A brief overview of biotechnology with an emphasis on livestock is presented. The authors discuss NDSU’s new undergraduate biotechnology program. A goal of this program was the development of better transfer methods of a biological gene into an already growing (or even adult animal) which would allow for the 'designing' of animals with specific traits which would be best suited to a particular, given situation. Gene mapping, cloning, the development of recombinant hormones and the development of subunit vaccines and diagnostics are other areas cited as needing more research

Redmer, D.A.

Reynolds, L.P.

A brief overview of biotechnology with an emphasis on livestock is presented. The authors discuss NDSU?s new undergraduate biotechnology program. A goal of this program was the development of better transfer methods of a biological gene into an already growing (or even adult animal) which would allow for the 'designing' of animals with specific traits which would be best suited to a particular, given situation. Gene mapping, cloning, the development of recombinant hormones and the development of subunit vaccines and diagnostics are other areas cited as needing more research

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Animal Biotechnology Lawrence P. Reynolds and Dale A. Redmer According to Webster's dictionary , biotechonology is , simply , "applied biological science" (Webster'~ , ~986). However, a more accurate definition of the emergmg fie ld of biotechnology would probably be similar to that given for NDSU's recently established undergraduate biotechnology program : "Biotechnology is an interdisciplinary field based on a combination of biology and technology ." (NDSU Bulle­tin , 1990-92). It is appropriate , therefore , that biotechnol­ogy and related research are becoming a major thrust at many state agricultural experiment stations , which have em­phasized applied research aimed at improving efficiency of agricultural production since their inception in the late 1800s (Kerr , 1987) . Examples of techniques currently being used in biotech­nology research include cloning of specific genes, transfer of genes between or within species, and culture of cell~ a~d embryos. These technique have been successfully apphed m several instances . For example , in the late 1970s, the human gene for insulin was succesfully transferred into bac­teria , which then produced large quantities of the hormone (Watson et aI., 1983). Because of its purity and ease of pro­duction , this "recombinant" insulin has become the standard insu lin used to treat diabetes in humans (Gilman et aI. , 1985) . Another example of the potential of applied biotechnol­ogy is gene therapy. In gene therapy , a genetic disease caused by a defective gene producing a defective enzyme or hormone would be treated by transferring the correct gene into a patient's own cells, which then would provid.e the cor­rect enzyme or hormone (Culliton , 1989; Fnedmann , 1989). This approach to treatment of genetic diseases has recently been approved for clinical evaluation on a Iim~ted basis (Culliton, 1990). In addition to medical uses, apphca­tion of biotechnology to agriculture was almost immediately recognized as having tremendous potential for economic benefit (Watson et aI. , 1983) . For instance, one can en­vision transfer of disease-resistance or growth-promoting genes into crop plants or farm animals. Recognizin~ this potentia l, in 1985 Congress specified that a major P?rtIon of the funds in the U.S. Department of Agriculture s Com­petitive Grants Program would be used to support agricul­tural biotechnology research (Kerr, 1987) . Reynolds and Redmer are associate professors, Department of A nimal and Range Sciences ; Redmer also is director of the Cell Biology Center of the NDSU Biotechnology Institute . 