Many biological experiments are performed on groups of cells, under the assumption that all cells of a particular “type” are identical. However, recent evidence from studies of single cells reveals that this assumption is incorrect. Individual cells within the same population may differ dramatically, and these differences can have important consequences for the health and function of the entire population.
Examining genetic function and regulation at the systems level using TIVA
Multicellular organisms are comprised of various different types of cells that are categorized based on their function and phenotypic expression. These cells, however, may not be identical at the molecular level and can be more heterogeneous in terms of their mRNA composition and proteins. Most of the knowledge about variability in genes has come from studies involving unicellular organisms, but it is unknown whether the processes that control variability in gene expression in these single-celled organisms can translate to the cells of the multicellular organisms. The environment in which cells exist can be diverse and have an effect on the gene expression. It is therefore of great biological importance to explore the RNA profiles of cells while the cell is in its natural environment.
Sequencing RNA where it lives by FISSEQ
A group of scientists at Harvard Medical School described a method of sequencing, using fluorescence, without disturbing neighboring cells (in situ), termed FISSEQ, in a 2003 publication (1). This technique allows for the sequencing of libraries fixed in gel or on a glass slide and produces 8bp of sequence. This method, just like other methods, are limited to a handful of genes per specimen, making it costly and time-intensive to localize all the RNA molecules (transcriptome) within any given cell, let alone an entire specimen. In a 2014 publication, they describe a new and improved version of FISSEQ that is capable of sequencing the RNA transcriptome.
Massively parallel polymerase cloning and genome sequencing of single cells using nanoliter microwells
Genome sequencing of single cells has a variety of applications, including characterizing difficult-to-culture microorganisms and identifying somatic mutations in single cells from mammalian tissues. A major hurdle in this process is the bias in amplifying the genetic material from a single cell, a procedure known as polymerase cloning. Here we describe the microwell displacement amplification system (MIDAS), a massively parallel polymerase cloning method in which single cells are randomly distributed into hundreds to thousands of nanoliter wells and their genetic material is simultaneously amplified for shotgun sequencing.
Image courtesy of Nature Publishing Group
Save the Date! 2014 Annual PI Meeting Information
The 2nd Annual Single Cell Analysis Investigators Meeting is scheduled for April 21-22, 2014, at the Neuroscience Center, 6001 Executive Blvd, Rockville, MD 20852. Please save the date! More details related to the agenda, registration, and lodging is now available at https://nihsinglecellmeeting2014.eventbrite.com.