Re: Mitotic spindle and magnetic poles.

On 24 Nov 2003 22:06:58 -0800, [EMAIL PROTECTED] (Robert Clark)
wrote:

>Has there been any investigation of the possibility that the origin of
>the mitotic spindle really is due to electromagnetism?
> Compare the image on this page:
>
>Media: Mitotic Spindle.
>http://www.meta-library.net/media/mitspin-body.html
>
> To the first image on this page:
>
>Magnetism.
>http://www.warren-wilson.edu/~physics/physics2/Formal_2001/BenWarren/formallab%25202.htm
>

There is no reason to believe magnetism is a mechanism just because
the pictures look similar.  Look at the electric field of a dipole
  http://hyperphysics.phy-astr.gsu.edu/hbase/electric/dipole.html
to see the same thing.

The similarty in shape is caused by processes which share some
superficial similarities but major differences  For the similarities,
first, there are two separate "organizing centers": the spindle poles
for mitosis, and the two poles of a magnetic or electric dipole.  At
each organizing center there is a tendency for lines to radiate from
the center in all directions.  In both the magnetic and the electric
dipoles, the tendency is to radiate outward from one of the poles but
to radiate inward into the other pole.  The result is the
spinde-shaped pattern of field lines.  There really are strong
parallels between the magnetic and the electric dipoles -- one pole
radiates out, the other radiates in.  Add the two together and you get
the result.

In the spindle, the process is very different.  The spindle fibers
radiate outward from both poles.  Some of these, the astral fibers,
always remain that way.  These do not look at all like the magnetic or
electric dipole lines but look more like a magnetic or electric
monopole.  Others meet (either by direct contact as in the polar
fibers or by connecting to the same chromosome in the kinetochore
fibers).  These fibers tend to spread out from one pole and then
rejoin at the other, and so sort of look like the field lines of the
magnetic or electric dipole.  Since the fibers that attach to the
chromosomes are the "important" ones, they are the ones shown in all
the diagrams. 

So in this case, the similarity is really superficial.  However, the
cause of science is always furthered by trying to find relationships
between seemingly very different things -- so keep looking and keep
asking!