Ghost imaging gets super-resolution microscopy into high gear
Researchers at the Chinese Academy of Sciences have found a way to increase the imaging speed in nanoscopy using a technique called ghost imaging via sparsity constraints (GISC). The combined processes produce nanometer resolution using far fewer imaging frames than traditional nanoscopy – an approach that could allow scientists to capture previously unmatched details of living cell activity. Based on stochastic optical reconstruction microscopy (STORM), the ghost imaging approach creates an image by matching a light pattern that interacts with the object with a reference pattern that does not. The team also used compressive imaging, a computational method that allows images to be reconstructed using fewer exposures because an algorithm fills in the missing information. To deploy the technique, the team used a random phase modulator to transform fluorescence from a sample into a random pattern, enabling individual pixels of a high-speed complementary metal oxide semiconductor (CMOS) camera to gather light intensity from the whole object within a single frame. The light intensity was then matched wit ha reference light pattern. To test the technique, the investigators imaged a 60-nanometer ring. The ghost imaging approach achieved resolution using 10 image frames, versus nearly 4,000 frames with conventional STORM techniques. “We achieved an ultrahigh emitter density of 143 μm-2 while maintaining the precision of single-molecule localization below 25 nm,” the authors wrote. “We show that by employing a high-density of phot-switchable fluorophores, GISC nanoscopy can reduce the number of sampling frames by one order of magnitude compared to previous super-resolution imaging methods based on single-molecule localization. GISC nanoscopy may therefore improve the time resolution of super-resolution imaging for the study of living cells and microscopic dynamic processes.” The study was published in the Dec. 20, 2019, online issue of Optica.
Enterovirus contributes to islet autoimmunity
The Environmental Determinants of Diabetes in the Young (TEDDY) study group, led by researchers from the University of South Florida, has demonstrated that prolonged enterovirus infections increased the risk of islet autoimmunity in children who were genetically at high risk of developing islet autoimmunity and type I diabetes (T1D), though repeated short-term infections did not. Previous studies have hinted at a connection between viral infection and autoimmunity to pancreatic islet cells, which precedes T1D. However, such associations have been hard to pin down, given the diversity and transient nature of viral infections. In their experiments, the team took repeated stool samples from children at increased T1D risk, and used them to analyze their viromes over time and link those viromes to islet autoimmunity and T1D. They showed that “prolonged enterovirus B rather than independent, short-duration enterovirus B infections may be involved in the development of islet autoimmunity, but not T1D, in some young children. Furthermore, we found that fewer early-life human mastadenovirus C infections, as well as CXADR rs6517774, independently correlated with islet autoimmunity.” Their work appeared in the Dec. 2, 2019, online issue of Nature Medicine.
Acetyl CoA and metabolic health
Researchers at Duke University have gained new insights into the links between overnutrition and mitochondrial health. The team tested the theory that overnutrition damages mitochondria because it leads to high cellular levels of the metabolite Acetyl CoA, which increases protein acetylation. However, the authors showed that mitochondrial function was essentially normal in a double knockout mouse model designed to have high levels of acetylated proteins. They hypothesized that the functionally important consequence of high acetylation levels was a change in redox potential that affected the redox state of the enzyme co-factor nicotine adenine dinucleotide (NAD), and the activity of enzymes that use that co-factor. The team reported its findings in the Dec. 5, 2019, issue of Cell Metabolism.