Genetic improvement of the Japanese eel (Anguilla japonica) can be achieved by artificially controlling its life cycle using recent advances in reproductive biology. In this study, we developed 43 microsatellite loci to confirm Mendelian inheritance at 10 of them as well at 16 previously reported in two full-sib families produced by artificial insemination. In order to establish a base for aquaculture genetics of this species in the near future, these microsatellite loci were mapped in relation to the centromere by half-tetrad analysis using four artificially induced triploid families. The second division segregation frequency (y) of the microsatellite loci ranged from 0.008 to 0.968 (mean ± SD = 0.645 ± 0.298). These results suggest the presence of strong chiasma interference in the eel. Significant differences were observed for the map distances of microsatellite loci between the two isolation procedures. Microsatellites isolated using the enrichment procedure were mapped to various sites starting from the centromere to the telomere, whereas those from the conventional size-selected library showed a tendency to be distributed in the telomeric region.

Gracilaria heteroclada Zhang et Xia was grown in filter tanks to determine the growth, agar quality and uptake pattern of nitrogen and to observe the water quality in recirculating water system with seaweed. Rapid uptake of nitrogen in G. heteroclada was observed within the first 24th of culture. Filling up of the nitrogen pools in the cell may have continued until the fifth day, the plants started to increase in weight, proportionate to the uptake rate of nitrogen duing the experiment. G. heteroclada stocked at 1 kg m^-2achieved a specific growth rate (SGR) of approximately 10.4% d^-1 during 15d of culture, at total ammonia-nitrogen and nitrite-nitrogen levels of 0.03-0.27 mg L^-1 and 0.04-0.19mg L^-1, respectively, in the filter tank. Approximately 11% of nitrogen in the water was removed by the seaweed.

A probable vertical mode of piscine nodavirus transmission is reported in the present investigation based on a case of nodavirus associated larval mortalities in hatchery produced Asian sea bass. Polyclonal rabbit anti-SJNNV antibodies (SGWak97) detected the viral antigens in the tissue sections from the eggs and the larvae at different time intervals from − 1 to 42 days post hatch (dph). Immunopositive ovarian connective tissue associated with the oocytes along with the progressive localization of the viral antigens in the brain, spinal cord, liver, stomach and dermal musculature during the larval development indicates a probable vertical transmission of nodavirus in the Asian sea bass. The surviving larger larvae, from the batch suffering mass mortalities, produced very intense immunofluorescent positivity in the liver, stomach and dermal musculature. Results of this investigation demonstrating a possibility of vertical transmission of the nodavirus emphasize the need for screening of eggs and larvae for evolving suitable preventive and prophylactic health management strategies.

The lipid content and fatty acid composition were examined in the liver, eye, muscle, brain and intraperitoneal fat body (IPF) of hatchery-bred and wild-caught orange-spotted grouper, Epinephelus coioides. The cultured and wild grouper were classified into three different body weights (small, medium and large size), and submitted to lipid content and fatty acid analysis. Muscle lipid in cultured grouper increased lineally with growth, but that of wild fish decreased. The amount of lipid in the IPF in cultured fish was higher than wild fish. Lipid content and essential fatty acids in cultured fish showed significant change with growth. All organs in the early growth stage of cultured fish seemed to contain poor arachidonic acid (AA) than the wild fish. The liver of small sized cultured fish contained low AA and docosahexaenoic acid (DHA), but no profound change was found in AA during growth of fish. While the proportion of DHA in the liver and IPF increased with growth in cultured fish, muscle DHA decreased with growth. The difference in fatty acid composition between cultured and wild fish disappeared with growth.

Vertebrate reproduction is under the neuroendocrine control of the hypothalamic decapeptide GnRH which synchronizes various reproductive events and influences other reproduction related aspects like spawning behavior and pheromonal action in fish. Multiple forms of GnRH peptides have been reported across diverse vertebrate and invertebrate classes. Here we report the partial seabream GnRH (sbGnRH) cDNA sequence cloned from the brain of Channa striatus (snake head murrel) a fresh water perciform with immense economic and medicinal value across Asiatic countries. sbGnRH mRNA was found in brain, gill and ovary of mature murrel with possible implications to the effect of GnRH on pheromonal phenomena and on reinitiation of oocyte meiosis. In keeping with the earlier reported role of GnRH in initiation of oocyte meiosis we here present evidence from RT-PCR, ICC demonstrating an increase in the level of sbGnRH mRNA in ovary from pre-vitellogenic to post-vitellogenic follicles.

