ABSTRACT
Organisms in their ambient environment are exposed to various stressor agents, such as temperature, oxygen, pH levels, salinity, UV radiation, and chemical contaminants. Each of these abiotic factors may occur alone or in combination with others, including biotic factors (e.g., growth, reproduction). Abiotic stress usually brings about protein dysfunction. In order to survive under stress, it is very important for the cell to have mechanisms to maintain proteins in their functional conformations and to prevent nonnative proteins from aggregation. Now, it is well known that heat shock proteins play an important role in protein folding, assembly, translocation, and degradation in many normal cellular processes, stabilise proteins and membrane, and can assist in protein refolding under stress conditions (Wang et al. 2004). Heat shock proteins were given that name as their synthesis is induced when cultured cells or the whole organisms are exposed to elevated temperature. This response is observed in every organism in which it has been sought. However, there has been increasingly more data to show that heat shock proteins are not only induced by heat shock, but also by a wide variety of other stresses, and seem to have very general protective functions (Lindquist 1986; Almoguera et al. 1993; Alamillo et al. 1995; Sabehat et al. 1998; Harndahl et al. 1999; Hamilton and Heckathorn 2001; Iba 2002).
