Letter from Oliver E. Nelson, Jr. to Barbara McClintock
Nelson, a maize geneticist at the University of Wisconsin, worked primarily on biochemical genetics by the late 1960s and
early 1970s. In a series of studies during the previous decade he used Ac and Ds in his work on the waxy gene. In this letter,
which accompanied an ear of corn he sent to McClintock to study, Nelson discussed some of his recent work on maize and included
a paragraph on the "state of universities" in the politically tumultuous environment of the early 1970s.
Number of Image Pages:
2 (165,110 Bytes)
1970-05-13 (May 13, 1970)
Nelson, Oliver E. Jr
Original Repository: American Philosophical Society. Library. Barbara McClintock Papers
Reproduced with permission of Oliver Nelson.
Medical Subject Headings (MeSH):
Letter from Barbara McClintock to Oliver E. Nelson, Jr. (May 29, 1970)
Box Number: 1
Folder Number: 7
May 13, 1970
Thanks for your letters with the selected seeds to illustrate simultaneous loss of a1m-3 and Sh2. The large package of seeds
also arrived today, and I'll be looking for the second package. I'll be delighted to have the other mutables. I'll
be propagating these against possible future use.
Since talking with you, our Florida crop has been returned and inspected. It is now clear that the plant from which I sent
you samples last fall was indeed heterozygous for a mutable sh2 that responds to Ac. That plant was 43117J and was (as it
turned out) [scientific formula] This plant was crossed onto W22 A1 A2 CR pr in 1969 and a number of selves made in Florida
in 1970. The plants carrying the a1m-3 chromosome were of three types: (1) those where both a1m-3 --> A1 and sh2m-1 -->
Sh2 events are observable; (2) a few in which sh2m --> Sh2 events are seen but a1m-3 --> A1 events had already taken
place so the kernels are quite uniformly dark; (3) plants segregating for a1m-3 and sh2m-1, but AC is absent. Seeds illustrating
all these classes are being sent under separate cover for your inspection, and I'll be interested to learn if you confirm
I've only sent the kernels in which the Sh2 sectors are rather large. There are others (similar to the "puffy"
type I sent last fall) which I suspect to arise from numerous late events. But the edges are not sharp on the Sh2 sectors
(possibly because ADPG may diffuse from cell to cell), and it is difficult to be certain that one is actually seeing small
It's also interesting that the sh2m-1 is linked to a1m-3. Transposition of Ds to Sh2 on this chromosome must have been
from the homologous chromatid.
I'm also sending some kernels from last fall's progeny showing Sh2, sectors arising in the endosperm. Some of these
are not simultaneous losses of al m-1 and Sh2. Some could be, and with some colorless k's, it isn't possible to say.
All these arise from a sh2s/sh2s; wx/wx stock pollinated by your stocks [scientific formula] with various numbers of Spm present.
Also being sent is an ear of the type I described in one of our conversations. This is from your stock 8777(2) I x 8786A(2)
[scientific formula] pollinated by sh2s/sh2s; wx/wx; Y/Y. The intriguing feature is the numerous white kernels which seem
to be dominant whole kernel events. I do see several kernels with white and yellow sectors, but this is rare. At any rate,
I've seen nothing like this before and wonder if it's familiar to you.
You may well be gloomy about the state of the universities. I am. I started this letter while taking an evening fire watch
here in the Genetics Building. We had decided to have a graduate student or staff member here around the clock in the event
a radical student decided to toss in a Molotov cocktail. So far this hasn't happened, but it might still. Between the
radical students who are wrapping in lots of demands along with the dissatisfaction with the war and a conservative board
of regents, the university might well be ground up. Certainly, it will never again be the same. Many buildings here are ringed
by the National Guard. We're having a week-long moratorium on classes with marathon discussions of issues. It's not
an atmosphere conducive to academic life, and I find it terribly difficult to concentrate on anything. Imagine how difficult
it is for students who are not as motivated as I and who don't escape to a calm and restful home every evening.
Thanks again for all the care you've taken to send seed. With best personal regards, I am