Of grav-waves, biomolecules & circadian rhythms

Scientists working on these areas were honoured with the Nobel this year

The 2017 Nobel for Physics was the least surprising of awards. Half went to Rainer Weiss. The other half was shared by Barry C Barish and Kip S Thorne. All three were pioneers of the LIGO-Virgo collaboration that first captured gravitational waves in September 2015.

The award presented a peculiar problem. The prize can’t be shared by more than three people and well over a thousand scientists from 20 countries had been important participants in the LIGO (Laser Interferometer Gravitational-Wave Observatory), designing apparatus, capturing and deciphering data.

Weiss designed the basic detector, a laser-based interferometer. Thorne helped scale up the concept and turn it into reality. Barish led the LIGO team. An interferometer has two L-shaped, vacuum tunnels. Mirrors are suspended at the corner and ends of the L. A laser beam is bounced between the mirrors. If the arm lengths are unvarying, the beams will cancel out at the corner. 

A gravitational wave will stretch one arm and compress the other. Then the light changes since the beams travel different distances and don’t cancel out. The LIGO’s huge laser interferometers are sensitive enough to measure little changes thousands of times smaller than an atomic nucleus. By using two or more centres, false signals can be cancelled out and better location data derived.

In September 2015, there were two LIGO observatories, both in the USA. Since then, Italy’s Virgo facility has become operational. India is building its own LIGO and Japan is also building a grav-wave observatory. 

The first capture in September 2015 came from a merger of two black holes. Subsequently, three more mergers have been observed. Most recently, after Virgo became operational, a neutron star collision-merger was observed. That generated huge data across the electromagnetic spectrum, too, with observatories collaborating to share x-ray, visual and electromagnetic data. 

The LIGO proved that Einstein was correct in the General Theory of Relativity when he surmised gravitational waves distort space. It also confirmed that gravitational waves travel at light speed and that heavy elements including gold and platinum are formed in neutron star collisions. This new technology has altered our view of the universe and could lead to many breakthroughs.

The Chemistry prize went to Jacques Dubochet (University of Lausanne, Switzerland), Joachim Frank (Columbia University, USA) and Richard Henderson (MRC Laboratory of Molecular Biology, Cambridge, UK) for “developing cryo-electron microscopy for high-resolution structure determination of biomolecules in solution”.

Observing biological processes and molecular machinery at the atomic level is hard. Consider freeze-framing of, say, footage of a Federer backhand sliced into microseconds to understand how he hits the ball. In order to understand bio-processes at the molecular level, scientists must do this with really tiny objects and track both very fast and very slow processes.

These three scientists developed a method of freezing biomolecules during action and observing the processes in sequential detail at the atomic level. The only tool that can be used to visualise things at the molecular scale is the electron microscope. 

Frank figured out innovative image processing methods in the 1970s and 1980s. He pioneered the merging of electron microscope pictures to create 3-D images. Henderson improved on Frank’s techniques to generate three-dimensional images using electron microscopes at the atomic level. Dubochet added a technique involving water being cooled very quickly to solidify around a biosample, thereby ensuring that the sample retained its shape even in vacuum. Those technologies now allow for photographs of proteins and even viruses.

The 2017 Nobel Prize in Physiology or Medicine was awarded jointly to Jeffrey C Hall, Michael Rosbash and Michael W Young for “their discoveries of molecular mechanisms controlling the circadian rhythm”. All life is governed by an internal biological clock that synchronises their activity to the natural cycle that arises from the Earth’s rotations and revolutions. We experience jet lag when that clock is out of kilter.

These three scientists managed to isolate the key genes that control the biological rhythms of living beings. They used the good old fruit fly, a default for bio experiments, as their model organism. One gene encodes a protein that accumulates at night and is slowly degraded during the day. That protein controls bio-rhythms. Two other key genes also encode proteins that help with this process.  

Hall and Rosbach were collaborators at Brandeis University while Young was at Rockefeller University when they discovered the so-called period gene. Hall and Rosbach discovered the PER protein, which is encoded by period. Young found a second key clock gene, “timeless” that produces a second key protein, “TIM” and showed how PER and TIM worked in unison. Young later found yet another clock gene, “doubletime”. The interaction of the proteins secreted by these genes helps us understand how this self-regulation works.