Second‐round interlaboratory comparison of hepatic ethoxyresorufin‐O‐deethylase activity in white sucker (Catostomus commersoni) exposed to bleached‐kraft pulp mill effluent

Abstract

Livers were collected from six male and six female white sucker (Catostomus commersoni) at both a bleached‐kraft pulp mill effluent (BKME)‐exposed site and a reference site during the 1992 spring spawning migration. A semistandardized methodology for 7‐ethoxyresorufin‐O‐deethylase (EROD) analysis was proposed that featured similar physical and chemical conditions yet allowed for different instrumentation and techniques. Postmitochondrial supernatants (PMSs) were analyzed for EROD activity by 14 laboratories, and repeat EROD analyses were performed within one laboratory to estimate within‐laboratory variability. All laboratories found significantly higher levels of EROD activity (approximately threefold) in males from the BKME‐exposed site; only 5 of 14 laboratories found significantly higher levels in exposed females. Data from three labs were dropped from the analysis because of outlying values. The mean coefficient of variation (C.V.) for the remaining 11 laboratories was 34.7%, which was not significantly different from the C.V. determined for six analyses by one technician (28.4%). The mean C.V. for five analysts within one laboratory was significantly lower (16.4%) than either of the former values. There was no difference in absolute values or the variability of microplate and conventional EROD assay data. Analysis of Bradford and Lowry protein data showed that both assays have low variability (C.V.s = 16.8 and 17.4%, respectively); these two techniques produced very similar estimates of protein content. Immunochemical analysis demonstrated a significant correlation existed among microsomal P4501A concentration and EROD activity. Sources of commercially available resorufin standard were tested, and the mean molar extinction coefficient was 54.0 ± 1.1 cm−1 mM−1.

Concentration dependence of in vitro biotransformation rates of hydrophobic organic sunscreen agents in rainbow trout S9 fractions: Implications for bioaccumulation assessment

“…The protein concentration of pool A was determined by the Bradford () assay, and that of pool B was measured by Peterson's modification of the Lowry method (Sigma‐Aldrich ) using bovine serum albumin (fraction V) as the standard. Previous investigations have shown that these 2 techniques produce very similar estimates of protein content (van den Heuvel et al ). Total lipids were determined in the S9 pools using the Bligh and Dyer () method.…”

In vivo and in vitro toxicity of decabromodiphenyl ethane, a flame retardant

“…Hepatocyte EROD and UDPGT activities were used as the indicators of toxicity. Cell EROD activity was measured according to a modified method of Klotz et al (1984), Hodson et al (1991), and van den Heuvel et al (1995). The final concentration of 7‐ethoxyresorufin in Tris‐buffer was 2.5 μM, and of NADPH 250 μM.…”

Aquatic Ecosystem Health Assessment of the Athabasca River Mainstem Oil Sands Area Using White Sucker Health

“…Detailed fish health assessments of individual fish included assessment of age, growth, condition, liver size and gonad size relative to body weight, and abnormalities assessments, all EEM endpoints used in the monitoring plans [4], [5]. Measurement of hepatic mixed-function oxygenase (MFO) activity as an indicator of exposure to pulp mill effluents, PCBs, PAHs, and some pesticides using ethoxyresorufin-O-deethylase (EROD) methods of Van den Heuvel et al [6] and abnormalities for histological evaluation was conducted [7]. Liver samples in white sucker were collected for liver tumor assessments while muscle and liver tissue were collected for contaminant (PAH's and alkylated PAH's) analyses [8].…”