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Aquatic Microbial Biochemistry
Published in Stanley E. Manahan, Environmental Chemistry, 2022
The major volatile selenium species emitted to the atmosphere by microbial processes in water and soil is dimethyl selenide, (CH3)2Se . (The single largest source of natural sulfur discharged to the atmosphere is the analogous sulfur compound, biogenic dimethyl sulfide, (CH3)2S , from marine sources.) The major biological selenium compound that is the precursor to dimethyl selenide formation is selenomethionine:
Feeding weaned beef calves Se-biofortified alfalfa hay as a preconditioning strategy
Published in Gary Bañuelos, Zhi-Qing Lin, Dongli Liang, Xue-bin Yin, Selenium Research for Environment and Human Health: Perspectives, Technologies and Advancements, 2019
In plants, Se is primarily incorporated into methionine as selenomethionine, and when forage is consumed by livestock, Se from selenomethionine is incorporated into selenoproteins, whose functions range from antioxidant, anti-inflammatory, and detoxification to thyroid hormone activation. Nitrogenous fertilizers, widely hailed as one of the most important advances in agricultural technology, increase biomass but dilute essential minerals like Se, emphasizing the need for Se amendments. Application of Se directly to pastures and hayfields increases forage Se concentration in a dose-dependent manner (Filley et al. 2007) and improves blood Se concentrations, animal performance, and immunity (Hall et al. 2013a, Hall et al. 2013b). The objectives of this study were to show that feeding Se-biofortified hay increases whole-blood (WB) Se concentrations, enriches the nasal microbial diversity, improves calf performance, and aids in disease prevention in the feedlot.
Aquatic Microbial Biochemistry
Published in Stanley Manahan, Environmental Chemistry, 2017
The major volatile selenium species emitted to the atmosphere by microbial processes in water and soil is dimethyl selenide, (CH3)2Se. (The single largest source of natural sulfur discharged to the atmosphere is the analogous sulfur compound, biogenic dimethyl sulfide, (CH3)2S, from marine sources.) The major biological selenium compound that is the precursor to dimethyl selenide formation is selenomethionine:
Arsenic and selenium in the plant-soil-human ecosystem: CREST publications during 2018–2021
Published in Critical Reviews in Environmental Science and Technology, 2021
Dong-Xing Guan, Zhi-Hua Dai, Hong-Jie Sun, Lena Q. Ma
The biological functions of As and Se in the environment are determined not only by their concentration, but also by their speciation (Ali et al., 2021; Li et al., 2020). For As, common species in the environment include both inorganic such as arsenite (AsIII) and arsenate (AsV), and organic such as monomethylarsonous acid, dimethylarsinous acid, arsenosugar, arsenolipid, arsenobetaine and methylated thioarsenate (Chen et al., 2020). Similarly, for Se, there are inorganic (selenate-SeVI and selenite-SeIV) and organic (selenocysteine and selenomethionine) species (Kushwaha et al., 2021). In soils, inorganic species are dominant for As (AsV and AsIII) and Se (SeVI and SeIV), which can be taken up by microbes and plants.
Understanding selenium metabolism in plants and its role as a beneficial element
Published in Critical Reviews in Environmental Science and Technology, 2019
Reshu Chauhan, Surabhi Awasthi, Sudhakar Srivastava, Sanjay Dwivedi, Elizabeth A. H. Pilon-Smits, Om P. Dhankher, Rudra D. Tripathi
Methyl-SeCys, a methylated product of SeCys, has been reported to have a vital role in prevention of mammary cancer in a rat model system (Ellis et al., 2004). A mono-methylated form of Se, methylseleninic acid (MSA) has also been shown to inhibit the growth of mouse mammary hyperplastic epithelial cells by arresting the G1 phase of the cell cycle. The effect was accompanied by a reduction in total cellular levels of cyclin D1 (Zhu, Jiang, Ganther, & Thompson, 2002). Organic forms of Se, like SeMet, methylselenol (MSe), γ-GluMeSeCys and MeSeCys, were reported to have anti-carcinogenic properties (Fernandes & Gandin, 2015). This has sparked interest in increasing and/or modifying the Se compounds in plants (Ellis et al., 2004). Several studies have reported that MeSeCys isolated from garlic and broccoli is an effective chemoprotectant in reducing the incidence of mammary and colon cancer in rats (Finley et al., 2001; Ip et al., 2000). Rayman (2008) also confirmed MeSeCys and γ-GluMeSeCys to be more effective tumor inhibitors in comparison to other Se species. Selenomethionine and MeSeCys that are produced by different plant species, grown in Se rich soil, or Se fertilized soil have shown several beneficial properties in humans e.g. prevention of different types of cancers, alleviation of thyroid disorders, improved immune system response and treatment of male infertility (Sepúlveda, Barrientos, Mahn, & Moenne, 2013; Roman, Jitaru, & Barbante, 2014). Selenium mediated induction of apoptosis of cancerous cells and inhibition of tumor angiogenesis prove that Se controls progression of early cancerous lesions (Ip, Dong, & Ganther, 2002; Lu & Jiang, 2001; Jiang, Wang, Ganther, & Lü, 2002). The proposed mechanism of Se mediated induction of apoptosis includes activation of BCL2 family proteins and caspases and arrest of cell cycle at G1 and S phase (Wallenberg, Misra, & Björnstedt, 2014). Treatment with SeIV and GS-Se-SG has been reported to induce single-strand breaks of DNA. However, SeMeSeCys, SeMet and MSA generates methylselenol has been reported to inhibit cancer either by activation of caspase-mediated apoptosis or DNA fragmentation (Jiang et al., 2002; Wallenberg et al., 2014). Jiang et al. (2002) reported that SeIV treatments induce S-phase arrest, caspase-independent DNA fragmentation and apoptosis. Selenite-mediated activation of apoptosis involves increase in the expression of phosphorylated serine/threonine kinase, JNK1 and p38 mitogen-activated protein kinase. In contrast, MSA caused G1-phase arrest, DNA fragmentation and a caspase-dependent poly (ADP-ribose) polymerase 1 cleavage, leading to apoptosis. On the other hand, SeVI has other important functionalities as to inhibit adipogenesis via transforming growth factor β1 signaling (Wallenberg et al., 2014). Similarly, other Se metabolites like GS-Se-SG, MSA, SeCys and SeMeSeCys also prevent cancer and induce apoptosis via glutathionylation of membrane protein, DNA fragmentation, cell cycle arrest at G1, inhibition of cell cycle regulators (cyclin A and D) and activation of caspases especially caspase 3 and 12 (Wallenberg et al., 2014; Figure 5).