Bk ee PATA a hE Le a alten Ea tl Re pet RE A de hie naa lhl ag UNIVERSITY OF CAMBRIDGE : g PROFESSOR R. A. FISHER, Sc.D. F.RS. |. DEPARTMENT OF GENETICS MISS M.F.L SPEYER, B.Sc. =: Research Assistant and Secretary ~ CAMBRIDGE | oie Maree at gives. “better ‘results ‘Gates and 3 nicer "prototiophs = it further $s your renark as well as Mrs. “show interesting too. It is possibile that | ‘lysogenicity may be a widespread barrier. “gains | byrbridization ( by the way,is the offsnring ‘resistant ?4f so,isolation of -a resist: nt strain might increase yields oc nsiders ably,ond T an lockins forvard ‘to the’. “Tederberg!s Totton are very iVuainating 5 resistant strain you are Locking for). Perha aps with: ‘organisms of great reproductivit “as” hacteria the task of Hature is thet of ‘preventi ng outbreeding rather than favouring. Tt as with higher orgvanisns. As to, (growth requirezents of 123,all. I mew about it soue tine - ego wad that it Z.) uld pie on 3 (hoped to be vitamin-free) casein. hydrolysate. In Becember T spent. “a week lasgow at Fontecorvo! s Departnent, where I also courageously’ ‘pare - ‘a public | desonstration of crossing bacteria at the-presence of S§ceptical vacteriologists. ' One * > of them was Lomins! ci, to whom IT am sending the cultutes now. “After. ‘the show, ‘they - seemed to. be convinced that there may be something in it,which is a great achievement, vt think. We then made with Ponte some experiments to establish growth requirements of. 123 and could see. that a really vitamin free ,acid hydrolysed casein supported growth,” ojo but ‘hydrolysed: itete-did not; Later Pont# could- be ihar arate phd ae oarrrremenac : methionine to insulin gave growth. He is interestei to the strsin “ecause -he hopes ‘that there may be 2 polypeptide requirement in viev. I am-now trying single omissions from an artifii cially reproduced insul in, but lack some of the aminoacids. Anyhow, ‘the a growth reguirenents should be prett complex, b® we roll ine «i methionine TI. cculd ynot. got ony hottor back mutants. db is therefore likely that two or more other aminoaci are involved. Perha-s you have already a.clus to the problem, and your results will be tae weltomed. . “ me or ~ _ Coming to th ne second ot of your letter at wish to. thant: you very mich for your” ttention to my person. har tresent postion here is an’ agpoWatent as assistant of research for three vears,renewahle, with a not too bad salary for s junior post. One. of aod most ardent wishes is of covrse that of srending a year or mich more in Fhe State 1 is of a year is little @oapatiblé with a facil’ of tro vnttinenat which one expected, Trerefore T never tried so far to seek 2 rendiien-cae er sinilar. The best eo 7promise petween family needs and scientific interest would - be thet of spending as socn as nossivl® tvo or, three months,prefernbly in the summer if the. peovle I am interested to meet (zou are the first of course) ere not away. ‘on ‘holiday. IT nade a first unsuccessfiil trial for a sumer teaching. pest for st tatistical “genetics; it may be succes shal ‘sone other year, bug, 2 perhe 2ps Cold Spring Harbor ‘may. . better excuse. I don't lmow however that will be on Tn sumer 1950. A counlé-of months. in your leborstory will not allow me to ‘start on a serious works Dut . wohldhe. of tremendc help for solving. shorter problems of which there is always. plenty, Seeing techniques and above all have. the leisure of discussing problems with. ‘you-at length: 3 niore tunetely ‘TI have no immediate solutions eveilable,, FOR, this aes _For the far future Th uw. Sy ‘due’ dota. *on the attraction of working ‘in. “the U 8, 4 ork iSteeSSine 1 pos sibility” af an ‘even “te-mpétery ‘dont erie oe ‘for a] n ) foving to the U.S.,even for a good appointment might be ted ‘a fi e*how. ¢ the basis of. private grounds vith which I 6or1a not: like to 1 ‘bother 3 ‘you, bu Ir “have this” plan in mind for a