The Nobel Prizes, 2012

D. Indumathi, The Institute of Mathematical Sciences, Chennai

The Royal Swedish Academy of Sciences has recently announced the Nobel prizes in Physics, Chemistry and Economics.  Nobel prizes are also awarded for Physiology and Medicine and Peace.

The Physics Prize
The Nobel Prize in Physics for 2012 goes to Serge Haroche, Collège de France and Ecole Normale Supérieure, Paris, France, and David J. Wineland, National Institute of Standards and Technology (NIST) and University of Colorado Boulder, CO, USA for ground-breaking experimental methods that enable measuring and manipulation of individual quantum systems.
Newton's laws help determine the path of a particle of definite mass, when a force acts on it. For instance, when you step on the accelerator of a car, you know that it will go faster, and when you brake, it will slow down.
However, when you consider elementary particles such as electrons in atons that are very very small, this so-called classical picture breaks down. The behaviour of such particles is immensely complicated and is controlled by what is called quantum mechanics. The mysterious thing about quantum systems is that, as soon as you choose to isolate a single particle from a system in order to study it, it loses its quantum nature!
Through their ingenious laboratory methods Haroche and Wineland together with their research groups have managed to measure and control very fragile quantum states, which were previously thought inaccessible for direct observation. The new methods allow them to examine, control and count the particles.
Their methods have many things in common. David Wineland traps electrically charged atoms, or ions, controlling and measuring them with light, or photons.
Serge Haroche takes the opposite approach: he controls and measures trapped photons, or particles of light, by sending atoms through a trap. 
Both Laureates work in the field caled quantum optics that studies the fundamental interaction between light and matter, a field which has seen considerable progress since the mid-1980s. Their ground-breaking methods have enabled this field of research to take the very first steps towards building a new type of super-fast computer based on quantum physics.
Perhaps the quantum computer will change our everyday lives in this century in the same radical way as the classical computer did in the last century. The research has also led to the construction of extremely precise clocks that could become the future basis for a new standard of time. The new clocks are more than hundred-fold greater precision than present-day caesium clocks.

The Chemistry Prize
The Nobel Prize in Chemistry for 2012 goes to Robert J. Lefkowitz, Howard Hughes Medical Institute and Duke University Medical Center, Durham, NC, USA, and Brian K. Kobilka, Stanford University School of Medicine, Stanford, CA, USA for studies of G-protein-coupled receptors.
Your body is a fine-tuned system of interactions between billions of cells. For a long time, it remained a mystery how cells could sense their environment. Scientists knew that hormones such as adrenalin had powerful effects: increasing blood pressure and making the heart beat faster. The adrenalin was administered to the outside of the cell, but this led to changes in its metabolism that they could measure inside the cell. Each cell has a wall: a membrane of fat molecules that separates it from its environment.
How did the signal get through the wall? How could the inside of the cell know what was happening on the outside? They suspected that cell surfaces contained some kind of recipient for hormones. But for a long time they did not know what these receptors actually consisted of and how they worked.
It turns out that each cell has tiny receptors that enable it to sense its environment, so it can adapt to new situations.  Lefkowitz used radioactive iodine in order to trace cells' receptors. The iodine attaches itself to various harmones and the radioactivity of the iodine gives a signal to tell where it is. This way he managed to find the receptor for adrenalin: it was hiding in the cell wall. He and his collaborators also found out how this receptor works.
The team achieved its next big step during the 1980s. They had newly hired Kobilka as part of the team. He accepted the challenge to isolate the gene that codes for the adrenalin receptor. The human genome has thousands of genes that determine various characteristics of a human being. The task of isolating just one gene from the gigantic human genome is really difficult and he used a creative approach.
When the researchers analyzed the gene, they discovered that the receptor was similar to one in the eye that captures light. They realized that there is a whole family of receptors that look alike and function in the same manner.
Today this family is referred to as G-protein-coupled receptors. About a thousand genes code for such receptors.
Furthermore, in 2011, Kobilka achieved another break-through; he and his research team  got an image of the receptor at the very moment when it transfers the signal from the hormone on the outside of the cell to the G-protein on the inside of the cell.
This image is a molecular masterpiece -- the result of decades of research. The figure shows the cell membrane or wall with an adrenalin receptor in it. A hormone (small dots near top of receptor) attaches to the receptor just outside the cell wall while a G-protein (darker riboons at the bottom) attaches itself on the inside.
The studies by Lefkowitz and Kobilka are crucial for understanding how G-protein-coupled receptors function. About half of all medications today achieve their effect through G-protein-coupled receptors.

