(fra cecal 49 Soptembor 1945 Dr. 2.L.tatua, Dopt. of Botany, Yole Univaraity, new Havon,Conn. Deas Size Your racent papar X-Ray Induced Mutant Bireins of Ecchorichla Coli! hos just coma to ay attention, and has proven vary fascinating. I should bo vary much obdiged to you for raprints of this paper end your prolininary ona last sumner. I shall teke the liborty of writin: to you at thig length in support of a request that If hope you will anteortain, ° After doing sous work on adaptation (part of which is naarly ssady for publication) in Neurosvora mutants, 1t ocourrsd to m5 taat no sdaquates investigation of a genetic nature had baan uade tO daimonsatrate tha existence or absonesa of sexual rocombination in oacteria. Such things as tho distribution of somatic and flagellar entigeans in ths Salmonslla group very strongly sug.est that suoh & process may occur, but no very succgssful attampt scams to have 330n ade to Gotersiina tha racombineation of bactarial charactszs. he nutritional mutants dascribad by yoursalf and Roapke et al. ‘ould saem to f411 the b4i11. Wa did not havo any of those organisus % this laboratory, but in a otrain of =. coli (6522) I had boon aio to selosct out a mathioninolass strain by serial passage through basal madiua plus sulfanilanids end m3athioning as Kohn and Harris iseribed (J.Bact '41) and a prolinsaloas strain was obtained quite ittudtously (so far as I know) on a platinz of the parsnt wild type. t was interesting that pou also obtainad 2 'prolinazless! as a ponteneous mutant.) No thoroush invostizgation of tha biochsnical aaviour of eitasr strain has boon oads, but it avpoars that the slins requirsment of the latter is very much reduced or sparad snall amounts of tryptopnens, end possible othar amino acids.Un- ‘tunately I do not yet have a very gatisfactory and convanssnt al meciunm, so thet I have not pursusd this further. If you would ‘@ to hava a cultura of this strain for comparison with your otner linsless, I should ba dalightsd to send it to you. I hava not yet gone very far in the genetic tastes I mantioned giicitly) on these strains: the nathioninsless is quita Rough tasrcsfora possibly not oo satisfeotory.I had planned to do ess= lally wnat you have accomplish3sd: prepares a doubis mutant by jecting the prolinslass to ths sase selagctivs procedure used wmtaining msthioninelesss, but thst ssous unnzceasary now for LI ALY) a Gemoustration that indspendent (X-ray aut: xb13) gones exist. It has H3s.sd to 1u9,hox ‘Ovar, that dosrits ths apparsnt stability of ths typos I now hava, a and wnat ds I hére adequato technique to slicinate conta.dnetion that 4% would bs hi: shly- assirable to have genotically “Larksd strains va fox wo any attempt vas made to parforu ths oxparixent. I chould thorafors ba vary much oblisad to you for cultures of your biot im Goubl3 tiutant series for tho purposes of this inavostigation. 40 Gdutnish tha possibility of Contartaation I would like to ask only Zor these goubl?e mutents in which tho blotinless gene ig essociatad W20R anowhor Vary esteble gens. In thet case a simples biotinloss VALL never hava dean in this leboratory (to the extent of our knowledge, ) ae hould,furthasraors,ba advantassous to usa stocks of ho tsrozsnoous “ied nin tha osont that tharsa exist getlnzs types, sterility. factors, ato. would propos? to inoculate into ths sana tubs (under va zying con= ations) two uszuknus different mutants, and saacot for wild typos (0 or 100% of which should ba sarkod with biotin) by incoulating into windwal from that mixed cultura, sxperiuonts alrasdy porforasd show thé tna7rs ie. in sone casos little or no rapbd symbiotic growta couparable 30 thea k Haurospora hoterocaryons. “Ur ail investigation: of this sort has already ocourr3sd to you, -— pisasa let ma know, as I am sure that you can do a much batter job iw. nav3 better facilitiss for it toan Ison tno othor hand, if your plans do not inoluds work such as this I should appraciate vary: uuoh tho servics I ask of you. Ons further point; tho fact that a varioty of cutants can ba ootained suzs.9sta vary ctrongly that the bactorda azz (at least during £02 phase) haploid. It is possibls on the othay hend howaver thas Givloid mutant ne berozysotes could, if e sexual proc3ass exista,have & homosygous. sagr3agant in a latar zoneration. Have you eny inforaa= tion on this pointy I note that (according to your pspor) your cul- wurss Worg szzudiant BAREODXEXES inoub:ted 4 hours after. irradiation. Have you any sug,estions.as to tho numosr of gonsrations traversed in this: tine. oy your Sexetny ’ Vary sincarely yours, Jognua Lodarberg, AS. Vels USNR.