Stadler Genetics Symposia, volume 11, 1979 (MU)
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Contents of volume 11
- Acknowledgments
- Contents
- Participants
- E. R. Sears Scholarship Fund
- Gary E. Hart: GENETICAL AND CHROMOSOMAL RELATIONSHIPS AMONG THE WHEATS AND THEIR RELATIVES
- Gisela Mosig, Richard Dannenberg, Debabrota Ghosal, Andreas Luder, Stephen Benedict and Susan Bock: GENERAL GENETIC RECOMBINATION IN BACTERIOPHAGE T4
- Achilles Dugaiczyk, Savio L. C. Woo and Bert W. O'Malley: MOLECULAR STRUCTURE OF THE OVALBUMIN GENE AND ITS GENOTYPIC ALLELES
- Donald J. Merlo: TI PLASMIDS OF AGROBACTERIUM: POTENTIALS FOR GENETIC ENGINEERING
- Rudolph Hagemann: GENETICS AND MOLECULAR BIOLOGY OF PLASTIDS OF HIGHER PLANTS
- James A. Gavan: FOSSILS, APES, MAN, AND CULTURE
- Winona C. Barker and Margaret O. Dayhoff: ROLE OF GENE DUPLICATION IN THE EVOLUTION OF COMPLEX PHYSIOLOGICAL MECHANISMS: AN ASSESSMENT BASED ON PROTEIN SEQUENCE DATA
- David D. Perkins: NEUROSPORA AS AN OBJECT FOR CYTOGENETIC RESEARCH
- Kevin McEntee and George M. Weinstock: THE RecA PROTEIN OF E. coli: REGULATION AND FUNCTION IN RECOMBINATION AND REPAIR
- Cumulative Contents of the Proceedings of the Stadler Genetics Symposia
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Item Stadler Genetics Symposia, volume 11, 1979 : Preliminaries and back matter(University of Missouri, Agricultural Experiment Station, 1979) Stadler Genetics Symposium (11th : 1979 : Columbia, Missouri)Item Neurospora as an object for cytogenetic research : chromosome rearrangements, crossing over, duplications, meiosis, meiotic drive, recombination(University of Missouri, Agricultural Experiment Station, 1979) Perkins, David D.; Stadler Genetics Symposium (11th : 1979 : Columbia, Missouri)Several lines of research have been stimulated because the direct results of Mendelian segregation are apparent in Neurospora asci. Spore killer genes provide an example. When across is heterozygous for Spore killer, four ascospores in each ascus are white and inviable. Surviving ascospores contain the killer allele, which thus shows meiotic drive. Meiotic and postmeiotic divisions are completed before killing occurs.---Chromosome rearrangements are frequent; many have been characterized. Rearrangements are detected initially because they produce white deficiency ascospores. Provisional diagnosis is by visual inspection of asci: the frequencies and patterns of white ascospores are characteristically different for different rearrangement types. When insertional or terminal translocations are crossed by normal sequence, meiotic recombination results in progeny that contain a nontandem duplication. The duplications can provide information on map sequence, dominance, nuclear autonomy, vegetative incompatibility, nucleolus-organizer behavior, mitotic recombination, chromosome stability, and chromosome organization.---Some mutants that impair meiosis produce no ascospores; others produce hypoploid ascospores that are inviable.---Light microscopy has been effective in detailing pachytene chromosome morphology, identifying rearranged chromosomes, and describing the behavior of chromosomes and organelles during meiosis and ascus development in normal and mutant genotypes. Studies of the synaptonemal complex are favored by the small genome size of Neurospora.---Crossing over in Neurospora resembles that in higher organisms, with positive chiasma interference. When gene conversion occurs, flanking markers are recombined with a probability less than 50 percent, suggesting a constraint on random isomerization in molecular recombination models. Recombination frequencies in specific local regions are precisely controlled by a system of regulatory genes.---Natural populations of Neurospora are readily sampled. Chromosomal polymorphisms have not been detected, although genic polymorphisms are abundant. Karyotypes are similar in all known species.