The following is 0 true copy of my notes, Yolume III, labelled “Summaries” which were recorded during the interval 1951-1956 while | was in the Lederberg laboratory in the Department of Genetics at the University of Wisconsin in Madison. The notes were entered in intervals with some pagination and represent various types of summaries, speculatiuons, etc. | have numbered them sequentially in the upper right hand corner from page 1 to page 253 for convenience. There are a number of irradiation experiments (UY) plotted which have never been published. | remember communicating some of them to E. Kellenberger who may have giventhem to Werner Arber since | believe there are some similar experiments in Arber's doctoral dissertation. There are also some drafts of my own disseration. Items of possible interest are the handwritten notes of J. Lederberg (4/10/54) labelled “Remaining Questions” on pages 90-92; the typing bill for my disseration, page 155; 4 status report of the Lederberg lab for 1953, pages 161-195; some notes of JL on putting the stock book on keysort cards, page 197; a matrix by JL for transduction mapping, page 201; and an index to Volume I! of my notes, pages 202-206. This Volume is a hodge-podge and doesn't represent any temporal order - | believe page 253 is really ahead of page | which was a preliminary report leading to my dissertation. WA re M. L. Morse Webb-Waring Lung Institute University of Colorado Health Sciences Center Denver, CO, 80262 November 20,1986. . Summaries Research aM. L. Morse Gene tics Materials and Methods The principal cultures used are listed in table 1. In summary they represent three distinct matatd ons which lead to the loss of ability to ferment gakactose (Lederberg, F., 1950). The Gal,- and Gal,- stocks are the result of a single mutation to (-¥ in each case, while the Galo- stocks represent two independent mutations te (-) whose identity is based upon the observation that no(+) recombinants have been observed in more than 11,000 prototreophic recombinanta from crosses between them and upon the syiotyscus behavior of the stocks in transduction experiments. These three loci are closely linked to one another as indicated by the data in table 2, but the order of the loci is not specified. In addition, each of these loci is known (Lderbberg, E, and Laereberg, : J., 1953) to be closely linked to the Lp or latent phagé locus of E. cli K-12. Three alleles are known to exist at the Lp locus; (1) Lpt+t, overtly lysogenic and showing evidence of free phage in cross brushes with Lp® forms, and resistant to lysis by free lambda phege, (2) Lp™, not overtly lysogenic and showing the presence of free phage in cross brushes with Lp® forms, but resistant to lysis by free lambda phage, (3) Lp®, not lysogenic, and being lysed or lysegenized by free phage. More extensive delineation of the interrelatiouship of these loci has not been feasible until recently and it is hoped that with the aid of a new method of di‘ti neni shing the minus recombinants that mapping of this region may be accomplished. . Another lecua which has a direct bearing upon the problem is the locus contolling resistance to lambda~2, the lytic mutant cf lambda. This locus, Lpo, © has an epistatic effect upon evente controlled by Lp (Lederberg, E. and Lederberg, J., 1953). Thus a change from Lp,® (lambda-2 sensitive) to Lp", (lambda-2 resistant) results in a loss by the cell of the ability to adsorb lambda as well es lambda-2. Sensitivity to lambda by a cell therefore can be nasked by the presence of the r allele of Lp. The Lp, Locus is not clesely is—net—etosety linked to either Lp or to any of the galactose loci in question. Methods of cultivation and media used were as detailed in Lederberg, J. (1950). Liquid cultuivetions were in penassay broth medium, with or without added aeration, solid media used were of EMB base, either with or without added suger, or for crosses, @ synthetic form of EMB, EMS wae used. . High titkered lysates of cultures were prepared after tho method of Weigle and Delbrtick (195 ) by inducing lysia of penassay eon cells by means of irradiation with small doses of ultraviolet. The UV was