APPENDIX C: CHRONOLOGY
F. Jacob and E. L. Wollman experimentally interrupt the mating process in E. coli and show that a piece of DNA is inserted from the donor bacterium into the recipient. P. Grabar and C. A. Williams devise the technique of immunoelectrophoresis to analyze complex mixtures of antigenic molecules. H. H. Flor puts forth the “gene-for-gene” hypothesis after studying the genetics of a parasite and its host simultaneously (the Melampsora-Linum system). J. H. Tjio and A. Levan demonstrate that the diploid chromosome number for humans is 46. C. O. Miller and four colleagues obtain from hydrolyzed DNA of herring sperm a substance that promotes cell division in tissue cultured plant cells. They determine the structure of the molecule and name it kinetin. B. C. Heezen and M. Ewing discover the Mid Oceanic Ridge, a formation of underwater mountains and rifts that girdles the globe. T. T. Puck, S. J. Cieciura, and P. I. Marcus succeed in growing clones of human cells in vitro. G. E. Palade and P. Siekevitz isolate ribosomes. A. Kornberg, I. R. Lehman, and S. E. Simms isolate and purify DNA polymer- ase 1 from E. coli. This is the first enzyme shown to take directions from a template molecule. M. J. Moses and D. Fawcett independently observe synaptonemal complexes in spermatocytes. W. L. Brown and E. O. Wilson define character displacement and give exam- ples of the phenomenon in insects, fish, amphibians, and birds. A. Gierer and G. Schramm and H. Fraenkel-Conrat demonstrate independently that a chemically pure nucleic acid, namely tobacco mosaic virus RNA, is infec- tious and genetically competent. E. Volkin and L. Astrachan infect E. coli with T2 bacteriophage and demon- strate the immediate synthesis of small amounts of a labile RNA. Its base com- position is similar to the genome of the virus, not the bacterium. They don’t realize it, but they have identified the first mRNA. S. A. Berson and R. S. Yalow report the first use of the radioimmunoassay procedure for the detection of insulin antibodies developed by patients in re- sponse to the administration of exogenous insulin. J. H. Taylor, P. S. Woods, and W. L. Hughes are the first to use tritiated thymi- dine for high-resolution autoradiography in experiments that demonstrate the semiconservative distribution of label during chromosome replication in Vicia faba. E. W. Sutherland and T. W. Rall isolate cyclic AMP and show that it is an adenine ribonucleotide. V. M. Ingram reports that normal and sickle-cell hemoglobin differ by a single amino acid substitution. This is the first proof that a gene mutation results in an abnormal amino acid sequence in a protein. A. Todd receives the Nobel Prize for his studies on the structure of nucleosides and nucleotides.
F. Jacob and E. L. Wollman demonstrate that the single linkage group of E. coli is circular and suggest that the different linkage groups found in different Hfr strains result from the insertion at different points of a factor in the circular linkage group that determines the rupture of the circle. F. H. C. Crick suggests that during protein formation the amino acid is carried to the template by an adaptor molecule containing nucleotides and that the adaptor is the part that actually fits on the RNA template. Crick thus predicts the discovery of transfer RNA. P. C. Zamecnik and his colleagues characterize amino acid-transfer RNA com- plexes. H. G. Callan and H. G. MacGregor demonstrate that the linear integrity of chromatids of amphibian lampbrush chromosomes is maintained by DNA, not protein. H. B. Kettlewell organizes surveys to determine the carbonaria frequencies in peppered moth populations throughout the United Kingdom. These show that the highest frequencies of melanic forms are located in industrial areas. M. Okamoto and, independently, R. Riley and V. Chapman discover genes that control the pairing of homoeologous chromosomes in wheat. F. C. Steward, M. O. Mapes, and K. Mears succeed in rearing sexually mature plants from single diploid cells derived from the secondary phloem of roots of the wild carrot, Daucus carota. They conclude that each cell of the multicellu- lar organism has all the ingredients necessary for