High Selenium Concentrations Research Articles

해남 모이산 인근 토양 및 농작물의 셀레늄(Se) 분포 특성

해남 모이산 천열수 광산 주변의 열수변질작용에 의한 암석, 토양과 농작물간의 셀레늄의 상호작용을 규명하기 위하여, 모이산 인근의 토양과 농작물 시료를 채취 분석하였다. 토양시료는 6개의 산 토양과 6개의 밭 토양을 대상으로 수분함량, pH, ICP, XRD, XRF 분석을 통해 구성 광물과 원소함량을 분석하였으며, 농작물 시료는 토양과의 관계를 파악하기 위해 이 지역에서 재배된 양파와 대파를 대상으로 원소함량을 분석하였다. 토양에 대한 XRD 분석 결과, 주요 구성광물은 석영과 장석이며, 그 외 열수변질작용에 의해 일라이트, 녹니석과 적철석을 포함하고 있는 것으로 나타났다. 산 토양과 밭 토양의 pH는 각각 4.6~4.9와 5.2~6.7로 나타났는데, 산 토양에 비하여 밭 토양의 pH가 높게 나타난 것은 영농에 의한 비료시비가 원인으로 판단되었다. 원소함량 분석 결과, 비료의 영향이 크게 작용하는 밭 토양에서 산 토양에서는 검출되지 않았던 K(24.81~79.49 ppm), Ca(29.27~116.33 ppm) 등이 다량 함유한 것으로 나타났다. 이러한 경향은 작물에서도 나타나는데, 상대적으로 높은 농도의 K(116.89~169.79 ppm), Ca(20.18~32.29 ppm)가 농작물에 흡수되어 있는 것으로 분석되었다. 토양 시료에서의 Se 함량은 18.35~70.31 ppb의 범위로 분석되어 분석 시료간 유의미한 차이를 나타내지는 않았으나, 양파(119.48~179.50 ppb)와 대파(146.65 ppb)에서는 많은 양의 Se이 검출되었다. 이는 작물에 따라 각 원소에 대한 흡수율이 상이하여 농축도 역시 다르게 나타나는 것으로 판단되었다. Samples from soils and crops were collected and analyzed in order to investigate the interactions of selenium among rocks, soils, and crops by hydrothermal alteration near epithermal mines in the region of Mio-san, Haenam. Soil samples included 6 samples each from mountain and farm area and compositional minerals and their contents were analyzed by water content, pH, ICP, XRD, XRF. Crop samples from onion and scallion were analyzed for chemical composition to elucidate the relationship with soils. Results from XRD analysis for soil samples showed that major compositional minerals are qualtz and feldspar, and illite, chlorite, hematite formed by hydrothermal alteration were included on a small scale. The pH ranges of soil samples from mountain and farm were measured at 4.6~4.9 and 5.2~6.7, respectively. The higher pH in farm soils may result from fertilization during agricultural activities. Results from ICP analysis showed that, compared to soil samples from mountain area with no potassium and calcium, significant amount of K and Ca were detected in soil samples from farms which is affected by fertilization. In a similar manner, potassium and calcium were absorbed and detected in crop samples at relatively high concentrations (116.89~169.79 ppm for K and 20.18~32.29 ppm for Ca). While the selenium contents in soil samples ranged from 18.35 ppb to 70.31 ppb which showed no significant difference, high concentrations of selenium were detected in onion (119.48~179.50 ppb) and scallion (146.65 ppb). These difference in enrichment for each element may result from the distinctive adsorption characteristics depending on crops.

Investigation of biochemical function of selenium and its influence on the content of protein fractions and peroxidase activity in maize seedlings

