Loki: Missing link in complex life evolution found

NEW DELHI: Scientists have found another missing piece for the jigsaw puzzle of life on earth.

Near a hot spring, over two kilometers deep in the Atlantic Ocean between Norway and Greenland, they found a new type of microbe that is the missing link between organisms like bacteria that have simple type cells and all other life forms from fungi to humans that have complex cells. The new organism is called ‘Loki’, a short form for Lokiarchaeota, named after Loki’s Castle, the place under sea where it was discovered.

The question as to how life progressed from simple cells to the mind-boggling diversity of complex multicellular organisms has long puzzled scientists and this new discovery will help give an answer.

The new study, published in Nature this week, was led by scientists from Uppsala University in Sweden working with those from universities in Bergen (Norway) and Vienna (Austria). It explains how, billions of years ago, the complex cell types evolved from simple microbes.

“The puzzle of the origin of the eukaryotic (complex) cell is extremely complicated, as many pieces are still missing. We hoped that Loki would reveal a few more pieces of the puzzle, but when we obtained the first results, we couldn’t believe our eyes. The data simply looked spectacular”, says Thijs Ettema of Uppsala University, who lead the the study.

“By studying its genome, we found that Loki represents an intermediate form in-between the simple cells of microbes, and the complex cell types of eukaryotes”, says Thijs Ettema.

When Loki was placed in the Tree of Life, this idea was confirmed.

“Loki formed a well-supported group with the eukaryotes in our analyses”, says Lionel Guy, one of the senior scientists involved in the study from Uppsala University.

“In addition, we found that Loki shares many genes uniquely with eukaryotes, suggesting that cellular complexity emerged in an early stage in the evolution of eukaryotes”, says Anja Spang, researcher at Department of Cell and Molecular Biology , Uppsala University, and one of the lead-authors of the study.

Loki was found close to the hostile environment of a hydrothermal vent called Loki’s Castle located on the Mid-Atlantic Ridge between Greenland and Norway at a depth of 2,352 meters.

“Hydrothermal vents are volcanic systems located at the ocean floor. The site where Loki is heavily influenced by volcanic activity, but actually quite low in temperature”, says Steffen Jorgensen from the University of Bergen in Norway, who was involved in taking the samples where Loki was found.

“Extreme environments generally contain a lot of unknown microorganisms, which we refer to as microbial dark matter”, says Jimmy Saw, researcher at Uppsala University, and co-lead author of the paper.

By exploring microbial dark matter with new genomics techniques, Thijs Ettema and his team hope to find more clues about how complex cells evolved.

“In a way, we are just getting started. There is still a lot out there to discover, and I am convinced that we will be forced to revise our biology textbooks more often in the near future”, says Thijs Ettema.

Source: http://timesofindia.indiatimes.com/india/Loki-Missing-link-in-complex-life-evolution-found/articleshow/47185634.cms

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