Now showing items 1-20 of 20

    • Article

      Antibacterial properties of the microalgae Chaetoceros calcitrans 

      EB Seraspe, BF Ticar, MJ Formacion, IG Pahila, MR de la Peña & EC Amar - Asian Fisheries Science, 2012 - Asian Fisheries Society
      The antibacterial properties of the microalgae Chaetoceros calcitrans were assessed. Samples of C. calcitrans were first extracted in methanol, and then in different organic solvents of increasing polarity, n-hexane (n-Hex), dichloromethane (DCM) and ethyl acetate (EA) by liquid-liquid extraction. Solvent extracts were screened for antibacterial activity against four species of bacteria: Gram positive, Staphylococcus aureus and Bacillus subtilis; and Gram negative, Escherichia coli and Vibrio harveyi, with Amoxicillin as positive control, N-Hex extract, with significantly lower antibacterial activity than Amoxicillin, showed significantly higher activity than DCM and EA extracts, and least in methanolic extract. High antibacterial activity of n-Hex extract against all the microorganisms indicates that the bioactive components could be non-polar since the activity decreased as the solvent became more polar like methanol, and finally lost in aqueous extract. Results also showed that the extracts have a broad spectrum activity. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of all solvent extracts on all microorganisms tested ranged from 125 to 500 μg.mL-1. Partial purification and characterisation of the extracts confirmed the antibacterial activity in the non-polar fraction, which could be terpenes. The results suggest a good prospect in using C. calcitrans against Vibrio and other bacterial species.
    • Article

      Dietary onion and ginger enhance growth, hemato-immunological responses, and disease resistance in brown-marbled grouper, Epinephelus fuscoguttatus. 

      MJS Apines-Amar, EC Amar, JP Faisan Jr., RV Pakingking Jr. & S Satoh - Aquaculture, Aquarium, Conservation and Legislation, 2012 - Bioflux
      A 12-week (September to December 2009) feeding trial was conducted to evaluate theimmunostimulatory effects of different substances administered orally through the diet in the brown-marbled grouper, Epinephelus fuscoguttatus. Five experimental diets containing either onion, ginger, β–glucan, or vitamin C and a control diet (without immunostimulants) were fed to the fish weighing about 44 g for 12 weeks. Onion-fed fish showed significantly increased weight gain, hematocrit, and total Ig compared to the control group; however, leukocyte differential count and ROS production were unaffected. Ginger-fed fish likewise significantly increased total Ig, ROS production and lysozyme activity. However, it did not affect growth and hematocrit value. β-glucan significantly increased growth and total Ig but had no effect on the other parameters. Vitamin C significantly increased hematocrit, total Ig and ROS production but did not increase growth. Upon challenge with a bacterial pathogen Vibrio harveyi, mortality was significantly reduced in the onion, ginger and vitamin C-fed fish but not in the β–glucan-fed fish. This study demonstrated that onion and ginger could positively affect the innate immune responses and protect grouper against Vibrio harveyi infection.
    • Article

      Enhancement of innate immunity in rainbow trout (Oncorhynchus mykiss Walbaum) associated with dietary intake of carotenoids from natural products 

      EC Amar, V Kiron, S Satoh & T Watanabe - Fish and Shellfish Immunology, 2004 - Elsevier
      The effects of orally administered carotenoids from natural sources on the non-specific defense mechanisms of rainbow trout were evaluated in a nine-week feeding trial. Fish were fed four diets containing either β-carotene or astaxanthin at 100 and 200 mg kg−1 from the marine algae Dunaliella salina and red yeast Phaffia rhodozyma, respectively, and a control diet containing no supplemented carotenoids. Specific growth rate and feed:gain ratio were not affected by dietary carotenoid supplementation. Among the humoral factors, serum alternative complement activity increased significantly in all carotenoid supplemented groups when compared to the control. On the other hand, serum lysozyme activity increased in the Dunaliella> group but not in the Phaffia group, whereas plasma total immunoglobulin levels were not altered by the feeding treatments. As for the cellular responses, the superoxide anion production from the head kidney remained unchanged while the phagocytic rate and index in all supplemented groups were significantly higher than those of the control. These findings demonstrate that dietary carotenoids from both D. salina and P. rhodozyma can modulate some of the innate defense mechanisms in rainbow trout.
    • Article

