86 
DR. FREDRICKSON: And that paper is going to appear where, Dr. Szybalski? 
DR. SZYBALSKI: It is going to appear in 1977 in Gene. 
DR. FREDRICKSON: Thank you. 
DR. MC CARTHY : Dr. Szybalski, do you mind if we reproduce this and cir- 
culate it here? 
DR. SZYBALSKI: No, I have permission from the authors to reproduce it. 
DR. MC CARTHY: I would hate to be caught in a copyright dispute. 
DR. FREDRICKSON: Mr. Beaty. 
MR. BEATY: In continuing what Dr. Ginsberg was asking about the anti- 
biotic resistance markers and some of the strains which might be eligible 
for an HV3 classification to make it useful as a label or a monitor, a nice 
positive selectable marker which one can separate from the other. 
DR. GOTTESMAN: We have considered that problem, obviously. There are 
two questions. One is in the HV3 testing itself, which requires that you 
feed the organisms to animals and ask what you can recover in terms of the 
plasmid, there one could insert an antibiotic resistance marker for the 
testing, so that is not a problem. In terms of monitoring on a regular 
basis, I agree it does pose somewhat of a problem, but some of the kinds 
of things which we had in mind could be useful in that case. For instance, 
one could use a tetracycline resistance gene with a temperature sensitive or 
an amber mutation on the tetracycline gene itself so that it would not ex- 
press itself in normal wild-type strains, but if you wanted to monitor it 
you could set up conditions where you could monitor it. Those are possibili- 
ties . 
I think we would like to have more input on how people feel about the 
antibiotic resistance business. We had a lot of comments that it is an aw- 
fully strongly selective marker if it is going to cause any trouble, and 
given that versus the monitoring we have opted in this direction for the 
moment . 
MR. BEATY: Also, considering the fact that one could select the resis- 
tance as to antibiotics that are not quite as commonly found and not as 
clinically important. 
DR. GOTTESMAN: Yes, that could certainly be used. I mean, it is ex- 
plicitly stated. That is, it shouldn't be a clinically important one, but 
something which is never used in our environment would serve our purposes 
very well. 
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