Liver Selenium Concentrations Research Articles

Mercury and selenium concentrations in livers and eggs of common loons (Gavia immer) from Minnesota.

Mercury and selenium act as mutual antagonists in mature birds, but their toxicity is additive or synergistic in avian embryos and immature birds. Twenty eggs and livers from 18 mature and 9 immature common loon carcasses found in Minnesota were collected. Livers and eggs were analyzed for mercury and selenium by atomic emission and atomic absorption spectroscopy. Liver mercury concentrations were significantly higher in mature loons compared to those of immature loons and eggs. Liver selenium concentrations were significantly higher in mature loons than those of immature loons, and selenium concentrations in immature loon livers were significantly higher than levels in eggs. There was a significant positive correlation between mercury and selenium in loon livers. There was a negative correlation between mercury and selenium in eggs.

Assessment of Tolerant Sunfish Populations (Lepomis sp.) Inhabiting Selenium-Laden Coal Ash Effluents: 1. Hematological and Population Level Assessment

Sunfish were collected from coal ash effluent-receiving streams and Ohio River watershed reference sites to assess the effects of exposure to low-level selenium concentrations. Selenium, copper, and arsenic concentrations were statistically higher in tissue samples from exposed fish than in reference fish. Leukopenia, lymphocytosis, and neutropenia were evident in exposed fish and were indicative of metal exposure and effect. White blood cell counts and percent lymphocyte values were significantly correlated with liver selenium concentrations. Plasma protein levels were significantly lower in exposed fish than in fish from the Ohio River, indicating that exposed fish may have been nutritionally stressed. Condition factors for fish from the ash pond-receiving streams were the same as, or lower than, those of fish from the reference sites. There was no evidence that the growth rate of fish in the receiving streams differed from that of fish in the reference streams. Despite liver selenium concentrations which exceeded reported toxicity thresholds and evidence of significant hematological changes, there were no significant differences in fish condition factors, liver–somatic indices, or length–weight regressions related to selenium.

Selenium and mercury concentrations in brood-stock walleye collected from three sites on Lake Oahe.

A decline in the walleye Stizostedion vitreum sport fishery in lower Lake Oahe, South Dakota, was documented in the early 1980s and has been attributed to poor natural reproduction and/or recruitment. Contaminants were suspected of causing low natural reproduction/recruitment in lower Lake Oahe as well as low hatchability of eggs produced from broodstock walleyes taken from lower Lake Oahe. Concentrations of dissolved selenium in the Cheyenne River, which enters lower Lake Oahe, have increased considerably over the last 15 years. To determine whether selenium concentrations contributed to the reproduction problems in the lower Lake Oahe walleye population, adult walleye were collected during spawning operations in April 1994, 1995, and 1996 to obtain tissue samples. Muscle, liver, reproductive tissue, and unfertilized eggs were analyzed with a modified fluorometric method for determining selenium concentrations in plants. These tissues were also analyzed for mercury content using cold-vapor atomic absorption. No statistical differences (p < 0.05) in selenium or mercury concentrations among sites could be determined that would explain differential walleye egg hatchability. Correlation analysis determined significant inverse associations existed between the gonadal somatic index of male walleye and gonadal tissue selenium concentrations (r = -0.41, p = 0.0012). Both walleye sexes exhibited significant inverse associations between the hepatic somatic index (HSI) and liver selenium concentrations (males r = -0.33, p = 0.0095; and females r = -0.38, p = 0.0034). Positive relationships existed for female walleye selenium concentrations in the liver and the ovaries (r = 0.37, p = 0.003) and the liver and muscle tissue (r = 0.28, p = 0.027). Mercury concentrations in walleye ovaries were positively correlated with HSI (r = 0.30, p = 0.0012), length (r = 0.36, p = 0.0046), relative weight (r = 0.36, p = 0.0054), and muscle concentrations (r = 0.49, p = 0.0001). Mercury concentrations in male walleye muscle were correlated with age (r = 0.57, p = 0.0001), length (r = 0.79, p = 0.0001), and mercury concentrations in the testes (r = 0.43, p = 0.0006).

