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Archive - Oct 31, 2015

Optogenetics Used to Show That Axon Initial Segments (AIS’s) Can Change Length and Influence Repetitive Spike Firing Much More Rapidly Than Previously Thought

Neurons communicate by passing electrical messages, known as action potentials, between each other. Each neuron has a highly specialized structural region, the so-called “axon initial segment” (AIS), whose primary role is in the generation and sending of these messages. The AIS can undergo changes in size, length, and location in response to alterations of a neuron's ongoing electrical activity. However, until now, all such “AIS plasticity” has been believed to be exceptionally slow, occurring over a timescale of days. Work by researchers from the MRC Centre for Developmental Neurobiology (MRC CDN), part of the Institute of Psychiatry, Psychology & Neuroscience at King's College London at King’s College London, has now shown that AIS changes can occur much more quickly, influencing the way cells fire action potentials. These results were published online on October 29, 2015 in an open-access article in the journal Cell Reports. The article is titled “Rapid Modulation of Axon Initial Segment Length Influences Repetitive Spike Firing.” Located near the beginning of the axon, which is the neuron's major output structure, the AIS has a crucial role in kick-starting communication between brain cells. However, for AIS plasticity to play a more prominent role in the brain's responses to altered activity, the structure needs to be able to change far more quickly than has previously been shown. For this reason, Dr. Mark Evans (now at the Gladstone Institute of Neurological Disease in San Francisco), Dr. Adna Dumitrescu, Dr. Dennis Kruijssen, Dr. Samuel Taylor, and Dr. Matthew Grubb decided to investigate how rapidly an AIS can be altered.

Semi-Automated Method Developed to ID European Corn Borer; Destructive Pest Causes $2 Billion in Damage Annually in U.S. Alone; Wing Venation Pattern in Corn Borer Moths Is Key; Improved ID May Allow Better Control of This Pest

Farmers who need to control the destructive European corn borer (Ostrinia nubilalis) may soon be able to distinguish it from look-alike species by simply scanning an image of its wing into a computer and tapping a few keys. A technique developed by Polish scientists marks the first time that measurements of key structural features in the wing have been used to identify the borer, a potentially major advance in controlling the pest. The new identification method was developed by Dr. Lukasz Przybylowicsz, Dr. Michal Pniak, and Dr. Adam Tofilski, and it is described in an open-access article published online on October 20, 2015 in the Journal of Economic Entomology. The article is titled “Semiautomated Identification of European Corn Borer (Lepidoptera: Crambidae.” The European corn borer is a prime pest on corn, but also impacts more than 200 other crops, and, by some estimates, causes up to $2 billion in damage annually in the United States alone. Most farmers are not able to identify adult corn borers or distinguish these destructive pests from other species. The identification method developed by the scientists focuses on the arrangement of veins in the wings of the moths, applying a technique known as geometric morphometry. Essentially, it examines and compares the geometry of an organism's structures -- in other words, where its parts are positioned in relation to one another. Computerized statistical analysis is key to attaining results. The researchers selected nine points -- called "landmarks" -- at junctions of veins in the central part of the wing. Landmarks, such as where veins join, are a common feature among species.

UK Study Shows Climate Change Affecting Different Butterfly & Moth Species Differently; Some Increasing in Number, Some Decreasing; Varied Responses Viewed As "Surprising" for Cool, Rainy Britain

New research led by ecologists at the University of York shows that certain species of moths and butterflies are becoming more common, and others rarer, as species differ in how they respond to climate change. Collaborating with the Natural Environment Research Council's Centre for Ecology and Hydrology, the charity Butterfly Conservation, the University of Reading, and Rothamsted Research, scientists analyzed how the abundance and distribution of 155 species of British butterflies and moths have changed since the 1970s. Using data collected by thousands of volunteers through “citizen science” schemes, responses to recent climate change were seen to vary greatly from species to species. Published in an open-access article in the October 2, 2015 issue of Science Advances, this research shows that variation among species can be attributed to differing sensitivity to climate change, and also because species vary in how much the climate has changed for them (their “exposure”). The article is titled “Individualistic Sensitivities and Exposure to Climate Change Explain Variation in Species’ Distribution and Abundance Changes.” Sensitivity is a measure of how much species' numbers change as a result of year-to-year changes in the weather - each species is sensitive to different aspects of the climate, such as winter temperature or summer rainfall. Variation in how much the climate they are sensitive to has changed for them - their “exposure” - is also a contributing factor in their varied responses. Results show that species such as the treble brown spot moth (Idaea trigeminata) and the speckled wood butterfly (Pararge aegeria)(image) which are sensitive to climate, and for which the climate has improved the most, have experienced the greatest increases in their distribution size and abundance.