Catfish Serum Research Articles

Fatty acid composition on diet and carcasses, growth, body indices and profile serum of Asian redtail catfish ( Hemibagrus nemurus) fed a diet containing different levels of EPA and DHA

Fatty acid composition on diet and carcasses, growth, body indices and profile serum of Asian redtail catfish ( Hemibagrus nemurus) fed a diet containing different levels of EPA and DHA

Fatty acid composition on diet and carcasses, growth, body indices and profile serum of Asian redtail catfish ( Hemibagrus nemurus) fed a diet containing different levels of EPA and DHA.

Background: The Asian redtail catfish Hemibagrus nemurus is a promising commercial aquaculture freshwater big-sized Bagridae catfish across Asian countries such as the Mekong, Malay Peninsula, and Indonesia. This study analysed the effect of eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) supplementation in diets on changes in fatty acid compositions in feed and fish meat, lipid quality (atherogenic index and thrombogenic index), growth rate, body indicators, and serum metabolites of Hemibagrus nemurus juveniles . Methods: A total of 180 Asian redtail catfish (initial weight 54.80 ± 2.72 g) were fed four levels (0, 3,150, 6,300, and 9,450 mg of EPA+DHA/kg feed) sourced from fish oil. Diets were fed in triplicate in freshwater tarpaulin ponds, with 15 fish per tarpaulin pond. During the experiment, fish were fed 3% per day of the biomass weight. Results: Categorically, there were significant differences in the composition of fatty acids in the feed and fish meat. The atherogenic index was between 1.76 and 1.84, and the thrombogenic index was between 0.81 and 0.89 in all fish meat. Growth performance was significantly different between diets, while body indices did not make a significant difference between diets. The fish meat EPA and DHA showed positive linear relationships with diet EPA (p <0.001, r 2 = 90%) and DHA diet (p<0.001, r 2= 85%). Serum metabolites among treatments D2 and D3 diet-fed feed for 60 days did not significantly differ. Glucose (GLU) levels had moderate relationships with triglycerides (TAG) ( r 2= 65%), and GLU levels strongly correlated with low-density lipoprotein cholesterol (LDL-C) ( r 2= 81%). Conclusions: Based on diets and whole-body carcass compositions, growth performance, and serum metabolites, Asian redtail catfish fed a diet containing 6,300 mg of EPA+DHA/kg feed are best for food safety.

Fatty acid composition on diet and carcasses, growth, body indices and profile serum of Asian redtail catfish (Hemibagrus nemurus) fed a diet containing different levels of EPA and DHA

Background: The Asian redtail catfish Hemibagrus nemurus is a promising commercial aquaculture freshwater big-sized Bagridae catfish across Asian countries such as the Mekong, Malay Peninsula, and Indonesia. This study analysed the effect of eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) supplementation in diets on changes in fatty acid compositions in feed and fish meat, lipid quality (atherogenic index and thrombogenic index), growth rate, body indicators, and serum metabolites of Hemibagrus nemurus juveniles. Methods: A total of 180 Asian redtail catfish (initial weight 54.80 ± 2.72 g) were fed four levels (0, 3,150, 6,300, and 9,450 mg of EPA+DHA/kg feed) sourced from fish oil. Diets were fed in triplicate in freshwater tarpaulin ponds, with 15 fish per tarpaulin pond. During the experiment, fish were fed 3% per day of the biomass weight. Results: Categorically, there were significant differences in the composition of fatty acids in the feed and fish meat. The atherogenic index was between 1.76 and 1.84, and the thrombogenic index was between 0.81 and 0.89 in all fish meat. Growth performance was significantly different between diets, while body indices did not make a significant difference between diets. The fish meat EPA and DHA showed positive linear relationships with diet EPA (p &lt;0.001, r2 = 90%) and DHA diet (p&lt;0.001, r2 = 85%). Serum metabolites among treatments D2 and D3 diet-fed feed for 60 days did not significantly differ. Glucose (GLU) levels had moderate relationships with triglycerides (TAG) (r2 = 65%), and GLU levels strongly correlated with low-density lipoprotein cholesterol (LDL-C) (r2 = 81%). Conclusions: Based on diets and whole-body carcass compositions, growth performance, and serum metabolites, Asian redtail catfish fed a diet containing 6,300 mg of EPA+DHA/kg feed are best for food safety.

