"It's the ultimate selfish element that evolved at the beginning of eukaryotes," said Dr. Lander, referring to any animal, from yeast on up, whose cells have nucleuses in them.

Background During the last decade several genes have been found to be interrupted by selfish genetic elements translated in frame with their host proteins.

Either the whole A-ATPase catalytic subunits was transferred, or the intein alone spread as a selfish genetic element.

The popular consensus at the moment is that introns arose within the eukaryote lineage as selfish elements.

Insofar as natural selection contains a selfish, competitive element, so too does symbiotic evolution.

Specicide - the deliberate extinction of an entire species - could be engineered by exploiting the biology of selfish genetic elements.

As a result, a selfish genetic element can spread through a population extremely fast - far faster than a regular gene - even if it is harmful to its host.

Or, to engineer extinction, devise an extinction gene - a selfish genetic element that has a strongly detrimental effect.

While advantageous, the frequency of this selfish element is reported as low.

There is also evidence that suggests the restriction enzymes may act alongside modification enzymes as selfish elements, or may be involved in genetic recombination and transposition.