs fed NaSe compared with pigs fed organic Se. Products of most above-mentioned genes are intertwined with the oxidant-antioxidant system. No significant effects of Se-source were found on hematologic parameters or microscopic anatomy. The Se-concentrations in various skeletal muscles and heart muscle were significantly different between the groups, with highest concentrations in pigs fed SeMet, followed by those fed Se yeast, NaSe, and control diet. Consistent with previous reports our results indicate that dietary Se at adequate levels can support the body's antioxidant system. Our results indicate that muscle fibers of pigs fed organic Se are less vulnerable to oxidative stress compared with the other groups. [ABSTRACT FROM AUTHOR]

Abstract: Selenomethionine (SeMet) adsorbs irreversibly from an aqueous solution to the gold surface. The resulting surface layer has a composite character and consists of SeMet and selenohomocysteine (SeHcy), which forms by the hydrolytic cleavage of the first one. The occurrence of these compounds was demonstrated by cyclic voltammetry and EQCM investigations. An anodic scan results in two poorly separated peaks corresponding to the oxidative desorption processes (E 1/2 about 0.70V and E p about 0.92V vs. the Ag|AgCl (3M KCl) electrode, respectively). The first one corresponds to the oxidation of SeHcy to RSeO2H (where R stands for HO2CCH(NH2)(CH2)2−) whereas the second results from the anodic conversion of SeMet to RSeO3H with RSeO2H as a possible intermediate. SeMet oxidation may continue in the region of gold oxide formation if not completed in the pre-oxide region. Partial decomposition of RSeO2H gives rise to H2SeO3 which was evidenced by its reduction reaction to Se(0) at about 0.25V. In turn, Se(0) can be oxidized back to H2SeO3 at about 0.83V. Surface Se(0) inhibits the electron transfer reaction of the redox couple. Ionization of the amino acid functions in the adsorbed state was investigated by capacitance vs. pH determinations. It was thus found that the carboxyl ionization constant (pK a1) shifts from 2.19 in the aqueous solution to 5.1 in the adsorbed state whereas the adsorption has almost no effect on the ionization constant of the amino group (pK a2 =9.05 in the adsorbed state vs. 9.15 in the solution form). Adsorption effect on the ionization constants was accounted for by the interplay of the effect of the surface charge on the local activity of the hydrogen ion, on one had, and intramolecular hydrogen bonding, on the other hand. A SeMet modified electrode can bind reversibly the copper(II) ion in the same way as cysteine and homocysteine proving that the amino acid functions are not involved in surface interactions. Selenium head group forms therefore the link between the adsorbate and the gold surface. [Copyright &y& Elsevier]

Several mechanisms regarding the developmental and reproductive toxicity of l -selenomethionine (SeMet) in freshwater fish have been widely reported. However, limited information was available on endocrine-disrupting effects of SeMet. In this study, zebrafish larvae (day 24 post-fertilization) were exposed to environmentally-relevant levels of dietary SeMet (control, 1.11 ± 0.11, 3.59 ± 0.20, 10.80 ± 0.52, 29.19 ± 0.46, and 58.63 ± 0.70 μg Se/g d.w. diet) for 90 days until sexual maturity. For the first time, a gender difference in the effect of SeMet on body mass of zebrafish was observed. The lowest observed adverse effect level (LOAEL) in male was 10.80 ± 0.52 μg Se/g d.w., while it was 29.19 ± 0.46 μg Se/g d.w. in female. Chronic exposure to dietary SeMet reduced the percentage of early vitellogenic oocyte in female and the percentage of spermatid in male by inhibiting the growth hormone/insulin-like growth factors (GH/IGFs) and hypothalamus-pituitary-gonad (HPG) systems, which was characterized by significant decreases in the transcriptional levels of gh , igf1 , era , and ar. Se content in the liver of male was significantly higher than that in female when dietary Se level reached 10.80 ± 0.52 μg Se/g d.w.. Furthermore, the zinc content in the livers and gonads of both female and male treated with 29.19 ± 0.46 and 58.63 ± 0.70 μg Se/g d.w. diets was significantly reduced. Reduction of zinc ion not only led to the significantly upregulated transcriptional levels of zip1 and znt2 , but also downregulated transcriptional levels of znf219l and sp7. In summary, this study provides a new evidence that chronic exposure to high level of dietary SeMet (≥10.80 μg Se/g d.w.) could impair the development and reproduction of zebrafish with gender difference by interfering the GH/IGFs and HPG systems. Moreover, disruption of zinc ion homeostasis might exacerbate the toxicity of Se to zebrafish. Image 1 • The LOAEL in male was 10.80 μg Se/g, while it was 29.19 μg Se/g in female. • SeMet impaired growth and reproduction by interfering GH/IGFs and HPG systems. • Chronic exposure to high level of dietary SeMet disrupted zinc ion homeostasis. [ABSTRACT FROM AUTHOR]

