To How Many Cistrons Do These Mutations Belong

(a) To how many functional genes (cistrons) do these mutations belong?

(b) Which mutations belong to the same functional gene?

CHALLENGE QUESTIONS]_

31. As a summer project, a microbiology student independently isolates two mutations in E. coli that are auxotrophic for glycine (gly-). The student wants to know whether these two mutants occur at the same cistron. Outline a procedure that the student could use to determine whether these two gly-mutations occur within the same cistron.

32. A group of genetics students mix two auxotrophic strains of bacteria: one is leu+ trp+ his- met- and the other is leu-trp-his+ met+. After mixing the two strains, they plate the bacteria on minimal medium and observe a few prototrophic colonies (leu+ trp+ his+ met+). They assume that some gene transfer has taken place between the two strains. How can they determine whether the transfer of genes is due to conjugation, transduction, or transformation?

SUGGESTED READINGS]_

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Benzer, S. 1962. The fine structure of the gene. Scientific American 206(1):70- 84.

A good summary of Benzer's methodology for intragenic mapping, written by Benzer.

Birge, E. A. 2000. Bacterial and Bacteriophage Genetics, 4th ed. New York: Springer-Verlag.

An excellent textbook on the genetics of bacteria and bacteriophage.

Cole, L. A. 1996. The specter of biological weapons. Scientific American 275(6):60- 65.

Reviews germ warfare and what can be done to discourage it.

Dale, J. 1998. MolecularGenetics of Bacteria, 3rd ed. New York: Wiley. A concise summary of basic and molecular genetics of bacteria and bacteriophage.

Davies, J. 1994. Inactivation of antibiotics and the dissemination of resistance genes. Science 264:275 - 282. Reviews the crisis of antibiotic resistance in bacteria, with particular emphasis on the physiology and genetics of resistance.

Doolittle, R. F. 1998. Microbial genomes opened up. Nature 392:339 - 342.

Discussion of sequence data on bacterial genomes and what this information provides. Fraser, C. M., J. A. Eisen, and S. L. Salzberg. 2000. Microbial genome sequencing. Nature 406:799- 803. A short review of DNA sequencing of bacterial genomes.

Heidelberg, J. F., et al. 2000. DNA sequence of both chromosomes of the cholera pathogen Vibrio cholera. Nature 406:477 - 483.

Report of the sequencing and analysis of the genome of the bacterium that causes chorea. Hershey, A. D., and R. Rotman. 1942. Genetic recombination between host-range and plaque-type mutants of bacteriophage in single bacterial cells. Genetics 34:44 - 71. Original report of Hershey and Rotman's mapping experiments with phage.

Ippen-Ihler, K. A., and E. G. Minkley, Jr. 1986. The conjugation system of F, the fertility factor of Escherichia coli. Annual Review of Genetics 20:593 - 624. A detailed review of the F factor.

Kruse, H., and H. S0rum. 1994. Transfer of multiple drug resistance plasmids between bacteria of diverse origins in natural microenvironments. Applied and Environmental Microbiology 60:4015 - 4021.

Reports experiments demonstrating the transfer of R plasmids between diverse bacteria under natural conditions. Lederberg, J., and E. L. Tatum. 1946. Gene recombination in Escherichia coli. Nature 158:558.

One of the original descriptions of Lederberg and Tatum's discovery of gene transfer in bacteria. A slightly different set of experiments showing the same result were published in 1946 in Cold Spring Harbor Symposium on Quantitative Biology 11:113 -114.

Meselson, M., G. Guillemin, M. Hugh-Jones, A. Langmuir, I. Popova, A. Shelokov, and O. Yampolskaya. 1994. The

Sverdlovsk anthrax outbreak of 1979. Science 266:1202 - 1208. Report of the epidemiological studies concerning the anthrax outbreak in Sverdlovsk. Miller, R. V. 1998. Bacterial gene swapping in nature. Scientific American 278(1):66-71.

Discusses the importance of gene transfer by conjugation, transformation, and transduction in nature.

Novick, R. P. 1980. Plasmids. Scientific American 243(6):103 -124.

A good summary of plasmids and their importance in drug resistance.

Pace, N. R. 1997. A molecular view of microbial diversity and the biosphere. Science 276:734- 740. Good review of the diversity and classification of bacteria based on DNA sequence data. Scientific American. 1998. Volume 279, issue 1. This issue contains a special report with a number of articles on HIV and AIDS.

Walsh, C. 2000. Molecular mechanisms that confer antibacterial drug resistance. Nature 406:775 - 781.

A very good review of how antibiotic resistance develops and how antibiotics can be developed that are less likely to be resisted by bacteria.

Wollman, E. L., F. Jacob, and W. Hayes. 1962. Conjugation and genetic recombination in Echerichia coli K-12. Cold Spring Harbor Symposium on Quantitative Biology 21:141 - 162. Original work on the use of interrupted conjugation to map genes in E. coli.

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