Pathological and ecological host consequences of infection by an introduced fish parasite

The infection consequences of the introduced cestode fish parasite Bothriocephalus acheilognathi were studied in a cohort of wild, young-of-the-year common carp Cyprinus carpio that lacked co-evolution with the parasite. Within the cohort, parasite prevalence was 42% and parasite burdens were up to 12% body weight. Pathological changes within the intestinal tract of parasitized carp included distension of the gut wall, epithelial compression and degeneration, pressure necrosis and varied inflammatory changes. These were most pronounced in regions containing the largest proportion of mature proglottids. Although the body lengths of parasitized and non-parasitized fish were not significantly different, parasitized fish were of lower body condition and reduced weight compared to non-parasitized conspecifics. Stable isotope analysis (δ15N and δ13C) revealed trophic impacts associated with infection, particularly for δ15N where values for parasitized fish were significantly reduced as their parasite burden increased. In a controlled aquarium environment where the fish were fed ad libitum on an identical food source, there was no significant difference in values of δ15N and δ13C between parasitized and non-parasitized fish. The growth consequences remained, however, with parasitized fish growing significantly slower than non-parasitized fish, with their feeding rate (items s−1) also significantly lower. Thus, infection by an introduced parasite had multiple pathological, ecological and trophic impacts on a host with no experience of the parasite

Coherent motion of stereocilia assures the concerted gating of hair-cell transduction channels

The hair cell's mechanoreceptive organelle, the hair bundle, is highly sensitive because its transduction channels open over a very narrow range of displacements. The synchronous gating of transduction channels also underlies the active hair-bundle motility that amplifies and tunes responsiveness. The extent to which the gating of independent transduction channels is coordinated depends on how tightly individual stereocilia are constrained to move as a unit. Using dual-beam interferometry in the bullfrog's sacculus, we found that thermal movements of stereocilia located as far apart as a bundle's opposite edges display high coherence and negligible phase lag. Because the mechanical degrees of freedom of stereocilia are strongly constrained, a force applied anywhere in the hair bundle deflects the structure as a unit. This feature assures the concerted gating of transduction channels that maximizes the sensitivity of mechanoelectrical transduction and enhances the hair bundle's capacity to amplify its inputs.Comment: 24 pages, including 6 figures, published in 200

Analogues of Kahan's method for higher order equations of higher degree

Kahan introduced an explicit method of discretization for systems of first order differential equations with nonlinearities of degree at most two (quadratic vector fields). Kahan's method has attracted much interest due to the fact that it preserves many of the geometrical properties of the original continuous system. In particular, a large number of Hamiltonian systems of quadratic vector fields are known for which their Kahan discretization is a discrete integrable system. In this note, we introduce a special class of explicit order-preserving discretization schemes that are appropriate for certain systems of ordinary differential equations of higher order and higher degree

Does BCR/ABL1 positive Acute Myeloid Leukaemia Exist?

The BCR/ABL1 fusion gene, usually carried by the Philadelphia chromosome (Ph) resulting from t(9;22)(q34;q11) or variants, is pathognomonic for chronic myeloid leukaemia (CML). It is also occasionally found in acute lymphoblastic leukaemia (ALL) mostly in adults and rarely in de novo acute myeloid leukaemia (AML). Array Comparative Genomic Hybridization (aCGH) was used to study six Ph(+)AML, three bi-lineage and four Ph(+)ALL searching for specific genomic profiles. Surprisingly, loss of the IKZF1 and/or CDKN2A genes, the hallmark of Ph(+)ALL, were recurrent findings in Ph(+)AML and accompanied cryptic deletions within the immunoglobulin and T cell receptor genes. The latter two losses have been shown to be part of 'hot spot' genome imbalances associated with BCR/ABL1 positive pre-B lymphoid phenotype in CML and Ph(+)ALL. We applied Significance Analysis of Microarrays (SAM) to data from the 'hot spot' regions to the Ph(+)AML and a further 40 BCR/ABL1(+) samples looking for differentiating features. After exclusion of the most dominant markers, SAM identified aberrations unique to de novo Ph(+)AML that involved relevant genes. While the biological and clinical significance of this specific genome signature remains to be uncovered, the unique loss within the immunoglobulin genes provides a simple test to enable the differentiation of clinically similar de novo Ph(+) AML and myeloid blast crisis of CML. © 2013 John Wiley & Sons Ltd and Crown

