Bibliografie tematiche / Host-Parasite systems

Indice

Articoli di riviste
Tesi
Libri
Capitoli di libri
Atti di convegni
Rapporti di organizzazioni

Letteratura scientifica selezionata sul tema "Host-Parasite systems"

Autore: Grafiati

Pubblicato: 11 gennaio 2025

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili

Scegli il tipo di fonte:

Consulta la lista di attuali articoli, libri, tesi, atti di convegni e altre fonti scientifiche attinenti al tema "Host-Parasite systems".

Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.

Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.

Articoli di riviste sul tema "Host-Parasite systems"

Boots, Michael, e Akira Sasaki. "Parasite‐Driven Extinction in Spatially Explicit Host‐Parasite Systems". American Naturalist 159, n. 6 (giugno 2002): 706–13. http://dx.doi.org/10.1086/339996.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Kaltz, Oliver, e Jacqui A. Shykoff. "Local adaptation in host–parasite systems". Heredity 81, n. 4 (ottobre 1998): 361–70. http://dx.doi.org/10.1046/j.1365-2540.1998.00435.x.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Swann, Justine, Neema Jamshidi, Nathan E. Lewis e Elizabeth A. Winzeler. "Systems analysis of host-parasite interactions". Wiley Interdisciplinary Reviews: Systems Biology and Medicine 7, n. 6 (26 agosto 2015): 381–400. http://dx.doi.org/10.1002/wsbm.1311.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Dallas, Tad, Shan Huang, Charles Nunn, Andrew W. Park e John M. Drake. "Estimating parasite host range". Proceedings of the Royal Society B: Biological Sciences 284, n. 1861 (30 agosto 2017): 20171250. http://dx.doi.org/10.1098/rspb.2017.1250.

Testo completo

Abstract (sommario):

Estimating the number of host species that a parasite can infect (i.e. host range) provides key insights into the evolution of host specialism and is a central concept in disease ecology. Host range is rarely estimated in real systems, however, because variation in species relative abundance and the detection of rare species makes it challenging to confidently estimate host range. We applied a non-parametric richness indicator to estimate host range in simulated and empirical data, allowing us to assess the influence of sampling heterogeneity and data completeness. After validating our method on simulated data, we estimated parasite host range for a sparsely sampled global parasite occurrence database (Global Mammal Parasite Database) and a repeatedly sampled set of parasites of small mammals from New Mexico (Sevilleta Long Term Ecological Research Program). Estimation accuracy varied strongly with parasite taxonomy, number of parasite occurrence records, and the shape of host species-abundance distribution (i.e. the dominance and rareness of species in the host community). Our findings suggest that between 20% and 40% of parasite host ranges are currently unknown, highlighting a major gap in our understanding of parasite specificity, host–parasite network structure, and parasite burdens.

Gli stili APA, Harvard, Vancouver, ISO e altri

Turner, Wendy C., Pauline L. Kamath, Henriette van Heerden, Yen-Hua Huang, Zoe R. Barandongo, Spencer A. Bruce e Kyrre Kausrud. "The roles of environmental variation and parasite survival in virulence–transmission relationships". Royal Society Open Science 8, n. 6 (giugno 2021): 210088. http://dx.doi.org/10.1098/rsos.210088.

Testo completo

Abstract (sommario):

Disease outbreaks are a consequence of interactions among the three components of a host–parasite system: the infectious agent, the host and the environment. While virulence and transmission are widely investigated, most studies of parasite life-history trade-offs are conducted with theoretical models or tractable experimental systems where transmission is standardized and the environment controlled. Yet, biotic and abiotic environmental factors can strongly affect disease dynamics, and ultimately, host–parasite coevolution. Here, we review research on how environmental context alters virulence–transmission relationships, focusing on the off-host portion of the parasite life cycle, and how variation in parasite survival affects the evolution of virulence and transmission. We review three inter-related ‘approaches’ that have dominated the study of the evolution of virulence and transmission for different host–parasite systems: (i) evolutionary trade-off theory, (ii) parasite local adaptation and (iii) parasite phylodynamics. These approaches consider the role of the environment in virulence and transmission evolution from different angles, which entail different advantages and potential biases. We suggest improvements to how to investigate virulence–transmission relationships, through conceptual and methodological developments and taking environmental context into consideration. By combining developments in life-history evolution, phylogenetics, adaptive dynamics and comparative genomics, we can improve our understanding of virulence–transmission relationships across a diversity of host–parasite systems that have eluded experimental study of parasite life history.

Gli stili APA, Harvard, Vancouver, ISO e altri

McDevitt-Galles, Travis, Wynne E. Moss, Dana M. Calhoun e Pieter T. J. Johnson. "Phenological synchrony shapes pathology in host–parasite systems". Proceedings of the Royal Society B: Biological Sciences 287, n. 1919 (22 gennaio 2020): 20192597. http://dx.doi.org/10.1098/rspb.2019.2597.

Testo completo

Abstract (sommario):

A key challenge surrounding ongoing climate shifts is to identify how they alter species interactions, including those between hosts and parasites. Because transmission often occurs during critical time windows, shifts in the phenology of either taxa can alter the likelihood of interaction or the resulting pathology. We quantified how phenological synchrony between vulnerable stages of an amphibian host ( Pseudacris regilla ) and infection by a pathogenic trematode ( Ribeiroia ondatrae ) determined infection prevalence, parasite load and host pathology. By tracking hosts and parasite infection throughout development between low- and high-elevation regions (San Francisco Bay Area and the Southern Cascades (Mt Lassen)), we found that when phenological synchrony was high (Bay Area), each established parasite incurred a 33% higher probability of causing severe limb malformations relative to areas with less synchrony (Mt Lassen). As a result, hosts in the Bay Area had up to a 50% higher risk of pathology even while controlling for the mean infection load. Our results indicate that host–parasite interactions and the resulting pathology were the joint product of infection load and phenological synchrony, highlighting the sensitivity of disease outcomes to forecasted shifts in climate.

Gli stili APA, Harvard, Vancouver, ISO e altri

Horn, Collin J., e Lien T. Luong. "Proximity to parasites reduces host fitness independent of infection in a Drosophila–Macrocheles system". Parasitology 145, n. 12 (13 marzo 2018): 1564–69. http://dx.doi.org/10.1017/s0031182018000379.

