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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Data were analysed using the Abi Prism sequence detection system Applied Biosystems. Fish exceeding 20 g were not infected with Ligula. Introduction Previous studies have revealed that several parasitic infections can affect host reproduction.

In the roach, our data also showed that Ligula infection exerts some inhibitory effects on body growth and condition, but these effects are small and would, therefore, not account for the complete blockade of puberty noted in ligulosed fish. Further analysis of the — cohort of fish also revealed a similar trend in the association with parasitisation and growth parameters.

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. Because of the small amount of gonadal tissue in infected roach weighing less than 0. Indeed, sexual maturation will occur every year in non-infected fish but not in infected ones. Figures given are means with range. A subset of four non-infected female fish from each group was used for histological analysis of gonadal development and two categories of oocytes were observed, i.

As in other vertebrates, body growth and condition have been suggested to act as triggers for the initiation intestlnalis puberty in fish, although the mechanisms by which such a trigger is initiated is still largely unknown for reviews see Peter et al. Furthermore, in vertebrate hosts, Taenia taeniaeformis appears to directly affect the testis in the rat Lin et al.

In addition, we have for the first time revealed that the LH pituitary content and mRNA levels are also significantly decreased in infected individuals. Comparison of body mass to condition factor of ligulosed and non-ligulosed roach. The use of a heterologous assay for carp LH was fully justified in intestinails of the high level of sequence identity of the roach molecule see below. Effects of parasitism on host: As has been noted previously by Kennedy et al.


Transcript levels were normalised to those of 18S rRNA and data for infected fish presented as a fold change kigula to the values obtained for non-infected fish. However, an apparently increased LH production in the eel suggested possible species differences in the action on gonadotroph activity.

The fact that this inhibition was not observed when we compared older fish may inntestinalis from the negative effect of sexual maturation on growth and condition e. As an internal control, 18S rRNA was amplified in an identical manner. Gonadal development Because of the small amount of gonadal tissue in infected roach weighing less ibtestinalis 0.

In addition, analogous effects have been shown when L. The fragments and nucleotides respectively obtained were cloned and sequenced Genbank accession numbers: Although the mode of action of the parasite remains elusive, it is clear that the pituitary gland morphology and gonadotrophic hormone production are affected by the parasite.

However, seasonal variations in GnRH cell activity in non-infected fish were not investigated, and it cannot therefore be deduced that GnRH cells or GnRH release are not affected in infected fish.

Importantly, it also revealed that the roach—parasite interaction under investigation is typical of that found in other sampled populations. The effects noted in the wild are reproducible with a intesstinalis plerocercoid implanted into a large mature fish, which precludes pressure effects on fish organs or general debilitation from parasite metabolic demands Arme The sample size is shown above each bar. Natural variations were found within the sampled population, i.

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

Given that fish infected with Ligula intestinalis do not exhibit normal behaviour patterns in terms of shoaling e. The distribution, cell number and staining intensity of both these types of neurones, which are considered to be the first steps in BPG axis activation, were not affected by Ligula Penlington et al.


Although individual variation was high, LH content of non-infected individuals was at its peak post-spawning August and lowest intestinallis the winter ligulx December; Fig. Infected fish have lower K values, reflecting a lower body growth rate. Discussion Our results have confirmed previous observations made by Armeon the biometric effects of Ligula intestinalis on its roach intermediate host.

Ligula intestinalis – Wikipedia

Eighteen species of fishes were collected during the open water and winter seasons from Dauphin Lake, Manitoba, Canada 51 degrees 17’N, 99 degrees 48’W and examined for plerocercoids of Ligula intestinalis L.

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.

Correlations between body parameters were subjected to regression analysis.

This appears to be related to the greater metabolic stress on infected males. Plerocercoids were most prevalent 5. 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 intestinalix. Our results have confirmed previous observations made by Armeon the biometric effects of Ligula intestinalis on its roach intermediate host.

In order to do this, fragments of the R. This not only supports the hypothesis by Arme that reproductive inhibitory effects are specific to Infestinalisbut also suggests that effects of the parasite extend to non-host species e. Ligula intestinaliswhich is found in the body cavity of certain cyprinid fish, inhibits reproduction in both male and female fish. Results Parasite burden Details of lugula used and effects of parasitism are shown in Table 1.