3 SPECIFIC EXAMPLES Because of its potential for enhanCing both the rate and efficiency of growth, transfer of the gene for growth hor­mone has been Widely studied . The first successful transfer of a growth hormone gene into a mammalian embryo was reported by Palmiter and coworkers (1982 , 1983). In these studies, early mouse embryos were injected with either the rat or human gene for growth hormone . Mice that were born with these genes , termed "transgenics ," grew at four times the rate of normal mice during their maximal growth phase. Encouraged by this success in mice, researchers sub­sequently have transferred human or bovine growth ho~­mone genes into early embryos to produce transgenic sheep, cattle and pigs (Hammer et aI. , 1985, 1986; Pursel et aI. , 1989; Roschlau et aI., 1989). These experiments have met with some success , especial­ly in pigs . In pigs , transfer of the bovine growth hormone gene resulted , in some cases , in improvements in daily weight gain and feed efficiency for two successive genera­tions (Pursel et aI., 1989). These studies , however, also have had several drawbacks . For instance , the percentage of attempted gene transfers that have been successful in large domestic animals has ranged from 0 .1 to 6.9 percent (Hammer et aI., 1986; Pursel et aI. , 1989; Roschlau et a I. , 1986). In other words , for every 1,000 embryos injected with the gene, only 1 to 69 offspring which actually carried the new gene would be born . In addition, the beneficial effects of gene transfer may be offset by serious side effects. For example, even thou~h ~igs with the bovine growth hormone gene grew faster With Im­proved feed efficiency, they also showed increased inci­dence of arthritis, cardiac disease, dermatitis, gastric ulcers, renal disease and reprod uctive failure (Pursel et aI., 1989). Thus, better understanding of regulation of gene expres­sion , improved methods for gene transfer and perhaps even modified methods of husbandry will be required before the benefits of gene transfer will be realized in production of transgenic farm animals. To date , the most successful method for gene transfer in large domestic animals has been microinjection of the gene directly into early embryos (Pursel et aI., 1989; Roschlau et aI., 1989; Sirard, 1989). Because of the need for large numbers of embryos , which must be manipulated in vitro (in a petri dish) and then successfully transferred to recipie~t animals , gene transfer has prOVided impetus for advances m technology of egg manipulation and embryo transfer. For example , it is now possible to stimulate growth of many ovarian follicles at the same time in a given cow , obtain the oocyte (egg) from each of these follicles either before or after ovulation , and fertilize these oocytes in vitro, to produce many embryos which are synchronized at a specific stage of Table 1. Superinduction of follicular development in cows. 8 development (Greve et a I. , 1989; Sirard 1989). These tech ­niques not only are useful for gene transfer but also are beginning to be applied in embryo transfer programs, with the goal of obtaining many offspring from outstanding dams. Development of these techniques is a good example of how the efforts of many dedicated researchers over many years will eventually benefit animal agriculture. Another example of applied animal biotechnology comes from NDSU's laboratories. Induction of superovulation by using gonadotropic hormones is the most widely used tech­nique for obtaining multiple eggs or embryos from cows (Lerner et at., 1986; Hasler et at., 1987). The usefulness of this technique, however, is limited by the variability of the superovulatory response among cows (Hasler et at., 1983, Lerner et aI., 1986; Saumande et at., 1985). That is, during a given hormone treatment, some cows may respond well, whereas other cows do not respond at all. This lack of response in some cows has been estimated to cost the em­bryo transfer industry millions of dollars annually in the U.S. alone. Recently, NDSU researchers have developed a treat­ment regimen wherein all cows tested to date have respon­ded well to treatment in terms of superinduction of follicular development, number of ovulations and number of em­bryos obtained (Tables 1 and 2). Because of the cost of superovulation regimens, this technique, which provides a means of obtaining a consistent superovulatory response in all cows, may be of tremendous value for use in gene trans­fer and embryo transfer programs . Development of this technique was only possible because a base of information built from many years of work by numerous investigators was available. PROSPECTS FOR THE FUTURE Better methods for transfer of genes into embryos have been developed for rodents and are beginning to be devel­oped for domestic animals (Pursel et at., 1989; Cherfas, 1990). These improved methods not only are more efficient but also result in expression of the gene only by appropriate tissue or organs, which should minimize the side effects and also improve the ability to regulate function of these