For centuries, mankind has been using traditional modification methods, such as selective breeding and cross-breeding, to produce plants and animals having certain desired traits. Most of the foods available in the market today have been produced through traditional breeding methods.
However, it is to be noted that modification of plants and animals through traditional methods is time-consuming and, often, produces mixed results, often with undesirable traits accompanying the desired ones.
These limitations could be overcome with the advent of what is known as recombinant DNA (rDNA) technology synonymously called genetic engineering. Interestingly, genetically engineered salmon has been a source of delight as well as doubt.
What is rDNA technology?
rDNA technology involves artificial introduction of genetic material from one organism into the genome of another organism, and subsequent replication and expression of the transferred genetic material by the recipient organism, which is now called transgenic. The technology was developed in the 1970s through the work of Paul Berg and Stanley Cohen of Stanford University, and Herbert Boyer of University of California, San Francisco.
The development of rDNA technology was followed by its extensive applications to genetically modify different kinds of organisms – starting from bacteria to plants and animals. In contrast to the traditional breeding methods, changes in these genetically modified organisms (GMOs) could now be brought about in a more specific way and in a shorter period of time.
GMO products emerge
The first consumer GMO product developed through genetic engineering was human insulin which was approved in 1982 by US Food and Drug Administration (US FDA) to treat diabetes. In early 1990s, scientists in China first commercialized genetically modified tobacco and, in 1994, the US market saw the first GMO tomato having the property of delayed ripening.
The first transgenic fish was produced in China in the mid1980s. More than 50 species of fish have been modified by genetic engineering ever since. Most of these transgenics have been, however, used for laboratory research.
The first transgenic fish was produced in China in the mid1980s. More than 50 species of fish have been modified by genetic engineering ever since. Most of these transgenics have been, however, used for laboratory research. Microinjection and electroporation of heterologous DNA (transgene) into newly fertilized eggs have been proven to be the most efficient methods of gene transfer in fish systems.
Commercialization of genetically engineered salmon
Despite the fact that fish is an important protein source for the majority of world population and, with continuously increasing demand, ocean fishery is under severe stress, commercialization of transgenic fish has been relatively late. In the past decade, there have been some steps forward in this direction, but associated with controversies and resistance.
Presently, the fish in the center of attention is Atlantic salmon. In 1992, the development of an “all fish” growth hormone chimeric gene construct, using an antifreeze protein gene promoter from ocean pout and chinook salmon growth hormone gene, was published [Biotechnology (1992) 10:176-181]. It was reported that, after one year, the transgenic fish was on an average 2 to 6-fold larger than its non-transgenic counterpart.
Genetically modified (GM) salmon has been commercialized by AquaBounty Technologies, a company based in Maynard, Massachusetts. In November 2015, responding to an application by the company, the US FDA approved the first genetic modification in an animal (salmon) for use as food. Six months later GM salmon was approved for consumption in Canada and by the middle of 2017, it reached the Canadian dinner table.
Controversies and resistance
Resistance to the AquaBounty salmon was greater in the US. Nevertheless, after going through some intense debate accompanied by litigation, it was available in the US market for the first time in June 2021.
Controversies over GM salmon, or, for that matter, all GMO food, persist and, certainly, are not going to die down. Whether or not to consume such food – the question does not have a simple “yes” or “no” answer. The arguments, in favor or against, only reverberate the entire history of technological developments which came about weighing intended benefits against possible hazards. The momentum towards GMO food is most unlikely to stop – this is a reality. What are needed alongside the forward movement are unwavering vigilance and judicious regulations.