Uptake of organic material by aquatic invertebrates—II. Accumulation of amino acids by the bamboo worm, Clymenella torquata

Abstract

1. 1. The maldanid worm, Clymenella torquata, is capable of removing glycine, lysine, phenylalanine and valine from dilute solution in the surrounding medium. 2. 2. The rate of uptake of these compounds from solutions of the order of 10 −6 moles/l depends on the compounds and is linear with time for at least 30 min. 3. 3. This uptake represents an accumulation of amino acid by the worm since the concentration per unit volume of body water is approximately four to ten times greater than the concentration in the medium after a 15 min exposure to an ambient solution. 4. 4. This process takes place across the body wall and does not require the participation of the digestive tract. Removal or ligation of the head or tail of the organism does not modify the rat of uptake. The rate of uptake under given conditions is an exponential function of the wet weight of the organism. 5. 5. The uptake process for these compounds exhibits kinetics which are similar to those for an enzyme-catalyzed process, indicating that uptake is probably limited by an adsorptive step at higher concentrations. 6. 6. The rate of accumulation of amino acids is independent of the oxygen tension of the medium for periods as long as 24 hr. 7. 7. Radioactivity appears in other compounds in the worms and labeled carbon dioxide can be recovered from the medium. Hence at least a portion of the amino acid taken up from solution enters functional metabolic pools. 8. 8. Samples of interstitial water, from the mud flat where the worms are abundant, were collected and free amino acids were estimated. Five estimates of ninhydrin-positive material in an extract of such samples range from 60 to 104 μmoles/l expressed as amino acid equivalents. An inventory of neutral and acidic amino acids in one sample totalled 74 μmoles/l. 9. 9. The oxygen consumption of Clymenella was measured and found to be 0·09 ml O 2/hr per g wet weight for 100 mg animals. 10. 10. Calculations, based on the amino acid levels found in the environment and the rate of uptake measured in the laboratory indicate that the amino acids obtained by the process under natural conditions may represent a significant supplement to food obtained by other methods.