Biology subjects

Kandel, E.

Publications and source records attributed to Kandel, E..

4 recordsLinked to original sources

bioRxiv2021

Fast 3D Clear: A Fast, Aqueous-Based, Reversible Three-Day Tissue Clearing Method for Adult and Embryonic Mouse Brain and Whole Body

To date, a variety of optical clearing methods have emerged that serve as powerful tools to study intact organs and neuronal circuits. Here we describe a newly developed, aqueous clearing protocol named "Fast 3D Clear", which relies on tetrahydrofuran (THF) for tissue delipidation, and iohexol (Histodenz) for clearing, such that tissues can be imaged under immersion oil in light sheet imaging systems. Fast 3D Clear requires three days to achieve high transparency of adult and embryonic mouse tissues, while maintaining their anatomical integrity, and preserving a vast array of transgenic and viral/dye fluorophores, such as GCaMP3/6, tdTomato, Fast Blue, and IRF670. A unique advantage of Fast 3D Clear is its complete reversibility and thus compatibility with tissue sectioning and immunohistochemistry. Fast 3D Clear can be easily and quickly applied to a wide range of biomedical studies, thereby greatly facilitating the acquisition of high-resolution, two - and three -dimensional images.

cell biology↗

bioRxiv2021

A multisensory circuit for gating intense aversive experiences

The ventral hippocampus (vHPC) is critical for both learned and innate fear, but how discrete projections control different types of fear is poorly understood. Here, we report a novel excitatory circuit from a subpopulation of the ventral hippocampus CA1 subfield (vCA1) to the inhibitory peri-paraventricular nucleus of the hypothalamus (pPVN) which then routes to the periaqueductal grey (PAG). We find that vCA1[->]pPVN projections modulate both learned and innate fear. Fiber photometric calcium recordings reveal that activity in vCA1[->]pPVN projections increases during the first moments of exposure to an unconditioned threat. Chemogenetic or optogenetic silencing of vCA1[->]pPVN cell bodies or vCA1[->]pPVN axon terminals in the pPVN enhances the initial magnitude of both active and passive unconditioned defensive responses, irrespective of the sensory modalities engaged by a particular innate threat. Moreover, silencing produces a dramatic impact on learned fear without affecting milder anxiety-like behaviors. We also show that vCA1[->]pPVN projections monosynaptically route to the PAG, a key brain region that orchestrates the fear response. Surprisingly, optogenetic silencing of vCA1 terminals in the pPVN titrates the level of c-Fos neural activity in the PAG differently for learned versus innate threats. Together, our results show how a novel vCA1[->]pPVN circuit modulates neuronal activity in the PAG to regulate both learned and innate fear. These findings have implications for how initial trauma processing may influence maladaptive defensive behaviors across fear and trauma-related disorders. One Sentence SummaryA multisensory gate for high intensity aversive experiences.

neuroscience↗

bioRxiv2021

3D Neuronal Mitochondrial Morphology in Axons, Dendrites, and Somata of the Aging Mouse Hippocampus

The brains ability to process complex informations relies on the constant supply of energy through aerobic respiration by mitochondria. Neurons contain three anatomically distinct compartments - the soma, dendrites, and projecting axons - which have different energetic and biochemical requirements, as well as different mitochondrial morphologies in cultured systems. Here we apply a quantitative three-dimensional electron microscopy approach to map mitochondrial network morphology and complexity in the mouse brain. We examine three neuronal sub-compartments - the soma, dendrites, myelinated axons - in the dentate gyrus and CA1 of the mouse hippocampus, two subregions with distinct principal cell types and functions. We also establish compartment-specific differences in mitochondrial morphology across these cell types between young and old mice, highlighting differences in age-related morphological recalibrations. Overall, these data define the nature of the neuronal mitochondrial network in the mouse hippocampus, providing a foundation to examine the role of mitochondrial morpho-function in the aging brain.

neuroscience↗

bioRxiv2020

The low complexity motif of cytoplasmic polyadenylation element binding protein 3 (CPEB3) is critical for the trafficking of its targets in neurons

Biomolecular condensates, membraneless organelles found throughout the cell, play critical roles in many aspects of cellular function. Ribonucleoprotein granules (RNPs), a type of biomolecular condensate found in neurons that are necessary for local protein synthesis and are involved in long-term potentiation (LTP). Several RNA-binding proteins present in RNPs are necessary for the synaptic plasticity involved in LTP and long-term memory. Most of these proteins possess low complexity motifs, allowing for increased promiscuity. We explore the role the low complexity motif plays for RNA binding protein cytoplasmic polyadenylation element binding protein 3 (CPEB3), a protein necessary for long-term memory persistence. We found that RNA binding and SUMOylation are necessary for CPEB3 localization to the P body, thereby having functional implications on translation. Here, we investigate the role of the low complexity motif of CPEB3 and find that it is necessary for P body localization and downstream targeting for local protein synthesis.

neuroscience↗