Study of enzyme-hydrolyzed soybean replacing fish meal and/or chicken meal on the growth of channel catfish (Ictalurus punctatus)

This study aimed to evaluate the effect of enzyme-hydrolyzed soybean (EHSB) to replace fish meal and chicken meal in channel catfish (Ictalurus punctatus) on the growth performance, serum biochemical indices and gastrointestinal structure of channel catfish. The channel catfish (initial weight: 21.25 ± 0.25 g) was fed four isonitrogenous, isolipidic and isophosphorous diets for 60 days. The control diet (CON group) contained 8% fish meal and 5% chicken meal. EHSB was used to replace fish meal (100%, RF group), chicken meal (100%, RC group), and 100% of fish meal and chicken meal (RFC group), respectively. The specific growth rate (SGR) and protein deposition rate (PR) of channel catfish in RF, RC and RFC groups were significantly increased compared to the control group and reached their peaks in RFC group (SGR: 2.92%, PR: 45.64%) (P < 0.05). The feed coefficient of channel catfish in RFC group (0.94) was significantly decreased compared to the control group (P < 0.05). The survival rate was not affected by the replacement of fish meal and chicken meal by EHSB (P > 0.05). The catalase and alanine aminotransferase activities in serum were significantly decreased in replacement groups compared to the control group (P < 0.05). Besides, the activities of superoxide dismutase and aspartate aminotransferase in serum of channel catfish were remarkably increased in the RFC group (24.22 U/L and 193.00 U/L, respectively) (P < 0.05). The replacement of fish meal and chicken meal by EHSB, either alone or simultaneously, significantly increased the crude protein (51.68% in RC group) and crude lipid (31.27% in RFC group) in whole body of channel catfish (P < 0.05). The crude lipid in muscle of channel catfish was markedly increased in RF (16.31%, dry matter) and RFC groups (16.45%, dry matter) (P < 0.05). Replacement of fish meal and chicken meal by EHSB could significantly increase the intestinal villi length and intestinal wall thickness, thus improving the digestive capacity of channel catfish. The gastric epithelial cells in the RFC group were plumper and more structurally integrated than in the control group. In summary, replacing 100% of fish meal and 100% of chicken meal with EHSB could effectively improve the growth performance, antioxidation and digestive capacities of channel catfish.

Assessing the effect of cadmium and Hibiscus sabdariffa calyx extract on the organ gravimetry and lipid profile of the liver and serum of African catfish (Clarias gariepinus)

Toxicity of cadmium to all lives especially the aquatic life cannot be quantified due to their deleterious effect usually caused as a result of their incessant and uncontrollable discharged into the aquatic environment. The present study was undertaken to assess the effect of cadmium and Hibiscus Sabdariffa Calyx Extract on the Organ Gravimetry and Lipid Profile of the Liver and Serum of African Catfish (Clarias gariepinus). Forty juvenile catfish were divided into four groups containing ten fish with average weight 170 ± 2kg per group [Group A, Control (–HSCE – Cd), Group B (+HSCE), Group C (+Cd) and Group D (+HSCE + Cd)]. Group B and D were administered a daily dose of 40ml/kg body weight of Hibiscus sabdariffa calyx extracts (HSCE) (0.25%v/v) for 14 days while groups C and D were exposed to the same dose containing 0.3 mg of Cd/L daily for 14 days. The result shows that there was significant decrease (p&lt;0.05) in the liver total- and LDL- cholesterol of fish exposed to HSCE and HSCE + Cd treated groups when compared to control and cadmium treated group. The triglycerides concentration of liver and serum was significantly increased (p&lt;0.05) in fish exposed to cadmium when compared to the control and HSCE + Cd treated group respectively. SOD activity was significantly increase (p&lt;0.05) in the serum of catfish exposed to Cd when compared to control. However, the liver-body weight ratio was significantly decreased in Cd and Cd + HSCE treated groups relative to the control. It is evident from the result obtained in this study that HSCE has protective effect against cadmium intoxicated fish (Clarias gariepinus).

