| 1. |
- Balk, Lennart, et al.
(författare)
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Widespread episodic thiamine deficiency in Northern Hemisphere wildlife
- 2016
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Many wildlife populations are declining at rates higher than can be explained by known threats to biodiversity. Recently, thiamine (vitamin B-1) deficiency has emerged as a possible contributing cause. Here, thiamine status was systematically investigated in three animal classes: bivalves, ray-finned fishes, and birds. Thiamine diphosphate is required as a cofactor in at least five life-sustaining enzymes that are required for basic cellular metabolism. Analysis of different phosphorylated forms of thiamine, as well as of activities and amount of holoenzyme and apoenzyme forms of thiaminedependent enzymes, revealed episodically occurring thiamine deficiency in all three animal classes. These biochemical effects were also linked to secondary effects on growth, condition, liver size, blood chemistry and composition, histopathology, swimming behaviour and endurance, parasite infestation, and reproduction. It is unlikely that the thiamine deficiency is caused by impaired phosphorylation within the cells. Rather, the results point towards insufficient amounts of thiamine in the food. By investigating a large geographic area, by extending the focus from lethal to sublethal thiamine deficiency, and by linking biochemical alterations to secondary effects, we demonstrate that the problem of thiamine deficiency is considerably more widespread and severe than previously reported.
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| 2. |
- Engelhardt, Josefin, et al.
(författare)
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Severe thiamine deficiency in eastern Baltic cod (Gadus morhua)
- 2020
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- The eastern Baltic cod (Gadus morhua) population has been decreasing in the Baltic Sea for at least 30 years. Condition indices of the Baltic cod have decreased, and previous studies have suggested that this might be due to overfishing, predation, lower dissolved oxygen or changes in salinity. However, numerous studies from the Baltic Sea have demonstrated an ongoing thiamine deficiency in several animal classes, both invertebrates and vertebrates. The thiamine status of the eastern Baltic cod was investigated to determine if thiamine deficiency might be a factor in ongoing population declines. Thiamine concentrations were determined by chemical analyses of thiamine, thiamine monophosphate and thiamine diphosphate (combined SumT) in the liver using high performance liquid chromatography. Biochemical analyses measured the activity of the thiamine diphosphate-dependent enzyme transketolase to determine the proportion of apoenzymes in both liver and brain tissue. These biochemical analyses showed that 77% of the cod were thiamine deficient in the liver, of which 13% had a severe thiamine deficiency (i.e. 25% transketolase enzymes lacked thiamine diphosphate). The brain tissue of 77% of the cod showed thiamine deficiency, of which 64% showed severe thiamine deficiency. The thiamine deficiency biomarkers were investigated to find correlations to different biological parameters, such as length, weight, otolith weight, age (annuli counting) and different organ weights. The results suggested that thiamine deficiency increased with age. The SumT concentration ranged between 2.4-24 nmol/g in the liver, where the specimens with heavier otoliths had lower values of SumT (P = 0.0031). Of the cod sampled, only 2% of the specimens had a Fulton's condition factor indicating a healthy specimen, and 49% had a condition factor below 0.8, indicating poor health status. These results, showing a severe thiamine deficiency in eastern Baltic cod from the only known area where spawning presently occurs for this species, are of grave concern.
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| 3. |
- Ericson, Gunilla, 1955-
(författare)
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³²P-postlabelling analysis of DNA adducts in fish as a biomarker of genotoxic exposure
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The 32P-postlabelling assay was used for analysis of hydrophobic DNA adducts in fish as a biomarker of genotoxic exposure. DNA adducts were analysed in perch (Perca fluviatilis) and northern pike (Esox lucius), two relatively stationary fish species which are common in Swedish freshwater systems and along the Baltic coast. Experimental studies on time-course, dose-response and persistence of DNA adducts in liver and extrahepatic tissues of pike were performed in the laboratory. DNA adducts were readily formed in pike exposed to carcinogenic model substances. Oral exposure gave rise to higher adduct levels in both liver and intestine compared to intraperitoneal exposure. Following repeated oral exposure, adduct levels increased in a dose-related manner in liver, gills, brain and intestine, with highest levels in the intestine. No significant decrease in total adduct levels was observed in liver, gills and brain during a 78-day period after the last exposure, while adduct levels in intestine decreased to one third of the maximum value. DNA adducts in the intestine are probably removed due to a high cell turnover rate in this tissue, and may thus represent ongoing or relatively recent exposure.Perch and pike from minimally polluted sites were analysed at several occasions, including during the reproductive season for perch, with the results showing no detectable adducts, or very low levels. No adducts related to spawning season were detected in unexposed female or male perch.In a field investigation carried out in a pollution gradient of polycyclic aromatic hydrocarbons leading away from an aluminium smelter, adduct levels in liver and kidney were correlated to distance from the suspected point source and to contaminant levels in the sediment. Adduct levels in gills, spleen, blood and brain were also elevated in perch from the site closest to the smelter compared to the outermost site. Increased adduct levels in these tissues were correlated to effects on higher biological organisation levels, i.e. hepatocellular degeneration and decreased growth rate at the two innermost sites, and decreased spleen somatic index at the innermost site. Adduct levels were also increased in perch from a river with creosote-contaminated bottom sediments, indicating that potentially genotoxic compounds in the sediment were bioavailable to the fish. Exposure of perch in the laboratory to a solvent extract prepared from the contaminated sediment resulted in adduct patterns which closely resembled those obtained from field captured perch, thus verifying the origin of the genotoxic substances. Furthermore, increased DNA adduct levels in liver and intestine of feral fish from coastal waters receiving bleached kraft pulp mill effluents were detected.The results show that 32P-postlabelling analysis of hydrophobic DNA adducts in feral perch and pike can be used as a sensitive biomarker of exposure to potentially genotoxic compounds in the aquatic environment. Adduct levels in liver and several extrahepatic tissues were positively correlated to exposure concentrations. Levels of aromatic/hydrophobic DNA adducts in unexposed perch and pike can be considered as practically zero. DNA adducts thus exhibit a wide range in response, from almost zero in unexposed fish to high levels in exposed fish, which is desirable for a good biomarker.
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