Yazar "Langdon, Chris" seçeneğine göre listele

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    Complex microparticles for delivery of low-molecular weight, water-soluble nutrients and pharmaceuticals to marine fish larvae
    (Elsevier, 2007) Langdon, Chris; Clack, Brendan; Onal, Urnur
    Most currently available microparticulate artificial diets for rearing marine suspension feeders, including larval fish, are not effective in retaining low-molecular weight, water-soluble (LMWS) nutrients and other materials [Lopez-Alvarado, J., Langdon, C.J., Teshima, S., Kanazawa, A., 1994. Effects of coating and encapsulation of crystalline amino acids on leaching in larval feeds. Aquaculture 122, 335-346; Baskerville-Bridges, B., Kling, L.J., 2000. Development and evaluation of microparticulate diets for early weaning of Atlantic cod, Gadus morhua, larvae. Aquae. Nutr. 6, 171-182]. Rapid leaching losses occur as a result of high surface-to-volume ratios and the porosity of the matrix or walls of the particles [Langdon, C.J., 2003. Microparticle types for delivery nutrients to marine fish larvae. Aquaculture 227, 259-275]. In order to address this problem of high leakage losses, a novel complex particle type was developed consisting of LMWS incorporated in lipid beads that are then bound, with other nutrients, in a matrix of the water-insoluble protein zein. A spray method for preparing lipid beads was developed to increase the concentration of incorporated core material as well as to reduce losses due to leakage from beads suspended in water. It was possible to prepare lipid spray beads (LSB) that delivered 8.5% of their dry weight as glycine after I-h suspension in water, resulting in free amino acid concentrations similar to those of commonly used live feeds for fish larvae, such as rotifers and Artemia; however, this delivery efficiency was reduced to 1.2% glycine for complex particles made up of 30% w/w glycine-containing LSB and other dietary nutrients. Further experiments are required to determine if complex particles can replace living feeds for the early larval stages of marine fish species. (C) 2007 Published by Elsevier B.V.
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    Diet Size Preference of Zebrafish (Danio rerio) Larvae Fed on Cross-Linked Protein-Walled Capsules
    (Mary Ann Liebert, Inc, 2016) Onal, Umur; Langdon, Chris
    To optimize diet particle size for ingestion by zebrafish larvae, Danio rerio, a series of diet selection experiments were carried out using two different length classes: 5-day-old, first feeding larvae with a mean standard length (MLs) of 3.8mm and 15-day-old larvae with MLs of 5.2mm. For this purpose, crosslinked protein-walled capsules with five different size classes (20, 21-45, 46-75, 76-106, and 107-212m) were used in selection experiments. A particle size selection model was then developed after accounting for both rate of loss of capsules in the water column and their ingestion by larvae. Results indicated that concentration of larger particles in the water column decreased rapidly and less than 20% of capsules larger than 75m were available for the larvae after 30min. Zebrafish larvae accepted a wide range of particle sizes, but larvae preferred particles much smaller than the maximum size they could ingest. While first feeding larvae preferred 21-45m capsules, 15-day-old larvae preferred capsules in the 47-75m size range. A better understanding of the behavior of small-sized food particles in the water column and their acquisition by fish larvae is important to optimize feeding protocols in successful larvae culture.
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    Ontogeny of the digestive tract of larval percula clownfish, Amphiprion percula (Lacepede 1802)
    (Wiley, 2008) Oenal, Umur; Langdon, Chris; Celik, Ihsan
    An understanding of the development of the digestive system of marine fish larvae is of critical importance in determining optimal feeding regimes for their culture. The present study provides information on the histomorphological development of the digestive system of clown fish, Amphiprion percula, larvae during the first month of life. Before hatching, clownfish larvae possess an alimentary tract, liver and pancreas with absorptive and digestive capabilities. The yolk sac is completely consumed within 5-7 days at 25 degrees C. Clownfish larvae readily accept rotifers after hatching and a complete dietary shift from rotifer to Artemia can be accomplished at 10 days after hatch (DAH). Gastric glands in the stomach first develop 11 DAH and proliferate by 15 DAH. Both non-staining vacuoles (NSV) and supranuclear inclusion vesicles (SIV) appear at 11 DAH in the midgut and hindgut respectively. Pinocytosis and extracellular digestion coexist for about 2 weeks after hatching. While SIV disappeared completely at 25 DAH, NSV continued to be a prominent feature of the midgut during the first month.
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    Potential delivery of water-soluble protein hydrolysates to marine suspension feeders by three different microbound particle types
    (Elsevier Science Bv, 2009) Onal, Umur; Langdon, Chris
    Spray-dried zein particles (SDZP), spray-water zein particles (SWZP) and gelatin-alginate beads (GAB) were prepared containing a defined dietary mixture and their performances were compared for delivering the soluble fraction of protein hydrolysates. Measures of performances of these three different microbound particle (MBP) types included inclusion, encapsulation, retention and delivery efficiencies in addition to T-50 (time to 50% retention) values. SDZP had higher inclusion (IE) and encapsulation efficiencies (EE) compared to those of SWZP and GAB. A maximum IE of 66.60% and EE of 10.01% were achieved for SDZP. Although elimination of water from the manufacture process resulted in significantly higher inclusion and encapsulation efficiencies for SDZP, retention efficiencies and leakage profiles of all particle types were similar and followed a biphasic pattern with an initial burst release followed by a slower phase. Delivery of hydrolysates by SDZP was greater than for other MBP types with fifty percent of the initial hydrolysate retained after 36 min suspension in water. SDZP provides a more effective delivery vehicle for soluble protein hydrolysates than the other MBP types evaluated in this study. This, in turn, may help overcome limitations in the delivery of water-soluble nutrients and formulation of artificial diets for marine fish larvae and other suspension feeders. (C) 2009 Elsevier B.V. All rights reserved.