Same genes behind left-right asymmetric bodies in human and snail

December 22nd, 2008 - 12:48 pm ICT by ANI  

London, December 22 (ANI): Researchers at the University of California, Berkeley have found that the genes, which are responsible for the differences in the internal structures of the left and right sides of human bodies, also control the handedness of snail shells.
Most people’’s hearts are towards the left side of the body, which means the left lung is slightly smaller to make room for it, and the intestines are arranged in an asymmetric coil.
While some people have their insides flipped, their overall internal arrangement is a mirror image of the norm.
Professor Nipam H. Patel and post-doctoral fellow Cristina Grande have identified a gene called “nodal” that, in all vertebrates checked to date, is expressed on the left side of the body and necessary to set up left-right asymmetry.
The researchers have revealed that knocking out nodal causes internal organs are jumbled, and the organism dies.
“In vertebrates, a set of genes tells the body it has to form a heart toward one side, and nodal is one of those genes,” Nature magazine quoted Grande, who recently took a position at the Centro de Biologia Molecular “Severo Ochoa” in Madrid, Spain, as saying.
“There are a lot of asymmetric molecules in the body, that is, molecules that are active on only one side of the body, but nodal is always expressed on the left side in all vertebrates, which is evidence of a conserved pathway,” Patel added.
While searching for genes similar to nodal in the right-handed snail, the marine limpet Lottia gigantea, the researchers found one that was analogous to the gene Pritx, which is activated by nodal and also involved in setting up left-right asymmetry in vertebrates.
Grande also used that information to find similar genes in the left-handed snail Biomphalaria glabrata, the fresh-water host of the parasite that causes schistosomiasis.
She said that the experiments showed that nodal and Pitx were active or expressed on the right side of embryos in the right-handed snail Lottia, and on the left side in the left-handed snail Biomphalaria.
The researchers believe that their findings may help to track down the ultimate cause of symmetry-breaking in snails and other organisms, and the cascade of gene activation that leads to complex shapes, such as coiled shells. (ANI)

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