MOLECULAR IDENTIFICATION AND CHARACTERIZATION OF FEW CRUSTACEAN ZOOPLANKTON SPECIES BY mt-COI GENE

This study was aimed to discriminate few zooplankton species dominantly grown under mass culture from wild collection, through DNA barcoding. The zooplankton was collected from a perennial lake in Ukkadam (Lat. 10.99° N and Long. 76.96° E) Coimbatore, India, for a period of three months (December 2015 – February 2016) every 2 weeks interval. They were categorized group-wise, identified species-wise and counted. A total of 14 zooplankton species belong to 12 genera with different population density were identified (average = 1072 individuals L-1). The collected samples were subjected to mass cultured by fed with phytoplankton, yeast and cow-dung separately. Zooplankton was found to be fairly grown under phytoplankton fed group followed by yeast and cow-dung. The dominant species of zooplankton observed during the mass culture, Mesocyclops leuckarti, Mesocyclops pehpeiensis and Candona candida were subjected to molecular analysis. The brine shrimp, Artemia fransciscana was used as an out group. The isolated genomic DNA (>10 kb) was amplified with a set of universal primers (LCO1490 & HCO2198) for mt-COI gene, which yield >500 bp, and the sequences showed 73-99% accuracy/ similarity with available sequences of the same and relative species in the NCBI data base. In subjected zooplankton, less numbers of identical, similar amino acids and more numbers of variable amino acids were noted when compared with Artemia. The reverse was seen when the amino acid residues of subjected zooplankton was compared among themselves without Artemia. These results indicate the fact that there was close relationship among the zooplankton. The nucleotide compositions showed >60% AT bias, which indicates the occurrence of less NUMTS gene. Divergence rate was found to be lower between the zooplankton species, suggests that they should have recently originated from a common ancestor. The zooplankton group showed more phylogenetic information when compared with the out group, A. fransciscana with clearly delineated polyphyletic tree.