Genetically Engineered Hamster Models of Dyslipidemia and Atherosclerosis

Animal models of human diseases play an extremely important role in biomedical research. Among them, mice are widely used animal models for translational research, especially because of ease of generation of genetically engineered mice. However, because of the great differences in biology between mice and humans, translation of findings to humans remains a major issue. Therefore, the exploration of models with biological and metabolic characteristics closer to those of humans has never stopped.Although pig and nonhuman primates are biologically similar to humans, their genetic engineering is technically difficult, the cost of breeding is high, and the experimental time is long. As a result, the application of these species as model animals, especially genetically engineered model animals, in biomedical research is greatly limited.In terms of lipid metabolism and cardiovascular diseases, hamsters have several characteristics different from rats and mice, but similar to those in humans. The hamster is therefore an ideal animal model for studying lipid metabolism and cardiovascular disease because of its small size and short reproduction period. However, the phenomenon of zygote division, which was unexpectedly blocked during the manipulation of hamster embryos for some unknown reasons, had plagued researchers for decades and no genetically engineered hamsters have therefore been generated as animal models of human diseases for a long time. After solving the problem of in vitro development of hamster zygotes, we successfully prepared enhanced green fluorescent protein (eGFP) transgenic hamsters by microinjection of lentiviral vectors into the zona pellucida space of zygotes. On this basis, we started the development of cardiovascular disease models using the hamster embryo culture system combined with the novel genome editing technique of clustered regularly interspaced short palindromic repeats (CRISPR )/CRISPR associated protein 9 (Cas9). In this chapter, we will introduce some of the genetically engineered hamster models with dyslipidemia and the corresponding characteristics of these models. We hope that the genetically engineered hamster models can be further recognized and complement other genetically engineered animal models such as mice, rats, and rabbits. This will lead to new avenues and pathways for the study of lipid metabolism and its related diseases.

In-situ monitoring of xenobiotics using genetically engineered whole-cell-based microbial biosensors: recent advances and outlook

Industrialisation, directly or indirectly, exposes humans to various xenobiotics. The increased magnitude of chemical pesticides and toxic heavy metals in the environment, as well as their intrusion into the food chain, seriously threatens human health. Therefore, the surveillance of xenobiotics is crucial for social safety and security. Online investigation by traditional methods is not sufficient for the detection and identification of such compounds because of the high costs and their complexity. Advancement in the field of genetic engineering provides a potential opportunity to use genetically modified microorganisms. In this regard, whole-cell-based microbial biosensors (WCBMB) represent an essential tool that couples genetically engineered organisms with an operator/promoter derived from a heavy metal-resistant operon combined with a regulatory protein in the gene circuit. The plasmid controls the expression of the reporter gene, such as gfp, luc, lux and lacZ, to an inducible gene promoter and has been widely applied to assay toxicity and bioavailability. This review summarises the recent trends in the development and application of microbial biosensors and the use of mobile genes for biomedical and environmental safety concerns.

Development and Significance of Mouse Models in Lymphoma Research

PURPOSE OF REVIEW

Animal models have played an indispensable role in interpreting cancer gene functions, pathogenesis of disease, and in the development of innovative therapeutic approaches targeting aberrant biological pathways in human cancers.

RECENT FINDINGS

These models have guided the therapeutic targeting of cancer-causing mutations and paved the way for assessing anti-cancer drug responses and the preclinical development of immunotherapies. The mammalian models of cancer utilize genetically edited or transplanted mice that develop fairly accurate disease histopathology. The mouse model also allows us to study the effect of tumor microenvironment in the development of lymphoma. The emergence of patient-derived xenografts provides a better opportunity for recapitulating primary lymphoma characteristics and researching personalized drug therapy. In conclusion, the refinement and advancement of available mouse models in lymphoma significantly minimize the therapeutic translational failures in patients.

Current risk assessment approaches for environmental and food and feed safety assessment

Foundational activities at the international level underlie current risk and safety assessment approaches for genetically engineered/modified organisms (GEOs/GMOs). Early risk assessment considerations beginning with the OECD 'Blue Book' established risk/safety assessment as the characterization of the organism and its environmental release; establishment and persistence in the environment; and human and ecological effects, analyzed in principle through existing methods. Important in this context was recognition that GEOs/GMOs as a class did not represent new risks relative to products of traditional plant breeding and that any incremental risk would need to be established on a stepwise case-by-case comparative basis with existing crops and derived-foods as the baseline. Accordingly, concepts of familiarity and substantial equivalence were advanced by OECD and WHO as ways to establish a risk analysis baseline for determining whether and to what extent risk/safety assessment was needed. Regulatory implementations of this paradigm have skewed to increasingly complex portfolios of studies rather than adhering to analysis which is formulated to fit the risk/safety questions relevant to a given case. Plants produced through genome editing technology will benefit from risk analysis that implements sound problem formulation to guide the need for and nature of risk/safety assessments.

