Felix Ayson - Academia.edu (original) (raw)

Papers by Felix Ayson

Aquaculture Department, Southeast Asian Fisheries Development Center eBooks, 1998

AM Rights Reserved No part of this publication may be reproduced or transmitted in any form or by... more AM Rights Reserved No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without the permission in writing from the publisher.

Aquaculture, Nov 1, 2005

FIG. 1. Nucleotide sequences of the wild-type polyhedrin gene and transfer vectors surrounding th... more FIG. 1. Nucleotide sequences of the wild-type polyhedrin gene and transfer vectors surrounding the site of recombination and the initiation codons. The nucleotide sequences of the polyhedrin gene and of pAc373 are as described by Summers and Smith (32). The numbering system used is based upon the first transcribed nucleotide being designated 1.

General and Comparative Endocrinology, Apr 1, 2002

In rodents, the expression of insulin-like growth factor II (IGF-II) is higher than that of insul... more In rodents, the expression of insulin-like growth factor II (IGF-II) is higher than that of insulin-like growth factor I (IGF-I) during fetal life while the reverse is true after birth. We wanted to examine whether this is also true in fish and whether IGF-I and IGF-II are differentially regulated during different stages of embryogenesis and early larval development in rabbitfish. We first cloned the cDNAs of rabbitfish IGF-I and IGF-II from the liver. Rabbitfish IGF-I has an open reading frame of 558 bp that codes for a signal peptide of 44 amino acids (aa), a mature protein of 68 aa, and a single form of E domain of 74 aa. Rabbitfish IGF-II, on the other hand, has an open reading frame of 645 bp that codes for a signal peptide of 47 aa, a mature protein of 70 aa, and an E domain of 98 aa. On the amino acid level, rabbitfish IGF-I shares 68% similarity with IGF-II. We then examined the relative expression of the two IGFs in unfertilized eggs, during different stages of embryogenesis, and in early larval stages of rabbitfish by a semiquantitative reverse transcription-polymerase chain reaction. Primers that amplify the mature peptide region of both IGFs were used and PCR for both peptides was done simultaneously, with identical PCR conditions for both. The identity of the PCR products was confirmed by direct sequencing. Contrary to published reports for seabream and rainbow trout, IGF-I mRNA was not detected in rabbitfish unfertilized eggs; it was first expressed in larvae soon after hatching. IGF-II mRNA, however, was expressed in unfertilized eggs, albeit weakly, and was already strongly expressed during the cleavage stage. mRNAs for both peptides were strongly expressed in the larvae, although IGF-II mRNA expression was higher than IGF-I expression.

Southeast Asian Fisheries Development Center Three years after the Philippines became a signatory... more Southeast Asian Fisheries Development Center Three years after the Philippines became a signatory to the Agreement Establishing the Southeast Asian Fisheries Development Center (SEAFDEC) in January 1968, the Philippine Government submitted a Position Paper during the Fourth Meeting of the SEAFDEC Council in January 1971, formally inviting SEAFDEC to establish a regional aquaculture project in the Philippines. This was anchored on the decision reached during the Third Ministerial Conference for the Economic Development of Southeast Asia in 1968, for SEAFDEC to consider the establishment of a new department to deal with freshwater and brackishwater fish culture, in addition to the already established Research and Training Departments. Subsequently, the Ministerial Conference established a working group of aquaculture experts from the Member Countries to conduct a study on the aquaculture situation in Southeast Asia. Their report which indicated that the new SEAFDEC Department could be...

