Uptake and incorporation of mercury into mercury-binding proteins of gills of Mytilus edulis as a function of time

Individuals of Mytilus edulis (collected from Sequim Bay, Washington, in April and August, 1980) were exposed to 5 g l^-1 mercury as HgCl₂ for 28 d. Gill mercury accumulation, mercury incorporation into the soluble fraction and low molecular weight, mercury-binding proteins of gills, and induction of these mercury-binding proteins were determined as a function of time. Short-term mercury uptake rates of excised gills were also determined for mussels sampled at intervals during exposure. Gill mercury accumulation occurred in three phases, represented by net uptake phases initially (up to Day 4) and toward the end of the exposure (Days 15 to 28), and an intermediate stable phase (Days 4 to 15). The stable phase was associated with induction of the predominant mercury-binding proteins and mercury incorporation into the proteins. After Day 15, the mercury-binding proteins were saturated and spillover of mercury into high molecular weight proteins had occurred. This was associated with saturation of the soluble fraction, increases of mercury on particulate fractions, and a loss of the ability of gills to maintain stable mercury concentrations. Mercury uptake rates of gills were not affected by the 28 d exposure of the whole organism.