observed for the sulfonation of 3-OH-B[a]P and 4'-OH-PCB79. The hexachlorinated

OH-PCBs, TCPM and PCP were poor substrates for sulfonation, suggesting that this may

be one reason why these substances and structurally similar xenobiotics persist in polar

bears .

 OH-PCBs are glucuronidated with similar efficiency by channel catfish liver and

proximal intestine. There were differences in the UGT activity profile in both organs.

Both hepatic glucuronidation and intestinal glucuronidation were decreased with the

addition of a second chlorine atom flanking the phenolic group, which is an arrangement

typical of toxic OH-PCBs that persist in organisms.

 One full length UGT from catfish liver, together with a full-length UGT (identical

to the liver UGT), and a partial sequence of a different UGT from catfish intestine were

cloned. The full-length catfish UGT clone appeared to be analogous to mammalian

UGTIAl or UGTIA6.

 The anion-exchange HPLC method developed to determine UDPGA was sensitive,

reproducible and displayed good resolution for the co-substrate. The hepatic UDPGA

levels determined by this method were similar to those in other mammalian species and

higher than reported for two other fish species. This was the first time intestinal UDPGA

concentrations in any piscine species were determined; the values were similar to rat

intestine, but significantly higher than in human small intestine.