      Evaluation of dietary freeze-dried Chaetoceros calcitrans supplementation to control Vibrio harveyi infection on Penaeus monodon juvenile 

      EB Seraspe, S Gabotero, MR de la Peña, IG Pahila & EC Amar - Aquaculture, 2014 - Elsevier
      Effects of supplementation of diets with freeze-dried Chaetoceros calcitrans to control Vibrio harveyi infection are evaluated through immune responses, and disease resistance of juvenile Penaeus monodon. Total lipid and fatty acid profile of Chaetoceros calcitrans is also analyzed. A challenge infection with 107 cfu/mL concentration of Vibrio harveyi is intramuscularly injected to juvenile Penaeus monodon after 45 days of feeding of diets supplemented with 15 g/kg and 30 g/kg dried Chaetoceros calcitrans. The use of dried Chaetoceros calcitrans is compared with that of ß-1,3 glucan Curdlan, a commercial immune enhancer. Incorporation of 30 g/kg Chaetoceros calcitrans in the diet enhances the immune system of shrimp as effected by high prophenoloxidase activity and plasma protein concentration and is better compared to the commercially available Curdlan. Chaetoceros calcitrans also contains polyunsaturated fatty acids (PUFAs) such as linolenic acid and eicosapentanoic acid (EPA) which are responsible for its antibacterial action against Vibrio harveyi. All these biological activities of Chaetoceros calcitrans add up to increase resistance of the juvenile Penaeus monodon to vibriosis as shown by its high survival rate from the challenge infection with Vibrio harveyi. Therefore, it is worthwhile to use Chaetoceros calcitrans as supplementary feed. Its effect in increasing the immune competence coupled with its antibacterial action, make the shrimp resistant to luminous vibriosis that continues to affect the industry, thereby augmenting aquaculture production.
    • Article

      Growth, plasma cortisol, liver and kidney histology, and resistance to vibriosis in brown-marbled grouper, Epinephelus fuscoguttatus fed onion and ginger 

      MJS Apines-Amar, EC Amar & JP Faisan Jr. - Aquaculture, Aquarium, Conservation and Legislation, 2013 - Bioflux
      The health-promoting effects of dietary onion and ginger were studied in brown marbled grouper, Epinephelus fuscoguttatus. An eight-week feeding trial was conducted to evaluate the effects of dietary onion and ginger on growth, cortisol levels, histology and disease resistance in the fish. Five experimental diets were formulated to contain either onion (2%), ginger (2%), β-glucan (1%) or vitamin C (3%) and a control diet (without immunostimulants). Each diet was fed to triplicate groups of fish with an average weight of 10.85±0.69 g. Fish supplemented with either of the immunostimulants exhibited a significantly higher growth compared to the control group. Specific growth rate (SGR) and feed conversion efficiency (FCE) were significantly higher in the onion and ginger-supplemented fish than the control. Cortisol level was higher in the control compared to the immunostimulant-fed groups with onion and ginger-fed fish showing significantly lower cortisol levels. When experimentally infected with Vibrio harveyi, fish fed onion or ginger exhibited significantly reduced mortality when compared with the control and β-glucan, but not when compared with the vitamin C-fed group. Liver sections sampled 4 days postinfection showed no remarkable pathology except for the slight reduction in glycogen granules in the supplement-fed fish. The liver of non-supplemented infected fish showed necrosis, fatty globule deposition, vacuolation, and presence of short rod-shaped bacteria. Kidney sections in the supplemented groups, likewise, did not show significant pathology similar to the uninfected control, whereas those of infected control fish showed necrosis of the tubules and glomeruli resulting in severely altered morphology of the tissues and presence of bacteria in the necrotic areas. As a result of circumventing tissue damage, wound healing was faster in fish supplemented with ginger, onion, and vitamin C compared to the β-glucan and the control groups. This study showed the benefits of onion and ginger in promoting growth and alleviating stress and severity of vibriosis in grouper.
    • Conference paper

      Healthy and wholesome aquaculture. 

