Now showing items 1-18 of 18

    • Article

      Changes in mRNA expression of grouper (Epinephelus coioides) growth hormone and insulin-like growth factor I in response to nutritional status 

      FL Pedroso, EGT De Jesus-Ayson, HH Cortado, S Hyodo & FG Ayson - General and Comparative Endocrinology, 2006 - Elsevier
      Growth hormone (GH) and insulin-like growth factor-I (IGF-I) are key links to nutritional condition and growth regulation in teleost. To understand the endocrine mechanism of growth regulation in grouper, we cloned the cDNAs for grouper GH and IGF-I and examined their mRNA expression during different nutritional status. Grouper GH cDNA is 936 base pairs (bp) long excluding the poly-A tail. It contained untranslated regions of 85 and 231bp in the 5'- and 3'-ends, respectively. It has an open reading frame of 612bp coding for a signal peptide of 17 amino acids (aa) and a mature hormone of 187aa residues. Based on the aa sequence of the mature hormone, grouper GH shows higher sequence identity (>76%) to GHs of perciforms than to GHs of cyprinids and salmonids (53-69%). Grouper preproIGF-I cDNA consisted of 558bp, which codes for 186aa. This is composed of 44aa for the signal peptide, 68aa for the mature peptide comprising B, C, A, and D domains, and 74aa for the E domain. Mature grouper IGF-I shows very high sequence identity to IGF-I of teleost fishes (84-97%) compared to advanced groups of vertebrates such as chicken, pig, and human (=<80%). Using DNA primers specific for grouper GH and IGF-I, the changes in mRNA levels of pituitary GH and hepatic IGF-I in response to starvation and refeeding were examined by a semi-quantitative RT-PCR. Significant elevation of GH mRNA level was observed after 2 weeks of food deprivation, and increased further after 3 and 4 weeks of starvation. GH mRNA level in fed-controls did not change significantly during the same period. Hepatic IGF-I mRNA level decreased significantly starting after 1 week of starvation until the 4th week. There was no significant change in IGF-I mRNA levels in fed-controls. One week of refeeding can restore the GH and IGF-I mRNA back to its normal levels. Deprivation of food for 1-4 weeks also resulted in cessation of growth and decrease in condition factor.
    • Article

      Characterisation of Vibrio isolates recovered from the eyes of cage-cultured pompano (Trachinotus blochii) infested with caligid parasites (Lepeophtheirus spinifer) 

      R Pakingking Jr., NB Bautista, D Catedral & EG de Jesus-Ayson - European Association of Fish Pathologists Bulletin, 2018 - European Association of Fish Pathologists
      Exophthalmia was documented among sea cage-cultured pompano (Trachinotus blochii) broodstocks with caligid parasite (Lepeophtheirus spinifer) infestation in the Philippines. Following sequencing, and based on the results of both diagnostic investigations and infection experiments, V. harveyi likely had a role in the reported exophthalmia cases, and this was initiated by L. spinifer infection.
    • Article

      Cloning of mangrove red snapper (Lutjanus argentimaculatus) growth hormone cDNA and mRNA expression during early development 

      LP Samentar, FG Ayson, EGT de Jesus-Ayson & MJ Formacion - Philippine Journal of Natural Sciences, 2013 - University of the Philippines Visayas
      Growth hormone regulates growth and development in vertebrates. As a first step to understand the role of growth hormone in the regulation of growth and development of the mangrove red snapper Lutjanus argentimaculatus, the red snapper growth hormone (sGH) cDNA was cloned using reverse transcription - polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends. The expression of sGH mRNA in embryos and larvae was examined also by RT-PCR. Excluding the poly-A tail, the full-length red snapper GH cDNA is 945 base pairs (bp) long. It contains untranslated regions of 99 bp and 234 bp in the 5’ and 3’ ends, respectively. It has an open reading frame of 612 bp coding for a signal peptide of 17 amino acids and a mature hormone of 187 amino acid residues. Red snapper GH contains 4 cysteine residues and the typical polyadenylation site 16 bp upstream of the poly-A tail. Based on the amino acid sequence of the mature hormone, sGH shows higher sequence identity (>75%) to GHs of perciforms like grouper, seabass, tilapia and rabbitfish than to GHs of salmonids and carps. Semi-quantitative RT-PCR showed that expression of sGH mRNA commenced two days after hatching.
    • Book

      Development and management of milkfish broodstock 

      OS Reyes, EGT de Jesus-Ayson, BE Eullaran, VL Corre Jr. & FG Ayson - 2015 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 62
      The manual provides developed and refined techniques for collection and transport of spawned eggs and larvae, as well as larval rearing. It also describes the necessary facilities for maintaining milkfish broodstock.

