Project description:Here, we report the comparison of transcriptomes of Anabaena sp. PCC7120 and the FurB(Zur) deletion derivative strain (MN38). Anabaena sp PCC7120 is a cyanobacterium that differentiates specialized nitrogen-fixing cells called heterocysts and that is capable of forming biofilms. Our data showed that the deletion of FurB negativily affected the heterocyst development and the biofilm formation. In addition, the RNA-seq data together with gel retardation assays unveiled that FurB is directly involved in the regulation of several genes related to heterocyst development and biofilm formation and other novel functions different from the ones related to the canonical Zur regulon.
Project description:The genomic sequence of the heterocyst-forming cyanobacterial symbiont Calothrix rhizosoleniae SC01, commonly found associated with the diatom Chaetoceros spp. in the open ocean. The assembly was the result of isolation and culture of Calothrix, followed by sequencing and filtering to remove sequences from contaminating organisms.
Project description:Cell-cell communication is an essential attribute of multicellular organisms. We studied the effects of perturbed communication in multicellular filaments of mutant derivatives of the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120, in which septal proteins were deleted. Filaments of sepJ and sepJ/fraC/fraD deleted strains showed marked differences in growth, pigment absorption spectra and spatial patterns of expression of the hetR gene encoding a master regulator of heterocyst differentiation. To understand the global changes in gene expression that take place as a result of impaired cell-cell molecular transfer, we mapped the transcriptional landscape of wild-type and mutant filaments using RNA-seq, both under nitrogen-replete and nitrogen-poor conditions. Our results show that the effects of sepJ and fraC/fraD deletions are not additive, and that far from affecting only passive transport between cells, perturbations to cell-cell communication in this model organism lead to significant changes in gene expression. Most significant effects include increased expression of genes encoding carbon uptake systems and some components of the photosynthetic apparatus, and decreased expression of genes encoding cell wall components related to heterocyst differentiation and to polysaccharide export. Thus, impairment of intercellular communication strongly affects specific aspects, notably related to carbon metabolism, of the biology of Anabaena.
Project description:Diatoms, which are responsible for up to 40% of the 45 to 50 billion metric tons of organic carbon production each year in the sea, are particularly sensitive to Fe stress. Here we describe the transcriptional response of the pennate diatom Phaeodactylum tricornutum to Fe limitation using a partial genome microarray based on EST and genome sequence data. Processes carried out by components rich in Fe, such as photosynthesis, mitochondrial electron transport and nitrate assimilation are down-regulated to cope with the reduced cellular iron quota. This retrenchment is compensated by nitrogen (N) and carbon (C) reallocation from protein and storage carbohydrate degradation, adaptations to chlorophyll biosynthesis and pigment metabolism, removal of excess electron s by mitochondrial alternative oxidase (AOX), augmented Fe-independent oxidative stress responses, and sensitized iron capture mechanisms. Keywords: Marine phytoplankton, pinnate diatom
