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Science Square (Issue 109)
Jan 1, 2016

Potentially habitable Earth-like planet discovered

Wright DJ et al. Three planets orbiting Wolf 1061. Astrophysical Journal Letters, December 2015.

Astronomers from Australia have discovered the closest potentially habitable planet outside our solar system. They named it Wolf 1061c. It is four times the mass of Earth and only 14 light years away (126 trillion kilometers). The closest exoplanet discovered so far was Gliese 667c, which is 22 light years from earth. Wolf 1061c is located in the constellation Ophiucus and is one of three planets that orbit around a red dwarf star, Wolf 1061. Scientists find this discovery particularly exciting, because all three planets have low enough mass to have potentially solid rocky surfaces, unlike gaseous planets, such as Neptune. The one orbiting closest to Wolf 1061 would be too hot and the furthest one would be too cold. But the one in the middle, Wolf 1061c, is potentially optimum for generating temperatures just right for the formation of liquid water and, ultimately, life. Red dwarfs are known to be very active with X-ray bursts and super flares, which doom the possibility of any life. However, Wolf 1061 seems to be a quiet star, and very similar to our sun. The next challenge for scientists is to develop a method to study the atmosphere of Wolf 1061c to conclusively say whether it is conducive to life.

Most cancers are found to be avoidable

Wu S. et al. Substantial contribution of extrinsic risk factors to cancer development. Nature, December 2015.

It has been long recognized that cancer is caused by a mix of factors, including genes, lifestyle, and environment. However, the relative contributions of each factors have never been settled. A recent study found that the risk of developing most cancers is more correlated to lifestyle and environmental factors than genes and DNA mutations. The biggest risk factors are diet, sun exposure, UV radiation, tobacco, alcohol, the human papilloma virus, and hepatitis B and C. They make up between 70% and 90% of several types of cancer, including lung, colorectal, skin, and cervical. Researchers particularly focused on people who move from a low-risk cancer area to a high-risk cancer area, and found that migrated people soon developed diseases at significant rates consistent with new risky environments. They also analyzed a comprehensive set of specific mutations associated with certain cancers. Ultraviolet light, for example, creates a signature of mutations in DNA. When cross-compared, spontaneous mutations during cell division rarely reaches the frequencies of producing cancer mutations, even in tissues with high rates of cell division. In almost all cases, the research team found that some exposure to environmental factors would be needed to trigger the disease. So if you smoke or are overweight or tan for hours under the sun, you dramatically increase your odds getting cancer. You can do a lot to reduce your cancer risk; you can't just blame "bad genes" for getting sick.

Mutant mosquitos to stop malaria

Gantz VM et al. Highly efficient Cas9-mediated gene drive for population modification of the malaria vector mosquito Anopheles stephensi. PNAS, December 2015.

The tiny mosquito is one of the deadliest weapons in human history. Malaria is thought to be the oldest and deadliest disease. Despite intense efforts at treatment and eradication, it still is a reason for the death of approximately half a million people per year. So researchers have changed their tactics and tried to treat mosquitos instead of humans. Researchers used the revolutionary gene-editing technique CRISPR-Cas9 and generated a new breed of malaria with two genetic modifications. The first modified gene released antibodies against the malarial parasite and rendered its host immune to the parasite. The second modified gene, called “the gene drive,” would copy and paste the malaria-resistant genes into another mosquito, when mated. This two-gene system has the potential to spread malaria resistance across a wild population in just 10 generations – in other words, a single summer. Experts think that further research is needed before conducting a field trial. One potential problem would be to create a “hole” in the eco-system by changing the balance of malaria-carrying mosquito species. However, since the approach does not kill mosquitos rather make them resistant to the parasites, only a small amount of ecological damages are expected.