      Guidelines on transporting broodstock, performing biopsy to determine sex of spawners, collecting and cleaning eggs, packing and transporting eggs to hatchery, incubating and hatching eggs, and packing and transporting of larvae are also provided in the manual.

      The importance of nutritional quality of the diet in relation to the performance of the milkfish broodstock and quality of resulting eggs and larvae is also explained in the manual.

      Broodstock feeds are enriched with vitamin C, beta-carotene, and other nutrients for better reproductive performance of broodstock and better egg and larval quality. It also offers formula to initially estimate the number of spawned eggs and determine the hatching rate.

      The manual guides stakeholders and operators who are interested in setting up breeding facilities for milkfish.
    • Article

      Effects of human chorionic gonadotropin (hCG) and handling stress on spermiation of silver perch Leiopotherapon plumbeus (Kner, 1864) 

      PJT Denusta, EGT de Jesus-Ayson, MA Laron & LMB Garcia - Journal of Applied Ichthyology, 2014 - Wiley
      This study determined the effect of human chorionic gonadotropin (hCG) and handling stress on the spermiation and milt response of silver perch Leiopotherapon plumbeus based on the measurement of spermatocrit, sperm density, and milt production. Compared to saline-injected fish, the mean spermatocrit (or packed sperm) of hCG-treated fish was significantly lower at 18 h (47.9%) and 30 h (40.2%) post-injection while mean sperm density was significantly lower at 30 h post-injection (3.6 × 106 cells μl−1) but not at 18 h. At 18 h (1.8 μl g-BW−1) and 30 h (2.5 μl g-BW−1) post-injection, mean milt production of hCG-treated fish was significantly higher than in the saline group. Milt consistency was also thinner in the hCG-treated group. Mean sperm density of handled fish (18.0 × 106 cells μl−1) was significantly lower than control fish (23.4 × 106 cells μl−1). However, mean sperm density of handled plus saline-injected (16.2 × 106 cells μl−1) and handled plus hCG-treated fish (8.4 × 106 cells μl−1) was significantly lower than in the control goup. Having thicker milt consistency, mean spermatocrit and milt production of handled (77.5%; 1.1 μl g-BW−1, respectively) and handled plus saline-injected fish (75.4%; 1.1 μl g-BW−1, respectively) were not significantly different from the control fish (76.2%; 1.3 μl g-BW−1, respectively). Handled plus hCG-treated fish had the lowest mean sperm density (8.4 × 106 cells μl−1) and spermatocrit (54.7%), but had the highest mean milt production (5.5 μl g-BW−1) among the treatment groups. These results demonstrate that the hCG injection effectively induces spermiation and milt expression and that handling-related stress negatively affects such responses. The spermatocrit method may be used to assess the spermiation and milt response of silver perch.
    • Article

      Environmental control of annual reproductive cycle and spawning rhythmicity of spinefoots 

      A Takemura, Y Takeuchi, T Ikegami, SP Hur, V Soliman, F Ayson, E de Jesus-Ayson & ES Susilo - Kuroshio Science, 2015 - Graduate School of Kuroshio Science, Kochi University
      Many teleost fishes inhabiting shallow tropical waters exhibit synchronous spawning around species-selective lunar phases during their spawning season. For example, ovaries of the goldlined spinefoot (Siganus guttatus) develop during a single period each year from June to July in the Ryukyu Islands, Japan, while those of the goldlined spinefoot in the Karimunjawa Archipelago, Indonesia, develop twice a year from March to May, and then again from September to November. Increases in photoperiod and water temperature are possible cues for the initiation of reproductive activity in the populations around the Ryukyu Islands, while the transition between the rainy and dry season may trigger the initiation of reproductive activity in the Karimunjawa Archipelago populations. Moreover, the goldlined spinefoot releases its gametes around the first quarter moon period of the lunar phase, and since the lunar phase is consistent within the Indo-Pacific Ocean, this species can likely perceive cues from the moon and transcribe them as internal signals. In fact, periodical changes in moonlight intensity are expressed as changes in the plasma levels of melatonin, an endogenous transmitter of environmental light/dark cycles. In addition, the mRNA expression levels of clock genes of neural tissues [Cryptochrome (Cry3) and Period (Per2)] change according to changes in the lunar cycle. To date, how the lunar cycle may affect endogenous reproductive processes in fish is not fully understood. However, knowledge of lunar spawning periodicity in commercially important species may help in the management of fisheries resources, determining where and when to prohibit fishing (e.g., time and area closures), as well as promoting efficient aquaculture techniques for inducing synchronous spawning.
    • Book

