Factors Contributing to the Success of NIH-Designated Underrepresented Minorities in Academic and Nonacademic Research Positions.

We report the outcomes of a survey of underrepresented minorities (URMs) in life science academic (e.g., faculty) and nonacademic (e.g., research-related) positions seeking to ascertain variables that contribute to their success (e.g., favorable or desired outcome). Given that they had positions in research careers, all respondents were presumed to be successful, and we sought to identify shared factors that were associated with this success. As in previous studies, respondents reported that undergraduate research opportunities, performing research in small- to medium-sized laboratories, and access to mentors throughout all stages of training were important factors for success in their careers. Surprisingly, analysis of the survey results suggests that a record of publications in high-impact factor journals was not essential for their success. There were fundamental differences in the experiences and needs of URMs in academic and nonacademic careers. For example, academic URMs ranked having mentorship as their first choice in order of importance compared with the nonacademic respondents, who ranked this category as their fifth selection. These findings suggest that taking diverse approaches toward these groups is critical for ensuring that all of the most creative minds have an equal opportunity to contribute to realizing our national research goals and diversified workforce.

Oxford-style debates in a microbiology course for majors: a method for delivering content and engaging critical thinking skills.

Developing scientific expertise in the classroom involves promoting higher-order cognitive skills as well as content mastery. Effective use of constructivism can facilitate these outcomes. However this is often difficult to accomplish when delivery of content is paramount. Utilizing many of the tenets of constructivist pedagogy, we have designed an Oxford-style debate assignment to be used in an introductory microbiology course. Two teams of students were assigned a debatable topic within microbiology. Over a five-week period students completed an informative web page consisting of three parts: background on the topic, data-based positions for each side of the argument, and a data-based persuasive argument to support their assigned position. This was followed by an in-class presentation and debate. Analysis of student performance on knowledge-based questions shows that students retain debate-derived content acquired primarily outside of lectures significantly better than content delivered during a normal lecture. Importantly, students who performed poorly on the lecture-derived questions did as well on debate-derived questions as other students. Students also performed well on questions requiring higher-order cognitive skills and in synthesizing data-driven arguments in support of a position during the debate. Student perceptions of their knowledge-base in areas covered by the debate and their skills in using scientific databases and analyzing primary literature showed a significant increase in pre- and postassignment comparisons. Our data demonstrate that an Oxford-style debate can be used effectively to deliver relevant content, increase higher-order cognitive skills, and increase self-efficacy in science-specific skills, all contributing to developing expertise in the field.

Assessment of individual and combined toxicities of four non-essential metals (As, Cd, Hg and Pb) in the microtox assay.

Although most researches with non-essential metals (NEMs) have been done with single or individual metals, in reality, organisms are often exposed to multiple contaminants at the same time through the air, food and water. In this study, we tested the toxicity of four NEMs, As, Cd, Pb, and Hg, individually and as a composite mixture using the microtox bioassay. This assay uses the reduction of bioluminescence of the bacterium Vibrio fischeri as a measure of toxicity. The concentrations of each chemical in the mixture were based on multiples of their maximum contaminant levels (MCLs) set by the U.S. EPA. The highest concentration of exposure was 20 times the MCL, which translated into 200, 100, 40 and 300 ppb for As, Cd, Hg and Pb, respectively. The ratio for the mixture from these concentrations was 10:5:2:15 for As, Cd, Hg and Pb, respectively. Among the individual metals tested, the ranking of toxicity was Hg>Pb>Cd>As based on the EC50 values of 109, 455, 508 and 768 ppb for Hg, Pb, Cd and As, respectively. The EC50 for the composite mixture was 495% MCL which translated into nominal concentrations of 49, 25, 10 and 74 ppb for As, Cd, Hg, and Pb, respectively. Overall, the EC50 value of each NEM within the mixture was lower than the EC50 of the individual chemical; an evidence of synergism for the mixture. The individual toxic units (TU) were 0.06, 0.05, 0.09, and 0.16 for As, Cd Hg, and Pb, respectively and the summed toxic unit (TU) was 0.37 (less than 1). This study provides needed scientific data necessary for carrying out complete risk assessment of As, Cd, Hg, and Pb mixtures of some priority compounds.