Testo completo

Abstract (sommario):

AbstractParasites are known to have direct negative effects on host fitness; however, the indirect effects of parasitism on host fitness sans infection are less well understood. Hosts undergo behavioural and physiological changes when in proximity to parasites. Yet, there is little experimental evidence showing that these changes lead to long-term decreases in host fitness. We aimed to determine if parasite exposure affects host fitness independent of contact, because current approaches to parasite ecology may underestimate the effect of parasites on host populations. We assayed the longevity and reproductive output of Drosophila nigrospiracula exposed or not exposed to ectoparasitic Macrocheles subbadius. In order to preclude contact and infection, mites and flies were permanently separated with a mesh screen. Exposed flies had shorter lives and lower fecundity relative to unexposed flies. Recent work in parasite ecology has argued that parasite–host systems show similar processes as predator–prey systems. Our findings mirror the non-consumptive effects observed in predator–prey systems, in which prey species suffer reduced fitness even if they never come into direct contact with predators. Our results support the perspective that there are analogous effects in parasite–host systems, and suggest new directions for research in both parasite ecology and the ecology of fear.

Gli stili APA, Harvard, Vancouver, ISO e altri

Hovestadt, Thomas, Jeremy A. Thomas, Oliver Mitesser e Karsten Schönrogge. "Multiple host use and the dynamics of host switching in host–parasite systems". Insect Conservation and Diversity 12, n. 6 (14 agosto 2019): 511–22. http://dx.doi.org/10.1111/icad.12374.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Medley, G. F. "Which comes first in host-parasite systems: Density dependence or parasite distribution?" Parasitology Today 8, n. 10 (ottobre 1992): 321–22. http://dx.doi.org/10.1016/0169-4758(92)90061-6.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Adda, P., J. L. Dimi, A. Iggidir, J. C. Kamgang, G. Sallet e J. J. Tewa. "General models of host-parasite systems. Global analysis". Discrete & Continuous Dynamical Systems - B 8, n. 1 (2007): 1–17. http://dx.doi.org/10.3934/dcdsb.2007.8.1.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Più fonti

Tesi sul tema "Host-Parasite systems"

Keeling, Matthew James. "The ecology and evolution of spatial host-parasite systems". Thesis, University of Warwick, 1995. http://wrap.warwick.ac.uk/30/.

Testo completo

Abstract (sommario):

All ecological and epidemiological systems are embedded in space and composed of individuals; these facts often have a profound effect on the dynamics and means many tools and definitions require reformulation. Modelling has always been about taking highly complex dynamical systems, such as the natural environment, and attempting to simplify them to a leve that can be conceptualised, in the process losing all the features that are not understood or not anticipated. The individual based spatial models which form the basis of this work start from the simple rules for individuals and build up to a complex system, allowing new, unexpected phenomenon to arise naturally. The local interactions in spatial models lead to short scale correlations and self-induced spatial heterogeneity as the small fluctuations of environmental noise are amplified into macro-scale patterns. These spatial patterns can lead to ephemeral refuges for hosts from where they can disperse stabilising the dynamics. After discussing the importance and variety of host-parasite interactions several techniques to be used in this work are developed and explained on simple examples. Chapters III and IV introduce a caricature host-pathogen model and how how this deviates from the standard mean field theory approximations. Attention is then turned to host-parasitoid systems and the spatially extended Nicholson-Bailey equations; probems with this coupled map lattice are highlighted and an alternative artificial ecology is formulated. Remaining with the Nicholson-Bailey equations these are forced to be integer based by utilising stochastic events, this greatly stabilises the dynamics hence the method was applied to the persistence of measles epidemics in small populations (=500000). Chapter VII demonstrates how the inclusion of space enhances the effects of parasitism in increasing the evolutionary advantage of sexual hosts over asexual ones. Finally general techniques are developed to implicitly model the effects of spatial correlations and stochastic individual based interactions.

Gli stili APA, Harvard, Vancouver, ISO e altri

Crosswaite, Matthew John. "Parasite distribution and specificity in anuran host complexes". Thesis, Queen Mary, University of London, 1994. http://qmro.qmul.ac.uk/xmlui/handle/123456789/26224.

Testo completo

Abstract (sommario):

This study was based on the parasite fauna of three anuran systems. In two of the systems; the spadefoot toads, Scaphiopus bombifrons and S. multiplicatus and the fire and yellow-bellied toads, Bombina bombina and B.variegata, inter-species hybridisation occurs. In the third system an autopolyploid species complex involves the Gray treefrogs, Hyla chrysoscelis and H.versicolor. The status of the Scaphiopus hybrid zone in Arizona was re-assessed by cellulose-acetate gel electrophoresis. Genotypic frequencies were comparable to those previously documented, indicating that a region of 'balanced introgression' may exist. Specimens were collected in areas of host sympatry and the distribution of helminths within hosts of different genetic constitution investigated. From extensive surveys of all three systems, parasite frequency distributions were typically aggregated with no evidence of any change in host genetic predisposition to infection. In addition, the surveys have documented a number of new host and/or parasite locality records for each system. Of particular interest was the discovery of the digenean Clinostomum complanatum in a desert environment, an introduction related to human management of the ecosystem. Particular reference was made to the specificity of the polystomatid monogeneans, Polystoma nearcticum infecting members of the H.chrysoscelis- H.versicolor complex and Neodiplorchis scaphiopodis infecting S.bombifrons and S.multiplicatus. For Polystoma, worms from H.chlysoscelis and H.versicolor could not be separated by morphology, which was supported by preliminary crossinfections. This suggests that P.nearcticum infects both members of this complex. For Neodiplorchis, morphological similarity was confirmed by cross-infections which revealed that N.scaphiopodis can reach sexual maturity and produce fully developed larvae in heterospecific hosts. The neotenic development of P. nearcticum and the initial post-oncomiracidial stages of N.scaphiopodis were documented. Furthermore, certain aspects of transmission dynamics were examined by the experimental infection of H. versicolor tadpoles with P. nearcticum.

