Now showing items 1-4 of 4

    • 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

      Dietary administration of dehydroepiandrosterone hormone influences sex differentiation of hybrid red tilapia (O. niloticus x O. mossambicus) larvae 

      AH Mohamed, RFM Traifalgar, AE Serrano Jr., JP Peralta & FL Pedroso - Journal of Fisheries and Aquatic Science, 2012 - Academic Journals, New York
      Effects of a steroid hormone Dehydroepiandrosterone (DHEA) on sex differentiation of hybrid red Tilapia Oreochromis niloticus x O. mossambicus larvae were investigated. Three day-old tilapia larvae were fed diets supplemented with varying concentrations of DHEA (0, 20, 40, 80 and 160 mg kg-1 feed) for 24 days. A positive control group fed with diet containing 60 mg kg-1 of 17α-methyl testosterone was also included in the experimental run. Results indicate that among the DHEA treatment groups, larvae fed with 160 mg kg-1 DHEA showed the highest percentage of males that is comparable to the number of differentiated male fish observed in treatment group receiving the 17α-methyl testosterone as the positive control group. DHEA supplementation also improves weight gain and enhances feed conversion ratio. These findings suggest that DHEA can be used as a dietary supplement to induce masculinization and can improve the growth performance of tilapia larvae.
    • Article

      Effects of elevated temperature on the different life stages of tropical mollusk, donkey's ear abalone (Haliotis asinina) 

      FL Pedroso - Aquaculture, Aquarium, Conservation and Legislation, 2017 - Bioflux
      The increase in sea surface temperature associated with climate change can cause tremendous impact on the different life stages of aquatic organisms, particularly on the tropical species. The present study investigates the effect of elevated temperature on hatching rate, growth and survival of larvae and breeders of tropical mollusk, donkey’s ear abalone (Haliotis asinina). Different life stages of abalone were exposed to the following temperature treatments: ambient (29°C), +2°C (31°C), and +4°C (33°C). Hatching rate was significantly reduced when the fertilized eggs were incubated at temperature 4°C above ambient. Increase in temperature at 2°C above ambient can significantly influence the survival of larvae. Significant decline in the survival was observed when the larvae were exposed at temperatures 31°C and 33°C, however bigger larvae were observed in groups reared at 31°C, while those larvae that were reared in 33°C were significantly smaller. Furthermore, reduced growth, feeding rate and survival were also observed in breeders reared at elevated temperature. The result of the study suggests that early developmental stages and reproducing adult abalone were vulnerable to the impact of climate change.
    • 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.