Evolution driven by cross species jumping genes.

Researchers find genes jumping from species to species throughout evolution. Those genes are called transposable elements and have the ability to replicate themselves and move to other locations within the genome or even other species apparently.

A transposable elements is a sequence within a genome. They do not code for anything except some that do code for a protein called transposase. This protein allows the transposon to move to another part of the genome. The other area of transposons, the one that codes for nothing is relatively more susceptible to mutations. Thus eventually areas like this may acquire some function. Thus evolution relies on such DNA sequences. Because organisms cannot acquire new genes by just removing an old gene or extending the genome, they have those unused genes that can be mutated. If those segments acquire some good gene they survive, if not those individuals die. It is the basis of evolution and it has been working very well. Those transposons, while essential for evolution, can cause issues for individuals. If one mutates or transfers to another site diseases like: hemophilia A and B, severe combined immunodeficiency, porphyria, predisposition to cancer, and Duchenne muscular dystrophy may arise.

DNA from foods we consume has been shown in the past to pass through the intestine to the blood. Although fragmented, it does pass through, but all studies have shown that there is no transfer of DNA between things we consume and our cells. There is no transfer even in the microbes that live in our gut. Horizontal gene transfer is a bit more complex than that and would require certain conditions to occur. On the other hand we consume so much food that the chances of some of its DNA entering our cells should be relatively high.

A team of researchers looked 759 species and examined two of the most abundant retrotransposons, LINE-1 (L1) and Bovine-B (BovB). Line-1 elements make up about 17% of the human genome. Most studies up until now have focused on few species. This new study focused on so many that they found evidence of horizontal gene transfer between them. This occurring with both L1 and BovB elements. This shows that through evolution, species have been exchanging transposons and affecting each other. I am interested to see what future studies will show and if indeed many species or families of species have evolved through similar pathways and due to their interaction with similar species. Also this might give clues to other researchers to re-investigate whether dietary DNA can transfer to human cells or intestinal microbes. If so, then GMOs might face a new problem. Or not, we may find that only such elements can move through species and that genes engineered on plants and animals we consume lack that ability.

This may also be just a false positive, due to the large amount of species and data processed there would definitely be a pattern found and in such studies it is hard to tell correlation from causation. More research will definitely be necessary to reach any conclusions and for now all we can do is think of the possibilities, which are many. My first thought is on GMOs, which are think are essential for the future. While most agricultural technologies do show promise and some are even better than GMOs for the environment, genetic engineering is a powerful tool and it would be nice to be able to use it without any safety or ethical concerns. It is complex though. As i said before, i think it will be somewhere in the middle. We will have to make sure that genes engineered on GMOs, stay away from transposable elements.

Another concern is from an article we covered here on Qul Mind recently that discusses gene drives. A gene drive is a set of changes to a species genome. This change can be caused to only a few individuals and within a few generations it can spread to nearly the whole rest of the species. This technology faced a lot of criticism and concerns from experts and for good reason, such changes may help us get rid of invasive species but may spread uncontrollably and lead to the extinction of one species or even the transformation of a species to an invasive one. Imagine adding the possibility for those gene drive to move to other species. Now such techniques like gene drives become even harder to suggest using. Still i am not sure if this study gives enough evidence, i think it may be found in the future that the conclusion it gives is untrue or not accurate enough. As always we will have to wait for future studies but this starts very interesting conversations.

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Horizontal transfer of BovB and L1 retrotransposons in eukaryotes

The Stability and Degradation of Dietary DNA in the Gastrointestinal Tract of Mammals: Implications for Horizontal Gene Transfer and the Biosafety of GMOs


By Zina Deretsky, National Science Foundation (Courtesy: National Science Foundation) – National Science Foundation, Public Domain,

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