genes. In addition to transfer of genes into embryos, the techniques described for gene therapy could be used not only to treat genetic diseases but also to transfer beneficial genes, such as growth-promoting or disease-resistance genes, into young or even adult animals. These techniques have already been used to transfer "marker" genes into adult dogs and pigs (Wilson et at., 1989; N abel et aI., 1989). The ability to transfer a beneficial gene into a growing or adult animal would allow for "designing" animals with spe­cific traits suited to a given situation. Another gene transfer approach is targetting genes to the mammary glands so that the resulting transgenic animals would secrete a specific product in their milk. This approach already has been used successfully to obtain human proteins in milk from sheep (Cherfas, 1990). As with any gene transfer technology, these methodologies will not be practical until much more is learned about regulation of gene expression as well as hus­bandry of transgenic animals. In addition, we must always consider not only the potential benefits but also the conse­quences of gene transfer, since application of these tech­niques will greatly accelerate the rate at which characteristics of animals can be manipulated. To do so without much thought and careful· investigation would be unwise and counterproductive. An area closely related to gene transfer is gene mapping. Although quantitative geneticists and animal breeders have Follicular size classesb COW 6 - <10 >10c 06W7 12 11 896 17 7 14T1 9 5 06W1 19 20 437 15 11 454 6 6 02P1 14 5 42S1 9 14 02W7 10 19 09W1 3 9 12R1 2 3 453 11 9 342 12 8 22T1 3 8 05W1 10 6 09U7 2 9 Mean ± SE 9.8 ± 1.3 9.4 ± 1.2 aRedmer, Kirsch and Reynolds (unpublished, 1990). Cows used In this study were mixed beef breeds, including Hereford, Angus, Simmental, Shorthorn and crossbreds. bSurface diameter (mm) of follicles for both ovaries from each cow. Ovaries were obtained at slaughter during the superovulatory treatment regimen. c Most cows exhibit only one follicle greater than 10 mm at a time. Table 2. Induction of superovulatory response in cows.8 Laparotomy/Surgery Data Day after No. of Cow estrusb ovulationsc 24x1 7 31 117 8 19 M15 7 19 M6 7 20 28x1 7 23 H10 7 25 W12 7 34 P9 10 23 32 7 26 BT27 8 22 37 8 19 Mean ± SE 7.4 ± 0.3 23.7 ± 1.5 aRedmer, Kirsch and Reynolds (unpublished, 1990). All cows used in this study were Angus. bDay on which laparotomy/surgery was performed after cows exhibi ted estrus (day 0) in response to superovulatory treatment regimen. c Number of ovulations was determined by counting the number of corpora lutea at laparotomy/surgery. been mapping genes at a relatively slow pace for many years, techniques termed restriction fragment length poly­morphisms and in situ hybridization have greatly accelerated the rate at which specific genes can be mapped to specific chromosomes. Excitement over application of these techni­ques led to an international conference entitled "Mapping 4 Domestic Animal Genomes," which was held at the Univer­sity of Illinois in April of this year. Mapping of genes will allow researchers to learn much about specific fu nctions of genes, relationships among genes and specific traits, regula­tion of gene expression and causes of genetic diseases. In addition, mapping of domestic animal genomes will make more genes available for gene transfer. Mapping of all of the ge nes of domestic species could feasibly be accomplished within the next few decades. Many other areas within animal biotechnology are ad­vancing rapidly, such as cloning of embryos, development of recombinant hormones, and development of subunit vac­cines and diagnostics. These techniques, developed through biotechnology, also are tremendously powerful tools for use in further research. Since the time between basic research discoveries and their practical application is shortening rapidly (National Academy of Sciences, 1989; Cherfas, 1990) , it is important to continue support for the state agricultural experiment stations in their efforts in bio­technology . In fact, increased support for basic and applied agricultural research has been cited as being critical if the U.S. is to remain competitive in the world market (Holt, 1987; Reynolds, 1987; Redmer et al., 1988) . It is likely that biotechnology and related research will play an ever increas­ing role in maintaining the economic vitality of animal agri­culture in the fu ture . LITERATURE CITED Culliton , B.J. 1989. Designing cells to deliver drugs. Science 246 : 746-751. Culliton , B.J . 