Figure 2.

Light-induced down-regulation of CRY2 expression. (A, B) Immunoblots showing CRY2 (A) or CRY1 (B) protein from 4-day-old etiolated Arabidopsis seedlings exposed to red light (R; 24 μmol s⁻¹ m⁻²), green light (G; 21 μmol⋅s⁻¹⋅m⁻²), UV-A light (U; 22 μmol⋅s⁻¹⋅m⁻²), blue light (B; 20 μmol⋅s⁻¹⋅m⁻²), or kept in the dark (D) for the indicated time before harvesting. Similar amounts of protein for each sample were fractionated in 10% SDS/PAGE gels, and blotted to nitrocellulose membranes; the immunoblots were probed with anti-CRY2 (A) or anti-CRY1 (B) antibodies. (C) An immunoblot showing CRY2 protein level in wild-type seedlings grown under continuous red light (20 μmol⋅s⁻¹⋅m⁻²) with (lane B) or without (lane R) blue light (5 μmol⋅s⁻¹⋅m⁻²) treatment for 1 hr before harvesting. (D) A northern blot showing CRY2 mRNA level (CRY2) in wild-type seedlings grown under red light (20 μmol⋅s⁻¹⋅m⁻²) with (lane B) or without (lane R) blue light (20 μmol⋅s⁻¹⋅m⁻²) treatment for 1 hr before harvesting. The same blot was stripped by using boiled 0.05 × standard saline citrate, 0.01 M EDTA, 0.1% SDS for three times and reprobed with the cDNA of 18S rRNA.