Methods of Evaluation in Orthopaedic Animal Research
Yuehuei H. An, Richard J. Friedman in Animal Models in Orthopaedic Research, 2020
The basic terminology given here is adapted from the reviews by Shore and Kaplan.251,252 A gene is a unit of heredity, consisting of a segment of chromosomal DNA that is required for production of a functional protein or RNA. The gene contains both coding and regulatory regions. A transgene is a foreign gene which has been spliced into an animals original genomic DNA. mRNA is a type of RNA that contains protein coding information. Nucleotide sequence refers to the order of nucleotides in a given segment of DNA or RNA. Translocation is the transfer of a portion of DNA from one chromosome to another. A probe is a DNA or RNA molecule that is labeled, or tagged, and can then be used to locate a complementary DNA or RNA strand through hybridization. Vectors are DNA molecules that are used as carrier molecules for cloned DNA sequences. They contain information which allows recombinant molecules to be replicated in host bacterial cells. A plasmid is a small circular double-stranded DNA molecule which is found in bacteria and replicates independently of the host chromosome. They are commonly used as vectors in molecular cloning. A recombinant DNA molecule is a DNA molecule containing segments of DNA from different origins, such as a piece of human DNA that has been joined to a plasmid DNA. A clone is a term used to describe identical segmental DNA molecules produced by recombinant DNA technique. Molecular cloning is a process by which a specific segment of DNA is isolated and then numerous identical copies, or clones, of that segment of DNA are generated.
Sources of Essential Oils
K. Hüsnü Can Başer, Gerhard Buchbauer in Handbook of Essential Oils, 2020
Genetic engineering is defined as the direct manipulation of the genes of organisms by laboratory techniques, not to be confused with the indirect manipulation of genes in traditional (plant) breeding. Transgenic or GMOs are organisms (bacteria, plants, etc.) that have been engineered with single or multiple genes (either from the same species or from a different species), using contemporary molecular biology techniques. These are organisms with improved characteristics, in plants, for example, with resistance or tolerance to biotic or abiotic stresses such as insects, disease, drought, salinity, and temperature. Another important goal in improving agricultural production conditions is to facilitate weed control by transformed plant resistant to broadband herbicides like glufosinate. Peppermint has been successfully transformed with the introduction of the bar gene, which encodes phosphinothricin acetyltransferase, an enzyme inactivating glufosinate ammonium or the ammonium salt of glufosinate, phosphinothricin, making the plant insensitive to the systemic, broadspectrum herbicide Roundup (Roundup Ready mint) (Li et al., 2001).
The Challenge of Parasite Control
Eric S. Loker, Bruce V. Hofkin in Parasitology, 2015
Clearly, new strategies for vector control are required. One promising approach is the development of transgenic vectors with reduced vector capacity (see Chapter 3, pages 81–82). Transgenesis refers to the deliberate introduction of exogenous genetic material into a living organism. The newly acquired genes, called transgenes, endow the recipient organism with new properties that will be transmitted to progeny. If vector capacity can be reduced with this technique, the hope is that transgenic vectors can be released into areas of endemicity, resulting in reduced transmission and morbidity. Such genetic methods, usually used in tandem with more conventional control, have been under investigation since the 1950s. The operational application of genetically altered vectors to reduce transmission has proven to be one of the most difficult challenges of vector control.
How necessary are animal models for modern drug discovery?
Published in Expert Opinion on Drug Discovery, 2021
Transgenic animals have a foreign gene introduced into their genome. Such animals are usually produced by DNA microinjection into the pronuclei of a fertilized egg that is subsequently implanted into the oviduct of the surrogate mother. Transgenic animals have become a key tool in functional genomics in order to generate models for human diseases and validate new drugs [20]. Transgenesis includes the addition of foreign genetic information to animals and specific inhibition of endogenous gene expression. The knockout animals are transgenic that have a specific interest gene disabled are transgenic, and are widely used to investigate both normal gene function, as well as the analyses of patho-biological roles of select genes involved in various disease states [21]. In addition, such transgene/knockout animal models are actively used in the development of new therapeutics and associated strategies.
Locked and loaded: engineering and arming oncolytic adenoviruses to enhance anti-tumor immune responses
Published in Expert Opinion on Biological Therapy, 2022
Replacing a viral ORF with a transgene ORF utilizes the intrinsic viral expression program to express transgenes. It can make transgenes express as if they were early, intermediate, or late genes for programmed expression. It also entrains transgene expression into the viral program such that if the viral genes are not activated, the transgenes might not be expressed. This ORF substitution strategy has advantages in minimizing transgene cassette space over other approaches that require external regulatory sequence elements. As we reviewed, E1B and E3 genes are non-essential for viral replication and virion production, thus making those genes potential candidates for replacement with therapeutic transgenes. Terry Hermistons group has shown that E3-CR1-α(6.7 K)/gp19K, E3-ADP, and E3-RID-α/β/E3-14.7 K regions can be replaced by a transgene or multiple transgenes (Figure 2) [70–73]. Reporter and IFN genes also have been inserted in E3B regions [74]. Notably, the choice of exact insertion sites in the complex E3 region can affect neighboring E3 ORFs expression and the overall viral fitness [72]. This approach can save some space; however, human Ads do not replicate well in most mouse cells and other animal cells. Therefore, transgene cassettes that piggyback their expression on Ads’ transcripts will probably not be expressed well in some animal models of cancer.
Clinical development on the frontier: gene therapy for duchenne muscular dystrophy
Published in Expert Opinion on Biological Therapy, 2020
Damon R. Asher, Khampaseuth Thapa, Sachi D. Dharia, Navid Khan, Rachael A. Potter, Louise R. Rodino-Klapac, Jerry R. Mendell
Gene transfer therapy is designed to treat the underlying genetic cause of a disease. The intent is to deliver a transgene that will compensate for a disease-causing mutation in patients. The concept is straightforward but clinical implementation of the idea is complex. Realization of the promise of gene therapy has awaited the development of safe methods to deliver transgenes to relevant tissues and specifically express them there. Further complications are introduced by factors specific to rare diseases and the single-dose nature of current gene transfer treatments. Here, we will review considerations for the construction of a gene transfer therapy agent and the evaluation of its effectiveness, guided by our experience in developing a gene therapy to treat Duchenne muscular dystrophy (DMD).