Amino Acid Uptake and Metabolism by Larvae of the Marine Worm \u3ci\u3eUrechis caupo\u3c/i\u3e (Echiura), a New Species in Axenic Culture

Axenic (bacteria-free) larval cultures of the marine echiuran worm, Urechis caupo, were reliably obtained by aseptically removing gametes directly from the gamete storage organs. Trochophore larvae only removed neutral amino acids from seawater as measured by high-performance liquid chromatography (HPLC). There was no detectable uptake, as measured by HPLC, of acidic or basic amino acids. Kinetic analysis showed that the transport system for alanine in 4-day-old larvae had a Kt of 4-6 μM and a Jmax of 9-10 pmol larva-1 h-1. Following a 50-min exposure, the majority of the radio-activity (95%) from 14C-alanine was found in the trichlo-roacetic acid-soluble fraction. Very little label appeared as acid-insoluble material, and there was no detectable lipid biosynthesis from 14C-alanine. Approximately 12% of the total alanine transported was released in the form of 14CO2. Thin-layer chromatography of intracellular free amino acid pools demonstrated that aspartic acid and glutamic acid were radiolabeled from the alanine precursor. A comparison of the energy acquired from the transport of alanine, with the metabolic rate of 4-day-old larvae, revealed that 51% of the metabolic demand could be provided by the transport and complete catabolism of this single amino acid at a concentration of 595 nM in seawater. Originally published in Biological Bulletin and used with permission

Ontogenic Changes in the Rates of Amino Acid Transport from Seawater by Marine Invertebrate Larvae (\u3cem\u3eEchinodermata, Echiura, Mollusca\u3c/em\u3e)

Transport rates of amino acids were determined for larvae of different ages of the echiuran worm Urechis caupo, the gastropod Haliotis rufescens, the bivalve Crassostrea gigas, and the sea urchin Strongylocentrotus purpuratus. All larval forms showed an increase in the transport rate of amino acids during development. Trochophores of U. caupo increased their rate of net flux for each of 5 amino acids (100 nM each) by a factor of 1.6 and 2.2 during 1-3 days and 4-8 days, respectively, for two independent cultures. In H. rufescens, the maximum transport capacity (Jmax) for alanine increased 3-fold during the 24 h required for the trochophore to develop into a veliger. In C. gigas veligers, there was a 9-fold increase in the maximum transport capacity for alanine during larval development from an 80 μm to a 300 μm larva. In sea urchins, the prism-stage larvae (2-day-old) had an alanine transport system with a Kt of 1.9 μM and a Jmax of 8.1 pmol larvae -1h-1. The kinetics of alanine transport in the pluteus-stage (4-day-old) were best described by two systems (System I: Kt = 1.0 μM with a Jmax of 5.6 pmol larva -1h-1; System II: Kt = 132.0 μM with a Jmax of 8.4 pmol larva -1h-1). In larvae of C. gigas, the relationships between the rate of alanine transport and body size was described by the equation, log Jmax (pg larva-1h-1) = 1.6894(X) + (-0.5937), where X is the shell length in μm. It is illustrated that the allometric increased in respiration rates, during the growth of bivalve larvae, is matched by an ontogenic increase in amino acid transport capacity

A Scientific Name for Pacific Oysters

WOS:000447083800041International audienc

THE UPTAKE AND METABOLISM OF DISSOLVED AMINO ACIDS BY BIVALVE LARVAE

Volume: 164Start Page: 236End Page: 25

Implications of dissolved organic material in seawater for the energetics of abalone larvae Haliotis rufescens: a review

This volume contains papers presented at the First International Symposium on Abalone Biology, Fisheries and Culture held in La Paz, Mexico

Energy Metabolism During Larval Development of Green and White Abalone, Haliotis fulgens and H. sorenseni

Volume: 204Start Page: 270End Page: 27

Growth and Energy Imbalance During the Development of a Lecithotrophic Molluscan Larva (Haliotis rufescens)

Volume: 177Start Page: 237End Page: 24

Amino Acid Uptake and Metabolism by Larvae of the Marine Worm Urechis caupo (Echiura), a New Species in Axenic Culture

Volume: 176Start Page: 317End Page: 32

Coulometric measurement of oxygen-consumption during development of marine invertebrate embryos and larvae

Determining the metabolic rate of larval invertebrates from aquatic habitats is complicated by the problems of small size and the scarcity of suitable measurement techniques, In this study, coulometric respirometry (a new technique for the study of marine embryos and larvae) was used to explore several issues associated with the rate of energy use during embryonic and larval development of marine invertebrates from three phyla, Coulometric respirometry measures rates of oxygen consumption under normoxic conditions by electrochemically replacing the oxygen consumed by organisms during an experiment, This technique is based on the assumption that all electrons consumed by the anodic reactions result in the production of oxygen, We verify this assumption using direct measurements of oxygen production and show that the technique is sensitive enough (1 nmol O-2 h(-1)) to quantify the oxygen consumption of a single individual swimming freely in a relatively large volume (2 ml), Continuous measurements can span days, and embryos in the coulometric respiration chambers develop to the larval stage at normal rates of differentiation. Measurements of metabolic rates were made with the coulometric respirometer during the complete life-span of larvae of three species (asteroid, Asterina miniata; bivalve, Crassostrea gigas; echinoid, Dendraster excentricus), For these species, metabolic power equations had mass exponents near unity (0.9-1.1), showing that metabolic rate scales isometrically with mass during larval growth, Metabolic rates were independent of the concentration of larvae used in the respirometer chambers for a range of larval concentrations from 4 to 400 larvae ml(-1) (coulometric respirometer) and from 241 to 809 larvae ml(-1) (polarographic oxygen sensor), Metabolic rates were measured using coulometric respirometry and two other commonly used techniques, polarographic oxygen sensors and Winkler's titration, Polarographic oxygen sensors in small, sealed chambers (100 mu l) consistently gave the lowest values (by as much as 80%) for the asteroid, echinoid and molluscan larvae. By comparison, rates of oxygen consumption measured using coulometric respirometry and Winkler's titration (to measure the change in oxygen concentration over time) were similar and consistently higher, Although the polarographic oxygen sensor is the most widely used method for measuring the metabolism of small animals in sealed 100-1000 mu l chambers, it appears that the metabolism of some larvae is adversely affected by the conditions within these respirometers