Major Developments Major Developments by Calendar Year

The Nobel Prize in Medicine, 2007 was awarded to Mario R. Capecchi, Sir Martin J. Evans and Oliver Smithies (in the words of the Academy) “for their discoveries of principles for introducing specific gene modifications in mice by the use of embryonic stem cells.” They have made a series of ground-breaking discoveries that led to the creation of an immensely powerful technology referred to as gene targeting in mice. Gene targeting is often used to inactivate single genes, a process known as “gene knockout.” These experiments have helped us understand the roles of numerous genes in embryonic development, adult physiology, aging, and disease. With gene targeting it is possible to produce any type of DNA modification in the mouse genome. Gene targeting has already produced more than five hundred different mouse models of human disorder, which include cardiovascular and neuro-degenerative diseases, diabetes, and cancer. Information about the function of our bodies through out life is carried within the DNA, which is packaged in chromosomes, which occur in pairs- one from the father and one from the mother. Exchange of DNA sequences occur by a process called homologous recombination. Capecchi demonstrated that homologous recombination was possible between introduced DNA and the chromosomes with the mammalian cells. In this manner, defective genes could be repaired by homologous recombination with the incoming DNA. In his attempts, Smithies had discovered that endogenous genes could be targeted irrespective of their activity.

Martin Evans had worked with embryonal carcinoma (EC) cells, which could give rise to almost any cell type. Evans discovered that chromosomal normal cell cultures could be established directly from early mouse embryos, now referred to as embryonic stem cells (ES) cells. The reports which showed the homologous recombination in ES cells used to generate gene-targeted mice were publicized in 1989. Since then, gene targeting has developed into a versatile technology. We can now introduce mutations that can be activated at specific time points, or in specific cells or in organs, both during the development and the adult animal.

Mario R. Capecchi, US citizen, PhD in Biophysics, Harvard University. Presently Howard Hughes Medical Institute Investigator and Distinguished Professor of Human Genetics and Biology at the University of Utah, Salt Lake City, UT , USA.

Sir Martin J. Evans, British citizen, PhD in Anatomy and Embryology, University College, London UK. He is a Director of the School of Biosciences and professor of Mammalian Genetics, Cardiff University, UK.

Oliver Smithies, US citizen, PhD in Biochemistry 1951, Oxford University, UK. He is a Excellence Professor of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, NC, USA.

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The Nobel Prize in Chemistry, 2007 was awarded to Gerhard Ertl, for his entire work that laid the foundations for modern surface chemistry. He had spent the most part of his life studying reactions on surfaces.

Surface chemistry is a very common phenomenon in the industrial and even everyday processes. From producing nitrogen to the destruction of ozone layer each process has a key step where in a deep understanding of the physical and chemical processes underlying the overall reaction plays a vital role in obtaining a higher yield of the product.

Prof Ertl’s work with the Haber-Bosch process was the highlight of the Nobel prize achievement. The process is used to create ammonia from nitrogen and hydrogen in the presence of iron. Though the discovery of the process spawned Nobel prizes for both Haber(1918) and Bosch(1931), the reaction mechanism was unknown until Ertl’s work. To study the reaction mechanisms Ertl made use of a number of techniques, such as generating idealized iron surfaces, introducing precise amounts of gas at low pressure, using a litany of spectroscopic techniques that probed molecules at the surface, and also studying the reverse reaction of the process using heavy hydrogen as a tracer molecule. Prof Ertl discovered that the splitting of the triple bond in the Nitrogen molecule was the slowest step in the Haber-Bosch process. So, to speed up the production of ammonia, the nitrogen molecule cleavage had to be fastened.

Ertl’s work also included the detailed study of carbon monoxide being converted to carbon dioxide over platinum. This reaction – or the one that doesn’t use platinum- is the one that is used by catalytic converters in cars today to reduce the harmful emissions. The detailed and controlled methodology that Ertl used has given rise to modern surface chemistry and earned him the Nobel Prize.

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2007 jointly to Albert Fert of France and Peter Grunberg of Germany. It is been awarded for their discovery of an entirely new physical effect known as Giant Magnetoresistance or GMR in 1988. The two scientists had independently discovered the effect in the same year that led to far reaching applications in the field of electronics and nanotechnology.

GMR is a quantum mechanical magnetoresistance effect observed in thin films that are composed of alternating ferromagnetic and nonmagnetic layers. It manifests itself as a significant decrease (typically 10-80%) in electrical resistance in the presence of magnetic field. In the absence of an external magnetic field, the direction of magnetization of adjacent ferromagnetic layers is anti-parallel due to a weak anti-ferromagnetic coupling between the layers resulting in high-resistance magnetic scattering due to electron spin. On applying an external magnetic field, the magnetization of the adjacent ferromagnetic layers is parallel resulting in lower magnetic scattering and lower resistance.

A system of this kind is the perfect tool for reading data from hard disks when information that is coded magnetically should be converted into electric current. In 1997, the first read out head that was based on the GMR was launched and that became the standard technology. A hard disk stores information in the form of microscopic small areas magnetized in different directions. The information is retrieved by a read out head that scans the disk and registers the magnetic changes. If the hard disk is smaller and more compact then it would require a more sensitive read out head to read the information on the disk. A read out head can convert very minute magnetic changes into differences in electrical resistance resulting in changes in the current emitted by the read-out head. The current is the signal from the read out head representing the ones and zeros. GMR can also be considered as one of the first real applications of the promising and evolving field of nanotechnology.