Browsing by Subject "Biotechnology"

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    56th Minnesota Nutrition Conference & Alltech, Inc. Technical Symposium, Proceedings, September 18-20, 1995, Bloomington, MN.
    (University of Minnesota: Dept. of Animal Science, Minnesota Extension Service, College of Veterinary Medicine, 1995)
  • Thumbnail Image
    Item
    Analysis of the U.S. Department of Agriculture's regulation of genetically engineered crops and reproductive biology of Carex pensylvanica (Lam.)
    (2013-08) McGinnis, Esther Ebata
    This dissertation is divided into two parts. Chapters 1 through 3 are interdisciplinary and focus on legal and scientific perspectives regarding the regulation of genetically engineered crops. Chapters 4 and 5 evaluated the environmental factors that control flowering in Pennsylvania sedge (Carex pensylvanica Lam.). The commercial potential of genetically engineered (GE) crops has not been fully realized in the United States due to environmental litigation that dramatically affected the pace of GE crop development and deregulation. The USDA's Animal and Plant Health Inspection Service (APHIS) regulates GE crops. However, litigation initiated by nongovernmental organizations exposed APHIS's vulnerability to lawsuits under the National Environmental Policy Act. We concluded in chapters 1 and 2 that APHIS did not adequately evaluate the environmental risks of novel crops, and thus left itself open to litigation. In Chapter 3, we described how the biotechnology industry is attempting to avoid regulation of GE crops through the creation of a non-plant pest loophole.Pennsylvania sedge is an upland forest sedge with horticultural potential as a low maintenance groundcover. For large plantings, achenes are preferred, but Pennsylvania sedge typically produces few achenes in its native habitat. As a first step in improving achene production, Chapter 4 evaluated the effect of vernalization and photoperiod on floral initiation and development. We concluded that Pennsylvania sedge is an obligate short day plant that does not require vernalization for flowering. Plants flowered when exposed to daylengths of 6 to 12 hours. Flowering was completely inhibited with 14-hour photoperiods. Chapter 5 examined the environmental factors that control floral gender sequence and inflorescence culm heights. Plants were found to be determined and florally initiated in the fall in the northern United States. A post-floral induction chilling treatment (winter) was necessary to produce protogynous flowering and normal inflorescence culm elongation.
  • Thumbnail Image
    Item
    Animals By Design
    (Minnesota Agricultural Experiment Station, 1998) University of Minnesota. Agricultural Experiment Station
  • Thumbnail Image
    Item
    Developing Methods To Overcome The Bottlenecks In Plant Gene Editing
    (2020-10) Nasti, Ryan
    Altering plant species to make crops for human use is a centuries old practice. Through traditional breeding, most of the extant crop varieties used today have been optimized to increase yield and growth potential. Despite advancements over time, current breeding is limited in its throughput. In order to address increasingly problematic issues such as climate change, a multitude of technologies have been developed to improve the speed and ease of this process. Technologies such as CRISPR/Cas based gene editing and innovative plant transformation methods promise to greatly democratize the ability to generate new cultivars of crops. Plant gene editing is typically performed by delivering gene editing reagents (e.g. Cas9 and sgRNAs) to explants in culture. Edited cells are induced to differentiate into whole plants by exposure to various hormone regimes. This process serves as a major bottleneck in current plant biological studies since creating edited plants through tissue culture has many drawbacks: the process is often inefficient, requires considerable time, works with limited species and genotypes, and causes unintended changes to the genome and epigenome. Developing methods to circumvent these issues by allowing for simpler delivery and less intensive regeneration across a wide number of species would obviate this bottleneck. Looking first to optimize editing reagent delivery, a simple and scalable reagent delivery method was required. To this end, improvements were made to existing Agrobacterium tumefaciens based co-culture methods, yielding a streamlined fast treated co-culture (Fast-TrACC) reagent delivery method for rapid reagent testing. The Fast-TrACC procedure combines treatment of Agrobacterium to increase T-DNA transfer and a luciferase reporter to allow for high-throughput screening after co-culture. Application of this method to deliver reporters, gene editing components and test expression elements in a number of dicot species has successfully demonstrated the broad usefulness of this delivery method. Next looking at the major bottleneck of regeneration, ways to overcome the tedious and time consuming nature of current regeneration practices were necessary. Advances in ectopic expression of plant developmental regulators have demonstrated the feasibility of inducing somatic cells to form meristems. A high-throughput method was developed to optimize combinations of developmental regulators for induction of meristems on dicot seedlings. After analysis of several different developmental regulator combinations, the combinations of ZmWUS2 & AtSTM as well as ZmWUS2 & ipt were found to be most effective in generating de novo shoots. When these developmental regulators are co-delivered with gene editing reagents, induced meristems produce fertile plants that transmit gene edits to progeny. The de novo induction of gene edited meristems sidesteps the need for tissue culture, promising to overcome a current bottleneck in plant gene editing. These methods were designed and established to function effectively in the model plant, Nicotiana benthamiana, but application in a crop species, such as tomato, is necessary to realize the technology’s full potential. Classical editing with tissue culture in tomatoes has been used to alter traits such as locule number and branching. Despite this ability to generate desired mutations, the key bottlenecks still exists in regenerating whole plants after editing has occurred. This limitation comes from the combination of tedious explant manipulation and subsequent regeneration. Based upon the inferences made from N. benthamiana, ectopic overexpression of ZmWUS2 & ipt was shown to promote re-differentiation of somatic tissues into meristems. By combining DRs with gene editing reagents, we have demonstrated edited tomato lines can be quickly established, thus circumventing the need for tissue culture. Using these tools, new avenues of engineered across plant species become more accessible, thus allowing for improvements in accelerated breeding, de novo domestication and reengineering metabolism in a simpler fashion than what was previously been possible.
