. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 322 W. B. JAECKLE AND D. T MANAHAN _0 24- I £ =; 1 100 ii II MET VAL LEU ILE ALA HIS GLY TYR ASN ASP GLU LYS ARG Amino Acid Figure 3. Depletion of 13 amino acids from the medium in the presence of trochophore larvae of Urechis caupo (250 larvae mr') de- termined by high-performance liquid chromatography. The rate of amino acid uptake was calculated from the first order depletion con- stant (k) (see text). The concentration of each amino acid at the start of the experiment was 100 nM: where
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 322 W. B. JAECKLE AND D. T MANAHAN _0 24- I £ =; 1 100 ii II MET VAL LEU ILE ALA HIS GLY TYR ASN ASP GLU LYS ARG Amino Acid Figure 3. Depletion of 13 amino acids from the medium in the presence of trochophore larvae of Urechis caupo (250 larvae mr') de- termined by high-performance liquid chromatography. The rate of amino acid uptake was calculated from the first order depletion con- stant (k) (see text). The concentration of each amino acid at the start of the experiment was 100 nM: where no histogram bars are presented the change in the In-transformed substrate concentrations were not statistically significant from a slope of zero. The r values lor all statisti- cally significant rates were > amino acids (His is neutral at the pH of seawater) was pmol amino acid larva"1 h"'. In the absence of lar- vae, there was no detectable change in the concentration of any amino acid in the flask. The influx of alanine equaled the net substrate flux as shown in Figure 4. The rate of influx, measured as the depletion of '4C-alanine from the medium, was pmol larva'1 h~' (r = ); the net flux of alanine, mea- sured by HPLC, was pmol larva'' h"1 (r = ). The starting substrate concentration was 207 nM. A comparison of the regressions for both these rates showed that there was no statistically significant differ- ence between these rates (VR = , [] = ). Kinetics of alanine transport A graph showing the influence of substrate concentra- tion on the rate of transport produced a rectangular hy- perbola (Fig. 5). Linear transformations (Eadie-Hofstee) were characteristic of Michaelis-Menten kinetics (Fig. 5, see inset). The kinetics of alanine transport by 4-day-old trochophores were examined for both axenic and xenic larvae (nonsibling cultures). Axenic larvae had a K, of 4 nhf for alanine and a Jmax of 9-10 pmol larva&q
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
