Dr. George B. Johnson
ll June l942 in Newport News, Virginia
6969 Amherst Ave.
University City, MO 63130
(314) 809-0690 (M)
Department of Biology
Washington University, Box 1137
St. Louis, Missouri 63130-4899
B.A., Dartmouth College, l964. English
M.A., Dartmouth College, l966. Biology
Ph.D., Stanford University, l972. Population Biology
Assistant Professor of Biology, Washington University, St. Louis,
MO, l972- l976
Research Fellow, Carnegie Institute of Washington, Department of
Plant Biology, Stanford, California, l975- l976
Associate Professor of Biology, Washington University, St. Louis,
Associate Professor of Genetics, Washington University School of
Medicine, St. Louis, MO, 1976-1981
Lector, Genetisk Institut, Aarhus Universitet, Aarhus, Denmark,
April- August, 1977
Professor of Biology, Washington University, St. Louis, MO,
Professor of Genetics, Washington University School of Medicine,
St. Louis, MO, 1981- 2004
Director, The Living World education center, St. Louis Zoo, 1987-
Professor Emeritus of Biology, Washington University, St. Louis,
MO, 2004- Present.
Honors and Offices Held
Carnegie Institution of Washington Fellow, 1975-1976
Associate Editor, EVOLUTION, 1976-1982
Director, Graduate Program in Population Biology & Ecology,
Washington University, 1977-1982
John Simon Guggenheim Foundation Fellow, 1982-1983
Leader, National Geographic expedition to New Zealand, 1985
U.S. Committee Member, International Union of Biological
Governing Board, Missouri Nature Conservancy, 1989-1992
Member, National Research Council Commission on Teacher
Board, EarthWays, 1992-1994
Board, Missouri Audubon Society, 1993-94
Editorial Fellow, St. Louis Post Dispatch, 1999
Science Advisory Board, St. Louis Science Center, 1999-
Board, Academy of Science of St. Louis, 2000-
I served for 31 years on the Biology Faculty of Washington University, a teaching professor of three large undergraduate courses: Genetics, Introduction to Biology (a general "issues" course for non- majors) and Biology of Dinosaurs (a non-majors course on dinosaurs). I retired from academic teaching in 2004.
During the period 1972-1982 I pursued an active research career, focusing on genetic variation at enzyme loci, the degree to which this may reflect evolutionary responses to particular environmental selective pressures, and ways in which such variation may be used to assess evolutionary history. This work was supported by $476,100 in Federal grant support, and resulted in 43 publications in scientific journals.
From 1983 to present I have substituted writing for research, authoring nine different biology texts. Four of these have been in collaboration with Peter Raven, Director of the Missouri Botanical Garden. My four university biology texts and two high school biology texts have proven highly successful, and have been used by over 3 million students.
From 1987 to 1990 I served as Director of The Living World education center at the St. Louis Zoo. In this capacity I was responsible for development of a broad range of innovative exhibits and an array of new educational programs. The Living World opened to the public in June of 1989 and attracted over 1 million visitors in its initial year.
I have served on a National Research Council task force to improve high school biology teaching, and have become increasingly involved in efforts to incorporate interactive learning into our nation's classrooms.
I have also become increasingly involved in public science education. From 1999 to 2009 I wrote a weekly science column called ON SCIENCE, initially in the St. Louis Post Dispatch newspaper and later in a web-based newspaper, the St. Louis Beacon. (These columns can be read on the internet at http://txtwriter.com).
In the years 1972-1982, my research focused on three related problems, each arising from study of genetic variation in natural populations.
1) The first problem I addressed concerned the functional consequences of naturally occurring genetic variation at enzyme loci. To assess the degree to which enzyme polymorphism might be adaptive, I carried out a detailed analysis of a simple enzyme system, a- glycerophosphate dehydrogenase, in alpine butterflies of the genus Colias. Working with well-characterized Colorado population of Colias, I found genetic variation at this locus to be associated with habitat: heterozygosity was high only in populations living in montane environments; alpine and lowland populations were much less variable. The role of habitat was confirmed in subsequent studies in which I examined a series of populations, each of which encompassed both alpine and montane habitats. Butterfly movement within populations proved to be significant, but the populations were not homogeneous despite the intermixing. Each exhibited a cline in allele frequency within the population from alpine down to montane. Selection appeared to be acting against one of the alleles in alpine habitats.
