All statistical analyses were performed using SAS for Windows 9.3 (SAS Institute, Cary, NC). Gradient bar and heat-shock data were analyzed using nonlinear regression techniques. Based on general linear model (GLM) analyses, the percent viability for the two trials for tetrozolium staining did not differ significantly and the trials were pooled for each treatment. A Tukey’s HSD mean separation(˛ = 0.05) was used to determine treatment differences.