## You are what you eat

It was Waddington's understanding that the epigenetic landscape is formed by the organism itself, so it is not the external environment of the organism, but rather the environment around the developing cell. However, let us try to think whether the external environment can also influence genes in the sense of turning them on or off. Bees can serve as an excellent example as they are social insects that are very interesting for geneticists for several reasons. One of them is the method of sex determination, since in bees diploid females arise from fertilised eggs (they carry two sets of chromosomes (one from the mother and the other from the father) and haploid males develop parthenogenetically from unfertilised eggs (they have only one set of chromosomes obtained from the mother). Another interesting feature of bees is that it is possible to distinguish two phenotypically different groups of females: workers and queens. Although both groups arise from fertilized eggs and are genetically equivalent (they have the same genes in their genome), there is an obvious difference between them at first glance, which lies not only in size, but also in physiology and social behaviour (Figure 6.5).

The question is what causes a diploid larva to develop into a worker in one case and a queen in another. The answer is clear - diet. The fate of the larva is determined by the food it receives during the early stages of development. If she is fed regular food, she develops into a worker, but if she is fed royal jelly, a milk-like secretion of honey bees, she develops into a queen. The development of a queen requires different genes than the development of a worker, and in this case the royal jelly is able to cause the "reprogramming" of these genes. It was also found that the genes that lead to the development of the queen remain switched off (they are not transcribed) in the worker bees. Different genes can therefore be transcribed in individuals with the same genotype. This was a very interesting finding, and as a result, scientists have decided to clarify the mechanism by which royal jelly causes such a change.