Utilization of a Rapid DNA-Based Assay for Molecular Verification of Channel Catfish, Blue Catfish, F₁ Hybrids, and Backcross Offspring at Several Life Stages

Abstract

The F₁ hybrid offspring of female channel catfish Ictalurus punctatus × male blue catfish I. furcatus contain many desirable traits for commercial production, such as enhanced growth and increased survivability. Hybrids can be produced through pond spawning (although at a low efficiency), but hybrid catfish cannot always be readily distinguished from channel catfish, especially at early life stages. The present research was designed to produce a rapid DNA-based test for the identification of hybrid catfish. Channel catfish and blue catfish genomic regions were amplified by polymerase chain reaction (PCR)using common primers for the follistatin (Fst) and hepcidin antimicrobial protein (Hamp) genes, and fragment length polymorphisms between the two species caused by ancestral insertions and deletions were resolved by agarose electrophoresis. The Fst amplicons were 348 and 399 base pairs (bp), while the Hamp amplicons were 222 and 262 bp from channel catfish and blue catfish, respectively. The mitochondrial cytochrome c oxidase 1 (Mtco1) gene was also differentially amplified from each species by using species-specific primers to enable determination of the maternal parent species. The DNA preparation technique provided sufficient genomic DNA to test several life stages. The PCR products were successfully amplified from genomic DNA isolated from embryos at 1, 2, or 5 d after fertilization; from fry 2 d after hatching; from the blood and barbels of juveniles and adults; and from fresh, frozen, and cooked fillet samples. The results from this assay were available as soon as 24 h after receipt of sample. This assay will be useful for management of hybrid populations and postharvest detection of hybrid catfish products.