BIOFORTIFICATION OF HORTICULTURAL CROPS WITH SELENIUM

Selenium (Se) is a naturally occurring element, structurally resembling with Sulphur, lying in group 6 of the periodic table. It is an essential micronutrient, required for proper functioning of many biological processes like hormone formation, immune system, hair growth, muscular movements and reproduction and helps in defense against many diseases like viral infections, Keshan’s diseases and arthritis, as it is important component of selenoproteins and enzymes like glutathione peroxidase. Low selenium level in human body can lead to various diseases and disorders. To fulfill selenium dietary intake, selenium enriched diet is necessary. Plants are the main source of human diet. Plants are fortified with selenium by adding different forms of selenium through different methods. They uptake or absorb selenium through Sulphur assimilation pathway and store it into the tissues in either organic or inorganic form. Till now much research has been carried out in production of se-fortified crops. This review paper is aimed at reviewing recent studies which have been done on biofortification of horticultural plants with selenium, like fruits and vegetables, which contribute a major portion of human diet.

Rola selenu w patogenezie chorób tarczycy

Diseases of the thyroid gland are an increasing epidemiological problem in Poland. These are primarily disorders associated with insufficient production of hormones, referred to as hypothyroidism. For the proper functioning of the gland, it is necessary to correctly supplement micronutrients, among which one of the most important is selenium. The aim of the study is to present the role of selenium in thyroid diseases. This element is part of many enzymes from the selenoproteases group. Insufficient supply leads to a reduction in the synthesis of tetradodotyronin 5-deiodinase and antioxidant enzymes. In the case of selenium deficiency, the thyroid hormone formation process is disturbed and the destructive effect of oxidative stress on gland cells is increased. Adequate supplementation of this microelement is essential for the proper functioning of the thyroid gland.

Imprinting Effects of Proline Containing Dipeptides (Proline-Glycine, Proline-Leucine, Proline-Valine and Their Retro Variants) in Tetrahymena. Evolutionary Conclusions

Proline-glycine, proline-leucine and proline-valine dipeptides and their retro variants were used in the experiments to study the effects of pretreatment (imprinting) in Tetrahymena, by investigating fluorescein isothiocyanate (FITC)-conjugated peptide binding. The protozoan organism could differentiate between the proline-dipeptides containing different partner amino-acids and between the dipeptides having the amino acids in reversed positions. The effect of imprinting was positive or negative and this was dependent on the type of the partner amino acid and on its position. Pro-Gly and Pro-Leu induced positive imprinting (elevated FITC-dipeptide binding) and Pro-Val induced negative imprinting (decrease of FITC-peptide binding). There was positive imprinting induction in two cases for the retro FITC-peptide and in one case for the FITC-conjugate of the imprinter peptide itself. The highest positive imprinting (almost 60% increase) was induced by Pro-Gly for FITC-Gly-Pro. Considering earlier—chemotaxis—experiments, the results of the present—binding—studies run parallel with the physiological effects. The experiments call attention to the sharp differentiating ability of small peptides at a unicellular level, that could have some role in the selection of molecules for hormone formation, during evolution.

Exogenous free iodotyrosine inhibits iodide transport through the sequential intracellular events

Nasu M, Sugawara M. Exogenous free iodotyrosine inhibits iodide transport through the sequential intracellular events. Eur J Endocrinol 1944;130:601–7. ISSN 0804–4643 We describe a new function of exogenous iodotyrosine as a regulator of iodide transport. Porcine thyroid follicles in culture were preincubated with 0–20 μmol/l monoiodotyrosine or diiodotyrosine (DIT) in the presence of bovine thyrotropin (TSH) for 24 h; these iodotyrosines inhibited iodide uptake in a dose–response manner. Extracellular [125I]DIT was actively transported to the thyroid follicle in the presence of TSH or (Bu)2cAMP. Inhibition of iodide uptake by iodotyrosine required preincubation with iodotyrosine in the presence of TSH; without TSH, iodotyrosine was ineffective. Follicles preincubated with DIT for 24 h inhibited TSH-mediated cAMP production, which is an important signal for iodide transport. Inhibition of iodide uptake and cAMP generation by iodotyrosine was negated characteristically by 3-nitro-l-tyrosine, an inhibitor of iodotyrosine deiodinase, or by methimazole, an inhibitor of thyroid peroxidase. Our findings suggest that iodotyrosine regulates iodide transport through the following sequential intracellular events: TSH-dependent iodotyrosine transport into the thyroid cell; deiodination of iodotyrosine and release in iodide; iodine organification by the peroxidase system; inhibition of cAMP generation by organified iodine; and inhibition of iodide transport. Thus, exogenous iodotyrosine can serve as an inhibitor of thyroid hormone formation only when TSH is present M Sugawara, Wadsworth VA Hospital (11 IM), Wilshire and Sawtelle Blvds, Los Angeles, CA 90073, USA