Chapter 21

Single Cell Analysis and Multiomics

The assumption of average types is one of the major simplifying assumptions needed

to produce a mechanistic description of a natural system. ¹ Besides, the limited sen-

sitivity of many experimental methods made it necessary to gather materials from

large numbers of cells in order to have a sufficient number of molecules for reli-

able characterization. Continual increases in sensitivity have now made it feasible

to analyse the genome, transcriptome, proteome, metabolome, and so forth from a

single cell, enabling individual heterogeneity even within a single tissue containing

only cells of the same type to be demonstrated.

One contribution to this heterogeneity, especially apparent in rapidly self-renewing

tissues such as the intestinal epithelium, blood, and skin, is the fact that development

of the final type from an undifferentiated stem cell is a continuum, and many interme-

diate types are likely to be found in such tissues. Understanding these development

trajectories is difficult or impossible if the attributes of cells of many different stages

are averaged out in the examination.

Even in a perfectly synchronized tissue, however, there is likely to be heterogeneity

because of the amplification up to macroscopic expression of microscopic, random

variations; they are countered by “peer pressure” (compeer coercion) tending to

produce uniformity.

Especially when working with the minute quantities of material available from a

single cell (e.g., total RNA may amount to some tens of picograms) close to or at

the limits of detection of the employed techniques, ² it was natural to simultaneously

characterize many features to provide corroboration. Hence multiomics was born,

in which the genome, transcriptome, proteome, metabolome, etc., are characterized

and compared, an approach that may ultimately become routine for all biological

investigations.

1 Allen (2007).

2 See, e.g., Adil et al. (2021).

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https://doi.org/10.1007/978-3-030-45607-8_21

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