Preliminary Study on Mitochondrial DNA Cytochrome B Sequences and Genetic Relationship of Three Asian Arowana Scleropages Formosus

Mitochondrial DNA cytochrome b (cytb) gene complete sequences of golden arowana, red arowana and green arowana of Scleropages formosus were amplified with PCR technique and sequenced.The sequence length was 1141bp for three Asian arowanas which had 5 nucleotide sites substituted, among of them 4 base substitutions were transition and only 1 was transversion, all of the base substitution happened in the third locus of the codon which only 1 site caused amino acid variation. A global deficit of guanosines (G:13.7%) and approximately equal frequencies of the other three nucleotides (A: 27.8 %, C: 34.6 %, T: 23.9%) and G+C content (48.3%) was quite constant among sequences.The genetic distance of mtDNA cytb gene sequences was 0.0026-0.0035 between green arowana and the other two Asian arowana, which indicated that Asian arowana perhaps did not evolve to the level of specie. Phylogenetic trees were constructed with NJ method and MP method using arithmetic average method.The results showed that red arowana clustered with golden arowana, after clustering with green arowana.