---Beginnings have been made using Neurospora in molecular cytogenetics and for research with recombinant DNA.Item General genetic recombination in bacteriophage T4 : DNA exchange, DNA- protein-protein interactions(University of Missouri, Agricultural Experiment Station, 1979) Mosig, Gisela; Dannenberg, Richard; Ghosal, Debabrota; Luder, Andreas; Benedict, Stephen; Bock, Susan; Stadler Genetics Symposium (11th : 1979 : Columbia, Missouri)We will discuss current models of genetic recombination emphasizing their general aspects and the specific points which have been demonstrated in phage T4. Recombination in this phage occurs preferentially (although not exclusively) near chromosomal ends. It depends on single-stranded regions (which are formed either by partial degradation or by partial synthesis). DNA replication stimulates recombination in T4 mainly because it generates single-stranded termini in partially replicated chromosomes. Such single-stranded termini invade homologous regions of duplex molecules, thereby generating recombinational forks. These forks can be resolved to yield insertion-type or crossover-type recombinants. Alternatively, they can be reconverted to replication forks. Thus, no clear-cut distinction between replicative or recombinational forks can be made. Because the T4 chromosomes are circularly permuted, growing points reach ends and recombinational forks accumulate soon after the onset of DNA replication. The invading single-strands generate a network of DNA whose complexity increases with increasing numbers of infecting particles and with time after infection. The conversion of these forks to replication forks rapidly accelerates overall DNA synthesis in viral infected cells. The networks are finally resolved during maturation. The interconversion of recombinational and replication forks is facilitated by the multiple roles of several proteins in replication and recombination. Activities of these proteins in both processes are modulated by specific interactions with the T4 gene-32 protein. This protein, which presumably coats all intracellular single-stranded DNA regions provides an ordering principle for the coordinated action, in time and space, of the other proteins acting on DNA. Additional stabilization of these interactions occurs by the interaction of these proteins with membrane components.Item Ti plasmids of agrobacterium : potentials for genetic engineering : plasmids, genetic engineering, crown gall, tumors(University of Missouri, Agricultural Experiment Station, 1979) Merlo, Donald J.; Stadler Genetics Symposium (11th : 1979 : Columbia, Missouri)Crown gall disease of dicotylendenous plants, induced by Agrobacterium tumefaciens, provides a unique system for the study of pathogen-host interplay at the molecular level. By means of large Ti plasmids borne by virulent strains of the bacterium, the pathogen redirects normal plant cell metabolism to provide a physiological regime that is beneficial to the pathogen, and also results in tumor formation on the plant. This redirection of plant metabolism is accomplished through the incorporation, maintenance, and expression of part of the Ti plasmid in the plant cell; thus crown gall serves as the first naturally-occurring example of genetic engineering of a eukaryotic cell by a prokaryote. Through the use of in vivo or in vitro techniques, it may be possible to exploit the crown gall system for use in insertion of man-selected genes into higher plants, thereby providing plants with genetic makeup not easily available through conventional genetic techniques.Item The recA protein of E. coli : regulation and function in recombination and repair : UV induction, autoregulatory model, DNA binding protein, DNA renaturation, strand assimilation(University of Missouri, Agricultural Experiment Station, 1979) McEntee, Kevin; Weinstock, George M.; Stadler Genetics Symposium (11th : 1979 : Columbia, Missouri)In Escherichia coli, the recA function is required for general recombination, repair of DNA damage and a diverse group of functions which are coordinately expressed following DNA damage or arrest of DNA synthesis (SOS functions ). These latter functions include UV mutagenesis, W- reactivation of damaged phage DNA, prophage induction and cell filamentation. In this paper we summarize experiments which have elucidated regulatory and functional aspects of the recA gene product. Biochemical and genetic data suggest a model for control of recA gene expression in which the recA protein auto regulates its own synthesis following UV irradiation or other forms of DNA damage. The features of this autoregulatory mechanism are different from those proposed for gene 32 protein of phage T4. Biochemical experiments with homogeneous wild type and mutant forms of RecA protein reveal that this unique DNA binding protein catalyzes DNA renaturation and single strand assimilation reactions which are coupled to ATP hydrolysis. These results indicate that RecA protein catalyzes strand transfer during the initiation of genetic recombination and during post-replication repair of damaged DNA in vivo.