Prioritising references for systematic reviews with RobotAnalyst: A user study

Screening references is a time-consuming step necessary for systematic reviews and guideline development. Previous studies have shown that human effort can be reduced by using machine learning software to prioritise large reference collections such that most of the relevant references are identified before screening is completed. We describe and evaluate RobotAnalyst, a Web-based software system that combines text-mining and machine learning algorithms for organising references by their content and actively prioritising them based on a relevancy classification model trained and updated throughout the process. We report an evaluation over 22 reference collections (most are related to public health topics) screened using RobotAnalyst with a total of 43 610 abstract-level decisions. The number of references that needed to be screened to identify 95% of the abstract-level inclusions for the evidence review was reduced on 19 of the 22 collections. Significant gains over random sampling were achieved for all reviews conducted with active prioritisation, as compared with only two of five when prioritisation was not used. RobotAnalyst's descriptive clustering and topic modelling functionalities were also evaluated by public health analysts. Descriptive clustering provided more coherent organisation than topic modelling, and the content of the clusters was apparent to the users across a varying number of clusters. This is the first large-scale study using technology-assisted screening to perform new reviews, and the positive results provide empirical evidence that RobotAnalyst can accelerate the identification of relevant studies. The results also highlight the issue of user complacency and the need for a stopping criterion to realise the work savings

Introduced Pathogens and Native Freshwater Biodiversity: A Case Study of Sphaerothecum destruens

A recent threat to European fish diversity was attributed to the association between an intracellular parasite, Sphaerothecum destruens, and a healthy freshwater fish carrier, the invasive Pseudorasbora parva originating from China. The pathogen was found to be responsible for the decline and local extinction of the European endangered cyprinid Leucaspius delineatus and high mortalities in stocks of Chinook and Atlantic salmon in the USA. Here, we show that the emerging S. destruens is also a threat to a wider range of freshwater fish than originally suspected such as bream, common carp, and roach. This is a true generalist as an analysis of susceptible hosts shows that S. destruens is not limited to a phylogenetically narrow host spectrum. This disease agent is a threat to fish biodiversity as it can amplify within multiple hosts and cause high mortalities

Tracing Sagittarius Structure with SDSS and SEGUE Imaging and Spectroscopy

We show that the Sagittarius dwarf tidal stream can be traced with very red K/M-giant stars selected from SDSS photometry. A subset of these stars are spectroscopically confirmed with SEGUE and SDSS spectra, and the distance scale of 2MASS and SDSS M giants is calibrated to the RR Lyrae distance scale. The absolute g band magnitude of the K/M-giant stars at the tip of the giant branch is M_g=-1.0. The line-of-sight velocities of the M giant and BHB stars that are spatially coincident with the Sgr dwarf tidal stream are consistent with those of previous authors, reinforcing the need for new models that can explain all of the Sgr tidal debris stream observations. We estimate stellar densities along the tidal tails that can be used to help constrain future models. The K/M-giant, BHB, and F-turnoff stars in the lower surface brightness tidal stream that is adjacent to the main leading Sgr dwarf tidal tail have velocities and metallicities that are similar to those of the stars in the leading tidal tail. The ratio of K/M giants to BHBs and BHBs to F-turnoff stars are also similar for both branches of the leading tidal tail. We show that there is an additional low-metallicity tidal stream near the Sgr trailing tidal tail.Comment: 19 figures, accepted for publication in ApJ, references update