Bulletin No. 1, 2016

News in Brief 53 Detecting the Most Precise Measurement of Reactor Antineutrino Spectrum The Daya Bay Collaboration now provides the most precise model-independent measurement of total antineutrino flux. The data were gathered by analyzing more than 300,000 reactor antineutrinos collected over the course of 217 days. The most challenging part of this work was to accurately calibrate the energy response of the detectors. Through dedicated calibration and analysis effort, Daya Bay was able to measure the neutrino energy to an unprecedented precision, better than 1%, over a broad energy range of the reactor antineutrinos. The Hong Kong team, with Prof. Chu Ming-chung (1st right), Department of Physics, as the principal investigator, has designed and built subsystems for detector monitoring, background measurement and data acquisition of the Experiment. Daya Bay’s measurement of antineutrino flux—the total number of antineutrinos emitted across the entire energy range—indicates that the reactors are producing 6% fewer antineutrinos overall when compared to some of the model-based predictions. This result is consistent with past measurements. This observed deficit has been named the ‘Reactor Antineutrino Anomaly’. Study Implicates a Gene in Alzheimer’s Disease A joint research conducted by Prof. Chan Man-lok Andrew at the Faculty of Medicine and an international team of researchers from Spain, Germany and the US has uncovered a link between the tumour suppressor protein PTEN and Alzheimer’s disease, potentially leading to a new treatment for this devastating neurodegenerative disease. The findings reveal that PTEN exacerbates the pathological effects of beta-amyloid. The research was conduc ted using cultured neurons and particularly bred mice. The study has two main goals: to discover how PTEN is recruited to the synapses in Alzheimer’s disease, and to propose a strategy for preventing it. Professor Chan generated a mouse strain carrying a modified PTEN that cannot be recruited to the synapses. Following this direction, he hopes to find the way to protect neurons from the toxic effects of beta-amyloid, and hence preserve memory. Hidden Genetic Mechanism Discovered in Horseshoe Crabs A team of researchers led by Prof. Jerome Hui (4th right) at the School of Life Sciences has recently investigated the three genomes out of the four extant horseshoe crabs, including the two of the four that can be found in Hong Kong. They discovered that ‘Whole Genome Duplication’ (WGD), a rare situation of evolution that was believed to happen only in the vertebrate ancestors, occurred in all three investigated horseshoe crabs. The research results suggest that extant sexually reproducing invertebrates can also have WGD via unknown genetic regulation and mechanism, which contradicts the long held view that only vertebrates can do so. Professor Hui said, ‘In terms of evolutionary biology, we can now prove that the differences between invertebrates and vertebrates are not solely due to WGD.’