Advances in Organ and Tissue Xenotransplantation

End-stage organ failure can result from various preexisting conditions and occurs in patients of all ages, and organ transplantation remains its only treatment. In recent years, extensive research has been done to explore the possibility of transplanting animal organs into humans, a process referred to as xenotransplantation. Due to their matching organ sizes and other anatomical and physiological similarities with humans, pigs are the preferred organ donor species. Organ rejection due to host immune response and possible interspecies infectious pathogen transmission have been the biggest hurdles to xenotransplantation's success. Use of genetically engineered pigs as tissue and organ donors for xenotransplantation has helped to address these hurdles. Although several preclinical trials have been conducted in nonhuman primates, some barriers still exist and demand further efforts. This review focuses on the recent advances and remaining challenges in organ and tissue xenotransplantation.

Outlook on genome editing application to cattle

In livestock industry, there is growing interest in methods to increase the production efficiency of livestock to address food shortages, given the increasing global population. With the advancements in gene engineering technology, it is a valuable tool and has been intensively utilized in research specifically focused on human disease. In historically, this technology has been used with livestock to create human disease models or to produce recombinant proteins from their byproducts. However, in recent years, utilizing gene editing technology, cattle with identified genes related to productivity can be edited, thereby enhancing productivity in response to climate change or specific disease instead of producing recombinant proteins. Furthermore, with the advancement in the efficiency of gene editing, it has become possible to edit multiple genes simultaneously. This cattle breed improvement has been achieved by discovering the genes through the comprehensive analysis of the entire genome of cattle. The cattle industry has been able to address gene bottlenecks that were previously impossible through conventional breeding systems. This review concludes that gene editing is necessary to expand the cattle industry, improving productivity in the future. Additionally, the enhancement of cattle through gene editing is expected to contribute to addressing environmental challenges associated with the cattle industry. Further research and development in gene editing, coupled with genomic analysis technologies, will significantly contribute to solving issues that conventional breeding systems have not been able to address.

Generating Cloned Goats by Somatic Cell Nuclear Transfer-Molecular Determinants and Application to Transgenics and Biomedicine

The domestic goat (Capra aegagrus hircus), a mammalian species with high genetic merit for production of milk and meat, can be a tremendously valuable tool for transgenic research. This research is focused on the production and multiplication of genetically engineered or genome-edited cloned specimens by applying somatic cell nuclear transfer (SCNT), which is a dynamically developing assisted reproductive technology (ART). The efficiency of generating the SCNT-derived embryos, conceptuses, and progeny in goats was found to be determined by a variety of factors controlling the biological, molecular, and epigenetic events. On the one hand, the pivotal objective of our paper was to demonstrate the progress and the state-of-the-art achievements related to the innovative and highly efficient solutions used for the creation of transgenic cloned does and bucks. On the other hand, this review seeks to highlight not only current goals and obstacles but also future challenges to be faced by the approaches applied to propagate genetically modified SCNT-derived goats for the purposes of pharmacology, biomedicine, nutritional biotechnology, the agri-food industry, and modern livestock breeding.

The contribution of transgenic and genome-edited animals to agricultural and industrial applications

For centuries, animal breeders have intentionally selected the parents of the next generation based on their concept of the 'ideal' animal. The dramatic differences seen in the appearance and productivity of different breeds show the power of such selection on DNA sequence variations. Unfortunately, the global furore over the use of modern biotechnologies to introduce desired genetic variations into animal breeding programmes, and the regulatory uncertainty associated with these recombinant DNA techniques, has effectively precluded the use of these technologies in food animal breeding programmes. Ironically, many of these early transgenic animal applications targeted traits that favoured sustainability, such as disease resistance and decreased environmental impact. As a consequence, transgenic animals have had little opportunity to affect global agriculture, and only a handful of pharmaceutical applications have been successfully commercialised. New developments in genome editing hold considerable promise for targeting traits that improve both animal health and welfare, and frequently involve no introduction of DNA sequences from other species. Nonetheless, future global regulation and public acceptance of such methods remain uncertain. Proposals to regulate genome-edited animals based solely on the process used to influence DNA sequence variations (i.e. intentional genome editing) and any potential attendant risks, with no counterbalancing consideration of the ensuing benefits or risks associated with conventional selection programmes, will potentially forestall the use of genome editing in animal breeding programmes. No activity can survive a risk-only evaluation, and there are considerable opportunity costs associated with preventing breeders' access to safe technologies in order to achieve genetic improvements in livestock populations.