the formation of the complete organism. M. Meselson and F. W. Stahl use the density gradient equilibrium centrifuga- tion technique to demonstrate the semiconservative distribution of density la- bel during DNA replication in E. coli. J. C. Kendrew and five colleagues produce a three-dimensional model of the myoglobin protein molecule obtained by x-ray analysis. They show that the molecule is composed almost entirely of alpha helices. Nobel Prizes are awarded to G. W. Beadle, E. L. Tatum, and J. Lederberg for their contributions to genetics and to F. Sanger for his contributions to protein chemistry. J. Lejeune, M. Gautier, and R. Turpin show that Down syndrome is a chromo- somal aberration involving trisomy of a small telocentric chromosome. C. E. Ford and four colleagues discover that females suffering from Turner syndrome are XO. P. A. Jacobs and J. A. Strong demonstrate that males suffering from Klinefelter syndrome are XXY. S. J. Singer conjugates ferritin with immunoglobulin to produce a labeled anti- body that is readily recognized under the electron microscope. R. L. Sinsheimer demonstrates that bacteriophage phiX174 of E. coli contains a single-stranded DNA molecule. E. G. Krebs, D. J. Graves, and E. H. Fischer isolate and purify the first protein kinase. F. M. Burnet improves Jerne’s selective theory of antibody formation by sug- gesting that the antigen stimulates the proliferation of only those cells that are genetically programmed to synthesize the complementary antibodies.
G. M. Edelman resolves immunoglobulin G into heavy and light chains. R. E. Franklin, D. L. D. Caspar, and A. Klug complete an x-ray crystallographic analysis that shows the architecture of the tobacco mosaic virus in three dimen- sions. A. Lima-de-Faria demonstrates by autoradiography that heterochromatin repli- cates later than euchromatin. `vremont-Comhaire, and E. Baeckeland demonstrate DNA in mitochondria using a combination of autoradiographic and Feulgen- staining techniques. K. McQuillen, R. B. Roberts, and R. J. Britten demonstrate in E. coli that ribo- somes are the sites where protein synthesis takes place. E. Freese proposes that mutation can occur as the result of single, base-pair changes in DNA. He coins the terms transitions and transversions. C. Pelling finds selective labeling of puffed regions of polytene chromosomes after they are incubated in a nutrient solution containing 3H uridine. R. H. Whittaker suggests the grouping of organisms into five kingdoms: the bacteria, the eukaryotic microorganisms, animals, plants, and fungi. S. Brenner and R. W. Horne develop the negative staining procedure for elec- tron microscopy of subcellular particles. S. Ochoa and A. Kornberg receive Nobel Prizes for their studies on the in vitro synthesis of nucleic acids. P. Nowell discovers phytohemagglutinin and demonstrates its use in stimulat- ing mitoses in human leukocyte cultures. A. Tsugita and five colleagues determine the complete sequence of the 158 amino acids in the coat protein subunit of the tobacco mosaic virus. P. Siekevitz and G. E. Palade describe the synthesis of secretory proteins on membrane-bound ribosomes. P. Doty and three colleagues demonstrate that complementary strands of DNA molecules can be separated and recombined. P. E. Polani and four colleagues document the first case of Down syndrome caused by a Robertsonian translocation. T. Watanabe and T. Fukusawa describe the mechanism of antibiotic resistance that results from the transfer of R plasmids during bacterial conjugation. G. Barski, S. Sorieul, and F. Cornefert report the first successful in vitro hybrid- ization of mammalian cells. U. Clever and P. Karlson experimentally induce specific puffing patterns in polytene chromosomes by injecting Chironomus larvae with ecdysone. H. H. Hess proposes the theory of sea floor spreading. M. F. Perutz and five colleagues determine the three-dimensional structure of hemoglobin at 5.5 A˚ resolution. P. B. Medawar and F. M. Burnet receive a Nobel Prize for their studies on immunological tolerance. F. Jacob and J. Monod publish “Genetic regulatory mechanisms in the synthesis of proteins,” a paper in which the theory of the operon is developed.
