Celebration of Student Research 2021
College of Science students who volunteered to share their research are featured here
In addition to the student work shared below you can see the winners of the RSCA conference who represented the College of Science at the CSU Student Research Competition.
SEE THE RSCA CONFERENCE WINNERS FROM THE COLLEGE OF SCIENCE
One of those students, Justin Cortez, chemistry and biochemistry, won first place first place in the Physical and Mathematical Sciences category at the CSU Student Research Competition. You can see his presentation by clicking on the link above.
Suhani Bhakta
Graduate Student, Biological Science
Faculty Mentor: Frances Mercer
Research: Determining the role of neutrophil extracellular degranulation in the trogocytic killing of Trichomonas vaginalis
Abstract:
Trichomonas vaginalis, an extracellular protozoan is the causative agent of trichomoniasis, the 3rdmost common sexually transmitted infection (STI) worldwide. There are roughly 400 million cases worldwide, however, due to asymptomatic individuals, the number of cases is expected to be a lot greater. Common symptoms of trichomoniasis include but are not limited to discharge, pain during urination, and inflammation of the prostate and cervix. The inflammatory response to Tv is attributed to the immune response, specifically neutrophils, which are the most abundant immune cell type present at the site of infection. Neutrophils use trogocytosis, “to nibble,” to kill Tv. During trogocytosis, multiple neutrophils swarm around one trichomonad, make contact, and disrupt the parasite plasma membrane by nibbling at it. The trogocytic killing mechanism used by neutrophils is not well understood, however, serine proteases have shown involvement in neutrophil trogocytic killing of Tv. Serine proteases are found at the plasma membrane of neutrophils and within toxic granules of neutrophils. Toxic granules contain digestive enzymes that aid in killing extracellular pathogens when released from the cell in a process known as extracellular degranulation. To determine if contact-dependent extracellular degranulation is involved in the trogocytic killing of Tv, stxbp2, a gene that is required for extracellular degranulation, was knocked out from cell line HL-60 using CRISPR Cas9 ribonucleoprotein (RNP). We hypothesize toxic granules released from neutrophils onto the surface of Tv aids in forming fragments, which are then taken up by neutrophils. Functional assays containing knockout cells and Tv will determine if extracellular degranulation is involved in the trogocytic killing of Tv.
Caitlin Doherty
Graduate Student, Biological Science
Faculty Mentor: Andrea Bonisoli-Alquati
Research: The effects of ionizing radiation on mutation rate in animals: A meta-analysis
Abstract:
Exposure to ionizing radiation can result in increases in mutation rate through direct energy deposition on DNA molecules, or indirectly through the generation of reactive oxygen species, causing double-stranded or single-stranded breaks, respectively. Failure of DNA repair mechanisms can result in gene mutations or chromosome aberrations. The effects of low-dose ionizing radiation on mutation rate vary throughout the literature, yet there are no systematic reviews which explain the sources of variation. The purpose of this systematic review and meta-analysis of published studies is to characterize how the effects of low-dose ionizing radiation on mutation rate vary due to the radiation source, dose received, molecular approach, and taxonomic variation. My literature search retrieved 545 estimates of effect size from 153 studies on 20 different species, 84% of which are from humans. Mutation rate was determined for animal species sampled from natural populations in contaminated regions using large and small-scale molecular detection methods. To determine the magnitude of the effects caused by low-dose ionizing radiation, mutation rate was extracted from each study and measures of effect were standardized by calculating Fisher’s z-transformed correlation coefficients (Zr). Variation across animal taxa will be analyzed using life history traits in models accounting for phylogenetic relatedness. I expect mutation rates determined from unstable chromosome aberrations and micronuclei will have larger effect sizes due to their specificity in detecting radiation exposure. The results of this study will help clarify the biological effects of radiation exposure and aid in risk assessment of animal species in contaminated environments.