Intracellular delivery of HA1 subunit antigen through attenuated Salmonella Gallinarum act as a bivalent vaccine against fowl typhoid and low pathogenic H5N3 virus

Introduction of novel inactivated oil-emulsion vaccines against different strains of prevailing and emerging low pathogenic avian influenza (LPAI) viruses is not an economically viable option for poultry. Engineering attenuated Salmonella Gallinarum (S. Gallinarum) vaccine delivering H5 LPAI antigens can be employed as a bivalent vaccine against fowl typhoid and LPAI viruses, while still offering economic viability and sero-surveillance capacity. In this study, we developed a JOL1814 bivalent vaccine candidate against LPAI virus infection and fowl typhoid by engineering the attenuated S. Gallinarum to deliver the globular head (HA1) domain of hemagglutinin protein from H5 LPAI virus through pMMP65 constitutive expression plasmid. The important feature of the developed JOL1814 was the delivery of the HA1 antigen to cytosol of peritoneal macrophages. Immunization of chickens with JOL1814 produced significant level of humoral, mucosal, cellular and IL-2, IL-4, IL-17 and IFN-γ cytokine immune response against H5 HA1 and S. Gallinarum antigens in the immunized chickens. Post-challenge, only the JOL1814 immunized chicken showed significantly faster clearance of H5N3 virus in oropharyngeal and cloacal swabs, and 90% survival rate against lethal challenge with a wild type S. Gallinarum. Furthermore, the JOL1814 immunized were differentiated from the H5N3 LPAI virus infected chickens by matrix (M2) gene-specific real-time PCR. In conclusion, the data from the present showed that the JOL1814 can be an effective bivalent vaccine candidate against H5N3 LPAI and fowl typhoid infection in poultry while still offering sero-surveillance property against H5 avian influenza virus.

Effects of melatonin on superovulation and transgenic embryo transplantation in small-tailed han sheep (Ovis aries)

OBJECTIVE

In this study, the effects of melatonin on superovulation and the transfer of transgenic embryos were investigated in Small-Tailed Han sheep.

DESIGN

Different doses of melatonin (0, 40 or 80 mg/animal) were subcutaneously implanted into both multiparous (4-5 years old) donors and recipients before superovulation and estrus synchronization. The one-year-old young ewes without melatonin treatment served to evaluate the reproductive efficiency of the adult multiparous ewes. Ewes with superovulation were used as embryo donors. The estrus were induced in embryo recipients after embryo transpimplanted.

RESULTS

The results showed that the number of corpora lutea of the ewes received subcutaneous 40 or 80 mg melatonin implant (13.4±1.05/ewe, 15.1±1.62/ewe) were significantly higher than that of in control group (8.8±0.37/ewe) (p<0.05). Similarily the number of recovered embryos from the ewes received subcutaneous 40 or 80 mg melatonin implant (10.3±0.84/ewe, 10.9±1.21/ewe) was significantly higher than the control group (6.2±0.60/ewe) (p<0.05). The transimplantd embryos from 40 or 80 mg melatonin treated donors dramatically improved the pregnancy and birth rates compared to control ewes. In addition, both 40 mg and 80 mg melatonin implatation lead to more lambs born per embryo.

CONCLUSIONS

These observations provide valuable information for the application of melatonin in increasing superovulation and transgenic embryo transplantation efficiency in sheep.

Production of transgenic bovine cloned embryos using piggybac transposition

Transgenic research on cattle embryos has been developed to date using viral or plasmid DNA delivery systems. In this study, a different gene delivery system, piggybac transposition, was employed to investigate if it can be applied for producing transgenic cattle embryos. Green or red fluorescent proteins (GFP or RFP) were transfected into donor fibroblasts, and then transfected donor cells were reprogrammed in enucleated oocytes through SCNT and developed into pre-implantation stage embryos. GFP was expressed in donor cells and in cloned embryos without any mosaicism. Induction of RFP expression was regulated by doxycycline treatment in donor fibroblasts and pre-implantational stage embryos. In conclusion, this study demonstrated that piggybac transposition could be a mean to deliver genes into bovine somatic cells or embryos for transgenic research.

