TECH-HEALTH: BERLIN – Mutant crayfish that clones itself may help unlock cancer secrets

Scientists are hoping the rapidly spreading crustacean could help unlock some of the secrets of cancer



THE marbled crayfish is a modern evolutionary anomaly. The all-female crustacean, named for the marbled pattern on its shell, didn’t even exist 25 years ago. Now, thanks to its ability to clone itself, it numbers in the billions.

About six inches long on average, the freshwater crustacean was first spotted in Germany in the 1990s. Since then, the species has spread so quickly that it has now been banned in Europe, and has even been found as far as afield as Madagascar, Japan and Canada.

Now, scientists are hoping the rapidly spreading crustacean could help unlock some of the secrets of cancer.

Researchers from the German Cancer Research Centre (DKFZ) recently sequenced the genome of the marbled crayfish, and say it’s consistent with their theory that the invasive freshwater crustacean was created when two slough crayfish mated.

One must have had a mutant egg or sperm cell that retained two copies of its chromosomes instead of the usual one, they believe.

The billions of marbled crayfish worldwide today can be traced to a single female from that union, the scientists wrote in the London-based journal Nature Ecology and Evolution.

The crayfish reproduce asexually by what is known as parthenogenesis. That means they lay unfertilised eggs that develop under the influence of certain hormones into genetically identical offspring – full clones of the mother.

“It will be interesting to further explore marbled crayfish as a model system for clonal genome evolution in cancer,” the scientists say, noting that the creature’s development could offer an insight into how a normal cell turns cancerous and begins generating clones of itself.

For their study, the scientists sequenced the genomes of 11 marbled crayfish, scientifically known as Procambarus virginalis. Some were from German pet shops, others from the wild in Germany, others from Madagascar. The genomes were identical.

Madagascar has proved an especially fertile home for the species. Abetted by the relatively high temperatures and dense network of freshwater habitats there, it has grown so much that it now threatens rice crops, ecosystems and seven indigenous crayfish species.

While aphids, water fleas and some species of fish and lizards reproduce by parthenogenesis, the marbled crayfish is the only known decapod – or ten-legged – crustacean to do so. The animals are prolific, laying as many as 500 eggs every 12 weeks.

A single marbled crayfish is sufficient to create a new population. And since they reproduce so quickly, aquarium hobbyists have probably released a fair few into the wild or flushed them down the toilet.

They’re a serious threat to indigenous crayfish species, experts say, because they compete with them for food and space, and may also transmit crayfish plague, a lethal water mould.

Field research done in connection with the genome study, led by DKFZ molecular biologist Frank Lyko and bioinformatician Julian Gutekunst, found that the habitat of marbled crayfish in Madagascar has increased from 1,000 square kilometres to 100,000 in just 10 years.

With sexually reproducing animals, such a wide variety of habitats would lead to genetically adapted subspecies. Marbled crayfish, however, are all clones with the same genes.

Instead, they adapt with the help of so-called epigenetic mechanisms – small chemical tags that attach to their DNA and work like switches that turn genes “on” or “off.”

This epigenetic regulation makes marbled crayfish extremely interesting for tumour researchers, says Lyko, who heads the DKFZ’s Division of Epigenetics.

Tumours are also able to adapt to their environment – by developing resistance to anti-cancer drugs, for example – and epigenetic mechanisms play a key role in tumour growth.

Lyko and his colleagues hope that closer study of the marbled crayfish will lead to new approaches in cancer treatment. – Text & Photo by dpa / Borneo Bulletin / March 31, 2018     |     Alice Lanzke     |All photographs, news, editorials, opinions, information, data, others have been taken from the Internet | [email protected] | For comments, Email to : |

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