Charles T. Anderson - US grants

An award is made to The Pennsylvania State University, University Park campus to purchase a super-resolution microscope that will enable the capture of images of plant and animal cells, as well as complex chemical samples, at the scale of single molecules. This microscope will reveal new insights into how living and chemical systems are organized and work. The project will also generate new image analysis tools for the scientific community. The microscope will enable interdisciplinary research training and enhance education through coursework and outreach to other Penn State campuses and other institutions. Integration of this microscope into a core microscopy facility will make it available to undergraduate, graduate and postdoctoral trainees, and regular imaging workshops will be offered by Penn State. New teaching modules for K-12 and undergraduate educators demonstrating the science of size and the potential of super-resolution microscopy will be developed. Access and training will be assured for underrepresented students through programs including the Summer Experience in the Eberly College of Science, McNair Scholars, Women in Science and Engineering Research, and Minority Undergraduate Research Experience. Public understanding of super-resolution microscopy and its advantages will be catalyzed by multiple outreach activities and venues, including The Franklin Institute (science museum) and Penn State's Ag Progress Days, which together will expose this cutting-edge imaging technology to tens of thousands of people. The discoveries enabled by this microscope will advance the study of plant and animal development, sustainable agriculture and energy production, and the chemical interactions that define our physical environment.

Super-resolution microscopy is leading to dramatic new research opportunities in the life sciences, and has emerging capabilities in chemistry and materials research. Penn State will advance our optical imaging-based research through the purchase of a super-resolution microscope with both Structured Illumination Microscopy (SIM) and Stochastic Optical Reconstruction Microscopy (STORM) capabilities. Both imaging modules are combined on a single microscope platform, and use high-magnification total internal reflection fluorescence (TIRF) objectives, an automated focus retention system, and an integrated multi-channel solid state laser launch. The ease of use of this commercial super-resolution microscope is a particularly appealing feature for equipment residing within Penn State's Huck Institutes of the Life Sciences Microscopy & Cytometry Facility, a multi-user core facility. Research and training with this microscope will focus on four main areas: (a) plant cell biology; (b) animal cell biology; (c) chemistry; and (d) advanced image processing and pattern recognition. Researchers in groups (a)-(c) will leverage the increased resolution offered by this system to push their research into hitherto unreachable areas of fine-scale biological processes and molecular interactions. In parallel, group (d) will collaborate with those generating super-resolution imaging data to advance our ability to recognize structures and patterns from molecular localization data. The combined SIM/STORM microscope will maximally benefit the largest number of researchers in the life and chemical sciences at Penn State by offering a high degree of flexibility for sample labeling and imaging. As an integral component of this project, faculty with research interests in advanced image analysis and pattern recognition will generate new algorithms for analyzing SIM and STORM imaging data that will be widely applicable to super-resolution microscopy and will be freely disseminated to the global scientific community.

This project seeks to determine how the carbohydrate-based cell walls of guard cells dynamically change shape to control stomatal pore size, thus allowing plants to control carbon dioxide (CO2) uptake and water loss. Stomata are small openings in the surfaces of plants that regulate the photosynthetic conversion of CO2 into plant biomass, which serves as a renewable source of food, materials, and bioenergy. A deeper understanding of cell wall structure, mechanics, and dynamics in stomatal guard cells will help identify plants that can more efficiently use water, a major limiting factor in global agricultural production. The computational image analysis and modeling tools that will be developed in this project will provide scientists with new ways of interpreting and understanding experimental data. Because stomatal guard cells are an amazing example of cellular engineering by plants and are accessible and observable by scientists of all ages, a learning module will be developed and deployed that allows 4th through 8th graders to observe stomatal dynamics first-hand and challenges them to construct and optimize functioning macro-scale models of stomatal guard cells, helping to inspire future scientists and engineers. This project will also train two PhD students and a research associate in interdisciplinary research skills that cross the boundaries of biology, computer and information science, and engineering.

In plants, stomatal guard cells function as dynamic gatekeepers that control CO2 and water flux to maintain homeostasis. To control transpiration and photosynthesis, stomatal development, morphology, and mechanics are tightly regulated. However, two large gaps exist in our knowledge of how stomata develop and function. First, stomatal pores form via controlled separation of sister guard cells, but how this is accomplished is unknown. Second, the walls of guard cells must be highly flexible to enable repeated stomatal opening and closing, but strong enough to withstand the enormous turgor pressure that drives their deformation. How guard cell walls are molecularly constructed to meet these competing requirements remains largely undefined. This project will analyze the molecular and mechanical requirements for stomatal pore formation, and the dynamic molecular architecture of guard cell walls that underlie their unique mechanical properties, using a complementary set of approaches including molecular genetics, high-resolution microscopy, and computational image analysis. The data and insights gained from these analyses will be used to construct computational mechanical models of guard cell walls that can be iteratively refined with new experimental results, ultimately resulting in the ability to predict guard cell dynamics across a range of species, wall compositions, and signaling inputs.

In plants, stomatal guard cells influence both photosynthesis and water transport and are thus essential for growth and efficient water use. However, our understanding of guard cell function at the cellular and molecular levels is limited. This project studies how guard cells dynamically expand and shrink to open and close stomatal pores, controlling the uptake of carbon dioxide and the release of oxygen and water by the plant. Understanding how guard cells function will aid in the development of resilient, high-yielding crops that can grow in hot, dry environments and more effectively remove carbon dioxide from the atmosphere. The image analysis and modeling tools created in this project will allow researchers to predict the behavior of a wide range of mechanical behaviors and responses by cells. This multidisciplinary project will train three PhD students as future leaders across the topics of cell biology, computational image analysis, and mechanical testing and modeling of biological systems, and will spread knowledge of guard cells and plant biology using learning modules and research experiences for K-12 and undergraduate students.

Despite decades of research interest, the molecular and biophysical mechanisms by which stomatal guard cells function remain incompletely understood. In particular, the roles of the cell wall and water flux in guard cells and neighboring cells in stomatal mechanics are not fully defined. This project combines molecular genetics, cell biology, advanced microscopy, computational image analysis, nanoindentation, and computational modeling to measure and model turgor pressure and wall mechanics in wild type and mutant stomatal complexes of the model plant Arabidopsis thaliana. These analyses will be used to examine the biomechanics of guard cells and the dynamic mechanical and functional relationships between guard cells and their neighboring cells. Another major goal of the project is to use super-resolution microscopy to develop a clear picture of the molecular composition and architecture of the guard cell wall, and to use these data to construct detailed, accurate, and experimentally testable finite element and multiscale, multiphysics models of stomatal guard cells. Together, this work will enable the prediction of stomatal dynamics across a range of species, wall compositions, stomatal geometries, and signaling inputs.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.