Selenium Status in Cattle at Slaughter: Analyses of Blood, Skeletal Muscle, and Liver

Pavlata L., A. Pechova, O. Beavafi, J. Illek: Selenium Status in Cattle at Slaughter: Analyses of Blood, Skeletal Muscle, and Liver. Acta Vet. Brno 2001, 70: 277–284. The objective of the study was to assess relationships among selenium concentrations in the blood, and liver and diaphragmatic muscle tissues and the activity of glutathione peroxidase (GSHPx) in whole blood and to decide on the use of these biochemical values in the diagnostics of selenium deficiency in cattle. Samples were collected from 44 cattle at slaughter. Regression and correlation analyses yielded equations of regression lines and correlation coefficients (r) documenting significant (p < 0.01) relationships between whole blood selenium concentration on the one hand and all the other biochemical parameters under study on the other hand. The relations were expressed by the following equations and correlation coefficients: blood Se vs. liver tissue Se y = 1.20x + 31.58, r = 0.78; blood Se vs. muscular tissue Se y = 0.53x + 11.97, r = 83; blood Se vs. GSH-Px y = 8.29x – 68.77, r = 0.93. The equations were used to calculate selenium concentrations in hepatic and muscular tissues and GSH-Px activity corresponding to whole blood selenium concentration of 100 µg.l-1 and critical concentrations indicating selenium deficiency (calculated value – 10%). Poor selenium status, as assessed from blood, muscle and liver selenium concentrations, was found in 80%, 70% and 73% of the tested animals, respectively. Considering these results and the rather uniform within-herd distribution of the values we can conclude that tissue analyses are suitable for the assessment of selenium status particularly in feeder bulls and grazed beef cattle in which only minor individual differences in selenium supply can be expected. Glutathione peroxidase, diagnostics, diaphragm, beef cattle

Concentrations of cadmium, mercury and selenium in blood, liver and kidney of common eider ducks from the Canadian arctic.

We determined concentrations of selected trace elements in livers, kidneys and blood samples from common eiders (Somateria mollissima borealis) from the eastern Canadian arctic during 1997 and 1998. Concentrations of total mercury and organic mercury were generally low in the livers of these birds (less than 6 and 4 microg g(-1) dry wt, respectively). Selenium ranged between 11-47 microg g(-1) in livers. Renal cadmium concentrations were among the highest ever published for this species (range: 47-281 microg g(-1)). The regressions of log-transformed concentrations of these trace elements in blood samples on those in liver or kidney were significant (all P-values < 0.05) and positive. However, except for organic mercury (R2 = 0.83), the co-efficients of determination were low to moderate (range of R2: 0.26-0.52), suggesting poor to moderate predictive capability. Furthermore, the relationships between total mercury in blood and liver changed between 1997 and 1998, suggesting that it would not be possible to predict consistently, concentrations of mercury in blood from those in liver based on samples taken in one year. Blood samples can be used to determine concentrations of these trace elements in common eiders (and probably other sea duck species as well). The use of blood samples is especially warranted when it is undesirable to kill the animal such as when working with rare or endangered sea duck species or when the objective is to relate trace element exposure to annual survival rates. However, the predictive equations developed here should not be used to predict expected concentrations in one type of tissue from those in the other.

Organochlorine and trace element contamination in wintering and migrating diving ducks in the southern great lakes, USA, since the zebra mussel invasion

