%0 Generic
%A Albariri, Areej
%C Heidelberg
%D 2020
%F heidok:27330
%R 10.11588/heidok.00027330
%T Golgi apparatus and Golgi outposts in neurons  studied by correlative microscopy
%U https://archiv.ub.uni-heidelberg.de/volltextserver/27330/
%X The Golgi apparatus is a highly dynamic organelle, which has many vital functions in  cellular mechanisms like lipid metabolism, protein secretion, intracellular signaling, and  regulation of cell division. First described in neurons, the ultrastructure and function of  this complex network is still not well delineated. Recent studies have shown this  secretory organelle also in dendrites of neurons, named Golgi outposts (GOs). To date,  these GOs have been analyzed mainly by light microscopy while their ultrastructural  appearance remained only poorly defined.  To study the morphology of GOs in dendrites and to examine if GOs show a  different ultrastructure to that of somatic Golgi apparatus, I established new applications  of correlative light and electron microscopy in cultured neurons and brain slices, which  combine fluorescence microscopy with the superior resolution of electron microscopy.  Photo-oxidation-based approaches allow for the direct ultra-structural visualization of  fluorescent markers in 3D, like genetically encoded green fluorescent proteins (GFPs).  However, this challenging methodology had to be adapted to detect Golgi enzymes in  neuronal cell cultures and brain tissue. Therefore, I first optimized the chemical fixation  conditions for cultured hippocampal neurons to approximate the morphologic quality of  high-pressure freeze fixation. Secondly, I enhanced sensitivity, reliability, and precision  of photo-oxidation procedures on neurons, which allowed to analyse the 3D  ultrastructure of GOs in dendrites of cultured neurons and mammalian brain slices.  Correlative 3D microscopy showed that GOs are smaller in volume and have  lower number of cisternae per stack compared to somatic Golgi apparatus of the same  cell. Further, the number of peri-Golgi vesicles around GOs appears to be less.  Additionally, while the stack polarity of somatic Golgi apparatus might switch along the  ribbon, GOs have strictly unidirectional polarity.  The technical achievements and enhanced sensitivity regarding correlative  microscopy of GFPs in cultured neurons and brain slices allow for further ultrastructural  investigations of GOs at different metabolic states to better understand their vital  functions.