1990. Gene therapy: Into the home stretch. Science 249:974-976 . Cherfas, J . 1990. Molecular biology lies down with the lamb . Science 249: 124-1 26. Friedmann , T. 1989 . Progress toward human gene therapy. Science 244 : 1275-1280. Gilman , A. G. , L.S . Goodman, T.W. Rail, and F. Murad (Eds.). 1985 . The Pharmacological Basis of Therapeutics, 7th edn., pg 1501. Macmillan, N.Y. Greve, T., H . Callesen, and P . Hytell . 1989. Follicular correlates with in-vitro fertilization in cattle . In : Cell Biology of Mammalian Egg Manipulation (T. Greve , P . Hytell and B.J . Weir , Eds.) J . Reprod . Fertil. Suppl. 38, pp 117-126. Hammer, R.E ., V.G . Pursel, e.E. Rexroad, Jr. , R.J . Wall , D.J. Bolt, K.M. Ebert, R.D. Palmiter, and R.L. Brinster. 1985. Pro­duction of transgenic rabbits, sheep and pigs by microinjection. Nature 315:680-685 . Hammer, R.E ., V.G . Pursel , e.E. Rexroad, Jr. , R.J . Wall, D.J. Bolt, R. D. Palmiter , and R.L. Brinster. 1986. Genetic engi­neering of mammalian embryos . J . Anim . Sci. 63 :269-278. Hasler, J .R. , A.D. McCauley, E.e. Schermerhorn, and R.H . Foote . 1983. Superovulatory responses of Holstein cows. Ther­iogenology 19:83-99. Hasler , J.F., A.D . McCauley, W.F. Lanthrop, and R.H. Foote. 1987 . Effect of donor-embryo-recipient interactions on preg­nancy rate in a large scale bovine embryo transfer program. Theriogenology 27: 139-168. Holt , D. 1987. A competitive R&D strategy for U.S. agriculture. Science 237 :1401-1402. Kerr , N.A. 1987. The Legacy. A Centennial History of the State Agricultural Experiment Stations 1887-1987. Missouri Agric . Exp. Sta . , Columbia , MO. Lerner, S.P., W.V. Thayne , R.D. Baker, T. Henschen, S . Mere ­dith , E. K. Inskeep, R.A. Dailey, P .E. Lewis, and R. L. Butcher. 1986. Age, dose of FSH and other factors affecting superovula­tion in Holstein cows. J . Anim . Sci. 63:176-183 . Nabel, E.G. , G . Plautz , F.M. Boyce, J .e. Stanley, and G .J . Nabel. 1989. Recombinant gene expression in vivo within endothelial cells of the arterial wall . Science 244:1342-1344. National Academy of Sciences . 1989. On Being a Scientist. Na­tional Academy Press , Washington , D.C. NDSU Bulletin 1990-92 . Vol. 80, No.2, pg 82. North Dakota State University of Agriculture and Applied Science , Fargo. Palmiter, R. D. , R .L. Brinster, R.E. Hammer, M.E. Trumbauer, M.G. Rosenfeld, N.C. Birnberg, and R.M . Evans . 1982 . Dra­matic growth of mice that develop from eggs micro injected with metallothionein-growth hormone fusion genes. Nature 300:611. Palmiter, R.D., G . Norstedt , R.E. Gelinas, R.E. Hammer , and R.L. Brinster. 1983. Metallothionein-human GH fusion genes stimulate growth of mice . Science 222:809-814. Pursel, V.G., e.A. Pinkert, K.F. Miller, D.J . Bolt , R.G . Campbell, R.D. Palmiter , R.L. Brinster, and R. E. Hammer. 1989. Genetic engineering of livestock. Science 244: 1281-1288. Redmer, D.A., L.P . Reynolds, and J.E. Tilton . 1988. Biotechnol­ogy and reproductive physio logy at NDSU. NO Farm Res . 46(3} :20-26. Reynolds, L.P . 1987 . Letters to the Editor: Agricultural R&D. Science 238:1494. Roschlau , K. , P . Rommel , L. Andreewa, M. Zackel, D. Roschlau , B. Zackel , M. Schwerin , R. Huhn , and K.G . Gazarjan . 1989. Gene transfer experiments in cattle . In : Cell Biology of Mam­malian Egg Manipulation (T. Greve, P. Hytell and B.J . Weir, Eds .) J . Reprod. Ferli1. Suppl. 38, pp 153-160. Saumande , J .D. Tamboura, and D. Chupin . 1985. Changes in milk and plasma concentrations of progesterone in cows after treatment to induce superovulation and their relationships with number of ovulations and of embryos collected. Theriogenology 23:719-731. Sirard , M.A. 1989. Practical aspects of in-vitro fertilization in cattle . In : Cell Biology of Mammalian Egg Manipulation (T . Greve, P . Hytell and B.J . Weir , Eds.) J . Reprod . Fertil. Suppl. 38, pp 127-134. Watson , J .D., J. Tooze, and D.T. Kurtz. 1983 . Recombinant DNA. A Short Course. W.H. Freeman, N.Y. Webster's . 1986. Third New International Dictionary of the English Language , Unabridged. Merriam-Webster, Springfield, MA. Wilson, J .M., L.K. Birinyi, R.N . Salomon, P . Libby, A. D. Callow, and R. e. Mulligan. 1989. Implantation of vascular grafts lined with genetically modified endothelial cells. Science 244: 1344­1346. 5 

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