Evidence of Circadian Rhythm, Oxygen Regulation Capacity, Metabolic Repeatability and Positive Correlations between Forced and Spontaneous Maximal Metabolic Rates in Lake Sturgeon Acipenser fulvescensReportar como inadecuado




Evidence of Circadian Rhythm, Oxygen Regulation Capacity, Metabolic Repeatability and Positive Correlations between Forced and Spontaneous Maximal Metabolic Rates in Lake Sturgeon Acipenser fulvescens - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Animal metabolic rate is variable and may be affected by endogenous and exogenous factors, but such relationships remain poorly understood in many primitive fishes, including members of the family Acipenseridae sturgeons. Using juvenile lake sturgeon Acipenser fulvescens, the objective of this study was to test four hypotheses: 1 A. fulvescens exhibits a circadian rhythm influencing metabolic rate and behaviour; 2 A. fulvescens has the capacity to regulate metabolic rate when exposed to environmental hypoxia; 3 measurements of forced maximum metabolic rate MMRF are repeatable in individual fish; and 4 MMRF correlates positively with spontaneous maximum metabolic rate MMRS. Metabolic rates were measured using intermittent flow respirometry, and a standard chase protocol was employed to elicit MMRF. Trials lasting 24 h were used to measure standard metabolic rate SMR and MMRS. Repeatability and correlations between MMRF and MMRS were analyzed using residual body mass corrected values. Results revealed that A. fulvescens exhibit a circadian rhythm in metabolic rate, with metabolism peaking at dawn. SMR was unaffected by hypoxia 30% air saturation O2sat, demonstrating oxygen regulation. In contrast, MMRF was affected by hypoxia and decreased across the range from 100% O2sat to 70% O2sat. MMRF was repeatable in individual fish, and MMRF correlated positively with MMRS, but the relationships between MMRF and MMRS were only revealed in fish exposed to hypoxia or 24 h constant light i.e. environmental stressor. Our study provides evidence that the physiology of A. fulvescens is influenced by a circadian rhythm and suggests that A. fulvescens is an oxygen regulator, like most teleost fish. Finally, metabolic repeatability and positive correlations between MMRF and MMRS support the conjecture that MMRF represents a measure of organism performance that could be a target of natural selection.



Autor: Jon C. Svendsen , Janet Genz, W. Gary Anderson, Jennifer A. Stol, Douglas A. Watkinson, Eva C. Enders

Fuente: http://plos.srce.hr/



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