Hemolysin Co-regulated Family Proteins Hcp1 and Hcp2 Contribute to Edwardsiella ictaluri Pathogenesis.

Edwardsiella ictaluri is a Gram-negative facultative intracellular pathogen causing enteric septicemia of catfish (ESC), a devastating disease resulting in significant economic losses in the U.S. catfish industry. Bacterial secretion systems are involved in many bacteria's virulence, and Type VI Secretion System (T6SS) is a critical apparatus utilized by several pathogenic Gram-negative bacteria. E. ictaluri strain 93–146 genome has a complete T6SS operon with 16 genes, but the roles of these genes are still not explored. In this research, we aimed to understand the roles of two hemolysin co-regulated family proteins, Hcp1 (EvpC) and Hcp2. To achieve this goal, single and double E. ictaluri mutants (EiΔevpC, EiΔhcp2, and EiΔevpCΔhcp2) were generated and characterized. Catfish peritoneal macrophages were able to kill EiΔhcp2 better than EiΔevpC, EiΔevpCΔhcp2, and E. ictaluri wild-type (EiWT). The attachment of EiΔhcp2 and EiΔevpCΔhcp2 to ovary cells significantly decreased compared to EiWT whereas the cell invasion rates of these mutants were the same as that of EiWT. Mutants exposed to normal catfish serum in vitro showed serum resistance. The fish challenges demonstrated that EiΔevpC and EiΔevpCΔhcp2 were attenuated completely and provided excellent protection against EiWT infection in catfish fingerlings. Interestingly, EiΔhcp2 caused higher mortality than that of EiWT in catfish fingerlings, and severe clinical signs were observed. Although fry were more susceptible to vaccination with EiΔevpC and EiΔevpCΔhcp2, their attenuation and protection were significantly higher compared to EiWT and sham groups, respectively. Taken together, our data indicated that evpC (hcp1) is involved in E. ictaluri virulence in catfish while hcp2 is involved in adhesion to epithelial cells and survival inside catfish macrophages.

Influence of developments in the field of high-energy physics on the biochemical parameters of the blood serum of Clarius catfish grown in RAS

The data on the influence of innovative hydrological developments in the field of high energy physics on the biochemical parameters of blood serum of Clarius catfish grown in a closed water supply installation are presented. The essence of innovative developments in the field of high energy physics consists in the treatment of water in which fish and feed are grown with crystal structures created by a group of Russian scientists. The energy of these crystal structures has a beneficial effect on the biological activity of objects, improving their natural properties. During the experiment, the content of total bilirubin, enzymes aspartate aminotransferase (AsT) and alanine aminotransferase (AlT), total protein, creatinine, glucose, urea, alkaline phosphatase, macro elements (calcium and phosphorus) were determined. The biochemical blood parameters of the fish in the control and experimental groups had significant differences in some parameters, which may indicate a positive effect of feeds with a modified molecular structure and biologically active liquid (BAF) on the organism of Clarius catfish.

