Administrators and Staff
Permanent URI for this community
Browse
Browsing Administrators and Staff by Issue Date
Now showing 1 - 5 of 5
Results Per Page
Sort Options
Item The staphylococcal accessory regulator, SarA, is an RNA-binding protein that modulates the mRNA turnover properties of late-exponential and stationary phase Staphylococcus aureus cells(Frontiers in Cellular and Infection Microbiology, 2012-03) Anderson, Kelsi L., PhD Morrison, John M. Beenken, Karen E. Smeltzer, Mark S. Dunman, Paul M.The modulation of mRNA turnover is gaining recognition as a mechanism by which Staphylococcus aureus regulates gene expression, but the factors that orchestrate alterations in transcript degradation are poorly understood. In that regard, we previously found that 138 mRNA species, including transcripts coding for the virulence factors protein A (spa) and collagen-binding protein (cna), are stabilized in a sarA-dependent manner during exponential phase growth, suggesting that SarA directly or indirectly affects the RNA turnover properties of these transcripts. Herein, we expanded our characterization of the effects of sarA on mRNA turnover during late-exponential and stationary phases of growth. Results revealed that the locus affects the RNA degradation properties of cells during both growth phases. Further, using gel mobility shift assays and RIP-Chip, it was found that SarA protein is capable of binding mRNA species that it stabilizes both in vitro and within bacterial cells. Taken together, these results suggest that SarA post-transcriptionally regulates S. aureus gene expression in a manner that involves binding to and consequently altering the mRNA turnover properties of target transcripts.Item Risk factors for early childhood infection of human herpesvirus-8 in Zambian children: The role of early childhood feeding practices(American Association for Cancer Research, 2014-02) Crabtree, Kay L.; Wojcicki, Janet M.; Minhas, Veenu; Smith, David R.; Kankasa, Chipepo; Mitchell, Charles D.; Wood, CharlesBACKGROUND: Human herpesvirus-8 (HHV-8) infection in early childhood is common throughout sub-Saharan Africa with prevalence increasing throughout childhood. Specific routes of transmission have not been clearly delineated, though HHV-8 is present in high concentrations in saliva. METHODS: To understand the horizontal transmission of HHV-8 within households to children, we enrolled for cross-sectional analysis, 251 households including 254 children, age two and under, in Lusaka, Zambia. For all children, plasma was screened for HHV-8 and HIV type I (HIV-1) and health and behavioral questionnaires were completed. Multilevel logistic regression analysis was conducted to assess independent factors for HHV-8 infection in children. RESULTS: Risk factors for HHV-8 infection included increasing number of HHV-8-positive household members [OR = 2.5; 95% confidence interval (CI), 1.9-3.3; P < 0.01] and having a primary caregiver who tested the temperature of food with their tongue before feeding the child (OR = 2.4; 95% CI, 1.93-3.30; P =0.01). Breastfeeding was protective against infection with HHV-8 for children (OR= 0.3; 95% CI, 0.16-0.72; P < 0.01). CONCLUSIONS: These results indicate that exposure to HHV-8 in the household increases risk for early childhood infection, with specific feeding behaviors likely playing a role in transmission. IMPACT: Interventions to protect children from infection should emphasize the possibility of infection through sharing of foods.Item Active learning in the undergraduate classroom: A journal-club experience designed to accentuate course content(National Association of Biology Teachers, 2016) Anderson, Kelsi L.Students in the natural sciences should be prepared as undergraduates to read and apply concepts from the scientific literature. I describe a strategy that enforced the necessity to deliver high volumes of content while incorporating an active-learning technique. Students were assigned to read and discuss articles from the scientific literature that complemented content being delivered via traditional lecture. Students were encouraged to participate by coming to class prepared with written questions, and discussion was directed by instructor-prepared prompts. Students were assessed via low-stakes assignments based primarily on participation. This teaching method has proved effective, as verbally reported by past students who are currently enrolled in graduate programs. These students report feeling more prepared than their peers to discuss and learn from the scientific literature.Item Characterizing the Antibacterial Properties and Transcriptional Alternations Induced by Lemongrass Oil in Staphylococcus aureus(The Journal of Experimental Microbiology & Immunology+, 2017) Christensen, Collin J.; Anderson, Kelsi LEssential oils have risen in popularity as “all natural” alternatives used to treat a myriad of conditions. To begin to elucidate the antibacterial properties of essential oils, we tested the effectiveness of lemongrass oil (LGO), tea tree oil (TTO), and willow bark extract (WBE) against Staphylococcus aureus growth. To do so, a Methicillin-Resistant strain of Staphylococcus aureus (USA300) was exposed to each oil using disk diffusion assays. Of the oils, LGO had the greatest zone of inhibition. The Minimum Inhibitory Concentration (MIC) of both LGO and citral (the primary chemical component of LGO) was determined in macro-broth cultures; exposure to increased concentrations of each resulted in dramatic cell death as determined by cell growth assays. To begin to determine the molecular mechanisms underlying the observed antibacterial effects, we exposed cells to a sub-inhibitory concentration of citral and hybridized the RNA to Affymetrix GeneChips®. Transcripts differentially affected in citral- versus mocktreated cells represent virulence factors, hypothetical proteins, and intergenic regions. Taken together, these results demonstrate that LGO exhibits antibacterial properties against a highly pathogenic bacterial species that is exceedingly resistant to the currently available antibiotics.Item Association of household food- and drink-sharing practices with human herpesvirus 8 seroconversion in a cohort of Zambian children(Oxford University Press for the Infectious Diseases Society of America, 2017-10-17) Crabtree, Kay L.; Wood, Charles; Wojcicki, Janet M.; Minhas, Veenu; Kankasa, Chipepo; Mitchell, CharlesBackground: Human herpesvirus 8 (HHV-8) infection occurs in early childhood and is associated with human immunodeficiency virus type 1 (HIV-1) infection and risk for Kaposi sarcoma, but behaviors associated with HHV-8 transmission are not well described. Methods: We enrolled and followed a prospective cohort of 270 children and their household members to investigate risk factors for HHV-8 transmission in Lusaka, Zambia. Results: We report an incidence of 30.07 seroconversions per 100 child-years. Independent risk factors for HHV-8 incident infection included having a child who shared utensils with a primary caregiver (hazards ratio [HR], 2.33; 95% confidence interval [CI], 1.49-7.14), having an increasing number of HHV-8-infected household members (HR, 1.27; 95% CI, 1.09-2.79), and having >/=5 siblings/children in the household (HR, 2.24; 95% CI, 1.03-4.88). Playing with >5 children a day was protective against infection (HR, 0.54; 95% CI, .33-0.89), as was increasing child age (HR, 0.96; 95% CI, .93-.99). Conclusions: This is the first study to find a temporal association between limited child feeding behaviors and risk for HHV-8 infection. Child food- and drink-sharing behaviors should be included in efforts to minimize HHV-8 transmission, and households with a large number of siblings should receive additional counseling as childhood infections occur in the home context.