adinistered to saline x suspehsions of the ceils and the cells subsequently diluted with 2X penassay broth and incubated wigh aeration until maximal clearing was obtained, Lytically grown lambda was obtained by infecting the sensitive cells by exposures to lambda prepared by the Lwoff technique, discarding the superia~ tants after the adsorptions ang resuspending the sedimented celle in mtrivnt saline broth. The NSB suspensions were then incubated wth aeration until maximal clearing was obtained, Table I List of pertinent cultures Culture Genotype w- - i ? W518 FM Lac, “Gal, Lp) *Lpo® =f, - - + 8 W750 FM Lac, Gal, Lp, Lpo well F'WLac, Gal, Lp,” lB, W902 FTL Th” Gal,” Lp; lp, W1210 FM Lac, Galo Lp) Lpo W1436 FT L-th"Lao, “Galy-Ip, *Lpo® w1924 FM Lac, Gali, Lp1"Lpo* +> on, >. W2175 F gal 2 Lp} Lp,° . . ie . w2281 ¥ M Lacy Galg Lp, “ipo - + W2342 F*Lac) “Gal"Lp, “Lp,® W2373 FH st"Leuc"Gal, “Lp; "Lpo® Table 2 Recombination between the Galactose Negatives Cross Minimum Number of Percent Prototrophic Recombinants (+) Recombinants FY Gelj- X FGal,- (1) 1500 0.13 o*@) (2) 65197 0.06 exe) (39853603 0.027 11620 . 0.06 F* Gal,- X ¥Gal;- 4588, os, 0.13 tye FA ¥* Gal,- X FT Galg- 2654 str 0.23 mounts of Results yard 0 af wild tena cultures are mixed with Galj-, When high titered lysate ae Galo- wat Gal; cells ani plated on HS galectese medius, results such as those in figura a are obtained. Since each of these mutations te gal- is capable of reverse mutation tne data shown in figure 1 have teen corrected for the number of reversions by subtragting tnis number as determined fram cantrol platings with no added lysate. Figure 1 chows that with increasing amounts ef added lysate thers is a Lixnsar increase in the number of galactose fermenting papillae per plata, In addition, figure 1 indicates tnat lambda sensitive cultures appear te be more capable of showing the effect of added lysate than lysogenic cultures of cultures carrying a nen-pleque-forming type of lambda. When lysates of gal- cultures are mixed with the various gal- cells and plated upon galactese medium results similar to these shown in table 3 are abtained. Each of the lysates of the gal- is capable of evo-iug galact-se fermenting papillae uppn plates spread with the other gai- cell types but not with plates spread with cells of its mvn type. The adility te wekneduce galt Clones in other gal=- bat not with cells of type corresponds te the differentiation ef thease gal- mutations dy PVecotibinabiaual analysis. Evidence ceuplemenating this ia ahown in table 4 which shews that the ability tr evoke papillae with cells of type is restored by reverse mutatinn. Presumably phenotypic reversicus can be at two types, reverse mutatic-n at the mutated lncus, and mateation ata gecend locus whose action waimicy tie actiru of the first gene. Reversians of this second claas should not be able to evote papillae frem cejls of type. Such reversions as the latter have unt as yet been investicated. - Pable 3 Interaction of Gal;-, Gal,- and %al,- e Gal,- Gal5- Gal,,- Wild Type miter (x10) - 2.42 4.9 12" 1,4 Cells Gal,;- Lp* (1) ge - 176" 43 a (2) 2 2 - - 405 Galo- Lp’ (1) ib 52 ll 43 - (2) 20 - 10 - 356 Gely- Lp* (1) 89 - 202 - 7 (2) 50 85 - - 417 (3) 47 - - 50 394 * Number of pepillae per plate, 0.1 ml lysate plated. Between 10° and 107 cella plated Table 4 , Restoration by Reverse Mutatian of the Ability to Transduce Previously Nontransducible Loci Locus 7 AdaSti on fall by) Reversion _None Reversion Lysate Gal,- Gal,* #1 0 6B | Gal.- Galg, #1 10 96 Gal, #2 6 552 Gal,,® Gal,” #5 39 204 Gal" #8 25 291 * Number of popillaeoper plate, 0.1 ml lysate plated Between 10 and 10 celle paased. @ Examination cf the other characteristics of the cells transduced to gal (+) by lyeh&’e exposure has uniformly shown no changes in any of them with the exception of the induction of lysogenicity in the lamada sensitive forms. Direct attempts to transduce other factors have been uniformly negative. A summary of the avilable data is given in table 5. In connection with the negative results in attempts to transduce xylose and lactose loci it shruld be noted that both xylose and lactosd containing media have