Search results for "host"

¿Qué hacer con el Mediterráneo?

2003

Asexual multiplication of larval parasitic worms: a predictor of adult life-history traits in Taeniidae?

2001

The hypothesis that asexual multiplication inside the intermediate host and adult life-history traits within the final host are independent is tested among Cestoda. Using phylogenetic relationships among the Cestoda species, we can show that asexual multiplication appears to have been lost and recovered several times throughout Taeniidae evolution; this allows a comparison of the adult life-history traits of species with and without asexual multiplication at the larval stage. The adult trait considered is the size of the parasite, since numerous life-history traits, such as fecundity and longevity, are correlated with size. If adult traits are independent of whether the larval stage reprodu…

Insight into the role of cetaceans in the life cycle of the tetraphyllideans (Platyhelminthes: Cestoda)

2007

Abstract Four types of tetraphyllidean larvae infect cetaceans worldwide: two plerocercoids differing in size, ‘small’ (SP) and ‘large’ (LP), and two merocercoids referred to as Phyllobothrium delphini and Monorygma grimaldii . The latter merocercoid larvae parasitize marine mammals exclusively and exhibit a specialised cystic structure. Adult stages are unknown for any of the larvae and thus the role of cetaceans in the life cycle of these species has been a long-standing problem. The SP and LP forms are thought to be earlier stages of P. delphini and M. grimaldii that are presumed to infect large pelagic sharks that feed on cetaceans. A molecular analysis of the D2 variable region of the …

Host-manipulation by parasites with complex life cycles: adaptive or not?

2010

7 pages; International audience; The effect of host manipulation by parasites on trophic transmission to final hosts remains unclear. The transmission benefits gained by manipulative parasites are difficult to assess, and evidence for a causal link between manipulation and trophic transmission is missing. In addition, infected intermediate hosts can also be more vulnerable to predation by nonhosts, whereas recent theoretical advances indicate that the evolution of host manipulation does not require increased specificity in trophic transmission. We propose that a deeper consideration of the evolution of complex life cycles in helminth parasites might provide a different perspective on the ev…

Mediterranean Diplodus annularis (Teleostei: Sparidae) and its brain parasite: Unforeseen outcome

2005

Patterns of parasite load and aggregation of the bird trematode Cardiocephaloides longicollis in its main intermediate host in the Mediterranean, the annular sea bream, Diplodus annularis, were studied in a large sample collected off Valencia (Spain) and are discussed within the context of the parasite induced host mortality hypothesis. The metacercariae were located within large composite cysts of host origin in the ventricles of the optic lobes of the cerebrum. A weak immunological response was detected in older fish, which was significantly associated with the total parasite load. Although the mean abundance of C. longicollis showed a tendency to increase with host size, the infection le…

Differential influence of Pomphorhynchus laevis (Acanthocephala) on brain serotonergic activity in two congeneric host species.

2007

The physiological mechanisms by which parasites with complex life cycles manipulate the behaviour of their intermediate hosts are still poorly understood. In Burgundy, eastern France, the acanthocephalan parasitePomphorhynchus laevisinverses reaction to light in its amphipod hostGammarus pulex, but not inGammarus roeseli, a recent invasive species. Here, we show that this difference in manipulation actually reflects a difference in the ability of the parasite to alter brain serotonergic (5-HT) activity of the two host species. Injection of 5-HT in uninfected individuals of both host species was sufficient to inverse reaction to light. However, a difference in brain 5-HT immunocytochemical s…

Light-mediated host searching strategies in a fish ectoparasite, Argulus foliaceus L. (crustacea: branchiura).

2000

Argulus foliaceus, an obligate fish ectoparasite, can search for its hosts in both light and dark conditions and uses vision in the light. We have examined what searching mode is used at night, when the infection rate was at its highest, and which stimuli produced by the fish are most important. A change of illumination produced a clear difference in the searching behaviour of adult Argulus females. The mean swimming speed and the area explored were 3-4 times higher in the dark, when the parasite employed a cruising search strategy. This changed to an ambush (hover-and-wait) strategy in the light. The swimming activity is accompanied by changes in metabolic costs; the activity of the electr…

Comparative analyses of co-evolving host-parasite associations reveal unique gene expression patterns underlying slavemaker raiding and host defensiv…

2017

Abstract The transition to parasitism is a drastic shift in lifestyle, involving rapid changes in gene structure, function, and expression. After the establishment of antagonistic relationships, parasites and hosts co-evolve through reciprocal adaptations, often resulting in evolutionary arms-races. Repeated evolution of social parasitism and slavery among Temnothorax ants allows us to examine those gene expression patterns that characterize slavemaker raiding and reciprocal host defensive phenotypes. Previous behavioural studies have established that raiding strategies between Temnothorax slavemakers diverge, while host defense portfolios shift similarly under parasite pressure. We are the…

Species-specific genes under selection characterize the co-evolution of slavemaker and host lifestyles.

2017

Background The transition to a parasitic lifestyle entails comprehensive changes to the selective regime. In parasites, genes encoding for traits that facilitate host detection, exploitation and transmission should be under selection. Slavemaking ants are social parasites that exploit the altruistic behaviour of their hosts by stealing heterospecific host brood during raids, which afterwards serve as slaves in slavemaker nests. Here we search for evidence of selection in the transcriptomes of three slavemaker species and three closely related hosts. We expected selection on genes underlying recognition and raiding or defense behaviour. Analyses of selective forces in species with a slavemak…

Alkaline Phosphatase: Keeping the Peace at the Gut Epithelial Surface

2007

Vertebrates harbor abundant lipopolysaccharide (LPS) or endotoxin in their gut microbiota. Here we demonstrate that the brush border enzyme intestinal alkaline phosphatase (Iap), which dephosphorylates LPS, is induced during establishment of the microbiota and plays a crucial role in promoting mucosal tolerance to gut bacteria in zebrafish. We demonstrate that Iap deficient animals are hypersensitive to LPS toxicity through a mechanism mediated by Myd88 and Tumor Necrosis Factor Receptor (Tnfr). We further show that the endogenous microbiota establish the normal homeostatic level of neutrophils in the intestine through a process involving Myd88 and Tnfr. Iap deficient animals exhibit excess…