The release of elemental selenium on the root surface of maize (Zea mays L., variety Krasnodarskii 29/AMV) seedlings observed in response to the addition of selenium-organic preparation DAFS-25 (diacetophenonyl selenide) to the nutrient Knop solution and accompanied by inhibition of growth of the roots was investigated. This process was completely suppressed after the addition of cysteine to the above solution containing 10–2 g/L DAFS-25, with the inhibiting effect was attenuated as well. In addition, DAFS-25 exerted impact on nitrogen exchange in the plants as judged by elevating the protein fraction of albumins in the roots almost by a factor of two due to at the expense of decreasing the content of glutelin, prolamine, and globulin fractions by 43, 25, and 26%, respectively. In the case of the action of DAFS-25 in combination with cysteine the quantitative composition of the above proteins very closely resembled that of the control plants indicating that cysteine behaves as antidote. It was found that DAFS-25 exerted a similar action on the content of albumins in the above-ground part of maize seedlings where this value drastically increased (by a factor of 4.5) on the background of total protein content elevation. In addition, this preparation at the highest concentration tested stimulated the activity of peroxidase in both the roots (by 63%) and the above-ground part of seedlings (by 112%). However, this effect of DAFS-25 was strongly inhibited after addition of cysteine to the nutrient solution. Evaluation of selenium content in the same parts of the control seedlings showed that they contain only a little amount of this element. The highest content of selenium in the above plant tissues was found after addition of DAFS-25 to the nutrient solution that provides evidence for its decomposition directly on the surface of the roots. Such an action of DAFS-25, like its impact on the peroxidase activity, was markedly attenuated in the presence of cysteine.

Preparation of elemental selenium-enriched fermented milk by newly isolated Lactobacillus brevis from kefir grains

A Lactobacillus brevis strain CGMCC No. 6683 that can survive at high selenium concentrations was isolated from kefir grains. Using a scanning electron microscope equipped with an energy dispersive X-ray spectroscope, it was shown that L. brevis CGMCC No. 6683 reduced sodium selenite into elemental selenium. L. brevis CGMCC No. 6683 was then pre-treated with sodium selenite to prepare selenium-enriched L. brevis. To study the selenium-enriched yoghurt, selenium-enriched L. brevis was co-fermented in skimmed milk with traditional yoghurt starter culture (Streptococcus thermophilus and Lactobacillus bulgaricus). Results showed that it enhanced selenium concentration in the selenium-enriched yoghurt, and more importantly, elemental selenium was detected in the selenium-enriched yoghurt. The isolated L. brevis provides a new way of preparing a functional dairy product: elemental selenium-enriched fermented milk.

Intoxicação por selênio em suínos no Sul do Brasil

São descritos dois surtos de intoxicação por selênio em suínos na região Sul do Brasil. Foram acometidos leitões em fase de creche, entre 27 e 22 dias, com mortalidade variando de 16% a 15,3% (Surto 1 e 2 respectivamente). Os suínos apresentaram poliomielomalacia simétrica focal e lesões de casco, que inicialmente eram caracterizadas por uma linha avermelhada na borda coronária que evoluía nos suínos sobreviventes para desprendimento do casco. Os sinais clínicos iniciaram após seis dias (Surto 1) e 30 horas (Surto 2) da introdução da ração com alto teor de selênio. O surgimento dos sinais foi abrupto, caracterizado por andar cambaleante, com evolução para paralisia dos membros pélvicos e posteriormente tetraparesia. Macroscopicamente observaram-se focos circulares amarelados com áreas deprimidas mais escuras, restritas ao corno ventral da substância cinzenta em intumescências cervical e lombar. Microscopicamente essas áreas corresponderam à malacia da substância cinzenta, caracterizada por microcavitações, perda neuronal, cromatólise, neuronofagia, infiltrado de células Gitter, microgliose, astrócitos de Alzheimer tipo II e proliferação de células endoteliais evidenciadas na imunohistoquímica (IHQ) para fator de von Willebrand. Ainda, no segundo surto, dois animais apresentaram vacuolização difusa do citoplasma de neurônios e em um suíno foram observados astrócitos gemistocíticos. Na IHQ para GFAP ficou evidenciada uma astrocitose e astrogliose. Além dessas alterações medulares, em dois suínos observou-se, polioencefalomalácia simétrica no tronco encefálico. Em amostras de ração, detectou-se 3,38ppm (Surto 1) e 154ppm (Surto 2) de Se/kg e em amostras de fígado foram encontradas dosagens superiores a 3,34ppm (variando de 3,34 até 10ppm). No Surto 2, após 44 dias da retirada da ração, foi realizada eutanásia de seis suínos para monitoramento de níveis hepáticos de selênio (dois suínos controles e quatro sobreviventes ao surto) e todos apresentaram níveis normais de selênio no fígado.

