Individual colonies of certain well-studied cosmopolitan coral genera, such as Acropora, Montastraea, and Pocillopora, yield many reports of mixed infection, while other genera, such as Porites, do not. We further discuss mixed Symbiodinium infections in the context of evolutionary ecology theory. Selection pressures that affect the prevalence of mixed infection may be exerted by variation in host environment, host ontogeny, symbiont transmission strategy,
host regulation of symbiont populations, availability of free-living symbiont lineages, GDC-0068 datasheet competition between symbiont lineages, and niche partitioning of the internal host environment. “
“Coral reefs are increasingly threatened by disease outbreaks, which affect the coral animal and/or its algal symbionts (Symbiodinium spp.) and Wnt inhibitor can cause mass mortalities. Currently around half of the recognized coral diseases have unknown causative agents. While many of the diseases are thought to be bacterial in origin, there is growing evidence that viruses may play a role. In particular, it appears that viruses may infect the algal symbionts, causing breakdown of the coral-algal mutualism. In this study, we screened a wide range of Symbiodinium cultures in vitro for the presence of latent viral infections. Using flow cytometry
and electron microscopy, we found that many types of Symbiodinium apparently harbor such infections, and that the type of putative virus varied within and among host types. Furthermore, the putative viral infections could be induced via abiotic stress and cause host cell lysis and population decline. If similar processes
occur in Symbiodinium cells in hospite, they may provide an explanation for some of the diseases affecting corals and other organisms forming symbioses with these algae. “
“Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler is the most abundant marine unicellular coccolithophore in the ocean and belongs to the group of organisms that have chl c and fucoxanthins as pigments in the photosynthetic light-harvesting complexes (LHCs). In this study, Proteasome inhibitor we report on the isolation and characterization of the mRNAs encoding six light-harvesting complex fucoxanthin-binding proteins (LHCFs) from E. huxleyi. Phylogenetic analysis of these sequences has revealed that they form three distinct subgroups: haptophyte, diatom/haptophyte, and LI818-like. Expression analysis of the six Lhcf genes showed a clear down-regulation at the transcriptional level when the cultures were grown in high light (300 μmol · m−2 · s−1) when compared to equivalent samples in low light (30 μmol · m−2 · s−1). In contrast, little impact on transcript levels was observed between cultures grown in either low CO2 (180 ppm) or high CO2 (750 ppm) at either light intensities. Using polyclonal antibodies to three of the LHCFs revealed a down-regulation in protein levels in response to increased light availability with a minor increase in two of the LHCFs in elevated CO2.