Monogenean Parasites (monogenean + parasite)

Distribution by Scientific Domains

Selected Abstracts

Alternative parasite development in transmission strategies: how time flies!

Abstract Among parasitic platyhelminths with complex life cycles, it has been well documented that transmission opportunities are the main forces shaping the diversity of life-history traits and parasite developmental strategies. While deviations in the development pathway usually involve shortening of life cycles, their extension may also occur following perception of remaining time by parasites. Polystoma gallieni, the monogenean parasite of Hyla meridionalis, is able to trigger two alternative developmental strategies depending on the physiological stage of the tadpoles upon which larvae attach. The distribution and reproductive outputs of both resulting phenotypes were surveyed to address questions about the dynamics of transmission in natural environments. Because modifications in the completion of life cycles can have drawbacks which may perturb the dynamic equilibrium of the resulting host,parasite systems, experimental infestations were also performed to assess parasite,parasite interactions. Our results suggest that the bladder adult phenotype, which involves transmission between frogs and tadpoles, is supplied secondarily by the branchial phenotype which involves transmission between tadpoles and metamorphs. They also support the occurrence of finely tuned trade-offs between hosts and parasites and highlight positive trends behind the extension of direct life cycles, in which host-derived signals account for the remaining time to achieve parasitic transmission. [source]

Secretory products of the haptoral reservoirs and peduncular glands in two species of Bravohollisia (Monogenea: Ancyrocephalidae)

Wey-Lim Wong
Abstract. Light and electron microscopy were used to characterize the structure of secretory cells and their products involved in attachment of two monogenean parasites of fish, in order to understand their role in the attachment process. In Bravohollisia rosetta and Bravohollisia gussevi, peduncular gland cells with two nuclei, granular endoplasmic reticulum, and Golgi bodies produce dual electron-dense (DED) secretory bodies with a homogenous electron-dense rind and a less electron-dense fibrillar core (oval and concave in B. rosetta and oval in B. gussevi). The DED secretory bodies are altered as they migrate from the gland cell to the haptoral reservoir, the superficial anchor grooves, and into the gill tissues. The contents of the DED secretory bodies are exocytosed into the reservoirs, fibrillar cores persisting in the matrix, some of which condense, forming highly electron-dense spherical bodies. Small, oval, electron-dense bodies occur in the grooves, while no inclusions are visible in the homogenous exudate within the gill tissues. The single tubular extension of the reservoir enters a bifurcate channel within the anchor via a concealed, crevice-like opening on one side of the anchor. The channel directs secretions into the left and the right grooves via concealed apertures. The secretions, introduced into the tissues by the anchors, probably assist in attachment. The secretions are manifested externally as net-like structures and observed in some cases to be still attached to the point of exudation, on anchors detached from the gill tissues. This suggests that despite having the anchors detached, the worms can still remain anchored to the gill tissues via these net-like structures. Based on this, it is postulated that the net-like secretions probably function as a safety line to anchor the worm during the onset of locomotion and in doing so reduce the risk of tearing host tissues. [source]

In vivo and in vitro activities of the seed extract of Piper guineense Schum. and Thonn. against skin and gill monogenean parasites of gold,sh (Carassius auratus auratus)

A. P. Ekanem
Abstract Methanol extracts of the seeds of Piper guineense (Piperaceae) were active against gold,sh (Carassius auratus auratus L. Pisces Cyprinidae) monogenean parasites. The seed extract of P. guineense was administered at different concentrations (0.5,2.0 mg/L) under in vivo and in vitro conditions. There was a higher ef,cacy of the effects of the extracts against ,sh parasites under in vitro situations than under in vivo. Three major compounds (piperanine, N -isobutyl (E,E)-2,4 decadienamide and ,,,, -dihydrowasanine) were identi,ed from the seed extract of Piper guineense by LC-MS analysis. Copyright 2004 John Wiley & Sons, Ltd. [source]