2000 Abstracts 

(In alphabetical order by author. Click on the link at the bottom of the abstract for full review of the article.)

Effects of Aphthona species and integrated management on leafy spurge and native plant communities of Mount Sentinel

Fellow- Cynthia Buckalew
Mentor- Marilyn Marler

Abstract

Euphorbia esula L., commonly known as leafy spurge, is an invasive weed that has taken over many different ecosystems in Montana including Mt. Sentinel.  It is a long-lived perennial plant, which spreads by both roots and seed, allowing it to easily out-compete and suffocate native plant species.  Many efforts have been made to control leafy spurge including the use of herbicides, grazing, mowing, reseeding, and biological control agents.  In the past management has only focused on eradicating the noxious weed, and neglected native plant responses.
This project addresses whether management goals are being met with the use of leafy spurge control methods.  The first portion of this study looks at how the use of Aphthona spp., flea beetles, affect native plant species along with leafy spurge.  The second portion looks at how mowing, grazing, herbicides, reseeding, and flea beetles affect native plant species when used alone and in combination.  These two portions will determine if management goals aid in native plant restoration along with leafy spurge eradication.
The significance of this study is to understand how native communities respond to weed management activities in concert with attempts to most efficiently stop the spread of leafy spurge and then kill the already established plants.  The fight against noxious weeds is only successful when native species are reestablished and this study will determine which control methods are most successful

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Factors Associated with Habitat Use by Timberline Sparrows (Spizella (Breweri) Taverneri) the Southern End of Their Range?

Fellow- Suzanne A. Cox
Mentor-  Dick Hutto

Abstract

Organisms that live at high elevations will be faced with a dramatically changing environment as climate change plays out over the coming decades.  Current efforts to provide a corridor of continuous habitat along the spine of the Rocky Mountains are encouraging but without an understanding of the habitat requirements of the organisms we are trying to protect, decisions concerning what areas to protect are made blind.  I investigated the habitat associations of Timberline Sparrows by comparing vegetation characteristics at used and unused sites in northwest Montana.  The results of univariate logistic regressions, multivariate logistic regressions and a PCA indicate several variables associated with Timberline Sparrows presence at a site.  The presence or absence of Timberlines was correctly predicted 100% of the time by proportions of fir, herbaceous ground cover, and spruce. Other variables that were identified by the analyses to be important included the average size of the tree patches on a site and the distance to the nearest shrub and the nearest tree.  Birds were found using taller trees than has been reported previously.

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The host associations and developmental plasticity of Nemoria darwiniata 

Fellow- Adam Ehmer
Mentor- Dr. Erick Greene

Abstract

No abstract available.

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Mutations in parC of Borrelia burgdorferi Confer Resistance to Fluoroquinolones

Fellow-Kendal M. Galbraith
Mentor- D. Scott Samuels

Abstract

We have isolated and characterized fluoroquinolone-resistant mutants of Borrelia burgdorferi.  Fluoroquinolones are antibiotics that target the A subunits of the type II topoisomerases, DNA gyrase and topoisomerase IV (Topo IV).  First-step mutants had up to 75-fold resistance to a fluoroquinolone.  The mutations were all found in the quinolone-resistance-determining region (QRDR) of parC, the gene encoding the A subunit of Topo IV, indicating that the primary target of fluoroquinolones in B. burgdorferi is Topo IV.

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Training dogs to distinguish between black bear (Ursus americanus) and grizzly bear (Ursus arctos) feces

Fellow- Aimee Hurt
Mentors-  Erick Greene, Barbara Davenport

Abstract

Three dogs were trained to select grizzly bear feces (scat) from black bear scat when presented together in a scent box. There were either four black bear scats and one grizzly bear scat, or all black bear scats in each presentation. Dogs successfully chose the grizzly sample at a far greater success rate than random. Upon subset analyses of detection rates, in which familiar scat obtained a higher hit rate than unfamiliar scat, suggestions were made for improving training protocols. This study suggests that dogs are capable of the fine level of distinction required for such delicate distinction, and properly trained dogs may be useful tools for professionals desiring a pre-lab litmus test of species identification.

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Chromium Induced Neoplasia Using p53, Gadd45, NF-kB, and AP-2 Response Elements As Models For Binding Affinity

