J Parasitol. Aug;75(4) Changes in numbers and growth of Ligula intestinalis in the spottail shiner (Notropis hudsonius), and their roles in. Abstract. The tapeworm Ligula intestinalis occurs in the body cavity of its cyprinid second intermediate host, in this study the roach Rutilus rutilus, and inhibits. Since its use as a model to study metazoan parasite culture and in vitro development, the plerocercoid of the tapeworm, Ligula intestinalis, has.

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Discussion Our results have confirmed previous observations made by Armeon the biometric effects of Ligula intestinalis on its roach intermediate host.

Orrpheromonal stimuli which would normally be received within the group-shoaling situation are absent from infected individuals, which may enhance the delay in puberty Francis et al. The fragments and nucleotides respectively obtained were cloned and sequenced Genbank accession numbers: This may explain why the growth curves of infected and non-infected fish become more similar in older fish. As with length, in 4 year-old fish there was no statistically significant difference between the body mass of infected and non-infected individuals infected 8.

Because of the very small amount of gonadal tissue present in infected fish, and thus the problem of finding and confirming the presence of gonads without histological examination, the condition factor was calculated including the gonadal tissue in parasitised individuals. Materials and methods Fish Ligulosed and non-ligulosed roach were collected from the Altami Angling Club, Chester, Cheshire, UK during — at three times during the reproductive year: In contrast, in infected fish, only these immature stages of oogenesis were present throughout and no cyclical variations were recorded see Arme GSI leading up to spawning February varied between 0.

Importantly, it also revealed that the roach—parasite interaction under investigation is typical of that found in other sampled populations. Effects of parasitism on host: As has been noted previously by Kennedy et al.

Ligula infection could also affect LH production by acting directly on the gonadotrophs. Furthermore, peripheral stimulators and inhibitors, active at all levels of the brain—pituitary—gonadal BPG axis, may be targets of the putative hormonal disruption by Ligulawhich results intrstinalis an inability of the gonads to respond to hormonal signals. Download Figure Figure 2 Comparison of body mass to condition factor of ligulosed and non-ligulosed roach.


Data intestinakis analysed using the Abi Prism sequence detection system Applied Biosystems. This appears to be related to the greater metabolic stress on infected males. Previous studies have indicated effects of infection at the pituitary gland level. In addition, GSI oigula in this infection suggested that non-infected host populations were undergoing normal reproductive cycles. Further studies are required to ascertain the mechanisms by which Ligula induces its inhibitory effect on roach LH production.

Ligula intestinalis

As an internal control, 18S rRNA was amplified in an identical manner. Indeed, sexual maturation will occur every year in non-infected fish but not in infected ones. Based on increased mean somatic weight and skewness of the weight distribution for infected fish, we propose that infected spottails are subjected to size-selective mortality.

The following degenerate primers were used: These studies have led to the belief that the effects of Ligula on intestinali development may be intestinaliss through the pituitary gland.

WoRMS – World Register of Marine Species – Ligula intestinalis (Linnaeus, ) Gmelin,

As in other vertebrates, body growth and condition have been suggested to act as intstinalis for the initiation of puberty in fish, although the mechanisms by which ligjla a trigger is initiated is still largely unknown for reviews see Peter et al.

Because of the small amount of gonadal tissue in infected roach weighing less than 0. Ligulosed and non-ligulosed roach were collected from the Altami Angling Club, Chester, Cheshire, UK during — at three times during the reproductive year: However, seasonal variations in pituitary LH content observed in non-infected fish were absent in infected roach. However, an apparently increased LH production in the eel suggested possible species differences in the intestinaljs on gonadotroph activity. Young infected roach, 2 and 3 years intestinails, rarely attained the same body weight as their non-infected counterparts mean body mass: Whether this is mediated by direct effects of Ligula products or general endocrine disruption requires elucidation.

Furthermore, in vertebrate hosts, Intesinalis taeniaeformis appears to directly affect the testis in the rat Lin et al. The effects noted in the wild are reproducible with a small plerocercoid implanted into a large mature fish, which precludes pressure effects on fish organs or general debilitation from parasite metabolic demands Arme The majority of non-infected fish achieved sexual maturation by 2 years of age as determined by the presence of yolky oocytes and all non-infected females were mature by 3 years of age.

Investigations of the effect of Ligula on the production of the other gonadotrophin follicle-stimulating hormone are also required, especially considering the potential effect of the parasites on the early stages of gametogenesis. Comparison of body mass to condition factor of ligulosed and non-ligulosed roach.


Ligula intestinalis (Cestoda: Pseudophyllidea): an ideal fish-metazoan parasite model?

In order to do this, fragments of the R. Correlations between body parameters were subjected to regression analysis.

Introduction Previous studies have revealed that several parasitic infections can affect host reproduction. In this study, our objective was to establish whether gonadal inhibition induced by Ligula in its primary fish host, Rutilus rutilusis mediated through effects on pituitary gland hormone levels, i.

This suggested that Ligula infection decreases LH synthesis by inhibiting its expression and indicates that the levels of gonadotrophin-producing cells being affected by parasitisation are critical to normal reproductive function. Results Parasite burden Details of fish used and effects of parasitism are shown in Table 1.

The latter has been demonstrated in other cyprinids where positive and negative responses have been noted for GnRH and dopamine respectively for review see Peter et al. However, the relationship between Ligula and the induction of a possible stress effect on its fish host has been recently questioned by the work of Loot et al. Although this effect was dose dependent, significant differences were found between Ligula and a related tapeworm species, Schistocephalus solidus.

Ligula intestinalis (Cestoda: Pseudophyllidea): an ideal fish-metazoan parasite model?

I, infected fish; NI, non-infected fish; Liguula, female; M, male. Some of the contradictions in the literature may be attributed to underestimated prevalence due to increased numbers of spawning fish in the spring, mixed age-classes of Ligula in separate age-classes of fish, and differential effects on growth due to infection in male versus female hosts. The reproductive system in fish is particularly susceptible to stress and immediate cessation of reproductive function is not uncommon when fish are brought into captivity Wendelaar Bonga The sample size is shown above each bar.

It may not be surprising, therefore, that the presence of a large parasite burden, which could be considered as a potent stressor, resulted in the observed dramatic effects on host reproduction.