Biology subjects

Kosmidis, S.

Publications and source records attributed to Kosmidis, S..

3 recordsLinked to original sources

bioRxiv2022

CyclinD2-mediated regulation of neurogenic output from the retinal ciliary margin is perturbed in albinism

In albinism, aberrations in the ipsi-/contralateral retinal ganglion cell (RGC) ratio compromise the functional integrity of the binocular circuit. We focus here on the mouse ciliary margin zone (CMZ), a neurogenic niche at the embryonic peripheral retina, to investigate developmental processes regulating RGC neurogenesis and identity acquisition. We found that the mouse ventral CMZ has the competence to generate predominantly ipsilaterally-projecting RGCs, but this competence is altered in the albino visual system due to CyclinD2 downregulation and disturbed temporal control of the cell cycle. Consequently, albino as well as CyclinD2-deficient pigmented mice exhibit a diminished ipsilateral retinogeniculate projection and compromised depth perception. Pharmacological stimulation of calcium channels in albino mice, known to upregulate CyclinD2 in other cell types, augmented CyclinD2-dependent neurogenesis of ipsilateral RGCs, and improved stereopsis. Together, these results implicate CMZ neurogenesis and its regulators as critical for the formation and function of the mammalian binocular circuit. HighlightsO_LIThe mouse ventral CMZ produces predominantly ipsilateral RGCs. C_LIO_LIIn the albino visual system, CyclinD2 downregulation leads to delayed G1/S transition toward mitotic exit of CMZ progenitors. C_LIO_LIPerturbations in the temporal control of cell cycle by CyclinD2 lead to reduced Zic2+ RGCs and consequently, a diminished ipsilateral retinogeniculate projection and compromised depth perception. C_LIO_LICalcium channel modulation during embryogenesis normalizes the levels of CyclinD2 and restores binocular vision in albino mice. C_LI

developmental biology↗

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

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↗