Now showing items 1-9 of 9

    • Book chapter

      Early development and seed production of Asian seabass, Lates calcarifer 

      EG de Jesus-Ayson, FG Ayson & V Thepot - In DR Jerry (Ed.), Biology and Culture of Asian Seabass Lates Calcarifer, 2014 - CRC Press
      This Chapter outlines the characteristics of L. calcarifer eggs and larvae, the changes during embryonic and larval development, advances in seed production and at the same time highlights the relative ease in its mass production.
    • Article

      Expression and purification of a biologically active recombinant rabbitfish (Siganus guttatus) growth hormone 

      B Funkenstein, D Dyman, Z Lapidot, EG de Jesus-Ayson, A Gertler & FG Ayson - Aquaculture, 2005 - Elsevier
      Recombinant rabbitfish growth hormone (rfGH) protein was expressed in Escherichia coli, BL21(DE3) cells. The cDNA encoding the mature protein of rfGH was first cloned in pGEM-Teasy vector and then transferred to pET-3d expression vector. Expression in E. coli cells was then induced by IPTG (0.4 mM). Inclusion bodies (IB) containing the expressed protein were purified by treating bacterial cells pellet with lysozyme followed by repeated washings in cold water containing Triton X-100, sonication, and centrifugation. IB were then solubilized in 4.5 M urea, refolded at pH 11.3 in the presence of catalytic amounts of cysteine and purified by Q-Sepharose column. Gel filtration on Superdex column showed the purified protein to be a monomeric GH. Based on SDS–PAGE, the purity of the recombinant rfGH preparation is approximately 98%. The recombinant rfGH was tested for its biological activity both in vitro, by its ability to stimulate IGF-I mRNA expression in the liver, and in vivo, by its ability to accelerate growth in rabbitfish fry injected with the hormone. A significant increase in growth was observed in rabbitfish fry given the recombinant hormone. Polyclonal antibody raised against the native rfGH immunoreacted with the recombinant rfGH in Western blots and in ELISA, indicating the suitability of these reagents for future quantification of GH in rabbitfish plasma.
    • Article

      Gonadal response of juvenile protogynous grouper (Epinephelus fuscoguttatus) to long term recombinant follicle-stimulating hormone administration 

      P Palma, J Nocillado, J Superio, EGdJ Ayson, F Ayson, I Bar & A Elizur - Biology of Reproduction, 2018 - Oxford University Press
      The role of follicle stimulating hormone (FSH) in the gonadal development of protogynous hermaphroditic grouper (E. fuscoguttatus) was investigated. Recombinant giant grouper (E. lanceolatus) FSH (rggFSH) was produced in yeast. Its receptor binding capacity and steroidogenic potency were confirmed in vitro. Weekly injections of rggFSH to juvenile tiger grouper for 8 weeks (100 μg/kg body weight, BW) resulted in significantly larger and more advanced oocytes (cortical alveolar stage vs. primary growth stage in control). Sustained treatment with rggFSH (20 to 38 weeks at 200 μg/kg BW) resulted in significant reduction in gonad size, degeneration of oocytes and proliferation of spermatogonial cells, indicative of female to male sex change. Gene expression analysis showed that, while initiating female to male sex change, the rggFSH significantly suppressed the steroidogenic genes cyp11b, cyp19a1a and foxl2 which restrained the endogenous production of sex steroid hormones thus prevented the differentiation of spermatogonial cells. Expression profile of sex markers dmrt1, amh, figla and bmp15 suggests that the observed sex change was restricted at the initiation stage. Based on these results, we propose that the process of female to male sex change in the protogynous grouper is initiated by FSH, rather than sex steroids and likely involves steroid-independent pathway. The cortical alveolar stage in oocyte development is the critical point after which FSH-induced sex change is possible in grouper.
    • Book chapter

      Nursery and grow-out culture of Asian seabass, Lates calcarifer, in selected countries in Southeast Asia 

      FG Ayson, K Sugama, R Yashiro & EG de Jesus-Ayson - In DR Jerry (Ed.), Biology and Culture of Asian Seabass Lates Calcarifer, 2014 - CRC Press
      In this chapter, the practices of growing Asian seabass in nursery and grow-out culture systems in selected Southeast Asian countries like the Philippines, Thailand and Indonesia are described.
    • Article

      Protective immunity against viral nervous necrosis (VNN) in brown-marbled grouper (Epinephelus fuscogutattus) following vaccination with inactivated betanodavirus 

      R Pakingking Jr., NB Bautista, EG de Jesus-Ayson & O Reyes - Fish and Shellfish Immunology, 2010 - Academic Press
      Viral nervous necrosis (VNN) caused by betanodaviruses has been recently implicated in serious mortalities of groupers in the grow-out culture system. A safe and effective vaccine against this disease is urgently needed. This study demonstrates that a single intramuscular vaccination with formalin-inactivated Philippine strain of piscine betanodavirus (genotype: redspotted grouper nervous necrosis virus; RGNNV) induces potent immune responses and substantial protective immunity against an intramuscular challenge with the homologous virus in brown-marbled grouper, Epinephelus fuscogutattus, a highly susceptible marine fish species to VNN. Seroneutralization assay conducted on sera of vaccinated fish revealed the occurrence of substantial neutralizing-antibody titers from Days 15 (mean titer 1:800) to 190 (1:400) with the highest titer observed at Day 60 post-vaccination (1:5120). When vaccinated fish were challenged with the homologous virus at Days 15, 30 and 75 post-vaccination, significantly higher survival rates were obtained in these fish compared with their corresponding controls (L-15 injected fish). Abrogation of virus multiplication in all vaccinated survivors was indicated by undetectable virus titers in the brains and kidneys paralleled by significantly high levels of neutralizing antibodies in the sera of these fish. Consecutively, replicates of vaccinated fish that survived betanodavirus challenge at Days 15 and 75 post-vaccination were maintained in flow-through aquaria and rechallenged with the homologous virus 3 and 5 months later, respectively. A significant drop in neutralizing-antibody titers of 3 and 8 folds, respectively, were observed in the sera of Days 15 and 75 post-vaccinated fish assayed before the virus rechallenge. Interestingly, reversion in the levels of neutralizing antibodies to significantly high levels (8–15 folds) were noted in these fish after the virus rechallenge. Taken together, our current data clearly demonstrate that a single administration of the inactivated Philippine strain of betanodavirus vaccine can effectively mount a specific anamnestic response and concomitant long-term protection against VNN in grouper at the grow-out culture system.
    • Book chapter

