UNIVERSITE DB PARIS FACULTE DES SCIENCES LABORATOIRE corGENETIQUE 13. RUE PIERRE CURIE, PARIS V°* September 28, 1953 Tél. : ODEon 16-40 Prof. J. LEDERBERG Dept of Genetics University of Wisconsin Madison, Wisconsin U.S.A. Dear Josh, We were glad to have your letter and happy to know that incidents, if any, belong to the past. I meant to answer earlier your questions concerning the idea of inducing little-to-big transformations with suspensions of nitochondria, but postponed writing you because I learned that Rubbo himself was coming to see me. I had a good discussion with him (in@identally, he makes a very excellent impression !) and promised him to write to you a letter preliminary to your discussions with him when he reaches Madison. The idea of na ittle-to-big transformations is, of course, not new, but we never? avout it except a few unsystematic and un~ successful attempts. “In my opinion, the use of mitochondria should lead to success provided one knew how to get them into the cells. I consider it a priori improbable that placing littles in a suspension of mitochondria will do the trick in view of the thickness of the yeast cell wall. I think that what one should try is microinjection. This has never been tried thus far, because, again, of the thickness of the cell wall : yeast cells explode when they are hurt with a’needle. I was planning to try this year injection into zygotes becauge they seem to be much softer and more thin-walled than vegetative cells. I told all this to Rubbo and hore that I made it clear to him - and I want it to be clear to you - that I would be very greatly interested in the results, whoever gets them, and that I therefore well be happy to help by supplying either information, or strains, or both, Rubbo told me of his general plans and objectives of the trip he is starting on, and from this point of view it appears to me more adequate for him to undertake work not on the above subject, but rather on the other subject which you mentioned as a possibility in your letter to him : the action of acridines on bacteria. It seems to me that here is a subject which on the one hand is equally interesting, and which, on the other, will offer him an opportunity to work with K-12 and familiarize himself with genetic problems and techniques (which is the major aim of his trip). UNIVERSITE DE PARIS FACULTE DES SCIENCES LABORATOIRE vreGENETIQUE 13, RUE PIERRE CuRIE, PARIS V° Tél. : ODEon 16-40 Rubbo himself is inclined to look at the situation in a similar Ways Do let me know what you decide and what you do, and do remember that my strains are at your disposal. With kindest regards to both of you, from both of us, pr eve. [hor Boris EPHRUSSI Q pute Arubted ate Hed a. tenee D him _ Bat a evenly 17 qreryete eed ane thet thay Urveg tl Ane lps Ant gt. on ae Os als ob 2 weuted D Liaw 1 ontent etrdvecs ly ; of Lad D te swivlew sage eerces 3g greta hire" are heeegel urs tegcberded proper ipa an AnLw 4 og Aor Pree te Biased / Ae ja teeta has Aho ft Ahe Crerac ete. rl bre yn tr he Uthe wre Apo | a aetigh Nfl wuteen dS Wt thy rearwo, thire we were Labo Q wate'nes Y le tuthns wtb Bccecygrur The ff Q dec a " CHEK GIA -2 fet. VelportiteLlo wm, tke 4 wget! awh — & Legh? Aelia wnt. QD was the Ae es My “) the prt, tan ohe