F. Jacob and J. Monod suggest that ribosomes do not contain the template responsible for the orderly assembly of amino acids. They propose that instead each DNA cistron causes synthesis of an RNA molecule of limited life span that harbors the amino acid sequence information in its nucleotide sequence. This molecule subsequently enters into temporary association with a ribosome and so confers upon it the ability to synthesize a given protein. Within months S. Brenner, F. Jacob, and M. Meselson identify a specific mRNA that is synthe- sized in E. coli after phage infection. M. F. Lyon and L. B. Russell independently provide evidence suggesting that in mammals one X chromosome is inactivated in some embryonic cells and their descendants, that the other is inactivated in the rest, and that mammalian females are consequently X-chromosome mosaics. S. Benzer discovers two sites in the rII region of the chromosome of phage T4 of E. coli that show exceptionally high rates of spontaneous mutation. He calls these hot spots. J. Josse, A. D. Kaiser, and A. Kornberg demonstrate that there is a difference in polarity between the complementary strands of the DNA helix, so that the sugars of one strand are oriented in a direction opposite to those in the other strand. This result confirms Crick’s antiparallel model of 1952. V. M. Ingram presents a theory explaining the evolution of the four known kinds of hemoglobin chains from a single primitive myoglobinlike heme protein by gene duplication and translocation. B. D. Hall and S. Spiegelman demonstrate that hybrid molecules can be formed containing one single-stranded DNA and one RNA molecule which are com- plementary in base sequence. Their technique opens the way to the isolation and characterization of messenger RNAs. S. B. Weiss and T. Nakamoto isolate an RNA polymerase from E. coli that uses DNA as a template. F. H. C. Crick, S. Brenner, and two colleagues show that the genetic language is made up of three-letter words. G. von Ehrenstein and F. Lipmann combine messenger RNA and ribosomes from rabbit reticulocytes with amino acid-transfer RNA complexes derived from E. coli. Since this cell-free system synthesized a protein similar to rabbit hemoglobin, they conclude that the genetic code is universal. W. Beermann demonstrates that a puffing locus on a Chironomus polytene chromosome is inherited in a Mendelian fashion. A. Wacker, H. Dellweg, and E. Lodemann show that thymine dimers are formed when DNA is irradiated with ultraviolet light. M. W. Nirenberg and J. H. Matthaei develop a cell-free system from E. coli that incorporates amino acids into protein when supplied with template RNA preparations. They show that the synthetic polynucleotide, polyuridylic acid, directs the synthesis of a protein resembling polyphenylalanine. M. Meselson and J. J. Weigle demonstrate in phage lambda that recombination involves breakage and reunion (but not replication) of the chromosome. H. Dintzis shows that the direction of synthesis of the hemoglobin molecule is from amino to carboxyl termini. H. Moor and three colleagues develop the first freeze-fracture procedure that permits ultrastructural observations, which are impossible with conventional sectioning methods.
U. Z. Littauer shows that ribosomes contain only two high-molecular-weight species of RNA, with sedimentation values of 16S and 23S in bacteria and 18S and about 28S in animals. I. Rubenstein, C. A. Thomas, and A. D. Hershey demonstrate that the DNA in the head of the T2 bacteriophage constitutes a single chromosome. C. B. Anfinsen and three colleagues show for ribonuclease A that the linear sequence of amino acids determines the unique three-dimensional structure of the protein. P. D. Mitchell proposes the theory of chemiosmosis to explain how ATP syn- thesis is accomplished. R. Guthrie develops a blood screening test for phenylketonuria. Screening of every newborn infant in Massachusetts for PKU will begin a year later. G. P. Georgiev and V. L. Mantieva discover and characterize heterogeneous nuclear RNA. L. Hayflick and P. S. Moorehead discover that the in vitro life span of human diploid cells in tissue culture is limited to about 50 doubling cycles. J. P. Waller and J. I. Harris find that bacterial ribosomes contain a large number of different proteins. H. Ris and W. Plaut show by electron microscopy that chloroplasts contain DNA. E. Zuckerkandl