      Reproductive biology of the Asian seabass, Lates calcarifer 

      EG de Jesus-Ayson & FG Ayson - In DR Jerry (Ed.), Biology and Culture of Asian Seabass Lates Calcarifer, 2014 - CRC Press
    • Article

      Susceptibility of hatchery-reared snubnose pompano Trachinotus blochii to natural betanodavirus infection and their immune responses to the inactivated causative virus 

      R Pakingking Jr., KI Mori, NB Bautista, EG de Jesus-Ayson & O Reyes - Aquaculture, 2011 - Elsevier
      Mass mortality of snubnose pompano Trachinotus blochii fry exhibiting dark coloration, anorexia, and abnormal swimming behavior was recently documented at the hatchery of the Aquaculture Department of the Southeast Asian Fisheries Development Center, Philippines. Samples of brain tissues were collected from affected fish and processed for RT-PCR amplification and virus isolation in cell culture. Infected E-11 cells exhibited cytopathic effect characteristic of betanodavirus. Histopathology of moribund fish showed pronounced vacuolations in the brain, spinal cord, and retina. An RT-PCR product of approximately 430 bp was amplified from the culture supernatant of betanodavirus-infected E-11 cells and sequenced. Sequencing of the T4 region of the coat protein gene (RNA 2) revealed clustering of the isolated virus within the red-spotted grouper nervous necrosis virus type. The pathogenicity of the isolated betanodavirus in healthy pompano juveniles and fry was determined via intramuscular injection and immersion challenges, respectively. Higher mortality rates were obtained in challenged fish compared with the controls. An inactivated vaccine was subsequently prepared by treating the clarified betanodavirus with formalin. Pompano juveniles intraperitoneally injected with the inactivated vaccine exhibited neutralizing antibodies from days 15 (mean titer 1:240) to 125 (1:560) with the highest titer noted at day 64 (1:2240) post-vaccination. Additionally, pompano fry bath-vaccinated and consequently bath-challenged with betanodavirus at day 35 post-vaccination showed higher survival rate compared with the control, indicating the potential of the inactivated betanodavirus vaccine against VNN in pompano fry and juveniles.
    • Book chapter

      Sustainable milkfish production in marine fish cages through strong government support and effective public-private partnerships: a case study from Panabo City Mariculture Park in Davao del Norte, Philippines 

      FG Ayson, AM Ventura & EG de Jesus-Ayson - In W Miao & KK Lal (Eds.), Sustainable intensification of aquaculture in the Asia-Pacific region. Documentation of successful practices, 2016 - FAO Regional Office for Asia and the Pacific
      This case study presents the successful practice of sustainable intensification of milkfish aquaculture in marine fish cages under semi-intensive grow-out conditions in the Panabo City Mariculture Park (PCMP) in Davao del Norte, Philippines. Established in 2006, PCMP became operational through the promulgation of a City Ordinance declaring 1 075 hectares of municipal waters in Panabo City as a Mariculture Development Zone/Park. The operations of PCMP were so successful that in just five years it became the third largest among the 63 operational MPs in the Philippines during 2011, with 86 private investors-locators operating a total of 322 units of cages. At present, a total of 372 units of fish cages are operating in the mariculture park (MP). A combination of factors contributed to the successful operation of PCMP, but the success is usually attributed to the effective partnership between the government (both local and national) and the private sector. The Comprehensive MP City Ordinance that governs the PCMP is strictly implemented and includes, among others, the tenurial rights and access to locators. Regulations on distances between cages are strictly enforced and security measures in the total area are jointly undertaken by the government and the locators. The national government, through the Bureau of Fisheries and Aquatic Resources-National Mariculture Center (BFAR-NMC), provides technical support in all aspects from stocking to harvest during the production cycle. BFAR-NMC staff conduct regular periodic sampling of the stocks and compute feeding rates for the stocks which are implemented by the technicians/caretakers. Likewise, BFAR-NMC staff regularly monitor the water quality of the MP and the health status of the stocks. Since it became operational in 2006, the PCMP did not report a single incident of mass fish kill, which indicates that the technical guidelines of MP operations are strictly followed. Workers are trained and organized into groups by BFAR-NMC such as caretakers, cage framers, netters, harvesters, fish processors, and others, and actively participate in discussions related to MP operations to ensure protocols are properly followed. Harvests of stocks are done by skilled workers trained by BFAR-NMC, all done in the “Bagsakan Center” or fish landing area and are well-coordinated. The support facilities in the fish landing area are provided by both the local and national government and the PCMP Producers Association. The operators provide complete data for their operations to BFAR-NMC for record keeping. The strong partnership between the national government through BFAR-NMC, the local government unit, the investors, as well as the acceptance and support from the community for the PCMP is the hallmark of its success.