not “to00- ‘far. future vend it-is very. gratifying: to frva you that you are willing to help ne,ond may be in a position to ae So gin.’ ot Oo cuplete the phtturesanyhows, the end of this -onth, and 2s to ny qualifications ‘L hold an tbalian X. the usucl Canbridge MA. rdnted oO University officers. Bykhe | wey Aid tell ‘you we that I am giving since. ‘last year a course in Microbial Genetics a this University..? . T. ‘may ‘be able to get a- Cambridge Ph.D. in genetics if there will. “be | no. ‘puroeratic. iff - culties against it. ALL this information. may be useful, ,if not nO, ing a “E hopes. not “400 ais tant future “ ml . ” - «Thank-you very nuch for Letting me “new of the developnent of @iploda. analysis. “Do'you think that. the_ possibility of aneuploids with dup&lics .tions for certain chrdno- Some segments, arising through a. translocati on or Similarin the original strains,is to be digearded? Tt certainly would not explain =ruzsin the rare crossing-overs in: “Giploids,but 4 it mey be after all thet. Ngomatic" crossin--over (putside independent of meiosis) hese - ir not impossibZle in bacteria. Ly UV killing curves in the couparison of asia “Lae and Hfr ‘are multihit; I:fancy what X-ray curves wilk be, but, with anclogy .to B/r fa EAt well be sincle-hit Curves: gre 9 vour stateaents -2 about multifinleation entirely o~ -morgholoticaly org aiso ‘genetical A 2ar;aps an- analysis of. recessive. mutations. “might “help,and. I -have ee thinking for some’: tine. of doing,it for theconparison of Nfr and “HET, should. the Ffr behaviour have amr. “connection. with ait: The. Adentity of ‘UY killing -evrves in both strains THEBES TSO that average number: of nuclei ser cell might “be the ‘sane. OT ee co, woe “t-My work is delayed ,or r could “better: say desperately - lagging, for lack .of .ade- : “quate - -tecnical help and for very irritating difficulties like a marked decrease of - yo “all recombinations sthnee a longish time 3 elinin ation of possibfle causes is not yet ‘finished,but I am left to the hopeless ones Like -influemte of copper Pek distilled || woter. and anslogous onesé . . oO fire yor Om] her 0 saan f rk ee I am enclosing a copy of a list of symbols I am planning to wet eo mgd 2 ti igual to send a list of strains available,especially because it may be of help to Europpan research workers to know which of the K-12 strains (I am excluding Het) they . might be able fo find on theirncohtinent. But it occurred to me that,unless one standardise: ae "symbols for the most simix frequent mutants, description of your strains will take pages. So a standard list of symbols for the most frequent types of growth requirexen may be of use for this and similar prrposes. Yours sincerely PLS. ‘Pontecorve 88 e me wis dried- cultures cogschil _potants af Aerobacter aerogenes. ‘He told. me you Eee “interested. to have thes ime ago...There -is. about, a-dozen. of adapta able and @ dozen of non-a daptable. nay ene ee you. still interested in them ? If. 80,please let ‘me know.’ a have not checked the ade. leptable. cultubes but for viabi- eee apie glen Leet .. Gu: Guanine | Boa ~ Al‘, alpha-alanine. Am “aminobutyrte ecid Sar “arginine As aspartic acid Ci citrulline Cc cystine ' Ce cysteine Dp dihydroxypnhenylalanine Ga glutamic acid G glycine histidine Hp hydroxyproline I isoleucine Vitamins. Anmeurin (B ) R Riboflavin (3) Py Pyridoxine (Be) F Folic acid (B,) Pa PantotBenic acid Na Nicotinic acid/amide Purines and Pyrimidines , Ad Adenine Cy Cytosine x Ly Nl Nv Ph Se ‘Tr Ty Ch In | Co Hx Th Bu Xanthine eth sie eA ye eo et eves teed Dh Sekt dia th Me ea A A ee ee ke i Deeg oe Symbols for growth-Facto# deficiencies. ‘ Aminoacids. Leucine Lysine Methionine Norleucine Norvaline . Ornithine Phenylalanine Proline Serine Threonine Tryptophane Tyrosine Valine Paraaminobenzoic (PAB) acid Choline Inositol Biotin Me thylnaphtoquinone Cobione (B, 5) Hypoxanthine Thymine Uracil