Life Sciences Commons^™

The Regulation Of The Icsp Promoter Of Shigella Flexneri By The Virulence Factor Virb, Maria Castellanos, Dustin Harrison, Helen Wing

Undergraduate Research Opportunities Program (UROP)

Shigella flexneri is a pathogenic bacterium that causes severe dysentery in humans commonly known as shigellosis. Shigella encodes an outer membrane protease called IcsP. The regulation of icsP expression is under direct control of a transcriptional factor called VirB, which controls the expression of many virulence genes in Shigella. Previous work has shown through deletion analysis of the icsP promoter region that sequences as far as 1368 base pairs upstream of the transcription starting site are important for the regulation of the icsP gene by VirB. However, it is still unclear whether VirB activation requires sequences within the icsP promoter …

Microbial Nitrogen Cycling In Nevada Geothermal Springs, Mitchell G. Chaires, Jeremy A. Dodsworth, Brian P. Hedlund

Undergraduate Research Opportunities Program (UROP)

Hot spring habitats above maximum photosynthetic temperature (73 ºC) are not well understood with respect to nitrogen (N) cycling. Few predictions have been made, and even fewer measurements of in situ activities have been reported. Thermodynamic calculations based on in situ chemical and temperature measurements will be used to predict the occurrence of the specific N-cycling reactions. In addition, these measurements in two springs will aid in an attempt to cultivate ammonia oxidizing species.

Aerobic Respiration By Two Sulfate Reducing Magnetotactic Bacteria, Strains Rs-1 And Fh-1, Paul Howse, Sabrina Schubbe, Dennis A. Bazylinski

Undergraduate Research Opportunities Program (UROP)

Magnetotactic bacteria is the categorical name for a group of prokaryotes that biomineralize magnetosomes which are intracellular, membrane-bounded magnetic iron mineral crystals. The focus of this study is on two magnetiteproducing, magnetotactic sulfate-reducing bacteria (SRB), Desulfovibrio magneticus strain RS-1 and strain FH-1 which also belongs in the genus Desulfovibrio in the δ-Proteobacteria. SRB utilize sulfate as a terminal electron acceptor under anaerobic conditions reducing sulfate to sulfide. A large number of organic compounds as well as some inorganic compounds have been shown to provide electrons for sulfate reduction. Traditionally, because no SRB have been shown to convincingly grow with O2 …

Characterization Of The Omptin Protease, Ompt, In Escherichia Coli, Amanda Yates, Eun-Hae Kim, Helen Wing

Undergraduate Research Opportunities Program (UROP)

Omptins are outer membrane proteases found in gram negative bacteria that cause diseases in humans, such as pathogenic Escherichia coli, Shigella flexneri, Salmonella typhimurium, and Yersinia pestis. Bacterial species that express omptins cause diseases such as highly fatal plague and severe diarrhea and dysentery. The genes that encode these proteases are ompT, icsP, pgtE, and pla, respectively. These proteases are highly related in structure and share approximately 50% sequence identity. In S. flexneri, IcsP has been shown to cleave a key virulence determinant, IcsA (Egile et al., 1997). IcsA recruits host actin and allows for intracellular movement within host cells …

The Effects Of Host Physiological Conditions On The Expression Of Icsp In Shigella Flexneri, Karen Levy, Helen Wing

Undergraduate Research Opportunities Program (UROP)

Shigella flexneri is a gram-negative bacterium capable of causing diarrhea and dysentery known as shigellosis. It is estimated there are 167.4 million shigellosis episodes throughout the world each year causing 1.1 million deaths. Shigella invades cells in the lower intestine through an induced phagocytosis. Once in the cytoplasm, bacteria move from one cell to another using actin-based motility. The Shigella outer membrane protease IcsP regulates actin-based motility and cell-to-cell spread by cleaving the actin assembly protein IcsA from the bacterial cell surface. We hypothesize that IcsP may serve additional functions during infection. By examining which environmental signals trigger icsP expression, …

The Effect Of Cody On Stationary Phase Mutagenesis In Bacillus Subtilis, May Yared, Holly Martin, Eduardo A. Robleto, Ronald E. Yasbin

Undergraduate Research Opportunities Program (UROP)

