Identification of cold inducible gene from polar microalgae

Abstract

Antarctic microalga, Chaetoceros neogracile was investigated to dissect the mechanism of survival in the low temperature condition. The growth of C. neogracile was compared in different culture conditions. C. neogracile was actively growing in 4℃ culture condition and the growth rate of C. neogracile under continuous light was significantly higher than the growth rate under light- dark culture condition. To identify the cold adaptive gene, a cDNA library was created from C. neogracile in 4℃ culture condition. From the cDNA library 2,057 randomly chosen expressed sequence tags(ESTs) were analyzed. Partial sequences were obtained from 2,057 individual cDNAs, and then grouped into 1,129 non-overlapping sequences, among which 968 sequences were singletons while the remainder fell into 161 clusters. The results of a BLAST search, we found interesting clones such as cold and heat shock proteins. Cold shock inducible protein from the polar microalga C.neogracile was isolated and characterized. This gene encode protein consisting of 120 amino acid residues which showed around 70~74% sequence identify with bacterial cold shock proteins. This putative cold shock protein gene is now under further investigation.