and L. Pauling calculate the approximate times of derivation of different hemoglobin chains from their common ancestors during eukaryotic evolution. F. M. Ritossa reports that the salivary gland chromosomes of Drosophila buskii respond to heat shocks by puffing. E. Beutler, M. Yeh, and V. E. Fairbanks study the erythrocytes of women het- erozygous for glucose-6-phosphate dehydrogenase deficiency. They find a mixed population of normal and G6PD-deficient cells and conclude that the adult human female is a mosaic of cells containing an inactivated X chromo- some, either maternal or paternal. S. Cohen isolates the epidermal growth factor from the salivary glands of mice. J. F. A. P. Miller, R. A. Good et al., and N. L. Warner et al. experimentally demonstrate the distinction between T and B lymphocytes. R. R. Porter uses enzymes to cleave immunoglobulin molecules. He demon- strates that each molecule has two antigen-binding portions (Fab) and a crystal- lizable segment (Fc) that does not bind antigen. He shows that the heavy and light chains are present in 1 : 1 ratio and suggests the four-chain model. D. A. Rodgers and G. E. McClearn discover differences between mouse strains in alcohol preference. J. V. Neel suggests that diabetes mellitus represents a “thrifty” genotype ren- dered detrimental by “progress.” U. Henning and C. Yanofsky show that amino acid replacements can arise from crossing over within triplets. J. B. Gurdon reports that a normal fertile frog can develop from an enucleated egg injected with a nucleus from an intestinal cell. This experiment demon- strates that somatic and germinal nuclei are qualitatively equivalent.
Polyribosomes are discovered independently in three laboratories Gierer, by J. R. Warner, A. Rich, and C. E. Hall, and by T. Staehelin and H. Noll). A. M. Campbell proposes that episomes become integrated into host chromo- somes by a crossover event resembling the exchanges that were previously re- ported between synapsed ring- and rod-shaped chromosomes in eukaryotes. W. Arber puts forward the restriction and modification model that predicts the presence of restriction endonucleases. Nobel Prizes in Physiology or Medicine are shared by J. D. Watson, F. H. C. Crick, and M. H. F. Wilkins for their studies on the three-dimensional structure of DNA. The Prize in Chemistry goes to M. F. Perutz and J. C. Kendrew for their x-ray crystallographic studies of hemoglobin and myoglobin. B. B. Levine, A. Ojida, and B. Benacerraf publish the first paper on the im- mune-response genes of guinea pigs. R. Rosset and R. Monier discover 5S rRNA and conclude that it is a constituent of the ribosome. They demonstrate subsequently that it is a component of the large ribosomal subunit. T. Okamoto and M. Takanami show that mRNA binds to the small ribosomal subunit. H. Noll, T. Staehelin, and F. O. Wettstein demonstrate the tape mechanism of protein synthesis. J. G. Gall produces evidence that the lampbrush chromatid contains a single DNA double helix. B. J. McCarthy and E. T. Bolton use their DNA-agar technique to measure genetic relatedness between diverse species of organisms. E. Hadorn demonstrates allotypic differentiation in cultured imaginal discs of Drosophila. F. Jacob and S. Brenner publish the replicon model. R. Sager and M. R. Ishida isolate chloroplast DNA from Chlamydomonas. K. R. Porter and M. A. Bonneville publish a collection of electron micrographs and associated legends that provides the first atlas of the ultrastructure of dif- ferent cell types. J. T. Wilson proposes the hot spot archipelago hypothesis to explain the origin of the Hawaiian islands. F. J. Vine and D. H. Matthews show that the rate of sea floor spreading can be calculated by dating parallel belts of rocks on the sea floor that show differ- ences in the directions of their magnetic fields. M. J. Schlesinger and C. Levinthal demonstrate that in vitro complementation results from the formation of a hybrid protein. The hybrid proteins studied were alkaline phosphatase molecules of E. coli. They were dimers that con- tained monomers with mutants at different sites. J. Cairns demonstrates by autoradiography that the genophore of Escherichia coli is circular and that during its semiconservative replication Y-shaped, repli- cating forks proceed in opposite directions from a starting point and generate two circular offspring genophores.
