October 17, 2018

In August, scientists at the University of Texas Southwestern Medical Center in Dallas announced that a revolutionary gene-editing technique called CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat) had been used to cure an inherited muscle-wasting disease in dogs. The announcement raised hopes that an effective treatment for Duchenne muscular dystrophy, the most common fatal genetic condition in children, can soon be developed. In the coming decades, scientists hope that CRISPR can treat or prevent more human diseases caused by faulty genes.

Scientists can manipulate the CRISPR process to delete, alter, or replace a gene with great accuracy. Credit: © Yurchanka Siarhei, Shutterstock

Duchenne muscular dystrophy is the most common and most rapidly progressive of the childhood muscle diseases. The disease is named after French neurologist Guillaume-Benjamin-Amand Duchenne, a pioneer in the detection and treatment of nervous and muscular disorders. Duchenne muscular dystrophy is caused by a mutation that disrupts the normal function of a gene involved in the development of muscle structure and function. Scientists have identified the genes that cause the disease, and they also have discovered a protein called dystrophin whose absence in muscle tissues causes the disease. Scientists have long held that gene therapy, where normal-functioning genes are introduced into the muscles, could increase production of dystrophin and effectively treat or even cure Duchenne dystrophy. However, gene therapy has had limited success thus far, mainly because of the extreme difficulty of cutting and repairing the precise sequence of DNA that causes the disease. CRISPR makes the cutting and repairing much easier.

In development since 2012, CRISPR is derived from a process that scientists first observed in 1987 occurring naturally in bacteria. In this process, bacteria forms its own sort of immune system. If a bacterium is infected by a virus, it grabs a bit of the viral DNA and keeps it as a reminder. If the bacterium encounters that viral DNA again, certain proteins are directed to slice it up, destroying the viral invader. Scientists simulated this bacterial process with CRISPR, which uses one of these slicing proteins, designated Cas9, to break DNA at specific locations. Scientists can manipulate this CRISPR-Cas9 process to delete, alter, or replace a gene with great accuracy.

The CRISPR-Cas9 process was first used to eradicate relatively harmless viruses in dogs before turning the process on the nonfunctioning dystrophin gene that causes muscular dystrophy. The CRISPR-Cas9 protein zeroed in on the unique DNA sequence of the faulty gene and sliced it away. The breaks created in the DNA molecule triggered the cell’s natural repair machinery, which rebuilt the DNA molecule to form a properly functioning gene and cured the dogs of muscular dystrophy.

Despite the potential benefits of this technology, experts in scientific ethics are debating how CRISPR-Cas9 and other advanced gene-editing techniques should be used in people. Current gene therapy using CRISPR focuses on somatic gene editing. In this process, the changes to DNA are made in somatic (body) cells that cannot not be passed on to the next generation. Body cells differ from germline cells (also called sex cells), which can alter human embryos and be passed down to future generations. Mistakes in the germline cell gene-editing process could inadvertently cause other health problems or even unknown diseases. These new problems could then be passed down through families.

Most countries have regulations that limit or prohibit experiments with gene-editing techniques involving humans. The United States National Institutes of Health prohibit laboratories that receive federal funds from experimenting with human embryos. In addition, the U.S. Food and Drug Administration is prohibited from evaluating any treatments that involve genetically modified human embryos. However, privately funded lab research has no such regulation. In addition, government regulations in such countries as China and the United Kingdom have recently permitted limited experiments with CRISPR involving human embryos.

October 5, 2018

Every year in the first week of October, the Nobel Foundation in Sweden awards Nobel Prizes to artists, economists, scientists, and peace workers who–in keeping with the vision of chemist and industrialist Alfred Nobel–have conferred the greatest benefit to humankind. On Monday, the foundation awarded the 2018 Nobel Prize in Physiology or Medicine jointly to scientists James P. Allison of the United States and Tasuku Honjo of Japan for their research on immunotherapy that stimulates the body’s immune system to recognize and attack cancer cells. Allison and Honjo helped develop powerful new therapies to treat, and in some instances cure, certain types of cancer.

Nobel Prize medal (Credit: Nobel Foundation)

James P. Allison is with the department of immunology at MD Anderson Cancer Center in Houston, Texas. Tasuku Honjo is a professor in the department of immunology and genomic medicine at Kyoto University.

