1,140 research outputs found

    Genetic structure of pike (Esox lucius) reveals a complex and previously unrecognized colonization history of Ireland

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    Aim: We investigated genetic variation of Irish pike populations and their relationship with European outgroups, in order to elucidate the origin of this species to the island, which is largely assumed to have occurred as a human-mediated introduction over the past few hundred years. We aimed thereby to provide new insights into population structure to improve fisheries and biodiversity management in Irish freshwaters. Location: Ireland, Britain and continental Europe. Methods: A total of 752 pike (Esox lucius) were sampled from 15 locations around Ireland, and 9 continental European sites, and genotyped at six polymorphic microsatellite loci. Patterns and mechanisms of population genetic structure were assessed through a diverse array of methods, including Bayesian clustering, hierarchical analysis of molecular variance, and approximate Bayesian computation. Results: Varying levels of genetic diversity and a high degree of population genetic differentiation were detected. Clear substructure within Ireland was identified, with two main groups being evident. One of the Irish populations showed high similarity with British populations. The other, more widespread, Irish strain did not group with any European population examined. Approximate Bayesian computation suggested that this widespread Irish strain is older, and may have colonized Ireland independently of humans. Main conclusions: Population genetic substructure in Irish pike is high and comparable to the levels observed elsewhere in Europe. A comparison of evolutionary scenarios upholds the possibility that pike may have colonized Ireland in two ‘waves’, the first of which, being independent of human colonization, would represent the first evidence for natural colonization of a non-anadromous 42 freshwater fish to the island of Ireland. Although further investigations using comprehensive genomic techniques will be necessary to confirm this, the present results warrant a reappraisal of current management strategies for this species

    Effect of Pre-and Post-weaning Nutrition and Management on Performance of Weaned Pigs to circa 35 kg.

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    End of Project ReportThe objective of this project was to examine the factors affecting performance (growth rate, appetite, feed conversion efficiency) of pigs in the stage from weaning to 35 kg liveweight. The study involved three stages, creep feeding during the suckling period, management during the first weaner stage (c. 4 weeks from weaning or 6 kg to 15 kg liveweight) and management during the second weaner stage (c. 15 kg to 35 kg liveweight. Creep feed intake before weaning was low c. 2.5 to 3.0 kg per litter but where it was consumed the response in terms of feed conversion efficiency was good with litter weight increasing in weight by about 1.1 kg for each 1 kg creep consumed. Milk replacer in liquid form was very readily consumed but its preparation and feeding is very laborious. Weaning weight was poorly related to post weaning performance and weaning age seemed to be more critical which is probably a reflection of the greater maturity of older animals. In the first weaner stage, feeding of cooked cereal containing diets was found to have little benefit in pig performance. Acidification of feeds is likely to have only a minor influence on pig performance. An experiment on choice feeding of starter and link feeds did not confirm that smaller pigs require a higher quality diet and, in a choice situation will eat a greater proportion of the more nutrient dense diet. In the second weaner stage, comparison of three commercial weaner feeds with a cereal based control diet showed good performance on all four diets. Pigs fed a high lysine weaner diet grew better in the weaner stage but by slaughter those pigs fed the low lysine weaner diet, after all pigs were fed a common finisher diet, had overtaken them. The high lysine group did, however, have leaner carcasses. Residual effects of early nutrition need to be investigated in more detail including the effect of pregnancy feeding on prenatal development and the relationship between prenatal growth and postnatal growth, in particular development of muscle.European Union Structural Funds (EAGGF

    Tissue-specific expression of high-voltage-activated dihydropyridine-sensitive L-type calcium channels

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    The cloning of the cDNA for the α1 subunit of L-type calcium channels revealed that at least two genes (CaCh1 and CaCh2) exist which give rise to several splice variants. The expression of mRNA for these α1 subunits and the skeletal muscle α2/ÎŽ, ÎČ and Îł subunits was studied in rabbit tissues and BC3H1 cells. Nucleic-acid-hybridization studies showed that the mRNA of all subunits are expressed in skeletal muscle, brain, heart and aorta. However, the α1-, ÎČ- and Îł-specific transcripts had different sizes in these tissues. Smooth muscle and heart contain different splice variants of the CaCh2 gene. The α1, ÎČ and Îł mRNA are expressed together in differentiated but not in proliferating BC3H1 cells. A probe specific for the skeletal muscle α2/ÎŽ subunit did not hybridize to poly(A)-rich RNA from BC3H1 cells. These results suggest that different splice variants of the genes for the α1, ÎČ and Îł subunits exist in tissues containing L-type calcium channels, and that their expression is regulated in a coordinate manner

