Evolution Were cancer genes originally transmitted from plants to humans?

How does the transfer of genes affect different species??

Cancer affects many people around the world today. Cancer is widespread and causes millions of deaths. Experts were now trying to find out where the cancer genes originally came from in humans. The researchers found that transfer of genes between plants and mammals has radically altered mammalian genes.

Researchers at the University of Adelaide have found in their recent research that so-called cancer genes may have arisen through a transfer of genes between plants and mammals during evolution. These genes could be the source of why cancer forms in humans. The physicians published the results of their study in the English-language journal "Genome Biology".

Certain genes are involved in the development of cancer. Were these genes originally transferred from plants to mammals? (Image: Sergey Nivens / fotolia.com)

Transfer of genes between animals and plants has taken place

In the world's largest study of so-called jumping genes, researchers have identified two specific jumping genes in more than 759 species of plants, animals and fungi. These jumping genes are actually small pieces of DNA that can copy through a genome and are known as transposable elements. The experts found that during the evolution a transfer between plants and animals has occurred.

Elements L1 and BovB were examined very closely

The scientists focused particularly on the elements L1 and BovB, which arrived as foreign DNA in mammals. This is the first time that researchers have been able to demonstrate that the L1 element important to humans has jumped between two species.

What is the horizontal transfer of genes?

Jumping genes copy and insert themselves around genomes and into genomes of other species. How they do that is not yet known, although insects such as ticks or mosquitoes or possibly viruses could be involved. Nevertheless, the process remains a mystery, explains study author Professor David Adelson of the University of Adelaide. This process is referred to as a horizontal transfer that differs from the normal parent-child transfer and has a tremendous impact on the evolution of mammals, the expert adds. For example, 25 percent of the genome of cows and sheep are derived from jumping genes.

Horizontal gene transfer is widespread

Imagine jumping genes as a kind of parasite, which is contained in the DNA, says the scientist. This is not so serious, but worse is the fact that jumping genes enter other genomes and disrupt the genes there. Horizontal gene transfer is much more widespread than previously thought. Human L1 elements have been implicated in cancer and neurological disorders. The researchers say that understanding the inheritance of this element is important for understanding the evolution of disease.

Entry of L1 into the mammalian genome was a key factor

The researchers found that L1 occurs in plants and animals. L1 also occurs sporadically in mushrooms. However, the most surprising result was the absence of L1 in two major mammalian species, the Australian monotremes (platypus and echidna). This indicates that the gene has entered the evolutionary pathway of mammals following the departure of monotremes. The entry of L1 into the mammalian genome was arguably a key factor in the rapid evolution of mammals over the last 100 million years, suggested study author Professor Adelson.

These could be the carriers of BovB

In addition, so-called BovB elements were investigated. BovB is a much younger jumping gene. It has already been shown that BovB can jump between a bizarre set of animals including reptiles, elephants and marsupials. Ticks are probably the carriers of cross-BovB transfer. BovB has been transmitted at least twice between frogs and bats, the experts explain. New potential transmitters are bed bugs, leeches and grasshoppers.

Further research is needed

The team believes that insect species research will help to find more evidence of cross-species transfer. They also aim to explore other jumping genes and explore the possibility of aquatic vectors such as sea worms and nematodes. Although recent studies have involved the analysis of genomes from more than 750 species, the scientists themselves have only begun to scratch the surface of horizontal gene transfer. There is much more work to do. (As)