RE: Karyotyping and sorting on the Aria

Nicole White wrote (apparently to me and not the Mailing List)-

>Mr. Shapiro:

It's Dr. Shapiro, but, as you have probably 
figured out from reading the Cytometry Mailing List, everybody calls me Howard.

>Here is the attachment just as an FYI but I have to agree with what you are
>saying in the sense that we were all kind of stupefied on our end.

Nicole was kind enough to attach a .pdf file of 
the paper that apparently stimulated her 
correspondent's flight of fancy; it is Michael G. 
Poirier, Sertac Eroglu,and John F. Marko: The 
Bending Rigidity of Mitotic Chromosomes. 
Molecular Biology of the Cell 2002; 13:2170–2179. 
This paper is real science, and is an example of 
a type of research being done by a lot of 
physicists and engineers these days, delving into 
the mechanical properties of biological 
structures. The work on the bacterial flagellar rotor comes to mind.

What the Poirier et al paper concludes is that 
the mechanical rigidities of newt and Xenopus 
chromosomes are different, and (apparently) do 
not vary substantially with the length of the 
chromosome, but depend on the macromolecular 
structure of the chromatid. Their model is of a 
rod, the bending rigidity of which at any point 
is essentially independent of its length. If you 
considered rods made of metal, you would expect 
the bending rigidities of rods of the same 
thickness made of, say, lead and steel to have 
different bending rigidities, and also expect 
thick and thin rods made of the same material to 
have different bending rigidities. The 
differences in bending rigidities between 
chromosomes of different species must come more 
from conformational or configurational 
differences than from compositional differences, 
since the chromosomes are all made out of nucleic 
acid and protein. To the extent to which genetic 
abnormalities in cancer produce notable 
differences in the chromosomes of normal and 
malignant cells, these differences generally 
reflect some combination of deletions and 
translocations, which would be equivalent to 
cutting the rods into different lengths; the 
abnormal chromosomes would therefore not be 
expected to differ substantially in bending 
rigidity from normal ones. This makes it unlikely 
that the mechanical approach to cancer treatment 
suggested by Nicole's correspondent would work, 
and, parenthetically, more likely that the 
correspondent is a perfectly sane and rational 
individual trained in engineering and/or physical 
science and not yet aware that there is much more 
to cancer biology than physics and much more to 
chromosomes than bending rigidity.

And, as long as many biologists and clinicians 
remain ignorant of, and even phobic about, math 
and physical sciences, and even "biomedical" 
engineers and physicists have only the barest 
acquaintance with real biology, there is a higher 
probability than there ought to be that grant 
money and/or venture capital will be wasted on 
interdisciplinary cockamamie ideas.

-Howard