Haematology, plasma biochemistry and serum of table size African catfish, Clarias gariepinus, naturally infected with Listeria species in Oyo State

Fresh fish in Nigeria is gaining acceptance as a result of knowledge of its nutritive value; however, it is mostly assessed by the consumers by mere looking. Fish that looks apparently healthy may not be actually healthy. Haematology, plasma biochemistry and serum are some good parameters for the assessment of fish health. This study evaluated the haematology, plasma biochemistry and blood enzymes of farm-raised African catfish, Clarias gariepinus, naturally infected with listeriosis in Oyo State. Fish were collected from 36 farms using stratified method. A total of 108 fish were collected where 37 were positive for listeriosis. The blood of the affected fish was used for this study. Haematology, plasma biochemistry and blood enzyme analysis were determined. Fish from Oyo zone had the highest PCV, Hb, RBC and MCHC with 29.33 ± 2.96%, 10.04 ± 1.04 dL, 3.55 ± 0.09 × 106/μL and 34.24 ± 0.74%, respectively; the highest heterocytes (39.00 ± 5.33%), eosinophils (4.00 ± 1.10%), basophils (0.50 ± 0.55%) and hetero:lymphocyte ratio (0.71 ± 0.14) were recorded in fish from Ogbomosho zone; WBC, platelets, lymphocytes and monocytes were highest in fish from Saki zone with 18.72 ± 0.44 × 106/μL, 224.00 ± 3.61 × 103/μL, 71.33 ± 1.53% and 3.33 ± 0.58%, respectively, while fish from Ibadan/Ibarapa zone had the highest MCV (163.40 ± 44.23 fL) and MCH (52.77 ± 14.95 pg). Total protein and globulin were highest in fish from Oyo zone with 6.61 ± 0.37 and 1.70 ± 0.38 g/dL, respectively, while albumin and A:G ratio were highest in fish from Ogbomosho zone. Fish from Ogbomosho zone had the highest AST, ALP, creatinine and glucose with 194.17 ± 10.11 μL, 232.17 ± 63.64 μL, 0.72 ± 0.19 μL and 277.50 ± 90.36 mg/dL, respectively; urea and cholesterol were highest in fish from Saki zone (8.30 ± 0.46 μL and 263.67 ± 3.51 mg/dL) while Ibadan/Ibarapa zone had the highest ALT (37.11 ± 14.72 μL). The study concluded that fish that are physically healthy which is the common factor used to judge the health status of the fish by majority of consumers do not mean that the fish are healthy. Haematology, biochemistry and blood enzymes of the fish infected with listeriosis are lower than the recommended levels. Therefore, further research should be carried out to detect a quicker way of examining healthy fish.

Purinergic signalling as a potential pathway for trichlorfon induced-inflammation and impairment of the immune response using freshwater silver catfish

Adenosine triphosphate (ATP) and adenosine (Ado) are the main molecules of the purinergic signalling involved in toxicological mechanisms induced by pesticides. These molecules participate in the regulation of immune and inflammatory responses due to their interaction with purinereceptors in the extracellular medium. In the literature, the ATP and Ado are related with pro-inflammatory and immunomodulatory effects, respectively. Thus, the aim of this study was to evaluate whether the purinergic signalling can be considered a potential target for trichlorfon-induced inflammation and impairment of the immune response. Seric and splenic triphosphate diphosphohydrolase (NTPDase) activities using ATP as substrate were reduced at 22 mg/L after 48 h of exposure compared to the control group, while NTPDase activity using ADP as substrate was lower only in the serum of silver catfish at the same period. On the other hand, seric and splenic adenosine deaminase (ADA) activities and metabolites of nitric oxide (NOx) levels were increased at 22 mg/L after 48 h of exposure compared to the control group. The enzymatic activity of the purinergic signalling did not return to control levels after 48 h of recovery period in trichlorfon-free water. Based on these evidences, we concluded that trichlorfon interferes with the purinergic signalling, causing impairment of the immune and inflammatory responses by reducing ATP hydrolyses, possible leading to its accumulation in the extracellular environment. In addition, there is an increase in Ado desamination and possible reduction of it in the extracellular medium, leading to a self-sustained pro-inflammatory deleterious cycle. In summary, the purinergic signalling can be considered a potential target for trichlorfon-induced inflammation and impairment of the immune response in freshwater silver catfish at exposure to 22 mg/L.

Xanthine oxidase activity exerts pro-oxidative and pro-inflammatory effects in serum of silver catfish fed with a diet contaminated with aflatoxin B1.

