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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However, seasonal variations in pituitary LH content observed in non-infected fish were absent intestinzlis infected roach. Plerocercoids were most prevalent 5. 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.
February leading up to spawning in springAugust post spawning and December mid cycle.
Data were analysed using the Abi Prism sequence detection system Applied Biosystems. This appears to be related to the greater metabolic stress on infected males. 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.
Reproduction6; Furthermore, in vertebrate hosts, Taenia taeniaeformis appears to directly affect the testis in the rat Lin et al. Transcript levels were normalised to those of 18S rRNA and data for infected fish presented as a fold change relative to the values obtained for non-infected fish.
Correlations between body parameters were subjected to regression analysis. Further quantification was performed in sections of the ovaries to determine the extent of oocyte development. 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 in an inability of the gonads to respond to hormonal signals.
Growth rate of females was unaffected by Ligula but somatic weight was slightly increased. This not only supports the intesginalis by Arme that reproductive inhibitory effects are specific to Ligulabut also suggests that effects of the parasite extend to non-host species e.
However, an apparently increased LH production in the eel suggested possible species differences in the action on gonadotroph activity. Indeed, sexual maturation will occur every year in non-infected fish but not in infected ones. Because of the lack of sequence data available for roach, fragments of LH and the control gene 18S ribosomal RNA were amplified and sequenced to identify specific primers for use in real-time PCR.
Ligula intestinalis (Cestoda: Pseudophyllidea): an ideal fish-metazoan parasite model?
In addition, GSI recorded in this infection suggested that non-infected host populations were undergoing normal reproductive cycles. Ligula infection could also affect LH production by acting directly on the gonadotrophs. However, because of the low sample size in certain age classes of infected fish, body lengths were considered according to age class, and differences were less apparent.
However, the relationship between Ligula and the induction of a possible stress effect on intestinslis fish host has been recently questioned by the work of Loot et al. As an internal control, 18S rRNA was amplified in an identical manner.
Ligula intestinalis – Wikipedia
The latter has liula demonstrated in other cyprinids where positive and negative responses have been noted for GnRH and dopamine respectively for review see Peter 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. While roach were caught up intestiinalis 54 g in weight, fish exceeding 20 g were not infected with Ligula Fig. Ligula intestinaliswhich is found in the body cavity of certain cyprinid fish, inhibits lgula in both male and female 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.
Natural variations were found within the sampled population, i.
Although the mode of action of the parasite remains elusive, it is clear that the pituitary gland morphology and gonadotrophic hormone itestinalis are affected by the parasite.
Ligulosed and non-ligulosed roach were collected from the Altami Angling Club, Chester, Cheshire, UK during — at three times during the reproductive year: Given that fish infected with Ligula intestinalis do not exhibit normal behaviour patterns in terms of shoaling e.
For example, the expression of gonadotrophin hormones and their receptors e. Figures given are means with range.
WoRMS – World Register of Marine Species – Ligula intestinalis (Linnaeus, ) Gmelin,
Ligula intestinalis could affect reproductive development of the fish at any level of the reproductive axis, from the first key hormones, gonadotrophin-releasing hormones GnRHto the gonads. Further analysis of the — cohort of fish also revealed a similar trend in the association with parasitisation and growth parameters.
The gonads, however, are present but remain ,igula an immature state, irrespective of fish age or season. Previous studies have indicated effects of infection at the pituitary gland level.
The condition factor assumes that heavier fish of a given length are in better condition and eliminates variation attributable to gonadal development over the reproductive season.
In non-infected females, the ovaries contained large, mature eggs and several smaller, primary oocytes with only immature stages of development occurring post spawning. In addition, analogous effects have been shown when L. In order to do this, fragments of the R. Whilst it is true that gonadotrophs are much reduced in number, the cells that are present do appear to be functional, indicating that Ligula lihula neither completely prevents gonadotroph differentiation nor basal activity.
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.
Whether this is mediated by direct effects of Ligula products or general endocrine disruption requires elucidation.