Beta Rhythm (Music of the Mind)

Previous blog entries have covered what Neurotransmitters are , and how synaptic receptors use these molecules as triggers for complex actions once they have crossed the synapse. This blog entry explores the other side of the synaptic cleft, where the neurotransmitters are stored and released. Nature has developed some amazing machinery to make synapses fire quickly. Relying on the cell nucleus to generate the molecules that act as neurotransmitters when they are needed would be far too slow to achieve the kind of speed required to power thought. Instead, these molecules are made ahead of time, before they are needed, and are kept bottled up in spherical containers called 'vesicles', waiting for the instant that they need to be released. The picture that is evolving on how synapses actually manage this feat is quite fascinating. And, once again, that super cool molecule called 'clathrin' plays a major role... From http://www.hhmi.org/research/investigators/sudho...

You often hear about neurotransmitters in the news and in science magazines in a kind of off-hand way that assumes everyone must surely know what these things are. But, um, what are they, exactly? From Sandra Ackerman's book "Discovering the Brain" : To be recognized as a neurotransmitter, a chemical compound must satisfy six conditions: It must be synthesized in the neuron, stored there, released in sufficient quantity to bring about some physical effect; when administered experimentally, the compound must demonstrate the same effect that it brings about in living tissue; there must be receptor sites specific to this compound on the postsynaptic membrane, as well as a means for shutting off its effect, either by causing its swift decomposition or by reuptake, absorbing it back into the cell. OK, well, what about hormones? They're chemical messengers too - how are hormones different from neurotransmitters? A hormone, by definition, is a compound produced by an end...

From Paul Greengard's Nobel Lecture in 2000 : It is estimated that there are about 100 billion nerve cells in the brain and that on average each of these nerve cells communicates with 1000 other nerve cells. A vigorous debate went on from the 1930s through the 1960s as to whether intercellular communication across the synapses between nerve cells was electrical or chemical in nature. The electrical school of thought held that the nerve impulse or action potential was propagated along the axon to the nerve ending, changed the electrical field across the postsynaptic plasma membrane, and thereby produced a physiological response. The chemical school believed that when the action potential came down the axon to the nerve terminal, it caused the fusion of neuro-transmitter-containing vesicles with the presynaptic plasma membrane, releasing a neurotransmitter, which then diffused across the synaptic cleft and, through activation of a (hypothetical) receptor, produced a physiological res...

From the University of Hamburg's website: Clathrin and Coated Vesicles : Clathrin is a protein with an extraordinary structure. It is a trimer with three leg-like subunits. Its extraordinary structure enables the protein to polymerize in a two-dimensional network consisting of numerous hexagons. Strictly speaking [the aggregate forms not a plane but] a bent surface with a convex and a concave side. It is an open question whether the tendency to bend has intramolecular or intermolecular causes. Especially important is the fact that such networks fit with their concave side tightly to membranes, for example to the inner surface of the plasmalemma. The growing network provides the mechanical force to pull the membrane into a bud. This bud is finally pinched off: a clathrin-coated vesicle has been formed. Coated vesicles are known to exist in a range of plant and animal cells (E. H. NEWCOMB, 1980). They bring extracellular substances into the cell, a process called endocytosis. Withi...

The series of notes on molecular biology I posted initially to this blog have been moved to a new blog: Nanobiology Notes : Just add water... Fun with Molecular Origami Chromosomes: Good things come in very small packages Protein formation: Codones, Histones and Ribosomes Life and Ligands Ion Channels: gates in the cell wall Enzymes: Come together, right now, over me. ATP: Power to the people, right on!

As long as I can remember, I've always enjoyed designing and building stuff. I have clear memories of building things with tinkertoy when I was around 3 years old, and as I grew up I made the usual progression through Lego, mechano, balsa wood models, electronics, software, ... The stuff you can build is limited only by the properties of the building materials, your skill level and knowledge, and your imagination. Well, wouldn't it be cool if you could build stuff out of molecules? If, through synthetic biology, you could craft some DNA to create the necessary infrastructure within a cell to create a tiny manufacturing plant for, say, carbon nanotubes? First thing to do when some far out idea like this pops into your head is to see if someone else has thought of it too (which is almost always the case). c.f.: http://ej.iop.org/links/q30/2N8tYInWNdqdYgCQ2+AZJg/nano5_1_R01.pdf As we become more adept at modifying proteins not just for binding but for catalysis, the nanotechnolog...