A Surface Antigen from Trypanosoma congolense

Using monoclonal antibodies, a surface membrane antigen was identified on T. congolense procyclic cells

Spatial variation in species composition of Saprolegnia, a parasitic oomycete of amphibian eggs, in Scotland

This document is the Accepted Manuscript version of a published work that appeared in final form in Herpetological Journal. To access the final edited and published work see http://www.thebhs.org/index.php?option=com_docman&Itemid=42.Parasitic water moulds in the genus Saprolegnia cause mortality of amphibian embryos and reduced size at metamorphosis, leading to increased adult mortality. Most studies of virulence have focused on only a single Saprolegnia species, but the Saprolegnia species associated with amphibian eggs and their distributions are not well known. This study aimed to investigate the distribution of amphibian-associated water moulds in Scotland. In particular, we asked the questions: i) Does Saprolegnia species composition vary between sites?; and ii) Is presence of Saprolegnia related to environmental parameters? Common frog (Rana temporaria) eggs with evidence of Saprolegnia infection were sampled from ten sites, cultured, and the 28S region of the rDNA array sequenced. Thirteen samples isolated from four sites were identified as members of the Saprolegniaceae and the ITS region of these samples were subsequently sequenced to further resolve species identification. Four species of Saprolegnia were found in total, with one or two species of Saprolegnia present in each of four sites. S. diclina was the most common species identified and was found at three of the four sites. Acidity was significantly lower and altitude significantly higher at sites where Saprolegniaceae were present. Therefore, R. temporaria eggs in different pools are subject to infection by different, and in some instances more than one, species of Saprolegnia. Overall, our findings suggest that future studies of virulence need to consider the effect of multiple Saprolegnia species within a site as well as the population of origin of the amphibian hostFieldwork was supported by grants from the Royal Geographic Society, the Glasgow Natural History Society and the Scottish Mountaineering Trust. This study was supported by PhD CASE studentship funding from the Biotechnology and Biological Sciences Research Council, in partnership with the Royal Zoological Society of Scotland

Experimental evidence for opposing effects of high deer density on tick-borne pathogen prevalence and hazard

BACKGROUND: Identifying the mechanisms driving disease risk is challenging for multi-host pathogens, such as Borrelia burgdorferi sensu lato (s.l.), the tick-borne bacteria causing Lyme disease. Deer are tick reproduction hosts but do not transmit B. burgdorferi s.l., whereas rodents and birds are competent transmission hosts. Here, we use a long-term deer exclosure experiment to test three mechanisms for how high deer density might shape B. burgdorferi s.l. prevalence in ticks: increased prevalence due to higher larval tick densities facilitating high transmission on rodents (M1); alternatively, reduced B. burgdorferi s.l. prevalence because more larval ticks feed on deer rather than transmission-competent rodents (dilution effect) (M2), potentially due to ecological cascades, whereby higher deer grazing pressure shortens vegetation which decreases rodent abundance thus reducing transmission (M3). METHODS: In a large enclosure where red deer stags were kept at high density (35.5 deer km(−2)), we used an experimental design consisting of eight plots of 0.23 ha, four of which were fenced to simulate the absence of deer and four that were accessible to deer. In each plot we measured the density of questing nymphs and nymphal infection prevalence in spring, summer and autumn, and quantified vegetation height and density, and small mammal abundance. RESULTS: Prevalence tended to be lower, though not conclusively so, in high deer density plots compared to exclosures (predicted prevalence of 1.0% vs 2.2%), suggesting that the dilution and cascade mechanisms might outweigh the increased opportunities for transmission mechanism. Presence of deer at high density led to shorter vegetation and fewer rodents, consistent with an ecological cascade. However, Lyme disease hazard (density of infected I. ricinus nymphs) was five times higher in high deer density plots due to tick density being 18 times higher. CONCLUSIONS: High densities of tick reproduction hosts such as deer can drive up vector-borne disease hazard, despite the potential to simultaneously reduce pathogen prevalence. This has implications for environmental pathogen management and for deer management, although the impact of intermediate deer densities now needs testing. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13071-021-05000-0

Habitat preferences, foraging behaviour and bycatch risk among breeding sooty shearwaters Ardenna grisea in the Southwest Atlantic.

Pelagic seabirds are important components of many marine ecosystems. The most abundant species are medium/small sized petrels (<1100 g), yet the sub-mesoscale (<10 km) distribution, habitat use and foraging behaviour of this group are not well understood. Sooty shearwaters Ardenna grisea are among the world’s most numerous pelagic seabirds. The majority inhabit the Pacific, where they have declined, partly due to bycatch and other anthropogenic impacts, but they are increasing in the Atlantic. To evaluate the sub-mesoscale habitat preferences (i.e. the disproportionality between habitat use and availability), diving behaviour and bycatch risk of Atlantic breeders, we tracked sooty shearwaters from the Falkland Islands during late incubation and early chick-rearing with GPS loggers (n = 20), geolocators (n = 10) and time-depth recorders (n = 10). These birds foraged exclusively in neritic and shelf-break waters, principally over the Burdwood Bank, ~350 km from their colony. Like New Zealand breeders, they dived mostly during daylight, especially at dawn and dusk, consistent with the exploitation of vertically migrating prey. However, Falkland birds made shorter foraging trips, shallower dives, and did not forage in oceanic waters. Their overlap with fisheries was low, and they foraged at shallower depths than those targeted by trawlers, the most frequent fishing vessels encountered, indicating that bycatch risk was low during late incubation/early chick-rearing. Although our results should be treated with caution, they indicate that Atlantic and Pacific sooty shearwaters may experience markedly differing pressures at sea. Comparative study between these populations, e.g. combining biologging and demography, is therefore warranted

