Our Hearing Adapts in Space

Synaptic Plasticity in the Ear
Our mission to Mars is driving a need to better understand the physiological impact on the human body. Deep space travel places unique challenges for humans. It is important that there is minimal impact on space travelers' senses. This includes hearing.

This study uses our Shank 1a Antibody to determine changes in the neuronal structure of the ear in microgravity.

Image: Verification of antibodies to CtBP2 and Shank1a. A and B: serial 14-µm cryosections were obtained from a postnatal day 71 (P71) mouse utricle, and maximum-intensity projections are shown. Hair cell (hc) and support cell (sc) nuclei are illuminated by the DAPI stain (blue). Numerous closely associated CtBP2-and Shank1a-positive puncta can be observed in the positive immunostained section represented in A (block arrowheads). The CtBP2-positive puncta highlighted by the flared arrowhead in A may represent an undocked synaptic ribbon. No primary antibodies were included in the processing represented in the micrograph in B. The scale bar in B represents 5 µm and also applies to A. C and D: maximum-intensity projection micrographs from right and left whole mount utricles from a P65 mouse. Importantly, fixative administration into the temporal bones yielding the specimens represented in C and D was delayed 7 min to replicate the conditions associated with specimens derived from the microgravity and control specimens. The positive-immunostained specimen of the pair is shown in C, where numerous closely associated CtBP2-positive and Shank1a-positive puncta can be observed. Though faint, CtBP2-immunostained nuclei are highlighted by the flared arrowheads. The micrograph in D illustrates the results of withholding primary antibodies from the processing. Immunolabeled puncta are not observed. The scale bar in D represents 5 µm and also applies to C. https://www.physiology.org/doi/full/10.1152/jn.00240.2016 

These results demonstrate that structural plasticity was topographically localized to the utricular region that encodes very low frequency and static changes in linear acceleration, and illuminates the remarkable capabilities of utricular hair cells for synaptic plasticity in adapting to novel gravitational environments.

Staining Tissue From Space Mice

Our Synaptic Marker is Used to Compare Earth vs Space Samples
Exposure to the microgravity conditions of spaceflight alleviates the load normally imposed by the Earth’s gravitational field upon the inner ear utricular epithelia. Previous ultrastructural investigations showed that spaceflight induced an increase in synapse density within hair cells of the rat utricle. However, the utricle exhibits broad physiologic heterogeneity across different epithelial regions, and it is unknown whether capabilities for synaptic plasticity generalize to hair cells across its topography. To achieve systematic and broader sampling of the epithelium than previously conducted we used immunohistochemistry and volumetric image analyses to quantify synapse distributions across representative utricular regions in specimens from mice exposed to spaceflight (a 15-day mission of the space shuttle Discovery). These measures were compared to similarly-sampled Earth-bound controls. Following paraformaldehyde fixation and microdissection, immunohistochemistry was performed on intact specimens to label presynaptic ribbons (anti-CtBP2) and postsynaptic receptor complexes (anti-Shank1A) DOI: 10.1152/jn.00240.2016.

Mature vestibular hair cells retain capabilities for structural plasticity manifested through modulation of synapse density. Investigations are ongoing that are testing the hypothesis that synapse density increases may result from exposure to centrifugation-induced hypergravity, which would provide the foundation for future research into the molecular mechanisms through which these modifications are induced. This research will provide insight and strategies for inner ear rehabilitation through the induction of synapse density increases in conditions of vestibular paresis.

Maybe zero gravity will play a role in therapies for hearing loss?

Focus on Vision Systems Research

New Reagents, Publications and Data

We are intensifying our focus on Vision System Research with the addition of new antibodies. We are offering 50 USD off. They include: PSD-95/SAP90, Rhodopsin (A531), Rhodopsin (B630) and select Calcium (Ca2+) Signaling-Binding antibodies.

Image: Rhodopsin staining of pig retinal sections (green) and counter-stained with NF-M (red) and DNA (blue). Rhodopsin is most abundant in the outer segments of retina (OS), NF-M is abundant in the optic nerve fiber layer (ONFL), but seen in processes and neurons in other regions also. Other layers are pigmented epithelium (PE), outer and inner nuclear layers (ONL, INL), outer and inner plexiform layers (OPL, IPL) and ganglion cell layer (GCL). Inset: Bovine retinal extracts blotted with rhodopsin. Protocols on data-sheet.
Our ability to effectively serve researchers is confirmed by the growing parade of publications. I would like to highlight a recent publication by Dr. Sal Salvatore and his colleagues. It features use of our Shank 1a antibody. They are the first to show Shank 1 expression in the mammalian retina revealing Shank 1 immunoreactivity within both synaptic layers of the retina: Salvatore L. Stella Jr, Alejandro Vila, Albert Y. Hung, Michael E. Rome, Uyenchi Huynh, Morgan Sheng, Hans-Juergen Kreienkamp, Nicholas C. Brecha. Association of Shank 1A Scaffolding Protein with Cone Photoreceptor Terminals in the Mammalian Retina. PLoS ONE 7(9): e43463. doi:10.1371/journal.pone.0043463.

