Irish scientists uncover 'Nature's big bang'

Black yeast fungi
Image caption Insects, plants, animals and humans are all eukaryotes

Scientists in Ireland have said they have unravelled the mystery of how complex life formed.

Researchers led by a team from the National University of Ireland (NUI) in Maynooth announced on Wednesday that they have identified the moment when two single-celled organisms combined to become the ancestor of all multi-cellular life on earth.

Dubbed "Nature's big bang" the event saw the fusing of two cells into the first cell with a nucleus.

Dr James McInerney, senior biologist at Maynooth, said the work had in a sense tracked down humanity's oldest ancestor.

"This was a remarkable event, which appears to have happened only once," Mr McInerney said.

"These two primitive single-celled life forms came together in an event that essentially allowed nature to grow big."

Dr McInerney said the research would help to explain the origin of all the multi-cellular organisms.

First nucleus

Insects, plants, animals and humans are all considered to be complex multi-cellular organisms called eukaryotes.

Eukaryotes are one of the three top-level categories of life called domains. The other two domains are bacteria and the bacteria-like archaea.

Using genetics and information from the mapping of the yeast genome, evidence of both a bacterial cell and an archaean cell, were discovered inside a eukaryote which formed with a nucleus.

This meant that the yeast was basically the "child" of a bacterium and an archaean. Which also makes us their descendants.

Dr McInerney said: "It is in the nucleus that we find the DNA of all species, and for years it had been a puzzle as to how the first nucleus was created. Now we know."

The first eukaryotes are believed to have appeared about two billion years ago.

Dr McInerney, of NUI Maynooth's Bioinformatics and Molecular Evolution Unit of the Department of Biology, collaborated with Dr James Cotton at the Sanger Institute in Cambridge, England, to carry out the research.

The discovery was made after 10 years of research at NUI Maynooth and followed the sequencing of the yeast genome in 1997.

Their work has been published in the eminent Proceedings of the National Academy of Sciences, USA.

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