Organismal Biological Physiology Commons^™

Genome-Scale Metabolic Modeling Of Chitin-Degrading Microbial Systems, Aimee Kristin Kessell

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

As a major component of fungal cell walls and exoskeletons of invertebrates, chitin is widespread in soils, constituting the second most abundant biopolymer in nature. Composed of N-acetyl-D-glucosamine chains, it serves as a vital source of nutrients, including both carbon and nitrogen, for the growth of microorganisms. A solid understanding of the microbial degradation of chitin is critical for predicting their impacts on biogeochemical cycling in soil ecosystems. Organisms that degrade biopolymers (degraders) produce energetically expensive extracellular enzymes to break down complex organic carbons into simpler labile forms that are sharable with other species, including those that do not contribute …

Discovering Novel Polyextremotolerant Fungi And Determining Their Ecological Role Within The Biological Soil Crust Consortium, Erin C. Carr

School of Biological Sciences: Dissertations, Theses, and Student Research

The ecological niche of polyextremotolerant fungi within oligotrophic ecosystems such as biological soil crusts has not yet been determined. These fungi persist in locations where nutrients are depleted while simultaneously surrounded by autotrophic microbes such as algae and cyanobacteria. Yet it has not been shown that they are engaging in any exchange of nutrients the way lichens do. However, there is seemingly no other way for these fungi to obtain vital nutrients, such as carbon or nitrogen, other than from these microbes. Here we have isolated polyextremotolerant fungi from cold desert biological soil crusts which are a microbial biofilm that …

Gut Symbiont Viability In Honey Bees Exposed To Agrochemical Stressors, Bryant Justin Gabriel

Department of Entomology: Dissertations, Theses, and Student Research

The honey bee gut microbiome is essential for protecting this pollinator against abiotic and biotic stressors, including the prevention of harmful gut parasites and pathogens. Previous studies have not only demonstrated a linkage of bee gut dysbiosis to increased immunodeficiencies and pathogen sensitivities, but also report the maladaptation of the gut microbiome in bees exposed to agricultural and apicultural chemistries. There are few techniques available that allow for a simple and reliable analysis of the relative proportions of live and dead gut microbes in bees exposed to these chemistries. Previous techniques for measuring gut symbiont dysbiosis are temporally limited by …

Characterization And Investigation Of Fungi Inhabiting The Gastrointestinal Tract Of Healthy And Diseased Humans, Mallory J. Suhr

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Gastrointestinal microbiome studies have failed to include fungi in total community analyses. As a result, their diversity and function in the gut is poorly understood. Recent work has begun to uncover the role intestinal fungi play in diet, immune system development, interactions with other microorganisms in the gut, and pathogenesis of diseases. Advances in sequencing technologies allow for the ability to profile the fungal gut microbiome (“mycobiome”) in healthy and diseased states. This thesis explores the mycobiome in 1) healthy humans with a vegetarian diet and 2) pediatric small bowel transplant recipients that develop fungal bloodstream infections.

The gut mycobiome …

Promises And Prospects Of Microbiome Studies, Maria C. Rivera, Jacques Izard

Department of Food Science and Technology: Faculty Publications

Since Anthony van Leeuwenhoek, first microscopic observations of the unseen microbiota and the more recent realization that little of the microbes in the biosphere are known, humans have developed a deep curiosity to fully understand the inner workings of the microbial realm. Our ability to characterize the complexity of microbial communities in their natural habitats has dramatically improved over the past decade thanks to advances in high-throughput methodologies. By eliminating the need to isolate and culture individual species, metagenomics approaches have removed many of the obstacles that hindered research in the ecology of mixed microbial consortia, providing valuable information about …

Characterization Of The Ecological Role Of Genes Mediating Acid Resistance In Lactobacillus Reuteri During Colonization Of The Gastrointestinal Tract, Janina A. Krumbeck, Nathan L Marsteller, Steven Frese, Daniel A. Peterson, Amanda Ramer-Tait, Robert W. Hutkins, Jens Walter

