Quantifying bioturbation of a simulated ash fall event

Tephrochronology allows the establishment of ‘isochrons’ between marine, lacustrine, terrestrial and ice cores, typically based on the geochemical fingerprint of the tephra. The development of cryptotephrochronology has revealed a vast inventory of isochrons which hold the potential to improve stratigraphic correlation and identify systemic leads and lags in periods of rapid climate change. Unfortunately, bioturbation acts to blur these isochrons, reducing the temporal resolution in marine and lacustrine records. In order to better resolve these event horizons, we require a better understanding of bioturbative processes, and the depth and time over which they operate. To this end, an ash fall event was simulated on the intertidal zone of the Eden Estuary, Fife, Scotland and sediment cores were collected over 10 days. A novel approach to tephra quantification was developed, using the imaging software ImageJ. Our results showed limited bioturbation (mixed depth=18 mm), most likely owing to the fine grain size, low-energy environment and the resulting faunal composition of the sediments. These results imply a strong ecological control on bioturbation, and suggest that inferences may be made about palaeoenvironments from the observed bioturbation profile

Anticancer drug vinblastine sulphate induces transient morphological changes on the olfactory mucosa of the rabbit

Vinblastine sulphate (VBS) is an anticancer drug that acts by disrupting microtubule dynamics of highly mitotic tissue cells. The consequences of VBS on the olfactory mucosa (OM), a tissue with high mitotic numbers, are not clearly understood. We used qualitative and quantitative methods to determine the structural changes that may be produced on the rabbit OM by VBS. Following a single dose (0.31 mg/kg) of this drug, the structure of the mucosa was greatly altered on the first 3-5 days. The alteration was characterized by disarrangement of the normal layering of nuclei of the epithelia, degeneration of axonal bundles, occurrence of blood vessels within the bundles, localized death of cells of Bowman's glands and glandular degeneration. Surprisingly on or after day 7 and progressively to day 15 post-exposure, the OM was observed to regenerate and acquire normal morphology, and the vessels disappeared from the bundles. Relative to control values, bundle diameters, olfactory cell densities and cilia numbers decreased to as low as 53.1, 75.2 and 71.4%, respectively, on day 5. Volume density for the bundles, which was 28.6% in controls, decreased to a lowest value of 16.8% on day 5. In contrast, the volume density for the blood vessels was significantly lower in controls (19.9%) than in treated animals at day 2 (25.8%), day 3 (34.3%) and day 5 (31.5%). These findings suggest that the changes induced on the rabbit OM by VBS are transient and that regenerative recovery leads to the restoration of the normal structure of the mucosa

Data from: Opportunistic records reveal Mediterranean reptiles’ scale‐dependent responses to anthropogenic land use

Although classified among the greatest threats to the world's biodiversity, the effects of land use and their scale dependency are left unexplored in many taxonomic groups. Reptiles are among the most data‐deficient vertebrates in this respect, although their ecological traits make them highly sensitive to habitat modifications. We tested whether land use gradients shape the distributions of Mediterranean reptiles at regional and local scales, and whether species’ ecological traits and phylogeny explain these patterns. Reptiles are generally rare and hard to survey through standardized protocols. We overcame these obstacles by modeling an original data set of 18164 opportunistic occurrence records for 14 reptile species with spatially‐explicit point process models incorporating known sources of sampling heterogeneity and spatially autocorrelated error. At a regional scale, reptiles favored open habitats and tended to avoid urban areas. At a local scale, the persistence of open habitats did better than forest resulting from land abandonment in maintaining reptiles within a heavily anthropogenic matrix. Contrary to our expectations, the absence of any clear trait or phylogenetic signals suggests that these responses are mediated by a complex interplay between species’ ecology and regional biogeographic history. These results demonstrate that reptile responses to land use are scale‐dependent and locally exacerbated when anthropogenic pressure is high. We further show that land abandonment is insufficient to preserve reptiles in the face of anthropogenic pressures unless patches of suitable habitat are effectively maintained. Eventually, our study further illustrates the effectiveness of volunteer‐based opportunistic sampling in testing hypotheses on the determinants of rare species’ distributions

An evaluation of the validity of the Test of Visual Perceptual Skills - Revised (TVPS-R) using the Rasch Measurement Model

The visual perceptual skills of children are often evaluated by health care and education practitioners. Even though the Test of Visual Perceptual Skills - Revised (TVPS-R) is one of the most frequently used instruments with school-age children, its construct validity has not been evaluated thoroughly. The purpose of the study was to evaluate the scalability/interval level measurement, unidimensionality, lack of differential item functioning (DIF), and hierarchical ordering of items of the TVPS-R and its seven subscales using the Rasch Measurement Model (RMM). The TVPS-R scores from a sample of 356 normally developing children (171 boys and 185 girls), ranging in age from 5 to 11 years, were used to complete the RMM analysis. When the seven individual TVPS-R scales were analysed, they all exhibited adequate measurement properties (scalability/interval level measurement, unidimensionality, lack of DIF, and hierarchical ordering). However, when they were collapsed together to form an overall composite scale of motor-free visual perceptual skills, the TVPS-R items failed to group together to measure a unidimensional construct. In addition, many scale items exhibited RMM misfit or DIF. The results suggest that the seven TVPS-R subscales can be used on an individual basis with clients to generate a profile of their motor-free visual perceptual skills, but that they cannot be summed together to calculate an overall summary motor-free visual perceptual score or perceptual quotient. The TVPS-R composite scale does not exhibit adequate construct validity