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Cloning and mRNA Expression of Hepatic Deiodinase in the Channel Catfish, Ictalurus punctatus

Jennifer Wells

Objective:  To clone and sequence hepatic Type II 5' Outer Ring Deiodinase (ORD) complementary DNA (cDNA) from catfish (ictalurus punctatus) liver, in order to use this clone to study tissue expression of Type II 5' ORD in hepatic and extra helpatic tissues.

Animals:  Five catfish were harvested to obtain livers for cloning purposes.  Eleven catfish were harvested after cloning for tissue samples to use in expression studies.

Procedures:  Reverse transcription-Polymerase Chain Reaction (RT-PCR) was performed to clone the internal portion of Type II 5'ORD.  The fragment of interest was cloned into a vector and sequenced.  Northern blots were then analyzed.

Results;  An internal fragment of the Type II 5' ORD gene of approximately 600 base pairs in length was cloned using these techniques.  Northern analysis is still being perfected.

Conclusions:  A large portion of the Type II 5' ORD was definitively cloned using these techniques.  Further sequencing work is still needed to elongate the fragment.