Effect of common processing of soybeans on the enzymatic activity and detectability of the protein, Dicamba Mono-Oxygenase (DMO), introduced into dicamba-tolerant MON 87708

Assessing the safety of genetically engineered crops includes evaluating the risk (hazard and exposure) of consuming their newly expressed proteins. The dicamba monooxygenase (DMO) protein, introduced into soybeans to confer tolerance (DT) to dicamba herbicide, was previously characterized and identified to pose no food or feed safety hazards. Most agricultural commodities (e.g., soybeans, maize) enter the food supply after processing methods that can include exposure to high temperatures, harsh solvents or pH extremes that can adversely impact the structure and function of proteins. To understand the likelihood of exposure to DMO in foods from DT soy, enzymatically active and/or immunodetectable forms of DMO were measured in pilot-scale productions of two soy foods (soymilk and tofu), and eight processed fractions (full fat flour, inactivated full fat flour, defatted flour, toasted meal, protein isolate, protein concentrate, crude lecithin, and refined, bleached and deodorized oil). Western blot analysis detected DMO in tofu and in five of the eight processed fractions. DMO activity was not detected in either soymilk or tofu, nor in six of the eight processed fractions. Therefore, many commercial soy processing methods can denature and/or degrade introduced proteins, like DMO. Although the DMO protein has shown no evidence of hazard, this study demonstrates that processing further reduces any food or feed risk by limiting dietary exposure to intact DMO protein.

Oncolytic herpes simplex virus and immunotherapy

BACKGROUND

Oncolytic viruses have been proposed to be employed as a potential treatment of cancer. Well targeted, they will serve the purpose of cracking tumor cells without causing damage to normal cells. In this category of oncolytic viral drugs human pathogens herpes simplex virus (HSV) is especially suitable for the cause. Although most viral infection causes antiviral reaction in the host, HSV has multiple mechanisms to evade those responses. Powerful anti-tumor effect can thus be achieved via genetic manipulation of the HSV genes involved in this evading mechanism, namely deletions or mutations that adapt its function towards a tumor microenvironment. Currently, oncolytic HSV (oHSV) is widely use in clinical; moreover, there's hope that its curative effect will be further enhanced through the combination of oHSV with both traditional and emerging therapeutics.

RESULTS

In this review, we provide a summary of the HSV host antiviral response evasion mechanism, HSV expresses immune evasion genes such as ICP34.5, ICP0, Us3, which are involved in inducing and activating host responses, so that the virus can evade the immune system and establish effective long-term latent infection; we outlined details of the oHSV strains generated by removing genes critical to viral replication such as ICP34.5, ICP0, and inserting therapeutic genes such as LacZ, granulocyte macrophage colony-stimulating factor (GM-CSF); security and limitation of some oHSV such G207, 1716, OncoVEX, NV1020, HF10, G47 in clinical application; and the achievements of oHSV combined with immunotherapy and chemotherapy.

CONCLUSION

We reviewed the immunotherapy mechanism of the oHSV and provided a series of cases. We also pointed out that an in-depth study of the application of oHSV in cancer treatment will potentially benefits cancer patients more.

Engineered cell lines for fish health research

As fish farming continues to increase worldwide, the related research areas of fish disease and immunology are also expanding, aided by the revolution in access to genomic information and molecular technology. The genomes of most fish species of economic importance are now available and annotation based on sequence homology with characterised genomes is underway. However, while useful, functional homology is more difficult to determine, there being a lack of widely distributed and well characterised reagents such as monoclonal antibodies, traditionally used in mammalian studies, to help with confirming functions and cellular interactions of fish molecules. In this context, fish cell lines and the possibility of their genetic engineering offer good prospects for studying functional genomics with respect to fish diseases. In this review, we will give an overview of available permanently genetically engineered fish cell lines, as cell-based reporter systems or platforms for expression of endogenous immune or pathogen genes, to investigate interactions and function. The advantages of such systems and the technical challenge for their development will be discussed.

Transgenesis affects endogenous soybean allergen levels less than traditional breeding

The regulatory body that oversees the safety assessment of genetically modified (GM) crops in the European Union, the European Food Safety Authority (EFSA), uniquely requires that endogenous allergen levels be quantified as part of the compositional characterization of GM versions of crops, such as soybean, that are considered to be major allergenic foods. The value of this requirement for assessing food safety has been challenged for multiple reasons including negligible risk of altering allergen levels compared with traditional non-GM breeding. Scatter plots comparing the mean endogenous allergen levels in non-GM soybean isoline grain with the respective levels in GM grain or concurrently grown non-GM commercial reference varieties clearly show that transgenesis causes less change compared with traditional breeding. This visual assessment is confirmed by the quantitative fit of the line of identity (y = x) to the datasets. The current science on allergy does not support the requirement for quantifying allergen levels in GM crops to support safety assessment.

