Induction of Triploidy and Tetraploidy in Nile Tilapia, Oreochromis niloticus (L.) |
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| Authors: | Abdel-Rahman A El Gamal Kenneth B Davis Jill A Jenkins E Les Torrans |
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| Institution: | Central Laboratory for Aquaculture Research, Abbassa, Abou Hammad, Sharkia, Egypt;Department of Biology, Ecological Research Center, The University of Memphis, Memphis, Tennessee 38152 USA;The Southeastern Fish Cultural Laboratory, National Biological Service, U. S. Department of the Interior, Marion, Alabama 36756 USA |
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| Abstract: | Abstract.— Induction of triploidy and tetraploidy in Nile tilapia, Oreochromis niloticus , was investigated by heat shock, cold shock, hydrostatic pressure, and/or chemicals (cytochalasin A, B, and D). Additionally, efficacy of combined protocols was determined. Heat shock 10 min after fertilization induced triploidy when incubation temperature was 24 C but not when incubation temperature was 31 C. Heat shock of 40–41 C at 4–6 min after fertilization was effective in inducing up to 100% triploidy with hatchability similar to controls. Cold shock at 13 C for 45 min five min after fertilization induced 85–100% triploids. Heat shock and multiple heat shocking were the most effective treatments for the induction of tetraploidy. Two heat treatments of 41 C applied at 65 and 80 min after fertilization for 5 min each produced approximately 80% tetraploidy in hatched fry. Immersion of fertilized eggs in cytochalasin A, B, or D at concentrations up to 10 μg/L applied at various times and durations was ineffective in inducing triploidy or tetraploidy. |
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