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Bee gene research solves royal riddle


Beekeeper preparing a beehive

(Source: iStockphoto)

Last time I talked about the terrible Dutch famine of 1944, a result of the Nazi occupation during World War II.

Here, the pregnant women in the local population gave birth to smaller babies, which is what you would expect, if the pregnant mothers were being starved.

But in the 1960s, their children gave birth to babies smaller than normal, and in the 1980s, these now grown-up babies in turn gave birth to babies that were smaller than average.

Something had happened to the DNA of the pregnant women.

We started looking at genetics at least 6000 years ago. That's the age of a Babylonian tablet that describes the pedigrees of horses, and various inherited characteristics, such as height.

We started using science and maths to understand genetics back in the 1850s, when the Augustinian monk, Gregor Mendel, started his studies by breeding the edible pea. He looked at seven characteristics including the height of the plant, and the colour of the seeds.

Work on genetics continued unabated, and by the 1960s, we had worked out that the DNA molecule looks like a ladder, with two side rails and billions of 'rungs'.

And we had also worked out that any three of these rungs would get the cell to assemble an amino acid.

Put enough amino acids together and you get a protein, and put enough proteins together and you get a living creature.

But there were a few unanswered questions with this neat little theory.

For example, if the DNA is the same in each cell of a growing baby, then how come some cells turn into liver cells, while others turn into kidney cells?

The answer is that the genes are controlled, or regulated.

For example, the kidney is made of kidney cells. These kidney cells have, like all the cells in the body, the potential to make any organ.

But most of that potential is switched off. In the cells of the kidney, only the genes to make more kidney cells are switched on.

It's the same in the liver, and the heart, and so on. Only the genes to make that particular organ are switched on, while all the others are switched off.

This is called gene regulation.

This process of gene regulation is how the same DNA can make very different cells. In other words, the DNA is the same in every cell of your body.

But what happens to the DNA, and how it is 'read' to make proteins, varies from cell to cell.

This process of gene regulation is involved in how identical DNA in fertilised bee larvae can make very different creatures: a worker bee, or a queen.

In a bee hive, the queen bee is constantly generating a few thousand eggs each day. Only the ones that are fed royal jelly will turn into a new queen that is very different from the other bee.

For starters, she's a queen, she is fertile and quite a bit bigger than the other bees.

We didn't understand why until 2008, when Professor Ryszard Maleszka and his colleagues from the Australian National University worked out how royal jelly turns a regular egg into a queen bee.

The royal jelly is squirted around the bee eggs, which turn into bee larvae. But after a certain stage, some are selected for higher duties and from then on, they alone get 100 per cent royal jelly, while the future workers are put on lesser rations.

The chemicals in the royal jelly work their way into the growing creature that will turn into a queen bee.

Professor Maleszka showed that royal jelly added extra methyl groups to the bee's DNA. In turn, these methyl groups changed how the DNA was being read.

A methyl group is a very simple molecule: just one carbon atom, and three hydrogen atoms.

So in the case of the baby bee's DNA, the rungs that made up the DNA ladder of life were still the same, they were unchanged.

But a chemical change had been made to the bee's DNA. The chemical change was that methyl groups were being added to the side rails of the DNA molecule. This is why this new field is called epigenetics, because changes are made near the DNA, which is your basic genetic material.

So now we are beginning to understand how royal jelly can transform a regular bee into a queen bee. And these methyl groups can be inherited.

This is how the reduced size of babies, caused by the Dutch famine of World War II, was passed down generations of Dutch women.

And that's not all. Next time I'll talk about how your lifestyle can affect the growth of a cancer in your body.

Tags: beekeeping, genetics, dna

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Published 27 October 2009

© 2014 Karl S. Kruszelnicki Pty Ltd