Distribution of the meadow lizard in Europe and its realized ecological niche model

One of the most interesting but elusive members of the European herpetofauna is the meadow lizard (Darevskia praticola). It is a small, ground dwelling, predominantly forest living lacertid, for which many ecological and biological data are still missing. Moreover, at least for the western part of the species range (south-eastern Europe) its distribution and environmental associations are insufficiently known, likely due to difficulties in detection even with intensive field sampling. Here, we complemented the available literature records with our personal observations and explored the effects of environmental factors shaping the species ecological niche and distribution in Europe using the ecological niche modelling approach from Maxent software. The new records of the meadow lizard fill a gap in its known distribution. The most suitable habitats are in central and eastern Serbia, south-western Romania, and central, southern and south-western Bulgaria. Mean temperature of the coldest quarter, vegetation and slope had the strongest effect in defining the meadow lizard’s ecological niche. Niche suitability increased with the increase in forest cover and slope, while the temperature showed a bell-shaped response with a rather narrow tolerance range for temperature. Contrary to expectations, precipitation seemed to have no contribution to the species occurrence. Ecological niche model performance increased with a higher resolution of predictor variables despite the lower number of available occurrence records, although the slope variable had a greater predictive power when calculated at a lower resolution. Interestingly, high resolution vegetation variables (30 m) were able to show some level of habitat fragmentation, which likely resulted from deforestation. Overall, our results epitomize the effects of limited sampling on the biogeography inference of elusive species while having significant repercussions on conservation priorities and management of the species.     

Two new species of the genus Pseudolaelaps Berlese, 1916 (Acari: Mesostigmata: Pseudolaelapidae) from Europe,with an updated key to known species

Pseudolaelaps calvescens sp. nov. and Pseudolaelaps schweizeri sp. nov. (Acari: Pseudolaelapidae) are described based on female specimens from leaf litter and soil of forest habitats in Italy (surroundings of Bergamo) and Switzerland (surroundings of Basel), respectively. The British specimens referred to Pseudolaelaps doderoi are revised, and considered to be a misidentification of P. schweizeri sp. nov. An identification key to known species of the genus Pseudolaelaps is provided.

www.zoobank.org/urn:lsid:zoobank.org:pub:92F3907A-9C0A-4309-8D1E-BC5F3E7D937B     

Gold nanoparticles induce nuclear damage in breast cancer cells,which is further amplified by hyperthermia

Gold nanoparticles have emerged as promising tools for cancer research and therapy, where they can promote thermal killing. The molecular mechanisms underlying these events are not fully understood. The geometry and size of gold nanoparticles can determine the severity of cellular damage. Therefore, small and big gold nanospheres as well as gold nanoflowers were evaluated side-by-side. To obtain quantitative data at the subcellular and molecular level, we assessed how gold nanoparticles, either alone or in combination with mild hyperthermia, altered the physiology of cultured human breast cancer cells. Our analyses focused on the nucleus, because this organelle is essential for cell survival. We showed that all the examined gold nanoparticles associated with nuclei. However, their biological effects were quantitatively different. Thus, depending on the shape and size, gold nanoparticles changed multiple nuclear parameters. They redistributed stress-sensitive regulators of nuclear biology, altered the nuclear morphology, reorganized nuclear laminae and envelopes, and inhibited nucleolar functions. In particular, gold nanoparticles reduced the de novo biosynthesis of RNA in nucleoli, the subnuclear compartments that produce ribosomes. While small gold nanospheres and nanoflowers, but not big gold nanospheres, damaged the nucleus at normal growth temperature, several of these defects were further exacerbated by mild hyperthermia. Taken together, the toxicity of gold nanoparticles correlated with changes in nuclear organization and function. These results emphasize that the cell nucleus is a prominent target for gold nanoparticles of different morphologies. Moreover, we demonstrated that RNA synthesis in nucleoli provides quantitative information on nuclear damage and cancer cell survival.     

Progress and prospects in rat genetics: a community view

The rat is an important system for modeling human disease. Four years ago, the rich 150-year history of rat research was transformed by the sequencing of the rat genome, ushering in an era of exceptional opportunity for identifying genes and pathways underlying disease phenotypes. Genome-wide association studies in human populations have recently provided a direct approach for finding robust genetic associations in common diseases, but identifying the precise genes and their mechanisms of action remains problematic. In the context of significant progress in rat genomic resources over the past decade, we outline achievements in rat gene discovery to date, show how these findings have been translated to human disease, and document an increasing pace of discovery of new disease genes, pathways and mechanisms. Finally, we present a set of principles that justify continuing and strengthening genetic studies in the rat model, and further development of genomic infrastructure for rat research.     

Distribution and functional impact of DNA copy number variation in the rat

The abundance and dynamics of copy number variants (CNVs) in mammalian genomes poses new challenges in the identification of their impact on natural and disease phenotypes. We used computational and experimental methods to catalog CNVs in rat and found that they share important functional characteristics with those in human. In addition, 113 one-to-one orthologous genes overlap CNVs in both human and rat, 80 of which are implicated in human disease. CNVs are nonrandomly distributed throughout the genome. Chromosome 18 is a cold spot for CNVs as well as evolutionary rearrangements and segmental duplications, suggesting stringent selective mechanisms underlying CNV genesis or maintenance. By exploiting gene expression data available for rat recombinant inbred lines, we established the functional relationship of CNVs underlying 22 expression quantitative trait loci. These characteristics make the rat an excellent model for studying phenotypic effects of structural variation in relation to human complex traits and disease.     

Polar transport of the plant hormone auxin – the role of PIN-FORMED (PIN) proteins

The PIN-FORMED (PIN) protein family is a group of plant transmembrane proteins with a predicted function as secondary transporters. PINs have been shown to play a rate-limiting role in the catalysis of efflux of the plant growth regulator auxin from cells, and their asymmetrical cellular localization determines the direction of cell-to-cell auxin flow. There is a functional redundancy of PINs and their biochemical activity is regulated at many levels. PINs constitute a flexible network underlying the directional auxin flux (polar auxin transport) which provides cells in any part of the plant body with particular positional and temporal information. Thus, the PIN network, together with downstream auxin signalling system(s), coordinates plant development. This review summarizes recent progress in the elucidation of the role of PIN proteins in polar auxin transport at the cellular level, with emphasis on their structure and evolution and regulation of their function. Received 28 December 2006; received after revision 16 February 2007; accepted 26 March 2007     

Combining Association Measures for Collocation Extraction Using Clustering of Receiver Operating Characteristic Curves

This paper focuses on combining association measures using corresponding receiver operating characteristic curves. The approach is motivated by a problem of automatic bigram collocation extraction from the field of computational linguistics. It is based on supervised machine learning techniques and the fact that different association measures discover different collocation types. Clusters of equivalent ROC curves are first determined by a testing procedure. The paper’s major contribution is an investigation of the possibility of combining representatives of the clusters of equivalent association measures into more complex models, thus improving performance of the collocation extraction.