Genetical Research

Short Papers

I-like resistance factors with the fi+ character

June N. Grindleya1 and E. S. Andersona1

a1 Enteric Reference Laboratory, Public Health Laboratory Service, Colindale Avenue, London, N.W.9


The fi+ (fertility inhibition+) property was originally described in R factors related to F (F-like factors). The original fi factors, in contrast, were related to the transfer factor of a colicin I factor (I-like factors). We describe here a group of R factors which are fi+ but I-like. It is suggested that all the terms fi+, fi, F-like and I-like be used in the description of transferable plasmids.

(Received February 26 1971)