Now showing items 1-4 of 4

    • Article

      Effects of dietary l-tryptophan on the agonistic behavior, growth and survival of juvenile mud crab Scylla serrata 

      JLQ Laranja Jr., ET Quinitio, MR Catacutan & RM Coloso - Aquaculture, 2010 - Elsevier
      The reduction of the survival of mud crab during culture has been largely attributed to aggressive encounters and cannibalism. In some crustaceans, suppressed aggression is linked to increased concentration of circulating and brain serotonin (5-hydroxytryptamine, 5-HT). Likewise, tryptophan (TRP), a precursor of 5-HT is reported to suppress the aggression and improve the survival of some cultured fish through dietary supplementation. We investigated the effects of feeding formulated diet with different TRP levels (0.32% as control, 0.5%, 0.75% and 1% of dry diet) on the agonistic behavior, growth and survival of juvenile mud crab Scylla serrata. Mud crabs were individually stocked and fed the experimental diets for 4 weeks before they were set to a one hour fight experiment. The fights were recorded using a video camera and the aggressiveness of the crabs was quantified. Hemolymph was sampled after 15 and 30 days of feeding (resting) and right after the fight to measure circulating 5-HT concentration. Higher TRP levels suppressed the aggressiveness of mud crab in a dose dependent manner. The intensity and frequency of attacks were both significantly lower (P < 0.05) in those given diets containing 0.75% and 1% TRP as compared with the control. Serotonin-ELISA assay revealed that 5-HT levels in the hemolymph before the fight (after 15 and 30 days; resting) were not significantly different between treatments. However after the fight, 5-HT concentration was significantly higher in TRP-supplemented mud crabs as compared with the control (0.5% = P < 0.05; 0.75% and 1% = P < 0.01). Furthermore, mud crabs (0.16 g BW) were reared in 0.40 m2 circular tanks at 20 crabs/tank and fed the experimental diets for 30 days to determine growth and survival. Survival was higher in TRP-supplemented mud crabs (0.5% = 35%, 0.75% = 33.33%, 1% = 35%) as compared with the control (18.33%). However, daily growth gain (DRG), relative growth rate (RGR) and specific growth rate (SGR) were reduced in TRP-supplemented groups than with the control group. In conclusion, the data shows that the aggressive behavior of juvenile mud crab can be suppressed by supplementation of L-TRP. The survival of juvenile mud crab can be improved by increasing the level of TRP to 0.5%–1%. However, higher TRP levels may affect growth of mud crab. TRP supplementation resulted to a significant increase of 5-HT concentration in the hemolymph which was clearly observed after the fight suggesting that 5-HT plays an important role in suppressing the agonistic behavior of mud crab during aggressive encounters.
    • Article

      Poly-beta-hydroxybutyrate-enriched Artemia sp. for giant tiger prawn Penaeus monodon larviculture 

      G Ludevese-Pascual, JLQ Laranja, EC Amar, P Sorgeloos, P Bossier & P De Schryver - Aquaculture Nutrition, 2017 - John Wiley and Sons
      The beneficial effects of PHB as supplement for giant tiger prawn Penaeus monodon postlarvae using a short-term enrichment strategy via Artemia were examined. The effects of co-supplementing with a lipid emulsion were also evaluated to determine whether it yielded an additional benefit. Results on the average weight and larval development were not significantly different among postlarvae fed the different dietary treatments, indicating that PHB supplementation could not be used to stimulate growth in P. monodon postlarvae while such positive results have been reported in other aquaculture species. Nonetheless, significantly higher survival was obtained in postlarvae fed PHB-enriched Artemia irrespective of lipid enrichment. In addition, PHB increased the survival of the postlarvae after exposure to a lethal dose of ammonia. Lipid supplementation nullified this effect. The cumulative mortality of postlarvae subjected to a sublethal concentration of ammonia for 24 h and subsequent exposure to pathogenic Vibrio campbelli showed that PHB but not lipids could effectively enhance the resistance of the postlarvae. Co-supplementing lipids even significantly decreased this outcome. Our study indicates that PHB supplementation increases the quality of larval P. monodon and their chance of surviving under adverse environmental conditions. The short-term co-supplementation with lipid emulsion did not add to these effects.
    • Article