Several studies have associated the involvement of xanthine oxidase (XO) activity, a source of uric acid and reactive oxygen species (ROS), to pro-oxidative and pro-inflammatory effects during pathological conditions. Considering this, the aim of this study was to evaluate whether upregulation on seric XO activity may be a pathway involved in the oxidative stress in fish exposed to a diet contaminated with aflatoxin B1 (AFB1 ), as well as whether it may be considered a pathway involved in ROS and NOx production. Xanthine oxidase activity, as well as the uric acid, ROS and NOx levels increased in serum of fish fed with a AFB1 -contaminated diet on days 14 and 21 post-feeding compared to fish fed with a basal diet. Based on these evidences, upregulation of seric XO activity induces pro-oxidant and pro-inflammatory profiles in serum of fish fed with a AFB1 -contaminated diet due to excessive formation on uric acid. Also, the excessive uric acid induces the release of pro-oxidant and pro-inflammatory mediators, as ROS and NOx, also contributing to oxidative and inflammatory profiles. In summary, the upregulation on seric XO activity may be considered a pathway involved in the oxidative stress of fish exposed to a diet contaminated with AFB1 .

Stress-related genes promote Edwardsiella ictaluri pathogenesis.

Edwardsiella ictaluri is a Gram-negative facultative anaerobic rod and the causative agent of enteric septicemia of channel catfish (ESC), which is one of the most prevalent diseases of catfish, causing significant economic losses in the catfish industry. E. ictaluri is resistant to complement system and macrophage killing, which results in rapid systemic septicemia. However, mechanisms of E. ictaluri stress responses under conditions of host environment are not studied well. Therefore, in this work, we report E. ictaluri stress responses during hydrogen peroxide, low pH, and catfish serum stresses as well as during catfish invasion. E. ictaluri stress responses were characterized by identifying expression of 13 universal stress protein (USP) genes (usp01-usp13) and seven USP-interacting protein genes (groEL, groES, dnaK, grpE, and clpB, grpE, relA). Data indicated that three usp genes (usp05, usp07, and usp13) were highly expressed in all stress conditions. Similarly, E. ictaluri heat shock proteins groEL, groES, dnaK, grpE, and clpB were highly expressed in oxidative stress. Also, E. ictaluri grpE and relA were highly expressed in catfish spleen and head kidney. These findings contribute to our understanding of stress response mechanisms in E. ictaluri stress response, and stress-related proteins that are essential for E. ictaluri could be potential targets for live attenuated vaccine development against ESC.

Identification of Differentially Regulated Edwardsiella ictaluri Proteins During Catfish Serum Treatment.

Edwardsiella ictaluri is a facultative, intracellular, gram-negative bacterium that causes enteric septicemia of catfish (ESC). Edwardsiella ictaluri is known to be resistant to defense mechanisms present in catfish serum, which might aid in its use of a host's bloodstream to become septicemic. However, the precise mechanisms of the survival of E. ictaluri in host serum are not known. Analysis of the response of E. ictaluri to the host serum treatment at a proteomic level might aid in the elucidation of its adaptation mechanisms against defense mechanisms present in catfish serum. Thus, the objective of this study was to identify differentially regulated proteins of E. ictaluri upon exposure to naïve catfish serum. Two-dimensional difference gel electrophoresis (2D-DIGE) followed by in-gel trypsin digestion and MALDI-TOF/TOF analysis were used for identification of differentially expressed E. ictaluri proteins. A total of 19 differentially regulated proteins (7 up- and 12 downregulated) were identified. Among those were four putative immunogenic proteins, two chaperones and eight proteins involved in the translational process, two nucleic acid degradation and integration proteins, two intermediary metabolism proteins, and one iron-ion-binding protein. Further research focusing on the functions of these differentially expressed proteins may reveal their roles in host adaptation by E. ictaluri.

