Project description:Picocyanobacteria from the genus Synechococcus are ubiquitous in ocean waters. Their phylogenetic and genomic diversity suggests ecological niche differentiation, but the selective forces influencing this are not well defined. Marine picocyanobacteria are sensitive to Cu toxicity, so adaptations to this stress could represent a selective force within, and between, “species” also known as clades. We compared Cu stress responses in cultures and natural populations of marine Synechococcus from two co-occurring major mesotrophic clades (I and IV). Using custom microarrays and proteomics to characterize expression responses to Cu in the lab and field, we found evidence for a general stress regulon in marine Synechococcus. However, the two clades also exhibited distinct responses to copper. The Clade I representative induced expression of genomic island genes in cultures and Southern California Bight populations, while the Clade IV representative downregulated Fe-limitation proteins. Copper incubation experiments suggest that Clade IV populations may harbor stress-tolerant subgroups, and thus fitness tradeoffs may govern Cu-tolerant strain distributions. This work demonstrates that Synechococcus has distinct adaptive strategies to deal with Cu toxicity at both the clade and subclade level, implying that metal toxicity and stress response adaptations represent an important selective force for influencing diversity within marine Synechococcus populations.
Project description:We compared changes, induced by the addition of 100 nM and 5 mM glucose in the proteome and metabolome complements in several strains of Synechococcus and Prochlorococcus, growing either under standard light conditions or darkness. Our results demonstrate that glucose is being metabolized by these cyanobacteria, using mainly the oxidative pentoses pathway, while no evidence was found for the involvement of the Entner-Doudoroff pathway in this process. We observed differences in the metabolic strategies for glucose utilization, both between genera, and between Prochlorococcus MED4 and SS120 strains, which might be related to their specific adaptations to the environment. Our results also suggest that marine cyanobacteria can detect nanomolar glucose concentrations in the environment and that glucose might be used to sustain metabolism under darkness.
Project description:We compared changes, induced by the addition of 100 nM and 5 mM glucose in the proteome and metabolome complements in several strains of Synechococcus and Prochlorococcus, growing either under standard light conditions or darkness. Our results demonstrate that glucose is being metabolized by these cyanobacteria, using mainly the oxidative pentoses pathway, while no evidence was found for the involvement of the Entner-Doudoroff pathway in this process. We observed differences in the metabolic strategies for glucose utilization, both between genera, and between Prochlorococcus MED4 and SS120 strains, which might be related to their specific adaptations to the environment. Our results also suggest that marine cyanobacteria can detect nanomolar glucose concentrations in the environment and that glucose might be used to sustain metabolism under darkness.