bchso@uhnix2.UUCP (Dan Davison) (06/17/87)
[List of organisms that can be transformed] >>Gee, Sean, I consider this a handful. But this is a difference in >>philosophy, since the mammalian cell culture transformation you cite >>would never be the same transformation as bacterial, *to me*. >Why not? I don't mean 'growth transformation' or 'neoplastic >transformation', Understood. >I'm just referring to the uptake and integration >of exogenous DNA fragments. Because the conditions under which mammalian cells uptake DNA, and under which E. coli do the same are not very likely to occur in nature. The Gram-positive style of transformation can occur in soil, whereas the calcium chloride bath that E. coli requires is less likely to be be found in its natural environment. dan davison/ bchs6@uhupvm1.bitnet/ davison@bionet-20.arpa / davison@bnl.arpa uucp: ...rice!academ!uhnix1!uhnix2!bchso "Of all the things I've lost I miss my mind the most"
diaz@aecom.YU.EDU (Dizzy Dan Diaz) (06/25/87)
In article <401@uhnix2.UUCP>, bchso@uhnix2.UUCP (Dan Davison) writes: > > Because the conditions under which mammalian cells uptake DNA, and > under which E. coli do the same are not very likely to occur in nature. > The Gram-positive style of transformation can occur in soil, whereas > the calcium chloride bath that E. coli requires is less likely to be > be found in its natural environment. What makes anyone think that E. coli has to be transformed in nature as it is in the laboratory? We still don't understand what calcium does to either of the bacterium's membranes or why heat shock, etc., are necessary. I don't think it that difficult a problem, it's just that molecular biologists have found other projects to waste their time on. My point being that coli and similar bacteria may undergo transformation quite frequently in nature by calcium-independent mechanisms. It would be a mistake for me to measure Vmax or Km for some enzyme in the laboratory and conclude that it or anything else I measure in the lab is actually happening in the cell. I realize that this is heresy to those who think everything we observe at 10 mM TRIS, pH 7.6 at 37 'C is real, but unfortunately, it just ain't so. We just have to go on doing our experiments, formulating theories and making models. Not that it really matters whether what we observe is actually occuring, just as long as we don't pretend too hard that it does. -- .... dn/dx = Dan Diaz (philabs!aecom!diaz or diaz@aecom.yu.edu) ~..|.> Department of Wasting Taxpayers' Money on Useless Research \../ Albert Einstein College of Medicine and Bar & Grill