Transgenic Animals

Regulatory policy for transgenic live- stock is being developed concurrently with several rap- idly advancing technologies for creating such animals. Adequacy of ethical, welfare, physiological, and envi- ronmental criteria applied to the selection of transgenes will have substantial implications for acceptance. Con- current evolution of regulatory policy and oversight will determine whether the existing collaboration of animal drug, veterinary biologic, environmental, and food safety agencies is appropriate. Industry infrastructure

Alpha-1-acid glycoprotein (AGP) or orosomucoid (ORM) is a 41-43-kDa glycoprotein with a pI of 2.8-3.8. The peptide moiety is a single chain of 183 amino acids (human) or 187 amino acids (rat) with two and one disulfide bridges in humans and rats,respectively. The carbohydrate content represents 45% of the molecular weight attached in the form of five to six highly sialylated complex-type-N-linked glycans. AGP is one of the major acute phase proteins in humans, rats, mice and other species. As most acute phase proteins, its serum concentration increases in response to systemic tissue injury, inflammation or infection, and these changes in serum protein concentrations have been correlated with increases in hepatic synthesis. Expression of the AGP gene is controlled by a combination of the major regulatory mediators, i.e. glucocorticoids and a cytokine network involving mainly interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF alpha), interleukin-6 and IL-6 related cytokines. It is now well established that the acute phase response may take place in extra-hepatic cell types, and may be regulated by inflammatory mediators as observed in hepatocytes. The biological function of AGP remains unknown; however,a number of activities of possible physiological significance, such as various immunomodulating effects, have been described. AGP also has the ability to bind and to carry numerous basic and neutral lipophilic drugs from endogenous (steroid hormones) and exogenous origin; one to seven binding sites have been described. AGP can also bind acidic drugs such as phenobarbital. The immunomodulatory as well as the binding activities of AGP have been shown to be mostly dependent on carbohydrate composition. Finally, the use of AGP transgenic animals enabled to address in vivo, functionality of responsive elements and tissue specificity, as well as the effects of drugs that bind to AGP and will be an useful tool to determine the physiological role of AGP.

Animal biotechnology is one of the main areas of biotechnology which concerns the application of animals, including transgenic animals, in various fields. Even though these transgenic animals can be useful for improving the welfare of humans and animals, the well-being of animals being used in the studies may be negatively affected. Ethical issues relating to experimentation on animals and the production of transgenic animals are discussed in this review, and included here is a consideration of the phenomena of "conditional ethical blindness". Finding alternative protocols including the 4 Rs (reduction, refinement, replacement, and responsibility) to minimize the employment of animals in scientific procedures is one way to solve these problematic issues. These strategies can be successively utilized for certain animal biotechnological protocols and can be used to intelligently avoid unethical manipulation of animals.

In the present scenario with the advancement of animal genetics to utilize the non-additive gene action two technologies i.e. molecular genetics technologies and reproductive assisted technologies have been developed to overcome the human requirement in short period of time genetically. The molecular genetics technologies that are adopted to exploit non-additive gene action are marker assisted selection technology, genetic markers, animal cloning and transgenic animals while that of reproductive assisted technologies are artificial insemination, embryo transfer, in-vitro fertilization, somatic cell nuclear transfer and multiple ovulation and embryo transfer. Modernized animal breeding technologies has being harnessed in various aspects of the livestock industry to hasten breed development for improved animal health and welfare, enhanced reproduction, and improved nutritional quality and safety of animal derived foods. Although substantial additional genetic gains can be achieved with selection on linked genetic markers, the ultimate aim will be to directly identify the main genes involved in a trait and to elucidate the function of each of these genes. To bring a genetic gain, it is well accepted that local animals must be safeguarded to maintain its purity, records must be kept to evaluate best animal and highly productive cows should not be crossbred with exotic breeds and breeding policy should be set. The genetic improvement for increased milk and meat output is inevitable. Such development interventions should operate within crossbreeding policy framework without affecting genetic diversity. INTRODUCTION With the advancement of biotechnology and molecular biology, Drinkwater and Hetzel, [1] revealed that meat and milk from farmed animals including livestock i.e. cattle, goat and buffalo along with meat and egg from poultry [2,3] are important sources of high quality protein and essential amino acids, minerals, fats and fatty acids, readily available vitamins, small quantities of carbohydrates and other bioactive components. The Food and Agriculture Organization (FAO) 2009 [4] estimated that meat consumption has grown with increase in population. The average global per capita meat consumption is 42.1 kg/year with 82.9 kg/year in developed and 31.1 kg/year in developing countries in a recommended daily animal sourced protein per capita of 50 kg per year. Milk on the other hand is consumed in various forms: liquid, cheese, powder, and cream at a global per capita consumption of 108 kg per person per year which is way below the FAO, 2011 [5] recommended daily consumption of 200 kg. Some poor countries may not be able to sustain these levels of meat and milk requirement, leading to malnutrition. Demand for meat and milk production is also expected to double in 2050 in developing countries, where population is expected to double. Thus, increasing production and the safe processing and marketing of meat and milk, and their products are big challenges for livestock producers. Biotechnology is being harnessed in various aspects of the livestock industry [6] to hasten breed development for improved animal health and welfare, enhanced reproduction, and improved nutritional quality and safety of animal derived foods.