some selective value for galactose ferganting clones. . Transduction in K-12 thus far haa been found to be limited to several galactose loci closely linked to the latent phage l-cue, Lp. These loci include Gal), Galo, Galz, Gal, Galg, and pessidly several more that have not as yet been Classified. The experiments reported here will concern obly Galj, Galo and Gal, although some observations on Gal; and Galg have been made. Hot ali loci contmolling galactose fermentation are transducible. Cne occurring in W2312 will be mentioned later, and another induced by copper treatment by Helen Byyers hag been found. The transductions described above have been effected by means of lysates perpared by the Lwoff technique of inducing lysis with a small dose of ultraviclet. Lysates prepared by lytic growth of the phage on a sensitive culture apparently have no transducing activity and have lost the transducing activity {ncluded in the inoculum. The inability of this type of lysate to transduce is demonsgrated by the results given in table 6. The necessity for lambda adsorption for transduction is illustrated by the results given in tavle 7. When the various gal- are found coupled with the F allele of Lpo, a conmblaskion which is incapable of adsorbing either lambda oF lembda-2, transductions are not observed. The presence of this allele of Lpy does @) not interfer in the capacity of a culture to give rise to &ransducing lysates transducrele aud the transducibdility of a gal- locus found coupled with Lp." ia demonstrable when a multable cross is made and a gal- Ip,” recombinant obtained. Recovery of the transducing activity of a lysate by the method of mixing lysate and cells on plates appears to be gool in the case of lysogenic cultures, the variation being less than two-fold over a thousand-fold change in the number of cells plated (figure 2). This is not the case when the added cells are lambda sensitive, the variation beiig in this a twp or three-fold greater over & similar range of cell concentrations. It should be noted again that t he lambda sensitive cultures give approximately ten-fold or more transductions at any cell densitiy, and that +H@%, the relationship of the activities on the two types of cells 1@ not known. the ratic of number of transductions to phage content of the lysates approximates 107? for lysegenic assay cells, about 1076 for sensitive cells, imtziztaxrizree Alternatively to mixing cells and lysate on plates the transducing activity of the lysates may be adsorbed upon celle and the cells then plated out on agar. Table & gives some indication of the adsorption of the transducing activity and also some indication of the adsorption of the phage under the same conditions. ranie gi | ee Effect of the Lp Locus on Transduci bility i Y dy tt eer Galactose Locus ig Addi $i on “Wilda Type Lypate Gali- Lp), Lp2® 1* 426" Gal,- Lp) Lp2 1 2 Gal,- Lp,* p,* 20 356 GalS~ Lpy* ipet 14 | 14 +. 8 Gal,- Lp, LPo 89 296 Galy- Lp,’ Lp5” 50 5? * Numbers of papillge per plate, 0.1 ml lysase plated Between 10° an 10” cells plated. rane #S | Other Loot tested but not found Transducible | - Locus _ Bamber of Experiments | Valtures Invokved __ Lac, 4 . W112 (ser or glyc) 1 W1678 Leuc 3 W1736, W1436_ Methionine 4 58-161, W811, W1821, W518 Xylose 3 W1821 s 1 W518. Prol ” W1692, W1920, W2062 Mal 1 W2071 : Hes, bom) | Table Action of Lytically Grown lambda in Transduction Seren Culture Mo Adgs ton lytic Lambda Lysate(2.4 x 1070 lambda/ m1) 228 _ W750 w 518 9 : 3 W2175 7 8 239 W750 2 0 - W518 13 8 W2175 6 2 254 W750 - 3** w518 - 6%" W2281 - g** W2373 - 6** W811 - 39%* erg of papillae per plate, 0.1 ml lysate paated. "0D 108-10 cells plated. re: *, es these peprilae picked aud streaked out all fouud - stable . WE pete” \ adsoeed om WitEE pol F wo foe Chpotnres. . Cabs Jeng laws with Gerahn . Carpe flee cotchD Fuh cotly Gren \ as fps dul yes ua gunned m NSB. Ger ted tr but etpoied Crthy . MASSACHUSETTS. NORWOOD, (NC,, > z < a = Oo v9 x oO Q a x wW Q 9 y BY FOUR CYCLES RATIO RULING, 4120 DIVISIONS) INCH PER 20 DIVISIONS NO. 32,226. PRINTED IN U.S.A. 2000 9 1000 ayetg dad ae[tideyz JO raquay Number of Cells Plated fable 8 Adsorption of the Transducing Activity from Lysates Adsorbing Phage Cell Percent Adsorbed Cells Titer Miter dst Ads. 2nd Ads.