miglia at nserv.icmat.mlib.cnr.it
Thu Nov 13 12:27:59 EST 1997
The experiment "SOUTHERN ARABIDOPSIS" has been completed. Two researchers,
Peter Hare from South Africa and Helen Mitchell from Australia (to whom many
thanks are given) did it by growing Ws seedlings on hard-agar plates. The
result (not very exciting!) is that arabidopsis roots behave in the same way
in both Hemisphere of the earth, e.g. the roots, as seen from the top of the
plates, coil clockwise and thus show a right-handed symmetry. Consequently,
the latitute of the earth does not affect root symmetry, as it was expected
considering what happens with snails (right-handed) and twining plants
(right or left-handed).
The result naturally is not particularly exciting, however, this is an
experiment that had to be run, not only to satisfy the curiosity of the many
peiple who asked about it, but also because we could not exclude a priori an
effect coming from the geographyc latitude on plants. Moreover, a weak
effect, that cannot be detected with simple experiments, is still possible.
For instance, the chirality of arabidopsis roots could be reduced,
increased, or modified in different earth zones, not to speak of the effect
of microgravitational conditions on the chirality, that are still to be
investigated. It is an area that deserves further research.
A last thing to consider is the behavior of a water jet. It is true or not
that a water jet fall down turning to one hand in the Northern Hemisphere
and to the other hand in the Southern ? I am not a physicist, and thus I
cannot answer this question. Ann Britt answered that is an old wives tale.
Can somebody tell us something more about the origin of this tale?
I thank all the people who took part in the experiment, or got interested in
it, and hope to have soon something more to report about the weak effects of
geographycal latitude or microgravity on root chirality in arabidopsis.
Down here the most of the answers to the SOUTHERN ARABIDOPSIS experiment is
I would be happy to try your experiment for you. It so happens that I
have some seeds of Ws which I sterilised only yesterday. Please could
you clarify one point for me though: I do not use commercially available
salt-mixes for MS medium : is the 2.5 g/l you specify the equivalent of
half-strength or quarter-strength Murashige & Skoog (1962) medium? I
doubt it would make a difference - if I don't hear from you, I'll settle for
half-strength, which is what I usually use anyway.
I will let you know how things go. Obviously, the more people that do the
experiment in the Southern hemisphere th better!
Department of Botany
University of Natal
Private Bag X01
I am writing to you from a molecular biology lab in Australia, in the
Southern Hemisphere. We routinely grow arabidopsis seedlings on hard agar
in petri-dishes, before transplanting them into pots. The petri-dishes
are incubated horizontally. When viewed from above (through the top of the
petri-dish), the roots always coil in a clockwise direction. When viewed
from below (the bottom of the petri-dish) the roots coil in the
anti-clockwise direction. I hope this is of some use.
I think that thing about water swirling the other way in North vs. South is
an old wives tale. The water will swirl either way in either hemisphere,
depending on local influences and initial momentum.
Nonetheless, its a pretty easy experiment to do!
Finally S. Baum and T. Rost published something recently about the spiral
pattern of cell division in roots- perhaps that has something to do with it?
Section of Plant Biology
University of California, Davis
Davis, CA 95616
fax: (530) 752-5410
phone: (530) 752-0699
Very glad you sent that request on the network. Indeed, we have also been
asked that question very often. Can you share the information with us if
someone agrees on doing the experiment?
Thanks, and best regards,
Thank you for your reply. I'm glad you clarified that issue for me before I
go home tonight. Yes, I did leave three plates oriented horizontally and
now about 30 h later, I can see that the coils appear to be clockwise. But
I will continue to observe the plantlets for a while. If you have any use
for it or think that there there may be a difference in the "period" or
"frequency" (?) of the waves/diameter of the coils (I am guessing..?),
with latitude I would be happy to send you photo's.
Otherwise, it was fun for me to do the experiment (especially when I
thought there might be an effect!!!). Good luck for all your research.
Peter (Peter Hare).
* Dr. Fernando Migliaccio *
* Institute of Plant Biochemistry *
* and Ecophysiology/ CNR *
* Via Salaria Km. 29.300 *
* 00016 Monterotondo (Roma), Italy *
* ph:+39 6 90672530; fax:+39 6 9064492 *
* email: miglia at nserv.icmat.mlib.cnr.it *
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