Biotechnology An Industry Comes of Age (1986) / Chapter Skim
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Biotechnology in Agriculture
Biotechnology in Agriculture
Pages 30-42
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From page 30... ...
Biotechnology will also yield drugs, feed additives, and growth enhancers that have never before been available in commercial quantities. A particularly intriguing example is growth hormone, which may result in faster growing, larger, and leaner animals and which has increased milk production in dairy cattle by up to 40 percent.
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From page 31... ...
, equine infectious anemia, bovine leukosis virus, and a number of viral diseases that strike dogs and cats. Monoclonal antibodies can also fend off disease by conferring passive immunity to an infectious agent.
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From page 32... ...
Researchers are trying to genetically engineer Rhizobium bacteria so that they will fix nitrogen more efficiently or infect other crops in addition to legumes. An important consideration in this work is the competitiveness of the genetically engineered bacteria.
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From page 33... ...
A particularly interesting example involves the bacterium Pseudomonas syringae. A protein on the surface of this widespread bacterium initiates the formation of ice when temperatures drop below freezing.
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From page 34... ...
In recent decades, plant and animal breeders have developed sophisticated techniques to transfer traits among organisms that can interbreed. They have also developed a host of supporting technologies, such as cell and tissue culture, embryo transfer, and artificial insemination, that facilitate these basic genetic manipulations.
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From page 35... ...
"It supplied us with a natural, soilborne organism called Agrobacterium tumefaciens. This soilborne organism invades plant tissues through wound sites and introduces genetic information, by a mechanism unknown as yet, into the chromosome of the plant cell.
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From page 36... ...
This bacterium contains a large tumorinducing plasmid that can insert part of its DNA into the DNA of whatever plant cell the bacterium infects. If researchers replace the tumor-inducing genes of the plasmid with foreign DNA, the bacterium can be used as a vector to introduce novel DNA into plant cells.
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From page 37... ...
We did not find this pea small-subunit gene being expressed, for example, in the roots and stems of the plant, but only in the leaves." Another group of proteins that have been a focus of work by plant molecular biologists are the storage proteins in plant seeds. The seeds of legumes and cereal grains provide humans with an estimated 70 percent of their dietary protein requirements, but some of the most important storage proteins in these seeds are deficient in certain essential amino acids that must be made up in other ways.
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From page 38... ...
For instance, researchers at Monsanto are trying to isolate the gene that codes for the enzyme EPSP synthase, which enables plants to resist an herbicide known as glyphosate that is sold by Monsanto under the trade name Roundup. By growing plant cells in the presence of increasing levels of the herbicide, the researchers were able to isolate a strain with a greatly amplified expression of the gene.
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From page 39... ...
"We just don't have enough knowledge yet to understand how to regulate at will, and in a controlled fashion, the expression of a gene." The research needed to acquire this knowledge requires both greater cooperation between plant molecular biologists and traditional plant breeders and a commitment by the federal government to fund this kind of interdisciplinary effort, according to Jaworski. "There is a lot of basic research that has to be done in parallel with the applied research if we are going to be successful in moving the technology from the laboratory into the field." The Genetic Engineering of Animals Unlike plants, an animal cannot be regenerated asexually from cells plucked at random from certain parts of its body.
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From page 40... ...
Swine are already bred for maximal growth, and it is not clear whether insertion of a growth hormone gene would further increase their size. Also, the mice transformed by the growth hormone gene showed signs of abnormally proportioned growth, and the female mice genetically engineered in this way were often sterile.
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From page 41... ...
drawing too many conclusions of what the value of this technique will be for general use." As in the genetic engineering of plants, an even more fundamental problem involves the regulation of the genes inserted into animal cells. The expression of an inserted gene can be influenced both by the regulatory sequences associated with the gene and by where the gene is inserted into the DNA of its host.
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From page 42... ...
in a way in which the outcome of that experiment is absolutely predictable. It is not yet possible to correctly or predictably alter the amino acid composition of the major corn protein by introducing amino acids that are essential for human and animal nutrition, or to predict if that protein will be expressed in normal, or perhaps larger, amounts.
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