Rapid 3D enhanced resolution microscopy reveals the dynamics of cortical dendritic spinules

C. R. Zaccard, K. Myczek, M. D. Martin-de-Saavedra, P. Penzes*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Dendritic spinules are thin, membranous protrusions formed by neuronal dendritic spines that are not adequately resolved by diffraction-limited light microscopy. Hence, our understanding of spinules is inferred predominantly from fixed-tissue electron microscopy (EM). Super-resolution modalities have enabled live-cell nanoscopic imaging, but their utility for fast, time-lapse, volumetric imaging has been restricted. Herein, we utilized rapid structured illumination microscopy (SIM) and ‘enhanced resolution’ confocal microscopy to study spatiotemporal spinule dynamics in live cultured cortical pyramidal neurons. Spinules on mushroom spines typically recurred at the same topographical locations and most were short-lived, originating near simple post-synaptic densities (PSDs), while a subset was long-lived and elongated, emerging from complex PSDs. Ca2+ puncta within spinules synchronized with spine head transients and Ca2+ depletion drastically decreased spinule number. Moreover, we uncovered evidence of differential Ca2+-mediated regulation of short-lived and long-lived spinules. Thus, we identified unique spinule classes divergent in lifespan, dynamics, morphology, relationship to the PSD, and regulation. These data suggest distinct synaptic functions of spinule classes, informing future studies, while demonstrating a new application for enhanced resolution microscopy.

Original languageEnglish (US)
JournalUnknown Journal
DOIs
StatePublished - Apr 18 2019

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • Immunology and Microbiology(all)
  • Neuroscience(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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