2015 Nobel Prizes!

The 2015 Nobel Prizes were recently awarded.  Annual Nobel Prizes are awarded for achievement in Physics, Chemistry, Physiology/Medicine, Economics, Literature, and Peace.

Physics

The Nobel Prize in Physics was awarded to Takaaki Tajita and Arthur B. McDonald “for the discovery of neutrino oscillations, which shows that neutrinos have mass." The two researchers independently determined in 1998 and 2001, respectively, that neutrinos can switch between two identities, which required neutrinos to contain mass. This conflicts with the long-held Standard Model of Particle Physics, which describes all of the known particles and forces that make up the universe.

Figure 1: Neutrons can oscillate between the electron, tau, and muon form.

As the second most common particle in the universe (next to photons), trillions of neutrinos are continuously flying through the air… and ourselves. They travel almost as fast as light and have minimal interaction with matter. Only one-third of the amount of neutrinos calculated to be created from the sun were able to be detected, suggesting some unknown property of neutrinos that makes them hidden. There are three types of neutrons, and the sun emits only one kind. Separate experiments by Dr. Tajita and Dr. McDonald confirmed that neutrinos must undergo switching between the three forms, which due to quantum physics must involve neutrinos having mass. This work has opened up an entire field of research in the world of neutrinos, in addition to forcing physicists to re-evaluate the Standard Model.

A more technical and detailed overview of the discovery can be found here.

Physiology/Medicine

The Nobel Prize in Physiology or Medicine was awarded to the trio of William C. Campbell, Satoshi Omura and Youyou Tu. The award was divided, with half given to Drs. Campbell and Omura "for their discoveries concerning a novel therapy against infections caused by roundworm parasites" and the other half to Youyou Tu "for her discoveries concerning a novel therapy against Malaria."

Figure 2: Common parasitic diseases, with geographic areas of major incidence shown in blue.

The parasitic worms known as helminths are estimated to affect up to one third of the world’s population, causing a multitude of diseases in tropical locales. Two of these diseases are river blindness, which involves loss of sight due to corneal inflammation, and lymphatic filariasis (elephant man disease), which causes permanently debilitating swelling throughout the body. Dr. Campbell identified compounds in strains of the bacterium Streptomyces isolated by Dr. Omura that demonstrated great effectiveness against parasites. This led to the creation of an entirely novel class of drugs for combating helminth infection that has become revolutionary, potentially leading to eradication of these diseases in the near future.

Malaria is another devastating tropical disease, in this case caused by the single-cell parasite Plasmodium and transmitted through mosquito bites. Older treatments, which were never greatly effective, had become even less useful, and malaria incidence began expanding during the second half of the 20^th Century. Dr. Tu explored a more conventionall source than bacteria for finding an improved treatment – traditional herbal medicine. With ancient literature as her guide, Dr. Tu was able to successfully extract the active component from the Artemisia annua plant that showed effectiveness against Plasmodium. This treatment kills the parasite at an early stage of development and is much more highly effective than previous drugs, reducing mortality by more than 20%.

More detailed information can be found here.

Chemistry

The Nobel Prize in Chemistry was awarded jointly to Tomas Lindahl, Paul Modrich and Aziz Sancar "for mechanistic studies of DNA repair." These researchers each discovered a different form of DNA repair that maintains the integrity of our genome in response to damage from both external and endogenous sources.

The discovery of DNA repair mechanisms began when Dr. Lindahl’s research beginning in the late 1960s determined that the decay rate of DNA is much too high for life to be able to exist without robust repair mechanisms. Lindahl discovered that the DNA base cytosine degrades over time, causing mispairing during DNA replication. Using bacteria, he identified the molecular processes of base excision repair, which identifies and removes damaged bases followed by excision of the remaining nucleotide and replacement with the correctly-pairing base.

Dr. Sancar began investigating DNA repair of UV (ultraviolet)-induced damage during his doctoral studies, identifying an important gene involved in repair of UVA damage. UV light causes inappropriate binding (dimer formation) between adjacent thymine bases, interfering with proper DNA base pairing. Sancar eventually successfully identified in bacteria all genes of the nucleotide excision repair process and later examined the equivalent mechanism in humans. Nucleotide excision repair removes a section of DNA surrounding the thymine dimers and subsequently adds new nucleotides to repair the missing region.

Dr. Modrich’s research built upon the work of Matthew Meselson, who discovered that bacteria can repair mismatched bases. Modrich had previously discovered that DNA is methylated in bacteria, and together with Meselson he determined that during mismatch repair DNA repair factors are able to identify the incorrect (new) strand based on its lack of methylation. Modrich went on to study mismatch repair in human systems, however in human repair it is unclear how the new strand is identified.

Figure 3: A diagram of DNA replication. DNA ploymerases add complementary nucleotides to single-stranded RNA during both normal DNA replication for cell divisions as well as during repair of damaged regions. 

The discovery of these DNA repair mechanisms provided invaluable knowledge into how our genomic integrity is maintained. They have since led to important insights into the causes and effects of mutations and DNA repair insufficiencies, including the development of cancer.

More detailed information can be found here.

Other Nobel Prizes

There are also non-science Nobel Prizes in Literature and Peace that were created by Alfred Nobel. Additionally, a prize in Economics was added later and is officially known as the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel.  The 2015 Nobel Prize in Literature was awarded to Svetlana Alexievich "for her polyphonic writings, a monument to suffering and courage in our time."

The Peace Prize was awarded to National Dialogue Quartet "for its decisive contribution to the building of a pluralistic democracy in Tunisia in the wake of the Jasmine Revolution of 2011." The National Dialogue Quartet is a group of four Tunisian organizations that helped to coordinate and maintain the institution of a democratic political system in their country following the 2011 Arab Spring. Unlike many Middle Eastern nations who failed to establish a peaceful democratic society following the Arab Spring, the  Quartet oversaw political cooperation between Islamist and secular groups in order to ensure a peaceful political revolution..

The Economics Prize was awarded to Angus Deaton "for his analysis of consumption, poverty, and welfare." Dr. Deaton’s award is for his cumulative contributions to both his field and economic policymaking. He helped develop a system to estimate demand for various goods, established a correlation between consumption of goods and income, and more recently he has worked to quantify living standards and poverty in developing nations.

A more technical description of Deaton’s work can be found here.