The single cell sequencing technology has emerged as a powerful method to investigate the diversity of genome structure and function of cells. In a recent publication, Liang et al (2014) reviewed the science and techniques of this method to emphasize its future scope in genomic research.
The importance of single cell sequencing stems from the fact that the individual cells in a given tissue do not necessarily have the identical genomes. The individual cells also differ in their transcriptome as well as epigenetic modifications. In addition, cells differ in their origins of development, size and morphology and function. These factors make single cell sequencing a useful approach in underpinning the diversities of genome and transcriptome of individual cells.
Single cell sequencing is performed in three major steps: isolation of cell, whole genome/ transcriptome amplification and sequencing. Individual cells can be isolated by using fluorescence-activated cell sorting or Laser-capture microdissection or by simple micromanipulation (such as pipetting or performing serial dilution). Because of higher throughput, less reagent cost and better accuracy, fabricated microfluidic chips are used as a popular choice for separating single cells in recent times.
After isolation of single cells, the next step is to amplify the whole genome or transcriptome of the isolated cells so that nanogram quantities of DNA or RNA can be generated for sequencing. Liang et al. has provided a comprehensive description of the molecular techniques that are used for amplification of whole genome and transcriptome of single cells. Also, the review meticulously guides the reader on understanding the differences in the approaches for applying the technology in studying single cell genome, transcriptome and epigenome.
The application of single cell sequencing is presently being focused on mammalian and model organisms.
Given the current pace of progress in genomics and transcriptomics studies of insects, it is very likely that the single cell technology will have many applications in insect biology. It can have potential applications in insect developmental biology, for example, in mapping cell fates by integrating single cell sequencing data. Also, it may be useful in performing epigenetic analysis in many insects to better understand its functional role. Additionally, single cell sequencing has potential application in unraveling the transcriptional heterogeneity of specific tissues, for example, midgut or salivary gland cells of vector mosquitoes to infection of disease causing pathogens.
The so-called ‘third generation sequencing’ methods, also mentioned in this review, are a way to think forward in these directions.
To conclude, I borrow the following line from Shapiro et al. Nature Reviews Genetics 14, 618–630 (2013):
“Single-cell analysis is not just one more step towards more-sensitive measurements, but is a decisive jump to a more-fundamental understanding of biology”.