RESUMO
Exposure of Culex quinquefasciatus larvae to hypothermia or hyperthermia in relation to ecological temperature has resulted in alteration of enzyme activities related to maintenance of free amino acid pool and protein degradation. Sudden changes in water temperature have led to elevation of protein content particularly in molecular weight between 66 and 97.4 kDa. MALDI TOF analysis revealed the presence of putative uncharacterized protein and Phospholipase A2 activating protein in larvae subjected to 40°C for 1 hour which was not found in control and other temperature treated larvae. These proteins may be playing a role in survival of larvae at higher temperatures. Thermal shock has resulted in channeling of free amino acids for protein synthesis and elevation of amino acid catabolism through increased deamination and altered transamination, which resulted in a sharp decrease in free amino acid pool. Inhibition of Leucine amino peptidase and elevation of Cathepsin D, under the influence of thermal shock may be an adaptive response of larvae to prevent unnecessary degradation of protein and at the same time facilitated rapid internal re-organization which may accelerate pupation. Elevated activity of Phenol oxidase and its co-stimulator Trypsin -like Serine protease, along with increased expression of Phospholipase A2 activating protein is a well co-ordinated defense mechanism leading to increased immune response in stressed state. This study assumes significance because variation in environmental conditions such as global warming and their impact on mosquito physiology can influence efficiency of disease vector.