E. Margoliash determines the amino acid sequences for cytochrome c derived from a wide variety of species and generates the first phylogenetic tree for a specific gene product. L. B. Russell shows in the mouse that, when an X chromosome containing a translocated autosomal segment undergoes inactivation in somatic cells, the autosomal genes closest to the breakpoint are also inactivated. Thus the X inac- tivation spreads into the attached autosomal segment. E. Mayr publishes Animal Species and Evolution. This volume provides a synthe- sis of modern ideas concerning the mechanism of speciation, and it has a pro- found influence on scientists working in this area. I. R. Gibbons first isolates dynein from the arms on the microtubules of ciliary axonemes. R. B. Setlow and W. L. Carrier and, independently, R. P. Boyce and P. How- ard-Flanders describe the mechanism of excision repair in bacteria. A. S. Sarabhai and three colleagues establish the colinearity of gene and protein product in the case of the protein coating the head of virus T4 of E. coli. C. Yanofsky and four colleagues establish the colinearity of gene and protein product in the case of tryptophan synthetase for E. coli. M. Meselsen shows for lambda (λ) bacteriophage that genetic recombination occurs by breakage and rejoining of double stranded DNA molecules. M. S. Fox and M. K. Allen show that transformation in Streptococcus pneumon- iae involves incorporation of segments of single-stranded donor DNA into the DNA of the recipient. E. T. Mertz, L. S. Bates, and O. E. Nelson show that the opaque-2 mutation modifies the amino acid composition of the mature endosperm, resulting in a striking improvement in the nutritional quality of maize seed. J. G. Gorman, V. J. Freda, and W. Pollack demonstrate that the sensitization of Rh-negative mothers can be prevented by administration of Rh antibody immediately after delivery of their first Rh-positive baby. D. J. L. Luck and E. Reich isolate mitochondrial DNA from Neurospora. They demonstrate subsequently (1966) that this DNA replicates by the classical semiconservative mechanism. G. Marbaix and A. Burny isolate a 9S RNA from mouse reticulocytes and sug- gest that it may be mRNA. R. Holliday puts forth a model that defines a sequence of breakage and reunion events which must occur during crossing over between the DNA molecules of homologous chromosomes. J. W. Littlefield develops a method for selecting somatic cell hybrids utilizing HGPRT− and TK− fibroblasts cultured on HAT medium. D. D. Brown and J. B. Gurdon show that no synthesis of the 18S and 28S rRNAs occurs in Xenopus tadpoles homozygous for a deficiency covering the nucleolus organizer. W. D. Hamilton puts forth the genetical theory of social behavior. W. Gilbert finds that nascent proteins bind to the large ribosomal subunit, as do the tRNAs.
D. M. C. Hodgkin receives the Nobel Prize in chemistry for her pioneering studies in x-ray crystallography. It was in her laboratory at Oxford University that the three-dimensional structures of cholesterol, penicillin, cephalosporin, cobalamin, and insulin were elucidated. R. B. Merrifield and J. Stewart develop an automated method for synthesizing polypeptides on a solid supporting polymeric matrix. Some of the same auto- mation principles will later be adopted for automated nucleic acid synthesis by instruments called “gene machines.” D. D. Sabatini, Y. Tashiro, and G. E. Palade show that the large subunit of ribosome attaches to the ER membrane. R. W. Holley and his colleagues determine the complete sequence of alanine transfer RNA isolated from yeast. N. Hilschmann and L. Craig report that immunoglobulin molecules are made up of carboxyl-terminal segments that are constant in their amino acid compo- sition and amino-terminal segments that are variable. This finding poses the problem of how a gene can code for those portions of the protein that vary in their amino acid compositions. P. Karlson and four colleagues determine the complete structural configuration of ecdysone. D. H. Carr publishes cytological studies of spontaneous abortuses from a Cana- dian population. Over 20% show chromosomal abnormalities. S. Spiegelman and four colleagues succeed in the in vitro synthesis of a self- propagating infectious RNA (bacteriophage Q beta of E. coli) using a purified enzyme (Q beta replicase). S. Brenner, A. O. W. Stretton, and S. Kaplan deduce that UAG and UAA are the codons that signal the termination of a growing polypeptide. F. M. Ritossa and S. Spiegelman demonstrate that multiple transcription units producing the ribosomal RNAs of Drosophila reside in the nucleolus organizer regions of each X and Y chromosome. H. Harris and J. F. Watkins use the Sendai virus to fuse somatic cells derived from man and mouse and produce artificial interspecific heterokaryons. A. J. Clark identifies in E. coli the first gene (recA) whose product functions in genetic crossing over. F. Sanger, G. G. Brownlee, and B. G. Barrell describe a method for fingerprint- ing oligonucleotides from partially hydrolyzed RNA preparations. R. Rothman demonstrates that lambda phage has a specific attachment site on the E. coli chromosome. W. J. Dreyer and J. C. Bennett propose that antibody light chains are encoded by two distinct DNA sequences, one for the variable region and the other for the constant region. They suggest that there is only one constant region, but that the variable region contains hundreds of different minigenes. F. Jacob, J. Monod, and A. Lwoff receive a Nobel Prize for their contributions to microbial genetics. B. Weiss and C. C. Richardson isolate DNA ligase. M. M. K. Nass reports that mitochondrial DNA is a circular double-stranded molecule.
