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fruits of the poisoned tree



The article below shows that there is a great deal of pressure to commercialized the meat of cloned animals. This strange commercial pressure seems to be exerted even though it is clear that cloning leads to extensive abnormal transcription activity in the cloned animals. Presently the vast majority of clones do not survive so the meat from cloned animals may be a special case of "road kill". Seriously , the off springs of cloned animals should be considered "fruits of the poisoned tree" and treated with considerable care and scrutiny. The proponents seem to press for "substantial equivalence" concept as providing adequate safeguards but further work is needed to insure that the off springs of cloned sires do not bear many subtle genetic or epigenetic instabilities leading to dangerous products.
http://www.isb.vt.edu/news/2002/news02.nov.html#nov0201
WILL FOOD PRODUCTS FROM CLONED ANIMALS BE COMMERCIALIZED SOON?
Eric M. Hallerman

The development of somatic cell nuclear transfer (SCNT) cloning offers significant benefits for genetic improvement of production herds, but poses concerns regarding food safety and animal welfare.1 The US Food and Drug Administration (FDA) contacted companies developing SCNT clones for agricultural use and requested that food products from cloned animals or their progeny not be entered into the human or animal food supply until evaluation of these issues is completed.2 Against this background, the FDA and the Pew Initiative on Food and Biotechnology hosted a public workshop, "Animal Cloning and the Production of Food Products: Perspectives from the Food Chain,"3 in Dallas, Texas on September 26, 2002. The workshop was a forum for 150 participants from industry, academia, non-governmental organizations, and the public to hear presentations on key issues and to provide input to FDA as it develops its policy on foods from cloned animals.

SCNT cloning. Somatic cell nuclear cloning involves transferring the nucleus from a differentiated cell of a donor animal, frequently an adult, into an enucleated egg. The introduced nucleus is reprogrammed by the cytoplasm of the egg and directs the development of a new embryo, which is transferred to a recipient female to develop to term. The offspring formed will be identical to the donor in terms of nuclear DNA, but will differ in initial patterns of methylation of nuclear genes and in mitochondrial genes. Spatial and temporal patterns of gene expression in cloned embryos differ from those in non-cloned embryos.4 After cloning of sheep was reported in 1997, SCNT was applied to many species, including cattle, goats, pigs, mice, and, more recently, rabbits and cats. At present, production of SCNT clones is inefficient, with less than one percent of the nuclear transfers resulting in a live, cloned offspring. Even with low efficiency, there are many potential applications for reproducing highly desired genotypes, including rare or endangered species, pets, elite sires or dams, breeds with desirable production traits but low fertility, or transgenic animals that have high value, for which rapid propagation is desirable. The success rate is increasing with refinement of SCNT protocols.

Highlights of the workshop. One key technical issue is whether the composition of food products from cloned animals is the same as that from non-cloned animals. Erik Forsberg of Infigen (Deforest, WI) presented results of a study comparing the composition of milk from 10 cloned and six control cows with values published in the scientific literature. Milk composition was quantified at laboratories at the University of Wisconsin and Utah State University where researchers did not know which samples pertained to clones. Concentrations of solids, fat, protein, lactose, caseins, lactalbumin, and most minerals, and somatic cell counts did not differ significantly between cloned and non-cloned groups. Significant differences in certain fatty acids and minerals were attributed to differences in feeds consumed by the two groups. The results are reported in detail in a manuscript submitted to a peer-reviewed journal.

Ron Gillespie (Cyagra, Worcester, MA) and Don Coover (SEK Genetics, Galesburg, KS) placed cloning of animals within an agricultural perspective. At a price of $19,000, commercial producers are not the ones who are buying cloned calves—rather the consumers of this technology are selective breeding programs that are marketing genetically improved germplasm. Producers of selectively bred cattle are interested in better utilizing the genetics of high performance females; cloning of selected females will allow more matings with high performance sires, providing more opportunities to produce fine candidate sires to improve future production. Should the price decline dramatically, dairy producers may become interested in cloning in order to produce only female cattle. For beef cattle, it takes so much time to identify an outstanding sire that his productive life is limited; cloning offers the possibility of extending the availability of his genes. Producers of selectively bred pigs are interested in cloning because porcine semen does not cryopreserve well, and supplies of semen from boars in high demand are limited. Gillespie concluded that cloning will benefit producers and consumers when the price is right. Coover mentioned that small producers are concerned that they will prove less able to benefit from cloning than large producers.

A number of workshop speakers presented data showing high rates of perinatal mortality or clinical signs of distress in neonatal cloned animals. It is difficult to determine whether such problems are due to cloning by nuclear transfer, to embryo culture or transfer, or to some combination of cloning, culture, and transfer methods. Workshop attendees representing the Humane Society of America, Animal Welfare Institute, and United Poultry Concerns expressed concern that impacts of cloning would exacerbate animal welfare problems imposed by conventional production of animals in confinement facilities.

Carol Tucker Foreman (Food Policy Institute, Consumer Federation of America, Washington, DC) said that a hasty decision to approve clones as food carries "incendiary potential for public debate."5 Poor public acceptance of cloned animals may limit commercial application of the technology.

Regulatory prospects. John Matheson (FDA) discussed FDA actions anticipated over the next year. A detailed assessment of food safety data on SCNT clones and offspring will be prepared. An assessment will consider animal safety issues for clones and progeny, as well as genetic diversity impacts of cloning on populations of cattle and hogs. Release of both white papers is targeted for January 1, 2003. A proposed policy and guidance document considering risk management, legal, and enforcement issues will be published during spring 2003. At that time, comments on the proposed policies will be invited. Depending on the level of interest and the nature of comments, a public meeting may be held in spring or summer 2003, possibly before the Veterinary Medicine Advisory Committee. A "final" guidance policy will be published, accompanied by monitoring for compliance. The guidance policy will be revised as needed.

Combining numbers presented by the various speakers, on the order of 100-200 SCNT cloned animals have been produced and transferred to farms in the United States. Any role they might play in agricultural production will be determined within the next year.
Sources

1. National Research Council. 2002. Animal biotechnology: Science-based concerns. http://www.nap.edu/books/0309084393/html.

2. Center For Veterinary Medicine, US Food and Drug Administration. 2001. Update on livestock cloning. CVM Update, July 13, 2001. http://www.fda.gov/cvm/index/updates/clones.html.

3. Pew Initiative on Food and Biotechnology. 2002. Animal Cloning and the Production of Food Products - Perspectives from the Food Chain. http://pewagbiotech.org/events/0924/sept26.php.

4. Humpherys DK, et al. 2002. Abnormal gene expression in cloned mice derived from embryonic stem cell and cumulus cell nuclei. Proceedings of the National Academy of Sciences USA 99: 12889-12894. http://www.pnas.org/cgi/reprint/192433399v1.pdf.

5. Gillis J. 2002. Cloned cows' milk normal, data show: Finding could speed commercial use. Washington Post, Friday, September 27, 2002, page E3. http://www.washingtonpost.com (go to archives).

Eric M. Hallerman
Department of Fisheries and Wildlife Sciences
Virginia Tech
ehallerm@vt.edu

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