Biology Honors Thesis Abstracts

Meagan Dagenais (Natalie Stassen), 2004

Coprinus Cinereus: Exploring the Mysteries of Meiosis

Meiosis is a characteristic of most eukaryotes and is essential for the survival and variation of genes passed on to future generations. The objective of this research project was to create and identify new meiotic mutants of Coprinus cinereus. By using Restriction Enzyme Medicated Integration (REMI), transformants can be created through the insertion of a plasmid carrying a marker gene, hygromycin resistance. Although this research project is still in the REMI transformation stage, continued research will lead to the identification of mutants by the lack of spore production. This disruption in the meiosis process would be identified in white fruiting mushrooms. There are estimated to be hundreds of meiotic genes, but only a handful has been identified so far. By identifying the genes responsible for meiosis and their functions, a door to the mysteries of meiosis and its evolution could potentially be unlocked.

Bradley Dunstan (Howard Thomas), 2013

Parasitic Arthropods on Bats of Colima, Mexico

Most parasitic arthropods spend only a portion of their life cycle on a single host. Whereas, some such as lice (Insecta, Anoplura and Mallophaga) spend most of their life on a particular host others such as chiggers (Acari, Trombiculidae) and fleas (Insecta, Siphonaptera) are found on a vertebrate host for a much shorter time. Arthropods of non-volant (flying) mammal hosts have the ability to leave one host and either infest another or re-infest the same host. Such mobility, within the life-cycle allows the arthropod the ability to complete non-parasitic portions of its life cycle, population dispersal, and infest new hosts. The biology of the parasitic arthropods on the outside surface of bats is unique as well as poorly understood. The volant nature of bats introduces barriers to successful exploitation by a parasitic arthropod. Paramount among these barriers is decreased likelihood of the arthropod reaching the ground?to detach from the host to complete life cycles, disperse or infestation of new hosts. Bat arthropod parasites, have therefore, evolved unique life cycles and hold-fast structures. As a reflection of these adaptations there is a high degree of host and host-site specificity by some arthropod parasites and bat hosts (ter Hofstede et al. 2004). There are two families of flies (Order Diptera) and a single family of mite (Order Acari) that are adapted to parasitism on bats. They are Streblidae and Nycteribiidae for the former and Spinturnicidae for the later. The Mexican state of Colima contains a bat diverse bat fauna (53 species, 27 genera, and 7 families). Despite this diversity of bat hosts little is known regarding the arthropod parasites found on them. The arthropod parasites of many of the Colima bats have been reported elsewhere: Venezuela (Guerrero 1993, 1994a, 1994b, 1995, 1998), Trinidad, BWI (Jobling 1949), Brazil (Linhares and Komeno 2000), Panama (Overal 1980, Wenzel 1976, Wenzel and Tipton 1966, and Wenzel et al. 1966). This abstract presents a listing of the parasitic arthropods found on a total of eighty-one bats of the following taxa: Artibeus intermedius (n=9), A. jamaicensis (n=8), A. phaeotis (n=3), A. toltecus (n=7), Balantiopteryx plicata (n=2), Desmodus rotundus (n=7), Glossophaga sp. (n=23), Micronycteris megalotis (n=5), Mormoops sp. (n=1), Pteronotus davyi (n=1), P. personatus (n=1), and Sturnira sp (n=12). These bats were collected at thirteen locations in Colima. Bats were euthanized, prepared as museum voucher specimens and deposited at the University of Oklahoma. Parasitic arthropods were collected using a combination of brushing and visual removal from the host using a dissecting microscope. Collected arthropods were stored in a 70% isopropyl alcohol solution and later cleared in a 1-2% potassium hydroxide solution and then placed on microscope slides using Euparol mounting medium. Arthropods were identified to the most taxonomically exclusive category possible. Identification of parasitic flies of the families Nycteribiidae and Streblidae were provided by Dr. Carl W. Dick of Western Kentucky University. All records reported in this study represent new locality records since no previous work has been done on bat parasitic arthropods from Colima. The student will look at the arthropods that have been collected and mounted and attempt to identify them.

Nicholas Gulbrandsen (Thomas Schoenfeld), 2013

The Chemistry of Olfaction

The airflow rate through the nostrils during inspiration is unequal due to nasal turbinate swelling greater in one nasal cavity than the other. Despite the asymmetry, the detection of odorants with each nostril is equal. There is evidence with odorants of high water solubility (sorptiveness), that this occurs because sniff duration is increased when sniffing through the lower flow rate nostril. However, it is unclear whether this trend applies generally to odorants varying more broadly in solubility. To investigate this further, we presented subjects with odorant detection tests, consisting of odorants broadly different in terms of water solubility, while sniffing parameters (airflow rate and duration) were monitored via spirometery. Detection with each nostril was recorded and keyed to the native birhinal asymmetry in airflow. This will test the hypothesis that odorant detection is optimized when variation in sorptiveness, and hence inspiratory transit, is matched with compensatory changes in sniffing.