Electro-biochemical reactor (EBR) technology for selenium removal from British Columbia’s coal-mining waste waters

The weathering of coal mine waste rock releases iron, calcium, sulfate and associated trace elements like selenium (Se). Nitrogen species are also found in association with coal-mining drainages mainly due to the leaching of residual blasting compounds. Elevated concentrations of Se are a ubiquitous occurrence in coal-mining environments in British Columbia. A major concern with waterborne Se in British Columbia is the potential for its bioaccumulation in aquatic food chains. Treatment to remove Se from coal-mining waste waters has proven to be challenging for conventional water-treatment technologies. Compounding this challenge, many streams are characterized by high flows and low selenium concentrations. Conventional membrane and ion exchange treatments produce concentrated brine streams that are difficult to treat or require disposal. Conventional biotreatment systems use excess nutrients to provide the required electrons to compensate for inefficient and variable electron availability, as well as to adjust reactor chemistry. This paper’s electro-biochemical reactor (EBR) technology provides a controllable and consistent supply of useable electrons to the microbes directly at a low voltage potential (1–3 V) and low current. In this manner, the EBR technology overcomes the shortcomings found in conventional systems, as it reduces the required nutrient addition and provides a more controllable, efficient, economical and robust biotreatment system. Additionally, the EBR process does not produce excess solids or biomass; therefore, solids management post-treatment is not required. Laboratory EBR bench-scale and on-site pilot-scale systems were used to treat five British Columbia coal-mine waste waters; influent Se concentrations ranged from 35 µg/L to 531 µg/L. Se treatment targets for the tested waters ranged from 5 to 10 µg/L. Mean Se concentrations in EBR effluents ranged from 0.5 µg/L to 1.4 µg/L, while reducing sulfate concentrations. The test data demonstrate that the EBR technology is an effective Se removal option for British Columbia’s coal-mining waste waters.

Effects of commercial selenium products on glutathione peroxidase activity and semen quality in stud boars

The aim of this study was to determine how dietary supplementation of inorganic and organic selenium affects the selenium concentration and glutathione peroxidase activity in blood and sperm of sexually mature stud boars. Twenty-four boars of the Large White, Landrace, Pietrain and Duroc breeds of optimal breeding age (on average 2.5 years old) were used. The study lasted 90 days. The boars were randomly assigned to one of three dietary treatment groups: T1=control; no added selenium (n=8 boars), T2=added 0.3ppm inorganic selenium (sodium selenite, Microgran® Se 1% BMP) (n=8 boars), and T3=added 0.3ppm organic selenium (Se-yeast, Sel-Plex 2000®) (n=8 boars). The concentration of selenium was determined in whole blood and semen, while the activity of glutathione peroxidase (GPx) was measured in blood plasma and semen. In order to measure GPx activity in semen, reactivation of the enzymatic GPx activity was performed. The determined selenium concentration in blood was lowest in the non-supplemented group of boars. Blood plasma GPx activity was higher in boars fed organic selenium than in boars fed a diet without supplemented selenium. While the supplementation of sodium selenite significantly increased GPx activity in boar semen. The highest-concentration of selenium in semen at the end of the trial was determined in the group of boars supplemented with organic selenium, somewhat lower in boars fed supplemented inorganic selenium, and the lowest in the non-supplemented group of boars. The only significant difference between the selenite and Se-yeast diet supplementation was observed in the Se concentration of the semen. The supplementation of selenium affected semen quality, and organic selenium improved the progressive motility of the spermatozoa and increased their resistance in hypo-osmotic and thermal tests. The storage ability of short term preserved semen was improved by organic selenium supplementation, as well as also increasing the fertility rate in gilts.

Selenium levels in patients with autoimmune thyroiditis and controls in lower Austria.

Autoimmune thyroiditis (AIT) is one of the most common autoimmune diseases; genetic as well as environmental factors contribute to its pathogenesis. The thyroid is the organ with the highest selenium content per unit weight. Selenium status appears to have an impact on the development of thyroid pathologies. We investigated a possible difference of selenium serum levels as a marker of nutritional selenium supply between patients with AIT in central Lower Austria and a matched group of healthy persons living in the same region. Selenium serum levels in the patients with AIT were 98.0 ± 15.6 μg/l. A significant difference to the matched group of normal persons, whose selenium serum levels were 103.2 ± 12.4 μg/l, could not be detected by the t-test (p>0.05). We considered the serum selenium levels to be indicators of selenium supply (by alimentation). A serum level of 120-160 μg/l of selenium represents the normal range. According to this, most patients and control persons showed mild to moderate selenium deficiency (80-120 μg/l selenium). Although our data present slightly higher selenium levels in normal persons than in patients with AIT, this weak and statistically insignificant trend is not sufficient to support the conclusion of a link between inadequate selenium supply and autoimmune thyroid disease.