Gli stili APA, Harvard, Vancouver, ISO e altri

Gubbins, S. "Dynamics and control of host-parasite systems in heterogeneous and disturbed environments". Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599772.

Testo completo

Abstract (sommario):

Using a combination of mathematical analysis, model fitting and parameter estimation, this thesis examines the dynamics and control of host-parasite systems in heterogeneous and disturbed environments. The first chapter introduces and tests models for the population dynamics of Sclerotinia minor, an economically important fungal plant parasite, and the fungal hyperparasite Sporidesmium sclerotivorum in a closed system from which any host of S. minor is excluded. Model structures are identified that reflect experimental data rather than models that are simply mathematical abstractions. Various elaborations of this simple model are discussed in the next chapter and, specifically, the effect of a latent period of infection and the influence of differentiating between primary and secondary infections are considered. In the following chapter, models are developed in which the dynamics of a host crop (lettuce) of S. minor are included. Various mechanisms that contribute to the observed persistence of the parasite are examined and, in particular, the roles played by discontinuities due to planting and harvesting of the lettuce crop, spatial heterogeneity and changes in environmental conditions are considered. Although the models discussed in the first three chapters are developed with close reference to the S. minor-S. sclerotivorum system, they are of broad applicability. In the remaining largely theoretical chapters, the population dynamics of the models are analysed, paying particular attention to thresholds for invasion and persistence. The persistence of host-parasite interactions in disturbed environments (where the host is not continuously present or does not continuously reproduce) is considered first. In the penultimate chapter, thresholds for invasion in plant-parasite systems are derived. These systems are characterised by dual sources of inoculum (primary and secondary infection) and a host response to infection load. Finally, the simple model fitted to the S. minor-S. sclerotivorum data is used to examine the effects of heterogeneous mixing on invasion and persistence.

Gli stili APA, Harvard, Vancouver, ISO e altri

Miller, Martin Roy. "Theoretical models for the evolution and ecological dynamics of host-parasite systems". Thesis, University of Sheffield, 2006. http://etheses.whiterose.ac.uk/14903/.

Testo completo

Abstract (sommario):

Natural organisms are infected by many different parasites, and as a consequence, hosts have evolved a wide range of defences to cope with them. Resistance may be conferred through mechanisms that reduce susceptibility to infection ('avoidance') or increase the rate of clearance ('recovery'). Other forms of resistance reduce the deleterious effects of infection ('tolerance'), or inhibit the parasite's growth ('control'). In addition to these innate forms, hosts may also benefit from immunological memory ('acquired immunity'). The evolution of resistance is expected to be costly in terms of other life history traits. In the presence of such 'trade-offs', the host population may evolve towards an evolutionarily stable strategy (ESS) that balances the costs and benefits of resistance. Another possibility is that a process of evolutionary branching occurs, leading to polymorphism of distinct strategies. Parasites also show adaptation to their hosts and have generally not evolved to be avirulent. Again, this is the result of trade-offs between virulence and other aspects of life history. Often, a higher transmission rate is attained at the cost of increased virulence. This thesis uses a mathematical modelling approach to examine hostparasite interactions. The first part considers the evolutionary dynamics of quantitative host resistance and parasite traits, employing fitness expressions constructed using the techniques of adaptive dynamics. The second part examines the population dynamics of host-parasite interactions; in particular, how different assumptions about the nature of the transmission process may affect the dynamics.

Gli stili APA, Harvard, Vancouver, ISO e altri

Keppel, Michelle [Verfasser], e Bernd [Akademischer Betreuer] Sures. "Mutual adaptation in differently evolved host-parasite systems / Michelle Keppel ; Betreuer: Bernd Sures". Duisburg, 2016. http://d-nb.info/1116941791/34.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Rasmussen, Justin Lee. "Investigations of evolutionary arms races and host diversity in avian brood parasite systems". Thesis, University of Canterbury. Biological Sciences, 2013. http://hdl.handle.net/10092/8959.

Testo completo

Abstract (sommario):

Obligate brood parasites rely solely on other species, the hosts, to incubate their eggs and raise their offspring, which often reduces the host’s reproductive output. This reproductive cost has led to the evolution of anti-parasite adaptations among hosts, which in turn, has led to better trickery by parasites, a process termed an evolutionary arms race. The objective of this thesis was to investigate host-parasite coevolutionary arms races to address questions of host-use diversity. Host diversity varies dramatically among brood-parasitic species, but reasons for variations in host-use among brood parasites are not well understood. In Chapter 2, I address questions on host diversity specifically, whereas I address questions about coevolutionary interaction between hosts and parasites in Chapters 3, 4 and 5 using two host-parasite systems, one in New Zealand and one in North America. Chapter 2 investigates if host diversity is constrained by aggressive nest defence behaviour. I compared the nest defence behaviour of the exclusive host of the shining cuckoo Chrysococcyx lucidus lucidus on the main islands of New Zealand, the grey warbler Gerygone igata, to two other potentially suitable hosts that are not currently parasitised, the fantail Rhipidura fuliginosa and the silvereye Zosterops lateralis. The results suggest that grey warblers are as aggressive as fantails and silvereyes towards shining cuckoos at the nest and thus, host specialisation in shining cuckoos in New Zealand, at least, does not appear to be the result of nest-defence constraints imposed by potential but unused host species. Chapter 3 investigates if red-winged blackbirds Agelaius phoeniceus, a species that typically accepts the eggs of parasites, recognises, as indicated by changes in incubation behaviour, when they have been parasitised by brown-headed cowbirds Molothrus ater. Recognition without rejection suggests that rejection may be context-dependent but the results suggest that red-winged blackbirds do not recognise when their nests have been parasitised by brown-headed cowbirds, at least at the egg stage. This study was the first to investigate if hosts that almost invariably accept the eggs of parasites recognise when they have been parasitised. Chapter 4 investigated the possibility of coevolutionary arms races occurring through olfactory channels in contrast to earlier work that focussed only on visual and auditory cues. Recent research has revealed that olfactory abilities in birds are more common than previously thought. Uropygial gland secretions are posited to be a key source of avian body odour and its composition has been found to vary among species and individuals as well as between the sexes. I compared gas-chromatography (GC-FID) traces of shining cuckoo preen wax to the GC-FID traces of the grey warbler, the only host of the shining cuckoo in mainland New Zealand, as well as the preen wax of seven other species for evidence of mimicry. Preliminary results suggest there is evidence for mimicry and the potential for odour-based nestling discrimination in grey warblers. Further tests recording the response of grey warblers to odour-manipulated nestlings are necessary. Finally, in Chapter 5, I investigated the response of the song thrush Turdus philomelos, a species that rejects the eggs of the common cuckoo Cuculus canorus and conspecifics at intermediate and low frequencies, respectively, to nest-odour manipulations using the preen wax of conspecifics and heterospecifics. The results suggest song thrush do not use odour to assess the risk of parasitism at least as indicated in terms of changes in incubation behaviour. Investigations of the role of olfaction in avian brood parasite systems can provide a better understanding of brood-parasite coevolution. Only by considering all channels of communication can we be sure to completely understand the coevolutionary dynamics between brood parasites and their hosts.

