Evaluation of Arginine and Glutamine as Dietary Supplements to Enhance Edwardsiella ictaluri Vaccine Effectivness in Channel Catfish

Rapid expansion of the aquaculture industry in recent decades has resulted in infectious diseases emerging as a major constraint to fish production, causing large economical losses worldwide. Therefore, prevention practices are indispensable for maintaining the industry's profitability and sustainability. Vaccination is a proven effective strategy for disease control in aquaculture; however, improvements in vaccine efficacy are still needed. Because amino acid supplementation not only enhances fish growth but also immune responses, a series of experiments were conducted to test the hypothesis that dietary supplementation of arginine and glutamine, two amino acids with immunomodulatory roles, may promote growth and increase the efficacy of vaccination against Edwardsiella ictaluri in channel catfish. An initial experiment demonstrated that dietary arginine supplementation at 2 and 4% of diet enhanced growth and feed efficiency of channel catfish. Dietary arginine deficiency diminished plasma levels of arginine, citrulline, ornithine, glutamine and glutamate, and impaired innate performance of macrophages and neutrophils. In a separate experiment, dietary glutamine supplementation failed to enhance growth responses; however, supplementation at 2% of diet had strong positive effects on intestinal histology and enterocyte migration rate. In addition, serine, asparagine, glycine and threonine were increased in plasma of fish fed the diet with glutamine at 2%. A third experiment revealed that activated macrophages utilized large quantities of glutamine in media and to a lesser extent arginine. These two amino acids also were the most utilized by proliferating lymphocytes. Supplementing media with these amino acids positively modulated phagocytosis and bactericidal capacity of macrophages, as well as increased the proliferation rate of lymphocytes. A final experiment indicated that dietary supplementation of arginine (4%) and glutamine (2%) optimized the nutritional and immunological status of channel catfish, and enhanced responses to E. ictaluri vaccination. At the same time, this supplementation ameliorated some short-term adverse effects of vaccination on growth. Higher specific antibody titers, better lymphocyte responsiveness and survival to the bacterium were seen in vaccinated fish fed arginine- and glutamine-supplemented diets. These results support an expanded role of dietary arginine and glutamine manipulation as a tool to improve growth and vaccine efficacy of channel catfish

Evaluation of Arginine and Glutamine as Dietary Supplements to Enhance Edwardsiella ictaluri Vaccine Effectivness in Channel Catfish

Rapid expansion of the aquaculture industry in recent decades has resulted in infectious diseases emerging as a major constraint to fish production, causing large economical losses worldwide. Therefore, prevention practices are indispensable for maintaining the industry's profitability and sustainability. Vaccination is a proven effective strategy for disease control in aquaculture; however, improvements in vaccine efficacy are still needed. Because amino acid supplementation not only enhances fish growth but also immune responses, a series of experiments were conducted to test the hypothesis that dietary supplementation of arginine and glutamine, two amino acids with immunomodulatory roles, may promote growth and increase the efficacy of vaccination against Edwardsiella ictaluri in channel catfish. An initial experiment demonstrated that dietary arginine supplementation at 2 and 4% of diet enhanced growth and feed efficiency of channel catfish. Dietary arginine deficiency diminished plasma levels of arginine, citrulline, ornithine, glutamine and glutamate, and impaired innate performance of macrophages and neutrophils. In a separate experiment, dietary glutamine supplementation failed to enhance growth responses; however, supplementation at 2% of diet had strong positive effects on intestinal histology and enterocyte migration rate. In addition, serine, asparagine, glycine and threonine were increased in plasma of fish fed the diet with glutamine at 2%. A third experiment revealed that activated macrophages utilized large quantities of glutamine in media and to a lesser extent arginine. These two amino acids also were the most utilized by proliferating lymphocytes. Supplementing media with these amino acids positively modulated phagocytosis and bactericidal capacity of macrophages, as well as increased the proliferation rate of lymphocytes. A final experiment indicated that dietary supplementation of arginine (4%) and glutamine (2%) optimized the nutritional and immunological status of channel catfish, and enhanced responses to E. ictaluri vaccination. At the same time, this supplementation ameliorated some short-term adverse effects of vaccination on growth. Higher specific antibody titers, better lymphocyte responsiveness and survival to the bacterium were seen in vaccinated fish fed arginine- and glutamine-supplemented diets. These results support an expanded role of dietary arginine and glutamine manipulation as a tool to improve growth and vaccine efficacy of channel catfish

