Beta Rhythm (Music of the Mind)

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...

Genetically Engineered Mice Defy Aging Process Scientists have prolonged the lives of laboratory mice by 20 percent using a technique that boosts the natural antioxidants of the body. Scientists Find Anti-Aging Gene in Mice The discovery was triggered by a study Kuro-o and his colleagues published in 1997. That study identified a gene in mice that, when damaged, caused the animals to experience all the hallmarks of aging in humans -- hardening of the arteries, thinning bones, withered skin, weak lungs -- and to die prematurely. They dubbed the gene Klotho, for the Greek goddess who spins the thread of life. Suspecting the gene may play a role in regulating life span, Kuro-o and his colleagues genetically engineered mice with overactive Klotho genes. In the latest experiments, they found that these animals lived an average of 20 to 30 percent longer than normal -- 2.4 to 2.6 years vs. a normal life span of about two years -- without any signs of ill effects, according to the new report....

Adam Heller at the University of Texas at Austin has developed an implantable electrode module , the first component of a biofuel cell in which glucose is electro-oxidized at the anode and oxygen is electroreduced at the cathode at neutral pH. The volumetric power density of the cell, including the liquid passing through it, will be around 1mW/cm at the glucose and oxygen concentraions of arterial blood. The secret to the fuel cell's size and performance is the use of microfibers rather than flat electrodes and the enzyme-based electroactive coatings. This electrode design avoids glucose oxidation at the cathode and O2 reduction at the anode, Heller points out, eliminating the need for an electrode-separating membrane, which is difficult to produce and enclose when small. The anode coating is glucose oxidase covalently bound to a reducing-potential copolymer that has osmium complexes tethered to its backbone. The cathode coating is similar but contains the enzyme laccase and an ox...

Lately I've been listening a lot to Kate Bush's album Aerial - beautiful, wonderful stuff. The album cover is interesting too - the 'islands' that are reflected in the water are actually the amplitude envelope of a recording of some birds singing. This idea of 'looking at sound' in different ways has been something I've really enjoyed exploring over the last several years. To help visualize the harmonics in a piece of music, I wrote a program a while back that analyses the frequency content of a sound waveform and creates a spectrogram (spectrum over time) of it, colour coding the intensity levels of each frequency. I think I've found the bird song shown on the cover - it's 2:25 from the start of the song 'Aerial'. Here's what its spectrogram looks like: The parallel contour lines that are stacked one on top of each other are the harmonics of the bird song. (A synthesizer's been added to the recording, which has changed the amplit...