Thursday, July 24, 2008

Rnai- A Most Valuable Player

Rnai Discovery Animation is the title of this blog entry at BioSolutions. Rnai is a valued research tool which can be used to manipulate gene expression, thereby yielding information about cellular functions. From the linked article:

The RNAi pathway is initiated by the enzyme dicer, which cleaves double-stranded RNA (dsRNA) to short double-stranded fragments of 20–25 base pairs. One of the two strands of each fragment, known as the guide strand, is then incorporated into the RNA-induced silencing complex (RISC) and base-pairs with complementary sequences. The most well-studied outcome of this recognition event is a form of post-transcriptional gene silencing. This occurs when the guide strand base pairs with a messenger RNA (mRNA) molecule and induces degradation of the mRNA by argonaute, the catalytic component of the RISC complex. The short RNA fragments are known as small interfering RNA (siRNA) which are perfectly complementary to the gene to which they are suppressing as they are derived from long dsRNA of that same gene or MicroRNA (miRNA) which are derived from the intragenic regions or an intron and are thus only partially complementary. The RNAi pathway has been particularly well-studied in certain model organisms such as the nematode worm Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and the flowering plant Arabidopsis thaliana.


Monday, July 21, 2008

Thought Leads to Physical Changes

Neuroscience: Meditation really can change the brain is a blog entry at Mindful Hack showing that rational people can interpret scientific data more than one way when scientific boundary lines are ill-defined. What is ill-defined is the relationship between thought and brain cells, or to be more specific, how changes in one lead to changes in the other. The topic has been broached many times and there is ample evidence that the way one thinks can lead to physical changes in the brain. Materialists attempt to define thought as a mere manifestation of underlying physical (biochemical) events. It is usually depicted by reference to the concept of emergence.

Emergence is a reach in my view. It is the root of the word emergency which describes how a materialist must react to evidence that a non-physical entity, like thought, changes biochemical reactions and even the brain itself. It's a case of philosophy influencing interpretations of physical data. We can measure the effects of thinking as well as the application of intelligence through the manipulation of the physical world when problems are solved or actions taken. But lets not confuse physical effects with a physical description of their cause.

You can believe thoughts are nothing but brain cells if you wish. That's a metaphysical position though. Sequencing is a major theme of this blog. Generally it is mentioned when speaking of amino acids or nucleotides. But sequencing can be thought of in terms of thoughts and brain biochemistry. Which came first, a flash of insight or some biochemical reactions associated with it? If it is ever the former then materialsim is dead.