Blood meal analysis of tsetse flies (Glossina pallidipes: Glossinidae) reveals higher host fidelity on wild compared with domestic hosts

Background: Changes in climate and land use can alter risk of transmission of parasites between domestic hosts and wildlife, particularly when mediated by vectors that can travel between populations. Here we focused on tsetse flies (genus Glossina), the cyclical vectors for both Human African Trypanosomiasis (HAT) and Animal African Trypanosomiasis (AAT). The aims of this study were to investigate three issues related to G. palldipes from Kenya: 1) the diversity of vertebrate hosts that flies fed on; 2) whether host feeding patterns varied in relation to type of hosts, tsetse feeding behaviour, site or tsetse age and sex; and 3) if there was a relationship between trypanosome detection and host feeding behaviours or host types. Methods: Sources of blood meals of Glossina pallidipes were identified by sequencing of the mitochondrial cytochrome b gene and analyzed in relationship with previously determined trypanosome detection in the same flies. Results: In an area dominated by wildlife but with seasonal presence of livestock (Nguruman), 98% of tsetse fed on single wild host species, whereas in an area including a mixture of resident domesticated animals, humans and wildlife (Shimba Hills), 52% of flies fed on more than one host species. Multiple Correspondence Analysis revealed strong correlations between feeding pattern, host type and site but these were resolved along a different dimension than trypanosome status, sex and age of the flies. Conclusions: Our results suggest that individual G. pallidipes in interface areas may show higher feeding success on wild hosts when available but often feed on both wild and domesticated hosts. This illustrates the importance of G. pallidipes as a vector connecting the sylvatic and domestic cycles of African trypanosomes

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SNP calls for chromosome 5 from bulked segregant analysis. F1s were generated from crosses between a self-incompatible and a self-compatible parent of Arabidopsis lyrata, sampled from the Great Lakes region of Eastern North America, which were then crossed amongst themselves to create F2s. Pools were created from: 1) 10 individuals that were phenotypically self-incompatible; and 2) 10 individuals that were phenotypically self-compatible. Three lanes of separate runs (two 150 bp and one 100 bp paired-end read run) were sequenced on an Illumina GAII instrument for each pool. The Illumina quality-filtered reads were mapped against the A. lyrata reference genome sequence MN47 (Hu et al. 2011) using GenomeMapper (Schneeberger et al. 2009), allowing for up to 10% mismatches/gaps relative to the read length. All alternative alleles relative to the reference base with a minimum frequency within each pool of 10% and a score of at least 25 were called by SHORE, as described (Ossowski et al. 2008). SNP calls (in genes only) were made using SHORE and compared for the two pools against the MN47 reference and for a reference genome constructed from two self-compatible individuals (AL4). These individuals were created by hybridisation between individuals sampled from the same population used for the self-compatible parent of the pools with the MN47 reference strain. The genomic sequence thus was determined by subtraction from the MN47 reference. The data file shows the SNP calls, % of reads with the variant and read coverage for that position. See readme file for complete details. References Hu TT, Pattyn P, Bakker EG, et al. (2011) The Arabidopsis lyrata genome sequence and the basis of rapid genome size change. Nature Genetics 43, 476-481. doi: 10.1038/ng.807 Ossowski S, Schneeberger K, Clark RM, et al. (2008) Sequencing of natural strains of Arabidopsis thaliana with short reads. Genome Research 18, 2024-2033. 10.1101/gr.080200.108 Schneeberger K, Hagmann J, Ossowski S, et al. (2009) Simultaneous alignment of short reads against multiple genomes. Genome Biology 10, 1-12. 10.1186/gb-2009-10-9-r9

R-gene variation across Arabidopsis lyrata subspecies: effects of population structure, selection and mating system.

BACKGROUND: Examining allelic variation of R-genes in closely related perennial species of Arabidopsis thaliana is critical to understanding how population structure and ecology interact with selection to shape the evolution of innate immunity in plants. We finely sampled natural populations of Arabidopsis lyrata from the Great Lakes region of North America (A. l. lyrata) and broadly sampled six European countries (A. l. petraea) to investigate allelic variation of two R-genes (RPM1 and WRR4) and neutral genetic markers (Restriction Associated DNA sequences and microsatellites) in relation to mating system, phylogeographic structure and subspecies divergence. RESULTS: Fine-scale sampling of populations revealed strong effects of mating system and population structure on patterns of polymorphism for both neutral loci and R-genes, with no strong evidence for selection. Broad geographic sampling revealed evidence of balancing selection maintaining polymorphism in R-genes, with elevated heterozygosity and diversity compared to neutral expectations and sharing of alleles among diverged subspecies. Codon-based tests detected both positive and purifying selection for both R-genes, as commonly found for animal immune genes. CONCLUSIONS: Our results highlight that combining fine and broad-scale sampling strategies can reveal the multiple factors influencing polymorphism and divergence at potentially adaptive genes such as R-genes