Streptococcus iniae beta-hemolysin streptolysin S is a virulence factor in fish infection

Streptococcus iniae is a leading pathogen of intensive aquaculture operations worldwide, although understanding of virulence mechanisms of this pathogen in fish is lacking. S. iniae possesses a homolog of streptolysin S (SLS), a secreted, pore-forming cytotoxin that is a proven virulence factor in the human pathogen S. pyogenes. Here we used allelic exchange mutagenesis of the structural gene for the S. iniae SLS precursor (sagA) to examine the role of SLS in S. iniae pathogenicity using in vitro and in vivo models. The isogenic Delta sagA mutant was less cytotoxic to fish blood cells and cultured epithelial cells, but comparable to wild-type (WT) S. iniae in adherence/invasion of epithelial cell monolayers and resisting phagocytic killing by fish whole blood or macrophages. In a hybrid striped bass infection model, loss of SLS production led to marked virulence attenuation, as injection of the Delta sagA mutant at 1000x the WT lethal dose (LD80) produced only 10% mortality. The neutralization of SLS could represent a novel strategy for control of S. iniae infection in aquaculture.

Hermaphroditism in 3 chimeric mice

Hermaphroditism was diagnosed in three, 6-month-old, male, chimeric mice generated by microinjection of 129/Ola XY recombinant embryonic stem cells into unsexed C57BL/6 blastocysts. Grossly, mice Nos. 1 and 2 had perigenital masses and hydrometra. All mice had unilateral ovaries and cystic endometrial hyperplasia. Mice Nos. 1 and 3 also had contralateral testes and epididymides. Histologically, mice Nos. 1 and 3 were true hermaphrodites with unilateral ovotestes, while mouse No. 2 was a pseudohermaphrodite with ovarian tissue only. The presence of a uterus with cystic endometrial hyperplasia in these mice resembles XY pseudohermaphroditism in miniature schnauzers. The mice were determined to be 95 to 100% chimeric via haircoat color; however, the presence of both male and female sex organs in these phenotypically male mice suggests otherwise. Published reports note incidences for sex chimeras and hermaphroditism in genetically engineered mice of 50% and 20%, respectively. Hermaphroditism is expected to increase as the numbers of chimeric mice rise with technical advances in genetic engineering.

Animal transgenesis: state of the art and applications

There is a constant expectation for fast improvement of livestock production and human health care products. The advent of DNA recombinant technology and the possibility of gene transfer between organisms of distinct species, or even distinct phylogenic kingdoms, has opened a wide range of possibilities. Nowadays we can produce human insulin in bacteria or human coagulation factors in cattle milk. The recent advances in gene transfer, animal cloning, and assisted reproductive techniques have partly fulfilled the expectation in the field of livestock transgenesis. This paper reviews the recent advances and applications of transgenesis in livestock and their derivative products. At first, the state of art and the techniques that enhance the efficiency of livestock transgenesis are presented. The consequent reduction in the cost and time necessary to reach a final product has enabled the multiplication of transgenic prototypes around the world. We also analyze here some emerging applications of livestock transgenesis in the field of pharmacology, meat and dairy industry, xenotransplantation, and human disease modeling. Finally, some bioethical and commercial concerns raised by the transgenesis applications are discussed.

The impact of vaccines and the future of genetically modified poxvirus vaccines for poultry

The regular use of live or killed vaccines against infectious agents has remarkably improved the efficiency of poultry production. In some cases eradication of disease has been possible when the pathogen is antigenically stable and confined to a certain geographical area. In other instances monovalent or polyvalent live or killed vaccines have been effective in reducing mortality and morbidity. Many conventional vaccines are developed by trial and error and basic information about their genetic make-up is not known. While the poultry industry has benefited from the regular use of conventional vaccines, there is need for a new generation of effective vaccines that require minimal handling of birds during administration. Using molecular techniques, it is possible to identify the genes associated with virulence and protection. In genetically engineered vaccines, genes that encode protective antigens can be expressed in bacterial or viral vectors. In this regard, avianpox virus vectors appear to be promising for the generation of polyvalent vaccines expressing antigens from multiple pathogens.