Decrements of Muscle Protein Synthesis with Unloading are Not Due to Insufficient Concentrations of Intramuscular Leucine

Skeletal muscle mass and strength play critical roles in quality of life, and significant muscle atrophy contributes to reduced function and can exacerbate some disease states. It is well-known that persistent reductions of mechanical loading in skeletal muscle result in degeneration. Generally, reductions of muscle protein synthesis are, at least in part, a major culprit with muscle loss under these conditions, and numerous countermeasures such as exercise and nutritional supplements, known to stimulate protein synthesis have been designed to maintain muscle mass under those conditions. Amino acid supplementation, particularly with branched-chain amino acids (BCAAs), has been suggested as a countermeasure to deter muscle loss during spaceflight and bed rest, suggesting that these important protein precursors are not sufficiently available to support muscle protein synthesis during mechanical unloading. The purpose of this study was to examine the effect of muscle loading/unloading on the free amino acid pool of skeletal muscle in order to determine if concomitant alterations of the amino acid availability impact known changes in muscle protein synthesis under these conditions. We hypothesized reduced protein synthesis during periods of chronic unloading would be due to rate-limiting concentrations of one or more amino acids in the cytosolic free pool. Specific amino acid concentrations of 29 amino acids commonly found in the skeletal muscle cytosolic free-pool were assessed with high-performance liquid chromatography (HPLC) in gastrocnemius muscles taken from male Sprague Dawley rats that were assigned to various hindlimb unloading groups or ambulatory controls, with and without exercise countermeasures. Of the 29 amino acids tested, only one amino acid (nonessential aspartic acid) displayed an instance of concentrations significantly below control values (p ≤ 0.05). Surprisingly, each of the BCAAs, known agonists of muscle protein synthesis, displayed significant elevations in free-pool concentrations in unloaded muscle, even though muscle protein synthesis, and ultimately muscle mass were diminished. Leucine, a potent stimulant of muscle protein synthesis was over two times higher than the leucine concentrations of control muscles, suggesting that leucine was not sufficient to stimulate protein synthesis under conditions of microgravity. It also indicates that amino acid supplementation as a countermeasure may be ineffective, as circulating levels of available BCAAs are already elevated. These results suggest that additional efforts are required to find a suitable defense against muscle atrophy due to mechanical unloading

The Effect of Aflatoxin-B1 on Red Drum (Sciaenops ocellatus) and Assessment of Dietary Supplementation of NovaSil for the Prevention of Aflatoxicosis

Aflatoxin B1 (AFB1) is a potent carcinogen that causes growth stunting, immunosuppression and liver cancer in multiple species. The recent trend of replacing fishmeal with plant-based proteins in fish feed has amplified the AFB1 exposure risk in farm-raised fish. NovaSil (NS), a calcium montmorillonite clay, has previously been shown to reduce AFB1 bioavailability safely and efficaciously in several mammalian species. This study was designed to: (1) evaluate AFB1 impact on cultured red drum, Sciaenops ocellatus, over the course of seven weeks; and (2) assess NS supplementation as a strategy to prevent aflatoxicosis. Fish were fed diets containing 0, 0.1, 0.25, 0.5, 1, 2, 3, or 5 ppm AFB1. Two additional treatment groups were fed either 5 ppm AFB1 + 1% NS or 5 ppm AFB1 + 2% NS. Aflatoxin B1 negatively impacted red drum weight gain, survival, feed efficiency, serum lysozyme concentration, hepatosomatic index (HSI), whole-body lipid levels, liver histopathological scoring, as well as trypsin inhibition. NovaSil inclusion in AFB1-contaminated diets improved weight gain, feed efficiency, serum lysozyme concentration, muscle somatic index, and intraperitoneal fat ratios compared to AFB1-treated fish. Although not significant, NS reduced AFB1-induced histopathological changes in the liver and decreased Proliferating Cell Nuclear Antigen (PCNA) staining. Importantly, NS supplementation improved overall health of AFB1-exposed red drum

Caracterización parcial de proteasas digestivas del chucumite (Centropomus parallelus)

