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CCIP4SJMBER 27
This Week’s Citation CIasslc~_______
Campbell A. Sensitive mutants of bacteriophage A Virology 14:22-32, 1961.
IDepariment of Biology. University of Rochester, NY]
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Leupold on thermosensitive mutants of
Neurospora and E co/i.
In my new position at the University of
Rochester, I decided to isolate enough suppressible A mutants to exhaust the complementation groups accessible by this means
and to carry out several tests of the basic
ideas Edgar and I had discussed. First, I
wanted to show that mutations rendering A
sensitive to extreme conditions (high temperature, high or low pH) would generate
the same complementation groups as the
suppressible mutants did. Second, I wanted
Allan Campbell
to verify that some bacterial mutants
Department of Biological Sciences
isolated for their ability to suppress a
Stanford University
bacterial gene would allow the phage
mutants to plate, as C600 did Third, I
Stanford, CA 94305
wanted to identify the function and product
of at least one such gene. For this last purJune 11, 1985
pose I chose lysis and endolysin. When these
goals had apparently been accomplished, I
In 1957, while working at Cold Spring Har- published the results. My success in exhaustbor Laboratories, I accidentally found that
ing the complementation groups proved to
two small plaque mutants of phage A isolat- be incomplete. I found 184groups; 7 more
ed on one substrain of Eschertchia colt K-12
have been identified since. After the work
(C600) failed to plate at all on another K-12 was completed, I returned to my studies
strain (W3350). During the next two years, of prophage integration and specialized
first at Cold Spring Harbor and then at the transduction, for which the mutants were inInstitut Pasteur in Paris, I isolated a total of valuable.
15 such mutants from mutagenized A stocks.
The paper has occasionally been cited for
They mapped in widely scattered locations
its part in the history of conditionally lethal
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along the A chromosome and belonged to 12
mutations. The paper of Epstein et a!. is
different complementation groups. I had lit- cited much more often because its impact
tle idea of the basis of their conditional
was far greater. By the time it was written,
lethality, but they were extremely useful
the mechanism of translational suppression
markers in my investigations of defective,
was somewhat understood, and it included a
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galactose-transducing variants of A.
much deeper analysis of the gene functions
When I returned to
2 the US in 1959, I en- associated with various T4 complementation
countered Bob Edgar (then at the California
groups that I had produced with A. Interest
Institute of Technology), who informed me
in similar studies on A was sparked
by a later
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that Dick Epstein had found mutants of
paper by Katherine Brooks, a graduate stuphage T4 (which they called “amber” mu- dent of mine, who investigated the effect of
tants) that had the same host range among
some A mutants on DNA replication as estiK-12 strains as my mutants. We agreed that
mated from genetic pool size. Most of the
this sounded as though C600 had an allelecitations to my paper are references to the
specific, gene-nonspecific suppressor. Edgar
origin of the mutants, which were widely dispointed out that such mutants might provide
tributed among A workers and remain in use.
a means for identifying all the genes essen- Some authors also cite the paper as the origtial for phage growth, and I recalled the
inal reference for specific A genes that they
earlier relevant work of Horowitz and
are studying.
Suppressible, thermosensitive, acid-sensitive, arid
alkali-sensitive mutants of coliphage A were isolated and used to identify and map most of the genes
determining functions necessary for plaque formation The suppressors allowing phage growth
were shown to include genuine suppressors of host
mutations [The SC!x indicate5 that this paper has
been cited in over 595 publications since 1961 1
Campbell A. Ordering of genetic sues in bacteriophage A by the use of galaciose-transducmg defective phages
Virology 9293-305, 1959 (Cued 40 times
2 Edgar R Conditional teihals (Cairns I, Steni C & Watson!, eds.) Phage and the origins 0/molecular biology
New York Cold Spring Harbor Laboratory. 1966 p 166-72
3 Horowhz N U & Leopold V. Some recent studies bearing on the one gene-one enzyme hypothesus
Cold Spring Harbor Symp 16 65-74, 1951 (Cued 60 times since 1955.)
4 Hendrta R, Roberts I. Stahl F & Welsberg It. Lambda Ii New York Cold Spring Harbor Laboratory, 1983. 694 p
5 Epuiein R H. aelle A, SteInberg C, Kellenberger E. aoy de Ia Tour E, Cheraucy It, Edgar It, Snuman M,
Denbardt C & LleIauals A. Physiological studies of conditional lethal mutations of bacteriophage T4D
Cold Spring Harbor Symp 28 375-94, 1963 (Cited 865 limes)
6 Brooki K. Studies in the physiological genetics of some suppressor-scusaitive mutants of bacteriophage A
Virology 26489-99, 1965 (Cited 105 iimes
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