Mitotic spindle and magnetic poles.

Robert Clark rgregoryclark at
Sat Nov 29 04:50:55 EST 2003

Take a look at the image of the mitotic spindle of a Drosophila embryo
in Figs. 1,b and 1,c on this page:

1. Study of the Effect of Electric Fields on E. coli

 Note that the spindles are straight close to the middle but are more
rounded further out.
 Then compare this to the images of the field lines of magnetic and
electric dipoles on the same page in Figs. 2 and 3. They are also
straight close to the middle but more rounded further out.
 A definitive test would be to use the very sensitive magnetometers
available now to see if the mitotic spindle generates a magnetic
field. Inexpensive magnetometers are available now that can measure in
the nanotesla range or 10 microgauss. As a comparison the magnetic
field of the Earth is on the order of .5 gauss.

     Bob Clark

r norman <rsn_ at> wrote in message news:<n678svknctqsnub9qerajfaie5ueprr783 at>...
> On Tue, 25 Nov 2003 20:08:46 +0000, Tom Anderson
> <ucgatan at> wrote:
> >On Tue, 25 Nov 2003, r norman wrote:
> >
> >> On 24 Nov 2003 22:06:58 -0800, rgregoryclark at (Robert Clark)
> >> 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.
> >
> >Ah, but if that was all it was, the spindle fibres would be straight,
> >wouldn't they? They aren't, they definitely curved.
> >
> Are you sure they are curved?  Don't look at diagrams or drawings.
> Look at pictures of the fibers.  Tubules tend to be straight except
> that they are flexible and can bend around obstacles.  The pictures of
> the kinetochore tubules (the ones that attach to chromosomes) and the
> astral tubules (the ones that radiate out) are distinctly straight
> except when there are obvious obstacles bending them.  The polar
> tubule (the ones radiating from pole to pole without connecting to
> chromosomes) are different.  These are curved for a different reason.
> Each one radiates out straight from the pole but, when they meet, they
> tend to become aligned.  These do have a curved shape somewhat
> reminiscent of the field lines of a dipole (electric or magnetic) and
> for the same reason that things that radiate out from one pole and
> converge on another must necessary curve in between.
> There is still no relationship to a magnetic dipole even though
> intense magnetic fields may disrupt tubule formation.

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