The Southeast Asian Fisheries Development Center (SEAFDEC) is a regional treaty organization with 11 member countries. This was established in 1967 to promote fisheries development in Southeast Asia. As one of four SEAFDEC departments, the Aquaculture Department based in Tigbauan, Iloilo, Philippines, has conducted activities for aquaculture research and development in the region. Since 2000, the Regional Fish Disease Project has been implemented at the SEAFDEC Aquaculture Department through the Government of Japan Trust Fund. Under this project, research studies were conducted on various aspects of viral, bacterial and parasitic diseases of fishes and shrimps. In East Asia, koi herpesvirus (KHV) disease initially occurred in Indonesia and Taiwan in 2002. KHV infection was also found in Japan in 2003. This disease had a serious, devastating impact on common carp and koi (Cyprinus carpio) production in Indonesia and common carp production in Japan. Common carp is an important food resource in the rural areas of the region, while koi is internationally traded as ornamental fish among Southeast Asian countries. Under these situations, the Regional Fish Disease Project identified KHV as a serious, transboundary pathogen in the region and decided to work on KHV disease at the SEAFDEC Aquaculture Department in coordination with the SEAFDEC member countries to prevent the spread of KHV in the region. The planned research includes survey of the distribution of KHV in the region, standardization of the PCR (polymerase chain reaction) detection method, characterization of the virus isolated from the region, mode of transmission of KHV, and pathophysiology of KHV-infected fish. To support establishment of the fish disease quarantine and surveillance in Southeast Asia, the Regional Fish Disease Project has, since 2002, annually conducted a hands-on training at the SEAFDEC Aquaculture Department on viral diseases of fishes and shrimps for scientists and technical staff from the SEAFDEC member countries. The trainees are expected to play key roles in the diagnosis, prompt information exchange, and surveillance of fish diseases, including KHV disease, in their respective countries. The Regional Fish Disease Project organized two meetings in March 2004 and will convene another meeting in June 2004: Pre-KHVD Symposium Meeting, International Symposium on Koi Herpesvirus Disease, and Meeting on Current Status of Transboundary Fish Diseases in Southeast Asia: Occurrence, Surveillance, Research and Training.

The read seaweed Kappaphycus alvarezii (Doty) Doty ex. P.C. Silva, commonly called "cottonii" in the processing industry, is used as raw material for the production of the hydrocolloid kappa carrageenan. Through biotechnological advaces, certain carrageenan-producing seaweeds have been truly "domesticated" and are now successfully farmed as marine crops in a number of suitable areas of the world. Significant and sustainable employment opportunities are generated by these activities with few environmental impacts. In mid-2001, the incidence of very heavy epiphytism of cultivated raw material of K. alvarezii (cottonii) was reported for a production centre in the Philippines. This case of epiphytism was "unusual" in that it had been present for a considerable period of time and following epiphyte growth, the seaweed crop began to rot and fall off the cultivation lines (this was not the case of the disease "ice-ice"). The outbreak of the epiphyte infestation followed successional development of an epiphyte community and resulted in a climax population of the read seaweed Polysiphonia sp. This was observed to be preceded by heavy precipitation with consequent siltation reaching the farm site. The presence of the Polysiphonia sp. gave the plants a "hairy" appearance. Where the Polysiphonia was attached, the host plant seemed to produce "galls". The end result was that the Kappaphycus material rotted, fragmented and fell off the cultivation lines. The impact of this epiphyte attack was economically, socially and ecologically serious in that the farmers became disillusioned and either moved from the islands to other cultivation sites, leaving their families behind, or returned to the environmentally damaging practices of dynamite and or cyanide reef fishing. This paper outlines the events of epiphytic settlement and subsequent decomposition of the crop plants. The impact of Kappaphycus farming in the north-east Philippines is outlined as well as steps undertaken to improve the farming practice and enable farmers to return to the sustainable activity of seaweed farming.

Four species of sea lice were found parasitic on ten species of marine fishes either cultured in the coastal ponds or occurring in the sea water supply canals in the Philippines. They are: Caligus epidemicus Hewitt, 1971 on Acanthurus mata Cuvier), Epinephelus coioides (Hamilton), Glossogobius celebius (Valenciennes), Liza parmata (Cantor), Lutjanus argentimaculatus (Forsskael), Monodactylus argenteus (Linnaeus), Oreochromis urolepis hornorum (Trewavas), Oreochromis mossambicus (Peters), Rachycentron canadum (Linnaeus), and Siganus guttatus (Bloch); Caligus quadratus Shiino, 1954 on L. argentimaculatus and S. guttatus; Lepeophtheirus sigani n. sp. on S. guttatus; and Pseudocaligus uniartus n. sp. on S. guttatus and L. argentimaculatus. These ten species of fishes are new host to C. epidemicus, except for O. mossambicu which has been reported to carry C. epidemicus from Taiwan. Caligus quadratus is new to the Philippines and the two species of fish harboring it are the new host. While L. sigani was found only on S. guttatus, P. uniartus was recovered mostly from S. guttatus, and C. quadratus, largely from L. argentimaculatus. Caligus epidemicus exhibits extremely low host specificity and was found on all species of fishes examined.

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.

A local algal isolate Tetraselmis tetrathele was studied to determine the suitable levels of three growth factors (nutrient medium, light intensity and photoperiod) for mass culture. Significantly higher population cell count (141.92 × 10⁴) were found in 4-day-old cultures (exponential phase) enriched with Conwy medium and exposed continuously to 93.31–103.5 μmole photon m⁻² s⁻¹ light intensity compared with two other media (F, SEAFDEC/AQD) under the same light conditions. Cultures exposed to higher levels of photosynthetic photon flux density and continuous photoperiod had a significantly higher cell count regardless of nutrient media used. The chemical composition of T. tetrathele varied as the culture aged. Significantly higher crude protein (49.6%) and crude ash (15.9%) were found in cultures harvested at exponential than at stationary phase of growth. In contrast, significantly higher carbohydrate (55.2%) was noted as the culture aged. There was an increase in the percentage of saturated, monoenoic and n-3 highly unsaturated fatty acids at the stationary phase of growth. Addition of filtrate from various phases of growth and from 10-day-old cultures at various concentrations stimulated cell growth of T. tetrathele. This study identified the optimum growth conditions for mass culture of T. tetrathele and demonstrated its change in the chemical composition as the culture aged.