126 research outputs found

    Genetics and genomics converge on the human blood fluke

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    A genetic map of the human infective blood fluke Schistosoma mansoni offers new approaches for research on this important parasitic worm

    Analysis of putative resistance gene loci in UK field populations of Haemonchus contortus after six years of macrocyclic lactone use

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    Sheep farmers in the UK rely on strategic anthelmintic use to treat and control gastrointestinal roundworms in their flocks. However, resistance to these drugs is now widespread and threatens the sustainability of sheep production. The mechanisms underlying resistance to the most commonly used class, the macrocyclic lactones, are not known and sensitive diagnostic tools based on molecular markers are not currently available. This prohibits accurate surveillance of resistance or assessment of strategies aimed at controlling its spread. In this study, we examined four UK field populations of Haemonchus contortus, differing in macrocyclic lactone treatment history, for evidence of selection at ‘candidate gene’ loci identified as determining macrocyclic lactone resistance in previously published research. Individual worms were genotyped at Hc-lgc-37, Hc-glc-5, Hc-avr-14 and Hc-dyf-7, and four microsatellite loci. High levels of polymorphism were identified at the first three candidate gene loci with remarkably little polymorphism at Hc-dyf-7. While some between-population comparisons of individual farms with and without long-term macrocyclic lactone use identified statistically significant differences in allele frequency and/or fixation index at the Hc-lgc-37, Hc-glc-5 or Hc-avr-14 loci, we found no consistent evidence of selection in other equivalent comparisons. While it is possible that different mechanisms are important in different populations or that resistance may be conferred by small changes at multiple loci, our findings suggest that these are unlikely to be major loci conferring macrocyclic lactone resistance on UK farms or suitable for diagnostic marker development. More powerful approaches, using genome-wide or whole genome sequencing, may be required to define macrocyclic lactone resistance loci in such genetically variable populations

    Genetic exchange in <i>Trypanosoma brucei</i>: evidence for mating prior to metacyclic stage development

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    It is well established that genetic exchange occurs between Trypanosoma brucei parasites when two stocks are used to infect tsetse flies under laboratory conditions and a number of such crosses have been undertaken. Both cross and self-fertilisation can take place and, with the products of mating being the equivalent of F1 progeny in a Mendelian system and. Recently, analysis of a large collection of independent progeny using a series of polymorphic micro and minisatellite markers, has formally demonstrated that the allelic segregation at loci on each of the 11-megabase chromosomes conforms to ratios predicted for a classical diploid genetic system involving meiosis as well as independent assortment of markers on different chromosomes. Further extensive analysis of these F1 progeny, using a large panel of micro and minisatellite markers, has led to the construction of a genetic map of one parasite stock A. MacLeod, A. Tweedie and S. McLellan et al., The genetic map of Trypanosoma brucei, Nucleic Acids Res 33 (2005), pp. 6688–6693. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (10)

    Allelic segregation and independent assortment in <i>T. brucei</i> crosses: proof that the genetic system is Mendelian and involves meiosis

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    The genetic system on Trypanosoma brucei has been analysed by generating large numbers of independent progeny clones from two crosses, one between two cloned isolates of Trypanosoma brucei brucei and one between cloned isolates of T. b. brucei and Trypanosoma brucei gambiense, Type 2. Micro and minisatellite markers (located on each of the 11 megabase housekeeping chromosomes) were identified, that are heterozygous in one or more of the parental strains and the segregation of alleles at each locus was then determined in each of the progeny clones. The results unequivocally show that alleles segregate in the predicted ratios and that alleles at loci on different chromosomes segregate independently. These data provide statistically robust proof that the genetic system is Mendelian and that meiosis occurs. Segregation distortion is observed with the minisatellite locus located on chromosome I of T. b. gambiense Type 2 and neighboring markers, but analysis of markers further along this chromosome did not show distortion leading to the conclusion that this is due to selection acting on one part of this chromosome. The results obtained are discussed in relation to previously proposed models of mating and support the occurrence of meiosis to form haploid gametes that then fuse to form the diploid progeny in a single round of mating

    Successful Downstaging of High Rectal and Recto-Sigmoid Cancer by Neo-Adjuvant Chemo-Radiotherapy

