Mannose or xylose based positive selection

Details Mannose or xylose based positive selection Mannose or xylose based positive selection

1995-10-03

1998-06-16

Robinson, Douglas W.

Multicellular living organisms and unmodified parts thereof and

Method of introducing a polynucleotide molecule into or...

The polynucleotide alters fat, fatty oil, ester-type wax, or...

800DIG40, 800DIG42, 800DIG56, 4351723, 4352404, 435233, 435194, 536 232, 536 237, C12N 1529, C12N 1582, C12N 1531, A01H 500

Patent

active

057673780

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a method for selecting genetically transformed cells into which a desired nucleotide sequence has been incorporated by providing the transformed cells with a selective advantage. The selective advantage possessed by the transformed cells may be due to their enhanced capacity, relative to non-transformed cells, to utilize an added compound as a nutrient, growth factor or energy source.
It is known that when genetic material is to be introduced into a population of cells by transformation, only a certain number of the cells are successfully transformed. Identification and separation of the transformed cells has traditionally been accomplished using "negative selection", whereby the transformed cells are able to survive and grow, while the non-transformed cells are subjected to growth inhibition or perhaps even killed by a substance which the transformed cells, by virtue of their transformation, are able to tolerate.
For example, when a population of plant cells is transformed, selection of the transformed cells typically relies on the presence in the transformed cells of a "selection gene" which provides for antibiotic or herbicide resistance. The selection gene--which in itself may have no useful function in the transformed plant (and may in fact be undesirable in the plant) is coupled to or co-introduced with the desired gene to be incorporated into the plant, so that both genes are incorporated into the population of cells, or rather into certain of the cells in the population, since it is difficult, if not impossible, in practice to transform all of the cells. The cells are then cultivated on or in a medium containing the antibiotic or herbicide to which the genetically transformed cells are resistant by virtue of the selection gene, thereby allowing the transformed cells to be identified, since the non-transformed cells which do not contain the antibiotic or herbicide resistance gene--are subjected to growth inhibition or are killed.
These negative selection methods have certain disadvantages. For example, the non-transformed cells may die because of the presence of antibiotics or herbicides in the growth medium. As a result, when the population of cells is a coherent tissue there is a risk that not only the non-transformed cells but also the transformed cells may die, due to the fact that the death of the non-transformed cells may cut off the supply of nutrients to the transformed cells or because the damaged or dying non-transformed cells may excrete toxic compounds.
Another disadvantage of negative selection is that the presence of an unnecessary gene, for example providing for antibiotic resistance, may be undesirable. There is concern among environmental groups and governmental authorities about whether it is safe to incorporate genes coding for antibiotic resistance into plants and microorganisms. This concern is of particular significance for food plants and for microorganisms which are not designed to be used in a closed environment (e.g. microorganisms for use in agriculture), as well as for microorganisms which are designed for use in a closed environment, but which may accidently be released therefrom.
A further disadvantage of negative selection is that plant tissues or cells treated with toxic substances become more susceptible to bacterial infection. This is a problem when Agrobacterium is used as a transformation vector, because the treated tissues or cells sometimes become overgrown with the bacteria even though antibiotics are used to prevent bacterial growth.
In addition, selection of cells or tissues using negative selection requires precise timing of expression of the introduced genes in relation to the selection process. If the transgenic cells are treated with a toxic compound before the detoxifying gene is expressed or before enough gene products are produced to ameliorate the action of the toxic compound, both the transgenic and the non-transgenic cells will be killed If selection is performed too late, the selection of transgenic cells or tissues

REFERENCES:
patent: 4857467 (1989-08-01), Sreekrishna et al.
Napoli et al. Introduction of a Chimeric Chalcone Synthase Gene into Petunia Results in Reversible Co-Suppression of Homologous Genes in trans. The Plant Cell, vol. 2, 279-289, Apr. 1990.
Piruzyan et al. E. coli glucose isomerase gene expression in transgenic plants. Chemical Abstracts, vol. 110 No. 25, p. 173 abstracts No. 226554, 1989.
Mjles et al. Nucleotide Sequence and transcriptional start point of the phosphomannose isomerase gene of E. coli. Gene, 32 (1984), 41-48.
Posno et al. Complementation of the Inability of Lactobacillus Strains To Utilize D-Xylose Catabolism-Encoding Genes of Lactobacillus pentosus. Applied and Environmental Microbiology, pp. 2764-2766, Sep. 1991.
Watkins et al. Inhibition of Pear Fruit Ripening by Mannose. Plant Physiol. (1987) 85, 56-61.
Smith et al. Antisense RNA inhibition of polygalcturonase gene expression in transgenic tomatoes. Natur vol. 334, pp. 724-726, 25 Aug. 1988.

Affiliated with

Also associated with

Rating

Mannose or xylose based positive selection does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Mannose or xylose based positive selection, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mannose or xylose based positive selection will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1727675