We examine the notion that cells in conditions of stress accumulate mutation is in genes under selection via transcription processes. CodY is a global transcriptional regulator in many Gram positives, including soil and pathogenic microbes. In conditions of exponential growth and when branch chain amino acids and GTP are in abundance CodY acts as a transcriptional repressor of many metabolic operons. This transitional repression saves the cell energy and allows efficient use of resources. In conditions of starvation, CodY relieves repression of genes involved in acquisition of nutrients and degradation of carbon sources (genes under selection). Here, we compare the …

Potential Antimicrobial Properties Of The Cyanobacterium Microcoleus Vaginatus In Relationship To The Moss Bryum Argenteum, Crystal Erickson, Lloyd Stark

Undergraduate Research Opportunities Program (UROP)

Biological soil crusts play important ecological roles in arid desert regions. These crusts cycle nutrients, prevent wind/water erosion, and form the basis of food chains and soil formation in desert communities. Primary components of these structures include two desert moss species Bryum argenteum and Syntrichia caninervis, and Microcoleus vaginatus, a cyanobacterium. Our Phase I experiment strongly suggests that in an environment of intense light, a condition of stress to Syntrichia caninervis, there is an increase in shoot regeneration when cyanobacteria are present compared to when they are absent. Microcoleus is a highly motile species and our lab observations of fewer …

Denitrification In Great Basin Hot Springs, Austin Mcdonald, Brian P. Hedlund

Undergraduate Research Opportunities Program (UROP)

Hydrogen has been proposed to fuel primary production in the Aquificae dominated hot springs of Yellowstone National Park (Spear, et al. 2005), a finding the authors generalized to all hot springs. However, clone libraries derived from Great Basin springs contain few 16S ribosomal RNA (rRNA) gene sequences from Aquificae and many from unknown microorganisms. In the same springs, alternative electron donors rival the reducing power of hydrogen. This project will try to cultivate the uncharacterized microbes of two Great Basin springs and determine which electron donors they can use.

Nitrogen is key to life. In its reduced form, ammonia, it …

Kinetics Of Bacillus Anthracis And Bacillus Cereus Spore Germination In Soil And The C. Elegans Intestine, Maclean Hall, Ernesto Abel-Santos

Undergraduate Research Opportunities Program (UROP)

Bacillus anthracis and Bacillus cereus are both described as soil bacteria, but are almost exclusively found as spores within the soil. Soil is generally not a nutrient-rich environment and may lack the amino acids and nucleosides necessary for spore germination and vegetative reproduction. We aim to determine if soil alone can cause germination in these two species in order to produce vegetative cells that can reproduce. In addition, nematodes, decaying meat, maggots, and plant roots will be tested for their ability to cause germination in these species.

Microbial Ecology Of Keane Wonder Spring, Death Valley National Park, Alexander B. Michaud, Duane P. Moser

Undergraduate Research Opportunities Program (UROP)

This research is focused on developing a better understanding of he physiological and phylogenetic diversity as well as environmental abundance of bacteria of the genus: Shewanella in selected desert ecosystems. Prior research from this laboratory has revealed that these bacteria are very abundant in sulfurand organic-rich aquatics habitats. We have selected a number of habitats for detailed investigation (cultivation, molecular ecology and relevant environmental chemistry) including the Tropicana Wash, spring in Death Valley, the lower Virgin River and possibly Big Soda Lame, Nevada.

Genomic Foundations Of Carbon Fixation In Bacteria Living In Hot Springs, Rachel K. Skinner, Brian P. Hedlund, Jeremy A. Dodsworth

Undergraduate Research Opportunities Program (UROP)

Photosynthesis does not occur above 73°C, so organisms living above this temperature must obtain useable carbon by some other mechanism. It is generally assumed that carbon is fixed by thermophiles through the process of chemolithoautotrophy; however, primary production has never been demonstrated to occur in hot springs >73°C. We have shown that two organisms, Thermocrinis and Pyrobaculum, make up more than 90% of the cells in an 80°C Great Basin hot spring, Great Boiling Spring. We hypothesize that these organisms fix carbon in the hot spring via the reverse tricarboxylic acid (rTCA) cycle. To test this hypothesis we will: i) …