Comparison of Trace Element, Metal, and Metalloid Contents in North and South Korean Plants

When relations improve between North and South Korea, there will be demand for North Korean edible plants because of the low labor cost and similar environmental conditions. However, there is no reliable information about trace elements, metals, and metalloids in edible plants from North Korea. Selenium (Se) and germanium (Ge) have positive effects on basic human health and are therapeutical in diverse illnesses. Metal and metalloid (Cd, Pb) poisoning, on the other hand, can cause many health problems. Plants collected from North Korea had higher selenium content than those from South Korea. Although none of the collected species exceeded the permissible levels of cadmium and lead, their content in plants was significantly higher in North Korea than in South Korea. The high metal contents in plants collected from North Korea may be associated with the soil physicochemical properties as well as the accumulated amounts of elements in the soil.

Effects of dietary selenium, sulphur and copper levels on selenium concentration in the serum and liver of lamb.

Thirty-two lambs were distributed in eight treatments under 2×2×2 factorial experiment to compare the effects of two levels of selenium (0.2 to 5 mg/kg dry matter [DM]), sulphur (0.25% and 0.37%) and copper (8 and 25 mg/kg DM) levels on selenium concentration in liver and serum of lambs. A liver biopsy was done on all animals and blood samples were collected from the jugular vein prior to the beginning of the treatments. The blood was sampled every thirty days and the liver was sampled after 90 days, at the slaughter. Increasing differences were noticed during the data collection period for the serum selenium concentration, and it was found to be 0.667 mg/L in animals fed with 5 mg Se/kg DM and normal sulphur and copper concentrations in their diet. However, a three-way interaction and a reduction of selenium concentration to 0.483 mg/L was verified when increasing copper and sulphur concentration levels to 25 ppm and 0.37% respectively. The liver selenium concentration was also high for diets containing higher selenium concentrations, but the antagonist effect with the increased copper and sulphur levels remained, due to interactions between these minerals. Therefore, for regions where selenium is scarce, increasing its concentration in animal diets can be an interesting option. For regions with higher levels of selenium, the antagonistic effect of interaction between these three minerals should be used by increasing copper and sulphur dietary concentrations, thus preventing possible selenium poisoning.

Clavaria Mushrooms and Extracts: Investigation on Valuable Components and Antioxidant Properties

Two Clavaria mushrooms were investigated as sources of antioxidant compounds, essential trace elements Selenium and Zinc, and as efficient antioxidants in elimination/inhibition of different radical species. Using HPLC method, pistillarin-rare siderphore compound characterized with high antioxidant activity, was detected in both extracts. A higher content of pistillarin has been measured in C. pistillaris extract. The same extract contained the higher content of Selenium, 3.051μg/g. Both extracts showed important antioxidant activity. For C. pistillaris extract lower IC50 value has been measured and higher antioxidant activity against O2− radical has been detected. Although the content of pistillarin was higher in the case of C. pistillaris, at the concentration of 0.2 mg/ml C. fennica extract showed just some higher antioxidant activity against ·OH radicals, 82 and 87%, respectively.

The chronic autoimmune thyroiditis quality of life selenium trial (CATALYST): study protocol for a randomized controlled trial

BackgroundPatients with chronic autoimmune thyroiditis have impaired health-related quality of life. The thyroid gland has a high selenium concentration, and specific selenoprotein enzyme families are crucial to immune function, and catalyze thyroid hormone metabolism and redox processes in thyroid cells. Previous randomized controlled trials have found that selenium supplementation decreases thyroid-disease-specific antibody levels. We hypothesize that selenium might be beneficial in the treatment of chronic autoimmune thyroiditis.Methods/DesignThe CATALYST trial is an investigator-initiated randomized, blinded, multicentre clinical trial of selenium supplementation versus placebo in patients with chronic autoimmune thyroiditis. Inclusion criteria: age ≥18 years; serum thyroid peroxidase antibody level ≥100 IU/ml within the previous 12 months; treatment with levothyroxine and written informed consent. Exclusion criteria: previous diagnosis of toxic nodular goitre, Graves’ hyperthyroidism, postpartum thyroiditis, Graves’ orbitopathy; previous antithyroid drug treatment, radioiodine therapy or thyroid surgery; immune-modulatory or other medication affecting thyroid function; pregnancy, planned pregnancy or breastfeeding; allergy towards any intervention or placebo component; intake of selenium supplementation >55 μg/day; inability to read or understand Danish or lack of informed consent. The trial will include 2 × 236 participants. The experimental intervention and control groups will receive 200 μg selenium-enriched yeast or matching placebo tablets daily for 12 months. The experimental supplement will be SelenoPrecise®. The primary outcome is thyroid-related quality of life assessed by the Thyroid Patient-Reported Outcome (ThyPRO) questionnaire. Secondary outcomes include serum thyroid peroxidase antibody concentration; serum triiodothyronine/thyroxine ratio; levothyroxine dosage; adverse reactions and serious adverse reactions and events.DiscussionIn this pragmatic trial, participating patients follow their usual treatment at their usual hospitals. In order to collect high-quality data on the clinical course and quality of life, and to minimize missing data, an elaborate trial management system has been designed. 12 months intervention duration was selected in consideration of the primary outcome, thyroid-related quality of life.Trial registrationClinicalTrials.gov ID: NCT02013479.

