-
![]()
-
![]()
テーマ
専門性☆☆☆
英文レベル★★★
30 DNAはウイルスから?
文
11 What with the threat of bird flu, the reality of HIV, and the genera
unseemliness of having one's cells pressed into labour on behalf of
something alien and microscopic, it is small wonder that people don't
much like viruses. But we may actually have something to thank the little
5 parasites for. They may have been the first creatures to find a use for
DNA, a discovery that set life on the road to its current rich complexity
12 The origin of the double helix is a more complicated issue than it
might at first seem. DNA's ubiquity -all cells use it to store their
genomes - suggests it has been around since the earliest days of life
10 but when exactly did the double spiral of bases first appear? Some
think it was after cells and proteins had been around for a while. Others
say DNA showed up before cell membranes had even been invented/
The fact that different sorts of cell make and copy the molecule in very
different ways has led others to suggest that the charms of the double
15 helix might have been discovered more than once. And all these ideas
have drawbacks. "To my knowledge, up to now there has been no ⚫
convincing story of how DNA originated," says evolutionary biologist
Patrick Forterre of the University of Paris-Sud, Orsay.
13 Forterre claims to have a solution. Viruses, he thinks, invented
» DNA as a way the defences of the cells they infected. Little
more than packets of genetic material, viruses are notoriously adept
at* avoiding detection, as influenza's annual self-reinvention attests.
Forterre argues that viruses were up to similar tricks when life was
young, and that DNA was one of their innovations. To some researchers
25 the idea is an appealing way to fill in a chunk of the DNA puzzle.
270
•
