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Fig. 1. Photomicrographs and primary data sets for protein synthesis and
respiration rate measurements of 13-day-old fed larvae of Lytechinus
pictus. (A) Photomicrograph of 13-day-old unfed and (B) fed larvae. Scale
bars, 200 µm. (C) Linear increase of [14C]alanine incorporation
into the protein pool (TCA-insoluble fraction) of 13-day-old fed larvae of
L. pictus: y=41.4(±2.71)x–68.4
(r2=0.98; P<0.001). Rates of
[14C]alanineincorporation were converted to absolute rates of
protein synthesis (ng protein individual-1 h-1) using
the change in the specific activity of [14C]alanine in the
precursor free amino acid pool (Fig. 1E), the mole-percent of alanine in
protein (7.8%; Table 1) and the mole-percent corrected molecular mass for
amino acids in protein (129.4 g mole-1; Table 1). (D) Chromatogram
of extracted free amino acid pool from 13-day-old larvae of L. pictus
separated using high performance liquid chromotagraphy (HPLC). D, aspartate;
E, glutamate; N, asparagine; S, serine; H, histidine; G, glycine; R, arginine.
Alanine was the [14C]amino acid tracer used to determine rates of
protein synthesis. (E) Specific activity of [14C]alanine in the
free amino acid pool during protein synthesis experiments with 13-day-old
larvae of L. pictus. Specific activity was measured at the specified
sampling intervals by quantifying the moles of total alanine with HPLC (as in
Fig. 1D). [14C]alanine was measured by liquid scintillation
counting of the radioactivity associated with the alanine peak fraction.
Increase of specific activity was described by the linear equation:
y=39.2(±3.85)x+279.9 (r2=0.96;
P<0.001 for ANOVA of regression slope). (F) Respiration rate of
13-day-old fed larvae of L. pictus. Each data point represents a
different respiration chamber. Respiration rate was calculated by determining
the slope of total oxygen consumption in each respiration chamber for the
known number of larvae in that chamber:
y=109.5(±8.4)x+1254 (r2=0.97;
P<0.0001), where the slope of 109.5 has units of pmol
O2 larva-1 h-1.
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