TABLE 1.

Period length of locomotor activity rhythms in DD

Study	Line	Background	Genotypea	No. of mice tested	Period (h), mean ± SEM	Pb
1	12	C57BL/6 F2	+/+	2	23.24 ± 0.38
			−/−	4	22.35 ± 0.32	NS
2	135	C3H/He F2	+/+	1	23.60
			−/−	3	23.32 ± 0.12	NS
3	135	129/sv	+/+	6	23.66 ± 0.10
			−/−	6	23.22 ± 0.13	<0.021
4	135	C3H/He F2	+/+	3	23.77 ± 0.06
			−/−	5	23.54 ± 0.21	NS
5	12	129/sv	+/+	12	23.77 ± 0.09
			−/−	12	23.27 ± 0.18	<0.025

^a+/+, wild type; −/−, mPER3 deficient. 

^bNS, not significant.