Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Mendelian transmission, transgene dosage and growth phenotype in transgenic tilapia (Oreochromis hornorum) showing ectopic expression of homologous growth hormone.

Abstract

Transgenic tilapia (Oreochromis hornorum urolepis) were produced by the microinjection of a transgene containing the tilapia growth hormone (tiGH) cDNA under the regulatory sequences derived from the human cytomegalovirus (CMV) into early embryos. A male containing 1 copy/cell of the transgene was selected to establish a transgenic tilapia line. Genomic DNA was extracted from fin tissue and embryos and was analysed by PCR. The transgene was transmitted to F1-F4 generations in a Mendelian fashion. Biochemical analyses indicated lower levels of cholesterol, free alanine and aspartic acid in the muscle of transgenic fish compared with wild type tilapia. 6 transgenic homozygous (F2+/+), 8 transgenic heterozygous (F2-/+) tilapia and 14 non-transgenic siblings were maintained in the same pond for 3 months starting at 4 months of age and growth rate was recorded. Transgenic F2-/+ and F2+/+ progeny were 62 and 31% heavier than non-transgenic siblings at 7 months of age (P = 0.005 and P = 0.07, respectively), suggesting a transgene-dosage effect.