Dataset Information

Swimming physiology of European silver eels (Anguilla anguilla L.): energetic costs and effects on sexual maturation and reproduction.

ABSTRACT: The European eel migrates 5,000-6,000 km to the Sargasso Sea to reproduce. Because they venture into the ocean in a pre-pubertal state and reproduce after swimming for months, a strong interaction between swimming and sexual maturation is expected. Many swimming trials have been performed in 22 swim tunnels to elucidate their performance and the impact on maturation. European eels are able to swim long distances at a cost of 10-12 mg fat/km which is 4-6 times more efficient than salmonids. The total energy costs of reproduction correspond to 67% of the fat stores. During long distance swimming, the body composition stays the same showing that energy consumption calculations cannot be based on fat alone but need to be compensated for protein oxidation. The optimal swimming speed is 0.61-0.67 m s(-1), which is approximately 60% higher than the generally assumed cruise speed of 0.4 m s(-1) and implies that female eels may reach the Sargasso Sea within 3.5 months instead of the assumed 6 months. Swimming trials showed lipid deposition and oocyte growth, which are the first steps of sexual maturation. To investigate effects of oceanic migration on maturation, we simulated group-wise migration in a large swim-gutter with seawater. These trials showed suppressed gonadotropin expression and vitellogenesis in females, while in contrast continued sexual maturation was observed in silver males. The induction of lipid deposition in the oocytes and the inhibition of vitellogenesis by swimming in females suggest a natural sequence of events quite different from artificial maturation protocols.

SUBMITTER: Palstra AP

PROVIDER: S-EPMC2923712 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature

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Swimming physiology of European silver eels (Anguilla anguilla L.): energetic costs and effects on sexual maturation and reproduction.

Palstra Arjan P AP van den Thillart Guido E E J M GEEJM

Fish physiology and biochemistry 20100901 3

The European eel migrates 5,000-6,000 km to the Sargasso Sea to reproduce. Because they venture into the ocean in a pre-pubertal state and reproduce after swimming for months, a strong interaction between swimming and sexual maturation is expected. Many swimming trials have been performed in 22 swim tunnels to elucidate their performance and the impact on maturation. European eels are able to swim long distances at a cost of 10-12 mg fat/km which is 4-6 times more efficient than salmonids. The t ...[more]

PMID: 20390348

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Project description:Gene expression analyses have been performed on brain tissue of sexually mature and immature males using microarrays. 60 eels were transferred to two independent temperature controlled recirculation water units connected to two 500 L cylindro-conical tanks (30 fish per tank) where the fish were acclimated to seawater (35 PSU salinity) over a 2 week period.Eel males in one of the seawater units were injected intramuscularly every week over a 140 day period with 2000 IU hCG/kg (human chorionic gonadotropin, Sigma–Aldrich Chemical) dissolved in 0.9% saline to induce sexual maturation. Eel males in the other recirculation unit were injected weekly over the same period with 0.9% NaCl (vehicle).At the end of the experiment, eels were anesthetized in a solution of 0.1mg/L tricaine methanesulfonate (MS-222, Sigma Aldrich) and blood samples collected into heparinized syringes. Tissues (brain, including the olfactory bulbs, telencephalon, diencephalon and mesencephalon, and gonads) were collected from sexually immature (n=12) and sexually mature males (n=12).RNA was extracted from brain tissue of a total of 24 (12 mature and 12 immature) males. For each individual, RNA was extracted separately for olfactory bulb, telencephalon and diencephalon. Because RNA concentrations of olfactory bulb, telencephalon and diencephalon were below the amount needed for microarray analysis, a separate experiment for each part of the brain was not possible. Therefore, we combined equal concentrations of olfactory bulb, telencephalon and diencephalon as a single brain sample for each individual.Microarray analysis was conducted using an European eel-specific array consisting of a total of 14,913 probes based on a large collection of high-throughput transcriptomic sequences (Pujolar et al. 2012). Probe sequences and further details on the microarray platform can be found on the GEO database under accession number GPL15124. Data was normalized using a quantile normalization procedure using R (http://www.r-project.org)

Dataset Information

Swimming physiology of European silver eels (Anguilla anguilla L.): energetic costs and effects on sexual maturation and reproduction.

Publications

Swimming physiology of European silver eels (Anguilla anguilla L.): energetic costs and effects on sexual maturation and reproduction.

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