Danielle LaVine
Mathematics Major
Faculty Mentor: Adam King
Research: Species Conservation in North American Forests, 1982-2020
Abstract:
The International Union for Conservation of Nature (IUCN) works to promote conservation and sustainability worldwide. One of their major projects for understanding and promoting conservation efforts is through their Red List of Threatened Species. We wish to understand how the conservation status of species inhabiting North American forests has changed over time. We use mixed-effects models to estimate the Red List status of forest-dwelling North American species in an age-period-cohort analysis using data from 1982 to 2020. In our analysis, we will evaluate several models that include different combinations of age, period, and cohort, as well as additional predictors such as the taxonomy of the species included in our data. We also examine how the inclusion of random effects improves or worsens our model estimates. We find that models including age and cohort typically perform better than models using alternative combinations of age, period, and cohort. The models we develop provide evidence of declining conservation status among species inhabiting North American forests that can be attributed to age and cohort effects.
Zuhayr Khan
Biotechnology Major
Principal Investigator/Faculty Mentor: Dr. Glenn Kageyama
Research: A Possible Novel Mechanism for Cognitive Resistance to Neurodegeneration: Modulation of Interneuron Activity in the Hippocampus After Exposure to Enriched Environments
Background:
Exposure to an enriched environment has been shown in many studies to be beneficial to brain structure and cognition by preserving neuronal integrity and strengthening the functioning and plasticity of neural circuits. These benefits derive from the added spatial, social, and sensory complexities in an enriched environment. It has been well known for a few decades that an enriched environment stimulates neurogenesis and cell proliferation in the dentate gyrus of the hippocampus, leading to an increased number of dentate granule cells (DGCs). However, the changes to other populations of cell types, particularly interneurons, has remained elusive. Interneurons are integral regulators of neurotransmission in the hippocampus. Damage to hippocampal interneurons have serious implications and lead to a decline in cognitive health. Our study sought to elucidate possible changes in interneurons affected by exposure to an enriched environment (EE) and enriched changing (EC) environment.
Method:
The topographic distribution of nicotinamide adenine dinucleotide phosphate-diaphorase(NADPHd) positive neurons was studied in the dentate gyrus of the rat dorsal hippocampus.
Zuhayr Khan
Biotechnology Major
Principal Investigator/Faculty Mentor: Dr. Glenn Kageyama
Research: An Economical Protocol for Neuroanatomy Instructors and Researchers: Combining the Nissl and NADPH-diaphorase Protocols to Overcome their Individual Limitations
Background:
NADPHd histochemistry stains discrete populations of nitric oxide synthase producing interneurons, providing a Golgi-like appearance where the stained cells are shown in their entirety; including all of the dendrites, many axons, and the soma. However, it remains difficult to determine where these are located relative to other structures. In contrast, the Nissl staining technique allows for consistent labeling of the whole neuronal population but gives very limited information on neuronal morphology.
New Method:
By minimizing the exposure of stained and mounted NADPHd rat sections to lower grades of ethanol and the Nissl dye, we have developed a Nissl counterstaining protocol that enables one to quantitate the percent of blue, NADPHd stained cells or tissue in a given area, and determine their relation to surrounding red cell cytoarchitecture stained by the Neutral Red Nissl dye.
Robert D. Manuel
Biology Major
Faculty Mentor: Jamie Snyder
Research: Utilizing new methodology to screen Archaeal viral mutants
Abstract:
Viruses fill a special role in the ecology and evolution of all forms of life. The virus at the focus of this study, STIV, has developed into a model system for studying archaeal viral/host interactions. During infection of the host cell, Sulfolobus solfataricus, unique seven-sided pyramid structures are formed on the surface of the infected cell. As pyramid formation is solely dependent on one viral protein, a series of unbiased point mutations have been made throughout the coding sequence of the protein to learn more about it. The overall goal of this project is to screen these mutated C92 genes to identify amino acid residues required for replication. As the current methodology used to screen these viral mutants is both time consuming and only allows for the testing of one mutant at a time, the yeast-two-hybrid system and other such tests for screening viral mutants are being explored as possible avenues of research. These methodologies may have the potential to be a more time and cost-effective way of screening viral mutants. This will not only assist in elucidating the protein’s structure, but also will shed light on the STIV replication cycle as a whole.