Growth hormone regulates growth and development in vertebrates. As a first step to understand the... more 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

Transactions of the National Academy of Science and Technology

The Philippines has long been recognized as a center of marine biodiversity, hence, rich in marin... more The Philippines has long been recognized as a center of marine biodiversity, hence, rich in marine resources. However, fisheries production has been declining in recent years. On the other hand, aquaculture now contributes about half of the total fisheries production. Notably, production from marine pens and cages (mostly milkfish) has increased dramatically in the last two decades. Mariculture areas are designed for production of marine fishes through sea cage culture, farming of seaweeds, mussels and oysters, sea ranching of abalone, aquasilviculture, and others that may be developed through continuing R&D programs. Much discussion has focused on how to achieve sustainability in aquaculture. Concerns are related to the expansion and intensification of aquaculture including its impact on the environment, outbreaks of diseases, sustainability of supply of seed, feed ingredients and feeding practices, and competition for coastal space.

The purpose of this project is to improve the growth and survival of the rabbitfish, Siganus gutt... more The purpose of this project is to improve the growth and survival of the rabbitfish, Siganus guttatus, cultured in Southeast Asia, by understanding the rate-limiting component(s) in the growthhormone-insuJin-like growth factor system, which inight explain the slow growth rate during the early juvenile stage and use this infonnation to enhance growth rate by administration ofgrowth hormone using various methodologies. During the period of the report, the growth hormone (GlI) from rabbitfish was purified and antiserum,wasraised in rabbits. This 'vvill enable the development of a quantitative assay. for the determination of circulating hormone levels. The native protein purified at the start of the project was used in growth enhancement experiments of rabbitfish kept under various salinities. The cDNAs for rabbitfish GH and inrulin"like growth factors I and n (IGF-I and IGF-II) were also cloned. Studies were initiatedto pmduce the GH protein in bacteria in large quantities in...

a Centre for Blue Governance, Faculty of Business and Law, University of Portsmouth, 6 Portsmouth... more a Centre for Blue Governance, Faculty of Business and Law, University of Portsmouth, 6 Portsmouth PO1 3DE, UK. 7 b Universidade Federal do Ceará Meireles, Fortaleza, Ceará, 60.165-081, Brazil 8 c Department of Fish Biology and Genetics, Bangladesh Agricultural University, 9 Mymensingh-2202, Bangladesh 10 d Department of Information, International Cooperation and Education, Dinh BangTu Son11 Bac Ninh, Vietnam 12 e Freshwater Fisheries Research Centre of Chinese Academy of Fishery Sciences, No. 9, East 13 Shanshui Rd, Wuxi, Jiangsu 214081, PR China 14 f SEAFDEC AQD, Tigbauan, Iloilo 5021, Philippines 15 g University of Zambia, Lusaka, Zambia 16 h Ministry of Fisheries Development, Kenya 17

