They reveal how a platense snail has become a dreaded global scourge

Forty years ago, the snail or apple, a species native to the Plata Basin, had been taken to the island of Taiwan for cultivation as food and had finally expanded to no one. could imagine. Over the past decade, it has already spread to natural environments in Japan, the Philippines, China, Korea, Indonesia, Thailand, Laos and Vietnam. And a few years later, it also invades the Delta of the Ebro, the southern United States and even northern Russia, becoming in many cases the main scourge of rice crops.

But besides being a global nightmare for rice farmers, this species (which is usually found in Lake del Bosque with its characteristic pink eggs) has a great capacity to modify the natural ecosystems where it lives, resulting in a significant loss of biodiversity. species. And as if that was not enough, it also hosts parasites that can cause meningoencephalitis in humans.

Faced with this situation, an international initiative involving scientists from La Plata has succeeded in sequencing the genome of the species, which "makes it possible to know in detail the genes that would explain its success as an invader and would make it a target. 'attack for his control,' said at the agency Cyta-Leloir, Dr. Horacio Heras of the Institute of Biochemistry Research of La Plata (INIBIOLP), one of the authors of the 39; study.

The work – led by scientists from the Hong Kong Baptist University and published in the scientific journal "Molecular Biology and Evolution" – revealed that the ampullary snail has just over 18,000 genes, among which those of a family appear very clearly It fulfills an essential function: it allows the digestion of abundant cellulose fibers in the plants.

This is an "unexpected discovery" because "the vast majority of animals do not even have genes for digesting cellulose," said the director of the INIBIOLP's Comparative Biochemistry Group.

This particular feature, however, is not the only strategy to use to relentlessly flee: scientists have discovered in their genome an increased number of copies of two genes containing information to synthesize a single toxin in the animal. This toxin accumulates in large quantities in eggs, thus protecting embryos from predators.

"That would explain why no one eats them, a feature that enhances their success as an invader," said Heras, also a researcher at CONICET and a professor of biological chemistry at the Faculty of Natural Sciences and Museum of Science. ; UNLP.

Forty years ago, he was taken to Taiwan for food and found himself out of control

However, the discovery of these genes "is just the tip of the iceberg," says Dr. Heras, who hopes that this knowledge will be translated in the future as a tool to stop the progression of the snail. "We are generating new information to locate your Achilles heel," said the researcher.

The history of the snail is another example of an environmental, economic and health disaster that can be caused by the introduction of exotic species into habitats devoid of natural predators, thus opening a kind of environmental Pandora box.

THE MULTI CARACOL RESISTANT

The fact that it has spread so much around the world is also attributed to some of the "super powers" that these snails have from our region's origin.

For example, they are very resistant to adverse environmental conditions due to a combination of biochemical, anatomical, physiological and behavioral characteristics.

They survive for weeks and even months after drying, low oxygen levels in the water and starvation. And in addition to the gills that allow them to draw oxygen from the water, they have a kind of lung that reaches the air sucked in by a long tube called "siphon", similar to a dive in apnea. Thus, the combination of quasipulmon and gill is an evolutionary adaptation to habitats where the water is poor in oxygen.

Its resistance is such that its progress in Asia has earned it one of the top 100 most harmful invasive alien species in the world.