We have evaluated the therapeutic effect of a compound mixture of caprylic acid (200 mg/kg fish), organic iron (0.2% of diet) and mannan oligosaccharide (0.4% of diet) in gilthead sea bream, Sparus aurata Linnaeus, infected with Sparicotyle chrysophrii Beneden et Hesse, 1863 in controlled conditions. One hundred and ten reared and S. chrysophrii-free fish (197 g) located in a cement tank were infected by the parasite two weeks following the addition of 150 S. chrysophrii-infected fish (70 g). Growth parameters and gill parasitic load were measured in treated against control fish after a ten-week-period. Differences in final weight, feed conversion ratio, specific growth rate and feed efficiency were not statistically significant between the experimental groups, suggesting no evident effect with respect to fish growth during the study period. Although the prevalence of S. chrysophrii was not affected by the mixture at the end of the experiment, the number of adults and larvae was significantly lower. The mean intensity encompassing the number of adults and larvae was 8.1 in treated vs 17.7 in control fish. Individual comparisons of gill arches showed that the preferred parasitism site for S. chrysophrii it the outermost or fourth gill arch, consistently apparent in fish fed the modified diet and in control fish. In conclusion, the combined application of caprylic acid, organic iron and mannan oligosaccharide can significantly affect the evolution of infection with S. chrysophrii in gilthead sea bream, being capable of reducing adult and larval stages of the monogenean. However, no difference in growth improvement was observed after the trial period, potentially leaving space for further optimisation of the added dietary compounds., George Rigos, Ivona Mladineo, Chrysa Nikoloudaki, Anamarija Vrbatovic, Dimitra Kogiannou., and Obsahuje bibliografii
A new species of Merizocotyle Cerfontaine, 1894 (Monogenea: Monocotylidae) is described from the nasal tissues of three deep sea rajid skates: the southern thorny skate, Amblyraja doellojuradoi (Pozzi), broadnose skate, Bathyraja brachyurops (Fowler), and yellownose skate, Zearaja chilensis (Guichenot), collected off Buenos Aires Province, Argentina, southwest Atlantic Ocean. Two additional species of sympatric rajid, the white-dotted skate, Bathyraja albomaculata (Norman), and the Patagonian skate, Bathyraja macloviana (Norman), were also examined but no merizocotylines were found. The taxonomy of the Merizocotylinae is not widely accepted and, as a result, the status of Thaumatocotyle and Mycteronastes, and their proposed synonymy with Merizocotyle are currently under discussion. The new species differs from its congeners by having a unique haptoral structure, 6 peripheral loculi that are asymmetrically arranged (one much smaller, indistinctly located in the left or right side of the haptor). The presence of the new species in three sympatric species of Rajidae belonging to distinct genera and subfamilies, as well as its absence in sympatric congenerics indicates the lack of phylogenetic host specificity. Host ecology and geographical distribution appear to be more important than host phylogeny in determining the distribution of this parasite across potential hosts in the region. This constitutes the first record of Merizocotyle in the southwestern Atlantic Ocean.
Scanning and transmission electron microscopy (TEM) were used to study the histopathological effects of the monogenean Macrogyrodactylus clarii Gussev, 1961 on the gills of the catfish Clarias gariepinus (Burchell). Suction generated during attachment created 'footprints' on host surfaces in which the host tissues were elevated above the general gill surface. 'Footprints' were bordered by four clefts caused by the muscular flaps on the anterior, lateral and posterior margins of the haptor. The hamuli points penetrate the gill tissue but no evidence was found for the insertion of the marginal hooklets. At the site of attachment, host cells adjacent to the lateral flaps often appeared compressed and widely spaced with large intercellular spaces. Desquamation of these surface epithelia was also apparent and some of the widely spaced epithelial cells had pseudopodium-like processes. Cells within the upper surface epithelial layer of the host were vacuolated and necrotic. Ruptured blood capillaries (blood spaces) in the secondary gill lamellae contained atypical compressed erythrocytes, agranular and granular leucocytes and evidence of haemorrhaging. Cells with fibrotic cytoplasm, putative phagocytes and host mucous cells were evidence of a host response at the site of parasite attachment. The possible role of these cells is discussed in relation to host resistance against infection., Mohammed Mohammed El-Naggar, Joanne Cable, Safaa Zaky Arafa, Samir Ahmed El-Abbassy, Graham C. Kearn., and Obsahuje bibliografii