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Archive - Aug 19, 2017

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New Findings Challenge Dogma of How Dopamine-Releasing Neurons Communicate

Researchers at the University of Pittsburgh (Pitt) have uncovered the mechanism by which neurons keep up with the demands of repeatedly sending signals to other neurons. The new findings, made in fruit flies and mice, challenge the existing dogma about how neurons that release the chemical signal dopamine communicate, and may have important implications for many dopamine-related diseases, including schizophrenia, Parkinson's disease, and addiction. The research conducted at Pitt and Columbia University was published online on August 17, 2017 in Neuron. The article is titled “Neuronal Depolarization Drives Increased Dopamine Synaptic Vesicle Loading via VGLUT.” Neurons communicate with one another by releasing chemicals called neurotransmitters, such as dopamine and glutamate, into the small space between two neurons that is known as a synapse. Inside neurons, neurotransmitters awaiting release are housed in small sacs called synaptic vesicles. "Our findings demonstrate, for the first time, that neurons can change how much dopamine they release as a function of their overall activity. When this mechanism doesn't work properly, it could lead to profound effects on health," explained the study's senior author Zachary Freyberg, MD, PhD, who recently joined Pitt as an Assistant Professor of Psychiatry and Cell Biology. Dr. Freyberg initiated the research while at Columbia University. When the researchers triggered the dopamine neurons to fire, the neurons' vesicles began to release dopamine as expected. But then the team noticed something surprising: additional content was loaded into the vesicles before they had the opportunity to empty. Subsequent experiments showed that this activity-induced vesicle loading was due to an increase in acidity levels inside the vesicles.

New Bio-Optical Imaging Technique Is Fast and Economical

A new approach to optical imaging makes it possible to quickly and economically monitor multiple molecular interactions in a large area of living tissue -- such as an organ or a small animal; technology that could have applications in medical diagnosis, guided surgery, or pre-clinical drug testing. The method, which was published online on June 5, 2017 in Nature Photonics, is capable of simultaneously tracking 16 colors of spatially linked information over an area spanning several centimeters, and can capture interactions that occur in mere billionths of a second. The article is titled “Compressive Hyperspectral Time-Resolved Wide-Field Fluorescence Lifetime Imaging.” "We have developed a smart way to acquire a massive amount of information in a short period of time," said Dr. Xavier Intes, a Professor of Biomedical Engineering at Rensselaer Polytechnic Institute. "Our approach is faster and less expensive than existing technology without any compromise in the precision of the data we acquire." As its name implies, optical imaging uses light to investigate a target. In biomedical applications, optical imaging has many advantages over techniques such as MRI and PET, which use magnetism and positron emissions to acquire images inside of living tissue. The method the Intes lab developed makes use of advanced optical imaging techniques -- fluorescence lifetime imaging, paired with foster resonance energy transfer -- to reveal the molecular state of tissues. In fluorescence lifetime imaging (FLIM), molecules of interest are tagged with fluorescent "reporter" molecules which, when excited by a beam of light, emit a light signal with a certain color over time that is indicative of their immediate environment. Reporter molecules can be tuned to offer information on environmental factors such as viscosity, pH, or the presence of oxygen.

Invitation to ASEMV 2017 Annual Meeting (Exosomes & Microvesicles) in Asilomar, California (October 8-12)

The American Society for Exosomes and Microvesicles (ASEMV) is inviting interested scientists to the ASEMV 2017 meeting, to be held October 8-12, 2017 at the Asilomar Conference Center in California. This center is located on the Monterrey peninsula, just south of San Francisco (www.visitasilomar.com). The meeting will cover the full breadth of the exosome field, from basic cell biology to clinical applications, and follow the ASEMV tradition of inclusion and diversity as participants learn about the latest advances in the field. ASEMV 2017 is a forum for learning the latest discoveries in the field of exosomes, microvesicles, and extracellular RNAs. Over the course of four days at the Asilomar Conference Center, ASEMV 2017 will offer presentations from leading scientists and young researchers. Topics will span the breadth of the extracellular vesicle/RNA field, including the basic sciences, disease research, translation efforts, and clinical applications. Talks will be presented in multiple sessions, beginning at 7 pm on Sunday, October 8, 2017, and concluding at 4 pm on Thursday, October 12, 2017. Poster sessions will run throughout the meeting, with ample time to get to know your colleagues in the field and explore the many opportunities in this rapidly expanding field. Please see the links below.

Scientists Identify & Characterize Over 20 Odorant/Pherome Receptors in Ants

Queen ants spend most of their time having babies. To reign supreme in a colony, the queens exude a special scent, or pheromone, on the waxy surface of their body that suppresses ovary development in their sisters, rendering the latter reproductively inactive workers that find food, nurse the young, and protect the colony. Now, researchers at the University of California, Riverside (UCR) have begun to unravel the molecular mechanisms underlying how ants sense these pheromones and how they control reproduction regulation and other social activities in ant communities. The research, published on August 17, 2017 in Nature Communications, highlights how ants use olfactory receptors to distinguish between colony members so they can work together in a complex, hierarchical society. The open-access article is titled “Specialized Odorant Receptors in Social Insects That Detect Cuticular Hydrocarbon Cues and Candidate Pheromones.” The findings could help in the development of new pest management strategies. The research team, led by Dr. Anandasankar Ray, an Associate Professor in the Department of Molecular Cell Systems Biology at UCR, has identified and characterized more than 20 receptors found on the antennae of worker ants that play a role in the division of labor within colonies. Among these receptors is one that responds specifically to a pheromone produced by queen ants, an interaction that ultimately results in a physiological change to workers' ovaries. Ants are eusocial insects, meaning they live in cooperative groups where one female and several males are involved in reproduction, and non-breeding individuals play specialized roles, such as caring for the young, finding food, and warding off enemies.

H. pylori Bacteria Send Stomach Stem Cells into Overdrive; May Be Mechanism Underlying H. pylori-Caused Gastric Carcinoma

Gastric carcinoma is one of the most common causes of cancer-related deaths, primarily because most patients present at an advanced stage of the disease. The main cause of this cancer is the bacterium Helicobacter pylori, which chronically infects about half of all humans. However, unlike tumor viruses, bacteria do not deposit transforming genes in their host cells and how bacteria are able to cause cancer has so far remained a mystery. An interdisciplinary research team at the Max Planck Institute in Berlin, in collaboration with researchers at the Standord University School of Medicine, has now discovered that the bacterium sends stem cell renewal in the stomach into overdrive - and stem cell turnover has been suspected by many scientists to play a role in the development of cancer. By showing that the stomach contains two different stem cell types, which respond differently to the same driver signal, the scientists have uncovered a new mechanism of tissue plasticity. It allows tuning tissue renewal in response to bacterial infection. While it has long been recognized that certain viruses can cause cancer by inserting oncogenes into the host cell DNA, the fact that some bacteria can also cause cancer has been slower to emerge and much harder to prove. While it is now clear that most cases of stomach cancer are linked to chronic infections with H. pylori, the mechanism remains unknown. Dr. Thomas F. Meyer and his colleagues at the Max Planck Institute for Infection Biology in Berlin have spent many years investigating this bacterium and the changes it induces in the cells of the stomach epithelium. In particular, they were puzzled as to how malignancy could be induced in an environment in which cells are rapidly replaced.