Gli stili APA, Harvard, Vancouver, ISO e altri

Bradley, Aoibhinn Maire. "Analysis of nonlinear spatio-temporal partial differential equations : applications to host-parasite systems and bubble growth". Thesis, University of Strathclyde, 2014. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24405.

Testo completo

Abstract (sommario):

The mountain hare population currently appears to be under threat in Scotland. The natural population cycles exhibited by this species are thought to be, at least in part, due to its infestation by a parasitic worm. We seek to gain an understanding of these population dynamics through a mathematical model of this system and so determine whether low population levels observed in the field are a natural trough associated with this cycling, or whether they point to a more serious decline in overall population densities. A generic result, that can be used to predict the presence of periodic travelling waves (PTWs) in a spatially heterogeneous system, is reported. This result is applicable to any two population host-parasite system with a supercritical Hopf bifurcation in the reaction kinetics. Application of this result to two examples of well studied host-parasite systems, namely the mountain hare and the red grouse systems, predicts and illustrates, for the first time, the existence of PTWs as solutions for these reaction advection diffusion schemes. One method for designing bone scaffolds involves the acoustic irradiation of a reacting polymer foam resulting in a final sample with graded porosity. The work in this thesis represents the first attempt to derive a mathematical model, for this empirical method, in order to inform the experimental design and tailor the porosity profile of samples. We isolate and study the direct effect of the acoustic pressure amplitude as well as its indirect effect on the reaction rate. We demonstrate that the direct effect of the acoustic pressure amplitude is negligible due to a high degree of attenuation by the sample. The indirect effect, on reaction rate, is significant and the standing wave is shown to produce a heterogeneous bubble size distribution. Several suggestions for further work are made.

Gli stili APA, Harvard, Vancouver, ISO e altri

Wezena, Cletus Adiyaga [Verfasser], e Marcel [Akademischer Betreuer] Deponte. "The cytosolic glyoxalase systems of the host-parasite unit are dispensable during asexual blood-stage development of the malaria parasite Plasmodium falciparum / Cletus Adiyaga Wezena ; Betreuer: Marcel Deponte". Heidelberg : Universitätsbibliothek Heidelberg, 2018. http://d-nb.info/1177252058/34.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Okolo, C. J. "Studies on lectin binding sites of Glossina in relation to host parasite interactions with particular reference to Glossina trypanosome systems". Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293804.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Meizis, Roland [Verfasser], e Anita [Akademischer Betreuer] Winter. "Metric two-level measure spaces : a state space for modeling evolving genealogies in host-parasite systems / Roland Meizis ; Betreuer: Anita Winter". Duisburg, 2019. http://d-nb.info/1191693414/34.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Più fonti

Libri sul tema "Host-Parasite systems"

Keeling, Matthew James. The ecology and evolution of spatial host-parasite systems. [s.l.]: typescript, 1995.

Cerca il testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Okolo, C. J. Studies on lectin binding sites of Glossina in relation to host parasite interactions with particular reference to Glossina trypanosome systems. Salford: University of Salford, 1991.

Cerca il testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

1942-, Cabello Felipe C., Pruzzo Carla e North Atlantic Treaty Organization. Scientific Affairs Division., a cura di. Bacteria, complement, and the phagocytic cell. Berlin: Springer-Verlag, 1988.

Cerca il testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Schmid-Hempel, Paul. Evolutionary Parasitology. 2^a ed. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198832140.001.0001.

Testo completo

Abstract (sommario):

Parasites are ubiquitous and shape almost every aspect of their hosts, including physiology, behaviour, life histories, the structure of the microbiota, and entire communities. Hence, parasitism is one of the most potent forces in nature and, without parasites, the world would look very different. The book gives an overview over the parasite groups and the diversity of defences that hosts have evolved, such as immune systems. Principles of evolutionary biology and ecology analyse major elements of host–parasite interactions, including virulence, infection processes, tolerance, resistance, specificity, memory, polymorphisms, within-host dynamics, diseases spaces, and many other aspects. Genetics is always one of the key elements in these topics. Modelling, furthermore, can predict best strategies for host and parasites. Similarly, the spread of an infectious disease in epidemiology combines with molecular data and genomics. Furthermore, parasites have evolved ways to overcome defences and to manipulate their hosts. Hosts and parasites, therefore, continuously co-evolve, with changes sometimes occurring very rapidly, and sometimes requiring geological times. Many infectious diseases of humans have emerged from a zoonotic origin, in processes governed by the basic principles discussed in the different sections. Hence, this book integrates different fields to study the diversity of host–parasite processes and phenomena. It summarizes the essential topics for the study of evolutionary parasitology and will be useful for a broad audience.

Gli stili APA, Harvard, Vancouver, ISO e altri

Pasquier, Louis Du, e Ellen Hsu. Pathogen-Host Interactions: Antigenic Variation v. Somatic Adaptations. Springer, 2015.

Cerca il testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Pasquier, Louis Du, e Ellen Hsu. Pathogen-Host Interactions: Antigenic Variation v. Somatic Adaptations. Springer, 2016.

Cerca il testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Pasquier, Louis Du, e Ellen Hsu. Pathogen-Host Interactions: Antigenic Variation V. Somatic Adaptations. Springer London, Limited, 2015.

