Basic interactions of Aspergillus niger with Se(IV)

Filamentous fungus Aspergillus niger is commonly found on decaying vegetation or in indoor environment and has a number of uses, including application in bioremediation. Hence, the basic interactions of this common mould with selenite were studied, including biovolatilization, bioaccumulation and toxicity effects of selenite on fungal growth. The fungal strain, originally isolated from noncontaminated soil, was cultivated under aerobic conditions on liquid cultivation media with concentration of Se(IV) 19 or 27 mg.l-1 during 25 days. The fungal growth in the presence of selenite was not inhibited when compared to control, only the sporulation was reduced. The concentration of Se(IV) in liquid medium decreased rapidly within first ten days to 1 mg.l-1. However, according to results from the 25th day of cultivation, the concentration of total selenium in medium did not change significantly and only negligible amount of selenium (less then 1%) was bioaccumulated. That indicates some biotransformation of selenite into other selenium species. During the cultivation, up to 21% of total amount of selenium was transformed into volatile derivatives (biovolatilization) by filamentous fungus A. niger.

Chromatographic Determination of Total Selenium in Biofortified Allium sp. following Piazselenol Formation and Micro-Solid-Phase Extraction

Herein, a method based on selective piazselenol formation is applied for total selenium determination in biofortified Allium species. Piazselenol is formed by reacting Se(IV) with an aromatic diamine, namely 4-nitro-1,2-phenylenediamine, in acidic medium. Samples were digested in a nitric acid/hydrogen peroxide open system, followed by selenate reduction in hydrochloric acid. Reaction conditions were optimized in terms of pH, temperature, reaction time, and other auxiliary reagents for interference removal, namely, EDTA and hydroxylamine. For the extraction of the selectively formed 4-nitro-piazselenol, micro-solid-phase extraction (μSPE) was applied, and the analysis and detection of the corresponding complex was performed by HPLC coupled with DAD. An external standard calibration curve was developed (R2 = 0.9994) with good sensitivity, and was used to calculate the total selenium content from several Allium plants material, with good intermediate precision (RSD% < 16%). The accuracy of the method was evaluated using both, a comparison with an accepted reference method from our previously published data, as well as three certified reference material with recoveries between 84–126%. The limit of detection was determined to be 0.35 μg/g (in solids) and 1.1 μg/L (in solution), while the limit of quantification was 1.07 μg/g and 3.4 μg/L (in solution). Using the proposed method, selenium content can be quickly and accurately determined in several types of samples. In addition, this study present experimental conditions for overcoming the interferences that might be encountered in selenium determination using piazselenol.

Effects of Selenium Fertilizer Application on Yield and Selenium Accumulation Characteristics of Different Japonica Rice Varieties

In this study, three japonica rice varieties—Nanjing 9108, Jiahua 1 and Wuyunjing 29—were supplied with different levels of nano-foliar selenium fertilizers (0, 40 and 80 kg Se ha−1) under field conditions. Their rice yield and absorption, accumulation, transportation and utilization of selenium were studied to find suitable selenium-rich rice cultivars and optimal selenium supply levels, while providing references for the development of selenium-rich rice. On an average basis, the Nanjing 9108, Jiahua 1 and Wuyunjing 29 yielded 8755 ± 190, 8200 ± 317 and 9098 ± 72.7 kg ha−1, respectively. The selenium content in polished rice of the three rice varieties is between 0.210 and 0.933 mg kg−1. When 40 g Se ha−1 nano-selenium fertilizer was used, the selenium accumulation in the shoots of Nanjing 9108, Jiahua 1 and Wuyunjing 29 was, respectively, 11.4 g Se ha−1, 12.3 g Se ha−1 and 12.2 g Se ha−1, and when 80 g Se ha−1 selenium fertilizer was applied, the total selenium accumulation of three rice varieties was, respectively, 2.45, 1.75 and 2.40 times that of 40 g Se ha−1 selenium fertilizer. No evident diversity was observed in the selenium transport coefficient and the apparent utilization rate of selenium among the three varieties. The three rice varieties in this experiment had a strong selenium enrichment capacity, and they could be planted as selenium-enriched and high-yield rice varieties. Further, the amount of selenium fertilizer should not exceed 40 g Se ha−1.

