Science Concentrates SEPARATIONS
▸ Sulfur dioxide exposure linked to lower sperm count In China, men’s sperm counts have plummeted by nearly 30% since 2001, a problem experienced worldwide. A new study conducted in the industrial city of Wuhan links that decrease to exposure to sulfur dioxide emitted from burning fossil fuels (Environ. Sci. Technol. 2017, DOI: 10.1021/ acs.est.7b03289). Yuewei Liu of Hubei Provincial Center for Disease Control & Prevention and his team analyzed semen samples collected from 1,759 men who had visited Tongji Hospital between 2013 and
A study done in Wuhan, China, shows that sulfur dioxide exposure may contribute to worsening semen quality. 2015 seeking help to conceive a child with their partners. The researchers measured sperm concentration, total sperm, and total motile sperm in each sample, controlling for factors that might affect semen quality, such as age and smoking. The scientists then estimated the men’s exposure to air pollutants for the 90 days prior to semen collection using data from nine air-quality monitoring stations in Wuhan. Liu says that for each 10 µg/m3 increase in SO2 exposure during the first stage of sperm development, sperm concentration dropped by 6.5%, total sperm count by 11.3%, and total motile sperm by 13.2%.—JANET PELLEY,
special to C&EN
CANCER
▸ Nerve signaling encourages tumor growth Nerves inside prostate tumors release chemical compounds that stimulate the
6
C&EN | CEN.ACS.ORG | OCTOBER 30, 2017
Surface diffraction separates isotopes Isotope separation methods are key As a beam of neon isotopes (red and blue) strikes a silicon crystal to numerous scientific and industrial (green), surface diffraction processes. Nuclear power plants and causes a portion of the beam weapons, for example, require fuels to separate into isotopically enriched in a select isotope. And isoenriched streams. topically pure or enriched samples are used in scientific research and medical procedures. Isotopes can be separated via fractional distillation, gaseous diffusion, and centrifugation. The process can also be driven by chemical, magnetic, and electrostatic methods. But these techniques are often energy intensive and require many sequential separation steps. Kevin J. Nihill, Jacob D. Graham, and Steven J. Sibener of the University of Chicago have come up with a potentially simpler method based on surface diffraction. The team reports that when a beam of neon strikes a methyl-capped silicon crystal, a portion of the beam diffracts, scattering 20Ne and 22Ne isotopes into beams that emerge at slightly different angles (Phys. Rev. Lett. 2017, DOI: 10.1103/PhysRevLett.119.176001). A single pass causes 22Ne, the less abundant isotope, to be enriched by a factor of 3.5. A higher degree of separation can be achieved by using additional diffraction steps or by exploiting mass-based differences in the isotopes’ velocities, the team suggests.—MITCH JACOBY
These specific nerves send signals by releasing the neurotransmitter noradrenaline, which binds Neuron to the β2-adrenergic receptor (ADRβ2). In the new study, the researchers determined that Noradrenaline ADRβ2 noradrenaline activates ADRβ2 in Endothelial cell the endothelial cells of the mice’s Nucleus blood vessels. Once activated, ADRβ2 promotes the formation Noradrenaline released Glycolysis by nerve cells promotes of new blood vessels—a process xidati Oxidative angiogenesis by activating called angiogenesis—by ensuring phhory phosphorylation ADRβ2 on blood vessel the cells continue to metabolize endothelial cells, which glucose through glycolysis. When in turn ensures the cells the researchers knocked out the metabolize glucose through gene for ADRβ2 in the endothelial glycolysis. cells, the cells used an alternative growth of blood metabolic pathway called oxidavessels feeding tive phosphorylation, and as a result, there the cancer cells, according to a study in was little blood vessel growth. Frenette mice (Science 2017, DOI: 10.1126/science. points out that some anticancer therapies aah5072). Therapies that block this type targeting angiogenesis have not had longof chemical signaling could help slow the term success against prostate tumors. He growth of tumors, the researchers say. In proposes studying the effectiveness of 2013, Paul S. Frenette of Albert Einstein targeting angiogenesis along with nerve College of Medicine and colleagues found signaling with β-blockers, which inhibit that destroying nerves in tumors halted the progression of prostate cancer in mice. ADRβ2.—MICHAEL TORRICE
Tumor
C R E D I T: A PS /A LA N STO N EB RA KE R ( MO LECU LA R BEA M ) ; BA R NA BY CH A M BE RS/ S H U T T E RSTO CK (W U H AN ); S CI E N CE (N E RV E CE L L )
POLLUTION