* 3rd Ads. X 10? X 107 Phage _ ‘Trans, _ Phage Trans, Phage _Trans. Galy- Lp*® (1) 2.5 0,71 60 79 50 41 16 46 (2) 3.9 0.55 52 33 - - - - Galy- Lp’ (1) 14 c. 10 - 79 (2) 18 16 - 72 - 56 - 0.0 (3) 14 ce. 10 - 97 - - es - Galo~ Lp” 18 6 - 35 - 33 - 0.0 Gal,- Ip* 18 6.5 = 45 - 100 - —00 * The supernatant from the first adsorption was decanted and an equivalent volume of fresh lysate added. Similarly for the third adsorption. Assays were made of the amount of material remaining in the supernatants. Titers given are for the phage-lysate adsorbing mixture. Tu the eLpevimeuts tuuelwiua, GCotg- Les GSIGy of the Sediment wast wéde Same wns tauces, Teh recavevy in freve Cotes Wor Mu tian loo - presumably be te. (ck Kaot wht achuh wos uudeveshwafed by me use of bre due oO (eu O55 OH cetls - Some of the papillae evoked by lysate exposure have a property which distinguishes tham at once from Spontaneous reversions. That is, they are unstable for galactose fermentation and segregate (~) cells ‘over many single colony transfers. The mature frequency of unstable transductions and the nature of the segregants will be taken up in-a later aection, {t is necessary to mention them now in order to consider the realtionship betwoen the transducing agent and the phage lambda. It is also necessary at this time fpr ad to mention some spectal coltures encountered during the analysis of the segregants mentioned above. These Spebial cultures are notable for the fact that they give rise to lysates by the Iwoff technique in which. the ratio of transduction activity te lambda plaque forming activity is much elaser to unity than is found in the usual cultures of K-12. These cultures will also be considered in a later section and it will suffice to say here that exposure ef a population cf gal- cells to one of these lysates can result in the transduction of several percent of the cells to galt. The data in table 9 indicates that when lamda sensitive cells are transduced the resultant cells and their gal~ sogregants heve for the most part become lysogenized. When Lp," forms are transduced thay also may become lysogenized, but much less frequently than sensitives. Hewever, these results may be misleading since the platings involve large quantities of i and it cannot be certain that lysogenization was not prior or subsequent to transduction. When the transductions are made with the special lysates mentioned above, Besults such as those shown in table 10 are obtained. Under conditions where one percent have been of the cells uum transduced to galt+ the transductions have become lysogenized, the same or Lp,’ , while the gal- cells in thts environment have remained lambda sensitive. , Table 9 Correlation of Lysogenization with Transduction © Locus transduced Lysate _ Transaducti ons . Segpangants _ Sad Lp Zonotype squrce Humber Percent Lp; Sumber Percont Lp, 7 @al,- tp,° wild 23 87 1 100 galo~ 24 95, ? 100 gals~ 12 58 0 - BAL 22 7 9 100 Galo- Lp," wild 13 85 13 85 | gal,- 20 95 20 95 galy- 23 100 23 ~—«- 100 wild 18 100 ~ - wild - - 28 59 gal,- - ~ Ady 86 galy- - - ko 83 Gal,- Ip) > wild - - 18 100 galo- - - 19 100 gal,~ - - 45 100 Galh- wy wild - - 29 3.2 galo- ~ - 18 5.5 Totals . 154 86 267 89 Table 10 Correlation of Transduction with Lysogenicity Using Lysates Giving a High Frequen Transducti Cells Post Number of Colonies Observed Exposed Exposure - to Cell Titer Gal- Gal+ Gal- partially lysed Total Broth 4.1x 10” 3280 0 0 3280 HF? lysate 3.5 x10? 2801 31(1.1%) 5 2886 ¥ titer = j.axtot 4 gieques pev ml. Table 10a inati on Colonies efter HFT Lysate gure Colony Number of Numbers, of Colonies of Fach Clase Col Examin Ip*® Lp Lp* Gal~ . 