Cytotoxicity of dinitrotoluenes (2,4-dNT, 2,6-DNT ) to MCF-7 and MRC-5 cells.

DNTs are considered possibly carcinogenic to humans (Group 2B) because there is inadequate evidence in humans for carcinogenicity though there is sufficient evidence in experimental animals. In this study, MCF-7 (breast) and MRC-5 (lung) cells were exposed to a serial dilution of 2,4 and 2,6 DNTs (control, 1-500 ppm) in 96 well tissue culture plates. After various time intervals (24, 48, 72 and 96 hrs) the plates were washed, and 100microl fluorescein diacetate solution (10 microg/ml in PBS) was added column wise to each well, and incubated at 37 C for 30 - 60 min before reading the fluorescence with a spectrofluorometer at excitation and emission wavelengths of 485 and 538 nm respectively. Spectrofluorometeric readings were converted to percentages of cell survival. Regression analysis was conducted to determine the relationship between cell survival and exposed concentration. Linear equations derived from the regression analysis were used to calculate the LC50 values. Results indicated that 2,6 DNT was more toxic to breast cells; LC50 values were 445 and 292 ppm at 24 and 48 hours respectively compared to 2,4 DNT showing LC50 values of 570 and 407 ppm at 24 and 48 hours, respectively. No significant differences in toxicity existed between the two chemicals with regard to lung cells. Contrary to the above observation, 2,4 DNT was more toxic to breast cells; LC50 values were 407 and 238 ppm at 24 and 48 hours respectively compared to lung cells showing LC50 values of 527 and 402 ppm at 24 and 48 hours respectively. No significant difference existed for 2,6 DNT between the two cell lines. Lungs cells were more resistant to the two chemicals.

Promoter sequences of varicella-zoster virus glycoprotein I targeted by cellular transactivating factors Sp1 and USF determine virulence in skin and T cells in SCIDhu mice in vivo.

Varicella-zoster virus (VZV) glycoprotein I is dispensable in cell culture but necessary for infection of human skin and T cells in SCIDhu mice in vivo. The gI promoter contains an activating upstream sequence that binds the cellular transactivators specificity factor 1 (Sp1) and upstream stimulatory factor (USF) and an open reading frame 29 (ORF29)-responsive element (29RE), which mediates enhancement by ORF29 DNA binding protein of immediate-early 62 (IE62)-induced transcription. Recombinants, rOKAgI-Sp1 and rOKAgI-USF, with two base pair substitutions in Sp1 or USF sites, replicated like rOKA in vitro, but infectivity of rOKAgI-Sp1 was significantly impaired in skin and T cells in vivo. A double mutant, rOKAgI-Sp1/USF, did not replicate in skin but yielded low titers of infectious virus in T cells. The repaired protein, rOKAgI:rep-Sp1/USF, was as infectious as rOKA. Thus, disrupting gI promoter sites for cellular transactivators altered VZV virulence in vivo, with variable consequences related to the cellular factor and the host cell type. Mutations in the 29RE of the gI promoter were made by substituting each of four 10-bp blocks in this region with a 10-bp sequence, GATAACTACA, that was predicted to interfere with enhancer effects of the ORF29 protein. One of these mutants, which was designated rOKAgI-29RE-3, had diminished replication in skin and T cells, indicating that ORF29 protein-mediated enhancement of gI expression contributes to VZV virulence. Mutations within promoters of viral genes that are nonessential in vitro should allow construction of recombinant herpesviruses that have altered virulence in specific host cells in vivo and may be useful for designing herpesviral gene therapy vectors and attenuated viral vaccines.