In the present study, the effect of polycyclic musk compound tonalide (AHTN) in two concentrations was studied in male rainbow trout (Oncorhynchus mykiss, Walbaum 1792). A feeding trial was conducted with AHTN incorporated into feed granules. One concentration was environmentally relevant (854 µg/kg); the second one was 10× higher (8699 µg/kg). The fish were fed twice a day with the amount of feed at 1 % of their body weight. After an acclimatization period, the experimental phase in duration of six weeks followed. At the end of the experiment, fish were sampled and the biometrical data were recorded. Subsequently, hematological and biochemical tests, histopathological examination, analysis of oxidative stress markers and evaluation of endocrine disruption using plasma vitellogenin were performed. In conclusion, an increase of hematocrit for both AHTN concentrations was found, but no significant changes were observed in biochemical profile. Moreover, AHTN caused lipid peroxidation in caudal kidney tissue, which was confirmed by histopathological images. The long-lasting AHTN exposure could thus be harmful for maintaining homeostasis in the rainbow trout organism. However, the vitellogenin concentration seemed not to be affected by AHTN.
Copepods of the genus Achtheinus Wilson, 1908 (Pandaridae) are parasites of elasmobranchs that attach to their fins, gill slits and around the nostrils. Specimens of Achtheinus pinguis Wilson, 1912 were collected and examined using histology and scanning electron microscopy to determine their way of attachment to the host and the possible effect on the host. They insert their antennae deep into the dermis of the shark's skin, which causes the most damage due to possible tissue compression and/or fibrosis as well as rupture of the connective tissue. Additionally, the presence of the copepod on the skin causes cell erosion of the epidermal cells and thus reduces the number of epidermal layers. The maxillipeds are used to attach to the placoid scales that cover the shark's skin and probably serve to keep the copepod and inserted antennae in position. This is accomplished by the insertion of the placoid scales into the flaccid corpus of the maxillipeds. Observed damage seems to be negligible to the shark apart from the possibility of secondary infection., Susan M. Dippenaar, Anine Jordaan., and Obsahuje bibliografii
Two species of Myxobolus Bütschli, 1882 were found in yellow catfish Tachysurus fulvidraco (Richardson). A species of Myxobolus infecting the gills was morphologically identified as Myxobolus voremkhai (Akhmerov, 1960) and it was characterised here with additional morphological and molecular data. The other species of Myxobolus infecting the host's skin did not conform to any known myxosporean species. It is characterised by the presence of round, black or milky white plasmodia with black spots. Myxospores are pyriform in frontal view and lemon-shaped in lateral view, measuring 12.9-16.2 μm (14.6 ± 0.7 μm) in length, 8.1-10.8 μm (9.4 ± 0.5 μm) in width, and 6.1-8.1 μm (7.0 ± 0.4 μm) in thickness. Two ampullaceous polar capsules are slightly unequal in size, larger polar capsule 7.2-9.5 μm (7.9 ± 0.4 μm) long by 3.0-3.9 μm (3.5 ± 0.2 μm) wide, smaller capsule 6.9-8.0 μm (7.4 ± 0.3 μm) long by 2.9-3.9 μm (3.4 ± 0.2 μm) wide. Polar filaments are coiled with seven to nine turns. Histologically, the plasmodia develop in the stratum spongiosum of skin dermis, resulting in epithelial cell shedding and immunological cell infiltration. Given the morphological and molecular differences between this species and other species of Myxobolus, we proposed the name of Myxobolus pseudowulii sp. n. for this parasite from the skin of yellow catfish. Interestingly, some spores of the new species possess Henneguya-like caudal appendages. Phylogenetically, M. pseudowulii sp. n. and M. voremkhai infecting yellow catfish group together in one clade with other parasites of Siluriformes, indicating that parasites clustering according to the fish host order may be an important factor affecting the evolution of species within the Myxobolus clade., Bo Zhang, Yanhua Zhai, Yang Liu, Zemao Gu., and Obsahuje bibliografii