On Tuesday, the Nobel Foundation announced the prize for physics had been awarded to three scientists: Arthur Ashkin (from the United States), Gérard Mourou (France), and Donna Strickland (Canada) for their groundbreaking inventions in the field of laser physics. Ashkin invented “optical tweezers,” an instrument that uses lasers to manipulate such tiny objects as atoms, viruses, and living cells. Mourou and Strickland worked together to generate the shortest and most intense laser pulses ever created. This technology has many useful applications and is the basis for LASIK eye surgery. The pair published an article on the laser research in 1985, when Mourou was teaching at the University of Rochester in New York and Strickland was a graduate student there.

Arthur Ashkin’s prize-winning work was conducted while he worked at Bell Laboratories in Holmdel, New Jersey. At age 96, he is the oldest Nobel Prize recipient ever. Gérard Mourou is currently with the École Polytechnique in Palaiseau, France. Donna Strickland is associate professor of physics and astronomy at the University of Waterloo in Canada. Strickland is just the third woman in 117 years to win the Nobel Prize in physics. Polish-born scientist Marie Curie shared the prize in 1903 for her research on radiation. In 1963, German-born scientist Maria Goeppert Mayer shared the prize for her research on atomic nuclei.

On Wednesday, Oct. 3, 2018, the Nobel Foundation announced that Americans Frances H. Arnold and George P. Smith would share the prize for chemistry with Sir Gregory Winter of the United Kingdom for using directed evolution to synthesize proteins. This process mimics natural selection, the driving force of biological evolution, in a laboratory to create novel proteins with useful properties.

Arnold is currently a professor at the California Institute of Technology (Caltech) in Pasadena. She is the fifth woman to win the chemistry prize. Smith is a former professor at the University of Missouri in Columbia. Winter is affiliated with the MRC Laboratory of Molecular Biology in Cambridge, England.

March 10, 2017

Hard gunk stuck in the teeth of fossil Neandertal jaws shows that the prehistoric human beings had a widely varied diet and a sophisticated knowledge of medicinal plants. Scientists analyzing dental calculus (a hard, yellowish substance formed by the buildup of plaque between teeth) from three Neandertal fossils found dramatic differences in diet and evidence that Neandertals likely used some foods as medicine. The scientists’ findings were published in the March 8 issue of the journal Nature.

The teeth of this fossilized Neandertal jaw revealed traces of poplar bark, a source of aspirin. The individual had also consumed Penicillium mold, source of the natural antibiotic penicillin. Credit: © Paleoanthropology Group MNCN-CSIC

Neandertals were prehistoric human beings who lived in Europe and central Asia from about 150,000 to 39,000 years ago. They looked quite different from modern humans. Neandertal skulls were huge compared to ours, with a projecting face; no chin; a low, sloping forehead; and a thick browridge (raised strip of bone across the lower forehead). Because Neandertals had such a brutish appearance, people long assumed the these prehistoric humans possessed only a crude and simple culture. However, new evidence shows they were perhaps smarter than we previously thought.

An international team of scientists examined three fossil Neandertal skulls dating from 42,000 to 50,000 years ago. Two of the skulls were from El Sidrón, a cave in Spain, and one was from Spy Cave in Belgium. The teeth of these fossils were coated with thick layers of hardened dental calculus. The scientists knew that this material preserves DNA from microbes and food debris that pass through an individual’s mouth during their lifetime. The dental calculus of the Spy Neandertal contained traces of meat from wooly rhinoceros and wild sheep, while evidence of plant foods was largely absent. In contrast, the two Spanish Neandertal fossils appeared to have survived on a vegetarian diet of edible moss, mushrooms, tree bark, and pine nuts.

Neandertals lived in Europe and Central Asia from about 150,000 to 39,000 years ago. Credit: © Jay H. Matternes

Other evidence showed that the El Sidrón Neandertals probably also used plants for medicine. The scientists recovered DNA from poplar trees in the dental calculus. While not eaten for food, these trees contain salicylic acid, the pain-relieving ingredient in aspirin. Preserved spores of the Penicillium mold, from which the life-saving antibiotic penicillin is produced, were also recovered. The scientists think the Neandertals ate the plant sources for their medicinal properties. One fossil skull showed evidence of a painful tooth infection, and DNA from a microbe known to cause stomach problems was also recovered from the calculus. Aspirin and penicillin would have helped.

Neandertals died out about 39,000 years ago, when physically modern human beings migrated into Europe. However, Neandertals did not disappear completely. Genetic evidence shows at least some Neandertals interbred with modern-looking populations that settled Europe, Asia, and the Pacific Islands. Neandertals are extinct, but they remain part of the ancestry of some modern peoples today.