Article Figures & Data
Figures
- Figure 1.
Cortical astrocytes occupy nonoverlapping domains. A, Top-view reconstruction of EGFP-expressing cortical astrocytes from dnSNARE coronal brain sections. B, Histogram representing the volume distribution of EGFP labeling of astrocytes. Raw data were fit with three Gaussian curves with peaks at 22,906, 46,188, and 78,684 μm3 (n = 4 dnSNARE mice). C, Based on the analysis performed in B, structures with a volume value within 90% of the first Gaussian function are shown in green, representing single astrocytes. Structures with volumes equivalent to two and three astrocytes are shown in blue and violet, respectively. D, Top-view reconstruction of the EGFP-expressing astrocytes obtained in vivo from a dnSNARE-expressing animal. E, Histogram of astrocyte volume distribution shows three distinct peaks at 21,033, 36,713 and 72,664 (n = 3 dnSNARE animals). F, Using the same criteria and color code as in C, structures corresponding to single, two, and three astrocytes are shown.
- Figure 2.
One astrocyte enwraps several neuronal somata. A and B show individual optical sections to reveal the structure of astrocytes expressing EGFP within the dnSNARE mouse (green; left), the location of neurons immunolabeled with anti-NeuN (red; middle), and an overlay (right). Note that the astrocytes contain several holes, which correspond with the locations of neuronal somata. C1, Top-view reconstruction of a single astrocyte (green) and neurons (red). C2, The same cells shown in C1 are depicted in a top-view reconstruction with a threshold mask. Neurons within the astrocytic territory are red (yellow arrows). D, Distribution of the number of neuronal somata that contact one astrocyte. At least 50% of the surface area of a neuron had to make contact with the astrocyte to be considered as having sufficient interaction for inclusion in this analysis. E, F, A single confocal plane of an AAV-transduced astrocyte (green) contacting neuronal somata (red). G, Three-dimensional reconstruction of the astrocyte in E and F.
- Figure 3.
Single astrocytes enwrap different dendrites of the same neuron. A, Left, Top-view reconstruction showing a biocytin-filled layer 2/3 cortical neuron in a slice from a dnSNARE animal. A volume analysis, performed as in Figure 1, identifies regions of EGFP expression corresponding to one (right, green) or two (violet) astrocytes. B, Bar graph showing the distribution of the dendrite length covered by a single astrocyte. Data are obtained from 24 dendrites of four layer 2/3 cortical neurons from three different animals. C, Left, Two examples of biocytin-filled cortical neurons stained with Alexa-conjugated streptavidin. Right, Higher-magnification images allow the identification of single spines. D, Distribution of the linear density of spines measured in 105 dendrite segments from nine biocytin-filled cortical neurons.
- Figure 4.
Schematic representation of functional synaptic islands. A, Diagram showing three astrocytes. The holes are filled with neurons, one of which is shown to have its processes extending out to other astrocytes pointing to the potential of different neuronal compartments being modulated by different astrocytes. B, Diagram illustrating the concept of functional synaptic islands: a group of dendrites from several neurons are enwrapped by a single astrocyte. Synapses localized within the territory of this astrocyte have the potential to be modulated in a coordinated manner by gliotransmitter(s) released from this glial cell.
Additional Files
Supplemental Data
Files in this Data Supplement:
- supplemental material - Supplemental Legends
- supplemental material - Supplemental Figure 1
- supplemental material - Supplemental Figure 2
- supplemental material - Supplemental Figure 3
