In addition, we analyze the extent to which each method can focus on applying the knowledge that improves the search performance, handle conflicting information that suggests improving solutions with opposing modifications, and balance the exploitation of the available knowledge with the exploration of the tradespace to prevent premature convergence on local optima.
The presence of these two opposing modifications as bivalent marks on promoters is often associated with poised gene transcription.
This simulation, therefore, indicates that spontaneous boundary formation by opposing modifications may eventually lead to one modification dictating the opposite modification.
Intermediate connectivity enables faster switching between opposing modifications states and an increased interaction frequency causes switching between nucleosome array states that are almost completely methylated or acetylated.
This opposing A state would be likely to involve a histone modification associated with active gene expression in S. pombe, the opposing modifications were thought to be acetylation/methylation of the same residue on the histone tail [ 4].
In some cases, such as at H3K27 and H3K9, acetylation or methylation can occur at the same histone residue and it is the balance between these opposing modifications that determines the transcriptional status of that region (Rice and Allis, 2001; Tie et al, 2009; Jung et al, 2010; Pasini et al, 2010b).
Chromatin connectivity destabilizes this synergistic system and introduces bistability, illustrating state switching between opposing modification states of the model gene.
We therefore propose that H3K36me3 is the opposing modification to H3K27me3 in the Polycomb-mediated silencing of FLC.
Overall, these dynamics show that H3K4me2 is also unlikely to act as the opposing modification to H3K27me3 during the switch of expression states in vernalization.
None of the H3K36me3, H3K36me2, H3K4me3, and H3K4me2 modifications analyzed exactly fitted the theoretically predicted pattern for the opposing modification to H3K27me3 at FLC during all phases of the vernalization process.