Cerca il testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Jones, Isabel, Andrea Lund, Gilles Riveau, Nicolas Jouanard, Raphael A. Ndione, Susanne H. Sokolow e Giulio A. De Leo. Ecological control of schistosomiasis in Sub-Saharan Africa: restoration of predator-prey dynamics to reduce transmission. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198789833.003.0015.

Testo completo

Abstract (sommario):

Human modification of the landscape can increase the transmission of schistosomiasis, a snail-borne parasitic infection prevalent in Sub-Saharan Africa. The construction of dams and irrigation schemes increases the habitat available for the freshwater snails that serve as the parasite’s intermediate host. Schistosomiasis is considered both a cause and consequence of poverty. The disease is treatable, but its persistence in the environment makes it difficult to prevent reinfection after treatment. Interventions that address the environmental source of infection are a necessary complement to mass treatment campaigns. We present a promising ecological solution for schistosomiasis control that harnesses predator-prey dynamics to suppress snail populations and parasite transmission. We present data on the ecological and epidemiological impacts of restoring Macrobrachium vollenhovenii, a freshwater prawn native to the Senegal River. Harnessing ecology to control disease transmission may be a viable strategy in other geographic regions and other disease systems.

Gli stili APA, Harvard, Vancouver, ISO e altri

Heyns, Chris. Tuberculosis and parasitic infestations involving the urogenital system. A cura di Rob Pickard. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199659579.003.0006.

Testo completo

Abstract (sommario):

Urogenital tuberculosis is caused by Mycobacterium tuberculosis, which evokes a granulomatous tissue reaction leading to caseous necrosis, fibrosis, and eventual calcification. It most commonly presents as cystitis with sterile pyuria but can show many other symptoms and signs requiring a high index of suspicion to make the diagnosis. Schistosomiasis (Bilharzia) affecting the urinary tract is caused by the flatworm Schistosoma haematobium. Humans are infested by contact with fresh water harbouring the intermediate snail host. Echinococcosis (hydatid disease), is caused by the tapeworm Echinococcus granulosis or multilocularis. Human infection results from close contact with the parasite host (usually dogs and sheep). Filariasis, caused by the roundworm Wuchereria bancrofti, is transmitted by mosquito bite

Gli stili APA, Harvard, Vancouver, ISO e altri

Boswell, Carl A. Immunological perspectives of a host-parasite system: Studies on the humoral and cellular components of Biomphalaria glabrata, New World host for Schistosoma mansoni. 1985.

Cerca il testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Capitoli di libri sul tema "Host-Parasite systems"

Hannon, Bruce, e Matthias Ruth. "Nicholson–Bailey Host–Parasite Interaction". In Modeling Dynamic Biological Systems, 267–72. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-05615-9_32.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Keeling, M. J., e D. A. Rand. "Spatial Correlations and Local Fluctuations in Host-Parasite Models". In From Finite to Infinite Dimensional Dynamical Systems, 5–57. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0732-0_2.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Antonelli, P. L., e T. J. Zastawniak. "Density Dependent Host/Parasite Systems of Rothschild Type and Finslerian Diffusion". In The Theory of Finslerian Laplacians and Applications, 13–31. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5282-2_2.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Hart, David T. "Leishmania Host-Parasite Interactions : The Development of Chemotherapeutic Targets and Specific Drug Delivery Systems I. Lipoprotein Mediated Antileishmanial Chemotherapy". In Host-Parasite Cellular and Molecular Interactions in Protozoal Infections, 203–11. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-72840-2_24.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Shutko, Anna P., Elena G. Shek, Lyudmila V. Tuturzhans, Lyudmila A. Mikhno e Elena V. Pashkova. "Sustainable Phytosanitary Development of the Host-Parasite System on the Example of Head Blight of Winter Wheat". In The Challenge of Sustainability in Agricultural Systems, 1037–44. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-72110-7_114.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Wake, Akira, e Herbert R. Morgan. "Recognition by the Immune System". In Host-Parasite Relationships and the Yersinia Model, 82–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-71344-6_8.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Olsnes, Sjur. "Protein Translocation from the Exterior to the Cytosol: Diphtheria Toxin as a Model System". In Molecular Recognition in Host-Parasite Interactions, 221–25. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3038-1_25.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Langlais, Michel, Guillaume Latu, Jean Roman e Patrick Silan. "Parallel Numerical Simulation of a Marine Host-Parasite System". In Euro-Par’99 Parallel Processing, 677–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/3-540-48311-x_95.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

McLean, Katherine D., e Meghan A. Duffy. "Ecological Context Influences Evolution in Host-Parasite Interactions: Insights from the Daphnia-Parasite Model System*". In Evolution in Action: Past, Present and Future, 289–307. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-39831-6_21.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Roszkowski, W., B. Wesokowska, H. L. Ko, K. Roszkowski, P. Ciborowski, J. Jeljaszewicz e G. Pulverer. "Influence of Mezlocillin Administration to Pregnant Mice on the Immune System of Their Offspring". In The Influence of Antibiotics on the Host-Parasite Relationship III, 231–36. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-73653-7_32.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Atti di convegni sul tema "Host-Parasite systems"

Sullivan, Adam, Xiaopeng Zhao e Chunlei Su. "Mathematical Modeling of Within-Host Dynamics of Toxoplasma Gondii". In ASME 2011 Dynamic Systems and Control Conference and Bath/ASME Symposium on Fluid Power and Motion Control. ASMEDC, 2011. http://dx.doi.org/10.1115/dscc2011-6133.

Testo completo

Abstract (sommario):

Toxoplasma gondii is a protozoan capable of replicating sexually in cats and asexually in other warm-blooded animals. By using a three dimensional mesh of both the brain and spleen, it is possible to simulate using a computational model to demonstrate the entire life-cycle within an intermediate host of the parasite as it completes the life-cycle using host cells of these organs. A cellular automata model is developed to demonstrate the dynamics of the parasite, where each cell follows the same set of rules for each discrete time-step. This cellular automata model allows for data simulations to be run of the parasite within a mouse and display graphical images and animations.