31 31 0 oO Galt 26 | 0 23 3 The occurrence of stable transductions among the various combinations of transductions possible is indicated by the data shown in table 11. With but six exceptions the difference between expected and observed fequency of stable gal (+) on the transduction plates is sufficiently great not to require statistical treatment. In setting out this data 1¢ has been asspmed that the only source of stable (+) on the plates is from spontaneous reversions and that the use of a no lysate addition plate as an indicator of the mumber of spontaneove’is adequate in this sense. It is notable that transductions _ duvolving gal, and gal, are nearly all stable and it will be remepered that lysates of these cultures have less papillae promoting activity upon: one * another than, ‘other cultures. These two loci are readily distinguishable oa crossing test and by use of the HFT lysates mentioned above. In the other combinations of transductions possible stable transductions occur, varying in frequency from less than one percent to more than 50 percent. The segregants from the unstable traneduetions adn be classified for locus by three separate methods: (1) by the 1 lysate by which they are not ‘transduced (transduction test), (2) by that Locus which cannot be transduced to (+) via a lysate (lysate test), (3) by allelism test in crossing (crossing test). In classifying the sggregants 4t will be convenient to refer to the origin of the locus by specific termf. Euterxhuuptypitexwtiixhexeitexs By homotypic will be designated the locus of the cell tranaigpduced to (+), by heterotypic will be designated the (-) locus (if any) of the transducing lysate, and by homo- heterotypic will be designated cultures with the loci of both trasifjduced cell and transducing lysate. | Since the order of segregation fram a transduced cell can not be specifie without micromanipulative means the analysis of segregants from a single transduction in its absence is without great significance. However, the data in table 12 indicate that a single transduttion can give rise to all three types of segregants, homotypic, heterotypic, and homo-heter otypic, fi ; Table # e Occurrence of Stable “ransducti ons ell Mumberss of Stable transductiangs Genotype ABZ : Seurce of Lysake - Wild “ype _Gal,~- Geio~ Gal yw 53-8 Gal -ip,® 1/93 1 = =O 0/56 201/30 289 #4 Gi) 130 oe § 6 49° Lp,” 1/46 2- @ - - - 1/92 0+ = . 26) 3 iS 234 weipyt ys4e = = YM 4 = = 12/27 27 a3(S4) os FF at’ 1:8 Galo-"Lpy® 0/46 15 0/214 27 - -«- - ~ 0/98 4% wee Se eT $ : ‘ 32.6 “Tp? 17/248 21- 14/83 61 - = - = 14/79 52 rH) 410 | Set > b tpt WB 6> 2/65 0- = = = = 5/56 0- +CS)M tH ‘ 4f.1 Gal,- Lp,* 19/835 383 29/72 72 11/472 20 4/128 22 - « FEES 07 set 9° Lp,* 41/573 133 51/96 96 - = « - - -« 224(976 67 3 50. “Ep, 31/320 127 = - 31/238 50 - - en qu) se Set u Exp't = number of stable expected no. papillae control no. papillae lysate plate Cbs. = number of stable observed = Ho. stable observed x no. papillae fransd. Reorder no. pap. in sample Note: A number of differeut lysates were employed. In the case of Gal.~ lysates, the first columa represents lysates of ¥902, the second column, W12I0. In the case of the Galj~ Lp, cells, the first is 4750, the second #2343, a prototroph derived from W750 @ Table 12 Segregants from a Single Transduction, tested by Transduction Test. The sequential ord the s 8 unkn Cell Lysate Classification of Segregants Genotype Source Homotypic Heter is H heter ic Gal) Gal,- ~ 2 1 & i but it can not be stated that the sceragpt one jin any sequence or if sequential. fhe analysis of single segregants from a large number of tranéductions was undertaken to clarify thie process. In the initial experiments the transduction tests were performed by mixing a portion of lysate from a culture of specific locus and the culture to be tested upon EMB galactose medium, but after the Av TRO discovery of the HiT lysates test for allele was by cross brush with lysates of this property upen the same mediun. , The results of _a-iarge-sunber of tests of segregants by transduction test ‘ts given in table 13 and a summary of the cultures in this table which were also tested by lysate test is given in table 14. The agreement between the two tests was complete, that is, a culture classified by vin first method as gal,- was also classified xy as this locus by the second testy A summary of the segregants which were tested by all three methods of determination 1s given in table 15. Agreement. between the crossing test and the other two tests was also complete. Some indication of the