Ontogenetic changes in helminth membrane function

Arme, C.

doi:10.1017/s0031182000085991

Cited by 19 publications

(16 citation statements)

References 102 publications

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“…diminuta does not multiply in the intermediate host; thus, the initial period of infection will be the most demanding of host resources. During these 12^15 days the oncosphere grows rapidly and develops into a mature metacestode, while using metabolites circulating in the haemolymph (Arme 1988). At the same time, the host will need to repair damage done to the midgut epithelium by oncospheres burrowing through from the gut (Lethbridge 1971).…”

Section: Discussionmentioning

confidence: 99%

A parasite that increases host lifespan

Hurd

Warr

Polwart

2001

Proc. R. Soc. Lond. B

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Tenebrio molitor is an intermediate host for the rat tapeworm, Hymenolepis diminuta. Parasite oncospheres hatch in the beetle midgut and burrow through into the haemocoel, where they rapidly grow and mature into metacestodes. Repair of damage incurred during invasion and the nutritional demands of the parasites are likely to impose costs on the host. Despite these costs, there is an overall very highly significant difference in survival time (p < 0.001) between infected and control populations of beetles, with a hazard ratio of 2.35 (control versus infected). Infected females showed a 40% increase in survival time to 50% mortality and males showed a 25% increase in survival time to 50% mortality. This parasite-induced increase in host longevity is discussed in the light of changes in resource allocation that may occur in infected beetles. Previous findings have demonstrated that reproductive success is significantly reduced in infected females. The outcome of changes in the reproductive effort made by male beetles is less clear. We suggest that the optimum trade-off between reproduction and longevity may be altered to favour longer host survivorship, which is likely to enhance parasite transmission.

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Section: Discussionmentioning

confidence: 99%

A parasite that increases host lifespan

Hurd

Warr

Polwart

2001

Proc. R. Soc. Lond. B

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“…Metacestodes are known to possess uptake sites for several monosaccharides and amino acids (Arme 1988) but cannot use Vg itself (Webb & Hurd 1996). As they compete directly for amino acids circulating in the haemolymph, all host tissues could be depleted of nutrients.…”

Section: Discussionmentioning

confidence: 99%

Direct manipulation of insect reproduction by agents of parasite origin

Webb

Hurd

1999

Proc. R. Soc. Lond. B

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Reproductive output of female Tenebrio molitor beetles is reduced upon infection with metacestodes of the rat tapeworm, Hymenolepis diminuta. We are using this as a model to investigate the adaptive signi¢cance of parasite-induced curtailment of insect reproduction. Production of the yolk protein vitellogenin (Vg) in the insect fat body is signi¢cantly reduced both in vitro and in vivo by metacestodes. Synthesis can be measured by using [14 C]L-leucine incorporation, followed by immunoprecipitation. In this paper we demonstrate that a signi¢cant decrease in [14 C]Vg can be produced by an acetic acid extract of the parasite. Conclusive evidence is presented that the active component(s) originate from the metacestodes: an extract of parasites grown entirely axenically has similar deleterious e¡ects. The developmental stage of the metacestode is important: immature (stage I^II) parasites had greater capacity to suppress Vg synthesis than mature ones (stage V^VI). Examination of the chemical nature of the e¡ector molecule(s) revealed that acetic-acid-extractable, boiling-resistant, pronase-sensitive agents in the molecular mass range 10^50 kDa reduced Vg synthesis by 47.4%. These data suggest that metacestodes produce a modulator molecule that directly a¡ects insect vitellogenesis and, therefore, that reduction of host ¢tness may confer a selective advantage upon the parasite.

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“…As in most aquatic invertebrates, diffusion has been suggested as the route of uptake of metal ions (Cross et al 2001). Although this possibility cannot be entirely discounted, other studies suggest the uptake of ions occurs via active transport using specialised 'channels ' (Fusco et al 1991), with more complex molecules such as glucose taken up via facilitated diffusion (Arme, 1988). Indeed Morley and co-workers studied the toxicity of cadmium to the survival of E. recurvatum in a 1 % glucose solution and found clear differences occurred (Fig.…”

Section: Survivalmentioning

confidence: 99%

Pollution toxicity to the transmission of larval digeneans through their molluscan hosts

2003

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The increased occurrence of pollutants in ecosystems is a continuing area of concern. It is known that numerous diseases of wild aquatic animals can occur with decreased or increased prevalences in areas associated with high or chronic levels of pollution. This may have serious implications for environmental health. There has consequently been an increasing number of laboratory and field studies on disease transmission under polluted conditions, especially focusing on digeneans of medical or economic importance. The effect of pollutants to the transmission of larval digeneans (miracidia, cercariae, metacercariae) and snail-digenean interactions is therefore considered. An overview and interpretation of the published literature on laboratory and field studies is provided. It is apparent from these studies that the influence of pollutants on digenean transmission is highly complex with much of the observed effects in the laboratory often masked by a complexity of other factors in the field. Future studies would benefit from a standardisation of experimental procedures, increasing the number of combined laboratory and field studies, and increasing the complexity of the experiments undertaken.

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Ontogenetic changes in helminth membrane function

Cited by 19 publications

References 102 publications

A parasite that increases host lifespan

A parasite that increases host lifespan

Direct manipulation of insect reproduction by agents of parasite origin

Pollution toxicity to the transmission of larval digeneans through their molluscan hosts

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