      CR Lavilla-Pitogo, MR Catacutan & EC Amar - In BO Acosta, RM Coloso, EGT de Jesus-Ayson & JD Toledo (Eds.), Sustainable aquaculture development for food security in Southeast Asia towards 2020. Proceedings of the Regional Technical Consultation on Sustainable Aquaculture Development in Southeast Asia Towards 2020, 2011 - SEAFDEC Aquaculture Department
      The concept of healthy and wholesome aquaculture as a holistic approach to sustainable food-fish production has gained more relevance since it was discussed in a similar SEAFDEC forum almost a decade ago. Similar concepts to optimize yield from various production systems with least impact on the environment include Best Management and Good Aquaculture Practices. The three prioritized areas of disease control, food safety and environmental integrity that were identified during the first Fish for the People Conference in 2001 guided the research and development strategies for the past decade. The dynamic nature of aquaculture, however, also paved the way for major species introductions that changed the regional production scenario altogether.

      An important component of effective disease prevention and control is the development of diagnostic techniques. In response to recommendations made in 200I during the first Fish for the People Conference, diagnostic procedures have been harmonized, classified according to levels of complexity, and a few have been translated into techniques for pond-side application. Disease surveillance and reporting have been enhanced in most countries and the awareness about transboundary diseases has been heightened. The region, however, still has a lot to learn about bringing in new and exotic species and their accompanying threat of disease introduction. The past decade has seen the replacement of Penaeus monodon by P. vannamei as the major shrimp species in culture that has resulted in the introduction of major viral diseases like infectious myonecrosis virus (lMNV) and taura syndrome virus (TSV). The first outbreak of koi herpes virus (KHV) occurred in Indonesia in 2002 and Japan in 2003, and the disease continues to affect the koi and common carp industry in some countries in Asia (Lavilla-Pitogo & Nagasawa 2004). Various parasites have become major threats to sustainable marine fish production. Thus, controlling the spread of important pathogens through the introduction of exotic fish species, or the transfer of infected fish to another facility or to wild habitat remains a major problem.

      The development of specific-pathogen-free stocks and the corresponding implementation of biosecurity measures are the most significant advancements to control viral diseases each a prerequisite of the other to guarantee successful production. The vastness of land-based aquaculture systems, however, makes the cost of implementing biosecurity prohibitive, thus, there remains the need for additional health implements to boost fish health like vaccines, immunostimulants, probiotics, chemotherapeutics and disinfectants. Although major research efforts have been devoted to develop such products, satisfactory field test results are wanting for most of them. The issue on unwanted residues in marketable fish products and the fate of antimicrobials and chemicals in the environment are the major deterrents for their widespread application in aquaculture. Furthermore, the lack of fish health professionals that are qualified to prescribe drugs and chemotherapeutants in aquaculture is an issue that needs urgent action in the region.

      The clamor for aquaculture to reduce its dependence on fish meal as the source of protein in artificial feeds has led to numerous studies about fishmeal substitutes. The search for suitable alternative fish feed ingredients may now require a combination of biochemical engineering and manufacturing to enhance the nutritional composition of non-traditional protein sources. Fishmeal substitutes and other feed ingredients that will not compromise fish health and drastically alter carcass composition needs to be developed. Since proper feed management is a key component for farm profitability and sustainability as well as in the reduction of environmental pollution, extension and technology transfer should continue so that various stakeholders will be informed of their responsibility. Efforts to improve fish feed development should continue keeping in mind that feed is a key determinant of fish health.

