Project description:Investigation of whole genome gene expression level changes in Trichodesmium erythraeum IMS101 during a 24-hr light and dark cycle. The diel gene expression analyzed in this study is further described in Muñoz-Marin, M., I. N. Shilova, T. Shi, H. Farnelid & J. P. Zehr. 2019. The transcriptional cycle is suited to daytime N2 fixation in the unicellular cyanobacterium “Candidatus Atelocyanobacterium thalassa” (UCYN-A). mBio 10:e02495-18. https://doi.org/10.1128/mBio.02495-18.
Project description:Investigation of whole genome gene expression level changes in two strains of the cyanobacteria Atelocyanobacterium thalasaa (UCYN-A) from environmental samples. The diel gene expression analyzed in this study is further described in Muñoz-Marin, M., I. N. Shilova, T. Shi, H. Farnelid & J. P. Zehr. 2017. Unicellular cyanobacterial symbiosis facilitates aerobic nitrogen fixation. Science (to be submitted).
Project description:Although N2 fixation can occur in free-living cyanobacteria, the unicellular endosymbiotic cyanobacterium Candidatus Atelocyanobacterium thalassa (UCYN-A) is considered to be a dominant N2-fixing species in marine ecosystems. Four UCYN-A sublineages are known from partial nitrogenase (nifH) gene sequences. However, few studies have investigated their habitat preferences and regulation by their respective hosts in open-ocean versus coastal environments. Here, we compared UCYN-A transcriptomes from oligotrophic open-ocean versus nutrient-rich coastal waters. UCYN-A1 metabolism was more impacted by habitat changes than UCYN-A2. However, across habitats and sublineages genes for nitrogen fixation and energy production were highly transcribed. Curiously these genes, critical to the symbiosis for the exchange of fixed nitrogen for fixed carbon, maintained the same schedule of diel expression across habitats and UCYN-A sublineages, including UCYN-A3 in the open-ocean transcriptomes. Our results undersore the importance of nitrogen fixation in UCYN-A symbioses across habitats, with consequences for community interaction and global biogeochemical cycles.