The Medicine/Physiology Prize
The Nobel Assembly at Karolinska Institutet has awarded the Nobel Prize in Physiology or Medicine 2012 jointly to John B. Gurdon and Shinya Yamanaka for the discovery that mature cells can be reprogrammed to become pluripotent.
The Nobel announcement is hard to understand. Let us start with the nature of cells. We know that there are many different types of cells in our body. Skin cells, liver cells, blood cells, all have different functions. But all humans start out as a collection of a small number of cells, the embryo. These cells divide and so their numbers increase. Initially they are all identical. They are called immature cells. They are capable of developing into all the specialised kinds of cells that form the adult. Such cells are called pluripotent stem cells.
For example, as the embryo develops, these cells give rise to nerve cells, muscle cells, liver cells, etc., that carry out specific tasks in the adult body. This journey from immature to specialised cell was previously considered to be unidirectional. That is, after maturation it would no longer be possible for the cell to return to an immature, pluripotent stage.

BOX
Different kinds of stem cells
Stem cells are biological cells found in all multicellular organisms, that can divide and differentiate into different specialized cell types. They can also self-renew to produce more stem cells.
Totipotent (or omnipotent) stem cells can differentiate into embryonic and extraembryonic cell types. Such cells can construct a complete, viable organism. These cells are produced from the fusion of an egg and sperm cell.
Pluripotent stem cells are the descendants of totipotent cells and can differentiate into nearly all cells.
Multipotent stem cells can differentiate into a number of cells, but only those of a closely related family of cells.
Oligopotent stem cells can differentiate into only a few cells, such as lymphoid or myeloid stem cells.
Unipotent cells can produce only one cell type, their own, but have the property of self-renewal, which distinguishes them from non-stem cells (e.g., muscle stem cells).
END OF BOX

John B. Gurdon discovered through a remarkable experiment in 1962 that the specialisation of cells is actually reversible. His Science Report shown in the picture clearly does not match his abilities!
He replaced the immature cell nucleus in an egg cell of a frog with the nucleus from a mature cell from the intestine of a tadpole. This modified egg cell developed into a normal tadpole.  This means that the DNA of the mature cell still had all the information needed to develop all cells in the frog although it was now a specialised cell.
Gurdon's landmark discovery initiated intense research and the technique was further developed, leading eventually to the cloning of mammals.  But his experiment involved the removal of cell nuclei followed by their introduction into other cells. Would it ever be possible to turn an intact cell back into a pluripotent stem cell?
Shinya Yamanaka was able to answer this question more than 40 years later, in 2006. He showed how intact mature cells in mice could be reprogrammed to become immature stem cells. Surprisingly, by introducing only a few genes, he could reprogram mature cells to become pluripotent stem cells, i.e. immature cells that are able to develop into all types of cells in the body.
The resulting induced pluripotent stem cells could develop into different mature cell types such as fibroblasts, nerve cells and gut cells.
These groundbreaking discoveries have completely changed our view of cell development and cellular specialisation. We now understand that the mature cell does not have to be confined forever to its specialised state. Textbooks have been rewritten and new research fields have been established. By reprogramming human cells, scientists have created new opportunities to study diseases and develop methods for diagnosis and therapy.
For instance, skin cells can be obtained from patients with various diseases, reprogrammed, and examined in the laboratory to determine how they differ from cells of healthy individuals. Such cells constitute invaluable tools for understanding disease mechanisms and so provide new opportunities to develop medical therapies.

The Economics Prize
The Royal Swedish Academy of Sciences has awarded The Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel for 2012 to Alvin E. Roth, Harvard University, Cambridge, MA, USA, and Harvard Business School, Boston, MA, USA and Lloyd S. Shapley, University of California, Los Angeles, CA, USA "for the theory of stable allocations and the practice of market design".

-- Adapted from nobelprize.org