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  [Aroid-l] What is Aneuploidy?
From: pjm at gol.com (Peter Matthews) on 2008.01.14 at 03:19:41(16950)
Dear Ted,

>1. How reliable are chromosome counts, statistically? How many cells do
>you need to count before you are satisfied that you have the right number?

Some kinds of plants are more stable than others, but many plants (like
Colocasia eesculenta - taro) are very stable - i.e. one clear count on
one cell from one tip is likely to be the full story. Ferns with
hundreds of tiny similar-looking chromosomes are hard to count
accurately, and may also be more unstable in terms of number.

>2. Is it possible to have a nuisance cell or two that show a different
>count from others from the same plant? I mean, what do you do if you
>count, say 20 cells with 2n = 40 and one with 2n = 42?

Count more cells, confirm, and report!

In my experience, this sort of thing is a reflection of poor preparations
with spilled chromosomes and difficult, inaccurate counting.

If the counts are all clear and accurate, and the unusual number is real,
then there could be some interest in counting many more cells to
establish a frequency of occurrence, and measure the instability in cell

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