The potent cytoprotective and folding properties of HSPs are co-opted during oncogenesis, as the HSPs become expressed at high levels to enable tumor cell growth and survival.
These 'splice variants', while encoded within the normal genome, become expressed according to the overall status of the tissue in which they originate (e.g. embryonic, adult-proliferative or malignant).
If the water would suddenly become clear again, this variation would suddenly become expressed, possibly leading to new speciation events as described above.
One possible explanation is that the Kcnq1 promoter is exceptionally strong and that as tissue-specific factors become expressed and bind to it, the silencing effect of Kcnq1ot1 is overcome.
At a later stage, the immunoproteasome is expected to become expressed, which has a different specificity [46].
Frizzleds 4, 6 and 10 showed less obvious changes, with a tendency to become expressed in the adenomas, the increased incidence of FZD6 just reaching significance (P<0.04).
Indeed, some normally silent repetitive elements, imprinted genes and individual X-linked genes have been shown to become expressed in placenta (38– 41).
This might be because the hypoxia time was only 6 h, maybe not enough time for the receptor to become expressed after translation.
This finding may explain why DNA methylation correlated only weakly to gene silencing at the global level since most (2475 out of 4211) of the DNAMe genes were co-modified by the active mark H3K4me3 and therefore were more likely to become expressed.
The mechanisms involved here are difficult to explain but one possibility may be that paralogous gene copies, normally repressed, become expressed thereby providing expressed products to match that of X. laevis.
