Browsing by Author "de la Peña, Milagros R."
BookAC Fermin, MR de la Peña, RSJ Gapasin, MB Teruel, SMB Ursua, VC Encena II & NC Bayona - 2008 - Aquaculture Department, Southeast Asian Fisheries Development Center
Series: Aquaculture extension manual; No. 39This manual contains information on abalone hatchery operation, including site selection, design, culture of natural food, broodstock management, spawning, nursery, packing and transport, and profitability analyses.
ArticleEB Seraspe, BF Ticar, MJ Formacion, IG Pahila, MR de la Peña & EC Amar -
Asian Fisheries Science, 2012 - Asian Fisheries SocietyThe antibacterial properties of the microalgae Chaetoceros calcitrans were assessed. Samples of C. calcitrans were first extracted in methanol, and then in different organic solvents of increasing polarity, n-hexane (n-Hex), dichloromethane (DCM) and ethyl acetate (EA) by liquid-liquid extraction. Solvent extracts were screened for antibacterial activity against four species of bacteria: Gram positive, Staphylococcus aureus and Bacillus subtilis; and Gram negative, Escherichia coli and Vibrio harveyi, with Amoxicillin as positive control, N-Hex extract, with significantly lower antibacterial activity than Amoxicillin, showed significantly higher activity than DCM and EA extracts, and least in methanolic extract. High antibacterial activity of n-Hex extract against all the microorganisms indicates that the bioactive components could be non-polar since the activity decreased as the solvent became more polar like methanol, and finally lost in aqueous extract. Results also showed that the extracts have a broad spectrum activity. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of all solvent extracts on all microorganisms tested ranged from 125 to 500 μg.mL-1. Partial purification and characterisation of the extracts confirmed the antibacterial activity in the non-polar fraction, which could be terpenes. The results suggest a good prospect in using C. calcitrans against Vibrio and other bacterial species.
Conference paperJA Madrones-Ladja & MR de la Peña - In J Hylleberg (Ed.), Proceedings of the 10th International Congress and Workshop of the Tropical Marine Mollusc Programme (TMMP), 20-30 October 1999, 2000 - Phuket Marine Biological CenterTo relieve pressure on wild stock population, a hatchery technique for the window-pane shell, Placuna placenta Linnaeus has to be developed. A study was conducted to determine the suitable algal diet for P. placenta during gonad development and larval rearing. Sexually immature P. placenta broodstock were reared in the estuary or in tanks for four months. Tank-reared animals were fed daily mixture of Isochysis galbana (T-ISO) Parke and Tetraselmis tetrahele (G.S. West) at 100,000 cells/ml, 1:1 (100-I:T), or 200,000 cells/ml, 3:1 (200-3I:T) combinations. Monthly gonad histological examination showed that sexual maturity was attained by animals fed 200-3I:T diet after four months but not in 100-I:T. Estuary-reared broodstock had the highest gonad index among treatments after the first month, but did not reach sexual maturity until the end of the conditioning period. Sexually mature P. placenta from 200-3I:T fed-group spawned when exposed to UV light-irradiated seawater. One-day old larvae were reared in UV light-irradiated seawater until metamorphosis to plantigrade. Larvae were fed daily with monoalgal diet of I. galbana, T. tetrahele, or Chaetoceros calcitrans (Takano) at densities of 10,000-30,000 cells/ml. Larval settlement was observed in all diets after 14 days. Survival rate at metamorphosis was highest (12.60%) when diet of I. galbana was used, but lowest in T. tetrahele [5.1%) (P<0.05). Average shell length increment during the 14 days rearing period were 11.0, 11.38 and 9.92 µm day-1, for Isochrysis, Tetraselmis and Chaetoceros fed larvae, respectively.
Low-cost production of the marine thraustochytrid isolate, Schizochytrium sp. LEY7 as larval live feed enrichement for the mangrove snapper, Lutjanus sp. G Ludevese-Pascual, M de la Peña, O Reyes & J Tornalejo - In CI Hendry (Ed.), Larvi ’13 – Fish & Shellfish Larviculture Symposium, 2013 - Laboratory of Aquaculture & Artemia Reference Center, Ghent UniversityThis study demonstrates the potential of low-cost production substrates in mass producing the Schizochytrium sp. LEY7 for maximum DHA production. High biomass yield was achieved by optimizing the culture conditions particularly the incubation temperature and salinity levels. Preliminary data on feeding trials have shown promising results and therefore confirmatory experiments need to be conducted to verify the results obtained.
ArticleNephroselmis clavistella D. G. Faria et S. Suda sp. nov. is collected from coastal sand samples from the eastern and western coasts of Okinawa-jima Island, Japan. The description of the cultured strains is based on light and electron microscopic observations. The cultured strains are phylogenetically analyzed based on 18S rDNA sequences. The cells are remarkably right–left flattened and appear round or ellipse when viewed from their right or left side, and are ∼5.0 μm in diameter. The posterior flagellum curved around the cell body at rest. A single, parietal, crescent chloroplast is yellowish green and contains one conspicuous eyespot in its anterior-ventral edge near the short flagellum base. A pyrenoid with one starch sheath is located dorsal of the chloroplast. The cells are divided by transverse binary cell division, as is common in other species of this genus. The cell body is covered with five types of scales, and among them four scale types are similar to Nephroselmis rotunda. The fifth scale type is a distinctive spiny and club-shaped stellate scale with 10 spines, four of the 10 spines extended ∼150 nm and each are slightly curved with a hook at the end, whereas six spines are club-shaped blunt ended. This scale morphology, an important taxonomic characteristic, has never been described before for the genus Nephroselmis. The cell’s morphology is distinctive from previously described Nephroselmis species, and its unique scale characteristics led us to name this newly proposed species “clavistella,” meaning club star.