UNIVERSITY OF LONDON

 

OF LONDON

Telegrams

POSGRADMED CHISK LONDON . . DUCANE ROAD
Telepho
SHEpherds Bush 1260 (4 lines) . ; LONDON W.12
Dr. We Hayes,
Department ef Bacteriology.

ath. August, 1956.

Dear Josh,

Thanks for your last letter, I had a very pleasant talk with Alan
Richter at C.S.H. in June where he was kind enough to tell me some ef his
and your findings in connection with an Hfr strain which segregated F-+,
I think we might have anticipated this on the Wollman/Jaceb theory.
However, he reperted me incorrectly as regards HfrH, If I gave the
impression that this was stable, what I meant was that I have never had
any trouble with my stocks with regard to reversien to F+, Hewever, I
find it easy te obtain an F+ reversion eof HfrH by serial sub-culture
in breth. Although I have had HfrC for some time, I have net yet
done any work with it. I do not have any M~SS HfrH but enly the S® 3Bi-
strain. I think you have my original strain but in case anything

6 happened to it I will send you another ciltweef this as well as the

sSBy-.

I get a reprint ef the lambda transduction paper frem Morse - many
thanks te you both. I quite understand about your reprint problems,
I just wanted to be sure that I was on your mailing-list.

With regard te the "FP- which is genetically Hfr" which you did net
understand from my last letter: we have found that if we make either
M-F+ or M-Hfrii Furacin resistant they are no lenger fertile with F-
strains but can act as recipients with TLBy-F+ or Hfr, However, in this
latter cross, they behave like nermal HfrH amtheir aerated evernight
cultures give’a much higher recombination! rate than young cultures, while
the optimal fate is much lewer than with/control Feei.e. the strains
behave as if they were genotypically doers altheugh they cannét. dénate.
This change is associated with a cha in colenial appearance and I
think it is due to a failure to conjygate with F- although cenjugation
with F+ or Hfr is still possible i,é, that the failure of wencombination
ie due te a change in cell surface only. We are now trying te carry
cut experiments to prove genet lly that these infertile strains are

still genotypically donors, . . : .
= : which uistenals Li ack to master % mabey
Se aril SE + Co He) MAES.

 
I am sorry that the Ciba Symposium does not fit in with your
Australian plans as we hoped it might

» However, we are still hoping &:
that both you and Esther will be able to make the trip,

With Best Wishes,

Yours,

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