The Newer "Peloria" toadflax flower and the ordinary toadflax flower have identical genetic coding. Yet, the two flowers look very different. How can it be that the same genetic strand gave rise to two very different flowers? What major implications will we see as a result of histone mutations being inherited, thereby acknowledging that epigenetics too are passed from generation to generation? Do you feel more responsible for the integrity of your epigenome and what you will pass onto generations to come? Think about how this discovery alters what we know about evolution.
Jane Rose (5-6A)
While working with two distinct types of the toadflax plant, the “Peloria” toadflax and the ordinary toadflax, botanist Enrico Coen discovered that both plants contained the same genetic material. In other words, they had the same DNA code. DNA is a type of nucleic acid, and it is commonly known as the basis for genetic inheritance. It has an antiparallel, double-helical structure, and it contains a particular sequence of nucleotides (made up of a nitrogenous base, sugar, and phosphate group) that determines an organism’s characteristics (Campbell 88). Coen’s discovery that the two “different” plants contained the same exact genetic material was revolutionary. Conventionally, it was known that things with the same exact genetic code would share the same phenotype, or the same appearance and observable traits (Campbell 267). However, these two plants were entirely different.
ReplyDeleteUpon further analysis, Coen discovered that there was in fact a difference between the two flowers, but the difference was not in their genetic code but their epigenomes. Epigenetics deals with the packaging surrounding the DNA, and the packaging is what instructs the genes when to turn off or on (Shenk 158-159). The reason why the exact same genetic code lead to two different plants is because changes in the epigenomes of each plant, which are influenced by the outside environment, can in turn change the which genes get turned off or on. Thus, environmental factors such as climate, precipitation, and soil quality could have influenced the genetic code of each toadflax plant. This change can occur in two ways: DNA methylation or histone modification. In DNA methylation, methyl groups attach to the DNA backbone at certain places, altering the gene code. In histone modification, the histone proteins which the DNA coil around are altered by chemical tags, changing how tightly the DNA is bound around them (http://www.genome.gov/27532724).
With this knowledge that epigenetics, too, can be inherited, we will see a tweaked theory of evolution, contrary to Darwin’s strict theory of natural selection in which only the “fittest” (those with the best genes) survive. Instead, we will see instead that “lifestyle can alter heredity” (Shenk 161). Lamarck’s theory that what an individual does in his/her life can influence that of his/her offspring actually holds some truth (although the extending neck of the giraffe was a bit off). Now, the lifestyle we employ in our current life has the capacity to influence the epigenetics our offspring inherit, and this brings new gravity to the decisions we make. Whether we chose to eat healthily, exercise, not smoke, etc., can possibly influence the health of our offspring. Personally, with this knowledge of the inherited epigenome I do feel more responsibility; but at the same time I feel renewed hope, because, as it turns out, not even out genes are set in stone.
Diane Kuai (dianekuai@gmail.com)