Overview of new vaccines and technologies

Molecular technology has given us a greater insight into the aetiology of disease, the functioning of the immune system and the mode of action of veterinary pathogens. The knowledge gained has been used to develop new vaccines with specific, reactive antigens which elicit protective immune mediated responses (humoral and/or cell mediated) in the host. These vaccines should not burden the immune system by initiating responses against non-essential antigens. However, the efficacy of these vaccines is only as good as the delivery technology or route used to present them to the immune system. Some vaccines, traditionally given by the parenteral route, are now given by the natural route; either orally or intranasally. Two major advantages, often interrelated, are the rapid onset of immunity and stimulation of the local, mucosal immunity. These new technologies are now making an impact on current vaccine development. The balance has to be found between what is technologically feasible and what will provide at least as good a protective immunity as current, conventional vaccines. As new and emerging diseases appear globally, new opportunities arise for molecular and conventional technologies to be applied to both the development and delivery of novel vaccines, as well as the improvement of vaccines in current use.

Construction of a virulent, green fluorescent protein-tagged Yersinia ruckeri and detection in trout tissues after intraperitoneal and immersion challenge

A green fluorescent protein (GFP) expressing strain of Yersinia ruckeri was created by the transposition of a Tn10-GFP-kan cassette into the genome of Y. ruckeri Strain YRNC10. The derivative, YRNC10-gfp, was highly GFP fluorescent, retained the gfp-km marker in the absence of kanamycin selection, and exhibited in vitro growth kinetics similar to those of the wild type strain. YRNC10-gfp colonized and caused mortality in immersion and intraperitoneally challenged rainbow trout Oncorhynchus mykiss, although it was modestly attenuated compared to the wild type strain. The distribution and location of YRNC10-gfp in infected fish was visualized by epifluorescence microscopy. Abundant extracellular bacteria and a small number of intracellular bacteria were observed in the kidney, spleen and peripheral blood. To determine the percentage of trout cells containing intracellular bacteria, GFP fluorescence was measured by flow cytometry. A small population of GFP positive leukocytes was detected in peripheral blood (1.6%), spleen (1.1%) and anterior kidney (0.4%) tissues. In summary, this is the first report of the construction of a virulent, GFP-tagged Y. ruckeri, which may be a useful model for detecting and imaging the interactions between an aquatic pathogen and the natural salmonid host.

Tick, fly, and mosquito control—Lessons from the past, solutions for the future

In order to continue to produce livestock in a sustainable fashion, it is suggested that what was used in the past will continue to form the mainstay of future control. For the foreseeable future, we must conserve what we have, and use it in combination with all the principles of integrated pest management, namely strategic and focussed treatments of animals, environmental control of breeding sites, disease management (including the principles of enzootic stability), and resistant breeds. Whilst new technologies, such as the development of vaccines both against the insect pest in some cases or the disease they transmit in others, and genetic engineering hold out some hope for the future; these are not sufficiently well advanced to permit wholesale application.

The immune response to equine arteritis virus: potential lessons for other arteriviruses

The members of the family Arteriviridae, genus Arterivirus, include equine arteritis virus (EAV), porcine reproductive and respiratory syndrome virus (PRRSV), lactate dehydrogenase-elevating virus (LDV) of mice, and simian hemorrhagic fever virus (SHFV). PRRSV is the newest member of the family (first isolated in North America and Europe in the early 1990s), whereas the other three viruses were recognized earlier (EAV in 1953, LDV in 1960, and SHFV in 1964). Although arterivirus infections are strictly species-specific, the causative agents share many biological and molecular properties, including their virion morphology, replication strategy, unique properties of their structural proteins, and their ability to establish distinctive persistent infections in their natural hosts. The arteriviruses are each antigenically distinct and cause different disease syndromes in their natural hosts. Similarly, the mechanism(s) responsible for the prolonged and/or persistent infections that characterize infections with each arterivirus in their natural hosts are remarkably different. The objective of this review is to compare and contrast the immune response to EAV with that to the other three arteriviruses, and emphasize the potential relevance of apparent similarities and differences in the neutralization characteristics of each virus.

