Expression of Hsp70 in Spartina alterniflora as a bio-indicator for environmental impact

Wang, Yuheng

The long-term goal of our research is to evaluate the health of the Bronx River, Bronx, NY by gauging the effect of environmental stresses on organisms native to the river. Due to the heavy dumping of industrial waste and nearby urbanization, the Bronx River has experienced a dramatic decline in water quality and estuarine health. Specifically, we explored the role of smooth cord grass, Spartina alterniflora, as an indicator of relative environmental stress. Our approach was to monitor expression of the universal stress responding protein, heat shock protein 70 (Hsp70) in grass collected from the Bronx River estuary as well as a relatively less impacted site in Greenwich Cove, Greenwich, CT. We quantified and compared constitutive and heat-induced expression of Hsp70 protein in S. alterniflora from these two sites. Protein expression was determined by quantitative Western Blot analysis, using the housekeeping enzyme, Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as an internal protein loading control. Our analyses over three years consistently show that Bronx River marsh grass expresses higher constitutive expression of Hsp70 when compared to Greenwich Cove. In addition, under controlled heat stress, the grass from the Bronx River does not elicit the same magnitude of response as compared to Greenwich Cove. Our studies demonstrate the relative utility of S. alterniflora as a bioindicator species for environmental impact. Our findings show that GAPDH expression remains stable across sites and conditions, demonstrating its utility as a valid internal control for further studies of this sort.