Heat Shock Protein 60 (HSP60) Response of <Emphasis Type="Italic">Plationus patulus</Emphasis> (Rotifera: Monogononta) to Combined Exposures of Arsenic and Heavy Metals

Organisms produce stress proteins as a response to natural and anthropogenic environmental changes. Induction of stress proteins has been reported in a variety of aquatic organisms, including rotifers, exposed to pollutants. Past studies on stress protein responses of rotifers have focused on exposure to single toxicants. In this study the rotifer Plationus patulus was exposed singly and in combination to various concentrations of As, Cr, Cu, Ni, Pb, and Zn. Following exposure, total protein was quantified (Bradford method) and stress protein 60 (HSP60) was identified using Western blotting. P. patulus induced HSP60 as a response to single exposures to Cr, Cu, Ni, Pb and Zn. HSP60 expression was increased (2 fold) in rotifers exposed to these single elements at both low and high concentrations as compared to unexposed rotifers. Arsenic exposure resulted in a 2 fold decrease in HSP induction. In rotifers exposed to metal mixtures, HSP60 was induced by the presence of As–Zn, As–Cr–Cu–Pb, As–Cr–Cu, As–Cr–Cu–Ni and As–Cr–Cu–Ni–Pb combinations in the media. HSP60 response to As and heavy metals toxicity depends on the type and number of elements present in the media as well as their concentrations and length of the exposure time.