Gene-Edited Meat: Disentangling Consumers' Attitudes and Potential Purchase Behavior.

Novel gene-editing (GE) technologies provide promising opportunities to increase livestock productivity and to tackle several global livestock production sustainability and food security challenges. However, these technologies, as with previous genetic modification technologies in food production, are very likely to generate social controversy and opposition toward their use in the meat industry. Here, we explored public attitudes and consumption predisposition toward gene-edited meat products and their potential added benefits to livestock farming. Our results show that societal perception currently comes as a package, where the use of gene-editing technology acts as an extrinsic cue of meat products quality, and is used to make a range of inferences about all quality facets at once. Although consumers with anti-GE attitudinal positions generally were not sensitive to price discounts or added benefits, added benefits increased the consumption predisposition of most moderate and pro-GE consumers, where benefits related to animal welfare had larger effects than those relating to the environment or human health issues.

New insights and current tools for genetically engineered (GE) sheep and goats.

Genetically engineered sheep and goats represent useful models applied to proof of concepts, large-scale production of novel products or processes, and improvement of animal traits, which is of interest in biomedicine, biopharma, and livestock. This disruptive biotechnology arose in the 80s by injecting DNA fragments into the pronucleus of zygote-staged embryos. Pronuclear microinjection set the transgenic concept into people's mind but was characterized by inefficient and often frustrating results mostly because of uncontrolled and/or random integration and unpredictable transgene expression. Somatic cell nuclear transfer launched the second wave in the late 90s, solving several weaknesses of the previous technique by making feasible the transfer of a genetically modified and fully characterized cell into an enucleated oocyte, capable of cell reprogramming to generate genetically engineered animals. Important advances were also achieved during the 2000s with the arrival of new techniques like the lentivirus system, transposons, RNA interference, site-specific recombinases, and sperm-mediated transgenesis. We are now living the irruption of the third technological wave in which genome edition is possible by using endonucleases, particularly the CRISPR/Cas system. Sheep and goats were recently produced by CRISPR/Cas9, and for sure, cattle will be reported soon. We will see new genetically engineered farm animals produced by homologous recombination, multiple gene editing in one-step generation and conditional modifications, among other advancements. In the following decade, genome edition will continue expanding our technical possibilities, which will contribute to the advancement of science, the development of clinical or commercial applications, and the improvement of people's life quality around the world.

Large animal models of cardiovascular disease.

The human cardiovascular system is a complex arrangement of specialized structures with distinct functions. The molecular landscape, including the genome, transcriptome and proteome, is pivotal to the biological complexity of both normal and abnormal mammalian processes. Despite our advancing knowledge and understanding of cardiovascular disease (CVD) through the principal use of rodent models, this continues to be an increasing issue in today's world. For instance, as the ageing population increases, so does the incidence of heart valve dysfunction. This may be because of changes in molecular composition and structure of the extracellular matrix, or from the pathological process of vascular calcification in which bone-formation related factors cause ectopic mineralization. However, significant differences between mice and men exist in terms of cardiovascular anatomy, physiology and pathology. In contrast, large animal models can show considerably greater similarity to humans. Furthermore, precise and efficient genome editing techniques enable the generation of tailored models for translational research. These novel systems provide a huge potential for large animal models to investigate the regulatory factors and molecular pathways that contribute to CVD in vivo. In turn, this will help bridge the gap between basic science and clinical applications by facilitating the refinement of therapies for cardiovascular disease.

p21(Waf1/Cip1) as a molecular sensor for BoHV-4 replication.

BoHV-4 replication cycle is dependent on the S-phase of the cell-cycle at the stage of viral DNA synthesis. Because p21 is a rate-limiting regulator of the G1/S-phase transition and up-regulated by DNA-damaging agents, in this study p21 expression in BoHV-4 infected cells was investigated. The p21 promoter was found to be highly activated in a dose- and time-dependent manner following BoHV-4 infection only in cells which are permissive for BoHV-4 replication. Thus p21 expression reports on BoHV-4 replication and could represent a host cell defensive response to infection-associated cellular damage.

CMV enhancer-promoter is preferentially active in exocrine cells in vivo.

The CMV enhancer-promoter sequence is often used as a transcriptional regulatory element in vector systems. We have used this control element to drive expression of GFP in a lentivirus vector transgene in pigs and chickens. Promoted as a 'universal' enhancer/promoter element capable of transcriptional activity in a number of cells in vitro, CMV-GFP transgene expression in vivo is preferentially observed in exocrine cells. This expression profile validates the use of this transcriptional control sequence to target expression to exocrine cells in gene transfer strategies.

Production of transgenic farm animals by viral vector-mediated gene transfer.