Gli stili APA, Harvard, Vancouver, ISO e altri

Kreshchenko, N. D., e N. B. Terenina. "IDENTIFICATION OF FMRFamide-LIKE NEUROPEPTIDES IN TREMATODES ACROLICHANUS AURICULATUS". In THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL. VNIIP – FSC VIEV, 2024. http://dx.doi.org/10.31016/978-5-6050437-8-2.2024.25.226-230.

Testo completo

Abstract (sommario):

For the first time, using the immunocytochemical analysis and confocal laser scanning microscopy, we studied the nervous system structure including FMRFamideimmunopositive (FMRFa-ip) nerve elements in trematode Acrolichanus auriculatus (Digenea, Allocreadiidae), an intestinal parasite of sturgeons. The study results revealed FMRFamide staining in the central parts of the nervous system of worms: in neurons and neurites of the cephalic ganglia, cerebral commissure, and three pairs of longitudinal nerve cords. The staining intensity was higher in nerve fibers as compared to the bodies of FMRFa-ip neurons. At the periphery of FMRFaip, neural elements were found in neurons and fibers that innervated the oral and ventral suckers, pharynx and esophagus. In the area where the distal parts of the reproductive system were located, near the gonopore, three FMRFa-ip neurons and a network of nerve fibers were visible. FMRFa-ip structures were identified around the excretory pore. The localization of FMRFa-ip nerve elements innervating the attachment organs and parts of the digestive, reproductive and excretory systems in A. auriculatus suggests their role in attachment to the host, and functioning of such organs and systems in trematodes, probably through the regulation of their musculature.

Gli stili APA, Harvard, Vancouver, ISO e altri

BRITTON, N. F. "EVOLUTION IN A HOST-PARASITE SYSTEM". In International Symposium on Mathematical and Computational Biology. WORLD SCIENTIFIC, 2009. http://dx.doi.org/10.1142/9789814271820_0009.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Shevchuk, T. I., S. S. Khliestova e T. B. Vasenko. "Evolution of the parasite-host system". In THE GREATEST HUMANKIND ACHIEVEMENTS IN HEALTHCARE AND VETERINARY MEDICINE. Baltija Publishing, 2024. http://dx.doi.org/10.30525/978-9934-26-401-6-21.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Gorshkov, V. Yu, O. E. Petrova, O. I. Parfirova, B. R. Islamov, N. E. Gogolev, R. F. Gubaev, A. G. Daminova et al. ""Equilibrium" in the parasite-host system: physiological foundations, molecular players". In IX Congress of society physiologists of plants of Russia "Plant physiology is the basis for creating plants of the future". Kazan University Press, 2019. http://dx.doi.org/10.26907/978-5-00130-204-9-2019-13.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Sodnomov, T. C., e I. A. Kutyrev. "STUDY ON POTENTIAL IMMUNOREGULATORY PROTEINS IN THE EXCRETORY-SECRETORY PRODUCTS OF CESTODES". In THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL. VNIIP – FSC VIEV, 2024. http://dx.doi.org/10.31016/978-5-6050437-8-2.2024.25.388-393.

Testo completo

Abstract (sommario):

This article studied excretory-secretory products of parasitic flatworms aimed at searching for potential immunoregulatory proteins. Immunoregulatory proteins are poorly studied at the moment. Recent years have showed increased interest in identifying immunoregulatory molecules produced by parasitic worms. Potential immunoregulatory proteins will make a significant contribution to the development of medicine and biotechnology and will make it possible to effectively treat allergic and other autoimmune diseases. The study used methods of bioinformatics, proteomics, and transcriptomics. Potential immunoregulatory proteins were identified in the Ligula interrupta secretome proteins and listed. Each protein was analyzed for possible immunoregulatory functions in the parasite-host system. Based on identification data of SEP proteins using parasite transcriptomes, annotation of secretome proteins (SEP) was made in the NCBI and Swissprot international databases. A table was compiled with identified potential immunoregulatory proteins. A functional analysis of each protein was performed. Protein functions were determined based on analysis of scientific articles, patents and publications. By comparing different proteins, it is possible to identify those that are similar in domain structure, phylogeny, and description. The discovered potential immunoregulatory proteins will make a significant contribution to the development of medicine and biotechnology and will make it possible to effectively treat allergic and other autoimmune diseases.

Gli stili APA, Harvard, Vancouver, ISO e altri

Bibik, O. I. "HISTOCHEMICAL REACTIVITY ASSESSMENT OF THE GLYCOCALYX IN TREMATODES BEFORE AND AFTER ANTHELMINTIC". In THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL. VNIIP – FSC VIEV, 2024. http://dx.doi.org/10.31016/978-5-6050437-8-2.2024.25.52-56.

Testo completo

Abstract (sommario):

The structural organization of the glycocalyx layer in contact with the plasma membrane of the trematode tegument is a mechanism that ensures parasite’s body homeostasis and homeorhesis, and therefore its shape and morphological structure preservation. The analysis by a common method of histological preparations made from trematodes before and after anthelmintics and histochemically stained for mucopolysaccharides in the tegument using light microscopy showed that the anthelmintic effect caused changes in the staining of structural components of the organ. After anthelmintics, histochemical reactivity and tinctorial properties of the glycocalyx located on the trematode tegument membrane surface changed. The color grade change in stained glycocalyx and tegument in trematodes after the drugs indicates quantity and quality redistribution of glycosaminoglycans that ensure vital physiological processes of helminths. Any damage to the glycocalyx structure and metabolic processes in its layer by an anthelmintic informs about changes in chemical nature of biocomponents of the surface part of the parasite's body. Severe swelling of the tegument and basal membrane due to increased permeability of boundary structures and interaction of water molecules with biopolymers causes their swelling with changing the conformational structure. Protective glycocalyx properties are disrupted, which means a reduction in absorption, adhesiveness and barrier functions of trematodes in the host-parasite system.

Gli stili APA, Harvard, Vancouver, ISO e altri

Rapporti di organizzazioni sul tema "Host-Parasite systems"

Aly, Radi, e John I. Yoder. Development of resistant crop plants to parasitic weeds based on trans-specific gene silencing. United States Department of Agriculture, gennaio 2013. http://dx.doi.org/10.32747/2013.7598146.bard.