Biomedical and Agricultural Applications of Animal Transgenesis

Additive transgenesis by pronuclear injection of the mouse zygote has been in use for more than 20 yr and gene targeting in mouse embryonic stem cells for almost as long. Together, these techniques have revolutionized animal biology by helping to unravel much of what we now know about gene function. Both additive transgenics and targeting can also be performed in livestock species but the impact has not yet been substantial. In part, this has been the result of the inefficiency of the techniques but-at least in agriculture-also to a lack of obvious practicality. This review assesses the extent to which this situation is changing, with particular reference to applications in biopharming, xenotransplantation, and large animal models.

Engineering immunity in the mammary gland

The major physiological function of milk is the transport of amino acids, carbohydrates, lipids, and minerals to mammalian offspring. However, milk is also a rich collection of antimicrobial substances, which provide protection against pathogenic infections. These molecules safeguard the integrity of the lactating mammary gland, but also provide protection for the suckling offspring during a time when its immune system is still immature. The protective substances can be classified into two categories: 1) nonspecific defense substances, which provide innate immunity, and 2) molecules such as antibodies, which provide adaptive immunity and are directed against specific pathogens. The antimicrobial potency of milk has not been a target for farm animal breeding in the past, and present day ruminants provide suboptimal levels of antimicrobial substances in milk. Altered breeding regimes, pharmacological intervention, and transgenesis can be utilized to improve the antimicrobial properties of milk. Such alterations of milk composition have implications for human and animal health.

[Can gene technology in agriculture prevent hunger in the world?]

The world population grows rapidly: the number of mouths to feed increases. Is an agriculture without gene technology able to produce sufficiently in order to prevent hunger? Research indicates that hunger is not the result of short comings in agricultural outputs. It is however the result of poverty. This problem will not be solved by gene technology based agricultural production. This article explains the basic principles of mainstream and organic farming. Literature shows that the production potentials of both kinds of farming are, by far most, not yet exhausted. Gene technology is therefore unnecessary.

[Modern biotechnology: a new box for Pandora?]

In a bird's-eye view attention has been paid to a number of items of biotechnology. Amongst others to the beginning of the recombinant DNA technology or genetic modification. Mentioned are the bull Herman, the American tomato 'Flavr Savr' and the sheep Dolly. And further something about the supporters and the opponents of genetic modification and the safety of it. The why of transgenic plants and animals. The legislation and the Netherlands as possible transgene-production country.

[Genetic modification of animals]

Genetic modificated animals are an essential part of modern biotechnology since the years of the seventies of last century. In the past selective crossbreeding of plants and animals took place in order to obtain the desired characteristics but nowadays this is done with the aid of biotechnology i.e. through transgenese, knock-out animals and cloning. A number of fields of application of genetic modification of animals are listed. In order to limit the risks that genetic modificated animals may carry with them the necessary legislation is formulated. A number of risks and the main rules are mentioned.

Recent progress and problems in animal cloning

It is remarkable that mammalian somatic cell nuclei can form whole individuals if they are transferred to enucleated oocytes. Advancements in nuclear transfer technology can now be applied for genetic improvement and increase of farm animals, rescue of endangered species, and assisted reproduction and tissue engineering in humans. Since July 1998, more than 200 calves have been produced by nuclear transfer of somatic cell nuclei in Japan, but half of them were stillborn or died within several months of parturition. Morphologic abnormalities have also been observed in cloned calves and embryonic stem cell-derived mice. In this review, we discuss the present situation and problems with animal cloning and the possibility for its application to human medicine.

[DNA: what does it do, and what do we do with it?]

We present a bird's-eye view of the fundamentals and applications of the DNA technology. DNA is the carrier of genetic information. Separate pieces of DNA can be isolated in two different ways: cloning or via the polymerase chain reaction. Analysis of DNA has already found several applications in medical diagnosis and criminal investigations. Modification of DNA from lower organisms in order to produce proteins is now generally accepted. Genetic modification of plants and animals is promising, but is also the subject to a public and political debate. Gene therapy is a promise of the future. Analysis as well as modification of DNA has ethical consequences and both require an effective legislation.

