APRIL 27-28-MINUrES OF MEETING 
15 
and therefore may affect tranarussibility. data are 
not sufficient, according to the "Instructions to Investigators". 
4 . Modification of Existing EK2 Plasmids to Permit EK3 Testing 
The plasnid Working Group has learned that efforts to accomplish 
modification of existing EK2 plasmids to permit EK3 testing 
are underway in the laboratories of Drs. Hel inski, Curtiss, 
and Vapnek. It is unlikely that any will be ready until 
late next fall. 
5. TheOu- Anderson manuscript : Cr . Adelberg noted that the 
claim by CXi and Anderson to have demonstrated F~ x F" 
recombination (including xlllb x E”) has been challenged 
by Dr. Norton Zinder (personal communication), who has obtained 
evidence that one of their "F " strains carries an unexpressed 
conjugal plasmid. The Working Group will defer action on 
testing criteria for xl776 x E~ recombination until it 
has had confirmation of the phe ncme non frcm Drs . Falkow, 
Curtiss and Low, who are independently experimenting with 
other F~ strains. They will look for transfer of a non- 
con jugal plasnid as well as chromosomal marker recombination, 
as a more sensitive test. 
B. Phage Systems 
The report on phage systems was presented by Drs. Campbell and 
Gottesnan . 
1. In vitro Packagin g 
The RAC at its October- Nov ember 1977 meeting had approved 
an _in vitro packaging system for use with certified EK2 lambda 
systems. The Oonnuttee had specified criteria, including UV 
irradiation, that must be satisfied for each packaging extract. 
Dr. Gottesman discussed the requirements for in vitro packaging 
systems for lambda phage reccmb inants in the light of ccnments by 
several investigators that UV .irradiation should not be required. 
The RAC felt that UV irradiation need not be a specific requirement, 
and adopted revised criteria (Attachment VI). A statement on 
verification of safety features in EK2 vectors bearing cloned 
segments was also adopted. These requirements will be published 
in the Bulletin . 
2. Modified AgtWES.AB 
The Committee reviewed a request from Drs. Bell and Rutter to 
use a modification of Ag tWES .AB as a certified EK2 system. 
The EK2 vector has been slightly modified so that segments 
can be joined by dA-bT tailing and thus obviate the need to 
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