Transgenesis In Fish

c) Lipofection

Liposome-mediated gene transfer is based on the encapsulation of vector DNA into a synthetic phospholipid bilayer, which fuses with the cell membrane of the target cell, introducing the foreign DNA into the cell. The positively charged lipids and liposomes are thought to improve transgene delivery mainly through binding to and condensing negatively charged DNA, forming a complex called lipoplex in which the DNA is protected against extracellular degradation.

d) Sperm mediated gene transfer (SMGT)

It is based on the intrinsic ability of sperm cells to bind and internalize exogenous DNA molecules and to transfer them into the oocyte at fertilization. Thus, sperm cells are used as vectors for transmitting their own and also

Growth enhancement Experiments demonstrated that growth can be enhanced through transgenesis from 10% up to an incredible 30-fold in many conditions (Dunham, 2011). Gene constructs containing fish GH sequences driven by non-piscine promoters elicited growth enhancement in transgenic carp, catfish, zebra fish and tilapia. For instance, in transgenic Atlantic salmon, the average increase of the transgenic fish was 2 to 6 fold and the largest transgenic fish was 13 times that of the average non-transgenic control.

2. Disease resistance

Momentum is being gained in transgenic enhancement of disease resistance. One potential mechanism for improving disease resistance is production of transgenic aquatic organisms containing lytic peptide genes such as Cecropins. These are small cationic peptides found originally in the moth Hyalophora cecropia. Administrations of cecropins derivatives confer protection against infection with Edwardsiella ictaluria, a major pathogen of cultured catfish (Dunham et al., 2002). It killed several fish viral pathogens, infectious hematopoietic necrosis virus (IHNV), viral hemorrhagic septicemia virus (VHSV), snakehead rhabdovirus (SHRV) and infectious pancreatic necrosis virus

The power of the GFP (green fluorescent protein) transgenic fish has been quickly recognized and is actively used to investigate gene expression patterns, tissue/organ development, tissue-specific promoters/enhancers, cell lineage and migration, upstream regulatory genes etc. (Udvadia and Linney, 2003).

7. Transgenic Oncofish

In the past few years, the zebra fish has been advocated as a new cancer model (Stern and Zon, 2003) because the fish as a member of vertebrates have basically the same set of genes as human does and because the molecular mechanisms of gene regulation including carcinogenesis are assumed to be more or less identical between fish and human. These thoughts, in combination with the easy availability of large number of zebra fish and low cost of experiments, make the zebra fish a good model for cancer research.

Currently, the transgenic approach is used to generate tumor zebra fish by the overexpression of selected oncogenes and then used to further study molecular mechanisms of carcinogenesis (Langenau et al., 2003).These oncofish also have potential for future drug