Agricultural Biotechnology Strategies for National Competitiveness (1987) / Chapter Skim
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2. Scientific Aspects
2. Scientific Aspects
Pages 16-50
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From page 16... ...
It is a great advantage that a common set of techniques gene identification and cloning, for example are broadly applicable. Not only can we improve on past, traditional methods with the more precise modern methods, but we can explore new areas as well.
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From page 17... ...
The major differences between traditional breeding and molecular biological methods of gene transfer lie neither in goals nor processes, but rather in speed, precision, reliability, and scope. When traditional breeders cross two sexually reproducing plants or animals, tens of thousands of genes are mixed.
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From page 18... ...
Gene transfer techniques are key to many applications of biotechnology. The essence of genetic engineering is the ability to identify a particular gene one that encodes a desired trait in an organism isolate the gene, study its function and regulation, modify the gene, and reintroduce it into its natural host or another organism.
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From page 19... ...
Cloned genes also are used as diagnostic test probes in medicine and agriculture to detect specific diseases. Gene Transfer Technology To transfer genes from one organism to another, molecular biologists use vectors.
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From page 20... ...
Cell Culture and Regeneration Techniques The ability to regenerate plants from single cells is important for progress with gene transfer into plants. Animals cannot be regenerated asexually, so the only way to introduce a foreign gene into all cells of an animal is to insert it into the sperm, egg, or zygote.
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From page 21... ...
As biotechnology expands, it will be critical to understand why different species have differing abilities to regenerate from cell cultures into plants and how factors such as the genetic or physiological origin of the cells and the culture conditions affect growth. Most plant cells appear to be totipotent, that is, they are in a reversible differentiated state that will permit them to regenerate into a whole plant under appropriate conditions.
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From page 22... ...
By fusing two types of cells, antibody-producing B lymphocytes and quasi-immortal cancer cells from mice, scientists found that the resulting hybrid cells, called hybridomas, secreted large amounts of homogeneous antibodies. Each hybridoma has the ability to grow indefinitely in cell culture and thus can produce an almost unlimited supply of a specific "monoclonal" antibody.
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From page 23... ...
Both genetic engineering and monoclonal antibody technology, another major development in biotechnology, greatly increase the specificity and accuracy of analytical research methods. Further, these new technologies are permitting highly specific molecular analyses to be done and are opening new areas of inquiry.
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From page 24... ...
The following paragraphs highlight some examples of how genetic engineering can be used to enhance crop production. The Genetic Engineering of Plants Perhaps the most direct way to use biotechnology to improve crop agriculture is to genetically engineer plants that is, alter their basic genetic structure so they have new characteristics that improve the efficiency of crop production.
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From page 25... ...
Researchers have also transferred the gene into yeast cells. Early results show that the genetically engineered yeast do produce the sulfur-rich protein.
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From page 26... ...
One of the complicating factors that must be understood is how certain plants produce allelopathic molecules and at the same tune protect themselves against these chemicals. Observations of nature combined with abilities to engineer plants might also provide opportunities to manipulate plant growth and development.
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From page 27... ...
As our understanding grows, we will likely discover additional ways to regulate and control plant growth and development. For example, perhaps scientists can improve on ways to control fruit ripening, so ripening can be delayed until the fruit is en route to market.
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From page 28... ...
In laboratory tests the ice-minus strain has been sprayed on plants to displace the wild strain and thereby provide the crop with some measure of frost protection. Although the genetically engineered, ice-minus Pseudomonas is already several years old, field tests necessary to test its commercial application have been blocked by public apprehension that has led to court actions and confusion over the types of precautions needed to regulate such environmental testing.
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From page 29... ...
The most well-known bacteria able to fix nitrogen belong to the genus Rhizobium, which associates with members of the legume farniTy such as soybeans, beans, peas, peanuts, alfalfa, and clover. Genetic engineers would like to find ways to improve nitrogen fixation in these plants and extend the ability to others.
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From page 30... ...
Another approach involves trying to engineer plants to fix nitrogen themselves. Some progress has been maple in these approaches, due to extensive basic research on the genetics and biochemistry of nitrogen fixation.
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From page 31... ...
Hormones are often structurally complex and their production could require the concerted expression of a number of genes. Thus, extensive basic research on the biosynthetic pathways of these chemicals is necessary before they can be manufactured in microbial, cell culture, or plant systems.
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From page 32... ...
Baculoviruses are relatively stable in storage, during application, and in the field, and can be produced on a commercial scale. They have been modified with various foreign genes and have expressed those genes in insect cell cultures and silkworm larvae (see the Appendix for details)
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From page 33... ...
