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Unintended Effects of Genetic Manipulation

A Project of The Nature Institute

Project Director: Craig Holdrege

Tilapia fish engineered for transgenic expression of growth hormone had deformed heads and backs, atrophied gonads, and lower mineral content.

Manipulated Organism: Tilapia (Oreochromis niloticus).

Inserted Transgenes: Tilapia growth hormone gene, with expression controlled by the beta-actin promoter from medaka fish.

Goal of This Study: Compare the growth of tilapia expressing the growth hormone transgene with their non-GM siblings.

Intended Effect: At 87 days post hatching, the average body weight of the GM fish was nearly 3 times that of the non-GM fish. By 147 days, the GM fish had reached market weight (165 g), while the non-GM fish required an additional 90 days to reach that size.

Results of This Study: Numerous morphological and compositional differences were observed when the fish were harvested (at the same weight but months apart), including:
Source: Lu, J., J. Li, Y. Furuya, G. Yoshizaki et al. (2009). "Efficient Productivity and Lowered Nitrogen and Phosphorus Discharge Load from GH-Transgenic Tilapia (Oreochromis niloticus) under Visual Satiation Feeding," Aquaculture vol. 293, pp. 241-7.

Author Affiliations: Tokyo University of Marine Science and Technology, Japan.

Funding: Japanese Ministry of Education, Science, Sport and Culture.

Product Status: Not on the market as of 2009.

Copyright 2009 The Nature Institute.

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