The aim of this study was to investigate the dominant species of Aeromonas in naturally infected African Sharptooth catfish, Clarias gariepinus, in Qena, Egypt and the distribution of two virulence genes among the isolates to assess their pathogenicity. Twenty-five isolates of Aeromonas were recovered from infected fish showing signs of septicemia. Restriction-fragment-length-polymorphism (RFLP) analysis of the 16S-rDNA amplified products demonstrated that the specie isolated were Aeromonas hydrophila (56%) and Aeromonas veronii (44%). Isolates were screened for the cytotoxic enterotoxin, act, and aerolysin, aerA, genes. The act gene was detected only in A. hydrophila, while the aerA gene was more frequently found among all isolates. Catfish challenged with an A. hydrophila isolate that have both the act and aerA genes showed higher mortalities (80.9%) and more severe signs of septicemia than those challenged with an isolate that lacks both genes studied.
Lactoferrin is a multifunctional protein that has roles in iron metabolism, cell generation and differentiation, and antibacterial, antiviral, and antiparasitic activity. The study aim was to evaluate the effect of dietary lactoferrin powder on the innate immune response and disease resistance of silver carp (Hypophthalmichthys molitrix)infected with Vibrio vulnificus. The study also investigates immune cells in different organs including gills, intestine, spleen, liver, and pancreas using light, scan electron microcopy. Two diet regimes, a basic diet and a 600-mg/kg bovine lactoferrinsupplemented diet were used. The fish were fed for 30 successive days. We included 270 apparently healthy silver carp (H. Molitrix) with an average body weight of 10 ± 2 g/fish. Addition of lactoferrin to the diet led to an increase in the activity of non-specific immune parameters; lymphocytes, and in the monocytes percentage, and in total protein, serum globulin, and albumin, with a corresponding increase in phagocytic activities and indices. The histological analysis revealed increase immune cells such as lymphocytes in intestine, rodlet cells in liver, gills, and pancreas, and the macrophages in liver, pancreas as well as spleen. The lactoferrin-supplemented diet significantly increased survival and disease resistance following V. vulnificus challenge, which seemed to correspond to an enhancement of non-specific immune functions in H. molitrix. Research Highlights• The study evaluates the effect of dietary lactoferrin powder on the innate immune response and disease resistance of silver carp (Hypophthalmichthys molitrix) infected with Vibrio vulnificus.• The study also investigates immune cells in different organs including gills, intestine, spleen, liver, and pancreas using light, scan electron microcopy.• Lactoferrin increases the activity of nonspecific immune parameters; lymphocytes, and in the monocytes percentage, and in total protein, serum globulin, and albumin, with a corresponding increase in phagocytic activities and indices.• The histological analysis revealed increase immune cells such as lymphocytes in intestine, rodlet cells in liver, gills, and pancreas, and the macrophages in liver, pancreas as well as spleen.
The present study investigated the effects of dietary supplementation of nanocurcumin (NCur = 150 ppm) in African catfish feed for 15 days along with two doses of florfenicol—a therapeutic dose (FFC1 = 10 mg/kg.BW) and a high dose (FFC2 = 30 mg/kg.BW). Serum biochemical parameters and histopathological changes in liver and kidney tissues were determined post-feeding. Additionally, fish were experimentally challenged with a virulent strain of Aeromonas veronii to explore the fish’s capacity to resist infections. Results indicated that the serum level of total protein was significantly elevated in the FFC2 + Ncur group compared with control, Ncur, and FFC2 groups. Total protein level was also higher in FFC1 + Ncur compared with that of the FFC1 group. Moreover, feeding NCur, FFC1 + Ncur, and FFC2 + Ncur resulted in a significant increase in globulin levels compared to control, FFC1, and FFC2-Fed groups. However, the albumin level was unaffected. Serum levels of AST, ALT, ALP, and urea significantly increased in FFC2-fed fish compared to controls indicating liver damage. The higher dosage of FFC2 induced histological alterations in the liver and kidney architecture, represented by a rupture of the central vein, cytoplasmic vacuolation, hepatocytes necrosis, and severe inflammation. Surprisingly, NCur inclusion improved most of the altered biochemical parameters and mitigated FFC-induced histological damage in the hepatic and renal tissues. Similarly, fish that were fed a combination of both FFC and Ncur showed a higher resistance when exposed to A. veronii infection, as the mortality rates were significantly lower than those of the control group. Our findings indicated that incorporating NCur into the diet can have multiple benefits for the sustainable aquaculture of African catfish. These advantages encompass mitigating drug-induced damage to the liver and kidney tissues, augmenting the therapeutic efficacy of FFC in a synergistic manner and providing protection against A. veronii infections.
Ammonia is one of the most harmful water quality parameters restricting the growth and survival of aquatic living organisms. As a result, fish must adapt to this stressor by modifying physiological processes that are governed by gene expression regulation. The aim of the present study was to investigate the expression profiles of antioxidant related gene, catalase (CAT) in common carp (Cyprinus carpio) fingerlings after exposure to 0.7 mg/l of unionized ammonia (UIA) in water. The relative gene expression was measured in liver, gills, and brain tissues at four time points (12 h, 2 d, 4 d, and 7 d post exposure). The expression level of CAT gene in the liver and brain peaked after 7 d of ammonia exposure by 13.3 and 5.2-folds, respectively, but in gills it upregulated only after 2 d (2.7-folds) and downregulated at the other time points. This study proved that exposure to ammonia affects the antioxidant status of common carp as indicated by the altered levels of expression of CAT gene.
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