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    © 2008 Libertas Academica Ltd. All rights reserved.Purpose: The benefit of neoadjuvant therapy for tumours above the peritoneal reflection is not clear. The purpose of this study is to demonstrate the feasibility and downstaging of treating locally advanced tumours from high rectum to distal sigmoid with preoperative chemoradiotherapy (CRT).Methods and Materials: Seventeen patients with high rectal, rectosigmoid or distal sigmoid tumours above the peritoneal reflection received neoadjuvant CRT, selected on MRI findings indicating T4 disease or threatened circumferential resection margin. All patients were administered neoadjuvant chemotherapy, with Oxaliplatin or Mitomycin C and a Fluoropyrimidine. The pelvis received long-course CT-planned conformal RT, 45 Gy in 25 fractions, with a boost of 5.4–9 Gy in 3–5 fractions. Thirteen patients were treated with concomitant oral or intravenous Fluoropyrimidine chemotherapy.Results: Median follow-up was 37 months. Overall survival was 82.35% (95% Confidence Interval (CI) 54.7–93.9) and disease free survival 81.25% (95% CI 52.5–93.5). Only 1 patient suffered loco-regional relapse. Chemotherapy regimens were well tolerated, though some patients required dose reductions. Nine patients (52.9%) lowered pathologic disease AJCC stage, i.e. ‘downstaged’. Six patients (35.3%) achieved complete pathological response. Clear margins were attained in all but 1 patient. Three patients were converted from cT4 to ypT3. No patient required a gap during CRT. One patient suffered a grade III acute toxicity, but no grade IV (RTOG). There were 3 grade III and 3 grade IV late toxicities (LENT-SOMA).Conclusions: Locally advanced high rectal and recto-sigmoid tumours may be treated with pre-operative CRT with acceptable toxicity, impressive down-staging, and clear surgical margins

    Bring your own heritage: final project report.

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    Public libraries have traditionally played a role in the acquisition and curation of local studies collections, and cultural heritage is recognised as a core area of activity for libraries aiming to increase patron numbers (Danish Agency for Libraries and Media, 2010). Developments in digital technologies present libraries with new opportunities to enhance this area of strength and expertise. For example, crowdsourcing, gaming and laser scanning could be used to increase engagement and to enable more people to both access and contribute to these collections (Laing and Scott, 2011; Nicholson, 2013; Czarnecki, 2010). Libraries are increasingly becoming spaces where knowledge is created and shared, and many are making use of collaborative and social technologies to encourage this (Paulus, 2011). Our project was conducted in partnership with Moray Council in Elgin, in the Northeast of Scotland. It has a rich history dating back to the 12th century - but, like many areas, it is facing challenges. The library service in the local authority area of Moray has been threatened with cuts, with four local branches earmarked for closure (BBC, 2013). The main aim of this research was to investigate the opportunities and challenges for libraries to develop their role as facilitators of community heritage curation through the development of IT utilities, such as laser scanning and gaming

    Molecular surveillance of Theileria parasites of livestock in Oman

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    Background: Theileriosis is one of the most prevalent infectious diseases of livestock in the Arabian Peninsula, and causes high rates of mortality and morbidity in sheep and cattle. However, there is a paucity of information on the distribution of Theileria spp. over the whole region and their impact on different hosts. The present study carried out a country-wide molecular survey for Theileria spp. of livestock in Oman across four governorates. The aim of the survey was to define the prevalence of Theileria spp. in cattle, sheep and goats, highlight risk factors for infection and identify the main tick species involved in parasite transmission. Material and methods: A total of 2020 animals were examined in the survey consisting of sheep [n = 592], goats [n = 981] and cattle [n = 447]. All three species were raised and co-grazed on the same farms. Theileria parasites were detected using PCR-RFLP and RLB of the 18S rRNA gene. Cloning and sequencing of the 18S rRNA was carried out on 11 T. lestoquardi isolates from Ash-Sharqiyah, and Ad-Dhahira governorates, and phylogenetic relationships were inferred using additional sequences of T. lestoquardi, T. annulata and T. ovis available in GenBank. Results: Theileria spp. prevalence was 72.3%, 36.7% and 2.7% among cattle, sheep and goats, respectively. Strong similarity in results was obtained using RLB and PCR-RFLP for detection of Theileria spp. however, RLB detected a higher rate of mixed infection than PCR-RFPL (P &lt; 0.001). Theileria annulata was the only parasite detected in cattle, while sheep and goats carried T. ovis, T. lestoquardi and T. annulata as well as Theileria spp. OT1. Of the four Theileria spp. detected in small ruminants, overall T. ovis was most prevalent (sheep [33.4%], goats [2.0%]), whereas T. lestoquardi was less prevalent (sheep [22.0%], goats [0.5%]). A large proportion of infected sheep (19%) carried mixed infection of T. ovis and T. lestoquardi. However, single T. lestoquardi infections (3.0%) were less prevalent than T. ovis infections (14.5%). Risk of Theileria spp. infection was significantly higher for exotic breeds, relative to native breeds, of cattle (p = 0.00002) and sheep (p = 0.005). Phylogenetic analysis placed T. lestoquardi in Oman in the same clade as other T. lestoquardi strains isolated from the same regional area (Iraq and Iran). The main tick species, identified on the examined animals, Hyalomma anatolicum, was widely distributed and was found in all of the surveyed governorates. Conclusion: Theileria spp. are widespread in Oman with variable prevalence detected in different regions. Two economically important hosts, cattle and sheep are at high risk from virulent T. annulata and T. lestoquardi, respectively. The survey indicates extensive exposure to ticks and transmission of infection that has a significant economic impact. The higher prevalence of T. lestoquardi as mixed rather than single infection requires further investigation