Purinergic system displays an anti-inflammatory profile in serum of silver catfish experimentally infected with Streptococcus agalactiae: An attempt to ameliorate the inflammatory response

The purinergic system is recognized to modulate extracellular adenosine triphosphate (ATP) and related nucleotides through the activities of triphosphate diphosphohydrolase (NTPDase), 5′-nucleotidase, and adenosine deaminase (ADA), thereby playing an essential role in the immunoregulation of inflammatory and immune responses. Thus, the aim of this study was to evaluate whether the purinergic system can improve the inflammatory response in fish experimentally infected with Streptococcus agalactiae through the modulation of seric NTPDase, 5′-nucleotidase and ADA activities. Seric NTPDase (ATP as substrate) and 5′-nucleotidase activities increased in silver catfish experimentally infected with S. agalactiae compared with the uninfected control group, while seric ADA activity decreased. Based on this evidence, our findings suggest that regulation of adenine nucleotide hydrolysis occurs in an attempt to restrict the inflammatory process and improve the immune system by hydrolyzing excess extracellular ATP. On the other hand, downregulation of seric ADA activity may be an attempt to augment extracellular adenosine (a molecule with anti-inflammatory effects) levels. In summary, the purinergic system is capable of modulating the immune and inflammatory responses during fish streptococcosis.

Innate immune response of channel catfish Ictalurus punctatus mannose-binding lectin to channel catfish virus (CCV).

The channel catfish virus (CCV) is a pathogenic herpesvirus that infects channel catfish Ictalurus punctatus in pond aquaculture in the southeastern USA. Mannose-binding lectin (MBL), an innate immune protein, could play an important role in the innate response of channel catfish by binding to CCV. Cell cultures of CCV were grown in channel catfish ovary cells (CCOC). A dot-immunoblot enzyme-linked immunosorbent assay was done to determine the binding ability of 5 mo old channel catfish serum MBL (26.2 µg ml-1) to CCOC infected with CCV. Two separate nitrocellulose membrane blotting techniques were done using uninfected and infected CCOC. The uninfected CCOC decreased by 29.3 and 33.4% in their binding of channel catfish MBL when compared with infected CCOC using the 2 membrane procedures. The combined average binding ability of channel catfish MBL towards infected CCOC was therefore 31.4% greater when comparing the infected and uninfected CCOC. Normalization equation values of MBL for the 5 mo old catfish were compared for the 2 membrane binding procedures. The 2 normalization values were very close (142 and 150) in binding ability of MBL to the infected CCOC. The 5 mo catfish serum had twice the concentration of MBL (26.2 µg ml-1) compared to 7 mo catfish serum (13.2 µg ml-1), and the binding percentage of 5 mo serum was 2.4 times greater in infected than in uninfected cells. This demonstrates that the binding of channel catfish serum MBL to CCV is concentration dependent and is related to serum concentrations of MBL.

Purification and development of ELISAs for two forms of vitellogenin in Indian walking catfish, Clarias batrachus (L.).

Two forms of vitellogenin (Vg: Vg1 and Vg2) were purified from the plasma of estradiol-17β (E2)-treated Indian walking catfish, Clarias batrachus, by gel filtration and adsorption chromatography. Native Vg1 and Vg2 had apparent molecular masses of 375 and 450kDa, respectively, and both Vgs resolved into two similar major bands (95 and 67kDa) in SDS-PAGE under reducing condition. Polyclonal antisera raised against each form of Vg were absorbed with a combination of hypophysectomized male catfish serum proteins and alternate Vg to ensure specificity. Immunological analyses verified the presence of Vg1 and Vg2 in the plasma of female catfish. Homologous ELISAs were developed for Vg1 and Vg2 using their respective harvested antisera, which exhibited the detection limit of 100ngml-1 for Vg1 and 40ngml-1 for Vg2, and low level of cross-reactivity (not parallel to the standard) was found with alternate Vg in each assay. Treatment of male catfish with E2 induced both Vgs showing a proportionate ratio of Vg1 to Vg2 at 5.6:1. Plasma concentrations of both Vgs measured by ELISAs at different reproductive phases of field collected female catfish increased in accordance with the ovarian development, keeping the proportionate ratio of Vg1 to Vg2 at about 2:1 in fish undergoing vitellogenesis during prespawning period and 1:20 during spawning period, suggesting that Vg1 may be the major Vg to contribute in yolk formation, whereas Vg2, besides its role in yolk formation, may facilitate other physiological functions. The present study, thus, demonstrates the occurrence of two unequally synthesized Vgs in the catfish.