Testo completo

Abstract (sommario):

Broomrapes (Orobanche/Phelipanchespp.) are holo parasitic plants that subsist on the roots of a variety of agricultural crops and cause severe losses to the yield quality and quantity. Effective methods for controlling parasitic weeds are scarce, with only a few known cases of genetic resistance. In the current study, we proposed an improved strategy for the control of parasitic weeds based on trans-specific gene-silencing of three parasite genes at once. We used two strategies to express dsRNA containing selected sequences of three Phelipancheaegyptiacagenes PaACS, PaM6PR and PaPrx1 (pma): transient expression using Tobacco rattle virus (TRV:pma) as a virus-induced gene-silencing (VIGS) vector and stable expression in transgenic tomato Solanumlycopersicum(Mill.) plants harboring a hairpin construct (pBINPLUS35:pma). siRNA-mediated transgene-silencing (20–24 nt) was detected in the host plants. Our results demonstrate that the quantities of PaACSand PaM6PR transcripts from P. aegyptiacatubercles grown on transgenic tomato or on Tobacco rattle virus-infected Nicotianabenthamianaplants were significantly reduced. However, only partial reductions in the quantity of PaPrx1 transcripts were observed in the parasite tubercles grown on tomato and on N. benthamianaplants. Concomitant with the suppression of the target genes, there were significant decreases in the number and weight of the parasite tubercles that grew on the host plants, in both the transient and the stable experimental systems. The results of the work carried out using both strategies point to the movement of mobile exogenous siRNA from the host to the parasite, leading to the impaired expression of essential parasite target genes. In light of the importance of parasitic weeds to world agriculture and the difficulty of obtaining resistance by conventional methods, we assume that genetic resistance based on the silencing of key metabolic genes in the parasite is now feasible. BARD Report - Project4622 Page 2 of 60

Gli stili APA, Harvard, Vancouver, ISO e altri

Houck, Marilyn, Uri Gerson e Robert Luck. Two Predator Model Systems for the Biological Control of Diaspidid Scale Insects. United States Department of Agriculture, giugno 1994. http://dx.doi.org/10.32747/1994.7570554.bard.

Testo completo

Abstract (sommario):

Hemisarcoptes (Acari: Hamisarcoptidae) is a parasite of scale insects (Diaspididae), tenacious pests of vascular plants. Hemisarcoptes also has a stenoxenic phoretic (dispersal) relationship with Chilocorus (Coleoptera: Coccinellidae). Chilocorus feeds on diaspidids, transports mites as they feed, and has been applied to the control of scales, with limited success. U.S.-Israeli cooperation focused on this mite-beetle interaction so that a two-component system could be applied to the control of scale insects effectively. Life history patterns of Hemisarcoptes were investigated in response to host plant type and physical parameters. Field and lab data indicated that mites attack all host stages of scales tested, but preferred adult females. Scale species and host plant species influenced the bionomics of Hemisarcoptes. Beetle diet also influenced survival of phoretic mites. Mites use a ventral sucker plate to extract material from Chilocorus, that is essential for development. Seven alkaloids were found in the hemolymph of Chilocorus and three were characterized. Examination of the subelytral surface of Chilocorus indicated that microsetae play a role in the number and distribution of mites a beetle transports. While Hemisarcoptes can be innoculatd into agroecosystems using various indigenous or imported Chilocorus species, the following are preferred: C. bipustulatus, C. cacti, C. distigma, C. fraternus, C. orbus, and C. tristis.

Gli stili APA, Harvard, Vancouver, ISO e altri

Freeman, Stanley, e Russell J. Rodriguez. The Interaction Between Nonpathogenic Mutants of Colletotrichum and Fusarium, and the Plant Host Defense System. United States Department of Agriculture, settembre 2000. http://dx.doi.org/10.32747/2000.7573069.bard.

Testo completo

Abstract (sommario):

The intent of this proposal was to study the interaction between nonpathogenic mutants of Colletotrichum magna and Fusarium oxysporum, and the cucurbit host defense system. We had shown previously that a nonpathogenic endophytic mutant path- 1 of C. magna, caused no visible disease symptoms but protected watermelon seedlings from disease caused by the wildtype isolate and F. o. niveum. Objectives were: 1) Determine the microscopic, biochemical and molecular genetic interaction between "protected" (path- 1 colonized) cucurbit hosts and wildtype isolates of C. magna; 2) Isolate non-pathogenic mutants of F.o. melonis and test feasibility for protecting plants against fungal diseases. We found that path-1 caused no visible disease symptoms in cucurbit seedlings but conferred disease resistance against pathogenic isolates of C. magna, C. orbiculare, and F. oxysporum. Disease resistance conferred by path-1 correlated to a decrease in the time of activation of host defense systems after exposure of path-1 colonized plants to virulent pathogens. This was determined by monitoring the biochemical activity of PAL and peroxidase, and the deposition of lignin. It appears that path-1-conferred disease resistance is a multigenic phenomenon which should be more difficult for pathogen to overcome than single gene conferred resistance. Based on the benefits conferred by path-1, we have defined this mutant as expressing a mutualistic lifestyle. REMI (restriction enzyme-mediated integration) nonpathogenic mutants were also isolated using pHA1.3 plasmid linearized with Hind III and transformed into wildtype C. magna. The integrated vector and flanking genomic DNA sequences in REMI mutant R1 was re-isolated and cloned resulting in a product of approximately 11 kb designated pGMR1. Transformations of wildtype C. magna with pGMR1 resulted in the same non-pathogenic phenotype. A nonpathogenic mutant of F.o. melonis (pathogenic to melon) was isolated that colonized melon plants but elicited no disease symptoms in seedlings and conferred 25 - 50% disease protection against the virulent wildtype isolate. Subsequently, nonpathogenic mutant isolates of F.o. niveum (pathogenic to watermelon) were also isolated. Their protection capacity against the respective wildtype parent is currently under investigation. This research has provided information toward a better understanding of host-parasite interactions; specifically, endophytes, pathogens and their hosts. It will also allow us to assess the potential for utilizing nonpathogenic mutants as biological control agents against fungal pathogens and isolating molecular genetic factors of pathogenicity in Fusarium.

