The usage of the terms such as 'DNA' and 'genes' has exploded in recent years and is commonly used to denote characteristics and traits in people, features of products and even as lyrics for a song. The theory of genetics that genes assign traits to individuals has been rooted so deeply into our psyche, that we fail to see the other side of the story completely. The role of the environment in shaping how our genes function is a fact that is unheard by many people and is something I would like to shed a little light on in this post.
The public understanding about genetics is more or less like the way people follow astrology . If the newspaper predicts that the day at work will not go well, we tend to blame the stars/ sun sign for everything that goes wrong that day. Similarly, the presumption that genes control the way we function and act, has set the tone for genes to be solely in control of everything that is happening inside our cells. However, this is not how genes work. There is a machinery that allows genes to adapt to their surroundings without actually changing the DNA sequence. These are not mutations that are stopping gene function or restarting them, these are minor changes that can increase or decrease gene expression, introduced as a result of conditions in the organisms environment. Called epigenetics, these changes are inheritable and can be passed on to future generations as well.
In the past, there have been many studies that have shown how epigenetic changes can be brought about in genes. Methylation of DNA, role of non-coding RNA and modification of histone proteins are a few of the epigenetic methods that we have been able to unearth so far. A recent study published in Science by Daniel Simola and colleagues studied histone protein modification in carpenter ants and were able to externally amend behaviour in these ants.
The colony of a carpenter ant consists of a queen, her brood and several thousands of workers. We know that all worker ants are genetically the same but are given different tasks in their colonies. There is no exception in carpenter ants as well, where smaller ants or minors are assigned the task of taking care of the young and forage for food, whereas the larger ants or majors defend the colony. Using drugs that affect acetylation of histone proteins (Histone deacetylases or HDAC, the researchers saw an increase in scouting and foraging activity in minor ants. Thus, lower the acetylation, larger was foraging activity seen in the ants. Conversely, this increased foraging could be dropped by using a inhibitor of histone acetyltransferase (HATi).
|A Carpenter ant (Camponotus ligniperda)|
(Photo credit: Wikipedia)
|Diagram showing behavioral differences in major and minor carpenter ants when treated with HATi and HDACs.|
Image credit: Simola et al., 2016. doi:10.1126/science.aac6633
Using this information, the researchers were able to induce foraging behaviour in major ants (who are built to defend and protect) and retain them for up to 50 days of age. This goes to show that even though these ants are genetically programmed to carry out a certain task, their behaviour can be modified using external factors. Since a large number of these proteins and enzymes are common among insects and even vertebrates, it is safe to assume that such epigenetic change in behaviour can be brought about in vertebrates as well.
The study also found that there is a window of opportunity, where epigenetic changes can result in behaviour modification and there is a lot of work to be done to understand this window, right from why it exists, how it functions to why it closes as the animal matures. Nevertheless, the study manages to show that genes are not in complete control and your environment has say too.
If you liked reading this post, you might also like our other post about cells not being ruled by genes.
Simola DF, Graham RJ, Brady CM, Enzmann BL, Desplan C, Ray A, Zwiebel LJ, Bonasio R, Reinberg D, Liebig J, & Berger SL (2016). Epigenetic (re)programming of caste-specific behavior in the ant Camponotus floridanus. Science (New York, N.Y.), 351 (6268) PMID: 26722000