Cover picture: During periods of high light or other stressful conditions, triplet statesformed readily on the chlorophyll dimer (white)are quenched by their transfer to a carotenoid (orange) in the bacterial photosynthetic reaction center. This photoprotective reaction (ball and cone arrow) involves an intervening monomeric chlorophyll (yellow). The role of the protein in this reaction has been investigated by characterizing the effects of substitutions at key residues, L181Phe (green) and M208Tyr (red), which are proximal to the cofactors involved. Image rendered by Frank Wood, Lawrence Berkeley National Laboratory. See the article by Laible et al. on p. 2623.