Selenium status and hair mercury levels in riverine children from Rondônia, Amazonia

ObjectiveRiverine communities in Rondônia State are exposed to high selenium (Se) content in their diet because of the high-selenium soils identified in the Amazon. However, the Amazonian population has a high mercury (Hg) exposure because this metal accumulates in the soil. Because children are more vulnerable to Hg toxicity, the aim of this study was to evaluate and correlate Se status and hair Hg levels in riverine children (aged 3–9 y) living in two different locations in Rondônia State: Demarcação area (DA) and Gleba do Rio Preto (GRP). MethodsSe levels were assessed using hydride generation quartz tube atomic absorption spectroscopy; total hair Hg levels were assessed using cold vapor atomic absorption spectrometry. Dietary intake was evaluated through a 24-h food record and a food frequency questionnaire. ResultsForty-two children participated in this study. Eighty-four percent of the children from DA showed low plasma Se. Conversely, all children from GRP presented plasma Se levels above the reference values. Forty-five percent of the children from DA presented low erythrocyte levels, and 55% of the children from GRP showed concentration in erythrocyte above the reference values. The mean Se intake was 41.8 μg/d in DA and 179.0 μg/d in GRP. High hair Hg levels were observed in children from both the DA and GRP (3.57 ± 1.86 and 6.24 ± 5.89, respectively). ConclusionsChildren from both riverine communities are likely to present altered Se status according to their dietary intake. Additionally, these children are highly exposed to Hg, mainly through fish consumption, and the toxicity of this metal may cause metabolic damage.

Copper electrodeposition from sulfate solutions—Effects of selenium

The upshot of the presence of selenium in the electrolytic solution as an impurity over a concentration range of 0 to 1000mgdm−3 during the electrodeposition of copper from sulfate solutions has been investigated in the present study. Higher concentrations of selenium (>50mgdm−3) in the copper sulfate solutions significantly reduce the current efficiency and quality of the copper electrodeposits and increase the energy consumption of the electrodeposition process. Cyclic voltammetric studies revealed that selenium, when present in the solution, affects the deposition and dissolution behavior of the cathodic copper significantly. The presence of selenium in the electrolytic bath polarizes the cathode and decreases the cathodic and anodic currents considerably. In the presence of higher concentrations of selenium (~1000mgdm−3), the co-reduction of selenium was observed. The order of relative diffraction intensity was changed from (111)>(200)>(220) to (111)>(220)>(200) without affecting the preferred plane of crystal growth of copper (111). However, distinguished peaks of selenium were observed for the deposits obtained at an individual impurity concentration of 1000mgdm−3 in the solution in support of the observation made during polarization studies. Scanning electron micrographs revealed that the presence of selenium in the acidic copper sulfate bath develops a non-uniform and porous structure with indistinct grain boundaries instead of a compact and smooth deposit as obtained from pure solutions. At higher selenium concentrations, the copper deposits are induced with cracks and ultimately give rise to powdery deposits. The effect of selenium is worse when copper electrodeposition is carried out at 60°C.

