DNA is the hereditary material in humans and almost all other organisms. The information in DNA is stored as a code made up of four chemical bases or nucleotides, abbreviated A, G, C and T. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.
Samples of DNA, genes and cells are extracted from any organism, for example patients or plants, then sequenced to typically determine if the DNA contains mutations, which genes are expressed and where the genes are expressed. The information could be used for various purposes such as diagnosing cancer, non-invasive prenatal test, drug prescription and forensic.
Sequencing is the method to determine the order of DNA nucleotides in an individual's genetic code. To determine the sequence of a batch of the same type of cells Next Generation Sequencing has become indispensable, speeding up the process and reducing the cost. NGS makes it possible to sequence a human genome in only days to weeks, but imaging and fluidics are still limiting the capacity.
A new application is to sequence the RNA in individual cells to be able to differentiate and identify cell types with a much higher accuracy and give better insights into how neighboring cells interact. This requires that both the sequences can be detected and the cells can be visualized in 3D.
The recent advances in single-cell genomics analysis of cells and tissues has initiated the Human Cell Atlas project, a global effort comparable to the Human Genome project to create comprehensive reference maps of all human cells.