Alexander Munding (Michael Nosek), 2013

Studies of Mitochondrial DNA Heteroplasmy in HepG2 (Hepatocarcinoma) Cells

Kearns-Sayre Syndrome (KSS) is a rare neuromuscular disorder that usually has an early onset before the age of 20 years. The most common form of KSS is characterized by a 4,977 bp deletion within the mitochondrial DNA. In?my work so far I have tried to induce this common deletion mutation within the Hepatocarcinoma cell line; more commonly known as HepG2 cells. I treated the cells with low concentrations of hydrogen peroxide to induce this mutation through oxidative damage. This was undertaken by splitting a confluent 25 cm3 flask of HepG2 cells into two 24 well plates. The cells were treated with concentrations of hydrogen peroxide from 0.3 % to 0.45% in 0.5% increments. One further step that has recently been undertaken is to force some of the cells to use their mitochondria through aerobic respiration using non-glucose media. The other half of treated cells are still contained in normal media. After treatment the half of the cells were taken for mtDNA extraction and PCR and the others were plated for further growth. The cells treated with the higher concentrations of hydrogen peroxide showed definite morphological changes and continuation of growth while other cells underwent apoptosis. The live cells were tested for the deletion mutation using polymerase chain reaction (PCR) but preliminary tests have not demonstrated the presence of the deletion mutation. Further repetitions of the experiment need to be undertaken to test if the KSS deletion can be induced by hydrogen peroxide. The goal of these experiments is to develop a reproducible method for inducing the mutation to further study factors that affect the amplification of the deletion mutation in these cells.

Daniel Savukoski (Michael Brodsky), 2004

The Identification and Mapping of CKOF1, A Novel DNA Damage Checkpoint Gene in Drosophilia Melanogaster

Signal transduction pathways known as cell cycle checkpoints respond to DNA damage by promoting both cell cycle arrest and DNA repair. To analyze these processes, a group of 12,000 mutant, yet viable, strains of Drosophila melanogaster were previously made (Zucker et al. San Diego CA) and screened for mutagen sensitivity (MUS) (Hawley et al. Davis, CA). Out of those 12,000 strains, 41 new MUS strains were isolated. We have used a cell cycle arrest assay to screen those MUS strains and have identified ckof1, a novel checkpoint mutant that blocks the early stages of DNA damage induced cell cycle arrest. Initial analysis of ckof1 individuals indicated a recessive mutation within a novel gene on Drosophila’s third chromosome. Further analysis using recombination and deficiency mapping has mapped ckof1 to the chromosomal interval of 64B13-64D3, a region that contains about 88 genes. In the future, the goal is to continue narrowing down the region of interest and to ultimately identify which gene is disrupted in ckof1 individuals.

Gimena Surarez (Howard Thomas), 2010

Patterns of Infestation by Skrjabingylus Nasicola in Mustela Vision and Mustela Erminea

Skrjabingylus nasicola is a parasitic nematode that infests the nasal cavities of mink (Mustela vison) and ermine (Mustela erminea). This infestation causes damage to the skulls of mink and ermine including discoloration, swelling, and perforation. This study was conducted to examine the role that age, gender, and host species play in the prevalence and progression of infestation by S. nasicola. Only a few scientific publications have dealt with the dynamics of this parasite host relationship. Most published articles dealt with a simple statement of prevalence in a host population. There has been no study of the type and extent of damage to the skull of the host. The skulls examined for this study were from the collection of the Museum of Comparative Zoology (MCZ), Harvard University, Massachusetts. The skulls were examined for cranial damages related to infection from S. nasicola. This study categorized and quantified these damages. Comparison of infestation rates were made between age and gender groups within species and between species. In Mustela vison, the frequencies of discoloration, swelling, and perforation were higher in juveniles than adults. The only age related difference in Mustela erminea was seen in higher perforation rates in adults. The swelling and perforation rates were higher in male than female mink. The only gender-related difference in ermine was found with higher perforation rates in males. The discoloration, swelling, and perforation rates were higher in ermine than in mink. Age, gender, and host species appear to affect the infestation rates of S. nasicola.