Jumping genes

The transfer of genetic material is well known to occur in a vertical orientation. Parents pass their genes on to their children, and their children pass those genes on to the next generation. This fact allows scientists to analyse particular genes and to use the pattern of inheritance to build the tree of life.

It is also well known that the bacteria at the base of this tree form more of a fuzzy bush. This is because bacteria are much more promiscuous than their mammalian counter-parts. While invertebrates stick exclusively to members of their own tribe, bacteria are happy to have sex with a completely different species and will even engage in necrophilia if the occasion arises. This swapping of genes between species is called horizontal gene transfer and was thought to be the purview of bacteria (and some fungi) only.

But now scientists have discovered that transposons (jumping genes) can be transmitted from parasite to host - at least in some special cases. The parasite in this case is the blood-sucking triatomine, a parasite which regularly bites humans and can carry Chagas disease. Researchers found the invertebrate had transposon DNA which was also found in some vertebrate hosts, namely the opossum and the squirrel monkey (but not humans - yet). These jumping genes were 98% identical between the different hosts.

Although this is a clearly a rare and special case, it does demonstrate that genetic transfer between different species is possible. This finding increases the risk associated with genetic engineering and emphasises that once a gene is released into the ecosystem total control of the set of instructions cannot be guaranteed. On the other hand, what scientists do when genes are artificially transferred from one species to another is not much different to this newly discovered natural process. Perhaps this finding may help to ease the environmentalists' fear that genetic engineering is bringing Dr Frankenstein's monster to life.


Clément Gilbert, Sarah Schaack, John K. Pace II, Paul J. Brindley, Cédric Feschotte. A role for host-parasite interactions in the horizontal transfer of transposons across phyla. Nature, 2010; 464