  • Thumbnail Image
    Item
    Genomic Analysis And Engineering Of Chinese Hamster Ovary Cells For Improved Therapeutic Protein Production
    (2020-05) O'Brien, Sofie
    Protein biologics have transformed the field of medicine in recent years. These complex molecules are produced in living cells, primarily Chinese Hamster Ovary (CHO) cells. Due to the importance of these therapeutic proteins to disease treatment, it is essential to improve the efficiency of their production, both to promote the development of new therapies, and to bring down the cost of manufacturing. One of the most important components of the production process is the development of a cell line. Many features of a cell line, such as cellular growth, metabolism, and the integration site of the gene encoding the protein, influence the resulting culture productivity and quality of the protein produced. In this thesis, multiple aspects of the relationship between integration site and resulting cell line behavior were investigated. First, a rapid integration site identification method was developed to facilitate further analysis of integration sites in complex cell lines. Next, to examine genomic instability, parental cells were compared with high and low producing subclones, leading to identification of genomic regions vulnerable to copy gain/loss. A large-scale analysis across many CHO cell lines was further performed to look for global regions of genomic variation, independent of an individual cell line. To evaluate integration sites with high transcriptional potential, integration sites from high producing cells were examined, and high transgene expression was correlated to high transcriptional activity and accessibility of the integration region. This work also extended to energy metabolism, another key feature of a cell line. Through the use of model guided multi-gene engineering to manipulate cell metabolism, waste product generation was reduced in late-stage culture. With these tools and technologies, we can build a more complete picture of a desirable integration site, which can be used to drive the development of next generation cell lines with high, stable expression of transgenes for therapeutic protein production.
  • Thumbnail Image
    Item
    Navigating the stages of innovation: a study of the U.S. biotechnology industry.
    (2010-07) Dahlin, Eric Carl
    My dissertation takes a broad view of innovation by investigating product success among U.S. biotechnology firms across various stages of innovation including product discovery, product development, and product success. Current explanations of biotechnology product success examine one or two stages of innovation and underscore the importance of strategic alliances. However, current explanations are incomplete. First, they fail to examine whether their explanations hold across the entire innovation process. Second, estimates suggest that up to 70% of strategic alliances fail to meet their objectives (Kale and Singh 2009) and product develop remains very costly despite the high incidence of alliances in the biotechnology industry. I propose that success across the stages of innovation is associated with the scope of learning that occurs within the firm, among strategic alliance partners, and from a focal firm's network. That is, product discovery is associated with learning within the firm, product development is associated with learning among strategic alliance partners, and product success is associated with learning from the firm's overall network. While entering strategic alliances to pool resources to defray the costs of innovation is likely a necessary condition for innovation success current research overlooks the role of product development strategies. In this study I examine product development strategies that influence the likelihood of innovation success including exploration, exploitation, and ambidexterity (i.e., the simultaneous pursuit of exploration and exploitation strategies). Moreover, findings from interviews with executives in biotechnology firms provide insight into the strategies firms use to develop new drugs and evaluate them at various stages of innovation. Results from regression models support the general proposition that success at different stages of innovation varies with the scope of learning. Learning at the organizational-level (firm age and absorptive capacity) is likely to increase success at the discovery stage. Alliance partnerships are sources of learning (research alliance and development alliances) that affect product development. Network-level learning (network centrality and network experience) influences sales growth, but only for smaller firms in my sample. I also find that ambidexterity product development strategies are statistically significant predictors of success at each stage of innovation.