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Letter from Thomas C. Nelson to Joshua Lederberg

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Disciplines
  • Ecology
  • Geography

Abstract

Concerning Hayes’ paper in N*ture: H,ve similar experiments been done with one parent lysed with 4 LJJ \ phage? Of course I realize that this is not strictly comparable 'G to the strep experiments. ti. Vogt was thinking of doing this I 1 c but whether she did or not 1 we8 never able to find out. t: Concerrling ~wmlli Mnccacarro in Nature - i.e., that a hi frequency of recombination Is obtained when the smermtants of the mshed cultures are mixed (concluded to be due to residuum Of non-sedimented bacteria plus growth factors allowing plate microcolony formation): a. the residudm of non-sedimented cells would grubably be single cells rather than clumps $which form when 0.9 $ is added to effect the secomd washing) hence there is a greater chance of cells of different parentage coming into contact than in clumps thus giving more recoverable progeny b. A6. Vogt, when she decided not to follow the methods I used to produce kinetics results, would grow both phrentnl strains in NB to bout 10 to the Bth, mix eaual volumes, allow dz$ several division x o occur (grow together one hour), then plate, without washing, various volumes in minimal medium, the total volume plated being l/2 of the total volume of the system which was then made up by adding fresh NE3 (in this manner she thought that the cells in the cross were being held in a steady state as r'ar as the environmental and cell coniitions %ere concerned) Obviously the recovery oi nrototrophs will be Dronortionpl>y grenter, due to carry-over of brolbth which is not used u", when ~1 larger volume of inoculum is almted, due to mlcrocolony formation and nlate recombination. In looking over Peg Lleb's letter in which she says she crossed K12 S X Kll77 I note that she has nerformed the cross both ways - by my method with the result that the wotos are >rbaortional to the nroduct of the narent concentr*tions, hnd by the Vogt method where the Drotos are proportional to the sum of the nsreata ulnted

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