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Aeromonas hydrophila induces apoptosis in pufferfish, Takifugu obscurus
Get PDFAeromonas hydrophila is a Gram-negative opportunistic pathogen causing motile aeromonad septicemia, which results in great economic losses in freshwater fish farming. In this study, we investigated the effect of A. hydrophila on apoptosis of pufferfish blood cells. Total blood cell count, reactive oxygen species (ROS) production, cytoplasmic free-Ca2+ (cf-Ca2+) concentration, nitric oxide (NO) production, apoptotic cell ratio and the transcription levels of caspase-3 in the pufferfish blood cells were determined after A. hydrophila infection. Results showed that A. hydrophila infection significantly depressed the total blood cell count, and significantly increased ROS production, cf-Ca2+ concentration, NO production and apoptotic cell ratio. The transcription levels of caspase-3 increased significantly after A. hydrophila infection. Taken together, our results suggest that A. hydrophila infection alters ROS, cf-Ca2+, NO levels, and active caspase-3, which lead to cell apoptosis
The Efficacy of Chamomile (Matricaria chamomilla l.) Oil as a Promising Anaesthetic Agent for Two Freshwater Aquarium Fish Species
Get PDFThe efficacy of anesthetic chamomile oil (from Matricaria chamomilla L.) was evaluated in two freshwater aquarium fish species, Electric Blue Hap (Sciaenochromis fryeri) and Yellow Princess (Labidochromis caeruleus). Fish were exposed to ten concentrations of anesthetic (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0 ml/L). The optimal doses identified as 0.6 ml/L for deep anesthesia (A5) for both two species. The minimal sedative dose at the stage of loss of equilibrium (A3) was found to be 0.3 ml/L. The induction time generally decreased significantly with increasing concentrations of chamomile oil for all treatment groups. Recovery time tended to increase with increased chamomile oil at concentrations lower than 0.7 ml/L, but after this concentration it decreased. Chamomile oil proved to be effective as an anesthetic for both ornamental fish species. These findings suggest that chamomile oil is a promising anesthetic agent for aquaculture. However, further studies should be focused on species based investigations on the effect of temperature, transfer of fish, and their effect on antioxidant and oxidant status, in order to gather further information
Visitor Statistics (Fourth Quarter 2016)
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Institute for Research, Extension, and Training in Agriculture's South Pacific agricultural news
No full textMonthly newsletter of the Institute for Research, Extension and Training in Agriculture and School of Agriculture, located in Apia, Samoa
Establishment of a Multiplex PCR Assay to Detect Five Major Freshwater Bacteria
Get PDFA multiplex polymerase chain reaction (mPCR) method for simultaneous detection of Aeromonas hydrophila, Streptococcus agalactiae, Klebsiella pneumoniae, Edwardsiella tarda, and E. ictalur was developed to rapidly and accurately identify the five most common bacteria that infect aquatic animals. The expected amplicons for ahe2 gene of A. hydrophila, cpsE gene of S. agalactiae, khe gene of K. pneumoniae, mukF gene of E.tarda, and the serC gene of E. ictaluri were 853 bp, 685 bp, 428 bp, 356 bp, and 124 bp, respectively. In the single PCR assays, the minimum detectable DNA contents were 13.2 pg for A. hydrophila, 27.4 pg for S. agalactiae, 1.95 pg for K. pneumoniae, 1.63 pg for E. tarda, 1.02 pg for E. ictalur. The detection limits of the multiplex PCR were 0.66 ng, 1.91 ng, 0.68 ng, 0.41 ng, 0.71 ng for A. hydrophila, S. agalactiae, K. pneumoniae, E. tarda and E. ictalur, respectively. The established multiplex PCR is significant for the rapid detection of common pathogenic bacteria of aquatic animals and provides the basis for the diagnosis of fish diseases
Effect of Dietary Soybean Lecithin and Cholesterol on Growth, Antioxidant Status and Fatty Acid Composition of Juvenile Swimming Crab, Portunus trituberculatus