F. H. C. Crick puts forward the wobble hypothesis to explain the general pat- tern of degeneracy found in the genetic code. J. Adams and M. Cappecchi show that N-formylmethionyl-tRNA functions as the initiator of the polypeptide chain forming on a bacterial ribosome. W. Gilbert and B. Mu¨ller-Hill demonstrate that the lactose repressor of E. coli is a protein. M. Ptashne shows that the phage lambda repressor is a protein and that it binds directly to the lambda DNA molecule. F. M. Ritossa, K. C. Atwood, and S. Spiegelman show that the bobbed mutants of Drosophila are partial deficiencies of ribosomal DNA. H. Roller and three colleagues determine the structural formula for the juvenile hormone of Hyalophora cecropia. M. Waring and R. J. Britten demonstrate that vertebrate DNAs contain repeti- tious nucleotide sequences. R. S. Edgar and W. B. Wood analyze the genetically controlled steps in the assembly of the T4 bacteriophage. E. Terzaghi and five colleagues confirm that the genetic code is translated by the sequential reading of triplets of bases starting at a defined point in the mRNA for phage T4 lysozyme. V. A. McKusick publishes the one-volume Mendelian Inheritance in Man, a catalog that lists 1,487 genetic disorders in Homo sapiens. By the time of publi- cation of the three-volume 12th edition in 1998, the number of recognized hereditary diseases had risen to 8,600. H. Wallace and M. L. Birnstiel demonstrate that an anucleolate deletion in Xenopus laevis removes more than 99% of the rDNA. R. C. Lewontin and J. L. Hubby use electrophoretic methods to survey gene- controlled protein variants in natural populations of Drosophila pseudoobscura. They demonstrate that between 8 and 15% of all loci in the average individual genome are in the heterozygous condition. Using similar techniques, H. Harris demonstrates the existence of extensive enzyme polymorphisms in human pop- ulations. R. R. Ernst and W. A. Anderson show that the sensitivity of nuclear magnetic resonance spectroscopy can be greatly increased by replacing the slow radiofre- quency sweep of the specimen by short, intense RF pulses. P. Rous receives the Nobel Prize for his studies on oncogenic viruses. S. Spiegelman, D. R. Mills, and R. L. Peterson report the results of an in vitro evolution experiment that generates the smallest self-duplicating molecule known to science. H. G. Khorana and his co-workers use polynucleotides with known repeating di- and trinucleotide sequences to solve the genetic code. K. Taylor, Z. Hradecna, and W. Szybalski show that transcription in phage lambda can proceed in opposite directions in different genes on the same chro- mosome. Therefore, mRNA can originate from transcription units residing in the + and in the − strand of the same double helix. B. Mintz uses allophenic mice to demonstrate that melanocytes that provide color to the fur of the mouse are derived from 34 cells that have been deter- mined at an early stage in embryogenesis.