    A History of common carp Cyprinus carpio (L.) in Ireland: A Review

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    This paper represents the most comprehensive and detailed summary of the history of common carp Cyprinus carpio (L.) in Ireland to date. It charts the earliest known introductions of the species to Irish waters, the rise in popularity of recreational angling for the species from c. 1950 onwards, the work carried out to establish the species in Ireland and explains the primary causes of their more recent distribution increase. Much of the historical research material gathered on common carp in Irish waters, including the first recorded details of introduction, is presented here for the first time.Funder: Marine Institut

    Floquet–Bloch solutions in a sawtooth photonic crystal

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    Band structure of a sawtooth photonic crystal for optical wave propagation along the axis of periodicity is investigated. Floquet-Bloch solutions are found and illustrated for the bandgaps, allowed bands, and bandedges of the crystal. Special attention is given to the cases where Floquet-Bloch solutions become periodic functions

    Pressure Induced Hydration Dynamics of Membranes

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    Pressure-jump initiated time-resolved x-ray diffraction studies of dynamics of the hydration of the hexagonal phase in biological membranes show that (i) the relaxation of the unit cell spacing is non-exponential in time; (ii) the Bragg peaks shift smoothly to their final positions without significant broadening or loss in crystalline order. This suggests that the hydration is not diffusion limited but occurs via a rather homogeneous swelling of the whole lattice, described by power law kinetics with an exponent ÎČ=1.3±0.2 \beta = 1.3 \pm 0.2.Comment: REVTEX 3, 10 pages,3 figures(available on request),#

    A Compensatory Mutation Provides Resistance to Disparate HIV Fusion Inhibitor Peptides and Enhances Membrane Fusion

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    Fusion inhibitors are a class of antiretroviral drugs used to prevent entry of HIV into host cells. Many of the fusion inhibitors being developed, including the drug enfuvirtide, are peptides designed to competitively inhibit the viral fusion protein gp41. With the emergence of drug resistance, there is an increased need for effective and unique alternatives within this class of antivirals. One such alternative is a class of cyclic, cationic, antimicrobial peptides known as Ξ-defensins, which are produced by many non-human primates and exhibit broad-spectrum antiviral and antibacterial activity. Currently, the Ξ-defensin analog RC-101 is being developed as a microbicide due to its specific antiviral activity, lack of toxicity to cells and tissues, and safety in animals. Understanding potential RC-101 resistance, and how resistance to other fusion inhibitors affects RC-101 susceptibility, is critical for future development. In previous studies, we identified a mutant, R5-tropic virus that had evolved partial resistance to RC-101 during in vitro selection. Here, we report that a secondary mutation in gp41 was found to restore replicative fitness, membrane fusion, and the rate of viral entry, which were compromised by an initial mutation providing partial RC-101 resistance. Interestingly, we show that RC-101 is effective against two enfuvirtide-resistant mutants, demonstrating the clinical importance of RC-101 as a unique fusion inhibitor. These findings both expand our understanding of HIV drug-resistance to diverse peptide fusion inhibitors and emphasize the significance of compensatory gp41 mutations. © 2013 Wood et al

    A systems approach to policy evaluation

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    There is growing interest in evaluating policy implementation in ways that grapple with the complexity of the process. This article offers an example of using systems methodology to explore how the child protection policy in child contact centres has functioned in practice. Rather than just asking the traditional evaluation question “is it working?” this study sought to understand how the policy was working and how it was interpreted as it interacted with other systems, producing conflicts, local variation and emergent effects. It illustrates how the systems concepts of ‘emergence’, ‘local rationality’, ‘socio-technical systems’ and ‘feedback for learning’ can contribute new knowledge and understanding to a complex policy evaluation problem
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