neoxanthin and diatoxanthin

Carotenoids are essential components of photosynthetic organisms including land plants, algae, cyanobacteria, and photosynthetic bacteria. Although the light-mediated regulation of carotenoid biosynthesis, including the light/dark cycle as well as the dependence of carotenoid biosynthesis-related gene translation on light wavelength, has been investigated in land plants, these aspects have not been studied in microalgae. Here, we investigated carotenoid biosynthesis in Euglena gracilis and found that zeaxanthin accumulates in the dark. The major carotenoid species in E. gracilis, namely β-carotene, neoxanthin, diadinoxanthin and diatoxanthin, accumulated corresponding to the duration of light irradiation under the light/dark cycle, although the translation of carotenoid biosynthesis genes hardly changed. Irradiation with either blue or red-light (3 μmol photons m

Topics: Acclimatization; beta Carotene; Chlorophyll; Euglena gracilis; Gene Expression Regulation; Light; Photosystem II Protein Complex; Xanthophylls; Zeaxanthins

The ecological importance and diversity of pico/nanoplanktonic algae remains poorly studied in marine waters, in part because many are tiny and without distinctive morphological features. Amongst green algae, Mamiellophyceae such as Micromonas or Bathycoccus are dominant in coastal waters while prasinophytes clade VII, yet not formerly described, appear to be major players in open oceanic waters. The pigment composition of 14 strains representative of different subclades of clade VII was analyzed using a method that improves the separation of loroxanthin and neoxanthin. All the prasinophytes clade VII analyzed here showed a pigment composition similar to that previously reported for RCC287 corresponding to pigment group prasino-2A. However, we detected in addition astaxanthin for which it is the first report in prasinophytes. Among the strains analyzed, the pigment signature is qualitatively similar within subclades A and B. By contrast, RCC3402 from subclade C (Picocystis) lacks loroxanthin, astaxanthin, and antheraxanthin but contains alloxanthin, diatoxanthin, and monadoxanthin that are usually found in diatoms or cryptophytes. For subclades A and B, loroxanthin was lowest at highest light irradiance suggesting a light-harvesting role of this pigment in clade VII as in Tetraselmis.

Topics: Carotenoids; Chlorophyll; Chlorophyll A; Chlorophyta; Light; Lutein; Oceans and Seas; Photosynthesis; Pigments, Biological; Xanthophylls; Zeaxanthins