distribution of the segregant types, as judged by transduction test, can be obtained from the distribution data given in table 16. With regard to the crossing data given in table 15 4t will be noted that no crossing data for gal,~ scgregants ts reported or crosses of heter otypic segregants fron gal, transductions by gal,~ testers. Thistm because a suitable stock is not yet available. W2373, a hist” leuc™ gal,- made by transducking W1765 to gal,- has not been found “sufficiently fertile in crosses with mothe stocks te warrant its use. A new T"L~B,~ (also Het) gal,- aleo made by tranaduction to (-) may prove suitable. It should be noted that the number of protetraphic recombinants given in table 15 is probably lew by as much as 25 percent since in many instances only the smaxxexut plates with the smallest number of prototrrephic recombinants were counted in maxx experiments involving many replicate plates. j= Table 3p Analysis of Sezreeants by Transduction Assay. Summary, Nature of Type of Segregant criginal Homotypic"™ Heber otypic** Homp-heteratyoict*® Total . Transduction a Wild type on Gal~ 169 0 0 169 Gal~ on Gal- __240(85.4) 37(13,2) K(1,4) 281 809 (92-0) 37252} 4£6,88)} 450 4o7 * having the @al- locus of the transtinduced cell ** having the Gal- locus of the transducing lysate *** having the Gal- loci of both transinduced cell and transducing lysate. Table |4 Analysis of Segregants by Lysate Test. Summary. cher coment bptween Lysate Tests and Transduction Tests was Complete Nature of the original Homotypic Heterotypic Homo—heter otypic Total Transduction Wild type on Fale 21 0 0 21 Gal- on Gal~ 39 Iq 0 58 o If 0 74 Table \< Summary of the Analysis of Segregants by Transduction test, Lysate test and Crossing test, original Number of Classification by Transduction Segregants Transduction Lysate Crossing. test test test _B Homotypi Heter ot : How (+) Tot. Prot. No.(+) Tot. Rrot. Galo- --x Galy-Lp® 5 (1) Galy- Gal,- 0 2786 3 3183 (2) " " 0 2675 2 3471 (3) " " 0. 3485 23 5342 (4) " " 0 5952 1 1665 (5) " 8 0 5000 1 891 2 (1) Galo- Gal,~ 7 - 3102 0 1988 (2) " " 10 364 0 1187 Galo~ --¥ Galy-Ipt 4 (1) Galy- Gal, 0 16104 3. 1389. (2) “ " 0 $730 1 164 (3) * " 0 3358 0 202 (4) n 5 0 12848 1 171 art 3 (2) Galo- Galo- 1 11200 0 827 (2) a “ 6 10608 0 718 (3) " . 3 5000 0 hog _ Wild —=x Gal,-Ep® 4 (1). Galo- Gal 0 7805 N * (2) 8 ee 9 4992 (3) : " 0 106 (4) " a o 4552 N wala =X Galo-Lp* 4( 1) Galo~ Galo= 0 4070 (2) " " 0 5384 (30 " " 0 2072 (4) " " 0 6988 ‘Wild —-x Galj-Ip$ 4 (1) Gal Galy- 0 896 (2) 4 « 0 918 (3) " " 0 1134 (4) " " 0 863 @) (6 Table £1 Distribution of the Segregant Types by Transduction Assay Transinduced Source of Lys&&e cell Wild type Gal, Gal,-(4992) Galo-(W1210) Galy= Gal,- Ly” (W2343) 1f Gal,- = 18 Gali, 5 Galo- ~- no seg. found . Galg- Lp "(W2175) 20 Galj- 14 Gal~ - - 8 Galo= Pi ~2 Gal mo... 7 Gal) {2 Gal) —Galo-~: Lp}*(W1210) 15 Galj- — 19 ,Gela- - - oGai-- Lp,” 16 Galo>- = 20 Galo - - 21 Gal,- - 1 Galy- 1 Galo~Gal,~ | a Galj- Lp,* 20 Gal,~ nsf 16 Galy~ - - Lp,® 13 Gal,- naf 18 Gal),~ 17 Gal,- - 3Gal.— 2 Gala- Lp,” 29 Galy- nsf 15 Gal, - = usf = uo segregahts found SS Cultures giving lysases with the HFT property have been prepared for each of the gal- loci which have been given consideration to date. These cultures have the common property that each is derived from the transduction of a gal- culture by a lysate of gal,-. It 1s not known whether the transductions themselves of this type are capable of giving rise muty to HP? lysates cr uot, but the HFT stocks thus far obtained have been segregants from such transductions. Whether the transductions of galg- by other cultures gives rise to HF? segregants is not known, but one instance “la which the transduction of gal,~by gal,- resulted in an unstable (+# which had RFT preperty WOT HERA has been encountered. Sone idea of the frequency with which the HFT occur can be obtained from the following. If the case of transductions of pire gal, - by galo-» out of 28 gal,- segregants examined 4 had this property and of the heterotypic gal,-,one out of five examined was HFT, In the case of transductions of gal,,- by galo-, of 31 gal,- segrexgauts tested