Gene, transcript, protein, and meta

Gene, transcript, protein, and metabolite levels can also be observed at the single-cell level. For example, genomic sequencing of single bacteria cells, including extrachromosomal genetic elements, from Saanich Inlet, Canada, revealed which cells were infected and by how many viruses (Roux et al. 2014). In another example, transcriptomes from single Synechocystis sp. PCC 6803 cells in the laboratory revealed increased gene expression heterogeneity following nitrogen starvation stress, especially in mobile elements (e.g., plasmids and transposons) (Wang et al. 2015). Similarly, Taniguchi et al. (2010) observed that the protein levels in individual Escherichia coli cells in the laboratory were heterogeneous and uncorrelated with mRNA, Jang et al. (2016) observed intracellular concentrations of l-tryptophan in individual E. coli cells using a lab-on-a-chip device in the laboratory, and Malmstrom et al. (2004) used a combination of microautoradiography and fluorescence in situ hybridization to quantify dimethylsulfoniopropionate (DMSP) assimilation by individual cells in several marine habitats.