AbstractBecause of the potential for increased trophic transfer of contaminants by zebra mussels (Dreissena sp.) to higher trophic levels, we collected four species of waterfowl (n = 65 ducks) from four locations in Lake Erie, Lake St. Clair, and Lake Michigan, USA, between 1991 and 1993 for organochlorine contaminant and trace element analyses. Geometric mean concentrations of total polychlorinated biphenyls (PCBs) and p, p′‐dichlorodiphenyldichloroethylene (DDE) were 1.35 and 0.15 μg/g wet weight in lesser scaup (Aythya affinis) carcasses and were below known effect levels. Total PCBs in 80% of carcasses, however, were above the U.S. Food and Drug Administration's threshold of 3.0 μg/g lipid weight for consumption of poultry. With the exception of selenium, trace elements were also at background or no‐effect levels. Selenium concentrations in livers of 95% of lesser scaup, 90% of bufflehead (Bucephala albeola), and 72% of common goldeneye (Bucephala clangula) were in the elevated (&gt;10 μg/g dry wt) or potentially harmful range (&gt;33 μg/g dry wt). The effects of these high selenium concentrations are unknown but should be investigated further based on reproductive effects observed in field and laboratory studies of dabbling ducks and because lesser scaup populations are declining. Concentrations of total PCBs in dreissenid mussels in western Lake Erie were 10 times higher than in the upper Mississippi River but were similar to concentrations in other industrialized rivers in Europe and the United States. Metal concentrations were similar to other industrialized sites where zebra mussels have been sampled.

The effect of long-acting injectable selenium formulations on blood and liver selenium concentrations and liveweights of red deer (Cervus elaphus)

extract There is also an error in the paper by Grace et al. in the February 2000 issue of the Journal (Vol 48, 53-56, 2000) entitled: “The effect of long-acting selenium formulations on blood and liver selenium concentrations and liveweights of red deer (Cervus elaphus)”. Throughout the article, the units of measure for pasture selenium concentrations are given as “mg Se/kg DM”; the correct unit of measure is “𝛍g Se/kg DM”.

The effect of long-acting injectable selenium formulations on blood and liver selenium concentrations and liveweights of red deer (Cervus elaphus)

Aim: To evaluate the efficacy of a new long acting injectable selenium ( Se ) formulation to increase the Se status and prevent Se deficiency in red deer. Methods: Groups of weaned red deer (four stags and six hinds/group) grazing pastures containing < 30 mg Se/kg DM were injected subcutaneously with either 0.5, 1.0 or 2.0 mg Se/kg as a new formulation of BaSeO4 (Deposel Multidose), 1.0mgSe/kg of a current formulation (Deposel), or not treated. Blood Se concentrations and liveweight were measured nine times at intervals over 377 and 270 days, respectively. Results: Both formulations of Se elevated blood Se concentrations from 105 nmol/l pre-injection for at least 377 days with peak levels of 1894, 1395 and 818 nmol/l for high, medium and low doses of Deposel Multidose, respectively, at 73–141 days, and 1508 nmol/l at 73–141 days, for the medium dose of Deposel, which persisted at similar levels for the duration of the study. Deposel Multidose produced fewer and less severe subcutaneous tissue reactions than Deposel. Pastures contained 10 to 30 mg Se/kg DM. There was no significant difference in growth rate between treated and control deer.There was a significant (p <0. 01) linear relationship (y = 1.25x + 71.6, Rp2=0.86) between blood (x) and liver (y) Se concentrations in the range of 120 – 2100 nmol/l for blood concentrations, and 200 – 3000 nmol/kg for liver concentrations. Conclusion: Injections of BaSeO4in both formulations studied were effective in increasing the Se status of deer but the new formulation produced fewer and less-severe tissue reactions. Young growing red deer appear less sensitive to Se deficiency as measured by weight gain, than sheep and cattle, suggesting that reference ranges for those species are not appropriate for deer.There was a linear correlation between blood and liver selenium concentrations.

Nutritional vitamin A deficiency alters antioxidant defenses and modifies the liver histoarchitecture in rat

