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Competent Cell Preparation and Transformation of Pichia pastoris
Joan Lin-Cereghino, Christopher A. Naranjo, and Geoff Lin-Cereghino
During the past three decades, the methylotrophic yeast Pichia pastoris (recently reclassified as Komagataella phaffii) has gained widespread acceptance as a system of choice for heterologous protein expression. One of the reasons that this yeast is used so frequently is the simplicity of techniques required for its molecular genetic manipulation. There are several different protocols available for introducing DNA into P. pastoris using electroporation or heat shock. We describe here a shortened protocol for cell preparation and transformation that works reliably with either prototrophic markers or antibiotic selection in this host. This procedure utilizes the most efficient portions of the electroporation and heat-shock transformation protocols to yield a method that is both time-saving and effective.
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Using Writing in Science Class to Understand and Activate Student Engagement and Self-Efficacy
Eileen K. Camfield, Laura Beaster-Jones, Alex D. Miller, and Kirkwood M. Land
Writing is an active learning strategy strongly linked to student engagement. Student-authored learning narratives can reveal powerful self-beliefs that can either activate or inhibit success. In this targeted study of the aspect of student engagement most associated with self-beliefs (i.e., self-efficacy), students in separate sections of an introductory college biology course taught by the same professor were divided into experimental and control groups. The experimental group participated in an additional 1-unit required study skills component featuring writing-to-learn and self-efficacy development strategies. One hundred forty “pre” and “post” student self-efficacy narratives written in both cohorts were scored and also thematically coded. Scoring revealed a Cohen’s effect size d = 0.63 for the experimental group, but only d = 0.28 for control. Thus, writing appears to activate student self-efficacy most if it is part of a deliberate and sustained campaign. Gains seemed particularly impactful for struggling students, as the experimental group also saw significantly fewer students, with unmet fundamental skills, earning Ds and Fs in the course than those in the control group. Subsequent student interviews were also analyzed and informed recommendations for future research and pedagogical practice.
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Prebiotics, Probiotics, and Bacterial Infections
Christina C. Tam, Kirkwood M. Land, and Luisa W. Cheng
Bacterial pathogens have developed exquisite virulence mechanisms to survive in the host cells. These virulence mechanisms help them bind and internalize into host cells, replicate, and evade the host immune response. The mammalian host itself has developed its own repertoire of weapons to prevent this from happening. One important component of host response in preventing infections in the gut lumen is the diverse commensal microbiota present. Dysbiosis of the gut microbiota has been implicated in the development of many gastrointestinal diseases. A potential therapeutic pathway to solve these diseases would be by providing probiotics and/or prebiotics to help stimulate growth of the beneficial commensal bacteria. Here, we will present evidence of commensal microbiota imbalance in the development of disease as well as potential therapies to restore gut harmony.
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Technologies for Detecting Botulinum Neurotoxins in Biological and Environmental Matrices
Luisa W. Cheng, Kirkwood M. Land, Christina C. Tam, D. L. Brandon, and L. H. Stanker
Biomonitoring of food and environmental matrices is critical for the rapid and sensitive diagnosis, treatment, and prevention of diseases caused by toxins. The U.S. Centers for Disease Control and Prevention (CDC) has noted that toxins from bacteria, fungi, algae, and plants present an ongoing public health threat, especially since some of these toxins could compromise security of the food supply. Botulinum neurotoxins (BoNTs), produced by Clostridium spp., are among those bacterial toxins that pose life-threatening danger to humans. BoNTs inhibit the release of acetylcholine at peripheral cholinergic nerve terminals and cause flaccid paralysis. BoNTs are grouped in seven serotypes and many subtypes within these groups. Rapid and accurate identification of these toxins in contaminated food as well as in environmental matrices can help direct treatment. Herein, we discuss current methods to detect BoNTs with a focus on how these technologies have been used to identify toxins in various food and environmental matrices. We also discuss the emergence of new serotypes and subtypes of BoNTs and the increasing number of cases of botulism in wildlife. Finally, we consider how environmental changes impact food safety for humans and present new challenges for detection technology.
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Current methods for detecting the presence of botulinum neurotoxins in food and other biological samples
Luisa W. Cheng, Kirkwood M. Land, and L. H. Stanker
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The botulinum neurotoxin: a deadly protease with applications to human medicine
Kirkwood M. Land and Luisa W. Cheng
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An in vivo assay for a plasmid replication initiation protein
Aresa E. Toukdarian, Joan Lin-Cereghino, and Donald R. Helinski
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The expression of viral and cellular genes in papillomas of the choroid plexus induced in transgenic mice
Jeffrey R. Marks, Joan Lin-Cereghino, Douglas Miller, G. Lozano, J. Herbert, and Arnold J. Levine
A selection of books and book chapters written or edited by faculty in the College of the Pacific - Department of Biological Sciences at University of the Pacific.
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