Humans Share 70 Percent of Their Genes With Atlantic and Pacific Ocean Acorn Worms

Summary: Apparently humans share 70 percent of their genes with two Atlantic and Pacific Ocean acorn worms, according to a study published in Nature Nov. 18, 2015.

"Caption The acorn worm Saccoglossus kowalevskii is common in brackish, shallow water on the Atlantic coast. Its newly sequenced genome is telling biologists about the genes responsible for pharyngeal gills in the hemichordates and chordate structures such as the pharynx, which in humans includes the jaws, tongue, voicebox and various glands and muscles between the mouth and throat."; credit Chris Lowe, Stanford University: No usage restrictions, via EurekAlert!

Humans appear to share 70 percent of their genes with two Atlantic and Pacific Ocean acorn worms, according to a study published online Nov. 18, 2015, in the open-access journal Nature.

The 61 co-authors base their findings upon the results of genome sequencing for two species, Ptychodera flava off Hawaii and Saccoglossus kowalevskii in the Atlantic Ocean. The entire genetic material from each of the two marine worms with acorn-shaped heads can be compared with other sequenced genomes, such as that of humans. The comparison of the genomes of people and the worms describes a 70 percent match on 14,000 of the human total of 20,000 to 25,000 genes.

The results expose a common shared ancestry.

Research co-leaders Takashi Kawashima in Marine Genomics and Oleg Simakov in Molecular Genetics at the Okinawa Institute of Science and Technology in Japan find deuterostomal lineages.

Scientists give the name deuterostomes (“mouth second” literally, because the anal opening develops before the oral) to all of that ultimate ancestor’s backboned and spineless descendants. Oleg Simakov, study corresponding author, holds: “Acorn worms are our most ancient deuterosome relatives, dating back to the origin of deuterostomes, around 570 million years ago.”

The comparative genome sequencing of acorn worms, people and 32 animals indicates that all deuterostomes appear to share the same 8,716 gene families (similar gene sets).

The co-researchers judge particularly research-worthy a deuterostome-only gene cluster regarding breathing and feeding.

Scientists know of only deuterostome group members as having specialized slits near the esophagus to let water bypass the digestive tract and circulate through the mouth. The co-researchers link the genes that control specialized feeding in acorn worms to those that develop gills in some deuterostomes and pharynxes and thyroids in others. Seventy percent genomic overlaps may not produce similar physical features when the controlling genes let complex human structures and simple worm structures get similar jobs done.

Daniel Rokhsar of Okinawa Institute’s Molecular Genetics Unit notes: “The presence of these slits in acorn worms and vertebrates tells us that our last common ancestor also had them, and was likely a filter feeder like acorn worms today.

Further research offers insights into only humans and other deuterostomes sharing with algae and bacteria 12-plus genes affecting protein modification and secondary and sialic acid metabolisms. It promises to help reconstruct genetic divergence paths from the original shared deuterostome ancestor by sequencing the genomes of other chordate (back-supported) and echinoderm (hedgehog-skinned) descendants. The combined expertise and cumulative experiences qualify the 61 co-researchers for answering these and other evolutionary questions by “defining the deuterostome ancestor and illuminating chordate origins.”

Research into the original deuterostome ancestor raises questions regarding the ultimate human ancestor, Mitochondrial Eve of 140,000 years ago and Y-chromosomal Adam of 338,000 years ago.

Genome-sequencing serves to close the 232,000-year gap between emergences of deuterostomes and humans.

inch-long acorn worm, with slits highlighted; photo by Casey W. Dunn courtesy of Nature: UC Berkeley News @UCBerkeleyNews, via Twitter Nov. 19, 2015

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

"Caption The acorn worm Saccoglossus kowalevskii is common in brackish, shallow water on the Atlantic coast. Its newly sequenced genome is telling biologists about the genes responsible for pharyngeal gills in the hemichordates and chordate structures such as the pharynx, which in humans includes the jaws, tongue, voicebox and various glands and muscles between the mouth and throat."; credit Chris Lowe, Stanford University: No usage restrictions, via EurekAlert! @ https://www.eurekalert.org/multimedia/900358; (EurekAlert! news release URL @ https://www.eurekalert.org/news-releases/765529); (former URL @ http://www.eurekalert.org/pub_releases/2015-11/uoc--awg111915.php)

inch-long acorn worm, with slits highlighted; photo by Casey W. Dunn courtesy of Nature: UC Berkeley News @UCBerkeleyNews, via Twitter Nov. 19, 2015, @ https://twitter.com/UCBerkeleyNews/status/667419714696671233

For further information:

Bhatia, Guneet. 20 November 2015. "Humans Share 70 Percent Of Their Genes With This Slimy Seabed Worm." International Business Times.
Available @ http://www.ibtimes.com/humans-share-70-percent-their-genes-slimy-seabed-worm-2193289

Doctor, Rina Marie. 19 November 2015. "Genome Sequencing Reveals Slimy Seabed Worms Share 70 Percent Of Human Genes." Tech Times.
Available @ http://www.techtimes.com/articles/108398/20151119/genome-sequencing-reveals-slimy-seabed-worms-share-70-percent-of-human-genes.htm

Feltman, Rachel. 19 November 2015. "This weird worm is a surprisingly close cousin of ours." The Washington Post > News > Speaking of Science.
Available @ https://www.washingtonpost.com/news/speaking-of-science/wp/2015/11/19/this-weird-worm-is-a-surprisingly-close-cousin-of-ours/

Reuters. 18 November 2015. "Worm species is distant human relative." YouTube.
Available @ https://www.youtube.com/watch?v=lyr0j8Kutw0

Sanders, Robert. 19 November 2015. "Acorn worm genome reveals gill origins of human pharynx." Berkeley News > Mind & Body, Research, Science & Environment.
Available @ http://news.berkeley.edu/2015/11/19/acorn-worm-genome-reveals-gill-origins-of-human-pharynx/

Simakov, Oleg, et al. "Hemichordate genomes and deuterostome origins." Nature 527 (Nov. 26, 2015): 459-465. DOI: 10.1038/nature16150
Available @ http://www.nature.com/nature/journal/v527/n7579/full/nature16150.html

UC Berkeley News @UCBerkeleyNews. 19 November 2015. "We diverged from the acorn worm 570 million years ago. Here's what became of our gills." Twitter.
Available @ https://twitter.com/UCBerkeleyNews/status/667419714696671233

University of California-Berkeley. 19 November 2015. "Acorn worm genome reveals gill origins of human pharynx." EurekAlert! > Public Releases.
Available @ http://www.eurekalert.org/pub_releases/2015-11/uoc--awg111915.php

Weisberger, Mindy. 18 November 2015. "You Share 70% of Your Genes with This Slimy Marine Worm." LiveScience > Animals.
Available @ http://www.livescience.com/52843-acorn-worm-genome-sequencing.html