      Hatchery production of snubnose pompano Trachinotus blochii Lacepede 

      OS Reyes, EGT de Jesus-Ayson, FL Pedroso & MIC Cabanilla - 2014 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 56
      A 26-page extension manual describing the biology, broodstock acquisition & management, larval rearing, harvest & transport and prevention of diseases & parasites in hatchery production of pompano.
    • Book

      Health management of milkfish Chanos chanos 

      ER Cruz-Lacierda, EG Estante, EGT de Jesus-Ayson & VL Corre Jr. - 2015 - Aquaculture Department, Southeast Asian Fisheries Development Center
      This monograph provides updated information on diseases of marine and brackishwater cultured milkfish in the Philippines. The information presented here is largely based on the results of a three-year research project on milkfish at the University of the Philippines Visayas funded by the Department of Science and Technology (DOST). The project involved surveillance and monitoring of hatchery, nursery and grow-out operations for occurrence of diseases as well as on disease diagnosis, prevention and control. Previously documented reports in the Philippines and in other documents, both published and unpublished, are also included in this monograph. The diseases are discussed on a culture phase basis, that is, disease problems encountered in hatchery-reared larvae and fry are listed first, followed by diseases observed in fingerlings and juveniles grown in nursery and grow-out culture areas, and adult stages maintained in broodstock facilities. Information regarding the causative agent, diagnostic procedures, and methods of prevention and control for each disease are provided, if available.
    • Book

      Milkfish Chanos chanos cage culture operations 

      AG Gaitan, JD Toledo, MT Arnaiz, EGD Ayson, JP Altamirano, RF Agbayani, ND Salayo & CL Marte - 2014 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 58
      A 42-pages extension manual describing the biology, fingerling production, site selection, cage design and construction, measurement & analysis of water & sediment quality parameters and economic analysis.
    • Book chapter

      Milkfish hatchery and nursery production in the Philippines 

      EGT de Jesus-Ayson - In IC Liao & EM Leaño (Eds.), Milkfish aquaculture in Asia, 2010 - National Taiwan University; The Fisheries Society of Taiwan; Asian Fisheries Society; World Aquaculture Society
      Milkfish is the most important farmed fish species in the Philippines. In the last 5 years, milkfish production has been increasing. Culture of milkfish in brackishwater ponds still contributes most to milkfish production, although production from marine cages has been on the rise, recently. To sustain milkfish production, a reliable supply of good quality seeds is imperative. Following the spontaneous spawning of milkfish in floating net cages in 1979, protocols for broodstock management, breeding and seed production were developed and these have been continuously refined over the years. Compared to Indonesia and Taiwan, however, commercialization of milkfish seed production in the Philippines, took a long time to take off. Currently, there are a number of government-run and private milkfish hatcheries in operation. In contrast, milkfish fingerling production in brackishwater ponds has long been practiced in the Philippines and is an industry in itself. Traditionally, milkfish fry were from catch from the wild. Recently, more and more come from local hatcheries as well as fry imported from neighboring countries like Indonesia and Taiwan. Prospects for the milkfish hatchery and nursery industries are discussed in light of the Philippine government initiatives to increase fish production, including milkfish, through mariculture as well as by improving production efficiency in other traditional culture systems.
    • Book chapter

      Milkfish R&D in the Philippines 

      EGT de Jesus-Ayson - In IC Liao & EM Leaño (Eds.), Milkfish aquaculture in Asia, 2010 - National Taiwan University; The Fisheries Society of Taiwan; Asian Fisheries Society; World Aquaculture Society
      Culture of milkfish in brackish water ponds has been practiced for many years in the Philippines and recently its culture has expanded to fish cages in marine waters. Following the spontaneous spawning of milkfish in floating net cages in 1979, protocols for its seed production were developed. Studies to determine sustainable culture techniques in ponds and cages were conducted. Studies on nutritional requirements of milkfish at different developmental stages were done to reduce dependence on live prey organisms during hatchery operations and optimize feed formulations for nursery and grow-out cultures. In recent years, research geared towards the environmental impact of milkfish culture and ways to mitigate the negative effects of intensive farming practices. Prospects for the milkfish industry are discussed in light of the recent advances in milkfish R&D and Philippine government initiatives to increase fish production by mariculture.
    • Article

      Osmotic and chloride regulation in the hemolymph of the tiger prawn Penaeus monodon during molting in various salinities 

