Selenium in Plants: Uptake, Functions, and Environmental Toxicity

Läuchli, André

doi:10.1111/j.1438-8677.1993.tb00774.x

Cited by 198 publications

(126 citation statements)

References 110 publications

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“…Unless specifically noted, all concentrations in diets reported in the text and tables are in wet weight, but can be converted to dry weight by multiplying by 3.59 for comparison. The concentrations in the diets are within the ranges found occurring in plants at contaminated sites (Lauchli, 1993;Vajpayee et al, 1999) and in forms known to occur within plants (Ge et al, 1996). These diets, blue in color, provided excellent contrast with the white eggs, white larvae, and yellow-brown puparia of the insects, greatly facilitating counts.…”

Section: Methodsmentioning

confidence: 71%

Developmental Responses of a Terrestrial Insect Detritivore, Megaselia scalaris (Loew) to Four Selenium Species

2005

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Abstract. Megaselia scalaris (Loew) (Diptera: Phoridae) is an important and ubiquitous terrestrial detritivore that consumes both animal and plant material. Because both plants and animals convert selenium pollutants into various forms, the relative toxicities of ecologically relevant concentrations of sodium selenate, sodium selenite, seleno-L-methionine, and Se-(methyl) selenocysteine hydrochloride to larvae were assessed in diet bioassays. In addition, ovipositional preferences of adults and developmental effects on the eggs and larvae were measured. With chronic exposure selenocysteine was the most toxic of the selenium species to the larvae (LC 50 : 83 lg/g wet weight), followed by seleno-L-methionine (LC 50 : 130 lg/g), selenate (LC 50 : 258 lg/g), and selenite (LC 50 : 392 lg/g). Ovipositing females did not discriminate between the highest treatment concentrations of any of the pollutants as compared to the controls, indicating a lack of avoidance behavior. Larval development time was significantly increased with exposure to selenate at 100 lg/g wet weight and above, selenite at 300 lg/g and above, and at 50 lg/g and 25 lg/g and above for seleno-L-methionine and selenocysteine respectively. Pupal development was not affected by any of the selenium treatments. Significant differences between male and female adult eclosion times were observed, with females eclosing later than males as selenium concentrations increased. Significant decreases in larval survival relative to controls occurred at the lowest treatment tested (100 lg/g) for both selenate and selenite and at 100 lg/g for seleno-L-methionine, and 50 lg/g for selenocysteine. The population level implications of lack of avoidance of contaminated food, and the effects of increased development times, reduced survivorship, and non-synchronized male and female emergence are discussed.

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Section: Methodsmentioning

confidence: 71%

Developmental Responses of a Terrestrial Insect Detritivore, Megaselia scalaris (Loew) to Four Selenium Species

2005

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“…Selenium uptake and the conversion of inorganic selenium to organic molecules such as selenocysteine and selenomethionine in plants and algae have been reviewed by Lauchli (41). Further incorporation of selenocysteine into selenoproteins has not been yet reported, despite the fact that selenium-dependent GPX activity was reported in C. reinhardtii and the marine diatom Thalassiosira psedonana (21,42).…”

Section: Discussionmentioning

confidence: 99%

A Selenoprotein in the Plant Kingdom

Fu¹,

Wang²,

Eyal³

et al. 2002

Journal of Biological Chemistry

154

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Selenoproteins that contain the rare amino acid selenocysteine in their primary structure have been identified in diverse organisms such as viruses, bacteria, archea, and mammals, but so far not in yeast or plants. Among the most thoroughly investigated families of selenoenzymes are the animal glutathione peroxidases (GPXs). In the last few years, genes encoding GPX-like homologues from Chlamydomonas and higher plants have been isolated, but, unlike the animal ones, all of them have cysteine (rather than selenocysteine) residues in their catalytic site. In all organisms investigated that contain selenoproteins, selenocysteine is encoded by a UGA opal codon, which is usually a stop codon. We report here that, in Chlamydomonas reinhardtii, the cDNA-cloned sequence of a GPX homologue contains an internal TGA codon in frame to the ATG. Specific mRNA expression, protein production, and enzyme activity are selenium-dependent. Sequence analysis of the peptides produced by proteolytic digestion, performed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), confirmed the presence of a selenocysteine residue at the predicted site and suggest its location in the mitochondria. Thus, our data present the first direct proof that a UGA opal codon is decoded in the plant kingdom to incorporate selenocysteine.

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“…Little is known about the role of selenium in the remaining living kingdom. Plants appear not to depend on selenoenzymes, yet they contain numerous low molecular weight selenocompounds of nutritional, pharmacological, and toxicological interest (Läuchli, 1993;Neuhierl et al, 1999). Together with bacteria, which may also 'dissimilate' bioavailable selenite to elementary selenium (Garbisu et al, 1995), plants, by assimilation of inorganic selenium, certainly contribute to the maintenance of the geo-ecological selenium homeostasis that is equally important for livestock and human health (National Research Council, 1983).…”

Section: Discussionmentioning

confidence: 99%

Selenium in Biology: Facts and Medical Perspectives

Köhrl¹,

Brigelius‐Flohé²,

Böck³

et al. 2000

Biological Chemistry

245

143

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Several decades after the discovery of selenium as an essential trace element in vertebrates approximately 20 eukaryotic and more than 15 prokaryotic selenoproteins containing the 21 st proteinogenic amino acid, selenocysteine, have been identified, partially characterized or cloned from several species. Many of these proteins are involved in redox reactions with selenocysteine acting as an essential component of the catalytic cycle. Enzyme activities have been assigned to the glutathione peroxidase family, to the thioredoxin reductases, which were recently identified as selenoproteins, to the iodothyronine deiodinases, which metabolize thyroid hormones, and to the selenophosphate synthetase 2, which is involved in selenoprotein biosynthesis. Prokaryotic selenoproteins catalyze redox reactions and formation of selenoethers in (stress-induced) metabolism and energy production of E. coli, of the clostridial cluster XI and of other prokaryotes. Apart from the specific and complex biosynthesis of selenocysteine, selenium also reversibly binds to proteins, is incorporated into selenomethionine in bacteria, yeast and higher plants, or posttranslationally modifies a catalytically essential cysteine residue of CO dehydrogenase. Expression of individual eukaryotic selenoproteins exhibits high tissue specificity, depends on selenium availability, in some cases is regulated by hormones, and if impaired contributes to several pathological conditions. Disturbance of selenoprotein expression or function is associated with deficiency syndromes (Keshan and Kashin-Beck disease), might contribute to tumorigenesis and atherosclerosis, is altered in several bacterial and viral infections, and leads to infertility in male rodents.

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Selenium in Plants: Uptake, Functions, and Environmental Toxicity

Cited by 198 publications

References 110 publications

Developmental Responses of a Terrestrial Insect Detritivore, Megaselia scalaris (Loew) to Four Selenium Species

Developmental Responses of a Terrestrial Insect Detritivore, Megaselia scalaris (Loew) to Four Selenium Species

A Selenoprotein in the Plant Kingdom

Selenium in Biology: Facts and Medical Perspectives

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