Biochemical controls: making operational synapses (Introduction)

by David Turell , Thursday, October 12, 2023, 21:35 (198 days ago) @ David Turell

New research:

https://medicalxpress.com/news/2023-10-mechanism-decoded-synapses.html

"Synapses are points of contact between axonal nerve terminals (the pre-synapse) and post-synaptic neurons. At these synapses, the electrical impulse is converted into chemical messengers that are received and sensed by the post-synapses of the neighboring neuron. The messengers are released from special membrane sacs called synaptic vesicles.

"As well as transmitting information, synapses can also store information. While the structure and function of synapses are comparably well understood, little is known about how they are formed.

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"Synaptic vesicles are the membrane vesicles that contain messengers and are stored at each synapse to convert electrical signals into chemical signals. Together with scaffolding proteins that tell synaptic vesicles where the synapse is, and calcium channels that chemically translate the electrical signal, these vesicles form the central elements of the pre-synapse.

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"The synaptic vesicle proteins and the proteins of the so-called 'active zone' and likely also the adhesion proteins that hold synapses together, share the same bus," states research group leader Professor Dr. Volker Haucke, describing the surprising finding. "It was highly controversial. And yet our data in human neurons in culture seem quite clear."

"But how exactly do the proteins get to the site of synapse formation? In their study, the researchers were able to show, for one thing, that a machinery of motor proteins powers axonal transport. According to their findings, the main driver is a kinesin known as KIF1A. This motor protein is best known for its association with neurological disorders in the peripheral nervous system and the brain.

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"Moreover, the researchers were also able to determine the cell-biological identity of the axonal carriers. That led to another surprise: While the vast majority of secretory vesicles originate from the so-called Golgi apparatus, the axonal transport vesicles do not contain Golgi markers, but share markers with the endolysosomal system, which typically is involved in the degradation of defective proteins in non-neuronal cells.

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"[b']Our work suggests that neurons have invented a new kind of organelle, a transport organelle that may be unique to neurons,[/b]" explains Dr. Sila Rizalar, postdoctoral fellow at the FMP and lead author of the study. "This was as little known as the shared transport pathway.'" (my bold)

Comment: as usual I have presented irreducibly complex newly found structures in neurons. Anything this complex cannot be created step-by-step according to Darwin's concept of it happening by a series of fortuitous mutations. Each added mutation must be usefully functional by itself, following Darwin's rules. My bold points out the thought the neurons did it by themselves. Follows dhw's magical thinking.