Turnover rates of fatty acid and amino acid in the coelomic fluid of the sea star Asterias rubens: Implications for the route of nutrient translocation during vitellogenesis

Abstract

1. 1. The turnover of fatty acid and amino acid in the coelomic fluid of the sea star Asterias rubens was quantified by intra-coelomic injection of radiolabelled oleic acid and L-leucine which had half times of 2 and 10 min, respectively.

2. 2. The molar composition of the amino acids of the cell-free coelomic fluid was determined. The total concentration of amino acids was 4.33 ± 1.93 μg/ml; the total concentration of fatty acids was 0.34 μg/ml.

3. 3. In a period of 4 weeks, 74 mg of fatty acid and 201 mg of amino acid is transferred through the coelomic fluid of a standardized 100 g animal.

4. 4. In vitro experiments allow an estimation of the apparently minor role of coelomocytes in lipid transport.

5. 5. Transport of fatty acid and amino acid through the perivisceral coelomic fluid can by far not meet the demands of the ovaries during vitellogenesis. Therefore, other systems (haemal and perihaemal) must play an important role.