2-Hydroxy-4-Methylselenobutanoic Acid (HMSeBA) Promote Follicle Development By Antioxidant Pathway in Gilts

Background Dietary 2-hydroxy-4-methylselenobutanoic acid (HMSeBA) supplementation can exert antioxidant effects in poultry, pigs and weaned pigs. However, it is unknown whether HMSeBA could improve the development of follicle by anti-oxidize effects in gilt. This study was conducted to evaluate the effects of dietary HMSeBA supplementation on the follicle development in gilt. A total of 36 gilts were randomly fed the control diet (CON, negative control), Na2SeO3 diet containing 0.3 mg Se/kg (positive control) or the HMSeBA diet containing 0.3 mg Se/kg from weaning to the 19th day after the second estrus. In another study, the effect of HMSeBA on the cells viability, proliferation, release of 17βestradiol (E2 ) and antioxidant capacity were investigated in the mouse ovarian granulosa cells in vitro. Results Results showed that HMSeBA group increased the average daily body weight gain (ADG) and decreased the ratio of feed: gain during day 120 to 176 in gilts ( P < 0.05). The selenium (HMSeBA and Na 2 SeO 3 ) increased the weight of uterine at the third estrus. There was no effect of HMSeBA on the number of large follicles (diameter >5mm), but HMSeBA decreased the gene expression of growth differentiation factor-9 ( GDF-9 ) and bone morphogenetic protein-15 ( BMP-15 ) in cumulus-oocyte complexes (COCs). HMSeBA group increased the total selenium content in serum ( P < 0.05) and liver ( P < 0.01) and tended to increase the total selenium content in ovary ( P = 0.08). HMSeBA group decreased the malondialdehyde (MDA) concentration in the serum, liver and ovary ( P < 0.05), increased the total antioxidant capacity (T-AOC) in the liver, thioredoxin reductase (TrxR) in the ovary ( P < 0.05) and increased the activity of GPx in the serum, liver and ovary ( P < 0.05). Na 2 SeO 3 supplementation decreased MDA and increased the T-AOC in liver, increased the T-SOD and TrxR in the ovary compared with control. At the transcription level, HMSeBA group increased the glutathione peroxidase 2 ( GPx2 ) and TrxR1 ( P < 0.05) expression in the liver, and increased the GPx1 expression ( P < 0.05) in the ovary of gilts compared with Na2SeO3 treatment. Besides, HMSeBA group increased the expressions of superoxide dismutase 1 ( SOD1 ) and Thioredoxin l ( Trx1 ) in the liver. In vitro experiment, HMSeBA improved granulosa cells’ proliferation and E2 secretion ( P < 0.05). HMSeBA and Na 2 SeO 3 both increased the T-AOC and decreased MDA in granulosa cells in vitro. Meanwhile, HMSeBA increased T-SOD, GPx, glutathione reductase (GR) and TrxR activity in granulosa cells in vitro. In addition, HMSeBA up-regulated SOD2 and GPx1 gene expression in the granulosa cells in vitro.Conclusion These results demonstrate directly, HMSeBA was more conducive to absorption and storage of selenium in the liver and ovary in gilt, and beneficial to exert the effect of HMSeBA on the antioxidant function in the liver and ovary of gilt. Moreover, HMSeBA has stronger antioxidant capacity in granular cells in vitro , which is more conducive to promoting follicle development. Therefore, the new type of organic selenium, HMSeBA, could be potentially useful for the control of reproductive processes in gilt.

Inherited Selenocysteine Transfer RNA Mutation: Clinical and Hormonal Evaluation of 2 Patients

