Abstract:
Etroplus suratensis is the State fish of Kerala which is a delicacy which has very high economic value. Water temperature is a very important factor which affect the growth of Pearlspot. There are many genes expressed at water temperature stress. The objective of the study was “Molecular cloning, characterization and functional analysis of Growth Arrest Specific gene 2 in Pearlspot (Etroplus suratensis)”. The study was carried out at the maricuture facility, CMFRI, Kochi. Growth arrest specific gene 2 is a component of the microfilament system which plays a major role in cell death and apoptosis. This was studied to be highly expressed at cell contact inhibition, serum starvation and temperature stress The growth arrest specific gene was amplified using specific primers. The GAS2 ORF was found to be a 1017 bp sequence which was translated into a 388 amino acid sequence. The predicted molecular weight of GAS2 was found to be 38.7 k.Da. and was found to have calponin homology domain and GAS2 as conserved domains. In the study, fish juveniles were exposed to 3 water temperatures 26˚C, 30˚C and 32˚C for 72 hours. The muscle, brain and liver samples were collected at 1 hour, 12 hour and 72 hour. The expression was studied in each tissue sample by real time PCR assay. The expression patterns at each temperature and each duration was compared with the expression observed in 26˚C samples maintained as controls. The GAS2 expression was found to decrease proportional to the duration of exposure in fishes exposed to 30˚C when compared to that in the control sample maintained at 26˚C. The trend was found to be reverse in fish exposed to 32˚C, the expression increased at a constant level compared to the 26˚C control. In both experiments the highest expression was observed in muscle tissue and the lowest expression was found in liver tissue. GAS2 was found to be a stress related gene which show variable expression in different water temperatures with least expression in a range of above 26˚C and below 32 ˚C.