    Human and animal Trypanosomes in Côte d'Ivoire form a single breeding population.

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    BACKGROUND: Trypanosoma brucei is the causative agent of African Sleeping Sickness in humans and contributes to the related veterinary disease, Nagana. T. brucei is segregated into three subspecies based on host specificity, geography and pathology. T. b. brucei is limited to animals (excluding some primates) throughout sub-Saharan Africa and is non-infective to humans due to trypanolytic factors found in human serum. T. b. gambiense and T. b. rhodesiense are human infective sub-species. T. b. gambiense is the more prevalent human, causing over 97% of human cases. Study of T. b. gambiense is complicated in that there are two distinct groups delineated by genetics and phenotype. The relationships between the two groups and local T. b. brucei are unclear and may have a bearing on the evolution of the human infectivity traits. METHODOLOGY/PRINCIPAL FINDINGS: A collection of sympatric T. brucei isolates from Côte d'Ivoire, consisting of T. b. brucei and both groups of T. b. gambiense have previously been categorized by isoenzymes, RFLPs and Blood Incubation Infectivity Tests. These samples were further characterized using the group 1 specific marker, TgSGP, and seven microsatellites. The relationships between the T. b. brucei and T. b. gambiense isolates were determined using principal components analysis, neighbor-joining phylogenetics, STRUCTURE, FST, Hardy-Weinberg equilibrium and linkage disequilibrium. CONCLUSIONS/SIGNIFICANCE: Group 1 T. b. gambiense form a clonal genetic group, distinct from group 2 and T. b. brucei, whereas group 2 T. b. gambiense are genetically indistinguishable from local T. b. brucei. There is strong evidence for mating within and between group 2 T. b. gambiense and T. b. brucei. We found no evidence to support the hypothesis that group 2 T. b. gambiense are hybrids of group 1 and T. b. brucei, suggesting that human infectivity has evolved independently in groups 1 and 2 T. b. gambiense

    (Re)presenting heritage: laser scanning and 3D visualisations for cultural resilience and community engagement.

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    Cultural heritage is increasingly being viewed as an economic asset for geographic areas who aim to capitalise in the surge in interest in local history and heritage tourism from members of the public. Digital technologies have developed that facilitate new forms of engagement with heritage and allow local areas to showcase their history, potentially broadening interest to a wider audience, thus acting as a driver for cultural and economic resilience. The research presented in this paper explores this through interdisciplinary research utilising laser scanning and visualisation in combination with social research in Elgin. 3D data capture technologies were used to develop and test 3D data visualisations and protocols through which the urban built heritage can be digitally recorded. The main focus of this paper surrounds the application and perceptions of these technologies. Findings suggest that the primary driver for cultural heritage developments was economic (with an emphasis on tourism) but further benefits and key factors of community engagement, social learning and cultural resilience were also reported. Stakeholder engagement and partnership working, in particular, were identified as critical factors of success. The findings from the community engagement events demonstrate that laser scanning and visualisation provide a novel and engaging mechanism for co-producing heritage assets. There is a high level of public interest in such technologies and users who engaged with these models reported that they gained new perspectives (including spatial and temporal perspectives) on the built heritage of the area
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