Original Repository: Alan Mason Chesney Medical Archives. Daniel Nathans Collection
Reproduced with permission of Joanne Nathans.
Medical Subject Headings (MeSH):
Restriction Enzymes and the "New Genetics," 1970-1980
Letter from Maxine Singer to Daniel Nathans (March 14, 1972)
March 1, 1972
Mr. Carrol is picking up some H. influenzae restriction endonuclease today and Kathy Danna will include a note regarding activity
and use for digestion of SV40 DNA. I hope this will be enough enzyme for you to do the things you planned; if not, please
let me know.
Let me tell you what we have done with DNA from defective SV40. As I told Ernest in an earlier letter, we were in the process
of repeating earlier experiments which indicated that all the normal H. influenzae enzyme fragments were present in the digest
of DNA from defective (light) particles, and in addition there were three and possibly four new fragments. We have done this
analysis now on several different preparations of form I DNA, both from light SV40 virions directly and from the Hirt supernatant
of cells infected with high passage stocks. The interesting thing is that all the usual fragments are present, but the new
pieces are consistently daltons, as estimated by electrophoretic mobility. These fragments may well have the cellular DNA.
I would like also to check this point, but I have no answer as yet and will keep in close touch with you and Ernest.
The other experiments of interest to you concern the order of fragments in the molecule. We have an order of synthesis by
pulse-labeling and Kathy Danna is analyzing partial digests to determine the physical order. I'll also keep you informed
of these results.
I hope you are enjoying your time with Ernest, and in Israel, as much as I and my family did when we were there. Actually
we are all anxious to get back to Israel soon; one of my sons will spend the coming summer there, but the rest of us will
stay in the U.S. Incidentally, I have just become chairman of the Microbiology Department at Hopkins, which is likely to restrict
my sabbatical hopes for a while.