Honey bees as helpers of cancer research

Cancer Research: Honeybees advance science

Scientists at the German Cancer Research Center, in collaboration with Australian colleagues, have used honeybees to investigate why animals with identical genes can develop fundamentally differently - some become queens and the other workers.

„extreme example“ of different development
The researchers decided to investigate the honey bees, as these are according to Frank Lyko of the German Cancer Research Center (DKFZ) „an extreme example of different development fates“ are. Thousands become workers and only one becomes a queen, which in principle brings different life tasks for the animals. While the relatively small workers collect food as infertile animals, keep the hive in order, and care for and feed the brood, the much larger, long-lived queen is busy her entire life producing offspring. Why bee larvae develop so differently with the same genetic predisposition, the researchers have now taken a closer look and their findings in the latest issue of the journal „PLoS Biology“ released.

The epigenetic effect
Researchers have found that different molecular groups attach themselves to the DNA of the bee larvae depending on the diet. The underlying epigenetic effect has been studied scientifically for some time. Epigenetics offers an explanatory model for the influence of external factors on our genes. Thus, depending on the environmental influences on certain DNA building blocks, methylation takes place, in which groups of molecules form 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, because of the epigenetic effect, two very different creatures emerge from exactly the same genes at the end.

Royal jelly or pollen; Queen or worker
In the case of bees, the different diets are crucial for the epigenetic effect. Depending on whether the larvae were fed with pollen or the high-fat and protein-rich royal jelly, the methylation of the DNA components changed, resulting in workers (pollen feed) or queens (royal jelly feed). Depending on the different methylation of certain gene regions, individual characteristics were pronounced to different degrees, the scientists from the DKFZ explained in their current publication. The researchers also created a methylom, a map of the genome that shows exactly where the methyl groups were formed in DNA and where they differed between workers and queens. They found a total of more than 550 genes that differed from each other methylation patterns, most of which were DNA building blocks that play a role in important cell functions or influence the behavior of insects. „This marker is a kind of fine-tuning gene“, explained Ryszard Maleszka from the Australian National University in Canberra.

Without methylation only queens are created
To further substantiate the epigenetic effect of methylating certain DNA building blocks, Australian researchers have mimicked the effects of the royal pine diet by shutting down the enzyme in the bee larvae, which is responsible for the formation of methyl groups on the DNA. The result: Even without royal jelly developed exclusively queens developed from all larvae. This clearly proves the direct relationship 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 supplemented that „these results are far-reaching, because the enzymes that modify the genetic make-up of bees are the same ones 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 because cancer cells are also an example of the epigenetic effect. For healthy cells and cancer cells in an organism originally have the same genome and yet develop completely differently, into normal tissue or tumors. „It is also conceivable that environmental influences and nutrition have an influence (...) and that these effects are mediated by differences in DNA methylation“, said the head of the department of epigenetics at the DKFZ Heidelberg, Frank Lyko. According to this, a methyloma (map of the methyl markers on the DNA) could also reveal in humans whether certain types of cancer will occur and thus make the diagnosis considerably easier. However, it will probably take a while until a method that is suitable for everyday use and not too complicated to develop a human methylome is developed, because the human genome is about ten times larger than that of the bee.

Epigenetics is gaining importance
Epigenetics has not long been at the center of scientific interest in the study of a wide range of diseases, yet numerous studies have already demonstrated the effects of the epigenetic effect on the development of certain diseases. Most recently, an Australian study made speeches, and found that Diet of fathers has a direct impact on the diabetes risk of daughters. To date, the experts had assumed that only the diet of the mother has direct consequences on the health of children. However, the epigenetic effect has apparently led to sperm damage in spermatogenesis and thus brought with it an increased disease risk of the daughters. Since the epigenome changes relatively short-term 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 in the future. (fp, 04.11.2010)

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Picture: Uschi Dreiucker