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Genetics of muscle mass and strength
Published in Adam P. Sharples, James P. Morton, Henning Wackerhage, Molecular Exercise Physiology, 2022
Stephen M. Roth, Henning Wackerhage
At the end of this chapter, we will discuss the results of selective breeding and inbred mouse strain studies as a non-biased strategy to identify genes that affect muscle mass and/or strength. Apart from farmers and horse breeders, geneticists have performed selective breeding experiments to (a) identify the cumulative effect of selecting, in the ideal case, all DNA sequence variants within a population that affect muscle size and (b) identify these DNA sequence variants. Selection studies for body weight have also led to an accumulation of genetic variants or alleles that increase or decrease muscle mass, as muscle mass is related to body mass. For example, the gastrocnemius weight in males of the so-called DUH mouse strain that have high body mass is ≈247 mg, whilst the gastrocnemius weight of mice selected for small body weight reaches only ≈66 mg (25). Among the selected alleles, there might be some that affect the growth of all cells such as genetic variations in the growth hormone system and alleles that affect muscle mass specifically such as those in the myostatin-Smad pathway.
Alopecia Areata in Aging C3H/HeJ Mice
Published in John P. Sundberg, Handbook of Mouse Mutations with Skin and Hair Abnormalities, 2020
John P. Sundberg, Colleen M. Vallee, Lloyd E. King
Retired female C3H/HeJ mice were submitted to the Jackson Laboratory Diagnostic Laboratory in 1991 because of a sporadic occurrence of alopecia. Investigation of one colony revealed that primarily female mice of this strain, 6 months of age and older, were affected. Subsequently, this disease has been identified in both males and females in other research colonies of C3H/HeJ mice that were held until 18 months of age. Selective breeding has increased the incidence within specific lines.1
A Brief History of Genetic Therapy: Gene Therapy, Antisense Technology, and Genomics
Published in Eric Wickstrom, Clinical Trials of Genetic Therapy with Antisense DNA and DNA Vectors, 2020
Other early efforts at genetic manipulation were empirical, employing phenotype, the physical manifestation of genetic forces, to predict the outcome of genetics. Although crude by today's standards, an understanding of genetics through phenotype proved simple and powerful. The selective breeding of animals and crops, which has taken place worldwide over centuries, is a testament to the potency of the phenotypic approach to genetics.
Human Brain Surrogates Research: The Onrushing Ethical Dilemma
Published in The American Journal of Bioethics, 2021
This issue is about how we might use, or misuse, human brain surrogates, or the research on them, outside of research. At the science fiction extreme, Robert A. Heinlein’s short story, Jerry Was a Man, depicts a world where non-human animals were genetically modified in many ways, including producing intelligent dwarf elephants as pets and cognitively enhanced chimpanzees as farm workers (Heinlein 1947). Similarly, the Planet of the Apes series—from the original French book through the nine movies and one television series (so far)—is another version of the same approach (Boulle 1963; see IMDB for the movies). These seem wildly unrealistic, at least today. But consider how we have bred various traits into our domestic animals, using old fashioned selective breeding. For some of them, including some types of dogs, the breeding has led to at least some enhanced cognitive skills. (Ever seen a sheep dog working?) Might we do the same through genome editing or chimeras? Would that be good or bad—or, most likely, would “it depend”?
Models of retinal diseases and their applicability in drug discovery
Published in Expert Opinion on Drug Discovery, 2018
Goldis Malek, Julia Busik, Maria B Grant, Mayur Choudhary
Diabetes models are generated typically through drugs, diet, or chemical damage. Genetic models are produced by selective breeding and gene editing. Mice have been the emphasis of most genetic studies, with the discovery of inherited obesity or hyperglycemia resulting in a diabetic phenotype [152–154]. However, other species have advances over rodent DR models. As put forth by Engerman, dog models appear to be most similar to human DR [155]. Pigs are preferred for the similarity of their eye structure to humans and Zebra fish for their short life span and large breeding sizes [156]. Unfortunately, nonhuman primates have proven relatively resistant to induced DR [157]. Although no single animal model represents the complete range of vascular and neural complications of human DR from both early and late stages, the murine models described below and summarized in Table 2 have been instrumental in establishing mechanisms responsible for DR and have provided reproducible preclinical data.
Echinacea biotechnology: advances, commercialization and future considerations
Published in Pharmaceutical Biology, 2018
Jessica L. Parsons, Stewart I. Cameron, Cory S. Harris, Myron L. Smith
Conventional selective breeding techniques have traditionally led to the gradual improvement of many plant species. While industry will undoubtedly continue to develop “improved” varieties, published Echinacea breeding studies (and patents) have focused primarily on ornamentals (Ault 2002; Korlipara 2008) and reducing seed dormancy (Qu and Widrlechner 2012). Traditional selective breeding of Echinacea can make use of the existing genetic and phenotypic variation in commercial and wild collected plants and is widely accepted by the public, including within the organic farming industry. Conversely, direct alteration of the genome of a plant through molecular genetic techniques is the most precise way to modify developmental and biosynthetic processes. Whereas public concerns will likely continue to impede the use of Genetically Modified Organisms (GMOs), several potentially “organically acceptable” biotechnological approaches have been developed to modify Echinacea, including transformation with Agrobacterium and the induction of polyploids.