Conducted Studies

Nature 342, 76 - 78 (02 November 1989); doi:10.1038/342076a0

Production of Antibodies into Transgenic Plants

ANDREW HIATT, ROBERT CAFFFERKEY & KATHERINE BOWDISH

Department of Molecular Biology, The Research Institute of Scripps Clinic, 10666 North Torrey Pines Road, La Jolla, California 92037, USA


In this lab, complimentary DNA's that were derived from a mouse hybridoma messenger RNA were used o transform tobacco leaf segments followod by regeneration of mature plants. Plants that expressed single gamma or kappa immunoglobulin chains were crossed to yield progeny in which both chains were expressed simultaneously. A functional antibody accumulated to 1.3% of total leaf protein in plants expressing full-length cDNAs containing leader sequences.Binding of the antigen was similar to the hybridoma-dervided antibody. Transformants having γ- or κ- chain cDNAs without leader sequence gave poor expression of the proteins. The results demonstrated that production of immunoglobulins and assembly of functional antibodies occurs very efficiently in tobacco (Andrew). 

Andrew, H. (n.d.). Retrieved from http://www.nature.com/nature/journal/v342/n6245/abs/342076a0.html

The Gene Gun

Gene guns are essentially used to inject genetic information into the tissues of plants to physically transform them. Transformation is the genetic alteration of a cell due to the incorporation or uptake of foreign genetic material(Standard). This then alters the genetic makeup of the plant.

The gene gun can be used on tissue culture cells or seeding of any species. The gene gun is a method that works by shooting DNA into the plant cells. Microscopic gold or tungsten particles are coated with hundreds of copies of the gene(s) to be introduced. (Deana)

With a gene gun, heavy microscopic particles (tungsten, gold, titanium) are coated with DNA or RNA. The particles are inserted into a plant tissue at a very high velocity the puncture the cell membrane. The particles penetrate the cells into the cytoplasm or the nucleus. The gene gun apparatus has a plate that allows only DNA-coated particles to accelerate towards the target tissue to facilitate accurate transformation. Transformation is any alteration in the genome of a cell after the uptake, incorporation, or expression of foreign genetic material (Standard).

Fig. 4

Gene gun animation http://passel.unl.edu/pages/animation.php?a=GeneGun.swf

Ethics

The introduction of genetically modified crops is a highly controversial topic in the UK, parts of Europe and in other parts of the world. The possibility of these genetically altered crops forming a large proportion of the plants grown by farmers in the US and Europe within the next decade has brought forth many reactions ranging from outrage and anger, and unease. The introduction of the crops however has been greeted with near-indifference by consumers in the US and Canada.

There are three main types of principle that are relevant to the evaluation of policies or 
practices:

Will the technology promote the general welfare by making for improved food safety or
reducing the use of chemical pesticides in agriculture? Or does the technology pose
unknown risks for consumers and the environment that we would be wise not to run if
we are concerned about the general welfare?
• What implications does the technology have for the rights of consumers, for example
the right to be informed about the food one is eating?
• What implications does it have for the rights of scientists to be free to conduct their
research in ways that protect their intellectual integrity?
• Finally, we can ask questions derived from a concern with the principle of justice. Who
will be the principal beneficiaries from the introduction of the new technologies and
what obligations do they have to compensate the losers?


(Nuffield Council on Bioethics)

 Some people view genetically modified crops as "unnatural". Other argue that it is unethical to treat nature in an industrial fashion. These concerns state that the environment is an object of ethical concern, regardless of how the environment affects the interests of humans and other animals.

Fig. 3

Locating Genes for Plant Traits

In the transgenic process, the most limiting step is identifying and locating genes for certain desired traits. Traits of interest include helping to enhance yield potential (amount of product), improve stress tolerance and to modify chemical properties of the harvested product. Not only must scientists identify certain genes, but they must also know how it interacts with other genes that are active in the same biochemical pathway. A few changes to the isolated gene must be made for it to be successfully inserted into the plant.

First off, a promoter sequence must be added to the gene. This sequence acts as an on/off switch that control where the gene is expressed. these genes must also sometimes be modified. For example, the Bt gene for insect resistance has a greater amount of A-T nucleotide pairs than plants, which tend to have more C-T pairs. The A-T nucleotides can be substituted for with C-T pairs in a way that doesn't quite change the amino acid sequence. This leads to a greater protection of the inserted gene in plant cells. A terminal sequence must also be added to signal when the end of the gene sequence has been reached. Lastly, a selective marker gene is inserted in order to identify plant cells which have successfully integrated the transgene.

Fig. 2

Intro To Transgenic Plants

Transgenic Plants!!!!!

A transgenic plant contains a gene/genes which have been artificially inserted rather than the plant acquiring them through pollination. the gene that is inserted is known as the transgene. The transgene may come from another plant, or even from a different species!

The plants that have been genetically modified are called genetically modified crops.

 Fig. 1