      For aquaculture to meet the target production to supply the protein requirements of a burgeoning global population, production systems should further emphasize the key components of keeping diseases under control, producing fish that pass food safety standards, and maintaining the integrity of the culture system and its environment. In various countries, supportive efforts are in the form of certification, accreditation and compliance of aquaculture facilities with standards. However, aquaculture, being a relatively new sector in the food production industry, needs to harmonize its efforts with other common resource users.
    • Article

      Improved resistance against White Spot Virus (WSV) infection in tiger shrimp, Penaeus monodon by combined supplementation of peptidoglycan and mannan oligosaccharide (MOS) 

      MJS Apines-Amar, KGS Andrino, EC Amar, RE Cadiz & VL Corre Jr. - Extreme Life, Biospeology and Astrobiology, 2014 - Bioflux Society
      An eight-week feeding trial was conducted to evaluate the effects of combined supplementation of peptidoglycan and mannan oligosaccharide (MOS) in tiger shrimp, Penaeus monodon. Tiger shrimp (0.29 ± 0.02 g) were fed diets supplemented with different levels of peptidoglycan + (MOS) as immunostimulants for six (6) and eight (8) weeks. Four (4) experimental diets were formulated to contain 0, 0.1, 0.2, and 0.4% peptidoglycan + MOS. The feeding trial was conducted in 250 L capacity concrete circular tanks (replicated four (4) times) with 20 shrimp per tank. Growth, survival, respiratory burst activity, total hemocyte count (THC), and in vivo resistance to WSV infection were evaluated. Weight gain of the shrimp was significantly higher in the immunostimulant-fed groups compared to the control. However, different levels of the immunostimulants did not differ in their effect on the the growth of the shrimp. On the other hand, respiratory burst activity and total haemocyte count (THC) were significantly higher in the group supplemented with 0.2% peptidoglycan + MOS than the rest of the treatments. Likewise, survival after infection with White Spot Virus (WSV) was significantly increased in the 0.2% peptidoglycan + MOS compared to the other groups. The present results demonstrated that using peptidoglycan and MOS together at 0.2% of the diet improves growth, activates immune responses such as respiratory burst activity and THC in P. monodon and give better protection to the shrimp against WSV infection.
    • Article

      Induction of immunity and resistance to white spot syndrome virus (WSSV) in shrimp Penaeus monodon (Fabricius) by synthetic oligodeoxynucleotide and bacterial DNA 

      EC Amar & JP Faisan Jr. - Philippine Agricultural Scientist, 2012 - University of the Philippines Los Baños
      Shrimps like all invertebrates are believed to lack true adaptive immunity but recent evidence indicate that they can be protected against pathogenic organisms by priming their immune system with immunostimulatory substances. Here, we describe results of investigation aimed to strengthen shrimp immunity as a preventive strategy against white spot syndrome virus (WSSV) infection. Oligodeoxynucleotides (ODNs) with and without Cytosine-Guanine (CpG) motifs, and Vibrio harveyi genomic DNA (VHD) were administered by intramuscular injection and shrimp responses were assessed by ex vivo assays and experimental infection trials. Results showed that CpG ODN significantly increased ex-vivo immunity indices such as total hemocyte count (THC), plasma agglutination titer (PAT) and hemocyte lysate agglutination titer (HLAT). VHD significantly increased immune indices such as THC, plasma total protein (PTP) and HLAT. Reverse (GpC) motifs increased THC only. At a lower viral challenge dose, both CpG and GpC motifs, and VHD, were able to reduce shrimp mortality significantly but only CpG and VHD did so at a higher challenge dose. Strengthening shrimp immunity by the use of immunostimulatory nucleotides and bacterial genomic DNA could be a feasible preventive approach in the management of WSSV infections in shrimp.
    • Article

      Influence of various dietary synthetic carotenoids on bio-defence mechanisms in rainbow trout, Oncorhynchus mykiss (Walbaum) 

