Chromosome numbers

Fernando Rivadavia (ss69615@ecc-xs09.hongo.ecc.u-tokyo.ac.jp)
Wed, 30 Oct 1996 13:13:43 +0900 (JST)

Juerg and Jan,

Thanks to Juerg's references, I found the 1995 article with all
those pygmy Drosera chromosome numbers, as well as the number for
D.falconeri. One of the most interesting points in the article, for me,
was that they found that D.roseana had 2n-6 in 63% of the cells, 2n=7 in
30%, and 2n=8 in 7%. Also, they found that D.dichrosepala had 12
chromosomes, when a few years before it had been counted as 18.
That goes to prove what I said just 2 days ago, that I wouldn't be
surprised if different chromosome numbers were found in a single species
of Sect.Lamprolepis! This group has such crazy chromosome numbers that it
really is no surprise to read this. I had seen that there were numerous
numbers published for D.pygmaea, and now this actually begins to seem
normal.
They mention in the article that no distinct centromeres were
observed in ANY of the chromosomes and that these are probably diffuse.
This observation was also worth for D.falconeri. I don't have the other
papers with chromosome numbers for D.petiolaris and D.lanata, but I
imagine these also have this type of chromosome. In my opinion this may be
another proof of the close relationship between Lasiocephala and
Bryastrum.
It was also observed that the chromosomes often did not pair, with
one being shorter than its counterpart. To me this indicates some
translocation from one chromosome to another and what might be happening
during meiosis is one of those chromosome complexes where they are partly
tied together in 3's or 4's or more.

>Nucleotide sequence analysis will certainly reveal interesting results.

I sure hope so, or else I would be better off stopping now before
actually starting!

Best Wishes,

Fernando Rivadavia
Tokyo, Japan