Fellow-  Julia Michelle Kotler
Mentor- Dr. Kent Sugden

Abstract

Chromium is a known metal carcinogen that exists in the environment in two stable oxidation states.  These are the hexavalent Cr(VI) and trivalent Cr(III) forms.  Only chromium(VI) enters the cell and is considered a human carcinogen.  It enters through nonspecific anion transport pathways as chromate (CrO42-), which is iso-structural to both sulfate and phosphate and therefore enters readily.  The reduction of the less stable chromium(VI) to chromium (III) within the cell is thought to form site-specific oxidative damage to DNA and reactive oxygen species (ROS) generation.  Chromium(V) is thought to be a valence state responsible for direct oxidative damage to DNA in the reduction pathway.  A model Cr(V)-salen complex is used in these in vitro studies to determine direct responsibility and consequences of the chromium damage that may eventually lead to neoplastic transformation.  Chromium preferentially oxidizes the nucleic acid guanine and produces structural changes.  The identified oxidative products induced by chromium(V) are 8-oxo-dG, gaunidinohydantoin, and spiroaminodihydantoin.  These changes lead to G:T transversions as identified from primer extension assays.  To investigate how these new structures affect protein-DNA-binding interactions, preliminary data has been collected using the tumor suppressor protein p53 consensus oligonucleotide, several transcription factor binding sites, including NF-kappaB, AP-2, and SP-1.  The consensus p53 binding site located in the third intron of the gadd45 sequence was used because of its growth arrest and DNA damage responsibilities.  EMSA (Electrophoretic Mobility Shift Assays) were carried out using these consensus oligonucleotides, wild-type protein extracts, HeLa nuclear cell extracts, and recombinant proteins. These preliminary data will be used in the next step using altered consensus sequences with the known oxidative products formed by Cr(V) to test binding affinity.

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Effects of monovalent and divalent cations on HIV type 2 dimerization

Fellow- Marcela Majda
Mentor- Dr. J. Stephen Lodmell

Abstract

The HIV type 2 virus is a retrovirus which dimerizes near its 5’ untranslated region.  The monovalent and divalent cation conditions required for its dimerization were studied.  The divalent cations which were considered were: Mg++, Mn++, Ca++, Co++ and Cu++; whereas the monovalent cations which were studied were: K+, Li+, Na+, Cs+ and Tl+.  The results show that the HIV type 2 RNA dimerized fully under high salt conditions with the efficiency of dimerization depending on the presence of both divalent and monovalent cations.  The divalent cations all showed essentially the same proficiency of dimerization with only Cu++ showing a decrease in the amount of dimer produced.  A high concentration of monovalent cation also promoted dimerization in the HIV type 2.  The presence of magnesium in the gel promoted increased amounts of dimer in most of the conditions run.  A dependence on the pH of the dimerization buffer was also observed, with the pH of the buffer promoting dimerization even in the absence of monovalent and divalent cations.

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Cloning of an immunodominant antigen gene of Bartonella bacilliformis

Fellow-Kyle E. McFarley
Mentor- Dr. M.F. Minnick

Abstract

No Abstract provided

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Do Voles Select Dense Vegetation for Movement Pathways at the Microhabitat Level?

Fellow- Lucretia Olson
Mentor- Don Christian

 Abstract

The relationship between habitat use by voles (Rodentia: Microtus) and the density of vegetative cover was studied to determine if voles select forage areas at the microhabitat level.  Using live traps, I trapped, powdered, and released voles at 10 sites.  At each trap site I analyzed the type and height of the vegetation in the immediate area.  Using a black light, I followed the trails left by powdered voles through the vegetation.  I mapped the trails using a compass to ascertain the tortuosity, and visually checked the trails to determine obstruction of the movement path by vegetation.  I also checked vegetative obstruction on 4 random paths near the actual trail, to compare the cover on the trail with other nearby alternative pathways.  There was not a statistically significant difference between the amount of cover on a vole trail and the cover off to the sides of the trail when completely covered; there was a significant difference between on and off the trail when the path was completely open.  These results indicate that voles are selectively avoiding bare areas, while not choosing among dense patches at a fine microhabitat scale.

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Does diversity play a role in resistance to invasion by knapweed?

Fellow- Mo O’Mara
Mentor- Ragan Callaway

Abstract

Spotted knapweed (Centaurea maculosa) is recognized as one of the region’s most noxious invasive weeds by the federal government and the states of Montana, Washington, Idaho and Oregon. Other species of Centaurea are also causing widespread ecological and economic problems in other western states.  Spraying and the use of biocontrols have had either short-term, or very limited effects on knapweed.  When invasions occur, plant community and animal diversity is rapidly diminished, and soil water absorption ability is decreased resulting in soil run off and increased stream sedimentation.  Solutions to invasive species such as knapweed will come from knowing more about the ecological mechanisms that allow knapweed to competitively exclude other species.  A current theory states that community diversity, the number of species in a community, may play a significant role in enhancing the ability of natural plant communities to resist invasion by exotic species, but it is not clear how diversity, ipso facto, may perform such a function.  Other researchers have argued that particular species have attributes that confer resistance to communities.  My research explores the importance of diversity and that of particular species in experimentally constructed Palouse prairie plant communities in the field, subjected to experimental invasion of knapweed.  Preliminary results of this experiment show no correlation between community diversity and knapweed invasion; nor does it show a correlation between individual species and resistance to invasion.  It must be noted that the research season was during a drought-ridden spring and summer.  Evaluation of the response of the communities to knapweed, and the performance of knapweed in these communities, is ongoing and results will not be seen until the fall of 2001.