Formidable challenges to the notion of biologically important roles for dietary small RNAs in ingesting mammals

The notion of uptake of active diet-derived small RNAs (sRNAs) in recipient organisms could have significant implications for our understanding of oral therapeutics and nutrition, for the safe use of RNA interference (RNAi) in agricultural biotechnology, and for ecological relationships. Yet, the transfer and subsequent regulation of gene activity by diet-derived sRNAs in ingesting mammals are still heavily debated. Here, we synthesize current information based on multiple independent studies of mammals, invertebrates, and plants. Rigorous assessment of these data emphasize that uptake of active dietary sRNAs is neither a robust nor a prevalent mechanism to maintain steady-state levels in higher organisms. While disagreement still continues regarding whether such transfer may occur in specialized contexts, concerns about technical difficulties and a lack of consensus on appropriate methods have led to questions regarding the reproducibility and biologic significance of some seemingly positive results. For any continuing investigations, concerted efforts should be made to establish a strong mechanistic basis for potential effects of dietary sRNAs and to agree on methodological guidelines for realizing such proof. Such processes would ensure proper interpretation of studies aiming to prove dietary sRNA activity in mammals and inform potential for application in therapeutics and agriculture.

Diet-derived microRNAs: unicorn or silver bullet?

In ancient lore, a bullet cast from silver is the only effective weapon against monsters. The uptake of active diet-derived microRNAs (miRNAs) in consumers may be the silver bullet long sought after in nutrition and oral therapeutics. However, the majority of scientists consider the transfer and regulation of consumer’s gene activity by these diet-derived miRNAs to be a fantasy akin to spotting a unicorn. Nevertheless, groups like Dr. Chen-Yu Zhang’s lab in Nanjing University have stockpiled breathtaking amounts of data to shoot down these naysayers. Meanwhile, Dr. Ken Witwer at John Hopkins has steadfastly cautioned the field to beware of fallacies caused by contamination, technical artifacts, and confirmation bias. Here, Dr. Witwer and Dr. Zhang share their realities of dietary miRNAs by answering five questions related to this controversial field.

Emergency deployment of genetically engineered veterinary vaccines in Europe

On the 9th of November 2015, preceding the World Veterinary Vaccine Congress, a workshop was held to discuss how veterinary vaccines can be deployed more rapidly to appropriately respond to future epizootics in Europe. Considering their potential and unprecedented suitability for surge production, the workshop focussed on vaccines based on genetically engineered viruses and replicon particles. The workshop was attended by academics and representatives from leading pharmaceutical companies, regulatory experts, the European Medicines Agency and the European Commission. We here outline the present regulatory pathways for genetically engineered vaccines in Europe and describe the incentive for the organization of the pre-congress workshop. The participants agreed that existing European regulations on the deliberate release of genetically engineered vaccines into the environment should be updated to facilitate quick deployment of these vaccines in emergency situations.

Genetically engineered livestock for biomedical models. Transgenic Res. 2016;25:345-359. [PMID: 26820410 DOI: 10.1007/s11248-016-9928-6]

To commemorate Transgenic Animal Research Conference X, this review summarizes the recent progress in developing genetically engineered livestock species as biomedical models. The first of these conferences was held in 1997, which turned out to be a watershed year for the field, with two significant events occurring. One was the publication of the first transgenic livestock animal disease model, a pig with retinitis pigmentosa. Before that, the use of livestock species in biomedical research had been limited to wild-type animals or disease models that had been induced or were naturally occurring. The second event was the report of Dolly, a cloned sheep produced by somatic cell nuclear transfer. Cloning subsequently became an essential part of the process for most of the models developed in the last 18 years and is stilled used prominently today. This review is intended to highlight the biomedical modeling achievements that followed those key events, many of which were first reported at one of the previous nine Transgenic Animal Research Conferences. Also discussed are the practical challenges of utilizing livestock disease models now that the technical hurdles of model development have been largely overcome.

Activity and ecological implications of maize-expressed transgenic endo-1,4-β-D-glucanase in agricultural soils

Plant expression of thermostable endoglucanase (E1) has been proposed for improved conversion of lignocellulose to ethanol for fuel production. Residues of E1-expressing maize may affect ecological services (e.g., C mineralization and biogeochemical cycling) on soils where they occur. Therefore, the activity of residual E1 was investigated using soils amended with bacterial and plant-solubilized E1 compared with soil endogenous activity and residual activity from a mesostable cellulase (Aspergillus and Trichoderma spp.). An optimized analytical method involving a carboxymethyl cellulose substrate and dinitrosalicylic acid detection effectively assayed endoglucanase activity in amended and unamended soils and was used for determining E1 activity in 3 representative soils. The effect of E1 on soil carbon mineralization was determined by comparing CO(2) evolution from soils amended with transgenic E1-expressing and wild-type maize tissue. Extraction and recovery of the mesostable comparator, bacterial E1, and plant-soluble E1 showed nearly complete loss of exogenous endoglucanase activity within a 24-h period. Carbon mineralization indicated no significant difference between soils amended with either the transgenic E1 or wild-type maize tissue. These results indicate that maize residues expressing up to 30 µg E1/g tissue negligibly affect soil endoglucanase activity and CO(2) respiration for representative soils where transgenic E1 maize may be grown.