Oxidative stress and morphologic changes in the liver of female rats fed on a vitamin A-deficient diet for 3 months from 21 days of age were evaluated. Vitamin A restriction produced subclinical plasma retinol concentration (0.6 μmol–L) and negligible liver retinol stores, as determined by high-performance liquid chromatography, compared to the control group, which received the same diet with 4000 IU of vitamin A (8 mg retinol as retinyl palmitate) per kg of diet. Vitamin A-deficient rats had lower body weight than control rats. No change in the liver weights was observed. In the liver of rats fed the vitamin A-deficient diet, the concentrations of thiobarbituric acid-reactive substances increased by ∼50%, and the activities of catalase and glutathione peroxidase increased by 30% and 40%, respectively, compared with those fed on the control diet. Liver superoxide dismutase activity did not change. Additionally, vitamin A-deficient rats showed higher liver concentrations (μg/g tissue) of iron (316.03 ± 12.1 vs 203.12 ± 9.5) and lower concentrations of the antioxidant trace elements zinc (15.50 ± 1.03 vs 26.63 ± 0.25) and copper (2.27 ± 0.22 vs 4.25 ± 0.37) than those of control. Liver selenium concentration was not affected. Morphologically, livers from vitamin A-deficient rats showed a partial hepatic cord disarrangement and an increased number of hepatocytes in process of involution with piknotic nuclei and condensed cytoplasm. A reduced number of fat-hepatocytes distributed at random was observed. Portal spaces showed evidence of edema and a marked infiltration by mononuclear as well as polimorphonuclear cells. Loose portal connective tissue increased, as did the number of fibroblast-like cells in portal spaces. Vitamin A deprivation for 3 months decreased the liver retinol concentration associated with marked histological alterations in the organ, which could be due, at least in part, to the increase in oxidative stress. J. Trace Elem. Exp. Med. 13:343–357, 2000. © 2000 Wiley-Liss, Inc.

Dietary Selenium Reduces the Formation of Aberrant Crypts in Rats Administered 3,2′-Dimethyl-4-aminobiphenyl

Human epidemiologic studies suggest that low selenium status is associated with increased cancer risk and that selenium supplementation is associated with reduction in the incidence of several cancers, including colorectal cancer. Aromatic and heterocyclic amine carcinogens are thought to be important in the etiology of human colorectal cancer, but no information is available on the effects of selenium on aromatic amine-induced colon cancer. In order to investigate this effect, aberrant crypt foci (ACF), the putative preneoplastic lesions of colon cancer in humans and rodents, were used as a biomarker to test the hypothesis that selenium supplementation can reduce aromatic amine-induced colon carcinogenesis. Male weanling F344 inbred rats were fed a basal torula yeast selenium-deficient diet supplemented with 0, 0.1, or 2.0 mg selenium/kg diet as selenite, selenate, or selenomethionine (SeMet). Animals were fed the diets for 4 weeks and then administered 1 sc injection/week for 2 weeks of 3,2′-dimethyl-4-aminobiphenyl (DMABP; 100 mg/kg) or vehicle (peanut oil). At 12 weeks, the rats were euthanized and the colon and rectum were removed, opened longitudinally, and fixed in 70% ethanol. Glutathione peroxidase activities in erythrocytes and liver cytosol and selenium concentrations in the colon/rectum and kidney increased significantly (p< 0.05) and in a dose-dependent manner with each of the three selenium diets. No ACF were identified in vehicle-treated rats. In DMABP-treated rats, ACF frequencies decreased significantly (p< 0.05) in groups supplemented with 0.1 or 2.0 mg selenium/kg diet as selenite and selenate but not SeMet. There were no significant differences in ACF and aberrant crypts between rats fed 0.1 vs 2.0 mg selenium/kg diet. These results suggest that dietary selenium, depending on chemical form, can reduce aromatic amine-induced colon carcinogenesis.

Heavy metals in Franklin's gull tissues: Age and tissue differences

We examined the concentrations of lead, cadmium, chromium, mercury, manganese, and selenium in feathers, liver, kidney, heart, brain, and breast muscle of Franklin's gulls (Larus pipixcan) nesting in northwestern Minnesota, USA, in 1994. Between 16% (chromium) and 71% (selenium, manganese) of the variation in metal concentrations was explained by tissue and age, except for selenium and arsenic, which were only explained by tissue. Of 35 possible differences (seven metals in five tissues), 24 significant age-related differences were found in Franklin's gulls, with young generally having lower concentrations of metals in all of their tissues than adults. A notable exception was the liver; young had significantly higher concentrations of selenium, chromium, manganese, and arsenic than did adults. Three notable findings were the following: young had significantly higher concentrations of selenium, chromium, manganese, and arsenic in their liver than did adults; young had 30 times as much chromium in the liver than adults; and adults had greatly elevated concentrations of cadmium in feathers, kidney, and liver.

