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The Joshua Lederberg Papers

Reverse-Mutation and Adaptation in Leucineless Neurospora Annotation pdf (972,525 Bytes) ocr (29,097 Bytes)
Reverse-Mutation and Adaptation in Leucineless Neurospora
Lederberg's work under the tutelage of his mentor, Francis J. Ryan at Columbia University.
Number of Image Pages:
11 (972,525 Bytes)
1946-06 (June 1946)
Ryan, Francis J.
Lederberg, Joshua
Periodical: Ryan, Francis J., and Joshua Lederberg. "Reverse-Mutation and Adaptation in Leucineless Neurospora." Proceedings of the National Academy of Sciences of the United States of America 32, 6 (June 1946): 163-173. Article. 11 Images.
Lederberg UI: P1
National Academy of Sciences (U.S.)
This item is in the public domain. It may be used without permission.
Medical Subject Headings (MeSH):
Exhibit Category:
The Development of Bacterial Genetics
Lederberg Grouping: Published Scientific Article
Metadata Record Letter from Joshua Lederberg to David Perkins (March 3, 1983) pdf (41,362 Bytes)
Metadata Record Letter from David Perkins to Joshua Lederberg (March 8, 1983) pdf (44,682 Bytes) ocr (789 Bytes)
Box Number: 79
Folder Number: 1
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Series: Writings
SubSeries: Published Scientific Articles
Folder: P1: "Reverse-Mutation and Adaptation in Leucineless Neurospora" (1946)
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Annotation by Joshua Lederberg:
KW: heterokaryons; reverse mutation leucineless Neurospora;

My work under Ryan's tutelage.  He had originally observed "adaptation""
in growth tubes with leu- Neurospora.  I must have had many arguments
with him about possible mechanisms, including the most obvious: reverse
mutation.  This had not previously been documented with auxotrophs!
And barring selective procedures, it was barely known at all in
Drosophila etc.  Today of course it is a ubiquitous nuisance!

The main finding was that backcrosses of revertants to wild type
gave no auxotrophic progeny.  This of course might be defeated by a
moderately closely linked suppressor.

More perplexing was the population dynamics of the leu+/leu- heterokaryon:
Paradoxically, leu- nuclei would prevail given any selective
platform at all.  This is not understood at all.  Something analgous
may occur with pantothenate +/-  cf. Rowland H. Davis @ UC/I.
 Am J Botany  47:648-654 1960; it may be tied in with broader issues of
heterokaryon incompatibility, though these are usually connected with
the mating type locoi.

This is discussed further by Ryan (1946) - Cold Spr Harb Symp

Not every leu+ strain is inhibited by leu-., and by TH Pittenger
& TG Brawner  Genetics 46:1645-1663  1961

Ryan was concerned that the effects of leucine might be seen as
somehow lamarckian.

jl 7/25/98

Elementary question : is this selection at level of nuclei or of
competing multinucleate hyphal tips?

jl 7/16/98