These new methods will give breeders unparalleled precision in manipulating desired traits, and at the same time, they will speed up the process. In the long-term, they may open the door to interspecies gene transfers.
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From page 34... ...
Molecular gene transfer into animal cells predates similar experimentation with plants. Unlike plants, however, animals cannot be regenerated asexually.
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From page 35... ...
is a naturally occurring hormone that increases milk production in cows. Scientists have been able to genetically engineer bacteria to produce the hormone, which when administered to lactating cows daily can increase milk production up to 40 percent.
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From page 36... ...
Introducing the booroola gene into other sheep and cattle could offer a fast, reliable way to increase the productivity of ewe and cow herds. Although the gene could be crossed into some breeds by sexual breeding, its introduction by molecular gene transfer would be faster and, more important, it would allow the trait to be passed to a wider range of livestock.
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From page 37... ...
Thus, one important use for biotechnology in animal agriculture will be in the diagnosis, prevention, and control of animal diseases. Monoclonal antibodies in particular offer great potential for helping scientists understand animal disease.
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From page 38... ...
Using the tools provided by biotechnology, researchers are working to develop vaccines for many important animal diseases. As mentioned earlier, therapeutic treatments against scours have been developed using monoclonal antibodies.
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From page 39... ...
The first commercial application of a genetically altered vaccine- anc] actually the first environmental release of an engineered product is Omnivac, a vaccine that immunizes swine against pseuclorabies.
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From page 40... ...
Animal agriculture will further benefit as scientists develop vaccines against other specific animal diseases. ALTERING INTESTINAL ORGANISMS A more speculative area of interest for genetic engineers lies inside agricultural animals.
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From page 41... ...
Once developed, such processes could prove more economical as well as less environmentally damaging than current industrial processes. Alternative Fuels Many people have hoped bioprocessing could have a significant impact on fuel production, but the present economic situation favors the extraction of natural reserves of petroleum, gas, and coal.
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From page 42... ...
When a diversity of biomass materials is used, problems are compounded by the design of fermentation apparatus and the selection of microorganisms adapted to grow on different feedstocks. Continued research on bioprocessing for bulk chemicals and alternative fuels, however, is important.
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From page 43... ...
Modern biotechnology looks to single-cell protein primarily as an animal feed, but some scientists consider human consumption a possibility, too. Other Products Bioprocessing already contributes to our ability to produce vitamins, amino acids, enzymes, and more recently hormones, and this role should increase in the future.
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From page 44... ...
As mentioned in previous examples, some bioprocessing systems can transform plant debris and other wastes into useful products, in effect creating an inexpensive and abundant renewable resource. Another current example is a new strain of yeast genetically engineered with an enzyme that converts the lactose in whey, a dairy industry waste product, into ethanol, which has fuel energy value.
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From page 45... ...
4. Cellular techniques developing and refining techniques for cell culture, cell fusion, regeneration of plants, and other manipulations of plant and animal cells and embryos.
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From page 46... ...
Although they are merely general cataTogs of a plant, animal, or microbial genome, chromosome maps are important guidelines for finding specific genes of importance to agriculture. Chromosome maps can show genetic engineers where to begin their search for specific genetic information.
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From page 47... ...
Although methods for cell culture, cell fusion, regeneration of plants from cells, and embryo manipulation exist for some species, these techniques must yet be successfully adapted to other species, which include important crops and livestock animals. Moreover, specific microorganisms such as yeasts, fungi, viruses, and bacteria important to agriculture and bioprocessing must be able to be cultured to allow both basic research and practical applications.
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From page 48... ...
ENVIRONMENTAL CONSIDERATIONS Many of the pending applications of biotechnology will require releasing genetically engineered plants, animals, and microbes into the environment. Clearly, the more that is known about the ecology and behavior of plants, animals, and microorganisms, the better are our chances of assessing the potential values and possible risks involved in introducing genetically altered versions into the field.
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From page 49... ...
IMPROVED TECHNIQUES AND APPLICATIONS The repertoire of molecular biology and cell culture techniques needed to implement advances in genetic engineering is incomplete. Methods for gene transfer in many plants, animals, and microbes; plant cell culture and regeneration; and animal embryo culture and manipulation are inadequate to support the goal of improving agricultural productivity.
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From page 50... ...
INCREASED ATTENTION TO THE ECOLOGICAL ASPECTS OF BIOTECHNOLOGY Both the public and private sectors should increase their efforts to develop an extensive body of knowledge of the ecological aspects of biotechnology in agriculture. In particular, studies must be done to further our understanding of the behavior and effects of genetically engineered organisms.
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