      EC Amar, V Kiron, S Satoh & T Watanabe - Aquaculture Research, 2001 - Wiley-Blackwell
      This study examined the influence of different carotenoids on growth and some immune indices in rainbow trout. Six semipurified casein-based diets were formulated to contain one of three different carotenoids: astaxanthin, canthaxanthin and β-carotene, at 100 mg kg−1, each of them with vitamins A, C and E either added or omitted. The two control diets contained no carotenoids and were either with or without the vitamins. Rainbow trout weighing about 140 g were fed the diets for 9 weeks. Specific growth rate, feed:gain ratio and nonspecific immune parameters were determined. Growth and feed conversion were similar among the groups. Immune parameters like production of reactive oxygen species by head kidney leukocytes and plasma total immunoglobulin levels did not vary with the treatment. Serum complement activity in both β-carotene groups and the vitamin-containing astaxanthin group were significantly higher than both the control fish. Serum lysozyme activity in the vitamin-containing β-carotene and astaxanthin groups were significantly different from both control groups. Phagocytic activity was also high in the vitamin-containing β-carotene and astaxanthin groups compared with the controls. For phagocytic index, in addition to the foregoing groups, the vitamin-containing canthaxanthin group gave better results compared with the controls. The vitamin-containing astaxanthin and β-carotene groups also exhibited better nonspecific cytotoxicity for the peripheral blood lymphocytes at all effector-to-target ratios. Thus, among the carotenoids studied, β-carotene and astaxanthin elevated humoral factors such as serum complement and lysozyme activity, as well as cellular factors such as phagocytosis and nonspecific cytotoxicity. In the presence of the vitamins the carotenoids exerted a greater influence on the bio-defense mechanisms of rainbow trout.
    • Book

      The Malalison experience: empowering an island community in west central Philippines 

      RF Agbayani, CL Marte, DB Baticados, EC Amar & MT Castaños - 2009 - Aquaculture Department, Southeast Asian Fisheries Development Center
      A 64-page booklet that describes SEAFDEC/AQD’s community fishery resources management project from 1991 to 1998 with a post project assessment in 2009.
    • Article

      Mortality of pond-cultured Litopenaeus vannamei associated with acute hepatopancreatic necrosis disease (AHPND) and white spot syndrome virus (WSSV) infection in the Philippines 

      LD de la Peña, NAR Cabillon, EC Amar, DD Catedral, RC Usero, JP Faisan Jr., JI Arboleda, WD Monotilla, AT Calpe, DD Fernandez & CP Saloma - Fish Pathology, 2017 - Japanese Society of Fish Pathology
      Mortalities of up to 60% were observed in pond-cultured Litopenaeus vannamei in Bohol, Philippines. Histopathological examination revealed typical acute hepatopancreatic necrosis disease (AHPND) pathology. PCR test generated 1,269 bp and 230 bp amplicons confirmative for the toxin-producing AHPND strain of Vibrio parahaemolyticus among shrimp sampled from eight ponds. The same samples were subjected to PCR analyses for the presence of other viruses, namely WSSV, IHHNV, IMNV, and TSV. The samples were negative for the viruses except WSSV, which was detected after one-step PCR in six out of eight ponds. These results suggested that shrimp were infected dually with AHPND V. parahaemolyticus and WSSV.
    • 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.
    • Article

      Resistance of rainbow trout Oncorhynchus mykiss to infectious hematopoietic necrosis virus (IHNV) experimental infection following ingestion of natural and synthetic carotenoids 

      EC Amar, T Akutsu, S Satoh & T Watanabe - Aquaculture, 2012 - Elsevier
      Further to previous studies showing modulation of innate immune responses by dietary carotenoids, an experiment was conducted to examine the resistance to a viral pathogen in rainbow trout after oral ingestion of synthetic or natural carotenoids. Rainbow trout fry weighing 0.11 g on average (n = 30) were fed casein-based semi-purified diets supplemented with 100 mg carotenoids kg− 1 diet for 6 weeks. The synthetic sources tested were pure β-carotene, astaxanthin, and canthaxanthin, whereas the natural sources were Dunaliella salina, Phaffia rhodozyma, Tagetes erecta, and Capsicum annuum. No significant differences (P > 0.05) in growth and feed performance were found among the groups after 6 weeks of feeding. Subsequently, fish were challenged by immersion in two concentrations (2 × 103 and 2 × 104 TCID50 ml− 1) of a virulent strain of infectious hematopoietic necrosis virus (IHNV) and cumulative mortalities were recorded over a 30-day period. No significant differences in survival (P > 0.05) were found among the groups when challenged with the high viral dose. However, at the lower viral dose, mortality was markedly reduced in fish fed astaxanthin (22%). Consequently, this group exhibited the highest relative percent survival (RPS) of 58%, which was significantly different from the control (P < 0.05). Rainbow trout fed D. salina and T. erecta among the natural sources, had reduced mortality rates and elevated RPS that, nonetheless, did not significantly differ from the control. This study highlights the influence of carotenoids, particularly astaxanthin, in maintaining fish health and disease resistance.
    • Article

