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TOPIC: Primitive life


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RE: Primitive life
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Finding Nematostella: an ancient sea creature shines new light on how animals build an appendage

Theres a new actor on the embryology stage: the starlet sea anemone Nematostella vectensis. Its career is being launched in part by Stowers Institute for Medical Research Associate Investigator Matt Gibson, Ph.D., who is giving it equal billing with what has been his laboratorys leading player, the fruit fly Drosophila melanogaster.
Gibsons lab investigates the cellular and molecular mechanisms used by cells to assemble into layers or clusters during embryogenesis. Those tissues, comprised of densely packed cells known as epithelial cells, shape the body not only of simple creatures but also of mammals, where they line every body cavity from lung to intestine and form hormone- and milk-secreting glands. Unfortunately these cells have a dark side too- over 80% of human cancers, carcinomas, are of epithelial origin.

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SAR11
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A war without end -- with Earth's carbon cycle held in the balance

The greatest battle in Earth's history has been going on for hundreds of millions of years - it isn't over yet - and until now no one knew it existed, scientists reported today in the journal Nature.
In one corner is SAR11, a bacterium that's the most abundant organism in the oceans, survives where most other cells would die and plays a major role in the planet's carbon cycle. It had been theorised that SAR11 was so small and widespread that it must be invulnerable to attack.
In the other corner, and so strange-looking that scientists previously didn't even recognise what they were, are "Pelagiphages," viruses now known to infect SAR11 and routinely kill millions of these cells every second. And how this fight turns out is of more than casual interest, because SAR11 has a huge effect on the amount of carbon dioxide that enters the atmosphere, and the overall biology of the oceans.
 
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Synchrotron Infrared Unveils a Mysterious Microbial Community

A cold sulphur spring in Germany is the only place where archaea are known to dominate bacteria in a microbial community. How this unique community thrives and the lessons it may hold for understanding global carbon and sulphur cycles are beginning to emerge from research at the Advanced Light Source's Berkeley Synchrotron Infrared Structural Biology facility.
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Most simple (early) life forms


In this lecture Kirsi Lehto (University of Turku, Finland) discusses the essential features of cellular life ; what is required for life, and what are the criteria of life. Nucleic acids, genetic code and its expression system are conserved and ubiquitous properties of all life forms, and therefore are assumed to be the most original functional units of life. Molecular analysis of these structures gives suggestions of how they may have been involved in the early molecular evolution, and what functions they may have provided to the early (precellular) replicators.



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Scientists document first consumption of abundant life form, Archaea

A team of scientists has documented for the first time that animals can and do consume Archaea - a type of single-celled micro organism thought to be among the most abundant life forms on Earth.
Archaea that consume the greenhouse gas methane were in turn eaten by worms living at deep-sea cold seeps off Costa Rica and the West Coast of the United States. Archaea perform many key ecosystem services including being involved with nitrogen cycling, and they are known to be the main mechanism by which marine methane is kept out of the atmosphere.
The finding of this new study adds a wrinkle to scientific understand of greenhouse gas cycles.

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Namibia sponge fossils are world's first animals

Scientists digging in a Namibian national park have uncovered sponge-like fossils they say are the first animals, a discovery that would push the emergence of animal life back millions of years.
The tiny vase-shaped creatures' fossils were found in Namibia's Etosha National Park and other sites around the country in rocks between 760 and 550 million years old, a 10-member team of international researchers said in a paper published in the South African Journal of Science.

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The oldest animal fossils

The description by Brain et al. in this issue, of sponge-like organisms from Namibian rocks ranging in age between 760 Ma and 550 Ma, is extremely significant as these organisms represent the earliest record of metazoan life. This discovery places the origin of animals 100 million years to 150 million years earlier than has previously been accepted. That these organisms arose prior to the 'snowball earth' and survived its extremes, presents a challenge to contemporary scientific thought.
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Chinese fossils shed light on the evolutionary origin of animals from single-cell ancestors

Evidence of the single-celled ancestors of animals, dating from the interval in the Earths history just before multicellular animals appeared, has been discovered in 570 million-year-old rocks from South China by researchers from the University of Bristol, the Swedish Museum of Natural History, the Paul Scherrer Institut and the Chinese Academy of Geological Sciences.
All life evolved from a single-celled universal common ancestor, and at various times in Earth history, single-celled organisms threw their lot in with each other to become larger and multicellular, resulting, for instance, in the riotous diversity of animals.  However, fossil evidence of these major evolutionary transitions is extremely rare.

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Alphaproteobacteria
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Unknown ocean bacteria create entirely new theories

The earth's most successful bacteria are found in the oceans and belong to the group SAR11. In a new study, researchers from Uppsala University provide an explanation for their success and at the same time call into question generally accepted theories about these bacteria. In their analysis they have also identified a rare and hitherto unknown relative of mitochondria, the power stations inside cells.
The findings were published in two articles in the prestigious journals Molecular Biology and Evolution and PLoS One in the last week.

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RE: Primitive life
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Bacteria stir debate about 'shadow biosphere'

All life on Earth - from microbes to elephants and us - requires the element phosphorus as one of its six components.
But now researchers have discovered a bacterium that appears to have replaced that life-enabling phosphorus with its toxic cousin arsenic, raising new and provocative questions about the origins and nature of life.
News of the discovery caused a scientific commotion this week, including calls to NASA from the White House asking whether a second line of earthly life has been found.

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Cryogenian period
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Tiny, irregularly shaped fossils from South Australia could be the oldest remains of simple animal life found to date.
The collection of circles, anvils, wishbones and rings discovered in the Flinders Ranges are most probably sponges, a Princeton team claims.
The rocks in which the forms were found are 640-650 million years old.

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