Researchers found that humans share more genes with a slimy seabed worm, compared to any other animals.
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Rokhsar, who heads OIST’s Molecular Genetics Unit as a visiting professor, and Nori Satoh, head of OIST’s Marine Genomics Unit, led the project in which they found the newly sequenced genomes of two marine worms shedding light on the 570 million-year evolution of gills into the pharynx that today gives humans the ability to bite, chew, swallow and speak.
Researchers have sequenced the genomes of two species of small water creatures called acorn worms, and have found that humans may have more in common with them than first thought.
In addition to sequencing the two acorn worms in this latest study, the researchers also identified ancient gene families that were already present in the deuterostome ancestor.
Scientists believe our wormy ancestry can be traced back to the Cambrian explosion, a surge in evolutionary diversity that occurred about 550 million years ago.
It is not only that humans contain the genes from the ancient ancestor, but all animals with backbones and also cephalopods (octopus and squid) and sea stars.
Of all deuterostomes alive now, acorn worms have been around the longest. “Acorn worms look very different from chordates, which makes it especially surprising that they and chordates, like humans, are so similar on the genomic, developmental and cell biological levels”. This happens even in species as different as acorn worms and humans.
As deuterostomes evolved, many species emerged that were more complex than their acorn-worm cousins. But even in later species, a few physical features can still be linked to genes in acorn worms for simpler structures that perform the same jobs, Simakov and his colleagues found. “Acorn worms are marine invertebrates that, despite their decidedly non-vertebrate form, are nevertheless among our closest invertebrate relatives”.
An adult female acorn worm, Saccoglossus kowalevskii, with eggs. These genes were particularly interesting to the scientists, they said.
The discovery explains why acorn worms have specialized slits near their gut regions, found between their mouth and esophagus. The slits in the animal plays an important role in its digestive system. Therein the study found that about 8,600 families of genes are homologous across all deuterostomes, all the way back to the first deuterostome.
For future studies, the researchers said they will expand genomic analysis and include more under-sampled regions across the sprawling tree of life.
The finding is detailed November 18 in the journal Nature.
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