Snapshots in Neuroscience: Mossy fiber boutons

These images have been selected to showcase the art that neuroscience research can create.

As described by Dr. Marta Orlando and colleagues: “This image displays partial 3D reconstructions of mossy fiber boutons, which are unique synapses in the hippocampus. The presynaptic membrane is shown in turquoise, the postsynaptic membrane in green. Inside the presynaptic compartment, synaptic vesicles can be detected as small spherical structures (blue and red, respectively). The synapse on the left is from a wild-type mouse; the synapse on the right is from a mouse lacking the synaptic protein synapsin (synapsin knock-out). Synapsin regulates the clustering of synaptic vesicles and thereby also their availability for release.

“This image highlights some of the structural changes in mossy fiber synapses occurring upon the loss of all synapsin isoforms: Synapses from the knock-out model contain fewer but more dispersed vesicles than wild-type synapses. We found that these changes, together with an increase in active zone density, underlie disturbed presynaptic plasticity patterns in the knock-out model. Pronounced forms of presynaptic plasticity are a hallmark of mossy fiber synapses and the synapsin knock-out model enabled us to shed light on the underlying mechanisms.

“Synapses were partially reconstructed from serial images obtained with a transmission electron microscope operated at 80 kV and equipped with a digital camera. Mossy fiber synapses were imaged in chemically fixed hippocampal slices with a 20,000x magnification. Synaptic structures were manually segmented in each image. Stacks contained up to ten images of 70 nm thin serial sections.”

Partial reconstructions of hippocampal mossy fiber synapses from wildtype (left) and synapsin triple knock-out mice (right). Synapses from chemically fixed hippocampal slices were imaged on a transmission electron microscope with 20,000x magnification and were then reconstructed from stacks of 70 nm thin serial sections. Structures were manually assigned in each section. The presynaptic membrane is shown in turquoise, the postsynaptic membrane in green. Mitochondria are shown in middle blue. Synaptic vesicles are shown in blue for the wildtype synapse (left) and in red for the synapsin triple knock-out synapse (right). Image credit: Marta Orlando.

Read the full article:

The Lack of Synapsin Alters Presynaptic Plasticity at Hippocampal Mossy Fibers in Male Mice
Felicitas Bruentgens, Laura Moreno Velasquez, Alexander Stumpf, Daniel Parthier, Jörg Breustedt, Fabio Benfenati, Dragomir Milovanovic, Dietmar Schmitz, and Marta Orlando