I have since examined 15 other enzyme loci in these same populations, and I find evidence of highly organized metabolic phenotypes. Most of the coordination in variation seems to involve enzymes of potential regulatory importance.
2) In purifying and characterizing variant forms of aGPDH, it became clear that the two electrophoretic alleles were heterogeneous. I thus tried increasing the resolution of the electrophoretic surveys, accomplishing this by varying the pore geometry of gels in a controlled way. By employing a series of gels, each of progressively smaller pore size, the response of proteins to molecular sieving may be compared. It is possible to achieve great resolving power in this fashion, discriminating between variants that differ only subtly in shape. Reanalyzing the alpine- montane butterfly populations, not two alleles were found, but five! In general, in butterflies, Drosophila, or mice, the higher resolution technique has revealed two to three times the amount of enzyme polymorphism previously reported.
I have increased the resolution of the technique another notch by employing controlled perturbations of the proteins being compared. I find that variants of similar shape often have different propensities to change shape in response to mild denaturants (CaCl, slight temperature increases, D O). Using these perturbation probes, I am currently attempting to develop a two-dimensional gel (mild perturbation + gradient in one direction, isoelectric focusing in the other) of a very high resolution.
3) The levels of heritable variation detected by high-resolution electrophoretic techniques are unexpectedly high, so I set out to test the underlying genetic assumption that the genetic variants of an enzyme are alleles of the same locus. The approach was to construct a family of Drosophila lines, each with a different, randomly chosen chromosome 2 deriving from nature, and all with the same chromosome 3--and then to examine an enzyme (xanthine dehydrogenase) mapping to chromosome 3 for genetic variation. As all lines have identical XDH genes, no genetic variation in XDH enzyme should be observed unless produced by other genes on chromosome 2. Considerable variation is detected. Apparently the high resolution gels are detecting not only allelic variation but also subtle transcriptional modifications.
It seems clear from the results of these years that analyzing enzyme variation in nature may not be the straightforward problem it first appeared. Progress will require detailed genetic analysis. Few organisms offer the genetic power of meiotic analysis in Drosophila, however. The alpine butterflies, for example, have 62 chromosomes, and can be raised in the lab only with difficulty. With this in mind, my later work focused on analysis of genetic variation at the DNA level.
My initial efforts centered on the ribosomal protein genes from Ranunculus. I used cross hybridization to the maize genes and Southern analysis to isolate the restriction fragment containing the genes from the buttercup, prepared detailed restriction maps, and began preparing a genomic library. It is my ultimate goal, should I return to this work, to compare sequences among a series of alpine Ranunculus species which have diverged from one another at different times, in order to examine the influence of time and of ecological factors upon the rate of genetic divergence.
In parallel, I have compared rDNA sequences in the seven tribes of the Plant family Onagraceae, in an attempt to address various taxonomic issues relating to the phylogenetic history of the family.
