164 research outputs found
Parasite and red blood counts
No full textFile contains daily parasite counts and red blood cell densities for infections with 5 genotypes of P. chabaudi which were either treated with artesunate or untreated (control). All methods as described in the paper. Please contact Laura Pollitt if any additional details are needed
data for dryad
No full textDensity data from individual mosquito dissections. For further information please contact Laura Pollitt ([email protected])
The Evolutionary Ecology of Transmission Strategies in Protozoan Parasites
No full textIn recent years there has been growing interest in applying frameworks from evolutionary ecology to understand infectious disease. It is becoming increasingly apparent that the interactions between parasites within the host environment can shape parasite phenotypes underlying infection dynamics and transmission. However, the spread of the disease will crucially depend on both within-host and between-host dynamics. Bridging these scales is challenging and for vector borne parasites, such as malaria and trypanosomes, will involve gaining a much better understanding of infection dynamics both within the host and vector. I apply evolutionary ecology frameworks including social evolution, life history theory, and phenotypic plasticity to investigate how parasite phenotypes are shaped by within-host and within-vector environments and examine the implications for in-host survival and between-host transmission. Specifically, I demonstrate that; 1. Within the host; i. In accordance with theory malaria parasites detect and respond to th
The meaning of death : evolution and ecology of apoptosis in protozoan parasites
No full textThis work was funded by the Wellcome Trust (SER: WT082234MA; http://www.wellcome.ac.uk/), the NERC (LCP: studentship), the Royal Society of London (AG: University Research Fellowship; http://royalsociety.org/), and Balliol College, University of Oxford (AG; http://www.balliol.ox.ac.uk/).The discovery that an apoptosis-like, programmed cell death (PCD) occurs in a broad range of protozoan parasites offers novel therapeutic tools to treat some of the most serious infectious diseases of humans, companion animals, wildlife, and livestock. Whilst apoptosis is an essential part of normal development, maintenance, and defence in multicellular organisms, its occurrence in unicellular parasites appears counter-intuitive and has proved highly controversial: according to the Darwinian notion of "survival of the fittest", parasites are expected to evolve strategies to maximise their proliferation, not death. The prevailing, and untested, opinion in the literature is that parasites employ apoptosis to "altruistically" self-regulate the intensity of infection in the host/vector. However, evolutionary theory tells us that at most, this can only be part of the explanation, and other non-mutually exclusive hypotheses must also be tested. Here, we explain the evolutionary concepts that can explain apoptosis in unicellular parasites, highlight the key questions, and outline the approaches required to resolve the controversy over whether parasites "commit suicide". We highlight the need for integration of proximate and functional approaches into an evolutionary framework to understand apoptosis in unicellular parasites. Understanding how, when, and why parasites employ apoptosis is central to targeting this process with interventions that are sustainable in the face of parasite evolution.Peer reviewe
Data from: Facilitation through altered resource availability in a mixed-species rodent malaria infection (Data for Figures 2 and 3)
No full textThis is the data for Figures 2 and 3, which was obtained as described in the material and methods of:Ramiro RS, Pollitt LC, Mideo N & Reece SE. Facilitation through altered resource availability in a mixed-species rodent malaria infection. Ecology LettersColumn header meanings:mouse - mouse numbertreat - treatment code (as described in the methods)method - whether parasite density data was obtained by pcr or microscopyyoelii.cumulative - cumulative P. yoelii density (per ml), after 8 days of infectionchabaudi.cumulative - cumulative P. chabaudi density (per ml), after 8 days of infectionrbc.ml.d0 - number of red blood cells (rbc) per ml of blood, on day 0retics.ml.d0 - number of young red blood cells (reticulocytes) per ml of blood, on day 0prop.retic.d0 - proportion of reticulocytes relative to total red blood cells, on day 0i.py.d0 - OD405 reading of IgG2a against crude antigen of P. yoelii, on day 0i.pc.d0 - OD405 reading of IgG2a against MSP1 of P. chabaudi AS, on day 0 Day 0 is the day of infection with P. yoelii or with a mixture of P. yoelii and P. chabaudi (see Figure 1 for details)</div
Demand-side management strategies and the residential sector: Lessons from international experience
No full textThis paper explores demand side management (DSM) strategies, including both demand response and energy efficiency policies. The aim is to uncover what features might strengthen DSM effectiveness. We first look at key features of residential energy demand and the limits to energy indicators. We then turn to historical energy intensity trends in the sector which uncover its large untapped potential. A range of barriers to energy efficiency accounting for this gap are surveyed as well as a number of potential policy responses. This reveals the necessity of a portfolio approach with bundled strategies that simultaneously impact different parts of the market, enhance the strengths of individual measures while compensating for their weaknesses through the use of complementary policies. Evidence from the international experience, in Denmark, Germany, Japan, and US is reviewed. This helps us to contrast and shed some light on the UK experience. We conclude with an emphasis on the need for a holistic underpinning approach and the indentification of a number of attributes that reinforce DSM strategies
A Connectionist and Multivariate Approach to Science Maps: Som, Clustering and Mds Applied to Library & Information Science Research.
