Epigenetic effects
<h2 >Epigenetic effects</h2>
<p >The honey bee queens and workers represent one of the most striking examples of environmentally controlled <a href="http://en.wikipedia.org/wiki/Phenotype" title="Phenotype" >phenotypic</a> <a href="http://en.wikipedia.org/wiki/Polymorphism_(biology)" title="Polymorphism (biology)" >polymorphism</a>. In spite of their identical clonal nature at the DNA level, they are strongly differentiated across a wide range of characteristics including anatomical and physiological differences, longevity of the queen, and reproductive capacity.<sup id="cite_ref-5" class="reference" ><a href="http://en.wikipedia.org/wiki/Royal_jelly#cite_note-5" >[6]</a></sup> </p>
<p>
Queens constitute the sexual caste and have large active ovaries, whereas workers have only rudimental inactive ovaries and are functionally sterile. The queen/worker developmental divide is controlled <a href="http://en.wikipedia.org/wiki/Epigenetics" title="Epigenetics" >epigenetically</a> by differential feeding with royal jelly; this appears to be due specifically to the protein <a href="http://en.wikipedia.org/wiki/Royal_jelly#Royalactin" >royalactin</a>. </p>
<p>
A female larva destined to become a queen is fed large quantities of royal jelly; this triggers a cascade of molecular events resulting in development into a queen.<sup id="cite_ref-Maleszka.2C_R_2008_2-1" class="reference" ><a href="http://en.wikipedia.org/wiki/Royal_jelly#cite_note-Maleszka.2C_R_2008-2" >[3]</a></sup> It has been shown that this phenomenon is mediated by an epigenetic modification of DNA known as <a href="http://en.wikipedia.org/wiki/Epigenetics#DNA_methylation_and_chromatin_remodeling" title="Epigenetics" >CpG methylation</a>.<sup id="cite_ref-6" class="reference" ><a href="http://en.wikipedia.org/wiki/Royal_jelly#cite_note-6" >[7]</a></sup> </p>
<p>
Silencing the expression of an enzyme that methylates DNA in newly hatched larvae led to a royal jelly-like effect on the larval developmental trajectory; the majority of individuals with reduced DNA methylation levels emerged as queens with fully developed ovaries. This finding suggests that <a href="http://en.wikipedia.org/wiki/DNA_methylation" title="DNA methylation" >DNA methylation</a> in honey bees allows the expression of epigenetic information to be differentially altered by nutritional input.</p>