Molecular characterization of Glutathione S-transferase in two eel species, Monopterus cuchia (Hamilton) and Monopterus albus (Zuiew)

The present investigation has been carried out for DNA isolation, sequencing, sequence analysis, tertiary structure prediction and phylogenetic analysis of Glutathione S-transferase from two freshwater synbranchid eel species of the genus Monopterus in different states of Northeast India (Assam and Manipur). Glutathione S-transferase is potentially used as a biochemical marker of aquatic pollution and they are the decisive indicators of the toxic effect. The GST gene sequences of M. cuchia is more G: C rich than M. albus and the GST gene of M. albus is more A: T rich than that of M. cuchia. The instability index (II) value of GST enzyme of the present study ranged from 49.26 to 52.67, which classifies the GST protein as unstable. The phylogenetic analysis of GST gene revealed that, M. cuchia and M. albus formed two separate clades with high bootstap separation 98% and 100% in ML and MP tree respectively clearly indicates the possibility for existence of two sub-species in M. cuchia. The MP phylogeny of GST gene also revealed genetic diversity within M. albus at 73% bootstrap separation. Some of the samples of M. albus and M. cuchia in the GST gene phylogenetic tree revealed the possibility of interbreeding or hybridization in the Monopterus species. The predicted 3D structure of GST will reveal more insights on GST activity in M. albus and M. cuchia in order to reveal the detailed detoxification mechanism freshwater eels.