confocal microscopy

COCHLEAR SIGNALING MEDIATED BY HENSEN’S CELLS

PROJECT SUMMARY/ABSTRACT The organ of Corti has two types of auditory sensory cells (inner and outer hair cells) surrounded by nearly a dozen different types of supporting cells organized in a very meticulous pattern. Hair cells mediate the mechano-electrical transduction process of the organ of Corti and thus most cochlear auditory research has focused on these sensory cells. In contrast, much less is known about the different types of cochlear supporting cells, even though they likely impact hair cell function. Hensen’s cells are located laterally to the outer hair cell rows and appear to be the only cell type in the cochlear epithelium that expresses TRPA1 channels. These channels are widely known for their role as sensors of tissue damage and inflammation in nociceptive neurons. Not surprisingly, we recently found that Hensen’s cells are main sensors of tissue damage in the cochlear epithelium via the activation of TRPA1 channels (Velez-Ortega et al., Nat Commn, 2023). Additionally, our preliminary data also supports the role of Hensen’s cells in signaling pathways important for the proper innervation of the organ of Corti (aim 1), for the transmission of cochlear damage signals to the brain (aim 2), and for the regulation of hearing sensitivity after acoustic trauma (aim 3). Thus, here we will explore the hypothesis that TRPA1- mediated signaling pathways in the Hensen’s cells are required for the proper innervation and auditory function of the organ of Corti. In Aim 1 we will perform a detailed comparison of the morphology and synapses of afferent cochlear neurons of wild-type and Trpa1-/- mice at several developmental stages (using immunolabeling, confocal microscopy, STED microscopy, and electron microscopy) to assess the role of TRPA1 activity on the postnatal refinement of the cochlear innervation. Aim 2 will evaluate whether the afferent type II spiral ganglion neurons (SGN) can be activated downstream of TRPA1 channel gating in Hensen’s cells by testing responses of neonate and adult type II SGN to TRPA1 agonists (via live-cell time-lapse calcium imaging and patch clamp recordings of type II SGN dendrites). Aim 3 will test the impact of TRPA1 signaling in Hensen’s cells to the operating point of the cochlear transducer (via the recording of cochlear microphonics) and to cochlear tuning (via the recording of ABR tuning curves). This study is significant because it will contribute to our understanding of the cellular (Hensen’s cells plus type II SGN) and molecular (TRPA1 channels) mechanisms of the elusive cochlear nociceptive pathway. In addition, given that the loss of TRPA1 channels does not affect hearing thresholds in mice, we believe that undiagnosed deficits in TRPA1-dependent responses in the human population could represent a hidden susceptibility for cochlear damage after noise exposure or other insults.

Facilitating the Advancement of Research and Education for Undergraduate Students by Incorporating Laser Scanning Confocal Microscopy (FAREUS-LSCM)

PROJECT SUMMARY/ABSTRACT The University of Puerto Rico at Aguadilla (UPR-Aguadilla) requests funding to acquire a Nikon AX Galvo Confocal Laser Scanning Microscope (LSCM) with a TI2-E inverted platform and a four- laser configuration (405/488/561/640 nm) to establish transformative imaging capabilities at our resource-limited institution serving 96% Pell Grant recipients. This state-of-the-art instrument addresses a critical infrastructure gap, enabling high-resolution fluorescence imaging, live-cell microscopy, and quantitative analysis essential for competitive biomedical research and undergraduate education. The LSCM will directly support four active research projects spanning parasitology (monogenean host-specificity studies), plant pathology (coffee biocontrol development), environmental chemistry (metalloprotein biomarkers), and neuroscience (astrocyte dysfunction in diabetic epilepsy) while integrating into core laboratory courses including Immunology (BIOL 4009) and Undergraduate research courses (BIOL 3108 and QUIM 4999). Our multidisciplinary faculty, in partnership with the Neuroimaging and Electrophysiology Facility (NIEF) Excellence Imaging Center, offers expertise in confocal microscopy, encompassing advanced imaging and specialized sample preparation techniques. This collaboration ensures effective implementation of the technology, sustained technical support, and high-quality training programs that will enhance research productivity and broaden educational impact. The broad, long-term objective is to transform UPR-Aguadilla from a primarily teaching institution into a research-active campus capable of producing graduate-school-ready students equipped with cutting-edge technical skills. Access to advanced confocal microscopy will stimulate new research collaborations, enhance faculty productivity, and provide 30-40 students annually with hands-on experience in modern imaging technologies currently absent from our curriculum. The instrument will strengthen our partnership with the emerging Natural History Museum of Puerto Rico for specimen digitization and support comprehensive outreach programs targeting 25-50 high school students annually through "Seeing Science Up Close" workshops. Expected outcomes include 1- 2 peer-reviewed publications within three years, establishment of 1-2 new institutional collaborations, and measurable enhancement of biomedical research capacity. This investment will significantly advance STEM education and research opportunities at UPR-Aguadilla while expanding access to cutting-edge scientific instrumentation for students pursuing biomedical careers and contributing to the development of skilled researchers in the biomedical sciences.

Gap Junction Coupling between Photoreceptors

Simply put, the goal of my research is to describe the neuronal circuitry of the retina. The organization of the mammalian retina is certainly complex but it is not chaotic. Although there are many cell types, most adhere to a relatively constant morphology and they are distributed in non-random mosaics. Furthermore, each cell type ramifies at a characteristic depth in the retina and makes a stereotyped set of synaptic connections. In other words, these neurons form a series of local circuits across the retina. The next step is to identify the simplest and commonest of these repeating neural circuits. They are the building blocks of retinal function. If we think of it in this way, the retina is a fabulous model for the rest of the CNS. We are interested in identifying specific circuits and cell types that support the different functions of the retina. For example, there appear to be specific pathways for rod and cone mediated vision. Rods are used under low light conditions and rod circuitry is specialized for high sensitivity when photons are scarce (when you’re out camping, starlight). The hallmark of the rod-mediated system is monochromatic vision. In contrast, the cone circuits are specialized for high acuity and color vision under relatively bright or daylight conditions. Individual neurons may be filled with fluorescent dyes under visual control. This is achieved by impaling the cell with a glass microelectrode using a 3D micromanipulator. We are also interested in the diffusion of dye through coupled neuronal networks in the retina. The dye filled cells are also combined with antibody labeling to reveal neuronal connections and circuits. This triple-labeled material may be viewed and reconstructed in 3 dimensions by multi-channel confocal microscopy. We have our own confocal microscope facility in the department and timeslots are available to students in my lab.

SENPAI: SEgmentation of Neurons using PArtial derivatives Information. A tool for neuronal segmentation from confocal microscopy using K-means and topological information

The Wiener Deconvolution Tools: A novel software for deconvolving light sheet and confocal microscopy data