To compensate for this and identify cartilage-selective genes expressed at lower levels, the approach presented here placed increased significance on the preferentially expressed genes that showed the least variation of expression in non-cartilage tissues.
These images have been captured in regulated illumination, and the variation of expression is moderated (Figure 6). Figure 6 Samples from FACES94.
Proteins with organ expression bias (higher expression in one organ as compared to the other two organs) exhibited higher variation of expression and the proportion of these proteins in each organ explained at least partly inter-organ differences in protein expression variation.
These data indicated that the variation of expression of ribosomal protein genes caused by replication within one tissue was much smaller than the variation between tissues.
mRNA gene expression data from 25 cell lines (see Table S1) were analyzed for variation of expression levels across the cell lines.
Our other finding of a temporal variation of expression of CB1 in the Fallopian tube reflects that of many genes in the endometrium suggesting a role for progesterone in the human endocannabinoid system [24], [25].
The dentate gyrus in contrast had a completely different expression pattern with low relative expression intensities and without significant variation of expression levels during development, except for a slight drop between P1 and P11 (p<0.001; Figure 3).
Therefore, we speculate that eukaryotic introns may function as carriers for ncRNAs and, through the process of intron gain and loss, may affect the level and variation of expression of ncRNAs.
Moreover, increasing evidence has suggested that CCN proteins are involved in tumorigenesis, and variation of expression of these molecules has been observed in several types of cancers [8], [9].
These genes present significant variation of expression amongst tissues.
This suggests that large inter-individual variation of expression levels can obscure group-specific differences.
