G28) I,uU62

TRANSDUCTION MAPPING.

The following remarks were instigated by certain data in the mapping of gene
sequences in Salmonella kindly furnished for our inspection by Dre My Dems
We found that the usual trialeand errex method for analysis of multdnoins -
data was especially tedious and therefore ebterpted a move anelyuieol pi
«he seme principles may be applicable tc tetrad analysis, We postulate the
generally acceptsd modo) (cf. Symposium on Genetic Recombination, Jour. Celle
Comp. Physiol... lS, Suppl. 2) that transduction Involves the transfer of 4
linear fragment which then exchanges in some manner with a homologous region of
the recipient chromosome, Whether each fragment overlaps all the genes in ths
sequence being studied is not crucial for the following discussion, so long as
the incorporation of an uninterrupted linear segnent is the principal condition
for a frequent exchange types

  

 

Tao procedures are shown, For the more practical requirements of 3+ and he
point tests, tables are presented. A more general, but non-symbolic, procedure
is also available for hypothetical, more complex linkage tests.

A, Tables for testing transduction map sequences, 3 and he point tests.
Instructions:

1, Write down the donor genotype (differential markers only) in any arbitrary
BEQUENCE, Coffs We Xt Ye Zeaces

2. Group the experimental results into the rare and frequent classes,

3. Cede these classes as transformations of the donor genotype, The cade "a"
means "reverse the sign of the first lecus written", "b" the same for the
second, ote, Thus, (as) (WeeToZ~) would be WektYod~,

ho The table gives the codes for the mitiple exchange classes (mec) corres=
ponding to each sequence, Those models are excluded where frequently found
types are included in the mec codes, and vice verea.

5S. The sequence codes can be translated into maps by writing] W XY Zjand trans=
posing accordingly. Thus, BCAD would be the map KYWZ, ABCD

6. For the reciprocal transduction, superimpose the operation abed, so that,
@ofo, ac becomes bds c becomes abd in the mee codes.

Sequence Operator MEC types
. as transforms of donor genotype
3-point test ABC b
ACB e
BAC a
hepoint test ABCD b c as be bd.
ABDG b ad ad bd be
ACBD e b ab te 3=—s ae
ACDB e a ag ed be
ADEG d b ab ba od
ADCB é c ac ed ba
BAGD a e be as ed
BADG a d ba . ad ae
BOAD e a ab ae cd
BDAG a a ab ad ed
CABD a b be ab ad
CBAD b a ac ab ba

The complete table can be generated as the permutations of (atbecd!), where
a'b = (bto+d) b = bebered and ed! = C(aebee) © acrbore,
Be

Le

Be

ce

ext? ap

Nepolot Goethe»

 
 
   

Fer Wich
vether than th: ab (NEC) gevotwper.
(lasses with vi “LLL be sadd to have ‘
wel eonotypes in the rth renk lexcopt spans,
Sactom-transduction ard ren, which correspomis to nonebransduction).
Classify frequen’ genclypes according to revit and begin with r=l, Rank a
(comlotely Lisi t

Follow coding inet:

mewn eh te
TEC GShOYIOYULG SL

     
       

he

 

   

ad tronsduction) should be frecmenth.

Iu wank 2, there sheuld ba two types corresponding te the periphers
in ranle 2, theve should be 3 frequent types, Gne of these is the cashin
of the two peripheral Lscis the other two show the linkage of the pemul
faoterss

In vank 3, leok for the additional factors associated with she peripherals
gust established, Ignere combinations ef factors previcnsiy located,

Tn wane bh, and subsequently until all facters are iseated, reposts the same
process ac in 5S, Each rank should establish the Leeation of the nest So
fectors, starving from the perlphery of the sequence to its cenber,
Working oxample for me7?. Informative types in each ranks ave uvierlLined,

   
 

words i 2 3 h 5
feequant
tapes {SEC} a. ae eae ( } acde?
& ~~ ad aot ade? acd?s
og <= ace acte abdet

2 ande 0
_— Betz ~~» abdex
ate

Stepss
rel Aeseaed

ree £Da008G
rez &DE,.G2G Henee sequence must be ADEBOIG, and following steps are

wel, ADEDGYG to check ormby.
wah ADEBGYS

 

The sequence operator [eage, ADEBGFC) is then applied to the arbibrasy gen
sequence (VEZ...) to obtein the map order, as owblined in A-S,

ine sensideration has te Le given to the Multations impesed by the ack
methods on the varlety of genotypes that ean be detected, ‘The inadvertan
inclusion of an unlinked factor can be readily detacted by abnormalities in
frequencies in runks O and 1, Data from reciprecal. transductions can be
readily combined es indicated in Aud,

 

~

Jo Lederberg and M, Kimura, Department ef Cenetles. University of Wisconsin,

Rovember 16, 1955 For Miewroblal Genetbies Pulletin