      Poly-β-hydroxybutyrate (PHB) accumulating Bacillus spp. improve the survival, growth and robustness of Penaeus monodon (Fabricius, 1798) postlarvae 

      JLQ Laranja, GL Ludevese-Pascual, EC Amar, P Sorgeloos, P Bossier & P De Schryver - Veterinary Microbiology, 2014 - Elsevier
      Low larval survival resulting from suboptimal culture conditions and luminous vibriosis poses a major problem for the larviculture of penaeid shrimp. In this study, a poly-β-hydroxybutyrate (PHB) accumulating mixed bacterial culture (mBC; 48.5% PHB on cell dry weight) and two PHB accumulating bacterial isolates, Bacillus sp. JL47 (54.7% PHB on cell dry weight) and Bacillus sp. JL1 (45.5% PHB on cell dry weight), were obtained from a Philippine shrimp culture pond and investigated for their capacity to improve growth, survival and robustness of Penaeus monodon postlarvae (PL). Shrimp PL1 and shrimp PL30 were provided with the PHB containing bacterial cultures in the feed for 30 days followed by, respectively, a challenge with pathogenic Vibrio campbellii and exposure to a lethal dose of ammonia. Prior to the pathogenic challenge or ammonia stress, growth and survival were higher for shrimp receiving the PHB accumulating bacteria as compared to shrimp receiving diets without bacterial additions. After exposure to the pathogenic challenge the shrimp fed PHB accumulating bacteria showed a higher survival as compared to non-treated shrimp, suggesting an increase in robustness for the shrimp. Similar effects were observed when shrimp PL30 were provided with the PHB accumulating bacterial cultures during a challenge with pathogenic V. campbellii through the water. The survival of shrimp exposed to lethal ammonia stress showed no significant difference between PHB accumulating bacteria-fed shrimp and non-PHB treated shrimp. The data illustrate that bacilli capable of accumulating PHB can provide beneficial effects to P. monodon post-larvae during culture in terms of growth performance, survival and resistance against pathogenic infection and ammonia stress. Further investigations are required to verify the PHB effect of the bacterial cultures on the shrimp.
    • Article

      A probiotic Bacillus strain containing amorphous poly-beta-hydroxybutyrate (PHB) stimulates the innate immune response of Penaeus monodon postlarvae 

      JLQ Laranja, EC Amar, GL Ludevese-Pascual, Y Niu, MJ Geaga, P De Schryver & P Bossier - Fish and Shellfish Immunology, 2017 - Elsevier
      In this study, the PHB-accumulating Bacillus sp. JL47 strain (capable of accumulating 55% PHB on cell dry weight) was investigated for its effects on the immune response of giant tiger shrimp (Penaeus monodon) postlarvae (PL) before and after the Vibrio campbellii challenge. Briefly, shrimp PL were cultured and fed with Artemia nauplii enriched with Bacillus sp. JL47. Shrimp receiving the Artemia nauplii without JL47 enrichment were used as control. After 15 days of feeding, the shrimp were challenged with pathogenic V. campbellii LMG 21363 at 106 cells mL-1 by immersion. Relative expression of the immune related genes encoding for prophenoloxidase (proPO), transglutaminase (TGase) and heat shock protein 70 (Hsp70) in the shrimp were measured before (0 h) and after (3, 6, 9, 12, 24 h) the Vibrio challenge by quantitative real-time PCR using β-actin as the reference gene. The expressions of TGase and proPO were significantly up-regulated (p < 0.05) within 9 h and 12 h, respectively after challenge in shrimp receiving the Bacillus sp. JL47 as compared to the challenged and non-challenged controls. Hsp70 expression was significantly increased (p < 0.05) at 3 h post-challenge in all challenged shrimp. Interestingly, proPO and TGase genes were significantly up-regulated (p < 0.05) in Bacillus sp. JL47 treated shrimp even before the Vibrio challenge was applied. No up-regulation in the Hsp70 gene, however, was observed under these conditions. The data suggest that the protective effect of the PHB-accumulating Bacillus sp. JL47 in shrimp was due to its capacity to stimulate the innate immune related genes of the shrimp, specifically the proPO and TGase genes. The application of probiotic Bacillus species, capable of accumulating a significant amount of PHB, is suggested as potential immunostimulatory strategy for aquaculture.