Significance of Amount and Form of Dietary Selenium on Blood, Milk, and Casein Selenium Concentrations in Grazing Cows

Organic selenized yeast enriched with selenoamino acids or inorganic sodium selenate (Na2SeO4) was administered per os three times weekly as a drench for 133 d to previously unsupplemented cows that were grazing low Se pastures. Treatment groups received the equivalent of 2 or 4 mg of Se/d of either supplement form. Control cows did not receive a drench. Samples of blood and milk were collected regularly throughout the trial. Selenium concentrations in blood, milk, casein, and liver and glutathione peroxidase activity in blood and liver are reported as responses per milligram of Se intake. Mean blood Se concentrations in treated cows increased steadily and, by d 133, were 4.7 to 8.8 times that in controls. Selenized yeast was 2 to 3 times more effective than was Na2SeO4, and low Se intakes were 27% more efficient per milligram of Se administered than were high Se intakes at increasing milk Se concentration. Casein Se content mirrored that of milk; among all treated and control cows and throughout the trial, the molar ratio of Se in casein as a percentage of the Se in whole milk was constant at 71 +/- 1.2%. The Se concentration in liver biopsies taken on d 133 was indicative of total Se intake during the trial and ranged from 920 to 3920 nmol of Se/kg of fresh weight. These results demonstrate the differing efficacy of organic and inorganic Se dietary supplements to increase dairy cow Se status and to enhance Se content of milk and casein.

The Chemical Form of Selenium Influences 3,2′-Dimethyl-4-aminobiphenyl-DNA Adduct Formation in Rat Colon

There is increasing evidence that selenium can protect against tumorigenesis or preneoplastic lesion development induced by chemical carcinogens. This study examined whether selenite, selenate or selenomethionine would be protective against 3,2′-dimethyl-4-aminobiphenyl (DMABP)-DNA adduct formation in the liver and colon of rats and sought to delineate the mechanism for the protective effects of the different chemical forms of selenium against aberrant crypt formation, a preneoplastic lesion for colon cancer. After injection of DMABP, two DNA adducts were identified in the liver and colon of rats. Supplementation with either 0.1 or 2.0 mg selenium/kg diet as either selenite or selenate but not selenomethionine resulted in significantly fewer (53–70%; P < 0.05) N-(deoxyguanosin-8-yl)-(deoxyguanosin-8-yl)-3,2′-dimethyl-4-aminobiphenyl (C8-DMABP)-DNA adducts in the colon but not the liver than in rats fed a selenium-deficient diet. Rats supplemented with selenomethionine had greater (P < 0.05) plasma and liver selenium concentrations and glutathione peroxidase activity than those supplemented with selenite or selenate; however, they also had more DMABP-DNA adducts. The protective effect of selenite and selenate against DMABP-DNA adduct formation apparently is not a result of alterations in plasma or liver selenium concentrations or altered glutathione peroxidase or glutathione transferase activities but may be related to differences in the metabolism of the different forms of selenium.

Correlation between prevention of cataract development by disulfiram and fates of selenium in selenite-treated rats.

