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The Joshua Lederberg Papers

Letter from Thomas C. Nelson to Joshua Lederberg pdf (511,198 Bytes) transcript of pdf
Letter from Thomas C. Nelson to Joshua Lederberg
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Nelson, Thomas C.
Lederberg, Joshua
Courtesy of Joshua Lederberg.
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Lederberg Grouping: Correspondence B
Box Number: 7
Folder Number: 220
Unique Identifier:
Accession Number:
Document Type:
Letters (correspondence)
Physical Condition:
Series: Correspondence, 1935-2002
SubSeries: 1947-1953
Folder: Nelson, Thomas C.
Dear Josh,
The people who have come around for your strains are the P[?]:
Margarite Vogt (Delbruck's person who has been attempting to repeat my stuff) for 679-680[?] because her nutrient agar counts don't correspond to results on leucine theorine supplemental medium (mine do)
Derels (sp?) Rowley, ex Heming's lab ex Heidelberger's lab, [ . . . ], medical bacteriologist. He is looking for penicillin [ . . . ] - - normals are resistants to him (50 00/ml v7 0.001--0.100/ml). He has surveyed all my stocks -- your Y strains (all 2X+) W1205 all my 2- strains and [ . . . ] none but has [ . . . ] by two Rj. Screening OV plage -> NH + bacteriostatic (to sensitives) concentration of penicillin, let grow, marks for the resultant normals, enough out penicillin with penicillanose, re incubate, new ones are pen sensitives unfortunatley he gave them to me to test for auxotrophic requirements, one is and one isn't, and both
are endo negative (i.e., not merely lac- but non-growing completely).
are endo negative (i.e., not merely lac- but non-growing completely). Vogt gave a private talk on her work - she is attempting to find out when the zygotes are formed by killing the strep[?] sens parent and zygote by strep[?]at different times after mating. Unfortunately a) her methods are somewhat mixed up - - she grows the strains together in nutrient broth "in oscillation"-- i.e. 108 -> 240t/ml, adding to 1 ml fresh nutrient broth -> 1x108 and start all over again (no controls to show cells are in log phase continuously), dilutes in phosphate buffer 1/10, 1/50, 1/100, 1/200, 1/500 and plates in minimal [ . . . ] medium (washed agar but differential carry-over of nutrient broth whose growth potential is not exhausted and she wonders, 1) why dilutions don't correspond, and 2) why prototrophs keep appearing at 2,3,4 days) with and without strep. In S+ plates only 10% of mates in S- plates pinning her down dictated the part that her figures on the board given in prototrophs /107 cells, as 50, 240, 4120, etc represented respectively 2, 5, 160 colonies. She gets no increase with time that they sit in minimal medium on the plates before she layers - 0,1,2 hrs being used - hence
believes that "sensitization" occurs (they are trying to bring her around to believing that the real affair is segregation). That is about all I can make of that.
As for 2+ 2- I'm working on the biochem with powdered[?] cells. The genetics is screwey[sic] but as ff[?]for geneology[sic]:
1) all y stocks tested, and 679-682, 58-161, are (by serial reversion tested of prototrophs) capable of growth in or on pemerate[?] and malate hence are S+ in phenotype since they may represent several loci I call them 2X+, i.e. Y53 is 2Y53+, 679-680 is S+670-680
2) Ryan's K12 from which we prepared auxotrophs is 2-,i.e., incapable of growth in pemerate and malate.
Adapted from 2)
3) Once and only once an adaptation to the 2+ condition occurred -So+. A diaxotroph - S+lax = (histedone alarine) was prepared from this.
Now as for crosses:
2+x x 2+x (1/53 x 1/24 /n instance) give only 2+
2- x 2- give only 2- *20+ x 2- give mixture of 2- x 2+ (unless cross is made directly to K122- on pemarate[?] to select out only 2+)
20t x 2xt give only 2+
2x+ x 2- give mixtures of 2- x 2Xt * formerly only -30 prototrophs and only 1 cross were tested and all were 2+ now in other crosses, 2+ is also thrown[?]. Incidentally -- is the lac- marker in y53 laex? And does it segregate independently in crosses with 1/24 b I found it to do so - also with s+lx.
[ . . . ] have N1177 and will try crossing directly with S+. Oxide was dt. - I have several a meth types . One Agu be which wouldn't cross by z+ ( at least no 2+ wre thrown). On Agie is mucoid colony form same locus on closely linked with other Agre non-mucoid.
Further works on 2+ will be besides[?] biochemistry -- survey of other peoples' k12 and dominance test if I can squeeze out a het - should be dominant, that is, 2+ > 2-
ya I have been using in isolating single putative zygotes - By fission using 2 sets of markers one for screening the other for determining cross-over relationships. Of course I can recover only one "strand" little data on this yet - the experiments get too big 400 tubes minimum. To see whether zygotes are formed immediately [TABLE] in liquid or later[?] I have used OU assuming sensitivity of zygote would be less than parentals if killing by lethal induction occurs (probably doesn't). Of course there are troubles, differential killing of parentals (controlled by plating for totals in medium in which one parental gives large, other small colonies) screening in clumps buffering causing release of mululites[?] (added previously irradiated parentals in reconstruction.)
My data are few but the accompanying graph gives an idea - times are mixing times previous to OV - concentration is 10X at best haven't carried killing down too far, no protos left.
In agglutination I've been trying to reduce isoagglutination in culture tubes and wishing prior to mixing and increasing hetero-agglutination on mixing -- not much luck.
Thanks for the rain check offer - I may take you up on it. There was a possibility of a position at U of W in industrial microbiology but it fell thru. We are applying for a UAF to stay here next year. As expected my fellowship was only extended thru the summer. Maybe I had better investigate gov't jobs - the draft age is being increased.
Tom C.
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