Figure 4.

Molecular rhythms in peripheral tissues do not re-entrain at the same rate in different mouse strains. (A) Representative actograms show slow re-entrainment of wheel-running rhythms in C57BL/6J mice versus rapid re-entrainment in “BALB-like” F2 hybrids (similarly rapid as in BALB/cJ parental strains). Explants were taken 5 days prior, 2 days after, or 9 days after a 6 h phase advance of the LD cycle (red arrows). (B) SCN explants showed near-complete 6 h phase advances of mPer2^Luc bioluminescence rhythms (dashed lines) by day 2 following the phase shift in both C57BL/6J and BALB-like F2 hybrids (left panel), while phase advances were significantly greater in spleen and thymus explants from BALB-like hybrids on day 2 following the phase shift (middle & right panels) (n=3-4/group). (Unpublished data, Weber and Harrington).