Project description:Nodularia spumigena is a toxic, filamentous cyanobacterium capable to fix atmospheric N2, which is often dominating cyanobacterial bloom events in the Baltic Sea and other brackish water systems worldwide. Phosphate (P) limitation has been considered as one environmental parameter that is somehow promoting the establishment of cyanobacterial mass developments. In the present study, we analyzed the response of the N. spumigena strain CCY9914 towards strong P limitation in an experimental approach. Filaments of N. spumigena were incubated under P-replete and P-deplete conditions for 21 days. Samples for RNA-seq were collected after 7 and 14 days. Growth of the strain was diminished under P-deplete conditions, however, filaments contained more polyphosphate under P-deplete compared to P-replete conditions. High polyphosphate contents were also detected within heterocysts. After 7 days, approximately 100 genes were upregulated in P-deplete filaments, among them was a high proportion of genes encoding proteins related to P-homeostasis such as transport systems for different P species. Many of these genes became also up-regulated after 14 days compared to 7 days in filaments grown under P-replete conditions, which was consistent with the almost complete consumption of dissolved P in these cultures after 14 days. In addition to genes directly related to P starvation, for example genes encoding proteins for bioactive compound synthesis, gas vesicle formation, or sugar catabolism were stimulated under the P-deplete conditions. Collectively, our data permitted to describe an experimentally validated P-stimulon in N. spumigena CCY9914 and provide evidence that severe P limitation could indeed support bloom formation by this filamentous strain.
Project description:Cyanophage infection outcomes depend strongly on host physiological state, yet the transcriptional dynamics of the P-SSP7–Prochlorococcus MED4 interaction under different light regimes remain poorly understood. This dataset captures the time-resolved transcriptional response of Prochlorococcus MED4 following infection with cyanophage P-SSP7 under three light conditions: standard light, high light, and darkness.
Project description:Marine picocyanobacteria are abundant photosynthetic organisms of global importance. They coexist in the ocean with cyanophages, viruses that infect cyanobacteria. Cyanophages carry many auxiliary metabolic genes acquired from their hosts that are thought to redirect host metabolism for the phage’s benefit. One such gene is nblA which is present in multiple cyanophage families. Under nutrient deprivation the cyanobacterial NblA is responsible for inducing proteolytic degradation of the phycobilisome, the large cyanobacterial photosynthetic light harvesting complex. Here we characterized cleavages induced in the cyanobacteria Synechococcus sp. strain WH8109 upon overexpression of the S-TIP37 cyanophage NblA gene compared to cells without NblA overexpression