Isoform-specific Binding of Selenoprotein P to the β-Propeller Domain of Apolipoprotein E Receptor 2 Mediates Selenium Supply

Sepp1 supplies selenium to tissues via receptor-mediated endocytosis. Mice, rats, and humans have 10 selenocysteines in Sepp1, which are incorporated via recoding of the stop codon, UGA. Four isoforms of rat Sepp1 have been identified, including full-length Sepp1 and three others, which terminate at the second, third, and seventh UGA codons. Previous studies have shown that the longer Sepp1 isoforms bind to the low density lipoprotein receptor apoER2, but the mechanism remains unclear. To identify the essential residues for apoER2 binding, an in vitro Sepp1 binding assay was developed using different Sec to Cys substituted variants of Sepp1 produced in HEK293T cells. ApoER2 was found to bind the two longest isoforms. These results suggest that Sepp1 isoforms with six or more selenocysteines are taken up by apoER2. Furthermore, the C-terminal domain of Sepp1 alone can bind to apoER2. These results indicate that apoER2 binds to the Sepp1 C-terminal domain and does not require the heparin-binding site, which is located in the N-terminal domain. Site-directed mutagenesis identified three residues of Sepp1 that are necessary for apoER2 binding. Sequential deletion of extracellular domains of apoER2 surprisingly identified the YWTD β-propeller domain as the Sepp1 binding site. Finally, we show that apoER2 missing the ligand-binding repeat region, which can result from cleavage at a furin cleavage site present in some apoER2 isoforms, can act as a receptor for Sepp1. Thus, longer isoforms of Sepp1 with high selenium content interact with a binding site distinct from the ligand-binding domain of apoER2 for selenium delivery.

Effect of pulsed electric fields (PEF) on accumulation of selenium and zinc ions in Saccharomyces cerevisiae cells.

The cultures of Saccharomyces cerevisiae were treated with pulsed electric fields (PEF) in order to obtain a maximum accumulation of selenium and zinc ions (simultaneously) in the biomass. The following concentrations: 100μgSe/ml and 150μgZn/ml medium were assumed to be optimal for the maximum accumulation of these ions, that is 43.07mg/gd.m. for selenium and 14.48mg/gd.m. for zinc, in the cultures treated with PEF. At optimal PEF parameters: electric field strength of 3kV/cm and pulse width of 10μs after the treatment of 20-h culture for 10min, the maximum accumulation of both ions in the yeast cells was observed. Application of PEF caused the increase of ions accumulation by 65% for selenium and 100% for zinc. Optimization of PEF parameters led to the further rise in the both ions accumulation resulting in over 2-fold and 2.5-fold higher concentration of selenium and zinc.

Effect of selenium supplementation in pig feed on slaughter value and physicochemical and sensory characteristics of meat

AbstractThe aim of the study was to examine the assimilability of organic and inorganic selenium supplied as an additive to pig feed. The influence of both selenium forms on pig slaughter value as well as on the physicochemical and sensory characteristics of meat was also examined (experiment I). An attempt to establish the distribution of selenium in the body of experimental fatteners was made (experiment II). Experiment I was performed on 20 carcasses of crossbred pigs of (Polish Large White × Polish Landrace) × Duroc genotype and experiment II was carried out on 45 samples of longissimus and semimembranosus muscles taken from fatteners of the same genotype (PLW × PL × Duroc). The results obtained indicated that selenium supplementation in the diet had no impact on slaughter performance, meat quality and most physicochemical and sensory characteristics of meat. Selenium was found to have no significant effect on meat colour. The meat water holding capacity (WHC) was lower in the group of pigs fed organic selenium. The highest selenium concentration was found in the semimembranosus muscle of fatteners receiving the inorganic selenium additive.

Investigating the Effects of Se Solid Phase Substitution in Jarosite Minerals Influenced by Bacterial Reductive Dissolution

Jarosite minerals (AB3(TO4)2(OH)6) are iron hydroxysulfate minerals that can readily incorporate trace metals into their mineral structure. A range of metals can be incorporated into the jarosite structure, including oxyanions such as selenate (SeO42−). Selenium is a micronutrient, but is toxic in relatively low doses. Selenium is present in aqueous systems in its two oxyanion forms: selenate and selenite (SeO32−). The tetrahedral sulfate coordination site can be completely substituted for selenate in jarosite minerals (NaFe3(SO4)x(SeO4)2-x(OH)6). Bacteria have been observed to reduce Se oxyanions to both more reduced forms and insoluble elemental Se. This is a pathway for selenium immobilization at contaminated sites. This experiment investigates the reductive dissolution of two Se-jarosites (solid substitution containing high and low selenium concentrations) in the presence of Shewanella putrefaciens CN32. It was observed that both Fe(III) and selenate were metabolically reduced and released into solution through jarosite dissolution . Selenate was also found to be incorporated intracellularly and reduced to particulate Se which was released upon cell lysis. Compared to the abiotic samples, enhanced dissolution was found with both the live and dead bacteria treatments.

