lagunensis contributes to the ability of this organism to sustain prolonged bloom (continuously

for ∼8 years) under reduced light conditions, but not A. anophagefferens (a few months), remains an open question. “
“The life cycle of the unicellular green alga selleck chemical Haematococcus pluvialis consists of motile and nonmotile stages under typical growing conditions. In this study, we observed that motile cells were more susceptible than nonmotile cells to high light, resulting in a decrease in population density and photo-bleaching. Using two Haematococcus strains, CCAP 34/12 (a motile cell dominated strain) and SAG 34/1b (a nonmotile cell dominated strain), as model systems we investigated the cause of cell death and the protective mechanisms of the cells that survived high light. The death of motile cells under high light was attributed SRT1720 concentration to the generation of excess reactive oxygen species (ROS), which caused severe damage to the photosynthetic components and the membrane system. Motile cells were able to dissipate excess light energy by nonphotochemical quenching and to relax ROS production by a partially up-regulated scavenging enzyme system. However, these strategies were not sufficient to protect the motile cells from high light stress.

In contrast, nonmotile cells were able to cope with and survive under high light by (i) relaxing the over-reduced photosynthetic electron transport chain (PETC), thereby effectively utilizing PETC-generated NADPH to produce storage starch, neutral lipid, and astaxanthin, and thus preventing formation of excess ROS; (ii) down-regulating the linear electron transport by decreasing the level of cytochrome f; and (iii) consuming excess electrons produced by PSII via a significantly enhanced plastid terminal oxidase pathway. “
“Many scleractinian corals must acquire their endosymbiotic dinoflagellates (genus Symbiodinium) anew each generation from environmental pools, and exchange between endosymbiotic and environmental pools of Symbiodinium (reef waters and sediments) has been proposed as a mechanism for optimizing coral physiology in the face of environmental change. Our understanding of the

diversity of Symbiodinium spp. in environmental pools is poor by comparison Amobarbital to that engaged in endosymbiosis, which reflects the challenges of visualizing the genus against the backdrop of the complex and diverse micro-eukaryotic communities found free-living in the environment. Here, the molecular diversity of Symbiodinium living in the waters and sediments of a reef near Coconut Island, O‘ahu, Hawai‘i, sampled at four hourly intervals over a period of 5 d was characterized using a Symbiodinium-specific hypervariable region of the chloroplast 23S. A comparison of Symbiodinium spp. diversity recovered from environmental samples with the endosymbiotic diversity in coral species that dominate the adjacent reef revealed limited overlap between these communities.