Laboratory Research. My scholarship focuses on understanding mechanisms of female sperm storage. Female sperm storage is a process consisting of sperm accumulation, retention and regulated release from specific regions of the female reproductive tract. This process is nearly ubiquitous among animals with internal fertilization, yet its mechanism(s) remains poorly understood. Developmental biologists are interested in female sperm storage because: 1) it is a critical step between gametogenesis and fertilization, two much better understood developmental processes, and 2) it involves cell (sperm) movement and fate – central foci of study in development. Those studying sexual selection are interested in female sperm storage because it is one arena for sperm competition (competition among the ejaculates of multiple males for access to eggs) and a ‘gauntlet’ for cryptic female choice (preferential use of a given male’s sperm for fertilizations). Sperm competition and cryptic female choice are processes shaping the evolution of animal behavior, morphology and physiology.
I use the well-established animal model Drosophila melanogaster (a.k.a. the fruit fly) to study mechanisms of female sperm storage because it provides a tractable system to understand the genetic basis of physiological mechanisms, but still to relate that understanding to the whole animal.
At Gustavus Adolphus, my research has consisted of a long-term project; a deficiency screen of the Drosophila genome for genes involved in female sperm storage and smaller-scale projects related to mechanisms of female sperm storage. To explore the second chromosome, my students and I screened 90 different Drosophila lines (i.e. distinct genetic strains), mated and transferred ~5400 individual female flies, and counted >1,080,000 offspring. After analyzing the results and identifying genes associated with a failure to normally store sperm, I am now using a bioinformatics approach to filter through the 1721 candidate genes by cross-referencing them with six related genetic/proteomic screens. Fortunately, eight genes identified as having potential effects on female sperm storage in my screen correlate with more general female reproductive function in four of the other data sets – which is tantalizingly suggestive that these genes are involved in female sperm storage. My future plans include examining sperm storage in mutant females of these eight genes to test the hypothesis that they do, indeed, affect female sperm storage. I am optimistic that these results can be published in a peer-review publication such as Genetics or Development. My smaller-scale research projects include an examination of the role of muscles on moving sperm into storage and female control over sperm use for fertilizations. These frequently involve dissecting and staining female reproductive tracts and using microscopy to count the number of sperm therein. A single sample can take as much as two hours to prepare and measure. It is not unusual to have 40 or more counts included in a single experiment and several experiments are included in a publication. Each paper that ends up being published reflects ~18 months of work from conceptualization to writing.
In my field, publications correlate with, but do not directly reflect investment in research activities. For every research paper I have published, I have conducted at least twice as many experiments that are not included in the manuscript. This is because of a documented bias towards the publication of positive results (experimental results demonstrating a relationship between variables or a difference among treatment groups) over negative results (no relationship or no difference) – despite the fact that negative results can be biologically informative. I plan to incorporate experiments with negative results into manuscripts, but they will need to be included with positive results in order to be appealing to editors and reviewers.
Presentations. I continue to present my results in scholarly fora. I have presented my work at regional and national meetings on an alternating year basis (3 presentations in 5 years) since arriving at Gustavus Adolphus and am continuing to work on publishing my work in reputable peer-reviewed journals. For example, my 2006 manuscript “Emergence of sperm from female storage sites has egg-influenced and egg-independent phases in Drosophila melanogaster” was published in Biological Letters, a publication of Britain’s Royal Society. My research is contributing to a larger body of understanding about reproduction in general and female sperm storage in particular. A second paper, with a student co-author (“Sick of Mating”) has been recently acceptaed for publication in FLY. I have drafts of two additional manuscripts whose experimental work is largely completed and only require some additional analysis and writing. Thus, I am committed to a continuing pattern of professional activities that includes making my scholarship accessible to scientific colleagues for review and for their own research.
Funding. I have applied for and received funding to support my research. At this time, the funds have been internal, a Presidential Faculty/Student Collaborative Grant (2005) and a Research, Scholarship and Creativity Grant (2007). Now that the second chromosome deficiency screen is completed and largely analyzed, I feel that I am in a good position to work on a grant for external funding.
Collaborations. My professional activities include collaborations with other biologists. I continue to enjoy a productive scientific relationship with Dr. Mariana Wolfner at Cornell University. We are currently collaborating on experiments examining the role(s) of female muscular contractions on sperm storage in Drosophila through the use of mutants with abnormal muscle function. I am also collaborating with Dr. Larry Harshman at the University of Nebraska to examine the sperm storage function of females with mutant forms of genes identified in genetic screens in both his laboratory as well as my own. At Gustavus Adolphus Dr. Sanjive Qazi, who specializes in bioinformatics, and I are collaborating to identify biological pathways among the candidate genes identified from my deficiency screen. Identifying these brings us one step closer to understanding mechanisms of female sperm storage. I also collaborate with undergraduates to better understand female reproduction. My receipt of a Presidential Faculty/Student Collaborative Grant (with Tanner Miest ’07 in 2005) as well as posters and publications with undergraduates (listed in my curriculum vitae) is further evidence of my commitment to collaborate.
Reviews. I participate in a larger community of scholars and have been solicited to review for several reputable, peer review journals (Journal of Insect Physiology, Genetics and BMC Developmental Biology). I have reviewed roughly one paper a year since coming to Gustavus. In addition, I was asked to review seven chapters of the third edition of Scott Freeman’s Biological Sciences, an introductory textbook for biology majors.
 Csada, R. D., P. C. James, et al. (1996). “The “file drawer problem” of non-significant results: does it apply to biological research?” Oikos 76(3): 591-593.
Sterling, T. D., W. L. Rosenbaum, et al. (1995). “Publication decisions revisited: the effect of the outcome of statistical tests on the decision to publish and vice versa.” The American Statistician 49(1): 108-112.