15/12/51

Dear Dr.Hayes,
Thank you very much for your letter of Decedénd 3
your discovery of the retention of fertilizing abil.ty after strep-
t@uyoin sterilizetion is very exciting and throws mucin light on
my present work, Thank you for let:ing me know it in advance of
publication.
- IT have been doing a good deal of work with strep-

tonycin letely,and,yas you will see,sc:e of my resulis are conple=-

mentary to yours in a rem-rkable way. I shall tell you abcut them,

as you may be interested to see what sort of confirmation shpough
an entirely independent approach my resul‘s can bring to yours.

I an not thinking of publishingthis soon,as 1 shsuld like to be
able to conclude on one iain point before -whether maps are linear
or not,amg unless present xsone ened will show that I aw still
very far from it 4 however,you can wake what use you like cf thés
better of mine.

Trying to follow up one of Liy aius —- thats of naking
strains which ,:n crossing,would not be heterozygous for chrokoso—
me mutation as I think I tave shown the cross 58-161 x W 677 is =
I have prepared a 5 ~161 with .ultiple sugar deficiencies ( $ 147 )
and,later,maz the following four strains + §8-161 s*; 5-151 rever—
ted to prototrophism by back mutation and selection on mininal 3
1AT s* 3 147 reverted ‘to rrototrophism. The crosses 147 s* x 58-
161/ Pash ceagent © and 147 prototrophic x 58-161 s* are both suce-
cessful on minimal plus streotomyciny they are complenentary hete~

rozygous for a number of sugars: apparently without chpomosome mu-
-tations ‘isturbing the segregations (I am not very sure yet about
enka" } point).

On the other hand, EB hiea to repeat entirely similar experi-
ments with W677 (making W 677 s* and W 677 prototroohicgand the same
on a variety of other strains,alla having in com on with W 677 the
T-L-3, - markers), the cross 2L3,-S" x TLB,+ on minimal + streptomy-
cin never gave rise to any prototroph,although several independent
streins were bessed. Therefore I concluded that while 5h—16l,as the
original K 12,behaved as homothallic, ieeecould forme male and female
gametes, strain W677 and a11/PEBS= derivatives behaved as heterothal-
lic. ,iee.coulé foru only one type of gamete (verhans the fenaleyones
after your results).

However honothallism can be restored by reconbination.In fact,
recombinants fron 3-161 and W 671/San crese. tow phgnatyee was “just
following this upp to control the inheritance of this/metins—-typ°-like
behavi-ur.

I shall keep youx informed of future i2veltments , because, al th-
uch our ‘osds are not the sane,they seem to me to be closely parallel,

As to Proteus ,1I feel I ourht to have written to you about its
but ry results were ratier uninteresting.The round bodies,which you

[However
described to me,were clefaly visible.I made an nber of »utants,none
of which seemdad stable enough to provide satisfactory evidence for
erossins, Also, 1 found a paper by Dienes ~iving evidence against it,
after work done by isotatins the round bodies and testine ther for
natural markoss. :

With all my gree:ings for Xmas and the New Year

Yours sincerely