Tilapia fish engineered for transgenic expression of growth hormone
had deformed heads and backs, atrophied gonads, and lower mineral content.
Tilapia (Oreochromis niloticus).
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.
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:
The GM fish had larger heads and wider bodies. Some had deformed, even
fractured, backs and heads.
The viscera of the GM fish were 8% of their total body weight compared
with 6% for the non-GM fish (p < 0.01).
The gonads of the GM fish were strongly atrophied, comprising only 0.05%
of the total body weight compared with 1.0% for the non-GM fish.
The GM fish had a higher moisture content (77% versus 70%) and contained
significantly less calcium (Ca) and phosphorus (P). On a dry weight
basis, the GM fish had only 72% and 86% of the Ca and P, respectively,
of the non-GM fish at market weight. The authors interpret this fact
as indicating incomplete bone mineralization, which is consistent with
the observation of bone fractures in the GM fish.
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.
Tokyo University of Marine Science and Technology, Japan.
Japanese Ministry of Education, Science, Sport and Culture.
Not on the market as of 2009.
Copyright 2009 The Nature