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needles and buds

Wed Feb 9 03:41:15 EST 1994

Dear yeastnetters (is it politically correct for both the buddies and
just to notes on two unrelated topics "on the net":

1. To DanZ and others who spend a lot of time trying to make a good
dissection needle:
Try to break the fibre between two microscope slides. In our experience,
it gives better ends than cutting with a blade. I and most people in
our lab use manually pulled fibres rather than the optical glass fibre,
but I think that the breaking technique could be the same. But you'll
spend a lot of time anyway, so take care of your needle when you make one.
(A good one can last over thousands of tetrads, if cleened occassionally
by brief boiling first in 0.1 % SDS and then in water, followed by
rinsing in ethanol).

2. To Kati and others wondering why the budding yeast buds:
I don't dare to ask why; I just accept it as given that at certain stage
of yeast's evolution budding happened to be evolutionarily advantageous
or at least linked to an advantageous treat. Perhaps it really allowed
faster division. Howewer, there is one thing about budding people often
do not think about: budding is no "exotic" yeast speciality but rather
a variant of a very old and widespread mechanism for making protuberances
on cell surfaces. Bud emergence requires just two things- making a "border"
(bud neck) on the cell surface and then sending stuff only on one side of 
the border. There are well documented cases in mammalian cells where
similar processes create the differences between apical and basolateral
surfaces of epithelia or even between neural axons and cell body (look
into some recent paper by L. Huber). These processes involve proteins
related to Ras, i.e. to the yeast "budding" gene Cdc42, too. And even
the yeast "neck filament" gene family (CDC3, 10, 11, 12 - see John Pringle)
has close relatives among mammalian genes, some of them expressed in
the brain! The bottom line simply is:
1. It is rather surprising that only the yeast uses budding as a means
for cell division,
2. even our neurons are closer to the yeast than we would expect.


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