recognize such epitopes, in order to study the different levels of UGT protein in various

tissues or in response to environmental stressors such as xenobiotic inducers or inhibitors.

The availability of such isoform-selective antibodies is lacking, even for human UGTs

(Miners et al., 2006).

 Additional samples of catfish liver and intestinal RNA should be obtained, ensuring

that the RNA is of optimal quality. After a number of isoforms have been isolated, real-

time PCR could be performed using cDNA from catfish tissues such as brain, kidney,

gills and skin to investigate the distribution of different UGT mRNAs in the channel

catfish. Other studies can be performed on genomic DNA, in order to understand the gene

locus for catfish UGT and whether differential splicing does indeed occur as in mammals.

This would also be an opportunity to identify HNF-1 binding sites which reside within

proximal upstream regulatory regions of human UGT genes (Gardner-Stephen et al.,

2005) as well as the distal enhancer module which is the site of binding of nuclear

receptors such as the glucocorticoid and the pregnane X receptor in mammalian UGTs

(Sugatani et al., 2005).