It is heady territory for a postgraduate student: making sense of the origins of life itself. And the key to it all, explains Chris Lepper, holding it up for inspection, is this beige-coloured ceramic tube. Theoretically, inside its three-millimetre bore, the NMR specimen tube can contain 250 times atmospheric pressure, the equivalent of burying the tube’s contents deep within Earth’s mantle, which is more than enough for what Lepper wants to do.
The ceramic tube used to hold highly pressurised NMR samples.
His interest, and that of his PhD supervisors, Professor Geoff Jameson, Associate Professor Bill Williams and Dr Pat Edwards, is in how the molecules crucial to life’s origins behave at the lesser pressures found in the ocean deeps.
What do we know about how life began? Earth itself is known to be about 4.5 billion years old, and the earliest evidence of life comes in the form of fossilised mats of cyanobacteria called stromatolites in Australia that are about 3.4 billion years old. But these cyanobacteria are biologically complex; the consensus is that life began much earlier, perhaps around 3.8 billion years ago, and that the crucial molecule in the construction kit – the one Professor Jameson terms the ‘cantilever’ – was DNA’s near relative RNA.
As for where life began, one of the best candidates is in the deep sea around the hot, mineral-rich waters spewing from hydrothermal vents. Here can be found the sort of primordial stew of sulphur, carbon dioxide, hydrogen and trace metals in which simple organic molecules could form. But that notion is not without its difficulties, says Edwards.
A black smoker at a mid-ocean ridge hydrothermal vent.
“A lot of people liked the idea that the origin of life was at the bottom of the sea by these black smokers, but then people said, ‘Well it’s too hot down there, things will tend to fall apart’. But we haven’t looked at whether pressure might compensate by conferring some stability.”
This, then, is the basis of Lepper’s project: first to look at how the individual bases that make up RNA and DNA behave under conditions of extreme pressure and temperature; then to do the same thing with short sequences of bases; and finally to test RNA itself. Whatever the outcome, the result will be scientifically significant, but Edwards is in no doubt about the one that would create the most excitement.
“The great thing would be if we found that the pressure conferred greater stability, in which case it would lend credence to the idea that the origin of life was indeed at the bottom of the ocean near these black smokers.”
The next in line after Lepper for the use of the high-pressure NMR apparatus is Dr Jason Hindmarsh, who plans to investigate the use of pressure in food sterilisation. To date, most of the work that has been done on the effectiveness of pressure sterilisation has been relatively crude: subject samples of bacteria to varying conditions of pressure and temperature and only afterwards determine whether or not they have died. Using the high-pressure NMR, Hindmarsh believes he can short-cut this, identifying the exact moment and the precise conditions under which the bacterial cell membranes begin to break down and cell death occurs.
A rendering of a cloverleaf RNA motif derived using an NMR spectrometer.