No full textThe visualization of scientific field structures is a classic of scientometric studies. This paper presents a domain analysis of the library and information science discipline based on author co-citation analysis (ACA) and journal cocitation analysis (JCA). The techniques used for map construction are the self-organizing map (SOM) neural
algorithm, Ward’s clustering method and multidimensional
scaling (MDS). The results of this study are compared with
similar research developed by Howard White and Katherine
McCain [1]. The methodologies used allow us to confirm that
the subject domains identified in this paper are, as well,
present in our study for the corresponding period. The appearance of studies pertaining to library science reveals
the relationship of this realm with information science.
Especially significant is the presence of the management on the journal maps. From a methodological standpoint, meanwhile, we would agree with those authors who consider
MDS, the SOM and clustering as complementary methods
that provide representations of the same reality from different analytical points of view. Even so, the MDS representation is the one offering greater possibilities for the structural representation of the clusters in a set of variables
A connectionist and multivariate approach to science maps: the SOM, clustering and MDS applied to library and information science research
No full textThe visualization of scientific field structures is a classic of scientometric studies. This paper presents a domain analysis of the library and information science discipline based on author co-citation analysis (ACA) and journal cocitation analysis (JCA). The techniques used for map construction are the self-organizing map (SOM) neural algorithm, Ward’s clustering method and multidimensional scaling (MDS). The results of this study are compared with similar research developed by Howard White and Katherine McCain [1]. The methodologies used allow us to confirm that the subject domains identified in this paper are, as well,
present in our study for the corresponding period. The appearance of studies pertaining to library science reveals the relationship of this realm with information science. Especially significant is the presence of the management on the journal maps. From a methodological standpoint, meanwhile, we would agree with those authors who consider MDS, the SOM and clustering as complementary methods that provide representations of the same reality from different analytical points of view. Even so, the MDS representation is the one offering greater possibilities for the structural representation of the clusters in a set of variables
Data from: Understanding genetic variation in in vivo tolerance to artesunate: implications for treatment efficacy and resistance monitoring
No full textArtemisinin-based drugs are the front-line weapon in the treatment of human malaria cases, but there is concern that recent reports of slow clearing infections may signal developing resistance to treatment. In the absence of molecular markers for resistance, current efforts to monitor drug efficacy are based on the rate at which parasites are cleared from infections. However, some knowledge of the standing variation in parasite susceptibility is needed to identify a meaningful increase in infection half-life. Here, we show that five previously unexposed genotypes of the rodent malaria parasite Plasmodium chabaudi differ substantially in their in vivo response to treatment. Slower clearance rates were not linked to parasite virulence or growth rate, going against the suggestion that drug treatment will drive the evolution of virulence in this system. The level of variation observed here in a relatively small number of genotypes suggests existing ‘resistant’ parasites could be present in the population and therefore, increased parasite clearance rates could represent selection on pre-existing variation rather than de novo resistance events. This has implications for resistance monitoring as susceptibility may depend on evolved traits unrelated to drug exposure.Pollitt, Laura C.; Sim, Derek; Salathé, Rahel; Read, Andrew F. (2014). Data from: Understanding genetic variation in in vivo tolerance to artesunate: implications for treatment efficacy and resistance monitoring [Dataset]. Dryad. https://doi.org/10.5061/dryad.v244
Temporal patterns in immune responses to a range of microbial insults (Tenebrio molitor).
No full text8 pagesInternational audienceMuch work has elucidated the pathways and mechanisms involved in the production of insect immune effector systems. However, the temporal nature of these responses with respect to different immune insults is less well understood. This study investigated the magnitude and temporal variation in phenoloxidase and antimicrobial activity in the mealworm beetle Tenebrio molitor in response to a number of different synthetic and real immune elicitors. We found that antimicrobial activity in haemolymph increased rapidly during the first 48h after a challenge and was maintained at high levels for at least 14 days. There was no difference in the magnitude of responses to live or dead Escherichia coli or Bacillus subtilis. While peptidoglylcan also elicited a long-lasting antimicrobial response, the response to LPS was short lived. There was no long-lasting upregulation of phenoloxidase activity, suggesting that this immune effector system is not involved in the management of microbial infections over a long time scale
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