Effect of long term feeding of T-2 and HT-2 toxin contaminated diet on the glutathione redox status and lipid peroxidation processes in common carp (Cyprinus carpio L.)

Effect of sublethal T-2 (2.45 mg kg-1 feed) and HT-2 (0.52 mg kg-1 feed) toxin treatment for 4 weeks was investigated in common carp. Two groups, a control and a T-2+HT-2 toxin treated were formed. Six carps were exterminated from each group weekly. Liver samples were taken, in which reduced glutathione concentration and glutathione-peroxidase activity were measured. Free radical formation was measured by a direct reactive oxygen metabolites test, and also malondialdehyde concentration was determined. From the first week lower feed consumption and weight gain was recorded in T-2 toxin treated group, which resulted significantly lower live weight at the end of experiment. Feeding the T-2 toxin contaminated diet caused, significantly elevated glutathione concentration and glutathione-peroxidase activity during the first week. At second week the T-2 toxin loading resulted decrease in glutathione concentration and glutathione-peroxidase activity of liver as compared to the control. Although the reactive oxygen metabolite concentration was elevated in T-2 toxin treated group during the first two weeks, no significant changes were found in the MDA concentration. The results show that the biological antioxidant system was able to eliminate the harmful peroxidative effect of T-2 toxin in common carp

Prooxidant mechanisms of selenium toxicity – a review

Selenium is an essential trace element in living organisms as integral part of seleno-enzymes. However, excess amount of selenium is toxic for so-called non-accumulator plants, animals and humans. The toxicity for plants depends on the capacity of synthesis of non-protein amino acids and also their volatilization in the form of dimethylselenide, while in animals on the rate of methylation and its excretion. In vitro studies showed that there are selenium-resistant animal and human cell lines which showed altered selenium uptake. Exact mechanism of selenium toxicity remains unclear but there are many data about its prooxidant effect particularly in the form of selenite, while selenomethionine and selenocysteine are less toxic. Inorganic forms of selenium reacts with tissue thiols, such as glutathione to form seleno-trisulphides and those are reacting with other thiols to generate oxygen free radicals, such as superoxide anion. Organic diselenides are converted into selenols in presence of thiols which also results oxygen free radical generation. Another free radical hypothesis of selenium toxicosis is based on the methyl-selenide formation, which also results superoxide radicals and induce oxidative stress. Besides free radical formation selenium can have inhibitory effects on thiol proteins, for instance those which have antioxidant affect

On the allometric scaling of fatty acids in the phospholipids of metabolically active fowl tissues

In our recent studies domesticated fowl species in the range from 150 g (Japanese quail, Coturnix coturnix japonica) to 19 kg (turkey, Meleagris gallopavo) were analysed, to elucidate supposed allometric relationship of the membrane lipid fatty acids (FA). The basis of all studies was the „membranes as pacemakers of metabolism” by Hulbert (Lipids, 2007, 42, 811-819). First in the myocardium (B=-0.6), later in the avian kidney (-0.18) and lung (-0.24), as well as liver (-0.2) negative allometric scaling was found for docosahexaenoic acid (DHA). In the membrane FAs of all these tissues rather balanced polyunsaturation, negatively scaling n3 and unsaturation index and oppositely related n6 and monounsaturated FA molar proportions were described. In the lavaged avian lung surfactant phopsholipids we reported similar negative allometry for DHA. In contarst, avian brain phospholipid FA composition failed to provide body mass relation. We found unexpected results (positive allometry for n3 FAs, DHA, unsaturation index) in the m. pectoralis superficialis phospholipids during turkey ontogenesis. In all the aforementioned splanchnic organs the concentration of whole tissue malondialdehyde was also negatively related to body mass (B=-0.16, -0.05, -0.17, -0,13 in the heart, lung, kidney and liver). Results indicate a special regulatory role for DHA, in agreement with the membrane pacemaker theory, while suggest also a strong predispository and linking role for this acid and the polyunsaturated n3 FAs towards non enzymatic lipid peroxidation