We found a new pharmacological effect of disulfiram (DSF) against rat pups with cataract induced by selenite injection. The possible reactive mechanism is discussed in this present paper. Wistar male and female rats aged 13 and 30 days, and male rats aged 7 weeks were used this present study. Cataract was induced by injection of selenite (19 micromol/kg, s.c.) to 13-day old rats. The lens opacification was monitored by using the slit lamp equipped with an anterior eye segment analysis system (EAS-1000, Nidek). The selenium contents in rat organs were detected fluorimetrically. Liposomes containing DSF (DSF-liposomes) were prepared by the reverse-phase evaporation method. Rat pups were instilled 5 microl of DSF-liposomes into both eyes 4 times per day. Adult rats were administered with DSF suspensions (100 mg/kg) by nasal cannulation. The changes of plasma concentration of diethyldithiocarbamate (DDC), which was a metabolite of disulfiram, were determined by HPLC method. Intraocular treatment with DSF-liposomes prevented the onset of cataract development in rat pups injected with sodium selenite. Treatment with DSF also significantly reduced the selenium contents in plasma at 1 h post-treatment and in the eye at 96 h post-treatment. No significant differences of selenium content in liver and kidney were observed in 13-day old rats instilled with DSF-liposomes or DSF free liposomes. Cataract could not be induced in the 30-days-old rats with the same dose of selenite (19 micromol/kg) and the liver, kidney, and especially eye of the older rats had lower levels of selenium than 13-day old rats. Diethyldithiocarbamate (DDC), an active metabolite of DSF, was decreased in the plasma following a subcutaneous injection of sodium selenite. The selenium concentration in the plasma was decreased by the intranasal administration of DSF suspensions. Instillation of DSF-liposomes into the eyes of rat pups given a subcutaneous injection of sodium selenite to induce cataracts prevented the formation of cataracts. The mechanism of inhibition may have resulted from a decreased level of selenium in the eyes following the treatment with DSF. On the other hand, as it is known that the cataracts may result from selenite-induced oxidative stress in the lens, DSF and DDC may react as anti-oxidants.

The effect of Ruapehu ash on the trace element status of grazing ruminants in the Taihape District

Aims. To investigate the impact of a large (2–5 mm) volcanic ash deposition containing sulphur and selenium on the trace element status of livestock grazing affected farmland. Methods. The trace element status of lambs, cows and hinds were compared on affected properties from slaughterhouse liver samples taken prior to and following the eruption at corresponding times of the year. Liver concentrations of selenium, copper and vitamin B12 were compared. Results. There was a statistically significant elevation of liver selenium concentration in all classes of stock sampled. Contrary to expectations, liver copper concentrations did not fall in any class of stock sampled and in fact with hinds there was a statistically significant elevation. The Vitamin B12 status of lambs showed a significant reduction, which could not be attributed to any specific aspect of the composition of the ash. Conclusions. A large deposition of selenium in volcanic ash which increased pasture levels by a factor of about 10 times also increased the liver selenium concentration of livestock. A large deposition of sulphur in volcanic ash which increased soil sulphur levels by a factor of about 30 times on a yellow brown loam soil did not result in a depletion of the liver copper concentrations of livestock grazing the affected farmland. Clinical relevance. Ruapehu ash deposits increased the liver selenium concentrations of livestock but did not result in toxic levels. Large ash deposits of sulphur to the yellow brown loam soil increased soil sulphur concentrations to many times that which could be achieved economically with fertiliser but did not result in liver copper depletion of livestock.

Selenium reference ranges in New Zealand cattle

dAim. To compare serum selenium and liver selenium concentrations with whole blood concentrations in samples taken at the same time from unsupplemented cattle, and to use these comparisons to establish a reference range for use in diagnosing selenium deficiency. dMethods. Selenium was measured in concurrent whole blood, serum and liver samples obtained from cattle in unsupplemented herds in the Manawatu, Waikato and Wairarapa regions of New Zealand. The results were statistically analysed. dResults. The revised reference ranges are as follows.

Distribution of Selenium Between Plasma Fractions in Guinea Pigs and Humans with Various Intakes of Dietary Selenium

The distribution of selenium between the plasma fractions was investigated in guinea pigs fed various levels (basal, 0.5, 1.0, 2.0, 4.0, 6.0 and 8.0 mg Se/kg) of dietary selenomethionine (Semet) and in humans living in different areas of China with different selenium status. There was a corresponding increase of selenium concentration in liver, kidney, brain, testis, spleen, heart and muscle with each increase of dietary selenium, but there were no increases of glutathione peroxidase (GPX) activity in liver, brain, testis, heart or muscle in pigs fed any of the selenium levels as compared to controls fed a basal commercial diet. On a percentage distribution basis, the selenium in selenoprotein P decreased and that in the albumin fraction increased with increased dietary intakes of selenium as Semet. The ratios of selenium to albumin in either the plasma or the albumin fractions increased with each increase in dietary selenium. The greatest percentage of selenium was in the albumin fraction of Chinese living in the high selenium areas whereas the greatest amount was in the selenoprotein P fraction in subjects living in deficient and adequate areas of China. Increases in the ratios of selenium to albumin in either the plasma or the albumin fraction also occurred with increases of selenium intake of these subjects. The results indicate that the distribution of selenium in plasma fractions reflect the levels of dietary intakes of Semet.

