Keio University Human Biology-Microbiome-Quantum Research Center (WPI-Bio2Q) will hold a seminar as follows.

This is an event for faculty, students, and staff of Keio University. We sincerely look forward to your participation.

Abstract:

Neuronal synapses are fundamental units for information transmission, processing and storage in the nervous system. In vertebrates, disruptions in the neuronal connectivity of circuits leads to problems like cognitive impairment and neurodegenerative disorders.

During my PhD studies at the Max-Planck Institute of Biochemistry, we used cryogenic electron tomography (cryo-ET) to investigate such disruptions in the presynaptic terminal, with synaptosomes as a model, and suggested a structural model of proximal synaptic vesicle priming and release. Although synaptosomes are great models in studying the ultrastructure of neuronal synapses, the integrity of neuronal circuits is lost in such studies. This circuit integrity is fundamental for properly studying the brain. Therefore, our aim at the MRC – Laboratory of Molecular Biology is to explore the connectivity and molecular architecture of neuronal synapses in tissue biopsies, using in situ cryo-ET. Despite the extraordinary potential of cryo-ET, the inherent challenges of reliably milling lamellae from tissue biopsies exceeding ~50 µm in thickness limit the broader applicability of this method. Current approaches (lift-out, trimming using cryo-ultramicrotomy) require extensive manual labour, additional sample transfer, and specialized expertise.

To tackle these issues, we developed a largely automated, lift-out-less, high-throughput pipeline for the fabrication of high-quality lamellae from animal tissue biopsies (> 150 µm) using plasma focused ion beam milling (pFIB). Our FIB workflow opens a new window for ultrastructural analysis of tissue biopsies and constitutes the backbone of our lab’s work on neuronal circuits.