Table 2.

Dose effect of γ-irradiation on the p53-dependent induction of the HO-1 and Waf1/p21 in thymus and spleen of mice after whole body irradiation

Organs	Gy	H0-1		Waf1/p21
		Stimulation*	P	Stimulation*	P
Thymus	0.1	nd	–	1.4 ± 0.15	0.03
	0.2	1.8 ± 0.3	<0.05	2.8 ± 1.3	0.01
	0.5	3.1 ± 1.1	<0.05	5.4 ± 1.7	<0.001
	1	9.7 ± 2.1	<0.005	8.9 ± 3.8	0.001
	2	31.3 ± 6.6	<0.005	20.4 ± 6.6	<0.001
Spleen	0.1	nd	–	2.5 ± 0.04	<0.0001
	0.2	1.2 ± 0.3	ns	3.4 ± 1.1	<0.01
	0.5	1.4 ± 0.4	ns	6.0 ± 1.9	<0.005
	1	2.3 ± 0.8	<0.05	10.7 ± 5.8	<0.02
	2	2.9 ± 0.8	<0.005	16.2 ± 2.9	<0.0001

Three hours following whole body irradiation, mice were sacrificed and total mRNA was extracted from thymus and spleen taken from p53 wild-type (p53+/+) mice exposed to irradiation doses of 0.1, 0.2, 0.5, 1 and 2. Non-irradiated mice were treated in parallel. Transcriptional induction was evaluated by real-time RT-PCR as described in Materials and Methods section and expressed relative to mRNA level measured from non-irradiated mice. One-way ANOVA analysis was used to determine significance between stimulation factors of irradiated versus non-irradiated mice. A stimulation factor of 2 with a P value <0.05 was considered as showing a significant up-regulation of the gene expression. Asterisk: mean of 4 (thymus) or 5 (spleen) mice ± mean deviation; nd = not determined; ns = not significant.