one was HFT, while of the three hetero- typic galo- tested one was HFT, In the above tests segregants which had been purified thr ough several single colony isolations were used. Since the HFT cultures segregate NYT. lines it is possible thattthe above estimatious are low. Attempts to obtain (+) cultures with HF? preprty by reversion of (-) have been unsucesyful in the limited attempts made thus far. This ton may be in part due to the fact that the HFT cultures segregate NFT Lines “since it was not known at the time of examination that this was the case anf the NFP reversions obtained could well have been from NFT components of the culture. The conversi-ny of a HFT culture EFEsHK to NFP is fairly rapid and the HF? cultuees are easily lost. On one occasion it was noted eA a@ culture which had been on stock slant only a few weeks had changed such that of ten colonies tested 4 were found to be MFT. The NFT cultures which remk are derived from HFT lines have not been investigated except in ime instancey, In addktion to NFT property (or possibly no activity at all) the segregants were inne case asmabire sgere Nope ne-faamennich UEEp wees demigted ant im qmwe otter iumimsre fury ware of a gal- type which was not transducible except by ax a lysate of an unstable gal(t+). In one case ( and the negative results in the other cases can possibly be explained > by the contammation of the HFT cultures with MFT cella) KA}°SX gal (+) reversions of an HFT culture were found to be unstable for gal(+) and segregated (-) which were of the same (-) type as the reverted locus. The examinati-n of more HYT cultures to to determine the relati-nship between duplication of certain loci and HFT property aud id in progress. | The lyeates of the HFT stocks which have been prepared thus far have not had high phage titers alth-ugh they have been prepared in a manuer which gives high titered lysates in MFT stocks. Whether this indicates a lower yield per bacterium of plaque forming particles or different conditions for induction is not known at the present. Preliminary experiments to determine the yield of HFT particles per bacterium are regarded with reservation since the purity of the culture with regard to AFT cells was not known. The HFT lysates have been used principally for allelésm tests. Transductions can alse be made via these lysates and the resultants studied. This has not been carried very far. The data in table 1% indicate that transductions by HF? bysates are not appreciably different from those of MFT lysates as regards occurrence of stable tramsducticns and distribution of segregants. The HF? lysates can be used for transduction from gal(t+) to gal(-) and have proved of value in creating new stocks. Table 18 lists some of the information available on the stocks transduced to (-). Since the completio: of the table gal)- and galo- Lp® o-LB,~ Ret Shave been prepared. The (-) stocks prepared thus far have been made starting with Lp® cultures. The resultant cultures may be Lp&, Lpt or Lp. In geueral the procedure has been to miy HFT lysate and cells on FMB(O) and incubate for 12-18 hours and then to streak out the growth and search for gal (-). on other occasions examination of single colonies from cell populetions exposed to HFT lysate has been used. Table 1p Transduction by HY? Lysates. “isbribution of the Segregants by Transduction Agsay Transinduced HYT Lysate Cell Genotype Gal,- : Galo- Gali- Gal,- py - lofali- 9 Gal,- 2 Gal, 1 Gal,= Gal,~ Gal- ip,” s Galy- : 8 Gel 27 an ae 1 Galo- Gal, - “15 Galy~ - Galy= by” not done * oot of & total of 18 transductions ( cr transductions and spontaneous papillae) analyze. The difference between the number of segregants reported and 18 represeats the number of stable papillae observed. © Table ( 7 @ Traneductions to Inability te Ferment “alactose Culture x Ip, ' Galactose “esul tant Transduced Genotype Locus Transduced Lp; Genotype Comment W1L85 Lp8 Galore Lp* or r 8 distinct (-) obtained from single colonies ? 2 distinct (-# obtained Galj- + ani r 2 distinct (-) obtained ¥1673 Lp® Galo + or - W1765 Lp® Gal,- 8 - W2252 Lp*® Gal, - r? 2 distinct (-) obtained Gal,- r 2 distinct (-) obtained