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Cancer research: honeybees advance science
Scientists from the German Cancer Research Center, in collaboration with Australian colleagues, used honey bees to investigate why animals with identical genes can develop fundamentally differently - some become queens, the other workers.
“Extreme example” of the different development The researchers decided to investigate the honeybees because, according to Frank Lyko from the German Cancer Research Center (DKFZ), they are “an extreme example of different developmental fates”. Thousands become workers and only one becomes queen, which basically entails different life tasks for the animals. While the relatively small female workers collect food as sterile animals, keep the beehive in order, and tend and feed the brood, the much larger, long-lived queen is busy producing offspring all her life. The researchers have now taken a closer look at why bee larvae with the same genetic predispositions develop so differently and have published their results in the current issue of the specialist magazine “PLoS Biology”.
The epigenetic effect The researchers have found that, depending on the food, different groups of molecules attach to the DNA of the bee larvae. The underlying epigenetic effect has been scientifically investigated for a long time. Epigenetics offers an explanatory model for the influence of external factors on our genes. Depending on the environmental influences, methylation takes place on certain DNA components, in which groups of molecules are formed around individual DNA segments, which lead to the activation, regulation and deactivation of the respective DNA sequence. The genetic code is not changed by this process. And yet, due to the epigenetic effect, in the end two very different living beings emerge from exactly the same genes.
Royal jelly or pollen; Queen or worker In the case of bees, the different food types are decisive for the epigenetic effect. Depending on whether the larvae were fed pollen or the fat and protein-rich royal jelly, the methylation of the DNA building blocks changed and workers (pollen feed) or queens (royal jelly feed) were created. Depending on the different methylation of certain gene regions, individual features were developed differently, explained the scientists from the DKFZ in their current publication. The researchers also created a methyloma, a map of the genetic make-up that shows exactly where in the DNA the methyl groups were formed and where they differ between workers and queens. They found a total of over 550 genes that had different methylation patterns, most of which were DNA building blocks that play a role in important cell functions or influence the behavior of insects. “This marking is a kind of fine-tuning of the genes,” explained Ryszard Maleszka from the Australian National University in Canberra.
Without methylation, only queens are created DNA is crucial. The result: Even without royal jelly, only queens developed from all larvae. This clearly demonstrates the direct connection between methyl labeling and later development. “With our study, we can show how the environment is directly linked to DNA through nutrition. Environmental influences can temporarily modify the genetic hardware, ”explained Ryszard Maleszka. The expert added that "these results (are) far-reaching, because the enzymes that modify the genetic material in bees are the same as those that mark DNA in the human brain."
Epigenetic effect in cancer cells The fact that the study results are also particularly interesting for cancer research is due to the fact that cancer cells are also an example of the epigenetic effect. Because healthy cells and cancer cells in an organism originally have the same genome and nevertheless develop completely differently, into normal tissue or tumors. "In principle, it is also conceivable that environmental influences and diet have an influence (...) and that these effects are mediated through differences in DNA methylation," said Frank Lyko, the head of the epigenetics department at the DKFZ Heidelberg. According to this, a methyloma (map of the methyl markings on the DNA) could also provide information in humans as to whether certain types of cancer will occur and thus make the diagnosis much easier. However, it will be a while before a method for creating a methylome in humans that is suitable for everyday use and is not too complex is developed, because the human genome is about ten times larger than that of the bee.
Epigenetics is gaining in importance Epigenetics has not long been the focus of scientific interest in the study of a wide variety of diseases, and yet numerous studies have already proven the effects of the epigenetic effect on the development of certain diseases found that fathers 'diet has a direct impact on daughters' diabetes risk. Up until now, experts had assumed that only the mother's diet had a direct impact on the children's health. However, the epigenetic effect has obviously led to damage to the sperm during spermatogenesis and thus increased the risk of illness for the daughters. Since the epigenome changes relatively quickly and much more easily than the genome due to environmental influences, the influence of environmental factors on the genetic disposition of certain diseases should always be kept in mind. (fp, 04.11.2010)
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