The effects of starvation on some epidermal mucus immune parameters in rainbow trouts

The skin of a fish acts as the primary protective agent against biological, physical, and chemical stress. However, the effects of such stressors on fish mucosal immune responses have been hardly investigated. Fasting or feed deprivation commonly is occurred in aquaculture due to season, production policies, or disease. This research was aimed to investigate the impacts of 20-day starvation on skin mucosal immune responses of rainbow trout. The results revealed that the enzymatic activities of lysozyme (LZM) and alkaline phosphatase (ALP), as well as the total immunoglobulins (Ig) level and bactericidal activities were significantly reduced in the skin mucus of fasted fish. No significant changes were observed in the esterase and protease activities. Bactericidal activity in the mucus of starved fish was significantly lower than control group after 20 days. Therefore, it could be strongly suggested that this species should not remain under starvation stress as this kind of stress impairs mucosal immune barriers which, in turn, could make the fish more susceptible to infections or harmful agents

The effects of hand-stripping on some epidermal mucus immune parameters in rainbow trout, Oncorhynchus mykiss

Fish epidermis functions as the first defense barrier against physical, chemical, and biological stressors. However, the effects of hand-stripping on fish mucosal immune responses have been hardly investigated. The present study investigated the effects of stripping procedures on skin mucosal immune responses of rainbow trout (Oncorhynchus mykiss) breeders. The skin mucus was sampled from six male and six female trout before and one week after the stripping handling. The results showed that stripping had significant effect on all parameters except protease activity, but gender had a significant effect only on the mucosal protease and alkaline phosphatase activity. The results did not show any effect of the interaction between stripping and gender on mucosal lysozyme activity. The data revealed that enzymatic activities of alkaline phosphatase, lysozyme, esterase, as well as the total immunoglobulin level and bactericidal activity were significantly reduced in the skin mucus of fish one week after the stripping. The reduction of immune parameters in the skin mucus could be related to immunosuppression caused by stripping stress which, in turn, might have made the fish more susceptible to microbial infections and diseases. Therefore, care should be taken during stripping to minimize the manipulation stress.

An investigation on the helminth parasites of Caspian turtle (Mauremys caspica) with a taxonomic note on recovered Falcaustra Lane, 1915 (Nematoda: Kathlaniidae) and Spiroxys Schneider, 1866 species (Nematoda: Gnathostomatidae)

In this study, the digestive tracts of the Caspian turtles (Mauremys caspica) were investigated for the presence of helminth infections. Specimens of roundworms were recovered from the large intestine and stomach of the Caspian turtles. The morphologic measures revealed the infection with nematodes of the genus Falcaustra and Spiroxys. However, some differences were found in the collected Falcaustra specimens compared to the previous descriptions. In parallel, samples were analyzed by sequencing of the ribosomal gene targets. The phylogenetic analysis showed that the Falcaustra species as members of superfamily Cosmocercoidea were grouped with some members of Ascaridoidea and Spiruroidea. Despite the significant morphologic differences, Spiroxys species formed a sister group with ascaroid and cosmocercoid roundworms. Therefore, our molecular findings revealed that the taxonomic position of both nematodes need be revised

Evaluation of polyethylene microplastic bio-accumulation in hepatopancreas, intestine and hemolymph of freshwater crayfish, Astacus leptodactylus

Microplastics (MPs) are one of the biggest environmental problems threatening aquatic life. The accumulation of MPs in the body of aquatic animals can play a role in transferring these pollutants into the food chain. These pollutants can significantly affect the physiology of aquatic animals. In this study, the bioaccumulation capability of MPs in the body of freshwater crayfish, Astacus leptodactylus has been evaluated. For this purpose, crayfish were exposed to 0, 500, and 1000 µg L-1 of polyethylene MPs (PE-MPs) for 28 days. Then, the accumulation of MPs in hemolymph, hepatopancreas, and intestine of crabs was investigated by Fourier transform infrared spectroscopy (FTIR). Bioaccumulation of PE-MPs in the hemolymph, hepatopancreas, and intestines was observed in the crayfish exposed to PE-MPs. This study showed that FTIR is a suitable method for identifying and measuring MPs in aquatic organisms

