Sunday, November 13, 2005

Functionality of Sleep

NEUROSCIENCE: SLEEP AND THE BRAIN: "the brain is relatively quiescent during slow-wave sleep (when the EEG is dominated by sleep spindles and high-voltage slow waves). But it must be emphasized that such global deactivation is only relative. Although consciousness is dulled, the brain is still roughly 80% activated and thus capable of robust and elaborate information processing. Thus, the EEG spindles and slow waves represent changes in the excitability of cortical and thalamic circuitry and should be regarded not simply as 'noise', which subjective experience leads us to assume, but as signals used by the brain for its own functional purposes."


CELL BIOLOGY: ON CRYPTOCHROMES: "The term 'cryptochrome' began as a generic label for photoreceptors in plants that were responsible for plant responsiveness to blue light. After the first blue-light receptor was cloned in Arabidposis thaliana, the term cryptochrome came to mean a photolyase-like photoreceptor, due to its sequence similarity to photolyase, a DNA repair enzyme activated by blue light. Cryptochromes (CRYs) are thought to have evolved from photolyases several times independently."
Sunday, November 06, 2005

SAR11: Proteorhodopsin: Odd Energy Mechanism In Bacteria Analyzed

Odd Energy Mechanism In Bacteria Analyzed: "SAR11 has its own mechanism to use sunlight energy that does not involve chlorophyll. Rather, it uses retinal, the same protein used by the eyes of animals and humans to detect light, and serves as a 'proton pump' to energize the cell membrane. "
Thursday, November 03, 2005

Apoptosis - role of mitochondria

Apoptosis - role of mitochondria: "Mitochondria play an important role in the regulation of cell death. For example, anti-apoptotic members of the Bcl-2 family of proteins, such as Bcl-2 and Bcl-XL, are located in the outer mitochondrial membrane and act to promote cell survival. "
Wednesday, November 02, 2005

Membrane Fusion - computer simulation

Max Planck Society - Press Release: "The fusion of membranes is essential for many processes in the human body, for instance, in the communication between nerve cells. A single fusion event occurs on the nanometer scale and takes less than a millisecond. Using computer simulations, scientists at the Max Planck Institute of Colloids and Interfaces have now been able to observe single fusion events with molecular resolution. The simulations are based on new computer algorithms by which one can investigate two large membranes which contain more that ten thousand lipid molecules surrounded by about three million water molecules. These simulations reveal that the fusion process can be controlled by the initial tensions within the membranes. Fusion occurs only at intermediate tensions but, when it occurs, it happens extremely quickly and is completed within 200 nanoseconds. (Nature Materials, Advanced Online Publication, February 13, 2005)"

Patch Clamps ion channels

Los Alamos National Laboratory (LANL): Scientists propose new method for studying ion channel kinetics: "Using a data set of patch clamp recordings, the Los Alamos researchers can apply the MIR method to mathematically reduce the level of redundancy among the millions of possible ion channel topologies. Patch clamps are instruments using in studying ion channel kinetics. The overall goal of the research is to provide tools and strategies for understanding the topologies of ion channels that allow researchers to focus on smaller, more manageable data sets."

MIR ion channels

Los Alamos National Laboratory (LANL): Scientists propose new method for studying ion channel kinetics: "Scientists working at Los Alamos National Laboratory have developed a new method for the study of ion channel gating kinetics. An ion channel is a protein pore that lets ions (charged atoms such as calcium) pass through a cell's membrane. The method fits data to a new class of models, called manifest interconductance rank (MIR) models, which will give researchers a better understanding of the mechanisms by which ion channels open and close.

Researchers have long been able to isolate a single channel and detect the flow of ions and to electrically observe whether the channel open and closed. By looking at how long the channel stays open or closed, they also could infer that there are several different open and closed states. Using models called Aggregated Markov Processes, the researchers are able to represent the undetectable changes between different open states, and between different closed states. However, there are an enormous number of ways to connect even a small number of states. For example, only four open and four closed states connect in more than 2 million possible ways."
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