SSCP ANALYSIS OF PIG MITOCHONDRIAL-DNA D-LOOP REGION POLYMORPHISM

The sequence polymorphism that occurs in the mitochondrial DNA (mtDNA) displacement (D)-loop region is useful as a cytoplasmic DNA marker. W e cloned the mtDNA D-loop regions of five breeds of pig by polymerase chain reaction (PCR) and determined their sequences. The sequence dive rsities in D-loop regions among five breeds of pig were located in the starting area of heavy-strand replication. From these sequences, we d esigned primers for PCR-mediated single-strand conformation polymorphi sm (PCR-SSCP) analysis that amplified the most polymorphic 227bp fragm ent of the D-loop region. The results of PCR-SSCP analysis clearly sho wed that four types of polymorphism (A to D) are found in Landrace (A) , Large White (A, B), Duroc (A), Gottingen miniature pig (B) and Meish an (C, D). The same polymorphisms were also detected from each porcine embryo by this method. Our results show that PCR-SSCP analysis is use ful in detecting polymorphisms in the D-loop region of pigs and pig em bryos.