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      Phenotypic plasticity in color without molt in adult grasshoppers of the genus Sphingonotus (Acrididae: Oedipodinae)

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      Journal of Orthoptera Research

      Pensoft Publishers

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          Using digital photography to study animal coloration

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            A UV-independent pathway to melanoma carcinogenesis in the redhair-fairskin background

            People with pale skin, red hair, freckles, and an inability to tan—the “redhair/fairskin” phenotype— are at highest risk of developing melanoma, compared to all other pigmentation types 1 . Genetically, this phenotype is frequently the product of inactivating polymorphisms in the Melanocortin 1 receptor (MC1R) gene. MC1R encodes a cAMP stimulating G-protein coupled receptor that controls pigment production. Minimal receptor activity, as in redhair/fairskin polymorphisms, produces red/yellow pheomelanin pigment, while increasing MC1R activity stimulates production of black/brown eumelanin 2 . Pheomelanin has weak UV shielding capacity relative to eumelanin and has been shown to amplify UVA-induced reactive oxygen species (ROS) 3–5 . Several observations, however, complicate the assumption that melanoma risk is completely UV dependent. For example, unlike non-melanoma skin cancers, melanoma is not restricted to sun-exposed skin and UV signature mutations are infrequently oncogenic drivers 6 . While linkage of melanoma risk to UV exposure is beyond doubt, UV-independent events are also likely to play a significant role 1,7 . Here, we introduced into mice carrying an inactivating mutation in the Mc1r gene (who exhibit a phenotype analogous to redhair/fairskin humans), a conditional, melanocyte-targeted allele of the most commonly mutated melanoma oncogene, BRafV600E. We observed a high incidence of invasive melanomas without providing additional gene aberrations or UV exposure. To investigate the mechanism of UV-independent carcinogenesis, we introduced an albino allele, which ablates all pigment production on the Mc1r e/e background. Selective absence of pheomelanin synthesis was protective against melanoma development. In addition, normal Mc1re/e mouse skin was found to have significantly greater oxidative DNA and lipid damage than albino-Mc1re/e mouse skin. These data suggest that the pheomelanin pigment pathway produces UV-independent carcinogenic contributions to melanomagenesis by a mechanism of oxidative damage. While UV protection remains important, additional strategies may be required for optimal melanoma prevention.
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              Image calibration and analysis toolbox – a free software suite for objectively measuring reflectance, colour and pattern

              Summary Quantitative measurements of colour, pattern and morphology are vital to a growing range of disciplines. Digital cameras are readily available and already widely used for making these measurements, having numerous advantages over other techniques, such as spectrometry. However, off‐the‐shelf consumer cameras are designed to produce images for human viewing, meaning that their uncalibrated photographs cannot be used for making reliable, quantitative measurements. Many studies still fail to appreciate this, and of those scientists who are aware of such issues, many are hindered by a lack of usable tools for making objective measurements from photographs. We have developed an image processing toolbox that generates images that are linear with respect to radiance from the RAW files of numerous camera brands and can combine image channels from multispectral cameras, including additional ultraviolet photographs. Images are then normalised using one or more grey standards to control for lighting conditions. This enables objective measures of reflectance and colour using a wide range of consumer cameras. Furthermore, if the camera's spectral sensitivities are known, the software can convert images to correspond to the visual system (cone‐catch values) of a wide range of animals, enabling human and non‐human visual systems to be modelled. The toolbox also provides image analysis tools that can extract luminance (lightness), colour and pattern information. Furthermore, all processing is performed on 32‐bit floating point images rather than commonly used 8‐bit images. This increases precision and reduces the likelihood of data loss through rounding error or saturation of pixels, while also facilitating the measurement of objects with shiny or fluorescent properties. All cameras tested using this software were found to demonstrate a linear response within each image and across a range of exposure times. Cone‐catch mapping functions were highly robust, converting images to several animal visual systems and yielding data that agreed closely with spectrometer‐based estimates. Our imaging toolbox is freely available as an addition to the open source ImageJ software. We believe that it will considerably enhance the appropriate use of digital cameras across multiple areas of biology, in particular researchers aiming to quantify animal and plant visual signals.
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                Author and article information

                Journal
                Journal of Orthoptera Research
                JOR
                Pensoft Publishers
                1937-2426
                1082-6467
                June 28 2017
                June 28 2017
                : 26
                : 21-27
                Article
                10.3897/jor.26.14550
                © 2017

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