Thylakoid membranes isolated from leaves of control plants and those exposed to one photoperiod with high illumination and different temperatures were used for immunoblot analyses, using specific antibodies against the PSI A/B protein, the NDH-H subunit of the thylakoidal NDH complex (anti-NDH-H), PTOX and PGR5. Fig. 5shows that the antibody against the PSI A/B protein recognized recognizedonly one polypeptide of 70 kDa, while the anti-NDH-H, anti-PTOXand anti-PGR5 antibodies recognized others of 50 kDa, 33 kDa and10 kDa, respectively, in each thylakoid membrane sample. No addi-tional polypeptide was recognized by the antibodies assayed (notshown). Immunoblots were analyzed densitometrically (Fig. 5).The levels of PTOX and the NDH-H subunit of the NDH complex were higher in the thylakoids of plants exposed to one photoperiod with 37◦C/37◦C and 10◦C/37◦C under high illumination than in leaves from control plants. However, the levels remained similar to the control levels in leaves from plants exposed to 24◦C/24◦C,10◦C/10◦C and 37◦C/10◦C. In contrast, the PGR5 and the PSI A/B polypeptide levels remained similar to the control levels in leaves from plants exposed to 24◦C/24◦C, 37◦C/37◦C and 10◦C/37◦C, but increased in plants exposed to 10◦C/10◦C and 37◦C/10◦C.