HEPATIC METALLOTHIONEIN LEVEL AND MIXED-FUNCTION OXIDASE ACTIVITY IN FINGERLING RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) AFTER ACUTE EXPOSURE TOPULP AND PAPER-MILL EFFLUENTS
F. Gagne et C. Blaise, HEPATIC METALLOTHIONEIN LEVEL AND MIXED-FUNCTION OXIDASE ACTIVITY IN FINGERLING RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) AFTER ACUTE EXPOSURE TOPULP AND PAPER-MILL EFFLUENTS, Water research, 27(11), 1993, pp. 1669-1682
Hepatic metallothionein (MT) levels and mixed function oxidase (MFO) a
ctivity (7-ethoxyresorufin-o-deethylase or EROD) were measured in fing
erling rainbow trout (Oncorhynchus mykiss) exposed to sublethal concen
trations of 12 pulp and paper effluents, after completion of 96 h stat
ic acute lethality assays. Barring one primary-treated effluent where
MFO levels were significantly depressed and two secondary-treated effl
uents where no significant MFO induction were observed, all other effl
uents triggered significant induction of MT and EROD, regardless of mi
ll process/treatment or of effluent lethality and chemical characteris
tics. MT and EROD inductions were significant, however, at higher conc
entrations for secondary-treated effluents than for primary-treated on
es. Lethal (96 h LC50s) to sublethal (MT and EROD lowest observable ef
fect concentrations) ratios were variable and indicated that significa
nt biochemical effects were present at effluent concentrations that we
re roughly 4-33 (MT) and 3-59 (EROD) times lower than the LC50. Enzyme
induction ranged from 1.3 to 2.5-fold for MT and from 1.3 to 9.4-fold
for EROD compared to controls. Limited chemical data available sugges
t that there were indeed classes of compounds present capable of induc
ing MT or EROD. Observed patterns of MT/MFO responses also suggest tha
t contaminant interactions may have interfered with induction for some
of the effluents studied. Refinements of this combined (sub)lethal bi
oassay procedure are envisaged to determine whether it can provide an
efficient means of detecting hazardous chemicals in industrial wastewa
ters.