DNA factories unravelled by new tech

A new technology that enables scientists to watch the tiny machinery inside a living cell has been developed by Dundee scientists. First experiments have revealed miniature factories where copies of the cell's DNA are reproduced.

The technology has been developed by Dr Tomo Tanaka, Professor Julian Blow and their team member Dr Etsushi Kitamura in the College of Life Sciences Division of Gene Regulation and Expression.

Time-lapse microscopy and a specially designed analysis allowed the researchers to watch in detail an area inside the cell's nucleus, just millionths of a metre wide, where DNA is copied.

"No other technology can expose the live cell's workings in such detail and it is likely to reveal some new and exciting discoveries," Dr Tanaka said.

Already it has unravelled the mystery of how DNA is reproduced in the cell - and it is not the way scientists previously thought.

In order for our genes to be passed on to the next generation, our cell needs to make a copy of its DNA; a process known as DNA replication.

Previously it was believed that the DNA strand stayed fixed in the cell while a DNA copying machine moved along it to produce a duplicate strand.

Dr Tanaka and his colleagues have discovered that, rather than the copier being moving along the DNA, the DNA strands are passed through DNA factories - one DNA strand goes in, two come out.

"We can liken the process that we have discovered in cells to an assembly line for making cars, invented by Henry Ford and his engineers. It was a revolutionary idea in industry that products move along a line and engineers stay at fixed places to assemble them. This achieved much more accuracy and efficiency in manufacturing products," Dr Tanaka said.

"Similarly, cells can copy DNA accurately and efficiently by moving it through a stationary copying machine, rather than by moving the copying machinery along stationary DNA."

The discovery has important implications for understanding diseases caused when DNA replication mechanisms are faulty, such as in cancers.

Professor Angus Lamond, head of the Division of Gene Regulation and Expression said, "Cancer is a disease caused by cells dividing and multiplying out of control. This latest advance is a wonderful example of how genetic research in Dundee is leading the way in understanding how cells divide and therefore helps us understand the basic causes of cancer. Future cancer treatments will build upon this improved understanding of what has gone wrong."

The study was published in the journal Cell.