1. Wild type and mutant stocks of Aspergillus nidulans, (with R.W. Barratt and W.N. Ogata), 1965, Genetics 52: 233-234
2. Purification and characterization of glutamic acid dehydrogenase from Escherichia coli strain K-12. Master's thesis, Dartmouth College, 1966
3. Analysis of enzyme variation in natural populations of the butterfly Colias eurytheme, 1971, Proc. Natl. Acad. Sci. USA 68: 997-1001
4. The relationship of enzyme polymorphism to metabolic function, 1971, Nature 232: 347-348
5. The selective significance of biochemical polymorphism in Colias butterflies, Doctoral dissertation, Stanford University, 1972
6. Enzyme polymorphisms: Evidence that they are not selectively neutral, 1972, Nature New Biol. 237: 170-171
7. The relationship of enzyme polymorphism to species diversity, 1973, Nature 242: 193-194
8. Enzyme polymorphism and biosystematics: The hypothesis of selective neutrality, 1973, Annual Reviews of Ecology and Systematics, 4: 93-116
9. The importance of substrate variability to enzyme polymorphism, 1973, Nature New Biol. 243: 1 51-153
10. On the hypothesis that polymorphic enzyme alleles are selectively neutral. I. The evenness of allele frequency distribution, (with M.W. Feldman), 1973, Theor. Pop. Biol. 4: 209-221
11. Enzyme polymorphism and metabolism, 1974, Science 184: 28-37
12. On the estimation of effective number of alleles from electrophoretic data, 1974, Genetics 78: 771-776
13. Studying genetic variation in human populations, 1974, Jour. Heredity 65: 260-261
14. The use of internal standards in electrophoretic surveys of enzyme polymorphism, 1975, Biochemical Genetics 13: 833-847
15. Enzyme polymorphism and adaptation, 1975, Stadler Genetics Symposium 7: 91-116
16. Mechanisms of evolution and speciation, 1975, In LIFE: THE INDIVIDUAL AND THE SPECIES (T. Lane, Ed.). Mosby Publishing Company, St. Louis, Missouri.
17. Polymorphism and predictability at the alpha-glycerophosphate dehydrogenase locus in Colias butterflies: Gradients in allele frequencies within a single population, 1976, Biochemical Genetics 14: 403-426
18. Genetic polymorphism and enzyme function, 1976, In THE MOLECULAR STUDY OF BIOLOGICAL EVOLUTION, Chapter 3, pp. 46-59 (F. Ayala, Ed.), Sinauer Associates, Inc., Sunderland, Massachusetts.
19. Hidden alleles at the alpha-glycerophosphate dehydrogenase locus in Colias butterflies, 1976, Genetics 83: 149-167
20. Enzyme polymorphism and adaptation in alpine butterflies, 1976, In EVOLUTION WITHIN POPULATIONS, Ann. Mo. Bot. Garden 63: 248-261
21. Enzyme polymorphism in the butterfly Colias: Selection on metabolic phenotypes, 1976, Carnegie Institution of Washington Yearbook 75: 440- 449
22. Characterization of electrophoretically hidden variation in the butterfly Colias, 1976, Carnegie Institution of Washington Yearbook 75: 449-456
23. Factors altering the gel sieving behavior of proteins: The effect of deuterium oxide, 1976, Carnegie Institution of Washington Yearbook 75: 456-459
24. Evaluation of the stepwise mutation model of electrophoretic mobility: Comparison of the gel sieving behavior of alleles at the esterase-5 locus of Drosophila pseudoobscura, 1977, Genetics 87: 139-157. Abstract: Genetics 83: s36 (1976)
25. Characterization of electrophoretically cryptic variation in the alpine butterfly Colias meadii, 1977, Biochemical Genetics 15: 665-693
26. Hidden heterogeneity among electrophoretic alleles, 1977, In MEASURING SELECTION IN NATURAL POPULATIONS (F. Christiansen, T. Fenchel, Eds.), Springer-Verlag, Berlin: 223-244
27. Assessing electrophoretic similarity: The problem of hidden heterogeneity, 1977, Annual Reviews of Ecology and Systematics, Vol. 8: 309-328
