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dc.contributor.advisorUscian, John M.
dc.contributor.authorGuerrero-Bravo, José E.
dc.description.abstractThis study evaluated the effect of five diets, differing from one another based upon ratio of raw soybean/processed soybean content, upon both biomass production and intestinal protease activity in gray tilapia (Oreochromis niloticus) and red tilapia (Oreochromis hornorum). The tilapia were maintained for 5 weeks in a Lajas’ Aquaculture Facility pond, Lajas, Puerto Rico. This pond contained 5 separate cages and each cage contained 16 male tilapia, 8 of which were gray and 8 of which were red. These fishes were provided with one of the following five diets (i.e., 0:4, 1:3, 2:2, 3:1, or 4:0 for raw soybean/processed soybean protein dietary component). At the end of the feeding period, the following were determined: 1) weight, 2) total intestinal protease activity (determined by fluorometric assay), 3) amount of intestinal protease activity attributable to the enzyme trypsin, 4) feasibility of purifying and characterizing trypsin from red or gray tilapia, 5) in vitro examination of how the addition of processed soybean homogenate affects intestinal protease activity, and 6) SDS-PAGE zymogram visualization of the effect of increased processed soybean homogenate on total intestinal protease activity. Although an increase in biomass >5% for gray tilapia and >21% for red tilapia was observed, a linear correlation between increased raw soybean feed content and biomass production was not observed. The in vitro assays revealed that intestinal proteases of both red and gray tilapia are inhibited by processed soybean homogenate. This effect was greatest for gray tilapia. Trypsin was partially purified from both tilapia species and found to display a pH optimum of 8.0, highest catalytic rate at 50 oC, and a molecular weight of approximately 23 kDa. In addition, in vitro soybean trypsin inhibitor analysis revealed that 82-86% of the total intestinal protease activity was attributable to trypsin, a finding similar to that from similar analysis of other fish species.en_US
dc.description.abstractEste estudio evaluó el efecto de cinco diferentes dietas basadas en el contenido de soya cruda/soya procesada sobre la producción de biomasa y la actividad de proteasas intestinales en tilapia gris (Oreochromis niloticus) y tilapia roja (Oreochromis hornorum). Las tilapias fueron mantenidas por 5 semanas en un lago de las Instalaciones de Acuacultura de Lajas, Puerto Rico. Este lago contenía 5 jaulas separadas, cada una contenía 16 tilapias machos, 8 de los cuales eran grises y 8 rojas. Estos peces fueron sometidos a una de las cinco diferentes dietas de soya (i.e., 0:4, 1:3, 2:2, 3:1, o 4:0 relación soja cruda/soja procesada como componente de proteína en la dieta). Al final del periodo de alimentación se determinó: 1) peso grupal, 2) actividad total de proteasas (mediante ensayo fluorométrico), 3) cantidad de actividad de proteasas intestinal atribuible a tripsina, 4) purificación y caracterización parcial de tripsina en tilapia roja y gris, 5) examinación in vitro de cómo la adición de homogenato de soya procesada afecta la actividad de proteasas intestinales, y 6) zimogramas en SDS-PAGE para visualizar el efecto del incremento de homogenato de soya procesada sobre la actividad total de proteasas. Se observó un aumento en biomasa > 5% para tilapia gris y >21% para tilapia roja; aunque no se observó una correlación lineal entre al incremento en soya cruda y la producción de biomasa. Los ensayos in vitro demostraron que las proteasas intestinales de ambas especies son inhibidas por el homogenato de soya procesada. Este efecto fue mayor para tilapia gris. Tripsina fue parcialmente purificada de ambas especies de tilapia y ambas enzimas mostraron un pH óptimo de 8.0, la mayor actividad catalítica a 50 oC, y un peso molecular de aproximadamente 23 kDa. Además, el análisis in vitro con el SBTI reveló que del 82-86% de la actividad total de proteasas intestinales fue atribuible a tripsina, resultado similar a lo encontrado en los análisis de otras especies de peces.en_US
dc.subjectGray tilapia (Oreochromis niloticus)en_US
dc.subjectRed tilapia (Oreochromis hornorum).en_US
dc.subjectBiomass productionen_US
dc.subjectIntestinal protease activityen_US
dc.subject.lcshNile tilapia--Feeding and feedsen_US
dc.subject.lcshTilapia--Feeding and feedsen_US
dc.subject.lcshSoybean as feeden_US
dc.subject.lcshProtease inhibitorsen_US
dc.titleFluorescence-based assessment of total protease activity/trypsin as a function of variable soybean content in fines fed to the gray tilapia (Oreochromis niloticus) and the red tilapia (Oreochromis hornorum)en_US
dc.rights.licenseAll rights reserveden_US
dc.rights.holder(c) 2007 José E.Guerrero-Bravoen_US
dc.contributor.committeeSantos, Carlos J.
dc.contributor.committeeMontalvo, Rafael
dc.contributor.representativePérez Muñoz, Fernando J.
dc.contributor.collegeCollege of Arts and Sciences - Sciencesen_US
dc.contributor.departmentDepartment of Biologyen_US

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