Gli stili APA, Harvard, Vancouver, ISO e altri

Westwood, James H., Yaakov Tadmor e Hanan Eizenberg. Identifying the genes involved in host root perception by root parasitic weeds: Genetic and transcriptomic analysis of Orobanche hybrids differing in signal response specificity. United States Department of Agriculture, gennaio 2013. http://dx.doi.org/10.32747/2013.7598145.bard.

Testo completo

Abstract (sommario):

Seeds of the root parasitic plants of the genus Orobanchegerminate specifically in response to host-derived germination signals, which enables parasites to detect and attack preferred hosts. The best characterized class of germination stimulants is the strigolactones (SL), although some species respond to sesquiterpene lactones such as dehydrocostuslactone (DCL). Despite great progress in characterizing the SL signaling system in plants, the mechanism(s) by which parasite species detect specific compounds remains poorly understood. The goal of our project was to identify and characterize the genes responsible for stimulant specificity in O. cernuaand O. cumana. These two species are closely related, but differ in host range, with O. cernuaparasitizingSolanaceous crops such as tomato (and responding to SLs), and O. cumanaspecifically parasitizing sunflower (and responding to DCL). We used a genetic approach based on O. cernuax O. cumanahybrids to associate germination response with genes. We found that these parasite species each have multiple copies of KAI2d genes, which function in SL perception. In O. cernua, the OrceKAI2d2 responds to SL stimulants and is most consistently associated with hybrid lines that respond to SLs. For O. cumana, an apparently linked block of KAI2d genes was associated with response to DCL in hybrid lines, but we found no strong evidence that any of the OrcuKAI2d genes specifically recognize the DCL stimulant. Remarkably, one O. cumanagene, OrcuKAI2d5, responds to certain SLs in a genetic complementation assay, even though hybrid lines containing this gene show fidelity to DCL. In summary, we have identified the SL receptor in O. cernua, but the DCL receptor in O. cumanaremains unknown. Our data point to involvement of additional genes and yet greater levels of complexity regulating germination specificity in Orobanche. BARD Report - Project 4616 Page 2 of 8

Gli stili APA, Harvard, Vancouver, ISO e altri

Phillips, Donald A., Yitzhak Spiegel e Howard Ferris. Optimizing nematode management by defining natural chemical bases of behavior. United States Department of Agriculture, novembre 2006. http://dx.doi.org/10.32747/2006.7587234.bard.

Testo completo

Abstract (sommario):

This project was based on the hypothesis that nematodes interacting with plants as either parasites or beneficial saprophytes are attracted to their host by natural products. This concept was supported by numerous observations that parasitic nematodes are attracted to root exudates. Our overall goal was to identify nematode sensory compounds from root exudates and to use that information for reducing nematicide applications. We applied skills of the investigators to achieve three specific objectives: 1) Identify nematode behavioral cues (e.g., attractants or repellents) in root exudates; 2) Identify new natural nematicidal compounds; and 3) Combine a natural attractant and a nematicide into a nematode trap. Because saprophytic nematodes benefit plants by mineralizing organic matter, we sought compounds attractive primarily to parasitic nematodes. The project was constructed on several complementary foundations. First, data from Dr. Spiegel’s lab showed that under aseptic conditions Ditylenchus dipsaci, a parasite on onion, is attracted to certain fractions of onion root exudates. Second, PI Phillips had a sizeable collection of natural plant products he had identified from previous work on Rhizobium-legume interactions, which could be tested “off the shelf”. Third, Dr. Ferris had access to aseptic and natural populations of various saprophytic and parasitic nematodes. The project focused on five nematode species: D.dipsaci, Heterodera avenae, and Tylenchulussemipenetransat ARO, and Meloidogyne javanicand Caenorhabditis elegans at UCD. Ten pure plant compounds, mostly flavonoids, were tested on the various nematode species using six different assay systems. Results obtained with assorted test systems and by various scientists in the same test systems were essentially irreproducible. Many convincing, Many convincing, i.e. statistically significant, results in one system or with one investigator could not be repeated with other assays or different people. A recent report from others found that these compounds, plus another 30, were inactive as attractants in three additional parasitic nematode species (Wuyts et al. Nematology 8:89- 101, 2006). Assays designed to test the hypothesis that several compounds together are required to attract nematodes have thus far failed to find a reproducibly active combination. In contrast to results using pure plant compounds, complex unfractionated exudates from aseptic onion root reproducibly attracted D. dipsaci in both the ARO and UCD labs. Onion root exudate collection, separation into HPLC fractions, assays using D. dipsaci and MS-MS experiments proceeded collaboratively between ARO and UCD without any definitive identification of an active compound. The final active fraction contained two major molecules and traces of several other compounds. In the end, analytical studies were limited by the amount of onion root exudate and the complexity of the purification process. These tests showed that aseptic plant roots release attractant molecules, but whether nematodes influence that release, as insects trigger release of attractants from plants, is unknown. Related experiments showed that the saprophyte C. elegans stimulates its prey, Pseudomonas bacteria, to increase production of 2, 4-diacetylphloroglucinol (DAPG) a compound that promotes amino acid exudation by plant roots. It is thus possible that saprophytic nematodes are attracted primarily to their bacterial or fungal prey and secondarily to effects of those microorganisms on root exudation. These observations offer promising avenues for understanding root-zone interactions, but no direct routes to controlling nematodes in agriculture were evident. Extracts from two plant sources, Chrysanthemum coronarium and Sequoia sempervirens, showed nematicidal activity at ARO and UCD, respectively. Attempts to purify an active compound from S. sempervirens failed, but preliminary results from C. coronarium are judged to form a potential basis for further work at ARO. These results highlight the problems of studying complex movement patterns in sentient organisms like nematodes and the issues associated with natural product isolation from complex mixtures. Those two difficulties combined with complications now associated with obtaining US visas, slowed and ultimately limited progress on this project. As a result, US investigators expended only 65% of the $207,400 originally planned for this project. The Israeli side of the project advanced more directly toward its scientific goals and lists its expenditures in the customary financial report.

Gli stili APA, Harvard, Vancouver, ISO e altri

Offriamo sconti su tutti i piani premium per gli autori le cui opere sono incluse in raccolte letterarie tematiche. Contattaci per ottenere un codice promozionale unico!