28. Isozymes, allozymes, and enzyme polymorphism: Structural constraints on polymorphic variation, 1978, Isozymes: Current Topics in Biological and Medical Research, Vol. 2: 1-21
29. Enzyme polymorphism: Metabolic considerations, l978, Metabolic Therapy, 7: l-4
30. Structural flexibility of isozyme variants: Genetic variants in Drosophila disguised by cofactor and subunit binding, l978, Proc. Nat. Acad. Sci. USA 75: 395-399. Abstract: Genetics 86: s33, (l977)
3l. Genetically controlled variation in conformation of enzymes, l979, Prog. Nucleic Acid Res. Molec. Biol. 22: 293-326
32. Genetic variation in the physiological phenotype, l979, In POPULATION BIOLOGY OF PLANTS (O. Solbrig, S. Jain, G. Johnson & P. Raven, Eds.), Columbia Univ. Press, N.Y.: p. 62-83
33. Genetic polymorphism at enzyme loci, l979, In PHYSIOLOGICAL GENETICS (J. Scandalios, Ed.), Academic Press, N.Y.: 239-273
34. Post-translational modification as a potential explanation of high levels of enzyme polymorphism (with V. Finnerty), l979, Genetics 9l: 695-722
35. Gene expression in Drosophila: Characterization of the enzymes produced by certain complementary maroon-like heterozygotes (with V. Finnerty, and M. McCarron), l979, Molec. Gen. Genet., 172: 37-43
36. The genetics of electrophoretic variation: a response (with V. Finnerty), 1979, Genetics 92: 357-360
37. Increasing the resolution of polyacrylamide gel electrophoresis by varying the degree of gel cross-linking, 1979, Biochemical Genetics 7: 499-5l6
38. Unvermutete Genetische Variation an Enzymorten (with V. Loeschcke), l979, Biologisches Zentralblatt, 98: l63-l73
39. Structural vs. post-translational components of genic variation (with V. Finnerty), 1979, Genetics 92: 683-684
40. POPULATION BIOLOGY OF PLANTS, l980, Editor (with O. Solbrig, S. Jain & P. Raven), Columbia Univ. Press, N.Y.
4l. Polyploidy, plants, and electrophoresis (with B. Carr), l980. In POLYPLOIDY (W. Lewis, Ed.), Academic Press, N.Y.
42. Post-translational modification of xanthine dehydrogenase in natural populations of Drosophila melanogaster (with D. Hartl and V. Finnerty). 1981. Genetics 98: 817-831
43. Gel sieving electrophoresis: A description of procedures and analysis. In METHODS OF BIOCHEMICAL ANALYSIS (D. Glick, Ed.), 1983, Interscience Publishers, New York.
44. Phylogenetic Implications of Ribosomal DNA Restriction Site Variation in the Plant Family Onagraceae (with J. Crisci, E. Zimmer, P. Hoch, C. Mudd and N. Pan), 1990, Ann. Mo. Bot. Gard 77: 523-538
1. BIOLOGY (with P. Raven and later editions with Jonathan Losos, Kennith Mason, and Susan Singer), 1986, 1989, 1992, 1996, 1999, 2002, 2005, 2008, 2011, 2014. McGraw-Hill Publishing Company, Dubuque, Iowa.
2. UNDERSTANDING BIOLOGY (with P. Raven), 1988, 1991, 1995. Wm. C. Brown Publishing Company, Dubuque, Iowa.
3. ENVIRONMENT (with P. Raven and L. Berg) 1993, 1996. Saunders Publishing Company, Philadelphia, Pennsylvania.
4. BIOLOGY VISUALIZING LIFE. 1993, 1997. Holt Rinehart Winston, Austin, Texas.
5. HUMAN BIOLOGY: CONCEPTS AND ISSUES, 1994. W.C. Brown Publishing Co., Dubuque, Iowa.
6. BIOLOGY: PRINCIPLES AND EXPLORATIONS, 1995, 2000 (with P. Raven). Holt Rinehart Winston, Austin, Texas.
7. HOW SCIENTISTS THINK: KEY EXPERIMENTS IN GENETICS, 1995. W.C. Brown Publishing Company, Dubuque, Iowa.
8. THE LIVING WORLD, 1996, 2000, 2003, 2006, 2008, 2010, 2012, 2014. McGraw-Hill Publishing Company, Dubuque, Iowa.
9. ESSENTIALS OF THE LIVING WORLD, 2006, 2008, 2010, 2013. McGraw-Hill Publishing Company, Dubuque, Iowa.
Interactive CD-ROM Software
1. EXPLORING HUMAN BIOLOGY, 1995. W.C. Brown Publishing Company, Dubuque, Iowa.
2. EXPLORING CELL BIOLOGY AND GENETICS, 1996. W.C. Brown Publishing Company, Dubuque, Iowa.