      Small-scale fisheries of coral reefs and the need for community-based resource management in Malalison Island, Philippines 

      EC Amar, RMT Cheong & MVT Cheong - Fisheries Research, 1996 - Elsevier
      Fish landings in Malalison Island in the west central Philippines were monitored from February 1991 to January 1992 to determine the types of fishing gear employed, the predominant species caught, the catch per unit effort (CPUE), and the yield from the coral reefs. Fishing was monitored only during the spring tide periods, after a preliminary sampling showed no significant differences among four lunar phases. A total of 494 fishing operations was recorded. CPUE (kg per fisher h−1) by gear was 1.1 for spear guns, 1.4 for spear guns with compressor, 0.4 for set gill nets, 2.4 for drive-in gill nets, 1.2 for drift gill nets, and 0.7 for hook-and-lines. The CPUEs of Malalison gears are similar to those of other coral reef fisheries. Dominant species caught were fusiliers and surgeonfishes by gill net. surgeonfishes by spear gun, and snappers and groupers by hook-and-line. The fish yield from the Malalison coral reefs was estimated to be 5.8 t km−2 year−1, which is low, and similar to overexploited. reefs in the Philippines and elsewhere. Live coral cover averages 35% in Malalison. Reef degradation, high fishing effort, low yields, and the poverty of the fishing community suggest ‘Malthusian over-fishing’. Community based management and resource enhancement are being initiated by the SEAF-DEC Aquaculture Department to protect and sustain the fishery and improve the economy in Malalison Island.
    • Article

      Subtracted transcriptome profile of tiger shrimp (Penaeus monodon) that survived WSSV challenge 

      BA Maralit, MFH Ventolero, MBB Maningas, EC Amar & MD Santos - Dataset Papers in Science, 2014 - Hindawi Publishing Corporation
      There is increased interest in the development of virus-resistant or improved shrimp stock because production is currently hindered by outbreaks and limited understanding of shrimp defense. Recent advancement now allows for high-throughput molecular studies on shrimp immunity. We used next-generation sequencing (NGS) coupled with suppression subtractive hybridization (SSH) to generate a transcriptome database of genes from tiger shrimp that survived White spot syndrome virus (WSSV) challenge. A total of 9,597 unique sequences were uploaded to NCBI Sequence Read Archive with accession number SRR577080. Sixty-five unique sequences, 6% of the total, were homologous to genes of Penaeus monodon. Genes that were initially related to bacterial infection and environmental stress such as 14-3-3 gene, heat shock protein 90, and calreticulin were also found including a few full-length gene sequences. Initial analysis of the expression of some genes was done. Hemocyanin, ferritin, and fortilin-binding protein exhibited differential expression between survivor and control tiger shrimps. Furthermore, candidate microsatellite markers for brood stock selection were mined and tested. Four trinucleotide and one dinucleotide microsatellites were successfully amplified. The study highlights the advantage of the NGS platform coupled with SSH in terms of gene discovery and marker generation.
    • Article

