Ring tests to evaluate the performance of Porcine circovirus-2 (PCV-2) polymerase chain reaction (PCR) assays used in North American diagnostic laboratories

Two laboratory studies involving 11 laboratories were undertaken to assess the performance of North American Porcine circovirus-2 (PCV-2) polymerase chain reaction (PCR) assays. Laboratories received identical submissions containing randomly coded positive and negative control samples, and serially diluted PCV-2-spiked samples. In study 1 and 2, respectively, spiked samples contained measured amounts of PCV-2 virus or DNA. All but 1 assay detected DNA in the most concentrated spiked sample. There were no statistical differences in the proportion of positive or negative samples reported by quantitative (n = 7) versus non-quantitative (n = 6) assays. Across both studies, the false positive rate was 17% (4 out of 23), and 17% (2 out of 12) of assays cross-reacted with PCV-1. The most sensitive assay detected PCV-2 DNA levels about 100 000 times lower the least sensitive assay. This study demonstrated that the PCR assays available in North American diagnostic labs vary considerably in their detection limits and quantification.     

Pan‐continental invasion of Pseudorasbora parva: towards a better understanding of freshwater fish invasions

In recent years, policy‐makers have sought the development of appropriate tools to prevent and manage introductions of invasive species. However, these tools are not well suited for introductions of non‐target species that are unknowingly released alongside intentionally‐introduced species. The most compelling example of such invasion is arguably the topmouth gudgeon Pseudorasbora parva, a small cyprinid species originating from East Asia. A combination of sociological, economical and biological factors has fuelled their rapid invasion since the 1960s; 32 countries (from Central Asia to North Africa) have been invaded in less than 50 years. Based on a combination of monitoring surveys (2535 populations sampled) and literature reviews, this paper aims to quantify and characterise important invasion parameters, such as pathways of introduction, time between introduction and detection, lag phase and plasticity of life history traits. Every decade, five new countries have reported P. parva introduction, mainly resulting from the movement of Chinese carps for fish farming. The mean detection period after first introduction was 4 years, a duration insufficient to prevent their pan‐continental invasion. High phenotypic plasticity in fitness related traits such as growth, early maturity, fecundity, reproductive behaviour and the ability to cope with novel pathogens has predisposed P. parva to being a strong invader. The Pseudorasbora parva invasion has provided quantitative data for the development of 1) early warning systems across different spatial scales; 2) rapid eradication programmes prior to natural spread in open systems and 3) sound risk assessments with emphasis on plasticity of life history traits.     

Contemporary climate infuence on variability patterns of Anadenanthera colubrina var. cebil,a key species in seasonally dry tropical forestsOA

The distribution of many plant species has been shaped by climate changes, and their current phenotypic and genetic variability refect microclimatically suitable habitats. This study relates contemporary climate to variability patterns of phenotypic traits and molecular markers in the Argentinean distribution of Anadenanthera colubrina var.cebil, as well as to identify the most relevant phenotypic trait or molecular marker associated with those patterns.Individuals from four populations in both ...