<b><i>Introduction:</i></b> Iodothyronine deiodinases are selenoproteins with the amino acid selenocysteine (Sec) introduced into the position of a TGA stop codon by a complex machinery involving tRNA^[Ser]Sec when a cis-acting Sec-insertion sequence element is present in the 3′ end of the mRNA. Recently, a variant in the <i>TRU-TCA1-1</i> gene encoding for tRNA^[Ser]Sec was reported, which resulted in reduced expression of stress-related selenoproteins. The proband presented with multisystem symptoms, euthyroid hyperthyroxinemia, and selenium deficiency. Here, we describe 2 new members of a family harboring the same tRNA^[Ser]Sec variant. <b><i>Case Presentation:</i></b> A 13-year-old patient was seen for Hashimoto’s disease with high FT3 (4.6 pg/mL, normal range 2–4.2 pg/mL) and normal FT4 and TSH concentrations. He had no clinical complaints. During a 6-year clinical and hormonal follow-up, the index patient was not treated, FT3 decreased, FT4 increased, and serum TSH stayed in the normal range resulting in a euthyroid hyperthyroxinemia. Reverse T3 concentration was significantly increased at the last visit (19 years and 4 months). At the last evaluation, the total selenium level was low (91 μg/L, normal range 95–125). DNA sequencing identified a germinal homozygous variant (C65G) in the <i>TRU-TCA1-1</i> gene. During follow-up, no additional clinical symptom was observed in the absence of any treatment. The same germinal tRNA^[Ser]Sec variant was identified at heterozygous state in his father, who had normal thyroid function tests except a moderately increased reverse T3 concentration, with increased total selenium (143 μg/L) level. In both patients, the expression of stress-related selenoprotein GPX3 was in the low-normal range (168 and 180 IU/L, respectively, normal range: 150–558 IU/L). We did not find any significant biological abnormalities evocative of other selenoprotein deficiencies. <b><i>Discussion/Conclusion:</i></b> We report on 2 members of a family with a variant in the <i>TRU-TCA1-1</i> gene encoding for tRNA^[Ser]Sec. Our study suggests that this tRNA^[Ser]Sec variant is not exclusively causative of disruption in selenoprotein synthesis.

Analytical Problems in Separation of Selenomethionine and Its Oxidative Product in HILIC HPLC

Selenomethionine (SeMet) is one of the main selenium forms in foods and supplements. Determining its presence in natural food samples creates difficulties due to possible oxidation processes. The objective of this study was to evaluate the possible degradation of SeMet in water extracts of green teas, one of the most consumed beverages worldwide. Such a medium has not been investigated at this time. The HILIC-HPLC MS/MS method with different stationary phases was used to achieve the satisfactory separation of SeMet and selenomethionine oxide (SeMetO). The addition of dithiothreitol and β-mercaptoethanol, recommended to ensure that SeMet is kept in the reduced form, was also evaluated. The best separation was achieved using the zwitterionic HILIC stationary phase coupled to mass spectrometry and MeOH with water (85/15, v/v) as the eluent. Extraction was done with hot water with the addition of β-mercaptoethanol. The infusions prepared from Lung-Ching teas (from the Zhejiang Province in China) contained the highest concentration of selenium in a typical cup of tea (12.5–17.3 µg L−1). For other tested teas it decreased in the following order: Yunnan > Dilmah > Lipton. For Lung-Ching teas, the sum of concentrations of SeMet and SeMetO corresponded to about 46–63% of the total selenium in their extracts.

Speciation and Determination of Selenium Oxyanions at the Drinking Water Pollution Concentration Levels

The research on selenium presence in water resources has revealed the need to determine the respective aquatic species. As selenium oxyanions SeO32− (SeIV) and SeO42− (SeVI) predominate in natural waters, their determination is essential, mainly due to different ecotoxicity properties, as well as to different removal options from relevant-polluted waters. This study focuses on the SeO32−/SeO42− speciation/separation and determination through the selective adsorption of SeO32− only onto specific iron oxy-hydroxides (FeOOHs). For this purpose, the laboratory prepared FeOOHs examined along with the commercially available relevant material (Bayoxide), which was found to present optimum results for the speciation of selenium oxyanions, at the low concentration range 10–100 μg/L, using a dose of 0.5 g/L of adsorbent and gently stirring for 30 min at the usually encountered pH value of 7.3 ± 0.2. Moreover, the relevant experiments showed that the other major ions Cl−, HCO3−, NO3−, SO42−, Ca2+, Mg2+, Na+, possibly found in most natural waters at the concentration range 0–200 mg/L, as well as silicon, total organic carbon (TOC) of natural organic matter (NOM) and iron at the concentration range 0–50 mg/L, 0–5 mg/L and 0–1 mg/L, respectively, did not interfere with the selective adsorption of Se(IV). Furthermore, the most important advantage of this selective speciation method is its implementation/combination with all commonly applied analytical methods for the determination of total selenium.