Transgenesis may affect farm animal welfare: a case for systematic risk assessment

This paper considers (potentially) harmful consequences of transgenesis for farm animal welfare and examines the strategy of studying health and welfare of transgenic farm animals. Evidence is discussed showing that treatments imposed in the context of farm animal transgenesis are by no means biologically neutral and may compromise animal health and welfare. Factors posing a risk for the welfare of transgenic farm animals include integration of a transgene within an endogenous gene with possible loss of host gene function (insertional mutations), inappropriate transgene expression and exposure of the host to biologically active transgene-derived proteins, and in vitro reproductive technologies employed in the process of generating transgenic farm animals that may result in an increased incidence of difficult parturition and fetal and neonatal losses and the development of unusually large or otherwise abnormal offspring (large offspring syndrome). Critical components of a scheme for evaluating welfare of transgenic farm animals are identified, related to specific characteristics of transgenic animals and to factors that may interact with the effects of transgenesis. The feasibility of an evaluation of welfare of transgenic farm animals in practice is addressed against the background of the objectives and conditions of three successive stages in a long-term transgenic program. Concrete steps with regard to breeding and testing of transgenic farm animals are presented, considering three technologies to generate transgenic founders: microinjection, electroporation and nuclear transfer, and gene targeting including gene knockout. The proposed steps allow for unbiased estimations of the essential treatment effects, including hemi- and homozygous transgene effects as well as effects of in vitro reproductive technologies. It is suggested that the implementation of appropriate breeding and testing procedures should be accompanied by the use of a comprehensive welfare protocol, specifying which parameters to monitor, at which stages of the life of a farm animal, and in how many animals. Some prerequisites and ideas for such a protocol are given. It is anticipated that systematic research into the welfare of farm animals involved in transgenesis will facilitate the use of the safest experimental protocols as well as the selection and propagation of the healthiest animals and, thereby, enable technological progress that could be ethically justified.

Pregnancy and live birth from nonsurgical transfer of in vivo- and in vitro-produced blastocysts in the rhesus monkey

Embryo transfer in the rhesus monkey has been historically limited to transfer of cleavage stage embryos. In order to allow genetic manipulation of rhesus embryos in vitro, without using invasive surgical techniques, it is important to explore the transfer of morula and blastocyst stage embryos. Embryos were produced by in vitro fertilization from gonadotropin-stimulated monkeys, or were obtained by nonsurgical uterine flushing of naturally mated or artificially inseminated females. Nonsurgical transfer was accomplished by inserting a metal guide through the cervix into the uterus, after which a hollow cell sampler was inserted over the guide. The guide was removed and a catheter was inserted containing one to five embryos. Several pregnancies resulted from in vitro- and in vivo-derived blastocysts, and two pregnancies were carried to term resulting in one live birth. Blood samples were collected regularly to monitor plasma levels of chorionic gonadotropin, luteinizing hormone, and progesterone. The recipients received progesterone as a subcutaneous implant or daily injections from the day of transfer. The approach described in this study provides the opportunity to explore transgenic and chimeric models in the monkey by the development of noninvasive methods to transfer late-stage embryos that have been manipulated in vitro.

Towards the routine application of nucleic acid technology for avian disease diagnosis

The use of nucleic acid technology (polymerase chain reaction, probing, restriction fragment analysis and nucleotide sequencing) in the study of avian diseases has largely been confined to fundamental analysis and retrospective studies. More recently these approaches have been applied to diagnosis and what one might call real-time epidemiological studies on chickens and turkeys. At the heart of these approaches is the identification and characterisation of pathogens based on their genetic material, RNA or DNA. Among the objectives has been the detection of pathogens quickly combined with the simultaneous identification of serotype, subtype or genotype. Nucleic acid sequencing also gives a degree of characterisation unmatched by other approaches. In this paper we describe the use of nucleic acid technology for the diagnosis and epidemiology of infectious bronchitis virus, turkey rhinotracheitis virus (avian pneumovirus) and Newcastle disease virus.