      RP Ferraris, FD Parado-Estepa, EG de Jesus & JM Ladja - Marine Biology, 1987 - Springer Verlag
      The effect of molting on osmotic and chloride concentrations in the blood of the prawn Penaeus monodon Fabricius (20±3 g) at various salinities was investigated. Prawns were obtained from ponds in Iloilo, Philippines, in 1984. They were stocked in salinities of 8, 20, 32 and 44‰, and their hemolymph was sampled during molt (Time 0), and then 0.125, 0.25, 0.5, 1, 2, 4, 6, 10 and 14 d after molting. Prawns during and immediately after molt tended to conform to the environmental osmolality. Subsequent postmolt (≧0.5 d) stages displayed more divergence from external salinity. The isosmotic point was higher (940±30 mOsm kg-1) during molt than during intermolt (663±8 mOsm/kg-1), suggesting different osmotic requirements in early molt. Hyperregulation of hemolymph chloride below 20‰ S, as well as isoionic point (301±6 mM), were independent of molting stage. At 20‰ S and above, newly molted (0 to 0.25 d post-molt) individuals tended to conform to the external chloride concentration while intermolt (≧0.5 d) post-molt individuals did not. Contribution of hemolymph chloride to hemolymph osmolality was greater during intermolt than during ecdysis, suggesting an important role for other negatively charged ions during molt. When molt occurred in 20‰ S (the test salinity most similar to the isoionic salinity), there was little or no change in hemolymph osmolality or chloride concentration from 0 to 14 d postmolt. At 8, 32 and 44‰ S, the change from molt to intermolt values in hemolymph osmotic and chloride concentrations was hyperbolic. Non-linear least-squares regression showed that prawns generally achieved intermolt values within 1 d after molting. Prawns at intermolt regulated hemolymph osmolality (620 to 820 mOsm kg-1) and chloride concentration (300 to 450 mM) at a much narrower range than during molt (520 to 1 170 mOsm kg-1 and 250 to 520 mM, respectively). Hemolymph osmolality was a more sensitive indicator of physiological response than hemolymph chloride concentration. Distribution and culture of P. monodon might be limited in low salinities by its ability to maintain a hemolymph osmolality ≧500 mOsm kg-1 during molt and ≧600 mOsm kg-1 in intermolt, and in high salinities by its capacity to reduce the hemolymph osmolality from values at molt to those in intermolt. Osmotic and chloride concentrations in the blood of P. monodon clearly varied with both molt stage and salinity of the medium. Dependence on external factors, however, gradually declined in older molt stages, suggesting a reduction in integument permeability and greater development of ion absorption/secretion mechanisms as the exoskeleton hardened.
    • Article

      Responses of intermolt Penaeus indicus to large fluctuations in environmental salinity 

      FD Parado-Estepa, RP Ferraris, JM Ladja & EG de Jesus - Aquaculture, 1987 - Elsevier
      The osmotic and chloride regulation by 5- to 10-g intermolt Penaeus indicus was investigated by abruptly changing medium salinity from seawater (32 ppt) to test salinities of 8, 20, 32 (control) or 40 ppt. Hemolymph samples were taken at 0, and then at 0.25, 0.5, 1, 2, 5 and 10 days after the change in salinity, and were analyzed for osmolality and chloride concentrations. Tissue water content was also determined. Throughout the study period, daily mortality was low (1.8%), and was the same among control and experimental salinities. Hemolymph osmolality and chloride as well as tissue water content were stable within 0.25 to 0.5 days after the abrupt salinity change, except for tissue water content at 8 ppt which did not reach a steady state for 2 days. Intermolt P. indicus exhibited hyperosmotic or hyperionic regulation in salinities below isosmotic or isoionic salinities, and hypoosmotic or hypoionic regulation in those above. Hemolymph osmolality and chloride were positive linear functions of external osmolality and chloride concentrations (slope=0.24±0.02 and 0.20±0.02, respectively). Isosmotic and isoionic values were 780 mOsm/kg and 330 mM, respectively. Percentage tissue water decreased as a function of external osmolality (−0.0056% kg mOsm−1) and hemolymph osmolality (−0.0232% kg mOsm−1), indicating that tissue cells were relatively permeable to hemolymph water, and that the hemolymph acted as a barrier to buffer the cells from large fluctuations in external salinity. These results indicate that, like many penaeids, P. indicus is a good osmoregulator suitable for culture in brackishwater ponds where there are large fluctuations in salinity.
    • magazineArticle

