1.
SCIENTISTS DISCOVER FIRST MULTICELLULAR LIFE THAT DOESN'T NEED OXYGEN
By Lisa Zyga
PhysOrg.com
April 7, 2010
http://www.physorg.com/news189836027.html
Oxygen may not be the staple of modern complex life that scientists once thought. Until now, the only life forms known to live exclusively in anoxic conditions were viruses, bacteria, and Archaea. But in a new study, scientists have discovered three new multicellular marine species that appear to have never lived in aerobic conditions, and never metabolized oxygen.
The discovery of the new species, which live buried in sediment under the Mediterranean seafloor, is significant in that it marks the first observation of multicellular organisms, or metazoans, that spend their entire lifecycle under permanently anoxic conditions. A few metazoans have been known to tolerate anoxic conditions, but only for limited periods of time.
The team of Italian and Danish researchers, Roberto Danovaro, et al., that discovered the new life forms has identified the creatures as belonging to the animal phylum Loricifera, the most recently described animal phylum. Loriciferans, which have a length of less than one millimeter, typically live in sediment. The three new organisms belong to different genera (Spinoloricus, Rugiloricus, and Pliciloricus), although their species have not yet been named.
Despite belonging to previously known taxonomic groups, the new species possess some radical differences compared with other metazoans. Most significantly, the new species do not have mitochondria, the cellular organelles that use oxygen and sugar to generate the cell’s energy. Instead, the new loriciferans have organelles that resemble hydrogenosomes, which are used by some single-celled eukaryotes to generate energy without oxygen. However, this is the first time that these organelles have been observed in multicellular organisms. Previous research has indicated that hydrogenosomes may have evolved from mitochondria, while other research suggests they evolved independently.
To find the new species, the researchers carried out three oceanographic expeditions from 1998 to 2008 to search for life in the extreme environments located more than 3,000 meters (about two miles) under the Mediterranean Sea. The researchers focused on an area called the L’Atalante basin, which is located off the southern coast of Greece. As the scientists explain, this type of “deep hypersaline anoxic basin” was created by the flooding of mineral sediments from 5.5 million years ago. For the past 50,000 years, the basin has possessed a dense hypersaline brine layer up to 60 meters thick. The brine serves as a physical barrier that prohibits oxygen exchange between the water and sediment, making the basin completely oxygen-free. In addition, the basin is rich in methane and hydrogen sulphide, and is also home to a diverse assembly of prokaryotes that have adapted to these conditions.
Because previous studies have reported the presence of cadaverous metazoans that had sunk to anoxic deep-sea sediments in the Black Sea, the researchers here stained the newly collected specimens with Rose Bengal, a protein binding stain that colors living organisms with a much greater intensity than deceased organisms, demonstrating that the new species were indeed alive. In addition, the scientists observed specimens of the undescribed species of both genera Spinoloricus and Rugiloricus that had a large oocyte in their ovary, which showed a nucleus containing a nucleolus, providing evidence of reproduction.
“The results reported here support the hypothesis that the loriciferans inhabiting the anoxic sediments of the L’Atalante basin have developed an obligate anaerobic metabolism and specific adaptations to live without oxygen,” the researchers conclude. “Although the evolutionary/adaptative mechanisms leading to the colonization of such extreme environments by these metazoans remain an enigma, this discovery opens new perspectives for the study of metazoan life in habitats lacking molecular oxygen.”
The work is financially supported by the E.U. within the framework of the HERMES (Hot Spot Ecosystem Research on the Margins of European Seas) and HERMIONE (Hotspot Ecosystem Research and Man's Impact On European Seas) projects.
More information: Roberto Danovaro, et al. “The first metazoa living in permanently anoxic conditions.” BMC Biology 2010, 8:30 doi:10.1186/1741-7007-8-30.
2.
News
ANIMALS THRIVE WITHOUT OXYGEN AT SEA BOTTOM
By Janet Fang
Nature News
April 6, 2010
http://www.nature.com/news/2010/100406/full/464825b.html
Living exclusively oxygen-free was thought to be a lifestyle open only to viruses and single-celled microorganisms. A group of Italian and Danish researchers has now found three species of multicellular animal, or metazoan, that apparently spend their entire lives in oxygen-starved waters in a basin at the bottom of the Mediterranean Sea.
The discovery "opens a whole new realm to metazoans that we thought was off-limits", says Lisa Levin, a biological oceanographer at Scripps Institution of Oceanography in La Jolla, California.
Roberto Danovaro from the Polytechnic University of Marche in Ancona, Italy, and his colleagues pulled up the animals during three research cruises off the south coast of Greece. The species, which have not yet been named, belong to a phylum of tiny bottom-dwellers called Loricifera. Measuring less than 1 millimeter long, they live at a depth of more than 3,000 meters in the anoxic sediments of the Atalante basin, a place so little explored that Danovaro likens his team's sampling to "going to the Moon to collect rocks."
Researchers have previously found multicellular animals living in anoxic environments, but Danovaro says that it was never clear whether those animals were permanent residents. The new loriciferans, which he and his team reported this week (R. Danovaro et al. BMC Biol. doi:10.1186/1741-7007-8-30; 2010), seem to "reproduce and live all their life in anoxic conditions," he says.
The researchers identified an adaptation that helps these loriciferans to survive in their environment. Instead of mitochondria, which rely on oxygen, the creatures have organelles that resemble hydrogenosomes, which some single-celled organisms use to produce energy-storing molecules anaerobically.
Angelika Brandt, a deep-sea biologist at Germany's Zoological Museum in Hamburg, says that the work by Danovaro's group is "highly significant." The discovery of metazoans living without mitochondria and oxygen, she says, suggests that animals can occupy niches that once seemed too extreme.
3.
ANIMALS THAT CAN LIVE WITHOUT OXYGEN DISCOVERED, ALIENS BASICALLY GUARANTEED TO EXIST NOW
By Adam Frucci
Gizmodo.com
April 8, 2010
http://www.gizmodo.com.au/2010/04/animals-that-can-live-without-oxygen-discovered-aliens-basically-guaranteed-to-exist-now/
Scientists have just discovered the first multicellular animals that can survive entirely without oxygen. They live in the L’Atalante Basin in the Mediterranean Ocean, a place with salt brine so thick it doesn’t mix with oxygen-containing waters above.
This is pretty crazy stuff. Previously, it was thought that only single-celled life could exist in such inhospitable places, but this proves otherwise.
The animals took up radioactively tagged leucine (an amino acid), and a fluorescent probe that labels living cells, evidence that they were alive when they were collected. The researchers also found examples of individuals that contained eggs and evidence of apparent molting, which led them to conclude that the animals spend their whole lives in the harsh sediments. The creature’s cells apparently lack mitochondria, the organelles that use oxygen to power a cell. Instead they are rich in what seem to be hydrogenosomes, organelles that can do a similar job in anaerobic (or oxygen free) environments.
This is interesting not only for the study of our oceans, but for life off our planet as well. After all, if life can exist where there’s no oxygen, what’s to say life can’t exist in some of the harsher atmospheres that exist on other planets and moons? And at this point, why the hell haven’t they contacted us yet? Are we not ready? Just tell us what to do, space friends! Come on!
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