Science

Single gene that causes a rightward swirl in snails' shells identified


Scientists have discovered why snail shells coil to the right.

They say the breakthrough could also explain why our hearts are on our left and livers on our right.

‘Lefty’ snails are rarely found in nature and are shunned as mating partners.

Jeremy the ‘lefty’ snail’s failed hunt for love went viral on social media in 2017 while Brian – of The Magic Roundabout fame – had a normal shell that let him enjoy free love.

Japanese researchers have now identified a single gene that caused rightward chirality in the Lymnaea stagnalis freshwater snail. 

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Scientists have discovered why snail shells coil to the right (pictured). They say the breakthrough could also explain why our hearts are on our left and livers on our right.

Scientists have discovered why snail shells coil to the right (pictured). They say the breakthrough could also explain why our hearts are on our left and livers on our right.

Snails genetically engineered without a functional version of the Lsdia1 gene produced offspring with shells that coiled to the left, their study found.

The researchers believed the reason behind asymmetry in different species was probably the same – suggesting a similar process exists in humans.

Study author Professor Reiko Kuroda, 71, of the University of Tokyo in Japan, said: ‘It is remarkable that these snails with reversed coiling are healthy and fertile, and that this coiling can be inherited generation after generation, we now have 5th-generation leftward-coiling snails.

‘Further, these results may have an implication for snail evolution and speciation – given that left- and rightward-coiling snails probably wouldn’t interbreed.’

Her research team were ‘surprised’ to see could see signs of ‘lefty’ shells when the snail embryos were just a single cell.

And when the mutant snails could be reared to adults, they produced exclusively leftward-coiling offspring.

Professor Kuroda said while it was not yet clear how Lsdia1 could control left-right asymmetry, the gene encodes a ‘formin’ protein involved in regulating the cell’s internal skeleton.

And given that genes like Lsdia1 are found throughout the animal kingdom, similar mechanisms for controlling left-right asymmetry could be at play in other species – including our own.

'Lefty' snails are rarely found in nature and are shunned as mating partners. Japanese researchers have now identified a single gene that caused rightward chirality in the Lymnaea stagnalis freshwater snail

‘Lefty’ snails are rarely found in nature and are shunned as mating partners. Japanese researchers have now identified a single gene that caused rightward chirality in the Lymnaea stagnalis freshwater snail 

Professor Kuroda said: ‘Although diverse mechanisms have been proposed for different animals, we think a unified mechanism, involving formins and cellular chirality, is probable’.

The professor and her colleagues are conducting further research on how the gene influences the cellular behaviours that control handedness.

She said studying Lsdia1 could eventually help understand why some babies are born with their heart on the right side of their chest.

The findings were made after the research team successfully applied CRISPR gene editing technology to molluscs for the first time.

Jeremy the ‘lefty’ snail’s failed hunt for love was the romantic match that captured the hearts of the nation.

Jeremy the 'lefty' snail's failed hunt for love was the romantic match that captured the hearts of the nation in 2017. Jeremy (pictured) had a one in a million genetic anomaly that made his shell swirl to the 'sinister' left, rather than the right

Jeremy the ‘lefty’ snail’s failed hunt for love was the romantic match that captured the hearts of the nation in 2017. Jeremy (pictured) had a one in a million genetic anomaly that made his shell swirl to the ‘sinister’ left, rather than the right

However, his days of chasing love are sadly now over, after the snail died in October of 2017.

A rare mutation meant Jeremy’s shell coiled from left to right – making sex with a common snail impossible because his genitals were on the wrong side. 

The gallant ‘lefty’ gastropod, however, finally found another ‘lefty’ to start a family with a former love rival, becoming a ‘father’ to around 100 tiny snail babies.

But the news was tinged with sadness as scientists, fascinated by his discovery in a London compost heap in 2016,  said the snail died shortly afterwards. 

Jeremy was rescued from a compost heap in London, and the ‘left handed’ snail was plucked from obscurity and recognised as one of a kind.

Researchers at the University of Nottingham had almost given up on Jeremy's (pictured top) chances for children, after he was bested in a love triangle in June 2017. Jilted Jeremy was matched with two other rare snails, Lefty and Tomeau, who instead mated with each other

Researchers at the University of Nottingham had almost given up on Jeremy’s (pictured top) chances for children, after he was bested in a love triangle in June 2017. Jilted Jeremy was matched with two other rare snails, Lefty and Tomeau, who instead mated with each other

After discovering his shell swirled the ‘wrong’ way compared to other snails, scientists put out a call in October 2016 to find the mollusc a mate to preserve his genetic legacy.

The search turned up Lefty in Ipswich and Tomeau, who was flown into the UK from a snail farm in Majorca.

The threesome was given to the University of Nottingham, who believe that studying the genetic variations which cause the unique shell formations may shed light on a rare heart condition in humans.

Despite some initial interest between Jeremy and Lefty, it seems the exotic charms of the Spanish visitor were more to Lefty’s tastes. 

The findings were published in the journal Development.

WHO WAS JEREMY THE ‘LEFTY’ SNAIL?

 Jeremy the ‘lefty’ snail’s failed hunt for love was the romantic match that captured the hearts of the nation in 2017.

Jeremy was rescued from a compost heap in London and scientists put out a call in to find the mollusc a mate who shared the same left swirling shell pattern.

Two potential candidates were found and the threesome was given to the University of Nottingham in the hopes that they would have similar ‘lefty’ babies.

Scientists believe the snail’s unique swirls are related to a human heart condition called dextrocardia, which is thought to affect one in 10,000 people.

Despite some initial interest between Jeremy and Lefty from Ipswhich, it seems the exotic charms of Spanish visitor Tomeau were more to Lefty’s tastes.

The pair had 170 babies during their initial get together, although none of the offspring so far has shared the left-swirls of their parents. 

Snails are hermaphrodites so can reproduce on their own without the need for another mate. 

But the molluscs only do this in the absence of a suitable mate, preferring to hook up with another snail. 

Researchers say the data from offspring of two lefty snails would also be far more valuable for genetic studies.

Scientists believe lefty snail’s unique swirls are related to a condition called dextrocardia, in which patients have their heart on the wrong side of their chest.

The same genes are believed to cause snails’ shells to twist round the wrong way.

They hope is that by mating two ‘left-handed’ snails, scientists can zero in on the genes responsible for their altered body plan. 

This may also shed light on the heart condition, which is thought to affect one in 10,000 people.

 



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