training - consulting - facilitating

get answers to some common questions

Genetically Modified Organisms (GMO)

What is a GMO?

Evolution is the process of genetic modification. Natural genetic modification has been occurring since organisms developed the ability to replicate themselves and give rise to new forms of life. In this sense, all species today are genetically modified organisms (GMOs).

The common usage of the term ‘GMO’ (or GM) is for organisms that have been engineered through the use of ‘gene technology’.  Advances in biotechnology enable the precise manipulation of genetic material.  These new scientific techniques (commonly referred to as ‘gene technology’ or ‘genetic engineering’) involve the inclusion (or deletion) of one or more genes that changes an organism’s characteristics.

DNA

Deoxyribonucleic acid (DNA) is the genetic code of information for what an organism will look like and how it will work.  It contains the instructions for the development and functioning of all living organisms (with the exception of RNA viruses).  DNA consists primarily of two long chains (polymers) made up from four nucleic acids (nucleotides or ‘nucleobases’): Guanine (G), Cytosine (C), Adenine (A) and Thymine (T).  Phosphate and sugar molecules bond with the nucleotides to provide a ‘backbone’ upon which a ‘sequence’ of the nucleotides is formed.

When two strands of nucleotide sequences are interlocked through ‘base pairing’ they form the ‘double helix’ structure of DNA.  Because A can only bond with T, and G can only bond with C, the DNA strands are ‘complementary’ to each other. 

For example, if a nucleotide sequence on one strand is GCAT, then the ‘complementary’ nucleotide sequence (base pairing) will always read CGTA (see diagram on right).  Because the phosphate and sugar molecules of the backbone bond asymetrically, any sequence of nucleotides also has ‘direction’, with the complementary strand being ‘anti-parallel’ to that  direction.

DNA is found in nearly all cells and is bundled up into structures called chromosomes.  Enzymes compact and organise the DNA, guiding the interactions between DNA and other proteins to control which parts of the DNA are transcribed and expressed.

Gene transcription and expression

Sequences of nucleotides that code for a type of protein or Ribonucleic acid (RNA) with a functional role in an organism are called ‘genes’.  A single strand of nucleotides that is a copy of a gene taken from the DNA is called ‘messenger RNA’. The double strand DNA stores the gene information but the single strand mRNA copies direct the synthesis of proteins required for organisms to grow and function.  All cellular organisms use mRNA for this purpose.  Some viruses (non-cellular organisms) only have RNA, to also store their genetic material.   Viruses infect cells so they can use the host-cell RNA copying machinery to replicate themselves.  The process of copying genes from DNA into the related mRNA is called ‘transcription’.

For transcription to occur, an enzyme called Helicase unwinds sections of the DNA double helix so that another enzyme called RNA Polymerase can ‘read-off’ the nucleotide sequence and construct a ‘complementary’ mRNA copy of genes from the DNA ‘template’ strand.  mRNA transcription units encode for at least one gene.

find out more about gene technology science by

DNA double helix

go to OGTR website

go to OGTR website

complementary, anti-parallel strands

Australian laws require foods with more than 1% or more GM ingredients to be labelled

The complementary, anti-parallel mRNA strand can now be used as a template to construct copies of the gene(s).  Depending on the gene purpose, the mRNA may be translated into protein, ribosomal RNA, transfer RNA or other components of assembly processes that direct or regulate an organism’s growth and function.

Each organism has it’s own unique combination of DNA, called a ‘genotype’ (unless it is a ‘clone’).  Clones are organisms that have exactly the same DNA.  Some genes can be highly ‘conserved’ across species because they code for functions that most organisms require, so we share significant amounts of DNA with many other organisms.  Various estimates are often cited about the percentages of genetic material humans share with chimpanzees, worms, fruit flies and even bananas.

Because all living organisms have inherited the same fundamental system of genetic information storage, retrieval and replication, the potential exists for genes to interchange between organisms through subsequent generations - the process of evolution. New genetic combinations either confer advantage and are replicated or they become redundant and are deleted.  Humans have been using selective breeding of animals and plants for millennia and selecting them for desirable traits for our benefit.

Biotechnology now enables greater flexibility, precision and shorter time spans for this process to occur.  Genes can be cut out of one DNA strand and inserted into another strand of DNA  with high precision. This enables the transfer of genes more quickly between organisms that could be conventionally bred together (called ‘Cisgenesis’) but also enables the transfer of genes between organisms that could not be conventionally bred together (called ‘Transgenesis’).   Biotechnology can also be used for ‘gene therapy’: the ability to insert, alter or remove genes to treat disease.