Journal of Applied Ichthyology, 1990

Summary The effect of loading density, transport duration, water temperature, and salinity on sur... more Summary The effect of loading density, transport duration, water temperature, and salinity on survival of young rabbitfish (Siganus guttatus Bloch) under simulated transport conditions was investigated. The rocking motion of transport was simulated by an electric shaker. At ambient temperature and salinity (28°C/32 %˚ S) increasing loadin density and transport duration resulted in decreasin fish survival rates. When both temperature ant salinity (20°C/20%˚S) were lowered survival improved sinificantly. Dissolved oxygen, water temperature, and salinity were critical factors affecting survivaf of young rabbitfish during simulated transport. Based on the results, a density of 100 fish/L can be packed for 8 hours of transport and 300 fish/L for 2 hours at 28°C and 32 %˚, and about 200 fish/L for 4 hours at 20°C and 20%˚S. Zusammenfassung uberleben von jungen Siganus guttatus Bloch unter simulierten Tranrportbedingungen. Unter simulierten Transportbedinpngen wurde der Einflus der Besatzdichte, Transportdauer, Wassertemperatur und Salinitat auf die Uberlebensrate von juvenilen Siganus guttutus Bloch untersucht. Die bei dem Transport auftretenden Bewegungen wurden durch einen elektrischen Schuttler erzeugt. Bei Umgebunstemperaturen von 28°C und einer Salinitat von 32 %˚ wurden bei zunehmender Besatzdichte uni Transportdauer abnehmende uberlebensraten beobachtet. Bei verrninderter Temperatur und Salinitat des Transportmediums (20°C/20 %˚S) verbesserte sich die uberlebensrate sinifikant Geloster Sauerstoff, Wassertemperatur und Salinitat erwiesen sich als kritische Faktoren, die ias uberleben der Jungtiere von Siganus guttatus beeinflusten. Ausgehend von den Ergebnissen dieser Untersuchung konnen die Tiere bei 28°C und 32%˚S in einer Dichte von 100 Stuck/L fur 8 Stunden, bei einer Dichte von 300 Stuck/L fur 2 Stunden; sowie bei 20°C und 20%S bei einer Dichte von 200 Stuck/L fur 4 Stunden transportiert werden. Resume Survie de Siganus guttatus Bloch juveniles sous conditions de transport simulees L'effet de la densite de poissons, de la duree du transport, de la temperature de l'eau et de la salinite sur la survie de Siganus gutatus juveniles sous des conditions de transport simultes ont eteexaminees. Un vibrateur electrique a simule les secousses du transport A temperature et salinite ambiente (28°C, 32 %˚S), l'augmentation de la densite de poissons et de la duree de transport resultait en des taux de survie plus bas. Une diminuation de las temperature et de la salinite augmentait le faux de survie significativement. L'oxygene dissous, la temperature de l'eau et la saliniteetaient des facteurs importants qui avaient une influence sur la survie de Siganus guttatus juveniles pendant le transport simule. D'apres les resultats obtenus, une densite de 100 poissons par litre est possible pendant 8 heures de transport, 300 poissons par litre pendant 2 heures sa 28°C et 32%˚ de salinite, et environ 200 poissons par litre pendant 4 geures sa 20°C et 20%˚ de salinite.

This case study presents the successful practice of sustainable intensification of milkfish aquac... more 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

The manual provides developed and refined techniques for collection and transport of spawned eggs... more 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

Biotechnology, the science of manipulating genetic traits and substances, has been with us for ce... more Biotechnology, the science of manipulating genetic traits and substances, has been with us for centuries. The Chinese have created gold fish of different shapes, sizes and colors from a single species through centuries of breeding. New techniques in molecular biology, particularly genetic engineering, have made the field more exciting. Microorganisms act as the new drug factories. Harnessing them has made many medicines cheaper and more readily available. For example, insulin for diabetics is mostly produced by genetically altered bacteria through recombinant DNA technology. Biotechnological tools fueled the Green Revolution through the development of higher yielding varieties of rice, wheat and maize. Biotech is being held as the engine of the second Green Revolution one that would be less dependent on pesticides and fertilizers. The same tools have the potential to fuel another revolution, in another front a Blue Revolution. The rapid increase in population and the ensuing increas...

International Journal of Fisheries and Aquatic Studies, 2020

This paper has received funding from the EU 7th Framework Programme Project under grant agreement... more This paper has received funding from the EU 7th Framework Programme Project under grant agreement number 289760.

This study was supported in part by a Grant-in-Aid for Scientific Research (B) (JSPS KAKENHI Gran... more This study was supported in part by a Grant-in-Aid for Scientific Research (B) (JSPS KAKENHI Grant Numbers 15405029, 19405031, 22405029, and 25304032) from the Japan Society for the Promotion of Science (JSPS) to AT, by Joint Research project under the Japan-Korea Basic Scientific Cooperation Program from Japan Society for the Promotion of Science to AT, by Bicol University under the Siganid Recruitment Research Program to VS, and by Basic Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012R1AcA3A04041089) to SPH.

