Evaluation of Transgenic approaches for the Production of Fish and Shellfish

In the aquaculture industry¡ most of the improvements in fish farming have been achieved by traditional breeding methods. In the past two decades¡ there has been a marked progress in employing recombinant DNA technology and genetic engineering to produce transgenic fish with desirable traits¡ such as increased growth rate and disease resistance. Fish and shellfish are particularly suitable for transgenic manipulation¡ because most species reproduce by external fertilization. Growth hormone gene has been commoving considered in gene transfer technology because it’s over expression could result in dramatic increases in performance of aquaculture stocks¡ such as in Coho salmon by 11-folds. A number of methods have been used for transferring genes into fish eggs. Microinjection is the preferred method; the integration rates of transgenes are generally low though. A number of fusion genes¡ containing retrovirus sequences which direct integration¡ have been developed to enhance integration of transgenes. Mass gene transfer methods are also being developed. These include lipofection¡ particle bombardment¡ and electroporation of embryos and sperm cells. These methods are potentially useful for marine organisms such as crustaceans and molluscs as well as fish. This review paper will discuss recent advances in biotechnology research and different gene transfer methods¡ advantage and disadvantage of these methods¡ specifically in regards to the manipulation of genes¡ for enhanced cultivation of fish and invertebrates.