Animal Biotechnology Science-Based Concerns (2002) / Chapter Skim
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1. Introduction
1. Introduction
Pages 15-33
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From page 15... ...
For example, is it theoretically possible that a vector used for gene transfer could escape and become integrated into the DNA of another organism and thereby create a hazard? The second was whether the food and other products of animal biotechnology, whether genetically engineered or not, or from clones, are substantially different from those derived by more traditional, extant technologies.
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From page 16... ...
Genetically engineered poultry, swine, goats, cattle, and other livestock also are beginning to be used as generators of pharmaceutical and other products, potential sources for replacement organs for humans, and models for human disease. The technology to produce foreign proteins in milk by expressing novel genes in the mammary glands of livestock already has advanced beyond the experimental stage, with some of the products currently in clinical trials (Colman, 1996; Murray and Maga, 19994.
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From page 17... ...
Companies also are interested in farm animals as possible sources of replacement organs for humans. Transplantation is an accepted and successful treatment for organ failure, but there is an enormous shortage of available human organs.
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From page 18... ...
Neither BNT nor SNT result in an exact replica of an individual animal, although the progeny are very similar to each other and to their donor cell parent. Any genetic dissimilarity is likely due to the cytoplasmic inheritance of mitochondria from the donor egg, which possesses its own DNA, and to other cytoplasmic factors, which seem to have the potential to influence the subsequent "reprogramming" of the transferred somatic cell genome in such a way that spatial and temporal patterns of gene expression in the embryo are affected as it develops (Cummins, 2001; Jaenisch and Wilmut, 2001)
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From page 19... ...
BOX 1.2 Progression of Technologies Incorporated into Modern Animal Agricultures g Vaccinations and other health technologies2 Artificial inseminations Freezing of semen4 Sire testing and selections Use of antibiotics in feed to increase gains Embryo transfers Embryo splitting and cloning from blastomeres~ In vitro maturation/in vitro fertilization of oocytes and in vitro culture of resulting embryos Use~bD~lav~in~n~sandloi~e~nginf~ Hormonal sex reversal and production of monosex fish stocks Chromosome set manipulations Steroid administration to improve weight gain Bovine somatotropin (BST) to increase milk production in dairy cows Marker-assisted selection 'Technologies are presented in approximate sequential order of adoption; several technologies (such as artificial insemination, which was first described in 1910 but not widely adopted until the 1 950s)
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From page 20... ...
The modern Holstein, which dominates the contemporary United States dairy industry, little resembles its ancestors of only a half-century ago. Milk production per cow increased almost threefold between 1945 and 1995 (Majeskie, 1996)
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From page 21... ...
The growth and quality of such animals are also amenable to genetic engineering through modern biotechnology. Genetically engineered or highly selected aquatic species present special problems in terms of confinement, as the features that might make them attractive commercially might pose risks to the genetic base of their wild relatives with which they can interbreed (Hallerman and Kapuscinski, 1 992b)
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From page 22... ...
For these reasons, it is worthwhile discussing Box 1.2 and some of the issues that these technologies have raised before moving on to the ones associated with Box 1.3. CONCERNS REGARDING EXTANT TECHNOLOGIES Animal Health There are well-established guidelines for the application of technologies that maintain animal health, such as standard vaccination against viral and bacterial diseases.
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From page 23... ...
failed to find a definitive link between the agricultural use of antibiotics in animal feed drinking water and antibiotic resistance of human pathogens. The report states, "The use of drugs in the food production industry is not without some problems and concerns, but does not appear to constitute an immediate public health concern." Since that report was released, additional information, raising further concerns, has been released (Fey, 2000; Gorbach, 2001~.
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From page 24... ...
There also has been a remarkable recent loss of fertility, with successful pregnancies resulting from first insemination dropping from more than 40 percent to as low as 20 percent or less in some herds as milk yields have risen (Pryce et al., 2000; Royal et al., 2000~. Embryo recovery and transfer provides the opportunity for a particularly valuable animal to parent many more offspring in her lifetime than would be otherwise possible (Seidel, 1984~.
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From page 25... ...
A hormone treatment analogous to that used to produce a timed ovulation in the large farm animals is used to induce gonadal maturation in fish (Mittelmark and Kapuscinski, 2001~. None of these techniques have raised public health concerns, since the hormones are similar or identical to those in normal reproduction and the amounts used within the physiologic range.
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From page 26... ...
What distinguishes it from somatic cell nuclear transfer, the technology that led to the creation of Dolly and much of the controversy over human cloning, is the stage of development at which the nuclei are transferred (Wilmut et al., 1998~. In the older procedure, the cells or blastomeres used were from the so-called morula stage of cell development (although some were from the cleavage stage and others from the blastocyst stage)
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From page 27... ...
. Analogous, though possibly more serious, abnormalities might be associated with cloning from somatic cells and are discussed further in Chapters 2 and 6 of this report.
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From page 28... ...
The Monsanto product, Posilac™, now is widely used throughout the U.S. dairy industry, where milk production can be increased as much as 30 percent in well managed, appropriately fed herds, without adversely affecting the quality or composition of the milk.
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From page 29... ...
Such chromosome set manipulations have been applied to cultured marine mollusks to produce confined stocks of triploids that are unable to reproduce. This application is of particular importance, as some of the shellfishes most suited to aquaculture are not indigenous to a given area and can pose ecologic risks to native species should they or their larvae escape
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From page 30... ...
provide a tangible benefit to aquaculturists, and now make up almost half of commercial production in the Pacific Northwest. Unfortunately, repeatable induction of 100 percent triploidy on a commercial scale poses a considerable technical challenge.
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From page 31... ...
in reality is little different from nuclear transfer from somatic cells, listed in Box 1.3, except that the transferred nuclei might not have to be so extensively reprogrammed in the cytoplasm of the recipient oocyte. Similarly, chromosomal set manipulation remains partly experimental and partly an active commercial technology.
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From page 32... ...
, and animal welfare issues (Chapter 6) are all relevant and should be included in any considerations of wildlife and companion animal species.
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From page 33... ...
. Discussion of concerns regarding impacts of GE mice on the environment and human health also are limited in this report for several reasons.
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