Characterization of an IgM-like immunoglobulin from silver catfish (Rhamdia quelen) serum and its use for the production of polyclonal antibodies and development of immunoassays

Abstract: Knowledge on fish immunoglobulin (Ig) characteristics and the availability of monoclonal or polyclonal antibodies to fish Igs are essential to evaluate the humoral immune response and the Ig distribution on leukocyte cells. We demonstrated that silver catfish serum Ig is composed of one immunodominant H chain with approximately 75k Da and one L chain with approximately 28 kDa, similar to human IgM. Rabbit polyclonal antibodies to the catfish IgM-like Ig recognized both the H and L chain and were useful in developing an indirect ELISA to measure the production of antibodies in fish immunized with bovine serum albumin. Dot blot and western blot cross-reactivity studies indicated a wide degree of epitope sharing amongst Ig from several Siluriformes and Characiformes fish indigenous to Brazilian rivers. In these fish species, polyclonal antibodies reacted mostly with the H chain. The results presented here are central to the development of tools and strategies to investigate the antibody production to inoculated antigens and tissue distribution of Ig molecules in native fish species. Furthermore, because of the wide range of cross-reactivity, polyclonal antibodies to silver catfish IgM-like Ig might be used to develop immunoassays to measure the humoral immune response in other fish species.

Zebrafish (Danio rerio) bioassay for visceral toxicosis of catfish and botulinum neurotoxin serotype E

Visceral toxicosis of catfish (VTC), a sporadic disease of cultured channel catfish (Ictalurus punctatus) often with high mortality, is caused by botulinum neurotoxin serotype E (BoNT/E). Presumptive diagnosis of VTC is based on characteristic clinical signs and lesions, and the production of these signs and mortality after sera from affected fish is administered to sentinel catfish. The diagnosis is confirmed if the toxicity is neutralized with BoNT/E antitoxin. Because small catfish are often unavailable, the utility of adult zebrafish (Danio rerio) was evaluated in BoNT/E and VTC bioassays. Channel catfish and zebrafish susceptibilities were compared using trypsin-activated BoNT/E in a 96-hr trial by intracoelomically administering 0, 1.87, 3.7, 7.5, 15, or 30 pg of toxin per gram of body weight (g-bw) of fish. All of the zebrafish died at the 7.5 pg/g-bw and higher, while the catfish died at the 15 pg/g-bw dose and higher. To test the bioassay, sera from VTC-affected fish or control sera were intracoelomically injected at a dose of 10 µl per zebrafish and 20 µl/g-bw for channel catfish. At 96 hr post-injection, 78% of the zebrafish and 50% of the catfish receiving VTC sera died, while no control fish died. When the VTC sera were preincubated with BoNT/E antitoxin, they became nontoxic to zebrafish. Histology of zebrafish injected with either VTC serum or BoNT/E demonstrated renal necrosis. Normal catfish serum was toxic to larval zebrafish in immersion exposures, abrogating their utility in VTC bioassays. The results demonstrate bioassays using adult zebrafish for detecting BoNT/E and VTC are sensitive and practical.

Depletion of melamine and cyanuric acid in kidney of catfish Ictalurus punctatus and trout Oncorhynchus mykiss.

