Original Repository: Alan Mason Chesney Medical Archives. Daniel Nathans Collection
Reproduced with permission of Ernest Winocour.
Medical Subject Headings (MeSH):
Simian virus 40
Nucleic Acid Hybridization
From Phage MS2 to Tumor Virus SV40, 1962-1970
Letter from Daniel Nathans to Ernest Winocour (August 18, 1969)
July 23, 1969
I hope you had a pleasant trip back to the U.S., and that the shock of re-entry was not too great.
Here are some interim results (see attached graphs, tables, etc.):--
(A) Size of the synthetic RNA. The gel electrophoresis patterns seem nice and clean. Most of the c-RNAs are fairly homogenous
at 1S to 2S (100,000 to 200,000 M.W?). There is some big stuff (or double stranded RNA?) at the origin, in each case.
(B) Hybridization. Experiment 1. I first checked the hybridizing capacity of the "denatured" SV40 DNA II preps that
you left me. From the data in experiment 1, it seems clear that they were incompletely denatured (both the unlabeled and 14C-labeled
preps). It is interesting to note from reactions 7-12 that whilst the hybridizing capacity jumps 8-fold after the second denaturation,
the amount of DNA absorbed to the filters (from the 14-C counts) is approximately the same in each case. It, therefore, seems
likely that much of the SV40 DNA II without the second denaturation (though absorbed to the filters) was not available for
hybridization. For the filters in the following experiments, I therefore combined your SV40 DNA II + 14C-SV40 DNA II (to make
100 cpm/[micro]grams) dialysed the mixture against SSC/100 and denatured by boiling for 15 mins.
Experiment 2. There was only 0.4 ml of the late SV40 RNA (from BSC1 cells) left and as you can see I never reached saturation.
Nevertheless, with the remaining 0.3 ml of late SV40 RNA (!) I did experiment 3. It seems to suggest that the cold synthetic
RNA completely competes with "late" SV40 -- cell RNA. Of course, this must be repeated with saturating amounts of
the late RNA. I am preparing another batch and will be ready to do the repeat competition experiment next week.
We are all well. The Egyptians got a lovely bashing at the canal the other day. So we may expect some quiet and tranquility
there until they recover. But the big news at the moment is your men on the moon and Israel is full of admiration.
With greetings to Jo-an and your boys from myself, Audrey and our boys.
[TABLE="Exp. 1. Capacity of SV40 DNA II (D.N. Preps), with and without Further Denaturation to Hybridize with 3H-SV40
[TABLE="Exp. 2. Hybridization Between a Fixed Amount of 14C-SV40 DNA and Increasing Amounts of 3H-RNA (late) from SV40-infected
[TABLE="Exp. 3. 'Competition' Between Late 3H-SV40 RNA (from infected BSC1 cells) and Unlabelled Synthetic SV40