February 10, 1955
Dear Francis
I have put off writing because I hoped to be in a position to write a longish letter. First of all, I have done nothing with the Virus Paper. Reason is preoccupation with many things. However I seem to be returning to work at a steady pace. Visitors seem to choose this time of year to descend on Pasadena. The following factual information may interest you.
1) RNA -- shows no increase in UV absorption on boiling for one hour (TMV, Yeast, Liver) Nevertheless shows 20 percent rise when taken from .1 M NaCl to H2O. Have been drawing fibres from some new Yeast RNA of S20 10-12. Seems to behave like previous samples This is a pity. No x-ray pictures yet, but birefringence and stickyness [sic] seem similar. This should be very clear RNA so I wonder whether sample improvement will help us. We should probably concentrate on obtaining better photographs from present samples. Hope soon to get x-ray photos and sedimentation pictures from boiled RNA -- this to check whether specific hydrogen bonds exist -- would guess they don't. Am going to Berkeley next week to look again for RNA in E.M.
2) TMV Caspar (now here at Caltech) doubts whether Rosy's sign assignment [?] for Equatorials is right. If he is right in his guesses, we find a high density about n equals 20 PO4?? Probably would pay to talk to her. M.W. of TMV RNA seems to be 240,000 Are there
[END PAGE ONE]
[BEGIN PAGE TWO]
8-10 chains running down the core as follows [diagram]. He guesses low density in the very center; to be expected if the bases are on the inside. TMV remains the H2 of the RNA world, that is unless PUX is pushed. What about having Roy Markham prepare you some. --Or is Rosy doing it.
Southern Bean Mosaic: Caspar has low angle curve (Dumond Equipement [sic]) in water and high density salt. First picture gave approximation to uniform sphere -- second gave nothing. Hence RNA is likely to be highly hydrated.
Bacterial Microsomes: We are preparing them from E. coli for both low and high angle. Since they are 50 td [?] RNA, am curious whether we shall see RNA powder pattern. Have new analytical Spinco at disposal -- necessary in this work.
Gamow was here for 4 days -- rather exhausting as I do not live on Whisky. Your TIECLUB note arrived during visit. Am not so pessimistic. Dislike adapters. We must find RNA structure before we give up and return to viscosity and bird watching. I should like more physical-chemical data before I return to model building -- This we have before summer.
My visit to England: still plan to come by early summer. However certain uncertainties about academic future make simple planning impossible. Will write when things clear up -- may not be for several monthes [sic]
My visit East was pleasant. Am returning in mid March for several weeks
Regards to Odile -- am looking forward to return to Unit
Jim