Synergistic effects of dietary vitamin E and selenomethionine on growth performance and tissue methylmercury accumulation on mercury-induced toxicity in juvenile olive flounder, Paralichthys olivaceus (Temminck et Schlegel)

Abstract

An 8-week feeding trial was conducted to evaluate the synergistic effects of dietary vitamin E and selenomethionine (SeMet) on induced methylmercury (MeHg) toxicity in juvenile olive flounder Paralichthys olivaceus. Nine semi-purified diets were formulated to contain three different vitamin E levels as DL-a-tocopheryl acetate (0, 100 and 200 mg TAkg À1 diet) and three different selenium (Se) levels (0, 2 and 4 SeMet mg kg À1 diet) on the constant mercury toxicity level (20 mg MeHgkg À1 diet). Nine experimental diets, 4 ), were fed to triplicate groups of fish averaging 2.3 AE 0.04 g (mean AE SD) in the semi-recirculation system. After 8 weeks of feeding trial, vitamin E and Se showed significant effects on weight gain (WG) of fish (P < 0.05). We found that there was a clear trend of increasing WG with elevating vitamin E and Se levels in the diets. Feed efficiency (FE), specific growth rate (SGR), protein efficiency ratio (PER) and survivability exhibited a similar trend with WG. Both antioxidants had significant interaction effects on FE and PER (P < 0.05). Methylmercury concentrations in fish muscle, liver and kidney decreases in a dose-dependent manner as dietary vitamin E and Se levels increase. Interestingly, the most significant interactive effects of vitamin E and Se were found in liver tissue for depleting Hg concentrations (P < 0.05). These findings suggest that dietary vitamin E more than 100 mg TA kg À1 diet with 2 or 4 mg SeMet kg À1 -supplemented diets could have synergistic effects on growth and liver mercury bioaccumulation on MeHg-induced toxicity in juvenile olive flounder.

Evaluation of Dietary Organic and Inorganic Mercury Threshold Levels on Induced Mercury Toxicity in a Marine Fish Model

“…Normality and homogeneity of data were confirmed by Shapiro-Wilk and O'Brien tests, respectively. The data were analyzed by one-way analysis of variance (ANOVA) test followed by least significant difference (LSD) test to compare the means [2,41,44] on SAS Version 9.0 (SAS Institute, Cary, NC, USA) software program. Mean differences were considered significant when p < 0.05.…”

“…Casein 1 27.0 Fish meal 2 32.0 Wheat flour 3 18.0 Dextrin 1 4.20 Corn starch 2 3.50 Fish oil 4 6.10 Vitamin premix 5 3.00 Mineral premix 6 3.00 Cellulose 1 3.20 Hg-premix (5000 ppm) 0.00…”

“…The juvenile olive flounder (average weight 3.1 ± 0.05 g, mean ± SD) were divided randomly into nine groups according to the feeding trial, with 84 fish in each group reared in 27 tanks, each of the tanks containing 28 fish (standard stocking density of fish in 30-L water tanks) in triplicate (9 experimental groups × 3 replicates, 756 fish in total). The feeding protocol followed Moniruzzaman et al [2] with little modification. Briefly, the experimental fish were fed the diets up to ad libitum at a feeding rate of 2.5%-3.5% of wet body weight.…”

“…Eventually, the total number of fish, as well as total weight of fish, in each aquarium were numbered and weighed to obtain data on growth performance, such as percentage of weight gain (WG), specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER) and survival rate. The sampling procedure was previously described by Moniruzzaman et al [2]. Briefly, fish were removed from each tank and euthanized in tricaine methane sulfonate solution (MS 222, 0.5 g/L; Argent Chemical Laboratories, Redmount, WA, USA).…”

“…Mercury (Hg) is a naturally occurring element found in air, water, and soil [1,2]. It may exist in three chemical forms: (1) natural mercury, which may be found in liquid and gaseous states;…”