Potential of Pleurotus ostreatus mycelium for selenium absorption.

The aim of this study was to evaluate the effect of high selenium (Se) concentrations on morphophysiological and ultrastructural properties of Pleurotus ostreatus. Mycelium growth was good in media enriched with 5.0, 10.0, and 20.0 mg L−1 of Se, concentration of 500.0 mg L−1 strongly inhibited growth, and 1000.0 mg L−1 was the minimum inhibitory concentration. Contrary to thin-walled, hyaline, branched, and anastomized hyphae with clamp-connections in the control, at Se concentrations of 100.0 and 500.0 mg L−1, they were noticeably short, frequently septed and branched, with a more intensive extracellular matrix, and without clamp-connections. At high Se concentrations, hyphae with intact membrane, without cellular contents, with a high level of vacuolization, and with numerous proteinaceous bodies were observed. Biomass yield ranged between 11.8 g L−1, in the control, and 6.8 g L−1, at an Se concentration of 100.0 mg L−1, while no production was detected at a concentration of 500.0 mg L−1. Se content in the mycelia reached a peak (938.9 μg g−1) after cultivation in the medium enriched with Se at the concentration of 20.0 mg L−1, while the highest absorption level (53.25%) was found in the medium enriched with 5.0 mg L−1 Se.

A novel function of lamb and pork: Different effects of lamb and pork consumption on thyroid hormone levels and energy metabolism of Sprague–Dawley rats

Different effects of lamb and pork consumption on thyroid hormone levels and energy metabolism of rats were investigated. Three diets, a lamb meat diet (LD), a pork meat diet (PD) and control casein diet (CD) were isocaloric (15.5kJ/g dry matters). Rats in the PD group had higher serum selenium concentrations (P<0.05) and liver 5′-deiodinase activities (P<0.05), caused by higher selenium contents in pork meat (PM). As a result, PM consumption increased serum tri-iodothryonine (T3) concentrations (P<0.05) and decreased serum thyroxine (T4) concentrations compared to casein and lamb meat (LM). Compared to casein and LM powder, PM powder had higher total content of glutamic acid, leucine, aspartic acid, serine, and alanine (48.94 vs 44.24 vs 44.78), which led to higher serum TBG concentrations (P<0.05) in the PD group. Compared to casein, PM powder had higher total content of leucine and isoleucine (9.87 vs 9.21; 5.12 vs 4.74), LM powder had lower content of leucine (8.14 vs 9.21) leading to higher serum albumin concentrations in the PD group (P<0.05) and lower ones in the LD group (P<0.05). Consequently, the PD group had lower serum concentrations of free T4 (FT4) and free T3 (FT3) (P<0.05), thus significantly decreasing the energy expenditure of rats, while the LD group had higher serum FT3 concentrations (P<0.05), thus significantly increasing the energy expenditure. These were deduced from the different changes of Na,K-ATPase activities of liver and skeletal muscle (P<0.05), oxygen consumption rates (OCRs) (P<0.05) and rectal temperature, especially on day 13 (P<0.05) and the body weights (P<0.05) in the PD or LD group. We concluded that PM or LM consumption, with different amino acids composition, had different effects on the energy metabolism of rats by multiple-step regulation of THs.

Application of hanging copper amalgam drop electrode for voltammetric determination of selenium content in fruiting bodies of selected mushrooms

A high-sensitivity method based on the CSV with the differential pulse step performed at the hanging copper amalgam drop electrode (HCADE) has been applied for selenium trace determination in selected mushrooms. The HCADE is characterised by simple handling, regeneration facility as well as very good repeatability and reproducibility of the surface. For synthetic solution LOD of Se(IV) as low as 0.25 nM (0.02 μg · kg−1) at preconcentration time (120 s) could be obtained with RSD = 2.3% (n = 5). The accuracy of the method was validated by analysis of certified reference materials (BCR 185R). Fruiting body caps of 12 selected macrofungi species from Basidiomycetes have been investigated. The selenium content determined in the dry matter of mushroom samples was equal to 0.49 ‒ 11.7 mg · kg−1. The highest concentration of selenium was found in Boletus edulis and the lowest one in Laetiporus sulphureus on-plant growing pathogen.