Bad ethics, good ethics and the genetic engineering of animals in agriculture

Genetic engineers have been remiss in addressing ethical and social issues emerging from this powerful new technology, a technology whose, implications for agriculture are profound. As a consequence of this failure, society has been uneasy about genetic engineering of animals and has had difficulty distinguishing between genuine and spurious ethical issues the technology occasions. Many of the most prominent concerns do not require a serious response. On the other hand, concerns about a variety of possible risks arising from genetic engineering of animals require careful consideration and dialogue with the public. Such concerns are an admixture of ethics and prudence. A purely ethical challenge, however, hitherto not addressed, is represented by problems of animal welfare that arise out of genetically engineering agricultural animals. A principle of "conservation of welfare" is suggested as a plausible moral rule to guide such genetic engineering.

[Ethics and new technological applications in animals]

Cloning and genetic engineering of animals are in the picture of public debate. The intrinsic value is an important issue in the ethical debate about both new technologies. The intrinsic value is introduced during the seventies as counterpart of the instrumental use of animals. The introduction of two new aspects, 'the ability to function independently' and 'naturalness', gives more insight in the meaning of intrinsic value. In two cases the consequences of the recognition of intrinsic value is discussed. The author concludes that cloning and genetic engineering are an infringement of the intrinsic value. The ethical debate about the transgenic bull Herman is the first experience in practice.

The genetic engineering of production traits in domestic animals

The transfer of recombinant DNA by microinjection of embryo pronuclei provides a novel approach to the manipulation of production traits in domestic animals. In this review, several of the key areas currently under investigation are examined and their progress evaluated. These include the manipulation of the endocrine system by altered growth hormone genes and the modification of animal biochemistry by the introduction of the cysteine biosynthetic pathway and the glyoxylate cycle. The possibilities inherent in the alteration of structural proteins important to domestic animal productivity, and some ethical issues relevant to the release of modified animals are also considered. The experimental information obtained so far in the area indicates that transcriptional regulation of the genes and a thorough understanding of the physiological processes involved are both important factors in the practical application of the technique to the improvement of animal productivity.

[Biotechnology in perspective]

Biotechnology is a collective term for a large number of manipulations of biological material. Fields of importance in stock-keeping include: (1) manipulation of reproductive processes; (2) genetic manipulation of macro-(farm) animals and micro-organisms and (3) manipulation of metabolism. Fitting in biotechnological findings in breeding-stock farming has repercussions in several fields such as the relationship between producers and the ancillary and processing industries, service industries, consumers and society as a whole. The use of biotechnical findings will also require further automation and adaptation of farm management. Biotechnology opens up a new area and new prospects for farm animal husbandry. These can only be regarded as positive when they take a permanent development of the entire section into account.

[Genetic manipulation in farm animals: how and why?]

A review of the history of the knowledge of the development of DNA was presented on the symposium 'Biotechnology'. Entirely in agreement with expectations, genetic manipulation became suitable for use, also in farm animals, approximately thirty years after the discovery of the double helix. The technology available for transfection is limited and is only successful in a small number of cases: less than one per cent. In addition, gene constructions give rise to a large number of problems as they are not tissue-specific and fail to function at the correct time in the course of development. The knowledge of interesting genes (at DNA level) in farm animals is of vital importance. Detecting these genes will undoubtedly still require considerable effort. In view of the technical state of things, medical and physiological studies using transfection will obviously have to provide a new insight prior to use. This is in agreement with the memorandum on 'Ethics and Biotechnology in Animals'. A 'no, unless' procedure is recommended in this note, room being left for 'good' objectives of research following ethical consideration.

[Animal welfare aspects of biotechnology]

It's difficult to value the effects on animals caused by genetic engineering. Nowadays an enormous increase on animal tests is taken place. The detrimental alterations of small number of living born gene altered animals are in literature explained by deficiencies in method and the increased growth is described with deficient mechanisms on regulation. Not only the intention to increase productivity by genetic engineering but also the method to improve by fragments (genes) not facing the animals totality is against prevention of cruelty to animals.

Use and control of biotechnological methods

The use of molecular virology is described. Emphasis is placed on molecular biology, especially methods involving gene technology. The respective techniques allow characterisation of viruses by molecular cloning and nucleotide sequencing as well as the development of new diagnostic tools and vaccines. Genetically engineered live viruses serve as examples to study potential risks of vaccines derived from such viruses.