COMPARATIVE GENOMIC STUDIES ON SOME MARINE FISH

Abstract

This study was carried out at the Department of Genetics, Faculty of Agriculture, Ain Shams University, Shoubra El-Khama, Egypt. Morphological characteristics represened the first and obvious line for fish identification. However, consumers are not able to identify the fish species. Reliable identification of fish species is, therefore, essential for detecting and combating mislabeling in markets. DNA barcoding is one of the most widely used and effective methods for species identification, hence its conservation. It is based on the sequence diversity of a short DNA region (DNA barcode) in the genome with high inter-specific variations. The study objectives are to apply the DNA barcoding technique to three Egyptian commercial marine fish from the Red Sea to identify and compare the sampled species using COI gene sequences based on phylogeny and inter-specific genetic distance. The Three commercially important and expensive Red Sea fish samples namely, Baghbaghan (1), Nagil (2), and Kahaya (3) were successfully DNA-barcoded using COI gene sequencing. These Samples were blasted using NCBI database and resulted that the species were identified by similarity values 100 %, which indicated that species no.1(Baghbaghan), species no.2 (Nagil) and species no.3 (Kahaya) exact matches with Scarus collana, Epinephelus tauvina and Sargocentron spiniferum species, respectively. Result declares that Baghbaghan was correctly identified, while the Nagil and Kahaya were mistakenly distributed mistakenly under other names according to fish market labels. Nagil fish of 160 LE/kg was found as greasy grouper while it was similar in morphology characters to the spotted grouper in which it can be mislabeled or even used as fraud fish and sold as Nagil fish. Kahaya fish of 60 LE/kg was found as Spiny squirrelfish, while it was similar in morphology to the Blotch eye soldierfish in which it can be mislabeled. In conclusion, the DNA barcoding technique was applied to three Egyptian markets marine fish from the Red Sea labeled according to the fish market as Nagil, Kahaya, and Baghbaghan. Compared the sampled species using COI gene sequences for phylogeny and to estimating the interspecific genetic distance were done. The results showed that Baghbaghan fish was correctly identified, while Nagil and Kahaya fish were mistakenly distributed under other names according to fish market labeling. Recording the new sequences in the Barcode and GenBank databases was done to correct those species future identification. Future studies should be carried out to include more species with significant interest in the Egyptian fish market.