muramidase and Ectoparasitic-Infestations

Lesions ranging from surface wounds to deep tissue wounds caused by cormorant predation were observed on several species of the farmed fish in Pohořelice, Czech Republic. Two-year-old stocked common carp Cyprinus carpio harvested in late March were examined for ectoparasites and endoparasites, injuries extent, and lysozyme concentration in skin mucus. Additionally, three body condition indices were measured. Endoparasite infection occurred only scarcely. Wounded fish were more susceptible to the ectoparasites Gyrodactylus spp. and Dactylogyrus spp. (Monogenea), and Ichthyophthirius multifiliis (Ciliophora). The intensity of infection of other ectoparasites Eudiplozoon nipponicum (Monogenea), Argulus spp. (Branchiura) and trichodinids (Ciliophora) did not significantly differ between wounded and control groups of fish. Lysozyme concentration in fish mucus was significantly higher in wounded fish and was positively associated with both the extent of damaged epithelium and Gyrodactylus spp. abundance. There were no differences in Fulton's condition factor and lipid content in muscle and liver tissues between wounded and non-wounded fish. Higher values of spleen-somatic index in wounded fish corresponded to increased intensity of parasite infection, most likely reflecting changes in immune system of infected fish. Although our results did not show any significant effect of cormorant attacks on fish condition, the wounded fish had significantly higher parasite numbers which could impact the growth or survival of the fish throughout the production season.

Topics: Animals; Aquaculture; Birds; Carps; Czech Republic; Disease Susceptibility; Ectoparasitic Infestations; Fish Diseases; Fresh Water; Linear Models; Muramidase; Predatory Behavior; Seasons; Wounds and Injuries

Physiological, immunological and biochemical parameters of blood and mucus, as well as skin histology, were compared in 3 salmonid species (rainbow trout Oncorhynchus mykiss, Atlantic salmon Salmo salar and coho salmon O. kisutch) following experimental infection with sea lice Lepeophtheirus salmonis. The 3 salmonid species were cohabited in order to standardize initial infection conditions. Lice density was significantly reduced on coho salmon within 7 to 14 d, while lice persisted in higher numbers on rainbow trout and Atlantic salmon. Lice matured more slowly on coho salmon than on the other 2 species, and maturation was slightly slower on rainbow trout than on Atlantic salmon. Head kidney macrophages from infected Atlantic salmon had diminished respiratory burst and phagocytic capacity at 14 and 21 d post-infection (dpi), while infected rainbow trout macrophages had reduced respiratory burst and phagocytic capacities at 21 dpi, compared to controls. The slower development of lice, coupled with delayed suppression of immune parameters, suggests that rainbow trout are slightly more resistant to lice than Atlantic salmon. Infected rainbow trout and Atlantic salmon showed increases in mucus lysozyme activities at 1 dpi, which decreased over the rest of the study. Mucus lysozyme activities of infected rainbow trout, however, remained higher than controls over the entire period. Coho salmon lysozyme activities did not increase in infected fish until 21 dpi. Mucus alkaline phosphatase levels were also higher in infected Atlantic salmon compared to controls at 3 and 21 dpi. Low molecular weight (LMW) proteases increased in infected rainbow trout and Atlantic salmon between 14 and 21 dpi. Histological analysis of the outer epithelium revealed mucus cell hypertrophy in rainbow trout and Atlantic salmon following infection. Plasma cortisol, glucose, electrolyte and protein concentrations and hematocrit all remained within physiological limits for each species, with no differences occurring between infected and control fish. Our results demonstrate that significant differences in mucus biochemistry and numbers of L. salmonis occur between these species.

Topics: Alkaline Phosphatase; Animals; Copepoda; Disease Susceptibility; Ectoparasitic Infestations; Fish Diseases; Host-Parasite Interactions; Mucus; Muramidase; Oncorhynchus kisutch; Oncorhynchus mykiss; Phagocytosis; Salmo salar; Skin; Species Specificity

The changes in the activities of mucus hydrolytic enzymes and plasma cortisol levels were examined following infection of Atlantic salmon Salmo salar with the salmon louse Lepeophtheirus salmonis and these changes were compared with those resulting from elevated plasma cortisol. Salmon were infected at high (Trial 1; 178 +/- 67) and low (Trial 2; 20 +/- 13) numbers of lice per fish and the activities of proteases, alkaline phosphatase, esterase and lysozyme in the mucus, as well as plasma cortisol levels were determined. At both levels of infection, there were significant increases of protease activity over time (1-way K-WANOVA; Trial 1, p = 0.004; Trial 2, p < 0.001). On several sampling days, generally on later days in the infections, the mucus protease activities of infected fish were significantly higher than control fish (Student's t-tests; p < 0.05). In addition, zymography experiments demonstrated bands of proteases at 17 to 22 kDa in the mucus of infected salmon that were absent in the mucus from non-infected fish and absent in the plasma of salmon. The intensity of these protease bands increased in the mucus over the course of both infections. However, plasma cortisol levels were elevated only in the heavily infected fish from the first trial. At high infection levels (Trial 1), alkaline phosphatase activity was higher in the mucus of infected fish at all days (t-test, p < 0.05). However, at the lower infection level (Trial 2), the mucus alkaline phosphatase activity did not differ significantly between infected and non-infected fish. Esterase and lysozyme activities were very low and did not change with time nor between non-infected and infected salmon in either challenge. Mucus enzyme activities of cortisol-implanted salmon did not change over time, nor were there any differences in activities between cortisol-implanted and control salmon. The present study demonstrates biochemical changes resulting from sea lice infection of Atlantic salmon occurring at the site of host-pathogen interaction, the mucus layer. However, the origin of these enzymes, whether host or pathogen, remains to be determined.

Topics: Alkaline Phosphatase; Analysis of Variance; Animals; Crustacea; Drug Implants; Ectoparasitic Infestations; Endopeptidases; Esterases; Fish Diseases; Hydrocortisone; Mucus; Muramidase; Salmo salar; Skin

The influence of infection with the juvenile stages of the sea louse, Lepeophtheirus salmonis (Krøyer) on the response of rainbow trout Oncorhynchus mykiss (Walbaum) to a net confinement protocol was investigated. The experiment consisted of two groups of seawater-adapted rainbow trout, one which was exposed to a total of 4000 nauplii/copepodid stages of L. salmonis 30, 25 and 14 days prior to confinement. Confinement elicited a greater stress response in the lice-exposed fish, than in the controls, as seen by higher plasma cortisol and glucose levels. A reduced spleen somatic index in exposed fish following 6 h confinement coincided with increased erythrocyte and lymphocyte numbers in the blood. Circulating lymphocyte numbers were significantly reduced in both groups 24 h post-confinement, when a lower alternative complement activity was recorded in control fish. Prior to confinement, lice-exposed fish had an elevated serum lysozyme activity and reduced oxygen radical production by blood leukocytes. Following confinement, lysozyme activity was gradually reduced in lice-exposed trout. During confinement, oxygen radical production decreased in control fish and increased in infested fish. Overall, transient exposure to juvenile lice altered the response to a second stressor, which has implications for management procedures of L. salmonis exposed fish.

Topics: Animals; Crustacea; Ectoparasitic Infestations; Female; Fish Diseases; Hematocrit; Leukocytes; Male; Muramidase; Oncorhynchus mykiss; Spleen; Stress, Physiological