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Oxygen limitation and tissue metabolic potential of the African fish Barbus neumayeri: roles of native habitat and acclimatization.

Martínez ML, Raynard EL, Rees BB, Chapman LJ - BMC Ecol. (2011)

Bottom Line: Individuals were collected from two sites differing dramatically in concentration of dissolved oxygen (DO), Rwembaita Swamp (annual average DO 1.35 mgO2 L(-1)) and Inlet Stream West (annual average DO 5.58 mgO2 L(-1)) in Kibale National Park, Uganda, and reciprocally transplanted using a cage experiment in the field, allowing us to maintain individuals under natural conditions of oxygen, food availability, and flow.Fish were maintained under these conditions for four weeks and sampled for growth rate and the activities of phosphofructokinase (PFK), lactate dehydrogenase (LDH), citrate synthase (CS), and cytochrome c oxidase (CCO) in four tissues, liver, heart, brain, and skeletal muscle.Acclimatization to the low DO site resulted in lower growth rates, lower activities of the aerobic enzyme CCO in heart, and higher activities of the glycolytic enzyme PFK in heart and skeletal muscle.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biology, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada. mmartinezgarcia@laurentian.ca

ABSTRACT

Background: Oxygen availability in aquatic habitats is a major environmental factor influencing the ecology, behaviour, and physiology of fishes. This study evaluates the contribution of source population and hypoxic acclimatization of the African fish, Barbus neumayeri, in determining growth and tissue metabolic enzyme activities. Individuals were collected from two sites differing dramatically in concentration of dissolved oxygen (DO), Rwembaita Swamp (annual average DO 1.35 mgO2 L(-1)) and Inlet Stream West (annual average DO 5.58 mgO2 L(-1)) in Kibale National Park, Uganda, and reciprocally transplanted using a cage experiment in the field, allowing us to maintain individuals under natural conditions of oxygen, food availability, and flow. Fish were maintained under these conditions for four weeks and sampled for growth rate and the activities of phosphofructokinase (PFK), lactate dehydrogenase (LDH), citrate synthase (CS), and cytochrome c oxidase (CCO) in four tissues, liver, heart, brain, and skeletal muscle.

Results: Acclimatization to the low DO site resulted in lower growth rates, lower activities of the aerobic enzyme CCO in heart, and higher activities of the glycolytic enzyme PFK in heart and skeletal muscle. The activity of LDH in liver tissue was correlated with site of origin, being higher in fish collected from a hypoxic habitat, regardless of acclimatization treatment.

Conclusions: Our results suggest that the influence of site of origin and hypoxic acclimatization in determining enzyme activity differs among enzymes and tissues, but both factors contribute to higher glycolytic capacity and lower aerobic capacity in B. neumayeri under naturally-occurring conditions of oxygen limitation.

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Effects of collection site and acclimatization treatment on citrate synthase activities in tissues of the African cyprinid Barbus neumayeri. Samples were collected from Inlet Stream West or Rwembaita Swamp and acclimatized in the normoxic stream site (open bars) or the hypoxic swamp site (filled bars) for four weeks. P values are from two-way ANOVAs with site of origin and acclimatization treatment as main effects (see Methods). Error bars represent one SEM and sample sizes for each tissue are given above the bars.
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Figure 3: Effects of collection site and acclimatization treatment on citrate synthase activities in tissues of the African cyprinid Barbus neumayeri. Samples were collected from Inlet Stream West or Rwembaita Swamp and acclimatized in the normoxic stream site (open bars) or the hypoxic swamp site (filled bars) for four weeks. P values are from two-way ANOVAs with site of origin and acclimatization treatment as main effects (see Methods). Error bars represent one SEM and sample sizes for each tissue are given above the bars.

Mentions: Maximal enzyme activities representing tissue glycolytic capacity (PFK and LDH) and aerobic capacity (CS and CCO) are shown in Figure 1, Figure 2, Figure 3 and Figure 4. Exploratory data analysis indicated that body mass was positively related to brain LDH activity (P = 0.0048), and hence mass-corrected activities are shown for this enzyme only (Figure 2). In general, acclimatization site proved to be more important than collection site (origin) in determining the maximal activities of these enzymes. Acclimatization to the low oxygen habitat resulted in higher PFK activities in heart and skeletal muscle (F1,76 = 4.514, P = 0.037 and F1,76 = 9.035, P = 0.004, respectively, Figure 1). Conversely, fish acclimatized to the hypoxic swamp had lower heart CCO activity (F1,77 = 3.974, P = 0.049, Figure 4). Trends toward higher glycolytic enzyme activities and lower aerobic enzyme activities were observed in other tissues (e.g., muscle CS, Figure 3), but these were not statistically significant largely due to the high variation in enzyme activity determinations. Site of origin was significantly related to liver LDH activity: fish collected from the hypoxic swamp habitat had higher activities than fish from the normoxic stream habitat (F1,76 = 5.534, P = 0.021, Figure 2). The interaction between site of origin and acclimatization site was not significant for any tissue enzyme activity.