Get PDFAn 8-week feeding trial was conducted to evaluate the effects of dietary soybean lecithin and cholesterol levels on the growth, antioxidant status and fatty acid composition in the tissues of swimming crab (Portunus trituberculatus). Eight experimental diets were formulated to contain four levels of soybean lecithin (0, 10, 20 and 40 g kg-1 of diet) and two cholesterol levels (0 and 6 g kg-1 of diet). Each diet was randomly assigned to triplicate groups of 60 swimming crabs (approximately 3.70 ± 0.03 g). The highest weight gain (WG), specific growth rate (SGR) and molting frequency (MF) were observed with crabs fed the diet supplemented with 40 g kg-1 lecithin and 6 g kg-1 cholesterol. Crabs fed the diet without lecithin and cholesterol had a lower WG and SGR as compared to those fed the other diets. Cholesterol, triglyceride and glucose concentrations in the serum were significantly influenced by soybean lecithin and cholesterol levels. Crabs fed the diets containing 40 g kg-1 lecithin with or without cholesterol supplementation had lower malondialdehyde (MDA) in the hepatopancreas as compared to those fed the other diets. Moreover, glutathione peroxidase (GPx) and lysozyme activities in the hepatopancreas were significantly affected by the dietary soybean lecithin and cholesterol levels. Highly unsaturated fatty acids (HUFAs) in the muscles were not significantly influenced by the dietary soybean lecithin and cholesterol levels. The concentrations of total HUFA in hepatopancreas were significantly influenced by the dietary soybean lecithin and cholesterol levels. In conclusion, interaction between dietary soybean lecithin and cholesterol affects growth performance, feed utilization and fatty acids in the hepatopancreas, dietary soybean lecithin and cholesterol supplementation enhance lipid transportation and metabolis
Dietary Protein Requirement of Juvenile Ide, Leuciscus idus in Relation to Growth Performance, Whole-body Composition and Plasma Parameters
Get PDFA 60-day feeding trial was conducted to determine the dietary protein requirements of juvenile ide, Leuciscus idus. Six iso-energetic experimental diets were formulated to contain graded protein levels ranging from 26.5% to 50.9% of dry diet. At the end of feeding trial, final weight (FW), weight gain (WG), and specific growth rate (SGR) increased significantly with increasing dietary protein levels up to 36.4%, and thereafter decreased with further increase of dietary protein levels (P0.05). Plasma protein content was not significantly affected by dietary protein levels (P>0.05), while plasma triglyceride and glucose concentrations were decreased significantly with increasing dietary protein levels (P<0.05). The highest aspartic transaminase activity was observed in fish fed diet 26.5% protein, and the lowest value was observed in 36.4% protein group (P<0.05). Based on SGR and FCR, the dietary protein requirement of juvenile ide was determined to be 36.9%-37.7% of dry diet. Dietary methionine and lysine levels for optimal growth was calculated to be 0.83% and 2.25% of dry diet, respectively
Effects of Different Levels of Dietary Surfactin Supplementation on Intestinal Morphology, and Intestinal Microflora of Growth Retarded Marbled Eel Juveniles (Anguilla marmaorata)
Get PDFThis 70 day trial was conducted to investigate the effects of surfactin on intestinal morphology and intestinal microflora of growth retarded marbled eels (Anguilla marmorata). A total of six hundred and forty marbled eels at elver stage were randomly allocated to 4 treatment groups on the basis of body weight. There were 4 replicate tanks in each treatment group with 40 fish per tank. Four diets were formulated with four levels of dietary surfactin: 0, 25, 50, and 100 mg/kg, respectively. Fish were fed twice daily to apparent satiation for 70 days. Retarded marbled eels fed diets with surfactin supplementation had enhanced mucosa folds in their intestines (P0.05). Results of the present study indicate that surfactin improves intestinal function in retarded elvers of marbled eels