Species composition of fish eggs based on the NGS analysis

Abstract

Except for a few species with unique characteristics, most of fish eggs have been difficult to be classified into the species level because of the limited comparative morphology. Using a pyrosequencing called as the next generation sequencing (NGS), lots of fish eggs can be identified into species level and the species composition analyzed. In order to know the species composition of fish eggs, we collected samples weekly from May to August during 2008 to 2010 in the coastal area of the southern sea of Korea. Anchovy (Engraulis japonicus) eggs dominated in the study area were excluded to increase the precision of identification for the other species because anchovy eggs were easily classified by the morphology; an oval shape. For the pyrosequencing, the genomic DNAs were extracted from 100 mixed eggs per the sample (total 14,200 eggs of 142 samples). The 16S rDNA of mitochondrial DNA was partially amplified and sequenced. The sequences were trimmed and analyzed by the mothur software based on the 16S rDNA reference data from the NCBI data and mine. The fish eggs were found about 60 species from the 188,602 sequences. The abundant season of fish eggs was in the end of June and in July. The dominant species were Nuchequula nuchalis, unknown species belonging to Perciformes, and Engraulidae sp. in the order of the number of sequences reads from the NGS analysis. These were more than 90% of toencing (NGS), lots of fish eggs can be identified into species level and the species composition analyzed. In order to know the species composition of fish eggs, we collected samples weekly from May to August during 2008 to 2010 in the coastal area of the southern sea of Korea. Anchovy (Engraulis japonicus) eggs dominated in the study area were excluded to increase the precision of identification for the other species because anchovy eggs were easily classified by the morphology; an oval shape. For the pyrosequencing, the genomic DNAs were ex