Now showing items 1-13 of 13

    • Article

      Differential expression of insulin-like growth factor I and II mRNAs during embryogenesis and early larval development in rabbitfish, Siganus guttatus 

      FG Ayson, EGT de Jesus, S Moriyama, S Hyodo, B Funkenstein, A Gertler & H Kawauchi - General and Comparative Endocrinology, 2002 - Academic Press
      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.
    • magazineArticle

      Ecological impacts of coastal aquaculture developments 

      Southeast Asian Fisheries Development Center, Aquaculture Department - Aqua Farm News, 1995 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The study presents the type and scale of any ecological change associated with coastal aquaculture development. These are enrichment, interaction with the food web, oxygen consumption, disturbance of wildlife and habitat destruction, interaction between escaped farmed stock and wild species, introduction and transfers, bioactive compounds (including pesticides and antibiotics), chemicals introduced via construction materials, and hormones and growth promoters.
    • Article

      Effect of growth hormone and γ-aminobutyric acid on Brachionus plicatilis (Rotifera) reproduction at low food or high ammonia levels 

      WG Gallardo, A Hagiwara, Y Tomita & TW Snell - Journal of Experimental Marine Biology and Ecology, 1999 - Elsevier
      Growth hormone (GH, 0.0025 and 0.025 I.U. ml−1) and γ-aminobutyric acid (GABA, 50 μg ml−1) enhance rotifer population growth in batch cultures. In order to further understand the mechanism of their actions, we conducted experiments culturing isolated females at low food and high free ammonia levels. At an optimum food level of 7×106Nannochloropsis oculata cells ml−1 or at low free ammonia level of 2.4 μg ml−1, the F1 offspring of rotifers treated with GH at 0.0025 I.U. ml−1 had significantly higher population growth rate (r) and net reproduction rate (Ro), and shorter generation time than untreated rotifers. At a lower food level of 7×105 cells ml−1 or at high free ammonia level of 3.1 μg ml−1, rotifers treated with GABA at 50 μg ml−1 had significantly higher r and Ro, and shorter generation time. These results indicate that GABA is effective in enhancing rotifer reproduction when rotifers are cultured under stress whereas GH enhances rotifer reproduction when culture conditions are optimal. Significant effects were also observed in F1 and F2 generations which were not treated with hormones. These data may be useful for treating rotifer mass cultures to mitigate the effects of stress caused by high population densities.
    • Article

      Effects of physico-chemical factors and nutrients on the growth of Spirulina platensis isolated from Lake Kojima, Japan 

      SF Baldia, T Nishijima & Y Hata - Nippon Suisan Gakkai Shi. Bulletin Of The Japanese Society Of Scientific Fisheries, 1991 - The Japanese Society of Fisheries Science
      The effects of physico-chemical factors and nutrients on the growth responses of Spirulina platensis isolated from Lake Kojima (K-2 strain) were determined. The optimum conditions for growth were the following: ligh intensity of 2,500-10,000 lx, pH 6.5-9.0, 30 to 35°C temperature and 0-7.6‰ of chlorinity. S. platensis (K-2 strain) requires no vitamins for growth essentially. However, growth enhancement was observed with vitamin B12 among the B-group witamins tested. Likewise, hormones such as kinetin and giberellin exhibited stumulatory effect on growth. The alga could utilize inorganic and organic phosphorus sources. Values on the different growth parameters for orthophosphate, β-glycerophosphate, adenosine diphosphate, and phos phocreatine were comparatively similar; half-saturation constant, maximum growth rate, minimum cell quota and level for saturated growth yield were about 0.01-0.02 mg P/ℓ, 0.8/day, 0.1-0.2 pg P/cell, and 0.4-0.7 mg P/ℓ, respectively.
    • Article | Review

      Growth regulation by insulin-like growth factor-I in fish 

      S Moriyama, FG Ayson & H Kawauchi - Bioscience, Biotechnology and Biochemistry, 2000 - Japan Society for Bioscience, Biotechnology, and Agrochemistry
      Insulin-like growth factor-I (IGF-I) is a mitogenic polypeptide that plays an essential role in the regulation of development and somatic growth of vertebrates, mainly by mediating growth hormone actions. It has clearly been established that the structure of IGF-I and its biological function has been highly conserved among vertebrates. In this paper, we review the recent developments in the molecular, biochemical, and physiological properties of IGF-I in fish.
    • Article

      Growth, survival and feed conversion of Nile tilapia fingerlings fed diets containing Bayo-n-ox, a commercial growth promoter 

      CB Santiago - The Israeli Journal of Aquaculture-Bamidgeh, 1991 - Society of Israeli Aquaculture and Marine Biotechnology
      A feeding experiment was conducted to determine the effect of a commercial growth promoter, Bayo-n-ox, on Nile tilapia fingerlings (mean initial weight 3.6 g). After 6 weeks, the weight gain of fish given 25 mg Bayo-n-ox/kg body weight was somewhat higher than that of the control fish. A slight growth depression was manifested by fish given 50 mg Bayo-n-ox/kg body weight. Total length followed a trend similar to that of weight gain. However, growth, the feed conversion ratio and the survival rate were not significantly different (p > 0.05) among treatments.
    • Article

