The Indian summer we were enjoying here in Bristol died pretty spectacularly this Monday as the city showed her new students what Bristolian weather is really all about. The cold night prior and the rain threatening to soak right through my coat were firm reminders that the Autumn term is here to stay. Whilst my new Biochemistry students get accustomed to pipettes, centrifuges and the Henderson-Hasselbalch equation, scientists at the other end of the experience spectrum are this week acknowledged for their contribution to scientific progress and understanding. Here’s my round-up of 2014’s new Nobel Laureates.
All images are from official Nobel Prize information unless otherwise stated.
Physiology or Medicine – Your place in the world
What turns an unfamiliar place into a familiar one? If you move to a brand new city, how does your brain turn a bewildering array of streets and alleys into a domain you can navigate and shortcut with ease? Discovering some crucial brain cells that turn the real world outside into a virtual map inside our heads has earned John O’Keefe plus May-Britt and Edward Moser a Nobel Prize.
The work kicked off with John O’Keefe from UCL, London in the late 60s and early 70s. O’Keefe studied the brains of rats that were placed in a new environment and allowed to freely explore. He found a new type of cell which activated only when the rat was in a particular location. Different cells would activate at different parts of the room, so together they could build up an internal map. He found that when these “place cells” activated, the rat was really getting to know its new location.
All maps require some sort of grid system for scale, and the brain’s inner map is no different. Norwegian scientists May-Britt and Edward Moser built on O’Keefe’s work and found a cell type with the most remarkable properties. Rather than activating at one particular place, these cells would activate at intervals across the room, forming a staggeringly regular hexagonal grid. These “grid cells” work together with the place cells to form a natural internal GPS.
While many of us naturally learn to navigate new places with time, this ability can be tragically lost in diseases like Alzheimer’s, leading to much fear and confusion in sufferers. This work is being used to help understand how the system works in humans, and how to delay or reverse the degradation.
Physics – Let there be (blue) light
A quarter of the world’s electricity consumption goes into lighting up the darkness, so it’s important we do it right. The incandescent bulb which illuminated the 20th Century is well on its way out as newer LED technology outshines and outclasses it. LEDs are now twenty times more efficient and live a hundred times longer than incandescent bulbs, without being too expensive or overheating. You can see their clean, distinctive glow in new car headlights, streetlamps and traffic lights more and more these days.
For decades after LEDs were invented, there was a severe limitation which prevented their use as light sources. It seemed impossible to create a blue LED. This matters more than simply extending a colour pallet; blue light is a vital component in the white light we need to see around us. The Nobel Laureates in Physics this year earned their prize by developing the material that produces the elusive blue glow.
When Akasaki, Amano and Nakamura chose gallium nitride as their substance of choice, it wasn’t considered the most promising option. It was very difficult to grow crystals of sufficient size and quality to be used meaningfully, but they were not deterred. After years of careful development and a degree of fortitude, their hard work paid off and around 1992 the first blue LED was revealed.
Once the LEDs were made, exciting applications could commence – lasers! The Nobel laureates used microscopic blue LEDs in their invention of the blue-light laser, which can pack in four times as much information as infrared varieties. This technology is used today in Blu-ray players and is the reason Blu-ray discs can contain longer films at higher quality than standard DVDs.
Chemistry – Seeing smaller than small
The insides of our cells are bustling, dynamic nano-verses we thought we’d never be able to see with light microscopes. They were simply too small, it was thought. Light microscopes have improved tremendously over the last couple of centuries, but due to the nature of light itself, a fundamental size limit loomed: 0.2 micrometres.
This is smaller than a millionth of a metre, but there’s plenty going on at that scale and beyond. The viruses that make us sick and the antibodies which help make us better both operate on the nano-scale, far tinier than the supposed 0.2 micrometre limit.
For Betzig, Hell and Moerner, this was a rule designed to be broken and dedicated much of their scientific career to getting around that pesky limit. Each of the Nobel Laureates has contributed in their own way, but all used a feature called fluorescence where shining light on a particular molecule can make it glow for a while.
Stefan Hell’s worked throughout the 1990s on the design of a technique called STED (stimulated emission depletion) microscopy, which works a little like a “nano-sized flashlight”, scanning across a sample in fine detail. The light which travels over the sample uses two different pulses of laser beams. One light pulse excites the molecules it hits, making them fluoresce or glow. Another beam will immediately quench it all except for a nanometre-sized hole in the middle, which is allowed to stay bright. This allows for much finer precision than if a fluorescing beam was used alone.
Eric Betzig and William Moerner independently developed the ground work of a different system called single-molecule microscopy. This utilised an amazing jellyfish protein called GFP (green fluorescent protein, which I’ve talked about in another post here) which can be made to glow on or off at will on an individual basis. The microscope is sensitive enough to be able to detect exactly where one glowing GFP is, but if too many are turned on at once, it’ll just report an unhelpful blur. By switching on different combinations of GFPs spaced far apart, measuring them carefully then compiling the light positions, a very high resolution image reveals itself.
The Nobel Prize winners of 2014 in Chemistry pushed the boundaries of light microscopy and showed that the long-standing limit to what it can see doesn’t really exist at all. Microscopy has evolved into nanoscopy, and the inner secrets of the cell still await.