Biotechnology and Bioinformatics (1+1)

2.2.3.2. Antifreeze protein genes

Production of cold resistant fish variety is useful for establishing aquaculture industry in the temperate region, where water gets frozen during winter. The gene responsible for imparting cold resistance was cloned from winter flounder (Pseudopleuronectes americanus), which lives in the polar sea. This species avoids freezing of its blood even at –7°C temperatures by producing a set of anti-freeze proteins (AFP).

• AFP are produced in the liver and exported to the blood stream.

• When produced at high concentration (10-20 mg/ml), AFP inhibits the growth of ice crystal formation in the blood, which helps to protect fish from freezing.
• Following the discovery of AFP and the isolation of their genes, efforts have been made for developing cold resistant variety.
• Fletcher et al. (1986) showed that AFP injection to seawater-acclimatized rainbow trout lowered the freezing point of the whole fish in proportion to the circulating anti-freeze protein concentration.
• This experiment revealed the feasibility of providing freeze protection to animals by transgenesis (Fletcher et al., 1988).