      Isolation, cDNA cloning, and growth promoting activity of rabbitfish (Siganus guttatus) growth hormone 

      FG Ayson, EGT de Jesus, Y Amemiya, S Moriyama, T Hirano & H Kawauchi - General and Comparative Endocrinology, 2000 - Elsevier
      We report the isolation, cDNA cloning, and growth promoting activity of rabbitfish (Siganus guttatus; Teleostei; Perciformes; Siganidae) growth hormone (GH). Rabbitfish GH was extracted from pituitary glands under alkaline conditions, fractionated by gel filtration chromatography on Sephadex G-100, and purified by high-performance liquid chromatography. The fractions containing GH were identified by immunoblotting with bonito GH antiserum. Under nonreducing conditions, the molecular weight of rabbitfish GH is about 19 kDa as estimated by SDS–PAGE. The purified hormone was potent in promoting growth in rabbitfish fry. Weekly intraperitoneal injections of the hormone significantly accelerated growth. This was evident 3 weeks after the start of the treatment, and its effect was still significant 2 weeks after the treatment was terminated. Rabbitfish GH cDNA was cloned to determine its nucleotide sequence. Excluding the poly (A) tail, rabbitfish GH cDNA is 860 base pairs (bp) long. It contained untranslated regions of 94 and 175 bp in the 5′ and 3′ ends, respectively. It has an open reading frame of 588 bp coding for a signal peptide of 18 amino acids and a mature protein of 178 amino acid residues. Rabbitfish GH has 4 cysteine residues. On the amino acid level, rabbitfish GH shows high identity (71–74%) with GHs of other perciforms, such as tuna, sea bass, yellow tail, bonito, and tilapia, and less (47–49%) identity with salmonid and carp GHs.
    • Article

      Milkfish (Chanos chanos) growth hormone cDNA cloning and mRNA expression in embryos and early larval stages. 

      EGT de Jesus, FG Ayson, Y Amemiya, S Moriyama, S Hyodo, T Hirano & H Kawauchi - Aquaculture, 2002 - Elsevier
      In an attempt to understand growth regulation in milkfish, the milkfish growth hormone (GH) and its cDNA were characterized and the expression of GH mRNA in embryos and larvae was examined by RT-PCR. The milkfish GH was purified from an alkaline extract of the pituitary by reverse-phase high-performance liquid chromatography and detected as an immuno-positive protein with anti-salmon GH serum. The complete sequence of milkfish pre-GH was determined by cDNA cloning and nucleotide sequencing. On the basis of the N-terminal amino acid analysis of the native protein, the pre-GH was found to consist of a signal peptide of 22 amino acids and a mature protein of 188 amino acids. Milkfish GH shows higher amino acid sequence identity with GHs of carps (91–94%) and salmonids (70%) than with GHs of more advanced teleosts (<60%) in good accordance with its taxonomic position in teleosts. It has five half Cys residues, four of which are at positions homologous with those of other known GHs and the extra Cys with those of carp GHs. The molecular weight of milkfish GH was estimated to be 22 kDa, which is comparable to the theoretical value. This suggests that milkfish GH is a simple protein, although it has two potential N-glycosylation sites. Semiquantitative RT-PCR showed that GH mRNA expression was relatively weak in embryos and newly hatched larvae but was already strong in 2-day old and older larvae.
    • Article

      Responses of a non-migratory stock of brown trout, Salmo trutta, to ovine growth hormone treatment and seawater exposure 

      JME Almendras, P Prunet & G Boeuf - Aquaculture, 1993 - Elsevier
      The ability of ovine growth hormone (oGH) to enhance the hypo-osmoregulatory performance of a non-migratory stock of the brown trout (Salmo trutta) was investigated. Three groups of juvenile fish were intraperitoneally implanted either with a cholesterol pellet (sham) or with a cholesterol pellet containing 250 μg oGH (treated); control fish did not receive any implant. While still in fresh water, the gill Na+⁄K+-ATPase activity of the oGH-treated group was four times higher than that of sham and control groups 2 weeks after implantation. Transfer to sea water (SW) resulted in marked increases in plasma electrolyte levels of the sham and control groups, whereas the oGH-treated group showed only minor perturbations in plasma electrolyte concentrations. Subsequent regulation of plasma electrolyte parameters to lower levels was slower or less effective in the non-treated groups than in the oGH-treated group. In the non-treated groups, SW exposure brought about significant increases in gill Na+⁄K+-ATPase activity but only after a time lag of 7 days. An additional significant increase in gill Na+⁄K+-ATPase activity was also observed in the oGH group 7 days after SW exposure. By the end of the experiment, oGH-treated fish were significantly larger than non-treated ones. The data indicate that after oGH administration, juvenile non-smoltifying brown trout respond to SW exposure in the same manner as a fully smolted salmonid.
    • Article

      Semi-mass culture of the dinoflagellate Gymnodinium splendens as a live food source for the initial feeding of marine finfish larvae 

