A Merck Scholar does not have to be a Biology major or a Chemistry major. Biology and Chemistry majors, students who have not yet declared a major and those who have taken courses in these departments (but are majoring in other areas) are encouraged to apply. The overwhelming requirements are that a Merck Scholar must have an open and inquisitive mind, be interested in biochemistry, and want to explore scientific research.

The application process has three parts:

1. Read the list of research opportunities found below
2. Make an appointment to meet with the advisors who are working in a research area that interests you. It is appropriate to meet with more than one set of advisors to find a topic, approach, and advisor/scholar pairing that 'fits'.
3. Submit an application to Dr. Cindy Hauser before 5pm on March 23rd 2007. The application must contain a short proposal of intended research (one page max)and a description of how this internship fits in with your educational and career goals (one page max). (1.5 space, 12pt, Times font).

Current Projects:

Synthesis of 8-Azapurines as Anti-Viral Nucleoside Analogues. Student projects will use chemistry and biology together to analyze the molecular effects of novel compounds. 8-Azapurines with glycosidic-type groups on N9 of the purine ring have shown anti-viral activity. Unfortunately, 8-azapurines are difficult to synthesize. Through work of previous Merck/AAAS Scholars, we have developed a new method for accessing 8-azapurines. The key step involves a cycloaddition of an azide (1) with an enol ether (2) to form a triazole (3).1-2 Students involved in this project will learn techniques in organic synthesis and characterization as they synthesize compounds with suitable substituents on the azide and enol ether, so that the triazole may be converted into an 8-azapurine or similar nucleoside analogue.

Assays that measure viral replication and titer will monitor the anti-viral activity of products with promising structures. Thus, in this research students will perform a range of synthetic organic reactions, virus isolation and maintenance and cell culture techniques. Any of the prepared compounds showing biological activity will also allow Scholars to learn about substituent trends in structure-activity relationships. (Mentors E. Stevens & D. Wessner)

Identification of a CD4 Promoter Binding Protein with a CD4-Specific Binding Pattern.  Students will combine biology and chemistry techniques to identify and characterize transcription factors controlling thymocyte differentiation During T cell development in the thymus CD4-helper and CD8-killer T cells arise from a common thymocyte precursor. A complex pattern of CD4 regulation, primarily controlled by the activity of the CD4 silencer, allows CD4 gene expression in the developing CD4-helper T cells and, at the same time, silences CD4 expression in thymocytes that develop into CD8-killer T cells. However, CD4 silencer activity is not sufficient to determine CD-4 helper cell fate, indicating that there are additional differences in regulation of CD4 expression between CD4 and CD8 cells that may elucidate how “killer” vs. “helper” transcriptional regulatory programs are established and maintained. We have observed a CD4 promoter binding activity that is present in nuclear extracts of CD4, but not CD8 cells, which could explain the differences in CD4 gene expression in the two T cell types. Merck/AAAS Scholars will work to purify and identify this candidate transcription factor using a biochemical approach. Nuclear extracts from CD4 and CD8 T cells will be enriched for DNA-binding proteins by column chromatography, and oligo-precipitation will be performed using the wild type vs. mutant binding sequence from the CD4 promoter. The molecular weight of the unique protein(s) present in the CD4 nuclear extract will be identified by SDS-PAGE and silver staining. Through this work, Merck/AAAS Scholars will become proficient in cell culture, FACs analysis, oligo-precipitation, column chromatography and the analytical skills required to identify and purify a protein based on its chemical characteristics. (Mentors S. Sarafova & D. Blauch)

Investigation of the Teratogenic Effects of Pesticides During Zebrafish Development. Research performed by a previous Merck/AAAS Scholar studying the impact of malathion on neural development, will be expanded upon through a combination of molecular and chemical approaches . The organophosphorus pesticide malathion is frequently applied to bodies of water to reduce mosquito populations, even though pesticides can have teratogenic effects on the embryos of non-target aquatic organisms. Malathion exerts its biochemical influence by inhibiting acetylcholinesterase (AChE) at the neuromuscular junction. Previous studies found that zebrafish exposed to malathion experience decreased liver cell counts, abnormal ovaries, and skeletal deformities. Students found that sub-lethal doses of malathion caused compromised embryo development and fitness in wild-type embryos.3 Even short exposures to the pesticide compromised zebrafish embryonic development and dramatically reduced AChE enzymatic activity in vitro and in situ.4 Future experiments will use confocal microscopy to determine the pesticide’s effects on neuronal morphology and axon pathfinding in transgenic fish that expresses green fluorescent protein (GFP) in neurons (under the control of islet). In addition, malathion’s affects on zebrafish morphological development will be examined using GFP expressed in other organ systems (vasculature, gut, and heart). Mass spectroscopic analysis of tissue samples will allow analysis of malathion accumulation to complement the characterization of the morphological anomalies caused by the chemical. Students involved in the project will gain experience in zebrafish husbandry, micro-dissection, confocal and epifluorescence microscopy, digital image analysis, and mass spectroscopy.(Mentors B. Lom & C. Hauser)

Organic Aerosols and Ozone: Heterogeneous Chemistry and Affects on Lung Epithelial Cells. Atmospheric aerosols have come under close scrutiny in the last decade due to a correlation between aerosol concentration and premature mortality. The causal link is yet undetermined. Finding the link is further complicated by reactions with gas phase oxidants, like ozone, that occur as aerosols age in the atmosphere and by the complexity of the lung in which health-related responses occur. Merck/AAAS Scholars will approach this problem from three angles . First, atmospheric concentrations of ozone will be monitored using OGAWA passive air samplers and ion chromatographic analyses. Second, extending the work of two previous Merck/AAAS Scholars, an aerosol flow tube and FT-IR Spectroscopy are combined to investigate reactions times, intermediates and products formed in heterogeneous reactions between organic aerosols (unsaturated hydrocarbons, fatty acids and polycyclic aromatic hydrocarbons) and ozone. Finally, and extending the work of a third Scholar, a chamber has been built to expose polarized L2 cells (rat alveolae Type II) to ozone and organic aerosols. Determining the relative levels of necrosis, apoptosis and cytokine production in cells +/- exposure will aid in elucidating the causal link between the reactants and their health impacts. Through this work Scholars will become well acquainted with analytical and instrumental approaches including environmental sampling, ion chromatography, FT-IR spectroscopy, cell culture, ELISA and spectrophotometric analysis of enzymatic activity. May involve two scholars during some years. (Mentors C. Hauser & K. Bernd)