Images: Shank 1A immunoreactivity is in both the inner plexiform layer (IPL) and outer plexiform layer (OPL) of the mouse YFP-16 line retina. A–C: A. Image of a retinal section immunostained for Shank 1A. B. Mouse YFP-16 line vertical retinal section. C. Shank 1A (red) immunolabeling and YFP (yellow). Shank1A expression is restricted to the OPL and IPL. A regular pattern of Shank 1A immunolabeling appears in the OPL, which is indicative of cone photoreceptor terminals. D–E: High magnification zoom of the OPL demonstrates that Shank 1A puncta (red) are distal to the dendrite tips (yellow) of YFP labeled cone bipolar cells, suggesting that Shank 1A is expressed presynaptic to the YFP cone bipolar cell dendrite. G–L: High magnification zoom of the IPL demonstrates that Shank 1A puncta are likely expressed postsynaptically to bipolar cell terminals. G. Shank 1A immunoreactive puncta. H. YFP labeled neurons and processes within the IPL region. I. PKCα labeled rod bipolar cell axons and terminals. J. Combined Shank 1A (red) and PKCα (blue) immunolabeling illustrate that shank 1A puncta are postsynaptic to rod bipolar cell terminals in the IPL. K. Combined Shank 1A (red) immunolabeling and YFP (yellow) in the IPL demonstrate that Shank 1A puncta are postsynaptic to cone bipolar cell terminals in the IPL. L. Combined triple fluorescent image of Shank 1A (red), PKCα (blue), and YFP (yellow) in the IPL. OPL = outer plexiform layer, INL = inner nuclear layer, IPL = inner plexiform layer, and GCL = ganglion cell layer. Scale bars = 10 µm. doi:10.1371/journal.pone.0043463.g001

More Pubs
Diego C. Fernandez, Laura A. Pasquini, Damián Dorfman, Hernán J. Aldana Marcos, Ruth E. Rosenstein. Early Distal Axonopathy of the Visual Pathway in Experimental Diabetes. doi:10.1016/j.ajpath.2011.09.018

...a goat polyclonal anti–platelet-derived growth factor receptor-α (PDGFR-α) antibody (1:100; Neuromics, Edina, MN)
Raoul Torero Ibad, Jinguen Rheey, Sarah Mrejen, Valérie Forster, Serge Picaud, Alain Prochiantz, and Kenneth L. Moya. Otx2 Promotes the Survival of Damaged Adult Retinal Ganglion Cells and Protects against Excitotoxic Loss of Visual Acuity In Vivo. The Journal of Neuroscience, 6 April 2011, 31(14): 5495-5503; doi: 10.1523/​JNEUROSCI.0187-11.2011...For antibody neutralization experiments, anti-Otx2 antibody (Neuromics) was dialyzed against PBS, and then Otx2 (25 ng in 500 mul) was incubated with anti-Otx2 (0.5 mug) in culture medium at 37C...

Hoon Shim, Chih-Ting Wang, Yen-Lin Chen, Viet Q. Chau, Kevin G. Fu, Jianqi Yang, A. Rory McQuiston, Rory A. Fisher, and Ching-Kang Chen. Defective Retinal Depolarizing Bipolar Cells (DBCs) in Regulators of G-protein Signaling (RGS) 7 and 11 Double Null Mice. JBC Papers in Press. Published on February 27, 2012 as Manuscript M112.345751. The latest version is at http://www.jbc.org/cgi/doi/10.1074/jbc.M112.345751...Animals were sacrificed by CO2 inhalation and the eyeballs were immediately enucleated. After removal of cornea and lens the resulting eyecups were immersionfixed in 4% paraformaldehyde in 1X PBS at room temperature for 15 minutes. This short fixation time ensured good mGluR6 and Gb5 signals at the OPL. After cryoprotection in 30% sucrose in 1X PBS, the eyecups were embedded in TBS (Richard Allan Scientific, Kalamazoo, MI), sectioned at 20μm thickness, and stained...

I will keep you posted on progress.