The Frankenstein story suggests that a body patched together body from corpse parts could be given life by a stroke of lightning. In a more scientific context, biochemists believe that Lightning may have contributed to the formation of the early organic molecules that eventually evolved to form all life on earth. Now, in the summer of 2001, a scientist from the University of Lyon has found evidence that lightning can cause microorganisms to accept "foreign" DNA, bringing about frequent and large-scale genetic changes.
Biologists often use electrical fields to make cellular membranes permeable to DNA or other molecules. Pascal Simonet and his team used simulated lightning to cause some Escherichia coli bacteria to absorb plasmids for antibiotic resistance from their environment. These bacteria don't do this in the absence of electrical fields.
Scientists had been wondering about the rapid rate of diversification in microbes caused by gene swapping, or horizontal gene transfer. The effect of lightning now offers a plausible explanation. Simonet believes that about 10,000 bacteria could be transformed by each stroke of lightning.
Until now, the main believed causes of genetic change, usually in the sense of mutation, were
- ultraviolet light,
- harder forms of radiation, such as X-rays and Gamma rays,
- aggressive chemical substances.
Now that lightning, which has been striking our planet since before life began, joins the list of genetic movers and shakers, it becomes interesting to speculate on the effects of man-made electrical fields, such as those found under power line
s and in front of computer monitor
s. Not to worry, higher life forms such as ourselves aren't likely to scrounge genetic material from the environment, even in electric fields. But there is the matter of changed cellular permeability, whose effects are still being studied.
- Demaneche, S. et al.
Laboratory-scale evidence for lightning-mediated gene transfer in soil.
Applied and Environmental Microbiology, 67, 3440 - 3444, (2001).