Motor Neurons Derived From Embryonic Stem Cells
September 03 2010   |   Permanent Link
Via EurekAlert!: "Scientists have devised a method for coaxing mouse embryonic stem cells into forming a highly specific motor neuron subtype. The research [provides] new insight into motor neuron differentiation and may prove useful for devising and testing future therapies for motor neuron diseases. ... The existence of dozens of muscle groups in the limbs of most mammals demands an equivalent diversity of motor neuron pool subtypes ... During normal development, motor neurons settle into specific sections of the spinal cord (called columns), which correspond to the muscles that they will innervate. For example, cells in one area link up with muscles in the limbs, while cells residing in another region innervate muscles in the body wall. Although previous studies have shown that mouse and human embryonic stem cells can be converted into motor neurons, it was not clear whether these were 'generic' neurons or whether they could acquire characteristics of the specific specialized subtypes. In the current study, [researchers] showed that removing a key differentiation factor allowed cultured embryonic stem cells to form motor neurons with molecular characteristics corresponding to a limb innervating subtype, without the need for genetic manipulation or added factors. Importantly, when this stem cell-derived subtype was transplanted into embryonic chick spinal cords, the motor neurons settled in the expected columnar position within the cord and had projections that mimicked the trajectory of limb innervating motor neurons."

An Overly Narrow View of Genomics
September 03 2010   |   Permanent Link
Ray Kurzweil in h+ Magazine: "There has been recent disappointment expressed in the progress in the field of genomics. In my view, this results from an overly narrow view of the science of genes and biological information processing in general. ... To reverse-engineer biology we need to examine phenomena at different levels, especially looking at the role that proteins (which are coded for in the genome) play in biological processes. In understanding the brain, for example, there is indeed exponential progress being made in simulating neurons, neural clusters, and entire regions. This work includes understanding the 'wiring' of the brain (which incidentally includes massive redundancy) and how the modules in the brain (which involve multiple neuron types) process information. Then we can link these processes to biochemical pathways, which ultimately links back to genetic information. But in the process of reverse-engineering the brain, genetic information is only one source and not the most important one at that. So genes are one level of understanding biology as an information process, but there are other levels as well, and some of these other levels (such as actual biochemical pathways, or mechanisms in organs including the brain) are more accessible than genetic information. In any event, just examining individual genes, let alone SNPs, is like looking through a very tiny keyhole."

A Reminder that Fat Doesn't Just Sit There
September 02 2010   |   Permanent Link
Excess fat tissue in your body actively works to change your metabolism, and largely for the worse. Here's a reminder of that fact: "Scientists are reporting new evidence that the fat tissue - far from being a dormant storage depot for surplus calories - is an active organ that sends chemical signals to other parts of the body, perhaps increasing the risk of heart attacks, cancer, and other diseases. They are reporting discovery of 20 new hormones and other substances not previously known to be secreted into the blood by human fat cells and verification that fat secretes dozens of hormones and other chemical messengers. ... [Researchers] note that excess body fat can contribute to heart disease, diabetes, cancer and other diseases. Many people once thought that fat cells were inert storage depots for surplus calories. But studies have established that fat cells can secrete certain hormones and other substances much like other organs in the body. Among those hormones is leptin, which controls appetite, and adiponectin, which makes the body more sensitive to insulin and controls blood sugar levels. However, little is known about most of the proteins produced by the billions of fat cells in the adult body."

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