This simple system demonstrates not only that a TF can regulate the variance of RNA and protein levels without influencing their mean (as previously identified with various mechanisms [ 28, 42]), but more interestingly, that normalized variance can increase with the concentration of a TF (figure 3B).
Our finding is consistent with that of the previous study [ 1], which suggests that this gene is usually expressed in the rosette stage (about day 8) and stage 5 is beyond day 8. Consequently, in their RT-PCR experiment (until day 20), the same up- and down-regulated variance in expression patterns as shown in Figure 8(D) can be observed.
Although stochastic factors influence variance in population abundance of less aggressive taxa, demographic constraints due to host resistance strongly regulate their populations near a low abundance equilibrium.
We will henceforth call (mu^) and (nu^) the "characteristic" mean and variance of any neuron regulated by this control system.
This was interpreted as evidence that the variance of expression of cis regulated genes is much lower than that of trans regulated genes.
Expression differences in cis regulated genes were found to have lower variances than those of trans regulated genes in this study, and several eQTL studies have found that cis regulated differences in transcription are larger than trans regulated differences [ 3].
To identify set of differentially regulated genes we performed three independent analyses, equal-variance t-statistic, Significance Analysis of Microarrays (SAM) and algorithm EB (empirical Bayes) Wright & Simon.
In trisomy 21, for instance, inter-individual expression variances affect a number of tightly regulated genes.
Beta actin had a high variance and also a tendency to be regulated in the high dose group and therefore only ubiquitin was used.
Only 12 genes were significantly co-regulated in all the subgroups of childhood leukaemia (P<0.01, analysis of variance) (Supplementary Information, Figure 1), with seven regulated in different directions between the subgroups.