Techniques used for transferring DNA from one organism to another include:

1. •use of attenuated (modified) viruses (e.g. adenovirus)
   

2. •physically inserting extra DNA into the nucleus of the intended host using a microsyringe
   

3. •shotgun technique using coated gold or tungsten nanoparticles fired at cells
   

4. •Agrobacterium transfer of DNA plasmids into plant cells
   

5. •electroporation (pulsed electric current)
   

Marker genes are included with the inserted DNA so researchers can select for cells that have successfully taken up and express the new DNA.  These cells are then grown out to evaluate if the transfer has been successful.

Gene technology benefits

Gene technology benefits include:

1. •improved basic research efficiency in biology and medicine
   

2. •greater flexibility and shorter time spans in the modification of agricultural crops and animals to incorporate resistance to pests and diseases, herbicide tolerance, improve nutrition, alter ripening of fruit or the timing and duration of flower production
   

3. •efficiency in modification of micro-organisms to produce medicines and therapeutic products such as insulin and vaccines
   

4. •improved diagnosis and treatment of diseases such as cancer, diabetes, malaria and influenza
   

5. •greater opportunity for industrial uses such as production of enzymes for use in food processing and paper pulp production and biological leaching of minerals
   

6. •bio-remediation, e.g. use of micro-organisms to decompose toxic substances and clean-up industrial sites or environmental accidents
   

Gene technology risks

Most GMOs have the potential to reproduce, multiply and spread in the environment after they are released.  Genetic modifications could give GM plants, animals or microorganisms a competitive advantage that would allow them to increase in numbers, spread in the environment and displace natural species.

The novelty of GMOs, the fact that - like all plants - they will continue to reproduce after release, the complexity of natural environments and ecosystem processes, and the unknown evolutionary fate of inserted genes all need to be considered in predicting environmental impacts.

Risk assessments for GMOs consider the following factors:

1. •is the gene related to the species being modified - is it an extra copy, a modification of the organism's own genetic material or is it transgenic
   

2. •will the new or modified gene cause the modified organism to become toxic or impact on the consumer, such as introducing an allergen
   

3. •will the new or modified gene increase the environmental 'fitness' of the modified organism
   

4. •is the modified organism exotic or native to Australia, and does it have pest, weed, or native relatives
   

5. •could the modified organism transfer the gene to any other closely related, non-GMO species through natural reproductive processes, or to distantly related species through other processes or accidents
   

6. •how much of and where will the GMO be released and how will it be managed and monitored
   

7. •will the GMO persist beyond intended areas and what will be the environmental fate of any new substances produced by the GMO?
   

Organic farmers are concerned about the spread of GMOs as their status as organic farmers is dependent upon their operations being ‘GMO free’.  Drift of genetic material from neighbouring farms using GMOs may ‘contaminate’ their crop and risk their organic certification.

Some activist organisations are ideologically opposed to gene technology and allege a broad range of risks from food safety to the environment.  Emotive descriptions such as ‘Frankenstein Foods’ are used to evoke fear of GMOs among the general population, with regard to the technology risks.

GMO foods have been available in some countries for over 15 years and to date there has been no adverse effects reported from the consumption of those foods.

There are no GMO fresh produce crops grown in Australia and sold to the public - at this point in time.  There are many in development.

The environmental risks from GMOs vary, depending on the characteristics of, and the interactions between, the organism, the trait introduced through the gene, and the environment. For this reason, risk assessments need to be conducted on a case-by-case situation.

Gene technology regulation in Australia

Gene technology is regulated by the Federal Government Office of the Gene Technology Regulator (OGTR), within the Department of Health and Ageing portfolio, under the Gene Technology Act 2000.

Under Australian legislation, any 'intentional release' of a GMO into the environment requires a licence. Before issuing a licence, the OGTR must prepare a risk assessment and risk management plan, and seek advice on it from the Environment Minister. Written public submissions by interested parties are also invited.

The OGTR GMO Record provides a full list of GMOs in Australia that have been approved for intentional release into the open environment.

GMO products for human consumption are also assessed by Food Standards Australia New Zealand as to whether they carry any substantive greater risks than the non-GM equivalent product. These are identified in Standard 1.5.2.