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The field of epigenetics is an emerging area. It aims to strengthen …
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Biology Articles » Genetics » Epigenetic Microenvironment Awakes Genes » Introduction
Introduction - Epigenetic Microenvironment Awakes Genes
As much as environmental cues prompt the
behavioural expression of an organism, so much so is the expression of genes
under the influence of epigenetic microenvironment(1). Despite the
fact that all cells of a eukaryotic organism share the same genome, they tend
to express different phenotyes (proteins, viz., myosin, acetylcholine,
haemoglobin, cytokines, hormones, etc.).
That is to say that the environment in which a set of genes of the cellular
genome works may not be uniform. There
is an inbuilt variability in the molecular vicinity among cells. For example, each of the germ layers
(prospective organ forming areas) in a gastrula provides a set of microenvironment
for the cellular genomic machinery to direct their functions(2). Along
with the genes actively expressing, the corresponding sets of epigenetic
factors are also being doubled during mitosis and shared by the progeny of each
of the germ layers, and thus possibly manifest a differentiated state (3). The formation of three germinal layers out of
the blastomeres (212 in frog) of cleavage stage is another
intriguing phenomenon for setting up a microenvironment infused with epigenetic
factors for a pack of cells to differentiate in the direction predestined by
epigenetic factors. Therefore, the
involvement of myriad epigenetic factors in the phenotypic expression indicates
that the biological system is not a simple mould to operate linearly in an
arithmetic fashion but an intricate manifestation working under the influence
of a variety of factors (4). Among
eukaryotes, the simple Mendelian principles of inheritance of a particular
trait seem to be beyond prediction, primarily because of the influence of
epigenetic factors. The late onsets of
diseases (Alzheimers, Parkinson’s and autoimmune diseases, diabetes etc.,) are
the classical examples representing the influence of epigenetic
microenvironment (5 & 6). Typically,
the epigenetic factors regulate the inheritance of a particular phenotype, the
qualitative attribute of which falls in a range (variegation). Throughout the life of an organism, cellular
epigenetic factors enable cells to respond to environmental signals conveyed by
sensory nerve impulses, hormones, growth factors, cytokines, etc.,(7). Thus, the new field of epigenetics needs to
be explored in relation to the functioning of genes.
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