Thanks for your letter and the trouble you're taking to put us on the right track. I was of course very sorry to hear
about WH-8, as we had put a fair amount of time in on this culture. I suppose the blame for contamination rests on a god-awful
medium like Levinthal's.
I will pick up the air parcel per your indications. We can stick it into the freezer promptly until we are tooled to use the
A propos the role of serum and DPN, we tried some experiments on the availability of DPN for the adenine requirements of an
adenineless E. coli. It did not replace adenine, nor did bovine serum, but the mixture did. I would attribute this to an enzyme
in the serum which acts as a nucleotidase. As it is no more (nor less) likely that DPN permeates Hemophilus as such, there
may be a comparable function of serum. If so, Hemophilus should be more readily grown in the absence of serum if it is furnished
nicotinic riboside in place of DPN.
I will still wait for the outcome of your --x experiments with WH-8 Sr; there might be a very remote chance that this is still
a mutant of Hemophilus, though this is stretching expectations a good deal.