Archive for março 24th, 2010

A Teoria da Sôpa Primordial Desbancada: mais uma vitória da Matriz/DNA?

quarta-feira, março 24th, 2010

Geyser:Life’s Origins?     geyser_in_yellowstone-national-park.jpg

Geyser: Origens da Vida?         Geyser in Yellowstone Nat. Park


Pantano (Mudpot)

A Teoria da Matriz/DNA sempre sugeriu que os primeiros elementos nas origens da vida vieram da radiação do nucleo terrestre e do espaço principalmente do Sol. Vindo das entranhas da Terra ela passou por muitos caminhos e formas, inclusive pode ter constituido os ventos termais. Agora um novo “paper” fortalece a teoria. Veja o paper:


 New Research Rejects 80-year Theory of ‘Primordial Soup’ as the Origin of Life

02 February 2010  Wiley – Blackwell

Earth’s Chemical Energy Powered Early Life through ‘the most revolutionary idea in biology since Darwin.’

For 80 years it has been accepted that early life began in a ‘primordial soup’ of organic molecules before evolving out of the oceans millions of years later. Today the ‘soup’ theory has been over turned in a pioneering paper in BioEssays which claims it was the Earth’s chemical energy, from hydrothermal vents on the ocean floor, which kick-started early life.

“Textbooks have it that life arose from organic soup and that the first cells grew by fermenting these organics to generate energy in the form of ATP. We provide a new perspective on why that old and familiar view won’t work at all,” said team leader Dr Nick lane from University College London. “We present the alternative that life arose from gases (H2, CO2, N2, and H2S) and that the energy for first life came from harnessing geochemical gradients created by mother Earth at a special kind of deep-sea hydrothermal vent – one that is riddled with tiny interconnected compartments or pores.”

The soup theory was proposed in 1929 when J.B.S Haldane published his influential essay on the origin of life in which he argued that UV radiation provided the energy to convert methane, ammonia and water into the first organic compounds in the oceans of the early earth.  However critics of the soup theory point out that there is no sustained driving force to make anything react; and without an energy source, life as we know it can’t exist.

“Despite bioenergetic and thermodynamic failings the 80-year-old concept of primordial soup remains central to mainstream thinking on the origin of life,” said senior author, William Martin, an evolutionary biologist from the Insitute of Botany III in Düsseldorf. “But soup has no capacity for producing the energy vital for life.”

In rejecting the soup theory the team turned to the Earth’s chemistry to identify the energy source which could power the first primitive predecessors of living organisms: geochemical gradients across a honeycomb of microscopic natural caverns at hydrothermal vents. These catalytic cells generated lipids, proteins and nucleotides giving rise to the first true cells.

The team focused on ideas pioneered by geochemist Michael J. Russell, on alkaline deep sea vents, which produce chemical gradients very similar to those used by almost all living organisms today – a gradient of protons over a membrane. Early organisms likely exploited these gradients through a process called chemiosmosis, in which the proton gradient is used to drive synthesis of the universal energy currency, ATP, or simpler equivalents. Later on cells evolved to generate their own proton gradient by way of electron transfer from a donor to an acceptor. The team argue that the first donor was hydrogen and the first acceptor was CO2.

“Modern living cells have inherited the same size of proton gradient, and, crucially, the same orientation – positive outside and negative inside – as the inorganic vesicles from which they arose” said co-author John Allen, a biochemist at Queen Mary, University of London.

“Thermodynamic constraints mean that chemiosmosis is strictly necessary for carbon and energy metabolism in all organisms that grow from simple chemical ingredients [autotrophy] today, and presumably the first free-living cells,” said Lane. “Here we consider how the earliest cells might have harnessed a geochemically created force and then learned to make their own.”

This was a vital transition, as chemiosmosis is the only mechanism by which organisms could escape from the vents. “The reason that all organisms are chemiosmotic today is simply that they inherited it from the very time and place that the first cells evolved – and they could not have evolved without it,” said Martin.

“Far from being too complex to have powered early life, it is nearly impossible to see how life could have begun without chemiosmosis”, concluded Lane. “It is time to cast off the shackles of fermentation in some primordial soup as ‘life without oxygen’ – an idea that dates back to a time before anybody in biology had any understanding of how ATP is made.”

Obs: Agora vamos fazer uma pesquisa nos detalhes desta noticia, traduzir e retornaremos ao artigo.

Wikipedia:A hydrothermal vent (observar que vent não é vento, é uma fissura, abertura, orificio) is a fissure in a planet’s surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots

Mudpots form in high-temperature geothermal areas where water is in short supply. The little water that is available rises to the surface at a spot where the soil is rich in volcanic ash, clay and other fine particulates. The thickness of the mud usually changes along with seasonal changes in the water table.

Wikipedia: Hydrothermal origin of life

Günter Wächtershäuser proposed the Iron-sulfur world theory and suggested that life might have originated at hydrothermal vents. Wächtershäuser proposed that an early form of metabolism predated genetics. By metabolism he meant a cycle of chemical reactions that produce energy in a form that can be harnessed by other processes.[15]

It has been proposed that amino-acid synthesis could have occurred deep in the Earth’s crust and that these amino-acids were subsequently shot up along with hydrothermal fluids into cooler waters, where lower temperatures and the presence of clay minerals would have fostered the formation of peptides and protocells.[16] This is an attractive hypothesis because of the abundance of CH4 and NH3 present in hydrothermal vent regions, a condition that was not provided by the Earth’s primitive atmosphere. A major limitation to this hypothesis is the lack of stability of organic molecules at high temperatures, but some have suggested that life would have originated outside of the zones of highest temperature. There are numerous species of extremophiles and other organisms currently living immediately around deep-sea vents, suggesting that this is indeed a possible scenario.