The tools of recombinant protein expression are now being used to provide recombinant sources of both collagen and gelatin. The primary focus of this review is to discuss alternatives to bovine collagen for biomedical applications. Several recombinant systems have been developed for production of human sequence collagens. Mammalian and insect cells were initially used, but were thought to be too costly for commercial production. Yeast have been engineered to express high levels of type I homotrimer and heterotrimer and type II and type III collagen. Co-expression of collagen genes and cDNAs encoding the subunits of prolyl hydroxylase has lead to the synthesis of completely hydroxylated, thermostable collagens. Human types I and III collagen homotrimers have been expressed in transgenic tobacco plants, while transgenic mice have been engineered to produce full-length type I procollagen homotrimer as well as a α2 (I) homotrimeric mini-collagen. Most recently, a transgenic silkworm system was used to produce a fusion protein containing a collagenous sequence. Each of these transgenic systems holds great promise for the cost-effective large-scale production of recombinant human collagens. As seen in other recombinant expression systems, transgenic silkworms, tobacco, and mice lack sufficient endogenous prolyl hydroxylase activity to produce fully hydroxylated collagen. In mice and tobacco, this was overcome by over-expression of prolyl hydroxylase, analogous to what has been done in yeast and insect cell culture. In addition to recombinant alternatives to bovine collagen, other sources such as fish and sponge collagen are discussed briefly. Recombinant gelatin has been expressed in Pichia pastoris and Hansenula polymorpha in both non-hydroxylated and hydroxylated forms. Pichia was shown to be a highly productive system for gelatin production. The recombinant gelatins produced in yeast are of defined molecular weight and physio-chemical properties and represent a new biomaterial not previously available from animal sources. Genetic engineering has made great progress in the areas of recombinant collagen and gelatin expression, and there are now several alternatives to bovine material that offer an enhanced safety profile, greater reproducibility and quality, and the ability of these materials to be tailored to enhance product performance.

As part of a larger literature study on transgenic animals in mutagenicity testing, test results from the transgenic mutagenicity assays (lacI model; commercially available as the Big Blue(R) mouse, and the lacZ model; commercially available as the Mutatrade markMouse), were compared with the results on the same substances in the more traditional mouse bone marrow micronucleus test. 39 substances were found which had been tested in the micronucleus assay and in the above transgenic mouse systems. Although, the transgenic animal mutation assay is not directly comparable with the micronucleus test, because different genetic endpoints are examined: chromosome aberration versus gene mutation, the results for the majority of substances were in agreement. Both test systems, the transgenic mouse assay and the mouse bone marrow micronucleus test, have advantages and they complement each other. However, the transgenic animal assay has some distinct advantages over the micronucleus test: it i...

This review describes production and effects of reactive oxygen species (ROS) on airway function. ROS are important in many physiological processes but can also have detrimental effects on airway cells and tissues when produced in high quantities or during the absence of sufficient amounts of anti-oxidants. Therefore, these mediators play a prominent role in the pathogenesis of various inflammatory airway disorders, including asthma. Effects of ROS on airway function in asthma have been studied with isolated airway cells and tissues and with animal models and patients. With the use of inhibitors, transgenic animals and measurements of the release of ROS within the airways, it became clear that oxidative stress contributes to the initiation and worsening of inflammatory respiratory disorders.

Missense mutations in two related genes, termed presenilin 1 (PS1) and presenilin 2 (PS2), cause dementia in a subset of early-onset familial Alzheimer's disease (FAD) pedigrees. In a variety of experimental in vitro and in vivo settings, FAD-linked presenilin variants influence the processing of the amyloid precursor protein (APP), leading to elevated levels of the highly fibrillogenic Aβ1–42 peptides that are preferentially deposited in the brains of Alzheimer Disease (AD) patients. In this report, we demonstrate that transgenic animals that coexpress an FAD-linked human PS1 variant (A246E) and a chimeric mouse/human APP harboring mutations linked to Swedish FAD kindreds (APP swe) develop numerous amyloid deposits much earlier than age-matched mice expressing APP swe and wild-type Hu PS1 or APP swe alone. These results provide evidence for the view that one pathogenic mechanism by which FAD-linked mutant PS1 causes AD is to accelerate the rate of β-amyloid deposition in brain.