      Surveillance of emerging fish viral pathogens in some Southeast Asian countries 

      G Lio-Po, E Amar, L de la Peña, ZG Orozco, J Faisan, V Suarnaba & DB Tubo - The Israeli Journal of Aquaculture-Bamidgeh, 2009 - Society of Israeli Aquaculture and Marine Biotechnology
      Preventing the transboundary movement of fish viral pathogens in a global environment requires active surveillance. This study examined the presence of three emerging viral pathogens among koi, common, grass, and silver carp in Cambodia, Lao PDR, Myanmar, Philippines, and Vietnam. The studied viruses included koi herpesvirus (KHV), spring viremia of carp virus (SVCV), and grass carp reovirus (GCRV). Detection methods consisted of virus isolation by cell culture, infection assay in naive fish, polymerase chain reaction (PCR), and reverse-transcriptase PCR (RT-PCR). Tissues were collected and pooled from 193 fish samples in Dec. 2004 to Feb. 2005, 406 in Sep. 2005 to Feb. 2006, and 1302 in Oct. 2006 to Feb. 2007. For cell culture, tissue filtrates were prepared from pooled spleens, kidneys, livers, and gills and inoculated onto koi fin (KF-1), grass carp kidney (GCK), and fat head minnow (FHM) cells. For infection assay, tissue filtrates were injected intraperitoneally to healthy, naive common carp. No virus was detected after three cell culture passages and the infection bioassays. One-step and nested-step PCR was used to detect KHV in gills of fish samples. One-step and semi-nested RT-PCR was used to detect SVCV and GCRV in the spleens, kidneys, and livers of fish samples. Samples from all three years from all five countries yielded negative results for all three viruses, indicating that KHV, SVCV, and GCRV were not present in these five countries during the period of the study although KHV outbreaks had been detected in Indonesia, Taiwan, Japan, Thailand, China, and Malaysia.
    • Article

      Temporal changes in innate immunity parameters, epinecidin gene expression, and mortality in orange-spotted grouper, Epinephelus coioides experimentally infected with a fish pathogen, Vibrio harveyi JML1 

      EC Amar, JP Faisan Jr., MJS Apines-Amar & RV Pakingking Jr. - Fish and Shellfish Immunology, 2017 - Elsevier
      Changes in innate immunity parameters and epinecidin mRNA transcript levels were examined to characterize the non-specific immune response of E. coioides to pathogenic V. harveyi JML1 isolated from affected cage-cultured fish. After fish had been injected with bacteria at a dose causing 30% mortality, blood and tissue samples were collected at 0, 6, 12, 24, 48, 72, 96, 120, and 240 h post-infection (hpi) for assessment of indices such as the oxidative burst (OB) and phagocytic index (PI) of head kidney cells, and lysozyme activity (LYS) and total immunoglobulin (Total Ig) levels of the plasma. The epinecidin mRNA transcript levels (EGE) from skin, gills, liver, kidney, and spleen tissues were also determined by gelbased RT-PCR. Lastly, daily mortality (DM), liver total bacterial load (TBC), and presumptive Vibrio count (TVC) were monitored up to 240 hpi. The results revealed that bacteria proliferated rapidly in fish tissue, reaching peak densities at 24 hpi for both TBC and TVC but was on a downward trend thereafter. The pattern in fish mortality closely correlated with TBC and TVC. Total Ig, OB, and PI in E. coioides were suppressed in the early part of infection when V. harveyi load was high but recovered and later increased as bacterial density declined. LYS and EGE were consistently high and their activities were not hampered by bacterial infection. The study demonstrated that V. harveyi JML1 interacts with E. coioides by transiently inhibiting some immune parameters resulting in mortalities. However, consistently high LYS, upregulated EGE, and resurgent PI, OB and Total Ig conferred resistance and subsequent recovery in the fish. The study provides new insights on the interaction between E. coioides and V. harveyi JML1 that can aid in formulating health management strategies for groupers. Further studies on prophylactic interventions to enhance the innate immune response in grouper during infection with V. harveyi JML1 are suggested.
    • Book chapter

      Use of immunostimulants in shrimp culture: An update 

      MJS Apines-Amar & EC Amar - In CMA Caipang, MBI Bacano-Maningas & FF Fagutao (Eds.), Biotechnological Advances in Shrimp Health Management in the Philippines, 2015 - Research Signpost
      Different approaches are used to prevent and control diseases in aquaculture. Immunostimulation is one method that is gaining popularity and is considered a promising development in aquaculture. Immunostimulants were found to be effective in enhancing parameters of non-specific immunity and resistance to diseases of fish and crustaceans. However, some issues raised on the use of immunostimulants pertains to the short-term nature of immune indices used during efficacy evaluation, possible detrimental effects during long-term administration, or self-damage due to unregulated production of immune effectors. Further testing in large-scale production units has been recommended. This chapter presents the various types and sources of immunostimulants commonly used in aquaculture and in shrimp culture in particular. The effects of each immunostimulant vary depending on its source, dose, route of administration, length of exposure, and the species to which it is administered.