Hsp70 expression in Enteromorpha intestinalis (Chlorophyta) exposed to environmental stressors

Numerous studies have indicated that stress proteins have potential as biomarkers of exposure to environmental contaminants. Analysis of stress proteins in animals, especially Hsp70, has dominated this research area despite increasing interest in the use of plants as pollution monitors. In the present study Hsp70 expression in Enteromorpha intestinalis has been investigated under exposure to a variety of stressors, to evaluate the potential use of Hsp70 as a biomarker of contaminant exposure in this seaweed. E. intestinalis was exposed to thermal stress, copper under differing conditions of nutrient availability and the triazine herbicide Irgarol 1051. Measurements were also taken to compare Hsp70 with conventional sublethal endpoints of toxicity such as growth and fluorescence induction parameters such as Fv/Fm. E. intestinalis exhibited a typical heat shock response. Hsp70 expression was increased with copper exposure, but proved to be a relatively insensitive biomarker of copper exposure compared to growth measurements. Nutrient limitation enhanced copper toxicity and significantly impaired growth, Fv/Fm and Hsp70 production. Fv/Fm and growth were strongly affected by Irgarol 1051 exposure, but Hsp70 levels were unaltered following exposure to the herbicide. The implications of using Hsp70 expression in E. intestinalis as a biomarker are discussed.