Diversos estudios han abordado la caracterización de las diversas enzimas digestivas, lo cual es esencial para entender los tipos, modos de acción y nivel de actividad de dichas enzimas. Objetivos. La caracterización parcial de las proteasas digestivas se estudió en juveniles del chucumite (Centropomus parallelus, Poey 1869). Métodos. Se utilizaron técnicas bioquímicas y electroforéticas para la caracterización de proteasas. Resultados. La actividad de proteasas ácidas (estomacales) fue mayor a las proteasas alcalinas (intestinales). Asimismo, la actividad de la quimotripsina fue superior a la actividad de la tripsina. El pH óptimo para las proteasas estomacales fue de 2 con una alta estabilidad en el rango de pH 2-8, mientras que las proteasas intestinales mostraron dos picos con actividad a pH 8 y 10, siendo altamente estables a los pH 8 y 12. Las temperaturas óptimas se obtuvieron a 45 y 55 °C para proteasa estomacales e intestinales, respectivamente. Mediante el uso de inhibidores de proteasas se comprobó la presencia de pepsina en los extractos estomacales y de diversas serina proteasas en los extractos intestinales. Los zimogramas mostraron cinco bandas con actividad proteolítica alcalina (79.5, 48.9, 37.0, 29.0 y 22.5 kDa), las cuales fueron fuertemente inhibidas con PMSF, SBT1 y ovoalbúmina. Conclusiones. Por lo anterior, se considera que C. parallelus tiene una alta capacidad digestiva similar a otros peces marinos carnívoros estrictos

Larval development of the Mexican Snook, Centropomus poeyi (Teleostei: Centropomidae)

ABSTRACT We document for the first time the early ontogeny of Centropomus poeyi based on captive raised material representing 0-19 days posthatch (dph). The achievement of early developmental landmarks (i.e., yolk-sac depletion, flexion, development of fins) and changes in pigmentation are described (1.4 mm NL-10.6 mm SL; 0-19 dph) and documented for a subset of individuals using high quality photographs. The ontogeny of the viscerocranium is also described (2.4 mm NL-10.6 mm SL; 6-19 dph). Development in C. poeyi occurs over a short period with attainment of the juvenile stage (i.e., full complement of fin rays present in each fin) occurring by 6.9 mm SL. The ontogeny of external pigmentation in C. poeyi is marked by two trends throughout growth: (1) a decrease in pigmentation dorsally; and (2) an increase in pigmentation ventrally along the midline. Development of the viscerocranium begins with the appearance of the maxilla and dentary in individuals of 2.4 mm NL, coinciding with the depletion of the yolk-sac. By 10.6 mm SL all bones of the viscerocranium are present and teeth are present on all teeth-bearing bones of the adult. Aspects of early development in C. poeyi are compared with the congeners C. undecimalis and C. parallelus

The Effect of Aflatoxin-B1 on Red Drum (Sciaenops ocellatus) and Assessment of Dietary Supplementation of NovaSil for the Prevention of Aflatoxicosis

Aflatoxin B(1) (AFB(1)) is a potent carcinogen that causes growth stunting, immunosuppression and liver cancer in multiple species. The recent trend of replacing fishmeal with plant-based proteins in fish feed has amplified the AFB(1) exposure risk in farm-raised fish. NovaSil (NS), a calcium montmorillonite clay, has previously been shown to reduce AFB(1) bioavailability safely and efficaciously in several mammalian species. This study was designed to: (1) evaluate AFB(1) impact on cultured red drum, Sciaenops ocellatus, over the course of seven weeks; and (2) assess NS supplementation as a strategy to prevent aflatoxicosis. Fish were fed diets containing 0, 0.1, 0.25, 0.5, 1, 2, 3, or 5 ppm AFB(1). Two additional treatment groups were fed either 5 ppm AFB(1) + 1% NS or 5 ppm AFB(1) + 2% NS. Aflatoxin B(1) negatively impacted red drum weight gain, survival, feed efficiency, serum lysozyme concentration, hepatosomatic index (HSI), whole-body lipid levels, liver histopathological scoring, as well as trypsin inhibition. NovaSil inclusion in AFB(1)-contaminated diets improved weight gain, feed efficiency, serum lysozyme concentration, muscle somatic index, and intraperitoneal fat ratios compared to AFB(1)-treated fish. Although not significant, NS reduced AFB(1)-induced histopathological changes in the liver and decreased Proliferating Cell Nuclear Antigen (PCNA) staining. Importantly, NS supplementation improved overall health of AFB(1)-exposed red drum