The LEC Rat Possesses Reduced Hepatic Selenium, Contributing to the Severity of Spontaneous Hepatitis and Sensitivity to Carcinogenesis

The hepatic concentrations of copper, zinc, magnesium, calcium, and selenium were measured in LEC rats, which develop a spontaneous form of hepatitis at 3-4 months of age, and compared to trace metal concentrations in the LEA rat, its asymptomatic congenic strain. Consistent with results found by other groups, copper was found to accumulate within the liver of LEC rats to levels more than 50 times those measured in LEA rats. In addition, liver selenium concentration in LEC rats was found to be around 50% of that in LEA rats. The enzyme activity, and RNA for the selenium dependant enzyme, glutathione peroxidase, was also found to be reduced in LEC rat liver. These results indicate that hepatic selenium in the LEC rat is depleted and that, as a result of this, the capacity to protect cells from copper-induced free-radical damage is reduced.

Supplementing copper to a fish meal based diet fed to Atlantic salmon parr affects liver copper and selenium concentrations

The present experiment was conducted to study growth and tissue responses in Atlantic salmon, Salmo salar L., fed a fish meal based diet supplemented with copper (Cu). The findings of the experiment were used to evaluate the need for dietary Cu supplementation. Atlantic salmon parr, initially weighing ≊ 7.5 g, were randomly distributed among 10 tanks, with 300 fish in each tank. Duplicate groups of fish were fed a fish meal based diet containing 3.5 mg Cu kg−1, or this diet supplemented with 5, 10, 50 or 100 mg Cu kg−1 (as CuSO4*5 H2O) for 12 weeks. Growth was recorded and blood haemoglobin measured. The Cu concentrations in whole body, liver, serum and selected muscle samples were measured, as was liver selenium (Se) concentration. There were no difference in growth among the dietary treatments. There were, however, significant differences among the dietary groups in liver Cu and Se concentrations. The fish fed the diet supplemented with 5 mg Cu kg−1 had increased liver Cu concentration compared with the other groups. Similar trends were found for serum Cu concentration and whole-body Cu concentration, but these effects were not significant. Liver Cu and Se concentrations were positively correlated and liver Se concentrations were inversely correlated to dietary Cu concentration, confirming an interaction between these two elements in salmon. There may be a positive effect of a modest Cu supplementation level, and we suggest that a small amount of Cu (5–10 mg kg−1) should be added to fish meal based diets.

An epizootic of common loons in coastal waters of North Carolina: Concentrations of elemental contaminants and results of necropsies

AbstractA 1993 die‐off of common loons (Gavia immer) in the coastal waters of North Carolina was investigated with emphasis on comparing mercury, selenium, arsenic, and lead between birds from the epizootic and reference specimens. Die‐off specimens were emaciated but contained no ingested foreign bodies and no lesions suggestive of infectious disease. Results of bacteriology, virology, parasitology, and botulism testing were unremarkable. The geometric mean concentrations (wet weight) of liver mercury (10.9 ppm), and arsenic (0.96 ppm) did not differ between specimens from the die‐off and reference loons from the same area that died of other causes. The geometric mean liver selenium concentration of die‐off specimens (10.4 ppm) was significantly higher than that of reference loons. Liver lead concentrations were &lt; 0.20 ppm in all but one sample (5.83 ppm). The geometric mean mercury concentration in the primary remiges of die‐off specimens (5.44 ppm dry weight) was significantly lower than in reference birds. Liver mercury significantly correlated with liver selenium on a molar concentration basis. We interpret the range of liver mercury concentrations in birds from the epizootic, similar liver mercury concentrations in reference loons, and higher mercury concentrations in reference loon feathers as evidence that factors other than mercury were primarily responsible for the emaciation diagnosed as the cause of mortality.