Despite this silencing, a small portion of genes escape inactivation and remain expressed from the inactive X (Xi).
A large portion of genes in the M12 module were expressed in response to wounding (GO: 0009611), biotic stimulus (GO: 0009607), organic acid metabolism (GO: 0006082), and cellular amino acid metabolism (GO: 0006520).
When these lists were compared, we found 8,405 genes shared by all four organisms constituting a large portion of genes identified in each organism.
These findings clearly illustrate the inestimable potential still hidden within the human genome in that a considerable portion of genes are shrouded in darkness, awaiting attention and functional elucidation.
Moreover, a recent microarray analysis of RNAi induced Tip60 knockdown in Drosophila embryonic S2 cell culture also revealed a significant portion of genes that were upregulated in response to loss of dTip60 activity [54].
The AS rate progressively increased during evolution: in yeast only a small portion of genes is alternatively spliced, while in the human genome, the majority of protein-coding genes are known to undergo alternative splicing [85], [86], [87].
This showed that ageing of animals from 14 weeks (at the beginning of the experiment) to 30 weeks (at its end) affected expression of a portion of genes, also in the control condition.
Therefore, DNA methylation is dynamically regulated in the human cerebral cortex throughout the lifespan, involves differentiated neurons, and affects a substantial portion of genes predominantly by an age-related increase.
The six DNA sequences from the L. bostrychophila rickettsial isolate cultivated in ISE6 cells confirmed R. felis identity via the sequencing of a portion of genes from R. felis genome including gltA, Rickettsia specific 17-kDa antigen, and ompA; and, the R. felis plasmid including a pRF diagnostic region and pRF putative tldD/pmbA.
About 60% of the probes had >1-bp overlap with the structural portion of genes.
The GCC correction is applied to a very small portion of genes.