Studies in mammals proved dietary organic selenium (Se) being superior to inorganic Se regarding effects on growth performance, antioxidative status, immune response, and Se homeostasis. However, the picture of possible effects of different Se sources and – levels can be expanded. The present field study evaluated the effects on weight gain, hematological and selected biochemical variables as well as plasma concentrations of vitamin E (vitE), total Se and selenobiomolecules in piglets throughout the suckling period. Piglets were monitored from birth to 38 days of age (d). The mother sows' diets were enriched with l -selenomethionine (SeMet-0.26 and -0.43 mg Se/kg feed) or sodium selenite (NaSe-0.40 and -0.60 mg Se/kg feed) from 1 month prior to farrowing until the end of lactation period. Piglets received pelleted feed supplemented with Se similarly to the sows' diets from one week of age. Selenite at 0.40 mg Se/kg (NaSe-0.40) represents a common Se source and -level in pig feed and served as control diet. From 24d, piglets in SeMet-groups had higher mean body weight (BW) compared with piglets from sows fed NaSe-0.40. Furthermore, from five-d and above, piglets from sows fed NaSe-0.60 had significantly higher BW than offspring from sows fed NaSe-0.40. Neonatal piglets in group SeMet-0.43 had significantly lower red blood cell counts (RBC), hemoglobin (Hgb) and hematocrit (Hct) concentrations compared with piglets from sows fed with NaSe-0.40. Neonatal and 5d-old piglets in group SeMet-0.26 showed higher gamma-glutamyl transferase activity than piglets in group NaSe-0.40. From five d and above, group NaSe-0.60 excelled with increased specific hematological variables culminating at age 38d with increased Hct, mean corpuscular volume (MCV), and MC hemoglobin (MCH) as well as increased activities of aspartate transaminase and lactate dehydrogenase compared with the other groups. Generally, offspring in the SeMet groups had higher total Se-concentrations in plasma than those from sows fed selenite, and showed a dose-response effect on plasma Se-concentrations. Furthermore, SeMet-fed piglets had higher plasma levels of the selenoproteins (Sel) glutathione peroxidase 3 (GPx3) and SelP as well as selenoalbumin. Plasma vitE levels were significantly negatively correlated with RBC throughout trial period. Maternal supplementation with SeMet during gestation influenced hematology and clinical biochemistry in neonatal piglets in a different way than in offspring from sows receiving selenite enriched diets. Growth performance was positively influenced by both dietary Se source and Se level. Higher plasma levels of GPx3 observed in piglets receiving SeMet probably improved the protection against birth or growth related oxidative stress. These might prime the piglets for demanding situations as indicated by higher weight gain in offspring from sows fed with SeMet-supplemented diets. Our results on some enzyme activities might indicate that piglets fed NaSe-0.60 had to cope with increased levels of oxidative stress compared with those originating from sows fed SeMet or lower dietary levels of selenite. We assume that combining inorganic and organic Se sources in complete feed for breeding sows might be beneficial fro reproduction and the offspring's performance. [ABSTRACT FROM AUTHOR]