By: Sofia Rodriguez
What makes a queen bee, a queen bee and makes a worker bee, a worker bee? It turns out they are genetically similar at birth, but their epigenomes evolve based on their diets.
Within a beehive, there are several discrete and distinct castes, with the highest being the queen bee and the worker bee being below it. These two types of bees have drastically different roles in the hive and look drastically different; but strangely, they are genetically similar. The queen bee is larger and lives longer than worker bees. Queen bees are the only fertile female bees in the entire hive. So with the help of drones, (another type of bee whose sole purpose is to procreate with the queen,) they create viable offspring that are all genetically similar because they all share genetically-similar sperm from the male bees.But with this system, where all bee larvae are born genetically similar, how does one rise above the rest? This is due to epigenetics.
The Difference in Appearances of Types of Bees
Source: Janta Kouj
Epigenetics is the study of how environments impact gene expression. Epigenetics impacts the turning on and off of certain genes, acting as a switch for different genomic sequences. In bees, these switches are histone proteins. The genome is the instructions while the epigenome is how they are read. Therefore, the only difference between the worker bees and the queen bees is the turning on and off of certain genes through nutrition. The epigenome is created through a process called methylation: the covalent bonding of small methyl groups onto the cytosine that allows for genes to be turned on and off. #smallbutmighty These genes encode for different proteins that make up the physical form of the bees. By eliminating or turning off different sequences, the physical makeup of different features is being altered. #dietbod But how does the epigenome of bees altered by histone switch to differentiate them?
Food Comparison and Expression
It all comes down to the food. After birth, if the worker bees determine that a new queen is needed, they randomly pick one of the larvaes and feed it royal jelly instead of pollen and honey like all worker bees and drones. Royal jelly is known as bee milk. It looks like “white snot” and is made of mostly water with combinations and sugars. It is secreted by the heads of worker bees.
Royal jelly is different than regular jelly, pollen, and honey of the worker bees because it has a different ration of mandibular to hypopharyngeal gland secretion. This means that it has no detectable trace of phenolic acid, which comes the flavonoids in the from the plant products eaten by regular worker bees. #tastetherainbow These flavonoids increase the immune responses of adult worker bees in regular pollen and jelly, which allows for them to have a strong immune response and work for long periods of time while the queen lack this. This also helps worker bees detoxify pesticides faster. Royal jelly also has an enzyme that inhibits the protein DMT 1 methyltransferase, which demethylates an entire subset of genes in the larvae, allowing for it to develop into a queen. This also allows for the development of chemical protection of the queen’s ovaries, sheltering the toxic or metabolic effects of plant chemicals. This then allows for the queen to remain fertile while leaving the worker bees sterile. #therealdisneyprincess This decision is made upon the first feeding so the queen would never be fed pollen as a larva and damage her immune system.
One would think that feeding the larvae royal jelly is what makes it into a queen; but rather, is the nutritional castration of withholding royal jelly from the worker bees that makes her the queen by isolating her. The royal jelly diminishes the toxic effects of pollen and honey on the reproductive system.
In conclusion, the impacts on epigenetics on the expression of genes is extremely great, especially in bees. The expression of certain genes differentiates worker bees from their queen bee by turning on and off certain genes that encode for important traits, such as fertility, size, lifespan, or immune system response. And although they may not be as famous as queen bee, Beyonce, they are even more important to innovation in biological studies. #Beeyonce
Chittka, A., & Chittka, L. (2010, November). Epigenetics of royalty. Retrieved from Plos Biology website: https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1000532
Freel, K. (2017, April 13). You can call her queen bee: The role of epigenetics in honeybee development. In The molecular ecologist. Retrieved May 29, 2019, from https://www.molecularecologist.com/2017/04/you-can-call-her-queen-bee-the-role-of-epigenetics-in-honeybee-development/
Maleszka, R. (2008, August). Epigenetic integration of environmental and genomic signals in honeybees: The critical interplay of nutritional, brain and reproductive networks. Retrieved from Taylor & Francis Online website: https://www.tandfonline.com/doi/abs/10.4161/epi.3.4.6697
New England Biolabs. (2012, March 13). What does epigenetics have to do with honeybees? [Video file]. Retrieved from https://www.youtube.com/watch?v=2uiB8Fg8iRg
Pearson, G. (2015, September 2). Royal jelly isn't what makes a queen bee a queen bee. Wired. Retrieved from https://www.wired.com/2015/09/royal-jelly-isnt-makes-queen-bee-queen-bee/
Queen Mary University of London. (2018, August 22). Epigenetic patterns determine if honeybee larvae become queens or workers. ScienceDaily. Retrieved May 31, 2019 from www.sciencedaily.com/releases/2018/08/180822130958.htm
Shi, Y. Y., Wu, X. B., Huang, Z. Y., Wang, Z. L., Yan, W. Y., & Zeng, Z. J. (2012, August). Epigenetic modification of gene expression in honey bees by heterospecific gland secretions. Retrieved from Plos One website: https://journals.plos.org/plosone/article?id=10.1371/ journal.pone.0043727
Spannhoff,, A., Kim, Y. K., & Raynal,, N. J. -.-M. (2011, February). Histone deacetylase inhibitor activity in royal jelly might facilitate caste switching in bees. Retrieved from US National Library of Medicine, National Institutes of Health website: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3059907/