Genetic characteristics of ricefish from Lake Poso, Central Sulawesi, Indonesia

This study determined the genetic characteristics of ricefish from Lake Poso, Sulawesi Tengah-Indonesia based on cytochrome c oxidase subunit I (COI) gene marker. We collected and analyzed 2 tissue samples from Lake Poso, about 54 sequences from GenBank, and 100 sequences from Bold taxonID of ricefishes. The two tissue samples were extracted to obtain whole genome then amplified and sequenced to obtained COI nucleotides. The nucleotide frequencies were A = 23.8%, T/U = 29.8%, C = 26.8%, and G = 19.6%. The AT content (53.85%) in the COI region of ricefish was higher than that of GC (46.2%). We identified 217 codons from two sequences of our samples. Ninety-six percent of nucleotide changes were observed at the 3rd codon position of COI sequence, but the amino acid compositions translated by COI sequences of two samples stayed the same. We identified also 170 cut positions from two sequences of our samples. The phylogenetic tree estimated by Neighbour-joining method, Blastn and Boldsystem results, and nucleotide composition indicated that the ricefish is Oryzias nebulosus. Individuals from operational taxonomic units designated as same ricefish species, supporting morphological evidence for each of these being similar species. It is suggested that the COI barcoding can be used to identify ricefish species of Oryzias.