The study of Epigenetics.. dare you to stick your hand in
Plant researchers from McGill University and the University of California, Berkeley, have announced a major breakthrough in a developmental process called epigenetics. They have demonstrated for the first time the reversal of what is called epigenetic silencing in plants.
The findings are important to develop a better understanding of gene regulation in the continuing quest to breed enhanced crops that produce higher yields, are more resistant to disease and can better tolerate environmental stress – all keys to helping improve the world’s food supply. But perhaps even more important, the discovery may lead to new insights into how epigenetic processes work in the human body, which could assist in developing new ways of modifying our genetic makeup to help us avoid such diseases as cancer.
Although nearly every cell in our body is genetically identical, the researchers explained, each cell type expresses a distinct set of genes. Changes to the proteins around which DNA is wound are called “epigenetic” modifications, because they alter patterns of this gene expression without changing the actual DNA sequence. However, like changes in DNA sequence, epigenetic modifications can be passed on from parent cell to daughter cell, ensuring each cell line has the proper characteristics consistently over many generations.
This process must be repeated each generation, and there is good evidence in animals that, during early development, there is a wave of epigenetic reprogramming that effectively “resets” this system. Some genes, it seems, must be more actively reset than others. And genes that do the same thing in every cell, regardless of tissue type, may not have to be reset at all.
One kind of gene is quite distinct from all of the others, because it is nearly always epigenetically inactivated. These are the genes carried by transposons, or “jumping genes.” Transposons are mutagens, genes that can modify their host cell in different ways, and lead to a predisposition to cancer, for example.
The researchers’ experiments with corn – technically known as “maize” – suggest the propensity to maintain epigenetic states can vary depending on the position of the transposons within the genome.
Many organisms, from worms to humans to plants, have learned to tame transposons by epigentically “silencing” them: if they can’t express their genes they can’t jump. If they can’t jump for long enough, their DNA sequence slowly accumulates errors, and they become molecular fossils. Most transposons in most organisms are silenced in this way, but some remain quite active.