Table 4.

The effect of toxicity degree on expression variation stratified by the set of environmental stress response (ESR).

Gene group	Ca_Na_exposure		Chemostat		Environmental Stress		Oxidative Stress
	β	p-value	β	p-value	β	p-value	β	p-value
ESR	-0.0710	0.0053	-0.0314	0.0532	-0.0176	0.3640	0.0026	0.8708
Non-ESR	-0.0848	2.09e-13	-0.0354	1.11e-07	-0.0579	1.28e-11	-0.0091	0.2086

The linear model is built for each of the four gene expression datasets, respectively. β is the linear coefficient in the linear model and the p-value is related to the null hypothesis that β ≠ 0 versus β = 0.