Oxygen limitation and tissue metabolic potential of the African fish Barbus neumayeri: roles of native habitat and acclimatization.

Martínez ML, Raynard EL, Rees BB, Chapman LJ - BMC Ecol. (2011)

Effects of collection site and acclimatization treatment on citrate synthase activities in tissues of the African cyprinid Barbus neumayeri. Samples were collected from Inlet Stream West or Rwembaita Swamp and acclimatized in the normoxic stream site (open bars) or the hypoxic swamp site (filled bars) for four weeks. P values are from two-way ANOVAs with site of origin and acclimatization treatment as main effects (see Methods). Error bars represent one SEM and sample sizes for each tissue are given above the bars.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3037293&req=5

Figure 3: Effects of collection site and acclimatization treatment on citrate synthase activities in tissues of the African cyprinid Barbus neumayeri. Samples were collected from Inlet Stream West or Rwembaita Swamp and acclimatized in the normoxic stream site (open bars) or the hypoxic swamp site (filled bars) for four weeks. P values are from two-way ANOVAs with site of origin and acclimatization treatment as main effects (see Methods). Error bars represent one SEM and sample sizes for each tissue are given above the bars.
Mentions: Maximal enzyme activities representing tissue glycolytic capacity (PFK and LDH) and aerobic capacity (CS and CCO) are shown in Figure 1, Figure 2, Figure 3 and Figure 4. Exploratory data analysis indicated that body mass was positively related to brain LDH activity (P = 0.0048), and hence mass-corrected activities are shown for this enzyme only (Figure 2). In general, acclimatization site proved to be more important than collection site (origin) in determining the maximal activities of these enzymes. Acclimatization to the low oxygen habitat resulted in higher PFK activities in heart and skeletal muscle (F1,76 = 4.514, P = 0.037 and F1,76 = 9.035, P = 0.004, respectively, Figure 1). Conversely, fish acclimatized to the hypoxic swamp had lower heart CCO activity (F1,77 = 3.974, P = 0.049, Figure 4). Trends toward higher glycolytic enzyme activities and lower aerobic enzyme activities were observed in other tissues (e.g., muscle CS, Figure 3), but these were not statistically significant largely due to the high variation in enzyme activity determinations. Site of origin was significantly related to liver LDH activity: fish collected from the hypoxic swamp habitat had higher activities than fish from the normoxic stream habitat (F1,76 = 5.534, P = 0.021, Figure 2). The interaction between site of origin and acclimatization site was not significant for any tissue enzyme activity.

Bottom Line: Individuals were collected from two sites differing dramatically in concentration of dissolved oxygen (DO), Rwembaita Swamp (annual average DO 1.35 mgO2 L(-1)) and Inlet Stream West (annual average DO 5.58 mgO2 L(-1)) in Kibale National Park, Uganda, and reciprocally transplanted using a cage experiment in the field, allowing us to maintain individuals under natural conditions of oxygen, food availability, and flow.Fish were maintained under these conditions for four weeks and sampled for growth rate and the activities of phosphofructokinase (PFK), lactate dehydrogenase (LDH), citrate synthase (CS), and cytochrome c oxidase (CCO) in four tissues, liver, heart, brain, and skeletal muscle.Acclimatization to the low DO site resulted in lower growth rates, lower activities of the aerobic enzyme CCO in heart, and higher activities of the glycolytic enzyme PFK in heart and skeletal muscle.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biology, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada. mmartinezgarcia@laurentian.ca

ABSTRACT

Background: Oxygen availability in aquatic habitats is a major environmental factor influencing the ecology, behaviour, and physiology of fishes. This study evaluates the contribution of source population and hypoxic acclimatization of the African fish, Barbus neumayeri, in determining growth and tissue metabolic enzyme activities. Individuals were collected from two sites differing dramatically in concentration of dissolved oxygen (DO), Rwembaita Swamp (annual average DO 1.35 mgO2 L(-1)) and Inlet Stream West (annual average DO 5.58 mgO2 L(-1)) in Kibale National Park, Uganda, and reciprocally transplanted using a cage experiment in the field, allowing us to maintain individuals under natural conditions of oxygen, food availability, and flow. Fish were maintained under these conditions for four weeks and sampled for growth rate and the activities of phosphofructokinase (PFK), lactate dehydrogenase (LDH), citrate synthase (CS), and cytochrome c oxidase (CCO) in four tissues, liver, heart, brain, and skeletal muscle.

Results: Acclimatization to the low DO site resulted in lower growth rates, lower activities of the aerobic enzyme CCO in heart, and higher activities of the glycolytic enzyme PFK in heart and skeletal muscle. The activity of LDH in liver tissue was correlated with site of origin, being higher in fish collected from a hypoxic habitat, regardless of acclimatization treatment.

Conclusions: Our results suggest that the influence of site of origin and hypoxic acclimatization in determining enzyme activity differs among enzymes and tissues, but both factors contribute to higher glycolytic capacity and lower aerobic capacity in B. neumayeri under naturally-occurring conditions of oxygen limitation.

Show MeSH
Related in: MedlinePlus