Department of Food Science and Technology: Faculty Publications

Rodent-derived strains of Lactobacillus reuteri densely colonize the forestomach of mice and possess several genes whose predicted functions constitute adaptations towards an acidic environment. The objective of this study was to systematically determine which genes of L. reuteri 100-23 contribute to tolerance towards host gastric acid secretion. Genes predicted to be involved in acid resistance were inactivated, and their contribution to survival under acidic conditions was confirmed in model gastric juice. Fitness of five mutants that showed impaired in vitro acid resistance were then compared through competition experiments in ex-germ-free mice that were either treated with omeprazole, a proton-pump inhibitor …

Thoughts On Quorum Sensing And Fungal Dimorphism, Kenneth W. Nickerson, Audrey L. Atkin, Jessica C. Hargarten, Ruvini U. Pathirana, Sahar Hasim

Papers in Microbiology

Farnesol has been best studied for its role in regulating fungal dimorphism. However, farnesol is also a lipid and in this review we analyze data relevant to farnesol’s function and synthesis from the perspective of farnesol and bacterial endotoxins acting as membrane active compounds. This analysis implicates the possible roles of: (1) endotoxins in the regulation of farnesol production by C. albicans; (2) farnesol in the interactions between C. albicans and the host during disseminated infections; and (3) ubiquinones in the mechanisms for unusually high resistance to farnesol by some C. albicans cell types. Finally we discuss the implications …

Archaeoparasitology Of Chaco Canyon, Rachel Paseka

Department of Environmental Studies: Undergraduate Student Theses

Ancient cultures of the Colorado Plateau have been a focus of archaeoparasitology since its inception, and a vast parasitological history is recorded in coprolites preserved in this arid region. The inhabitants of Chaco Canyon dominated Ancestral Puebloan culture between 1050 and 1120 AD and were responsible for the construction of great towns, road systems, and early agriculture. Analysis of the parasites preserved in fecal remains contributes to an increased knowledge of ancient Chacoan health and culture. Nineteen coprolites from four sites in Chaco Canyon were rehydrated and analyzed microscopically for parasite remains. Rhabditiform and filariform nematode larvae were found from …

Cryo-Electron Tomography Elucidates The Molecular Architecture Of Treponema Pallidum, The Syphilis Spirochete, Jacques Izard, Christian Renken, Chyong-Ere Hsieh, Daniel C. Desrosiers, Star Dunham-Ems, Carson La Vake, Linda L. Gebhardt, Ronald J. Limberger, David L. Cox, Michael Marko, Justin D. Radolf

Department of Food Science and Technology: Faculty Publications

Cryo-electron tomography (CET) was used to examine the native cellular organization of Treponema pallidum, the syphilis spirochete. T. pallidum cells appeared to form flat waves, did not contain an outer coat and, except for bulges over the basal bodies and widening in the vicinity of flagellar filaments, displayed a uniform periplasmic space. Although the outer membrane (OM) generally was smooth in contour, OM extrusions and blebs frequently were observed, highlighting the structure’s fluidity and lack of attachment to underlying periplasmic constituents. Cytoplasmic filaments converged from their attachment points opposite the basal bodies to form arrays that ran roughly …

Karyotype Of Geomys Pinetis (Mammalia: Geomyidae), With A Discussion Of The Chromosomal Relationships Within The Genus, S. L. Williams, Hugh H. Genoways

University of Nebraska State Museum: Mammalogy Papers

Summary. Four of the five subspecies of Geomys pinetis were karyotyped. All specimens examined had a diploid number of 42 and a fundamental number of 80. This karyotype was compared with the described karyotypes of other species of Geomys and was considered to be derived from an ancestoral form having a karyotype of about 70 acrocentric elements.

The Relation Between Metabolism And Potassium Cyanide Inhibition In Pelomyxa Carolinensis, Tatsuru Eugene Kimura

Open Access Master's Theses (through 2010)

1. Introductlon ( Respiratory System)

2. Introduction ( Protozoan Experiments)

3. Materials and Method

a . Experimental Organism

b. Barcroft-Warburg Micro-respirometer

c. Manometric Calibration

4 . Results

a . The Effect ot Temperature

b. The Effect of Potassium Cyanlde

5 . Discussion

6. Summary

7. Bibliography

The thesis investigates the following problems: (1) whether or not there is any correlation between temperature change and respiratory quotient, (2) whether or not respiratory inhibition by cyanides is influenced by temperature, and (3) whether or not the cytochrome-cytochrome oxidase type of respiratory system is concerned chiefly with carbohydrate metabolism in Pelomyxa carolinensis.