A risk assessment conducted in 2007 identified significant knowledge gaps about tissue residues of melamine and related triazine analogs such as cyanuric acid in animals that had eaten contaminated food. The USFDA subsequently designed studies to determine residue levels in muscle, serum, and kidneys of catfish and trout given a single gavage dose of 20mg/kg body weight (BW) of melamine, cyanuric acid, or 20mg/kg BW of both compounds simultaneously. Renal triazines were determined by LC-MS/MS at postdose days 1, 3, 7, 14, 28 (and day 42 for trout). When dosed individually, melamine and cyanuric acid kidney residues depleted much faster than those in fish given both compounds together. Combined dose residue depletion was punctuated by extreme outliers due to the formation of persistent renal melamine cyanurate crystals.

Purification, characterization and seasonal variation of mannose-binding C-type lectin in Ictalurid catfish

Mannose-binding C-type lectin (MBL) was purified by mannan-agarose affinity chromatography from blue catfish D + B ( Ictalurus furcatus) and channel catfish NWAC 103 ( Ictalurus punctatus) sera. The MBLs of blue catfish D + B and channel catfish NWAC 103 strains have not been purified by affinity chromatography, characterized and quantified. The affinity-purified and 2-ME reduced catfish MBLs showed one band of 66 kDa for blue catfish D + B, and one band of 63 kDa for channel catfish NWAC 103 by SDS-PAGE and Western blotting. Amino acid composition analysis (mol%) of the isolated catfish MBLs was done. The amount of methionine-S present in blue catfish D + B (0.78 mol%) was 2.2-times greater when compared with channel catfish NWAC 103 (0.35 mol%). The amount of proline present was 1.9-times greater in channel catfish NWAC 103 (8.0 mol%) when compared with blue catfish D + B (4.3 mol%). Tyrosine (2.5 mol%) was present in blue catfish D + B but not detected in channel catfish NWAC 103. N-terminal amino acid sequencing by Edman degradation for the first 10 residues gave two amino acid sequences of XRQPESFRIV and XXEDGYGKMF that were identical for both blue catfish D + B and channel catfish NWAC 103. This could represent the presence of two different isoforms of catfish MBL. Blue catfish D + B had 21.3 μg of MBL/ml of serum. Channel catfish NWAC 103 (#1 serum pool) had 15.1 μg of MBL/ml of serum (obtained in late Fall season), and channel catfish NWAC 103 (#2 serum pool) had 10.2 μg of MBL/ml of serum (obtained in Spring season). A seasonal variation in the channel catfish serum MBL was therefore seen. A standard curve for μg/ml of MBL in catfish serum was constructed with these data. The presence of MBL in blue catfish D + B and channel catfish NWAC 103 sera should be important in their innate immunity and resistance to Edwardsiella ictaluri and other microbial infections. This study describes the presence of MBL in these two Ictalurus species and evidence for a C-type lectin complement pathway of innate immunity. The channel catfish is used in aquaculture in the Southeast USA and is susceptible to bacterial infections acquired from its pond environment.

Characterization of mannose-binding protein isolated from the African catfish ( Clarias gariepinus B.) serum

Lectins are carbohydrate-binding proteins which are involved in many biological functions including cell adhesion, phagocytosis, complement activation and innate immunity. This paper reports the first isolation of mannose-binding protein (MBP), designated as CgMBP or kumpolin1, from the serum of the African catfish, Clarias gariepinus (Burchell, 1822), a robust freshwater fish farmed extensively in Africa and South East Asia. Mannan-agarose affinity column was used to purify the mannose-binding protein from the serum. Molecular weight determination using reducing SDS-PAGE and non-reducing SDS-PAGE analyses revealed a single band close to 35 kDa and 28 kDa protein, respectively. Positive microbial cell agglutination activities of the African catfish mannose-binding protein were observed against Candida albicans, Saccharomyces cerevisiae, Aeromonas hydrophila, Bacillus subtilis, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa. The functional properties of the MBP were tested under various conditions by using S. cerevisiae as the test organism. Agglutination activity of MBP was found to occur at pH 3–7. It required 0.5 mM calcium and was inhibited by 1 mM EDTA.