Histopathological changes in the skin and gut mucus layers of rainbow trout (Oncorhynchus mykiss) challenged with Ichthyophthirius multifiliis inactivated by gamma rays and formalin

Ichthyophthirius multifiliis, a protozoan parasite, is a significant problem for fish farmers and Aquarium fish worldwide. This study aimed to evaluate the immunization of rainbow trout with gamma-irradiated, formalin inactive, and live theronts of I. multifiliis. In this study, fish were exposed to gamma-irradiated, formalin-inactivated, and live I. multifiliis theronts. Then, the histopathological changes in the mucous layers of the skin and intestines were studied after 7 and 14 days of exposure. Although no significant morphological changes were observed in the skin and intestines of the treated fish, the number of skin goblet cells increased significantly in fish treated with formalin-inactivated, gamma-inactivated, and live trophonts on 7 and 14 days. Compared to the negative control group, an increase in epidermal thickness on the skin was observed in fish challenged with formalin-inactivated, gamma-inactivated, and live trophonts. The numbers of mucous cells/total enterocytes in the intestinal epithelium of fish exposed to gamma-irradiated, formalin-inactivated, and trophonts live were higher than in non-infected fish. Moreover, a significant increase was found in the mucous cell numbers of the pyloric fold in treated fish with gamma-irradiated and formalin inactive trophonts at the first and second weeks. The results showed that the gamma-irradiated trophonts and formalin inactive trophonts could be safe for use in rainbow trout against I. multifiliis

Effects of gamma-irradiated ethanolic extract of Iranian propolis on growth performance, immunological and haematological parameters in juvenile common carp (Cyprinus carpio L.)

This study evaluated the oral administration of gamma-irradiated ethanolic extract of Iranian propolis on juvenile common carp. Fish were assigned into five groups and fed on the basal diet (control group) and an enriched diet containing 0.5 g kg-1 of GI-EEP supplements for 45 days. Growth performance, haematological indices, and immunological parameters were measured. The results showed that oral administration of GI-EEP (0, 10, and 30 kGy) significantly improved the growth performance. However, GI-EEP dietary supplements had no significant effects on the survival rate, haematological indices, catalase activity and total mucosal immunoglobulins of fish. A significant increase in lysozyme activities and total immunoglobulins was observed in fish fed on GI-EEP. The results suggested that feeding fish with 50 kGy of GI-EEP decreased certain growth performance indices and immunological parameters. The highest superoxide dismutase activity was observed in the fish fed on 30 kGy of GI-EEP, while the SOD activity significantly decreased in fish fed on 50 kGy of GI-EEP. The overall results of this study showed the use of GI-EEP at 10 and 30 kGy in the diet could improve growth indices and increase the efficiency of the innate immune and cellular antioxidant capacity. In contrast, the biological impact of EEP treated at 50 KGy gamma rays may be significantly reduced due to changes in its quality

Growth performance and lysozyme activity of rainbow trout fingerlings fed with vitamin E and selenium, marjoram (Origanum spp.), and ajwain (Trachyspermum ammi) extracts

The aim of this study was to investigate the effects of vitamin E and selenium, marjoram (Origanum spp.), and ajwain (Trachyspermum ammi) extracts on growth performance and lysozyme activity of rainbow trout fingerlings. The results of this study showed that adding ajwain (1%) and marjoram (2%) extracts and Vitamin E plus selenium (1%) significantly increased (P < .05) the growth factors compared to the control group in rainbow trout. In addition, the survival rate (SR) was 100% after applying the oxygen shock test on trout fed with 1% and 0.5% ajwain extract and 0.5% vitamin E plus Selenium supplement, which was significantly higher than other groups (P < .05). Another finding showed that 1% vitamin E plus selenium supplement and diets containing ajwain and marjoram at the level of 1% had significantly the highest value compared to other groups (P < .05). The measured total antibodies level showed that the groups 1% vitamin E plus Selenium supplement, 1% marjoram, and 1% and 2% ajwain, respectively, had the highest levels compared to the control group. It was shown in the present study that feeding rainbow trout fingerlings with 1% ajwain and marjoram extracts and vitamin E plus selenium as dietary supplements improved growth factor, lysozyme activity and SR