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Archive - Nov 29, 2015

Birds & Humans Share Exact Same Mechanism for Sound Production, Even Though Birds Do Not Have Larynx; Surprising Finding May Shed New Light on Neural Mechanisms Underlying Vocal Learning

Birds and humans look different, sound different, and evolved completely different organs for voice production. But now, new research published online on November 27, 2015 in an open-access article in Nature Communications reveals that humans and birds use the exact same physical mechanism to make their vocal cords move and thus produce sound. The article is titled “Universal Mechanisms of Sound Production and Control in Birds and Mammals.” "Science has known for over 60 years that this mechanism - called the myoelastic-aerodynamic theory, or in short the MEAD mechanism- drives speech and singing in humans. We have now shown that birds use the exact same mechanism to make vocalizations. MEAD might even turn out to be a widespread mechanism in all land-dwelling vertebrates", says lead author of the paper, Associate Professor Coen Elemans, Ph.D., Department of Biology, University of Southern Denmark. Co-authors of the new paper are from Emory University in the United States, Max Planck Institute for Ornithology in Germany, Palacky University in the Czech Republic, and additional collaborating institutions. Over the last year Dr. Elemans and his colleagues studied six different species of bird from five avian groups. The smallest species, the zebra finch, weighs just 15 grams, and the largest one, the ostrich, weighs in at 200 kilograms. All the studied birds were revealed to use the MEAD mechanism, just as humans do. In the human voice box (larynx), air from the lungs is pushed past the vocal cords, which then start moving back and forth sideways like a flag fluttering in the wind. With each oscillation, the larynx closes and opens, making the airflow stop and start, which creates sound pulses.

Snake Limb Loss Linked to Ancient Ancestors Evolving to Live & Hunt in Burrows; Analysis of Inner Ear Structure in 90-Million-Year-Old Reptile Skull Provides New Evidence

Fresh analysis of a 90-million-year-old reptile fossil is helping scientists solve an evolutionary puzzle - how snakes lost their limbs. The skull is giving researchers vital clues about how snakes evolved. Comparisons between CT scans of the fossil and modern reptiles indicate that snakes lost their legs when their ancestors evolved to live and hunt in burrows, which many snakes still do today. The findings show snakes did not lose their limbs in order to live in the sea, as was previously suggested. Scientists used CT scans to examine the bony inner ear of Dinilysia patagonica, a 2-meter-long reptile closely linked to modern snakes. These bony canals and cavities, like those in the ears of modern burrowing snakes, controlled the ancient reptile’s hearing and balance. The scientists constructed 3D virtual models to compare the inner ears of the fossils with those of modern lizards and snakes. Researchers found a distinctive structure within the inner ear of animals that actively burrow, which may help them detect prey and predators. This shape is not present in modern snakes that live in water or above ground. The new findings help scientists fill gaps in the story of snake evolution, and confirm Dinilysia patagonica as the largest burrowing snake ever known. The findings also offer clues about a hypothetical ancestral species from which all modern snakes descended, which was likely a burrower. The study, published recently in Science Advances, was supported by the Royal Society. Dr. Hongyu Yi, of the University of Edinburgh's School of GeoSciences, who led the research, said: "How snakes lost their legs has long been a mystery to scientists, but it seems that this happened when their ancestors became adept at burrowing.

Beta-Amyloid-Mediated Breakdown of Neural Cell Adhesion Molecule (NCAM2) Implicated in Newly Discovered Mechanism of Synapse Loss in Alzheimer’s Disease; May Point Way to Possible New Treatment Approaches

A team of researchers led by scientists at Australia’s University of New South Wales (UNSW) has discovered how connections between brain cells are destroyed in the early stages of Alzheimer's disease - work that opens up a new avenue for research on possible treatments for the degenerative brain condition. "One of the first signs of Alzheimer's disease is the loss of synapses - the structures that connect neurons in the brain," says study leader, Dr. Vladimir Sytnyk, of the UNSW School of Biotechnology and Biomolecular Sciences. "Synapses are required for all brain functions, and particularly for learning and forming memories. In Alzheimer's disease, this loss of synapses occurs very early on, when people still only have mild cognitive impairment, and long before the nerve cells themselves die. "We have identified a new molecular mechanism which directly contributes to this synapse loss - a discovery we hope could eventually lead to earlier diagnosis of the disease and new treatments." The team studied a protein in the brain called neural cell adhesion molecule 2 (NCAM2) - one of a family of molecules that physically connects the membranes of synapses and help stabilise these long lasting synaptic contacts between neurons. The research was published online on November 27, 2015 in an open-access article Nature Communications. The article is titled “Aβ-Dependent Reduction of NCAM2-Mediated Synaptic Adhesion Contributes to Synapse Loss in Alzheimer’s Disease.” Using post-mortem brain tissue from people with and without the condition, they discovered that synaptic NCAM2 levels in the part of the brain known as the hippocampus were low in those with Alzheimer's disease.