Safety Evaluation of Transgenic Tilapia with Accelerated Growth

Abstract

Recent advances in modern marine biotechnology have permitted the generation of new strains of economically important fish species through the transfer of growth hormone genes. These transgenic fish strains show improved growth performance and therefore constitute a better alternative for aquaculture programs. Recently, we have obtained a transgenic tilapia line with accelerated growth. However, before introducing this line into Cuban aquaculture, environmental and food safety assessment was required by national authorities. Experiments were performed to evaluate the behavior of transgenic tilapia in comparison to wild tilapia as a way to assess the environmental impact of introducing transgenic tilapia into Cuban aquaculture. Studies were also conducted to evaluate, according to the principle of substantial equivalence, the safety of consuming transgenic tilapia as food. Behavior studies showed that transgenic tilapia had a lower feeding motivation and dominance status than controls. Food safety assessment indicated that tilapia growth hormone has no biological activity when administered to nonhuman primates. Furthermore, no effects were detected in human healthy volunteers after the consumption of transgenic tilapia. These results showed, at least under the conditions found in Cuba, no environmental implications for the introduction of this transgenic tilapia line and the safety in the consumption of tiGH-transgenic tilapia as an alternative feeding source for humans. These results support the culture and consumption of these transgenic tilapia.

Genetic Engineering of Fish, and Methods of Detection

“…for tilapia) or from another fish species. The evaluation of the safety of consuming tiGHtransgenic tilapia included a study of the effects of injection of recombinant tiGH into macaques, and a test of the in-vitro activity of tiGH on rabbit xiphoid cartilage bioassay [84]. From the results from both experiments the conclusion was drawn that tiGH had no effect on the metabolism of higher vertebrates and, especially, no biological activity in nonhuman primates.…”

Transgenic/Transgenic Modified Fish

“…for tilapia) or from another fish species. In the case of the transgenic GH fish, specific experimental evidence that teleost GH is not active in primates was obtained by Guillen et al [30]. Juvenile monkeys, Macaque fascicularis (macques) were injected with 1000 ng/kg of recombinant tilapia growth hormone per day for 30 days, equivalent to administering 70 g/day to a 70 kg human.…”

“…Juvenile monkeys, Macaque fascicularis (macques) were injected with 1000 ng/kg of recombinant tilapia growth hormone per day for 30 days, equivalent to administering 70 g/day to a 70 kg human. Guillen et al [30] have shown that blood parameters examined included hemoglobin, serum total proteins, blood glucose, packed cell column, total leukocytes, and total erythrocytes. Body weight, rectal temperature, heart rate, and respiratory rate were recorded daily.…”

“…Guillen et al [30] indicated that no histopathological or morphological changes were observed. Twenty-two humans were fed tilapia (transgenic hybrid Oreochromis hornorum) that contained and expressed tilapia GH transgene.…”

“…Levels of GH and insulin-like growth factors (IGF) expressed by transgenic GH salmon are not always outside the range or much greater than the upper limit of GH and IGF secretion for other fish, food animals, or humans. Guillen et al [30] also indicated that teleost fish GH and IGF are not bioavailable when orally ingested (cooked or raw, adequate cooking would denature the proteins) and even if they were totally bioavailable, the dose from one meal would only be a small fraction of total, daily, human production of GH and IGF. Growth hormone is not orally active in higher species, for example, fish GH is not bioactive in humans.…”