The ‘Pritchard Trap’: a novel quantitative survey method for crayfish

1. As crayfish invasions continue to threaten native freshwater biota, a detailed understanding of crayfish distribution and population structure becomes imperative. Nonetheless, most current survey methods provide inadequate demographic data. The quantitative ‘Triple Drawdown’ (TDD) dewatering method has highlighted the importance of such data, yet practical constraints prevent its large-scale application. 2. Here, we introduce the ‘Pritchard Trap’, a novel passive sampling method that reliably generates quantitative crayfish population data while requiring substantially lower sampling effort than TDDs. This quadrat-style sampler was extensively tested in headwater streams of North Yorkshire, England, along an invasion gradient for signal crayfish (Pacifastacus leniusculus) from well-established sites to mixed populations of signal crayfish and native white-clawed crayfish (Austropotamobius pallipes). 3. The Pritchard Trap was trialled over several time intervals to determine the minimum required trap deployment time. TDDs at the same sites allowed for a robust evaluation of Pritchard Trap sampling accuracy in representing crayfish densities and population structure. 4. The Pritchard Trap successfully sampled both invasive and native crayfish (8–42 mm carapace length). A minimum passive deployment time of 4 days was required. At low crayfish densities (0.5 individuals m−2), increased trapping effort was necessary to achieve accurate population density and size class distribution estimates. The Pritchard Trap required substantially less sampling effort (working hours) and resources than the TDD, whilst also posing less risk to non-target species. 5. The Pritchard Trap, for the first time, affords logistically simple, truly quantitative investigations of crayfish population demographics for headwater systems. It could be integrated into crayfish research and management, for example to explore density-dependent ecological impacts of invasive crayfish and their management responses or to monitor populations and recruitment in native crayfish conservation initiatives

Lymphoma incidence, survival and prevalence 2004–2014 : sub-type analyses from the UK’s Haematological Malignancy Research Network

Background: Population-based information about cancer occurrence and survival are required to inform clinical practice and research; but for most lymphomas data are lacking. Methods: Set within a socio-demographically representative UK population of nearly 4 million, lymphoma data (N ¼ 5796) are from an established patient cohort. Results: Incidence, survival (overall and relative) and prevalence estimates for 420 subtypes are presented. With few exceptions, males tended to be diagnosed at younger ages and have significantly (Po0.05) higher incidence rates. Differences were greatest at younger ages: the o15 year male/female rate ratio for all subtypes combined being 2.2 (95% CI 1.3–3.4). These gender differences impacted on prevalence; most subtype estimates being significantly (Po0.05) higher in males than females. Outcome varied widely by subtype; survival of patients with nodular lymphocyte predominant Hodgkin lymphoma approached that of the general population, whereas less than a third of those with other B-cell (e.g., mantle cell) or T-cell (e.g., peripheral-T) lymphomas survived for Z5 years. No males/female survival differences were detected. Conclusions: Major strengths of our study include completeness of ascertainment, world-class diagnostics and generalisability. The marked variations demonstrated confirm the requirement for ‘real-world’ data to inform aetiological hypotheses, health-care planning and the future monitoring of therapeutic changes

DDX3X suppresses the susceptibility of hindbrain lineages to medulloblastoma

DEAD-Box Helicase 3 X-Linked (DDX3X) is frequently mutated in the Wingless (WNT) and Sonic hedghog (SHH) subtypes of medulloblastoma—the commonest malignant childhood brain tumor, but whether DDX3X functions as a medulloblastoma oncogene or tumor suppressor gene is not known. Here, we show that Ddx3x regulates hindbrain patterning and development by controlling Hox gene expression and cell stress signaling. In mice predisposed to Wnt- or Shh medulloblastoma, Ddx3x sensed oncogenic stress and suppressed tumor formation. WNT and SHH medulloblastomas normally arise only in the lower and upper rhombic lips, respectively. Deletion of Ddx3x removed this lineage restriction, enabling both medulloblastoma subtypes to arise in either germinal zone. Thus, DDX3X is a medulloblastoma tumor suppressor that regulates hindbrain development and restricts the competence of cell lineages to form medulloblastoma subtypes

Generation of a Homozygous Transgenic Rat Strain Stably Expressing a Calcium Sensor Protein for Direct Examination of Calcium Signaling

In drug discovery, prediction of selectivity and toxicity require the evaluation of cellular calcium homeostasis. The rat is a preferred laboratory animal for pharmacology and toxicology studies, while currently no calcium indicator protein expressing rat model is available. We established a transgenic rat strain stably expressing the GCaMP2 fluorescent calcium sensor by a transposon-based methodology. Zygotes were co-injected with mRNA of transposase and a CAG- GCaMP2 expressing construct, and animals with one transgene copy were pre-selected by measuring fluorescence in blood cells. A homozygous rat strain was generated with high sensor protein expression in the heart, kidney, liver, and blood cells. No pathological alterations were found in these animals, and fluorescence measurements in cardiac tissue slices and primary cultures demonstrated the applicability of this system for studying calcium signaling. We show here that the GCaMP2 expressing rat cardiomyocytes allow the prediction of cardiotoxic drug side-effects, and provide evidence for the role of Na+/Ca2+ exchanger and its beneficial pharmacological modulation in cardiac reperfusion. Our data indicate that drug-induced alterations and pathological processes can be followed by using this rat model, suggesting that transgenic rats expressing a calcium-sensitive protein provide a valuable system for pharmacological and toxicological studies

Connectivity and zebra mussel invasion offer short‐term buffering of eutrophication impacts on floodplain lake landscape biodiversity

Aim To investigate if connectivity and zebra mussel (Dreissena polymorpha) occurrence can mitigate effects of eutrophication in a lowland lake landscape. Location Upper Lough Erne, Northern Ireland, UK. Methods Data on environment, macrophytes and invertebrates were assembled for three basins of a large central lake and its satellite floodplain lakes via field surveys and palaeolimnological analyses. Space–time interaction analyses of palaeoecological data were compared pre‐1950 and post‐1950. Multivariate analyses examined how connectivity, environment and zebra mussels influenced contemporary lake communities, and explain their divergence from historical communities in the past. Results Pre‐1950, we found high community variation across sites and low within‐lake variation in macrophytes, but progressive eutrophication accentuated within‐lake community variation after 1950. Partitioning analysis showed larger effects of connectivity than nutrient enrichment on contemporary macrophyte composition, while local effects structured invertebrate communities. Three clusters of lakes were revealed according to variation in macrophyte composition, isolation from the central lake and nutrient enrichment: Group 1– the central lake and six nearby lakes were meso‐eutrophic (TP = 66.7 ± 47.6 μg/L; TN = 0.79 ± 0.41 mg/L) and had the highest zebra mussel abundances and organismal biodiversity; Group 2– Eight eutrophic (TP = 112±36.6 μg/L; TN = 1.25 ± 0.5 mg/L) and connected lakes; Group 3– Seven isolated and hypertrophic (TP = 163.2 ± 101.5 μg/L; TN = 1.55 ± 0.3 mg/L) lakes. Pre‐1950 palaeolimnological data for macrophytes and invertebrates for 5 lakes and a basin in the central lake most resembled extant lake communities of Group 1. However, palaeo‐records revealed that macrophytes and invertebrates subsequently converged towards those of Groups 2 and 3. Main conclusions Our study reveals that the central “mother” lake acts as a hub for preserving biodiversity via shared hydrological connectivity with satellite lakes and high zebra mussel abundances. These may buffer the impoverishing effects of eutrophication and sustain unexpectedly high biodiversity in the short term. Such protective buffering, however, cannot be relied upon indefinitely to conserve biodiversity