1999). The absorbance spectrum of cPPB-aE is identical to that of the new pigment (peak X) of dinoflagellates

and both pigments exhibit no chlorophyll fluorescence. These results indicate that the new dinoflagellate chlorophyll derivative is cPPB-aE. This represents the first report of cPPB-aE also being expressed in photosynthetic organisms. GW-572016 There are two hypotheses for the function of cPPB-aE in dinoflagellates. One is that cPPB-aE is a degradation product of chlorophyll a as detoxified catabolite, discussed by Kashiyama et al. (2012). It is reasonable to speculate that the conversion of a toxic chlorophyll molecule to a safe form of cPPB-aE is beneficial to dinoflagellates. However, most unicellular phototrophs, such as cyanobacteria, the chlorophyte Chlamydomonas Ehrenberg and diatoms, contain no or very low levels of chlorophyll degradation products (data not shown). In these organisms, chlorophyll might be converted to colorless small compounds or the chlorophyll degradation products might be excreted from the cells. Why only dinoflagellates retain the chlorophyll degradation product in large amounts is something that needs to be resolved. The second hypothesis is that cPPB-aE

is involved in the quenching of excess energy in photosystems. The wavelength of maximum absorbance of cPPB-aE is longer than that of chlorophyll a and the life time of cPPB-aE fluorescence is very short compared to that of chlorophyll selleck chemicals llc a (Akimoto, unpublished data). These optical characteristics of cPPB-aE support the second hypothesis that cPPB-aE is involved in quenching excess energy. We discovered cPPB-aE in six dinoflagellates belonging to four different lineages and this raises the interesting question as to the origin(s) of this molecule. There are two possible hypotheses. The first is that cPPB-aE was acquired independently in each of the four lineages. Interestingly, all the dinoflagellates possessing cPPB-aE are benthic. This suggests that the production of this particular pigment derivative might be related to their habitat

environments. However, other benthic dinoflagellates from the same habitat do not have this chlorophyll derivative (data not shown), so no such clear correlation can be MCE公司 seen between the presence or absence of this molecule and habitat at this stage. The second hypothesis is that all photosynthetic dinoflagellates possess the ability to produce cPPB-aE to quench excess light energy, but usually there is no need to produce it because light conditions normally suit these dinoflagellates. To understand the evolutionary or ecological significance of the possession of this pigment derivative, an extensive survey of dinoflagellates from various habitats is needed as well as biochemical, physiological, and photochemical experiments using strains under different culture conditions.