      EM Rodriguez & K Hirayama - Hydrobiologia, 1997 - Springer Verlag
      A technique was developed for the semi-mass culture of the unarmored dinoflagellate, Gymnodinium splendens under laboratory conditions. A maximum cell density of 4600 to 6800 cells ml−1 was observed within 8 to 11 days of culture. An initial feeding test for 8 days with three important marine finfish larvae showed that red spotted grouper, Epinephelus akaara preferred G. splendens fed 200 cells ml−1 with 44% survival. The Japanese stripe knife jaw, Oplegnathus fasciatus, attained 22% survival fed a combination of G. splendens and rotifers (200 cells ml−1 and 5 ind. ml−1, respectively). Red sea bream, Pagrus major larvae did not respond well to the initial feeding of G. splendens alone. Red sea bream were observed to be solely dependent on rotifers (5 ind. ml−1) as initial food. Gymnodinium splendens may be used as a live food in the initial feeding of red spotted grouper larvae (E. akaara) to reduce mortality and to further enhance growth during the critical first few days of rearing.
    • Article

      Thyroid hormone surges during milkfish metamorphosis. 

      EG de Jesus - The Israeli Journal of Aquaculture-Bamidgeh, 1994 - Society of Israeli Aquaculture and Marine Biotechnology
      Both thyroxine (T4) and triiodothyronine (T3) were detected in fertilized eggs and larvae of milkfish. The concentration of T4 was lower than that of T3 only in fertilized eggs and newly-hatched larvae. The total body concentrations of both thyroid hormones decreased after hatching. The T4 concentration fluctuated at relatively low levels during the first week after hatching, increased gradually during the next 2 weeks and was highest in 4-week-old larvae. On the other hand, T3 was undetectable in samples taken between days 3 and 11, showed a gradual increase beginning on day 13 and was highest in 27 day old larvae. The concentrations of both T4 and T3 declined again in 31-day-old juveniles. The peak corresponds with the development of silver coloration in hatchery-reared milkfish and the inshore milkfish and the inshore migration of larvae in the wild, suggesting a role for thyroid hormones during early development of this species.
    • Article

      Thyroid hormones promote early metamorphosis in grouper (Epinephelus coioides) larvae 

      EGT de Jesus, JD Toledo & MS Simpas - General and Comparative Endocrinology, 1998 - Academic Press
      The response of grouper larvae to the thyroid hormones, thyroxine (T4) and triiodothyronine (T3), was examined. Two-, 3-, and 4-week-old grouper larvae were reared in seawater containing either T4 or T3 at 0.01, 0.1, and 1 ppm. T4 or T3 induced metamorphosis in all age groups in a dose-dependent manner. Regardless of the size of the larvae, metamorphosis was completed in 2 days in larvae treated with 1 ppm of either T4 or T3; 3–4 days in larvae exposed to 0.1 ppm; and 5–6 days in larvae immersed in 0.01 ppm. None of the fish in the control group completed metamorphosis during this period. Compared with the control fish, survival rates were higher in groups exposed to 0.01 ppm and lower in those exposed to 1 ppm of T3. In 4-week-old larvae, T4 treatment (0.01 to 1.0 ppm) resulted in higher survival compared to the control. These results suggest that a dose of 0.01 ppm is appropriate for acceleration of metamorphosis and improvement of survival in 3- and 4-week-old grouper larvae. A lower dose may be apropriate for earlier stages.
    • Article

      Use of Acadian marine plant extract powder from Ascophyllum nodosum in tissue culture of Kappaphycus varieties 

      AQ Hurtado, DA Yunque, K Tibubos & AT Critchley - Journal of Applied Phycology, 2009 - Springer Verlag
      Three varieties of Kappaphycus alvarezii (Kapilaran, KAP), Tambalang purple (PUR), Adik-adik (AA), and one variety of Kappaphycus striatum var. sacol (green sacol (GS) were used to determine the efficiency of Acadian marine plant extract powder (AMPEP) as a culture medium at different concentrations, for the regeneration of young plants of Kappaphycus varieties, using tissue culture techniques for the production of seed stock for nursery and outplanting purposes for the commercial cultivation of carrageenophytes. A shorter duration for shoot formation was observed when the explant was treated with AMPEP + Plant Growth Regulator (PGR = PAA + zeatin at 1 mg L−1) compared to AMPEP when used singly. However, four explants responded differently to the number of days required for shoot formation. The KAP variety took 46 days to form shoots at 3–4 mg L−1 AMPEP + PGR; while PUR required 21 days at 3–5 mg L−1 AMPEP and 3–4 mg L−1 AMPEP + PGR. AA required 17 days at 3–5 mg L−1 AMPEP and AMPEP + PGR; and GS 25 days at 1 mg L−1 AMPEP + PGR. It was observed that among the four explants used, PUR and AA initiated shoot formation with the use of AMPEP only at higher concentrations (3–5 mg L−1) after a shorter period. Only PUR responded positively to ESS/2 for shoot initiation. The use of AMPEP alone and/or in combination with PGR as a culture medium in the propagation of microplantlets using tissue culture technique is highly encouraging.