To conduct their experiments, the researchers built a special atmospheric chamber, which they dubbed LISA (an acronym for Italian Laboratory for Environmental Simulation). The LISA chamber(s) could be programmed to produce a variety of atmospheric pressures, humidity conditions, temperatures, and radiation (UV) levels. Various conditions that reflected known conditions on Mars were reproduced and various species of bacteria (as bacterial cells and as spores) were kept in the environments for different lengths of time. The samples were then tested for the ability to resume growth (in essence, come back to life when re-plated on a favorable growing surface).

As on Earth, bacteria can be very resistant to cold. When stressed, many kinds of bacteria produce an endosperm (spore) from which all water has been removed. These are particularly impervious to cold. Similarly, pressure change has little effect, nor does humidity (especially relative to the very cold temperatures). Conditions on Mars are relatively brutal, with temperatures running from 20C on the high end to -80C on the low end. There is little to no moisture available in the atmosphere or at the immediate surface. Pressure changes are by Earth standards abrupt and dramatic. However, individually the extremes had little impact on spores and even some of the living cells were able to survive.

Adding intense UV radiation to the mix of conditions was decisive. The intensity of unfiltered ultraviolet light that bombards the surface of Mars is unknown on Earth, and it is fatal for nearly all forms of bacteria. The combination of UV with some of the other conditions, especially cold, was usually fatal; however, some bacteria survived hours and one species survived 28 hours – a remarkable toughness.

Perhaps the key element of the study was the introduction of a coating of fine dust (simulated by volcanic powder and iron oxide). This is a condition that would be very common on Mars, where the global winds and massive storms carry dust clouds everywhere. It was found that even a very thin coating was sufficient to protect most bacteria species from UV radiation. This meant that even in today’s conditions, it is possible that bacteria may survive on Mars and may possibly revivify whenever enough warmth and moisture are available.

The researchers were careful to point out that these are experiments with Earth microbes. There is no evidence for any bacteria on Mars, as yet. There is also no way to tell, without specimens, if Martian microbes are like those on Earth. If, as the hypothesis called panspermia is correct, then bacteria may have been wafted among the stars, moons, and planets on debris thrown out by meteorite impacts. In such a way, life could have migrated from Mars to Earth or vice versa. If so, then the types of bacteria – their molecular composition and DNA – should be similar, and tests like the Italians used should be valid. However, if life arose independently on Mars, there would be its own version of LUCA (Last Universal Common Ancestor). Such life might have substantially different biochemical composition – possibly one not even detectable by our earthly biological devices.

The Italian experiments are part of an ongoing research into the nature and living conditions of extremophiles, forms of life that exist under extreme conditions – in volcanic vents, under glaciers, at the bottom of oceans, and even inside rocks. In this case, the experiments relate to Mars; but in the broader picture what they discover, at least in the case of life forms with similar biochemical makeup to that of Earth, could be applicable to many other locations in our solar system, including the moons Io, Titan, Europa, and Enceladus.

Terrestrial lifeforms show a strong capability to adapt to very harsh environments and to survive even to strong shocks as those
derived from meteorite impacts. These findings increase the possibility to discover traces of life on a planet like Mars, that had past
conditions similar to the early Earth but now is similar to a very cold desert, irradiated by intense solar UV light.

[Source: arXiv]

Just how seriously challenged, we shall see. The new hypothesis was worked out by essentially three people at three institutions: Nick Lane, Department of Genetics, Evolution, and Environment, University College London (UK), John F. Allen, School of Biological and Chemical Sciences, Queen Mary University of London (UK), and William Martin, Institut für Botanik III, Heinrich-Heine-Universität (Germany). Their paper, How did LUCA make a living? Chemiosmosis in the origin of life, will be formally published in the March issue of BioEssays (and is available online now).

LUCA is not a familiar acronym; in biology it stands for Last Universal Common Ancestor, the original form of cellular life. This may, or may not be, the same as the origin of life itself, because that’s a matter of how life is defined. Whether it can be defined with or without a cell structure is just one point of contention. That there is such a thing as a LUCA – a starting point of life within a cell that is the progenitor of all cells we find today, has seemed to be the trend of evidence but remains under dispute. (Dispute here refers to opinions, theories, and hypotheses held by biologists, paleobiologists, biochemists, and other scientists and not the eternal disputations of religious proxies such as Intelligent Design believers.)

Chemiosmosis, also not a familiar word, is at the heart of this paper’s story on the origin of life. Molecular energy, in the form of hydrogen ions (charged protons, both positive and negative), has greater potential energy when one area has more ions than another. The difference between one concentration of ions and another is a proton gradient; and gradients can be increased by separating concentrations of ions with a membrane (in this case, a cell wall). In all living cells, the area outside cell walls has a higher concentration of ions, than within the cell. This relatively high gradient can drive the ions from the high concentration to move toward the area of low concentration. Cell membranes have developed so that selectively ions are allowed through the membrane. As they pass, their potential energy is converted into chemical energy for a key metabolic reaction – the creation of Adenosine Triphosphate (ATP), a universal form of stored energy used by living organisms. This process of allowing ions to pass through a cell membrane to power the creation of ATP is chemiosmosis. (Think chemical osmosis.)

What this paper says is that without chemiosmosis, there is no energy for life. Chemiosmosis does not take place in a soup (technically, a free mixture of organic compounds) because any ions that are present will be more or less evenly distributed throughout the soup. No proton gradient, no energy. So what, during the time at the origin of life, could provide a gradient that would suggest the formation of cell membranes?

Perhaps primordial soup should be replaced with the primordial vent. The paper makes an almost astonishing but plausible leap: Life began in the microscopic cavities found in the lava of hydrothermal vents. This was based on research done by geochemist Michael J. Russell, which showed that a proton gradient exists in these tiny, rocky, ‘cells’ near the volcanic vents in today’s ocean deep. The conclusion drawn is that the organic compounds for life were abundant around the chemically rich volcanic vents, and the micro-cavities provided the cell-like environment – complete with a kind of inorganic chemiosmosis – as a template for the later development of biological cell structure.

Here’s how one of the study’s authors put it:

“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.

[Source: EurekAlert]

The scientists involved with this paper are well aware of its ‘revolutionary’ nature. They don’t seem to shy away from mentioning that the rest of the biology community has ‘primordial soup’ stuck in their heads. So they will not be surprised if their assertions are…picked apart, attacked, challenged, debated. It will be the usual scientific skepticism with perhaps more animus than usual. Fortunately, it seems like their hypothesis can be researched. There are real undersea volcanic vents to explore. The conditions of lava cavities in these vents should be duplicable in the laboratory. There are experts in all aspects of this broad assertion. At the very least it suggests avenues of research that have yet to be taken.

Unless there are some glaring technical or factual errors to destroy the credibility of this original paper, look forward to years of follow-up. It’s science at its most fundamental.