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Cellular Location of Ribosomal Protein L7/L12 in Neisseria gonorrhoeae

Fellow- Jeanne Quick
Mentor- Dr. Ralph Judd

Abstract

Neisseria gonorrhoeae is the causative bacteria of the sexually transmitted disease gonorrhea.  It is responsible for a range of diseases causing many problems including sterility if the disease remains undetected.  Understanding the mechanisms of protein synthesis of this bacteria is an important part of creating diagnostic assays or vaccines to prevent disease.  Finding the location of Neisseria gonorrhoeae ribosomal protein L7/L12 may lead to a possible diagnostic test or vaccine, in addition to gaining an understanding of the physiology of bacterial membranes.  The hypothesis to be investigated was that ribosomal protein L7/L12 is a surface-exposed protein of Neisseria gonorrhoeae.  The hypothesis was tested by isolating inner-, mixed- and outer-membranes, cytoplasm, and periplasm from the specific gonococcal strain MS11LOSA.  The isolates were run on SDS-PAGE gels and Western blots probed with anti-L7/L12 monoclonal antibodies AMGC-1 and BSGC-2.  Results showed L7/L12 to be located in the cytoplasm and the periplasm, but not in the membrane fractions.  Implications for further research include immunoelectronmicroscopy of the bacteria probed with the same antibodies.

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Characterizing the binding site of the Hbb protein from Borrelia burgdorferi

Fellow- Corbin M. Schwanke
Mentor- D. Scott Samuels

Abstract

Borrelia burgdorferi, a spirochete that is the causative agent of Lyme disease, is unusual in that its genome is composed of a linear chromosome and both linear and circular plasmids.  The bacterium contains the small DNA-binding protein Hbb.  This protein belongs to a class of proteins called accessory factors, which function in assembling higher-order nucleoprotein complexes, altering DNA topology, and affecting transcriptional regulation and other metabolic processes.  Hbb has been recently shown to bind DNA with sequence specificity.   We have shown that Hbb binds specifically to several promoter regions in the B. burgdorferi genome.  DNase I footprinting has been performed to determine the DNA binding site in the ospC promoter, the gac promoter, and the dnaA/dnaN intergenic region.  These preliminary data have been used to establish a consensus DNA binding sequence.

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Starvation-induced Mutations in Escherichia coli

Fellow- Colby Stoddard
Mentor- Dr. Barbara Wright

Abstract

Dr. Barbara Wright’s laboratory is investigating the effect of starvation on depression and mutation and the consequences to evolution.  Starving the cell for carbon results in a metabolic shift that can promote cell survival.  During this shift, genes capable of relieving the imposed stress become specifically targeted for depression and transcription.  During transcription there is an increased vulnerability to mutation due to the non-transcribed, single stranded DNA.  The increase in mutation observed is specific to the starvation-targeted operons and does not occur on a genome wide scale.  These facts are significant to evolution because genes are specifically targeted by environmental stress for an increase in mutation.  The mutations that occur are essential because they produce variants on which evolution depends to select the fittest.  This project investigates the relationship between increased transcription and mutation in the lac and mal operons.  This is accomplished by manipulating two genes, cya and crp, which are essential for derepression in this system.  We have found that in the absence of these genes, transcription and mutation are decreased.

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Characterization of the immune response in wild cougars infected with feline immunodeficiency virus (FIV)

Fellow- Jesse Thompson
Mentorr- Dr. Mary Poss

Abstract

Individuals infected with a viral pathogen will mount antibody responses to different viral epitopes.  It is known that in a retroviral infection, the virus changes rapidly during the course of infection and this change may be reflected in the humoral response of the host organism.  In this study, an immunoblot assay was developed to test serum samples from two geographically distant populations of wild cougars.  Since this is an ongoing project, samples collected from Yellowstone National Park and the Snowy Mountain Range in Wyoming will be analyzed by immunoblot assay and potential trends in age, gender, or geographic location will be evaluated.  Since sequential serum samples are available for some of these cougars, the hypothesis that an individual’s antibody response will change over time will be tested.

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Effects of Mutation on the Structure and Function of the HIV-1 Envelope Protein Transmembrane gp41 Subunit

Fellow- Amanda Wilhelm
Mentor- Dr. Jack Nunberg

Abstract

The spread of HIV-1 world-wide has grown to epidemic proportions.  Today, the virus is being studied extensively in hopes of finding a possible vaccine.  One such area showing great promise is the research being conducted on the envelope of the virus.  The envelope contains a transmembrane protein, gp41, which is non-covalently bound to the protein, gp120.  Glycoprotein 41 has been the focus of much study as it plays a key role in viral fusion to target cells.  It is believed that amino acid substitutions in the sequence of gp41 could prove to be effective vaccine agents.  If an envelope that looks similar to a natural, wild-type, virus, yet is non-functional, could be constructed, the antibodies an immune response would create against it would potentially be capable of neutralizing natural virus if the subject should come in contact with it.
In this study, four different mutations were inserted into the envelope to study the effects the mutation had on the biosynthesis, transport, expression, and function of the transmembrane gp41.  The results showed that three of the four mutations were non- functional.  Of the two mutations whose cell surfaces were analyzed, both had the proteins present on their surface, similar to the wild-type control.  These results show that the mutant gp41 envelope proteins that are non-functional yet still have the proteins present on the cell surface, similar to a wild-type viral envelope, are potential elements in the search for a vaccine.

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