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Mount Zion, IL, United States

Lee B.-J.,Ohio State University | Jaroszewska M.,Ohio State University | Jaroszewska M.,Nicolaus Copernicus University | Dabrowski K.,Ohio State University | And 2 more authors.
Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology | Year: 2012

An interaction of two essential nutrients, thiamine and magnesium (Mg) has been documented in . in vitro and . in vivo studies in mammalian metabolism. However, the role of this association in poikilothermic vertebrates, such as fish, remains elusive. The purpose of this study was first to investigate the effects of dietary thiamine and Mg, and their interaction in lake trout and second to better understand the mechanism leading to early mortality syndrome (EMS), which is caused by a low thiamine level in embryos of many species of salmonids in the wild. Semi-purified diets (SPD) were prepared to accomplish 2. ×. 2 factorial design that were either devoid of or supplemented with thiamine mononitrate (20. mg/kg diet), magnesium oxide (700. mg/kg diet), or both. Lake trout alevins at the swim-up stage were fed for 10. wk one of the SPD diets or a commercial diet at the same rate (2.0-1.5%) based on recorded biomass. Our results showed that the concentrations of thiamine in the trunk muscle and Mg of whole body were closely associated with the dietary level of two nutrients. The interaction of low dietary Mg and thiamine resulted in apparently worsened overt symptoms of thiamine deficiency in lake trout leading to a higher mortality of fish during the seven week long trial (. P<. 0.05). The fish fed a thiamine-devoid and Mg-supplemented diet were presumed to survive longer (10. wk) than the fish fed diets devoid of both nutrients (discontinued after 7th wk due to high mortality). However, we did not observe histopathological changes in the brain and liver corresponding to thiamine concentrations in tissues. These data suggest that Mg enhanced utilization of the thiamine remaining in the fish body and its interdependence was consistent with observations in mammals. EMS severity might be worsened when Mg is deficient in parental diets (and consequently in yolk sac) and/or first feed. © 2012 Elsevier Inc.

Carter M.W.,Lake Michigan Biological Station | Carter M.W.,University of Illinois at Urbana - Champaign | Weber M.J.,Lake Michigan Biological Station | Weber M.J.,University of Illinois at Urbana - Champaign | And 4 more authors.
Journal of Great Lakes Research | Year: 2012

Smallmouth bass . Micropterus dolomieu and largemouth bass . M. salmoides in southwestern Lake Michigan use shallow, warm harbors for spawning during spring. After the reproductive period ends in early summer, catch rates from standardized sampling of smallmouth bass in harbors decrease. Fishes are presumed to use the main lake during summer but little is known about how black basses use main-lake habitat in Lake Michigan or mechanisms driving this transition. We tracked smallmouth bass (N. =. 26) and largemouth bass (N. =. 8) using radio and acoustic telemetry during 2005-2006 near North Point Marina, IL. A temperature difference persisted between inside and outside the harbor for much of May-October where harbor temperatures were generally warmer than those outside the harbor. Smallmouth bass responded to water temperature changes, inhabiting the harbor until temperatures outside the harbor approached 18.5. °C, at which time they left the harbor. Frequent temperature fluctuations of >. 3. °C occurred outside the harbor within 24-hour periods. Sudden reductions in water temperature were associated with smallmouth bass temporarily returning to the harbor until the temperature outside the harbor again approached 18.5. °C. As water cooled during fall, smallmouth bass again returned to the harbor. Largemouth bass exhibited comparatively restricted movements during this time and rarely ranged outside the harbor. Thus, home range estimates for smallmouth bass (142.6. ha) were an order of magnitude greater than those of largemouth bass (12.9. ha). Both water temperature and species played a role in determining the degree of movement outside the harbor but both black basses used the harbor as a thermal refuge. © 2012 .

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