7 The world demand for river eels has been increasing mainly because of the market expansion of s... more 7 The world demand for river eels has been increasing mainly because of the market expansion of some delicacies such as the kabayaki (broiled eel with sweet soy sauce) in East Asia. While most of the world’s eel production is derived from aquaculture, it should be noted that eel aquaculture is still dependent on the natural resources. As techniques for the full-life cycle aquaculture of eels have not yet been fully developed for commercial use, the eel aquaculture industry is still solely dependent on wild resources for seed stocks. However, the natural resources had been confronted with various factors that could possibly create negative impacts on the eel resources including habitat alteration, overexploitation, climate change, pollution, and incidence of diseases. Thus, concerns on the sustainability of various eel species in the world have increased in recent years. It should be reckoned that the European and American eels are already threatened to certain degree by pollution an...

Marine Biotechnology, 2019

The availability of sexually mature fish often dictates the success of its captive breeding. In t... more The availability of sexually mature fish often dictates the success of its captive breeding. In this study, we induced reproductive development in juvenile protogynous tiger grouper through oral administration of a plasmid (p) containing an engineered folliclestimulating hormone (FSH). An expression construct (pcDNA3.1) was designed to express a single-chain FSH consisting of giant grouper FSH β-subunit and glycoprotein subunit-α (CGα), linked by the carboxy-terminal peptide (CTP) sequence from the human chorionic gonadotropin (hCG). Single oral delivery of pFSH encapsulated in liposome and chitosan to tiger grouper yielded a significant increase in plasma FSH protein level after 4 days. Weekly pFSH feeding of juvenile tiger groupers for 8 weeks stimulated ovarian development as indicated by a significant increase in oocyte diameter and progression of oocytes to cortical alveolar stage. As the pFSH treatment progressed from 20 to 38 weeks, female to male sex change was initiated, characterized by oocyte regression, proliferation of spermatogonial cells, and occurrence of spermatogenic cysts. It was also associated with significantly lower mRNA expression of steroidogenic genes (cyp11b, cyp19a1a, and foxl2) and basal plasma levels of sex steroid hormones 17β-estradiol (E 2), testosterone (T), and 11-ketotestosterone (11KT). Results suggest that pFSH stimulates ovarian development up to cortical alveolar stage and then initiates sex change in tiger grouper. These findings significantly contribute to our knowledge on the role of FSH in the development of protogynous hermaphroditic fish. This study is the first to demonstrate induction of reproductive development in fish through oral delivery of plasmid gonadotropin.

Aquaculture, 2019

The giant grouper is presumed to follow the reproductive pattern of most Epinephelus species, cha... more The giant grouper is presumed to follow the reproductive pattern of most Epinephelus species, characterized by protogynous hermaphroditism wherein male maturation is attained through sex reversal of a functional female. This hypothesis, however, has not been verified due to lack of biological data. The present study addresses this gap by investigating the reproductive development of giant groupers from juvenile stage through sexual maturity. Gonad histological analysis of hatchery-bred juvenile giant grouper from Queensland, Australia (0.8-5.2 kg, n=43) have shown earliest occurrence of primary oocytes (i.e. ovarian differentiation) in 47.8 cm and 2.5 kg fish. Monitoring of sexual maturity by gonadal biopsy was performed in a stock of wild-caught giant groupers (2-20 kg) held in sea cages in the Philippines and Vietnam from 2015 to 2017. Onset of female sexual maturity was at 96.9±1.6 cm and 23.5±1.5 kg in the Philippines, and 103.0±4.1 cm and 33.5±2.5 kg in Vietnam. In both locations, development of primary males was observed wherein fish produced milt (or spermiated) without passing through a functional female phase. The ratio of primary males to females in both locations was about 1:2. Size at maturity of primary males is 86.5±4.8 cm and 17.1±2.1 kg in the Philippines, and 97.3±1.3 cm and 34.3±0.9 kg in Vietnam. To aid in the monitoring of female maturation, we developed a non-invasive method based on immunoassay of vitellogenin in skin mucus and this was shown to be effective in detecting female maturation 9±2 months prior to first observation of oocytes through gonadal biopsy. Our findings suggest that giant grouper is a diandric protogynous hermaphrodite. This study provides novel information on the reproductive biology of giant grouper, an economically important and vulnerable species.