      Sandfish: Profitable cea cucumbers also supply bioremediation 

      MT Castaños, RV Ledesma, KG Corre & EG de Jesus-Ayson - Global Aquaculture Advocate, 2011 - Global Aquaculture Alliance
      Sandfish, a type of sea cucumber, are both a high-value culture species and one that supports the aquaculture of other fish species by cleaning up waste on the bottoms of ponds or sea cages. Hatchery and nursery technologies for sandfish are being continuously refined by Vietnam’s Research Institute of Aquaculture No. 3, the Southeast Asian Fisheries Development Center and their partners. These technologies have also been initially transferred to the private sector through a training course and manual.
    • Article

      Seasonal gonad cycle of the climbing perch Anabas testudineus (Teleostei: Anabantidae) in a tropical wetland 

      RAD Bernal, FA Aya, EGT de Jesus-Ayson & LMB Garcia - Ichthyological Research, 2015 - Springer Verlag
      Seasonal reproduction of the climbing perch Anabas testudineus in the Candaba wetland, Philippines, is described. Monthly specimens were collected, gonads and viscera excised, and the gonads histologically examined. Low mean female gonadosomatic index [GSI (%)] from September to February (0.3–2.1 %) increased in March (8.7 %), peaked in May (10.9 %), and declined in June (3.3 %), but increased again in July and August (8.3–5.5 %). Male GSIs (at least 1 %) were low from September until May, increased in June (2.5 %), and then declined thereafter. All the six oocyte and four spermatogenic cell development stages were observed in the gonads throughout the annual cycle. The ovary was dominated by primary growth oocytes (chromatin nucleolus, perinucleolus) from August to February (77–90 %), but yolky oocytes (previtellogenic, vitellogenic) comprised 15 % to 28 % of the ovary from March to July. Mature oocytes were present for most of the year, comprising 40 % of the total oocytes in March-April, peaking in May (50 %), but declining to 30 % in June–July. Spermatozoa consistently dominated the testis throughout the annual cycle, particularly in November and March (58 %). Food intake in both sexes was generally low during the dry season (December–April) when gonad activity was also low, but started to increase at the onset of the wet season (May–November) when gonad activity began to peak. These results demonstrate that the climbing perch gonads exhibit asynchronous development, allowing a protracted breeding season with intense gonad activity timed at the onset of the wet season, concurrent with increasing food intake through the rest of the season.
    • Book

      Seed production of milkfish Chanos chanos Forsskal 

      O Reyes, B Eullaran & EG Ayson - 2016 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 63
      A 26-page manual describing the site selection, hatchery design, spawning, larval rearing, natural food production, and economic analysis for milkfish.
    • Book

      Seed production of rabbitfish Siganus guttatus 

      FG Ayson, OS Reyes & EGT de Jesus-Ayson - 2014 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 59
      This manual is mainly intended to serve as a practical guide to fishfarmers and other stakeholders interested to venture in operating a rabbitfish hatchery. It details site selection, hatchery design & layout, and protocols in broodstock management, spawning, larval rearing, and harvest & transport. It has also a section on natural food production for rabbitfish larvae.
    • magazineArticle

      Supporting ASEAN good aquaculture practices: Preventing the spread of trans-boundary aquatic animal diseases 

      RV Pakingking Jr. & EG de Jesus-Ayson - Fish for the People, 2016 - SEAFDEC Secretariat
      The FAO Fishery Statistics had indicated that Asia is the top producer of fish and fishery products from both capture fisheries and aquaculture. Specifically, Southeast Asia had contributed 9-31% of the total aquaculture production in Asia from 1950 to 2014 with Indonesia and the Philippines accounting for the most at 23-63% and 10-45% of the total, respectively. Aquaculture has been viewed as a solution to the growing concern on food security issues as well as for the socio-economic stability of many countries in Southeast Asia. For such reason, aquaculture operations are being intensified to compensate for the declining production from capture fisheries and in order to nail the gap between supply and demand for fish and fishery products in the world. With intensification, aquaculture production has already overtaken the contribution of capture fisheries to the world’s total fisheries production. However, concerns on the safety and quality of aquaculture products have been raised as result of intensified fish farming operations. Added to such concern is the irresponsible introduction of aquatic species for aquaculture that serve as carriers of pathogens. As a result, a large number of infectious aquatic diseases have emerged threatening the sustainability of aquaculture in the Southeast Asian region. In an effort to address the emergence of transboundary diseases in the region, the Aquaculture Department of SEAFDEC (SEAFDEC/AQD) launched a program on Healthy and Wholesome Aquaculture which includes as one of its main objectives, the need to continue improving aquaculture production through innovations in fish health management.