Transgenic technology holds considerable promise to advance understanding in biomedical and agricultural systems with some believing that one day transgenic animals may directly contribute to farming and breeding practice. Nevertheless, applications in livestock have been restricted in part by the inefficiency of the technology. The recent development of lentivirus vectors for transgene delivery may overcome some of this limitation. This presentation describes these vectors, their advantages and limitations.

Dolly for dinner? Assessing commercial and regulatory trends in cloned livestock.

As cloning technologies become more widely established, will products enter the food chain sooner than regulatory agencies and the public might be prepared for?

Prolactin inhibits cell loss and decreases matrix metalloproteinase expression in the involuting mouse mammary gland but fails to prevent cell loss in the mammary glands of mice expressing IGFBP-5 as a mammary transgene.

Insulin-like growth factor-binding protein 5 (IGFBP-5) mediates involution of the mammary gland. The decrease in DNA content and mammary gland weight which accompanies involution was inhibited by prolactin (PRL) in wild-type but not transgenic mice expressing IGFBP-5. Phospho-STAT5 protein levels were significantly lower in IGFBP-5 transgenic mice during lactation suggesting that IGFBP-5 antagonises PRL signalling in the mammary epithelium. In contrast, phospho-STAT3 levels increased during involution to a similar extent in both wild-type and transgenic mice and were unaffected by PRL. PRL inhibited gene expression of matrix metalloproteinases (MMPs) 3 and 12 but not tissue plasminogen activator or plasmin in wild-type and transgenic animals. The effects of PRL on MMPs appear to be indirect since PRL failed to inhibit MMP-3, -7 or -12 expression in HC-11 cells or in a co-transfection including an activated PRL receptor, STAT5 and a MMP-3-luciferase reporter gene. PRL is a potent inhibitor, both of cell death, an effect which is suppressed by IGFBP-5, and of MMP expression, which is independent of the actions of IGFBP-5.

Disease-resistant genetically modified animals.

Infectious disease adversely affects livestock production and animal welfare, and has impacts upon both human health and public perception of livestock production. The authors argue that the combination of new methodology that enables the efficient production of genetically-modified (GM) animals with exciting new tools to alter gene activity makes the applications of transgenic animals for the benefit of animal (and human health) increasingly likely. This is illustrated through descriptions of specific examples. This technology is likely to have specific application where genetic variation does not exist in a given population or species and where novel genetic improvements can be engineered. These engineered animals would provide valuable models with which to investigate disease progression and evaluate this approach to controlling the disease. The authors propose that the use of GM animals will complement the more traditional tactics to combat disease, and will provide novel intervention strategies that are not possible through the established approaches.

Insulin-like growth factor binding proteins initiate cell death and extracellular matrix remodeling in the mammary gland.

We have demonstrated that insulin-like growth factor binding protein-5 (IGFBP-5) production by mammary epithelial cells increases dramatically during forced involution of the mammary gland in rats, mice and pigs. We proposed that growth hormone (GH) increases the survival factor IGF-I, whilst prolactin (PRL) enhances the effects of GH by decreasing the concentration of IGFBP-5, which would otherwise inhibit the actions of IGFs. To demonstrate a causal relationship between IGFBP-5 and cell death, we created transgenic mice expressing IGFBP-5, specifically, in the mammary gland. DNA content in the mammary glands of transgenic mice was decreased as early as day 10 of pregnancy. Mammary cell number and milk synthesis were both decreased by approximately 50% during the first 10 days of lactation. The concentrations of the pro-apoptotic molecule caspase-3 was increased in transgenic animals whilst the concentrations of two pro-survival molecules Bcl-2 and Bcl-x were both decreased. In order to examine whether IGFBP-5 acts by inhibiting the survival effect of IGF-I, we examined IGF receptor- and Akt-phoshorylation and showed that both were inhibited. These studies also indicated that the effects of IGFBP-5 could be mediated in part by IGF-independent effects involving potential interactions with components of the extracellular matrix involved in tissue remodeling, such as components of the plasminogen system, and the matrix metallo-proteinases (MMPs). Mammary development was normalised in transgenic mice by R3-IGF-I, an analogue of IGF-I which binds weakly to IGFBPs, although milk production was only partially restored. In contrast, treatment with prolactin was able to inhibit early involutionary processes in normal mice but was unable to prevent this in mice over-expressing IGFBP-5, although it was able to inhibit activation of MMPs. Thus, IGFBP-5 can simultaneously inhibit IGF action and activate the plasminogen system thereby coordinating cell death and tissue remodeling processes. The ability to separate these properties, using mutant IGFBPs, is currently under investigation.

On the use of post-transcriptional processing elements in transgenes.

RNA processing events modulate final productivity of a given transgene. We have evaluated a series of RNA elements for their ability to enhance alpha1-antitrypsin production in mammary cells. Our results indicate the need for a case-by-case assessment of each construct design and the occurrence of gene silencing events in vivo.