The development of the One World, One Health agenda coincides in time with the appearance of a different model for the management of human-animal relations: the genetic manipulation of animal species in order to curtail their ability as carriers of human pathogens. In this paper we examine two examples of this emergent transgenic approach to disease control: the development of transgenic chickens incapable of shedding avian flu viruses, and the creation of transgenic mosquitoes refractory to dengue or malaria infection. Our analysis elaborates three distinctions between the One World, One Health agenda and its transgenic counterpoint. The first concerns the conceptualization of outbreaks and the forms of surveillance that support disease control efforts. The second addresses the nature of the interspecies interface, and the relative role of humans and animals in preventing pathogen transmission. The third axis of comparison considers the proprietary dimensions of transgenic animals and their implications for the assumed public health ethos of One Health programs. We argue that the fundamental difference between these two approaches to infectious disease control can be summarized as one between strategies of containment and strategies of competition. While One World, One Health programs seek to establish an equilibrium in the human-animal interface in order to contain the circulation of pathogens across species, transgenic strategies deliberately trigger a new ecological dynamic by introducing novel animal varieties designed to out-compete pathogen-carrying hosts and vectors. In other words, while One World, One Health policies focus on introducing measures of inter-species containment, transgenic approaches derive their prophylactic benefit from provoking new cycles of intra-species competition between GM animals and their wild-type counterparts. The coexistence of these divergent health protection strategies, we suggest, helps to elucidate enduring tensions and concerns about how humans should relate to, appraise, and intervene on animals and their habitats.

Biotechnology applied to livestock encompasses various reproductive techniques supported by molecular biology. Technologies for the transfer of gene constructs involve microinjection into the pronucleus of fertilized oocytes or DNA mass transfer. The last one can be made through the use of sperm, which carry the incorporated gene construct into the ovum at fertilization, or through the use of retroviral vectors in cell lines. One of the prerequisites to establishing transgenic lines is the presence of the foreign DNA in the gametes or one-cell embryos to ensure that the conceptus develops into a transgenic animal. To reach this objective, foreign genes can be transferred using different methods and strategies depending up on the species of domestic animal used for this venture and their biological potential. Transgenic animals are now commonly used worldwide as models for human disease and the commercial availability of transgenic protein products for therapeutic use is thought to b...

Animal welfare can be assessed in a precise way using measures of several kinds of abnormal behaviour, aversion, physiological responses including adrenal and opioid activity, immunosuppression, opioid activity, disease incidence, weight gain, reproductive success and life expectancy. Welfare may be affected in various ways in transgenic animals and animals treated with biotechnology products. In order to assess this, carefully controlled studies using a wide range of welfare indicators are needed. These should be carried out for at least the total farm life of a breeding animal and for at least two generations. No such comprehensive studies of either category of animals have been reported in the scientific literature to date although some measures of the effects of bovine somatrophin have been made and are described. Neither the use of recombinant DNA products nor the keeping of transgenic animals should be permitted on commercial farms until it is clear that the welfare of these animals is not adversely affected in comparison with that of animals which do not have the products administered to them or which are not produced by transgenic procedures.

Genetic manipulation of a series of diverged arthropods is a highly desirable goal for a better understanding of developmental and evolutionary processes. A major obstacle so far has been the difficulty in obtaining marker genes that allow easy and reliable identification of transgenic animals. Here, we present a versatile vector set for germline transformation based on the promiscuous transposons mariner, Hermes and piggyBac. Into these vectors, we introduced a potentially universal marker system that is comprised of an artificial promoter containing three Pax-6 homodimer binding sites. This promoter drives strong expression of spectral variants of the enhanced green fluorescent protein (EGFP) in larval, pupal, and adult photoreceptors. Using special filter sets, the yellow (EYFP) and cyan (ECFP) variant are fully distinguishable and therefore represent a separable pair of markers. Furthermore, we adapted a simple plasmid-based transposition assay system to enable quick functional tests of our vectors in different arthropod species before employing them in more laborious germline transformation experiments. Using this system we demonstrate that our vectors transpose in both Drosophila melanogaster and Drosophila virilis.

Emerging evidence shows that ErbB2 signaling has a critical role in cardiomyocyte physiology, based mainly on findings that blocking ErbB2 for cancer therapy is toxic to cardiac cells. However, consequences of high levels of ErbB2 activity in the heart have not been previously explored. We investigated consequences of cardiac-restricted over-expression of ErbB2 in two novel lines of transgenic mice. Both lines develop striking concentric cardiac hypertrophy, without heart failure or decreased life span. ErbB2 transgenic mice display electrocardiographic characteristics similar to those found in patients with Hypertrophic Cardiomyopathy, with susceptibility to adrenergic-induced arrhythmias. The hypertrophic hearts, which are 2-3 times larger than those of control littermates, express increased atrial natriuretic peptide and β-myosin heavy chain mRNA, consistent with a hypertrophic phenotype. Cardiomyocytes in these hearts are significantly larger than wild type cardiomyocytes, with ...