Variability in protein content of pollen of Castor bean (Ricinus communis) before and after exposure to the air pollutants SO2 and NO2

The role of air pollution has been suspected to be an important factor in the recent increase in the incidence of respiratory diseases. The ambient air, which is the carrier of pollen grains, also incorporates pollutants from the atmosphere, leading to alteration of the pollen proteins. Several studies have reported higher risk of development of pollinosis in the areas of dense vehicular traffic as compared to the less polluted areas. The objective of the present investigation was to study the effect of chemical air pollutants (SO2 and NO2) on the soluble total protein content of the pollen of Ricinus communis taken as a model system. Pollen grains of R. communis were collected and exposed to different (100, 200, 300, 400 and 500 mug/m(3)) concentrations of SO2 and NO2 individually, as well as together, for 8, 16, 32 and 48 hours. Proteins were extracted from exposed pollen and also unexposed pollen, which acted as control. The variation found in the protein content was analysed statistically. In the exposed pollen, total protein content showed a significant decrease (p<0.05) in the extracts from the unexposed pollen to SO2 and NO2 . It varied from 1.84 to 11.01 mg/ml for the extracts from pollen exposed to SO2 only, whereas NO2 exposure recorded values for total protein from 0.82 to 3.44 mg/ml only. There was a gradual decrease in the soluble protein content with increase in the concentration and duration of exposure in the pollen exposed to SO2 and NO2 together (p<0.05).