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The emergence of bacterial genetics
~]OOK family as 'alternate (sic) designations' for the particular hsp. Grp78 is not an 'alternate designation' for hsp70, it is a different protein. Fortunately the hsp-related families are also reviewed in chapter 10, which provides an excellent comprehensive survey of
The Emergence of Bacterial Genetics by ThomasBrock,ColdSpringHarbor LaboratoryPress, 1990.$55.00(xix+ 346 pages) ISBN0 87969350 9 This worthwhile book is a history of discovery in bacterial genetics up to the early 1960s. If I needed persuasion that such a book was necessary or timely, it was provided recently by an excellent postdoctoral bacterial geneticist who assumed that the Salmonella his genes must have been ordered by DNA sequencing: mapping by classical transduction is evidently almost lost in the mists of time! Brock recounts how well genetics got on without bacteria for the first four decades of the 20th century, before the subject reached a point of near-stagnation because of the virtual impossibility of doing biochemical studies on genes and gene action in higher organisms. Meanwhile, bacteriologists (struggling along without genetics) were discovering phages (in Shigella and micrococci) and lysogeny (in Bacillus megaterium), transformation (in Pneumococcus), and enzyme induction in yeast (an honorary bacterium), Enterobacter aerogenes and Bacillus subtilis. These discoveries acquired major significance only after Luria, Delbruck and Tatum showed that E. coli had genes that could be mutated, and when E. coli, in the hands of Joshua Lederberg, became a truly sexy subject for research. From then on bacterial genetics became - for many people (Broc~k included) - almost synonymous with the genetics of E. coli and its
H~EVIEWS
the subject, although unfortunately it does not extend its coverage to the genes encoding the hsps. Setting aside its potential for confusion, Stress Proteins in Biology a n d Medicine provides a thorough survey of the hsps and should greatly benefit the careful
reader interested in learning more about heat shock and its implications for biology.
phages. By the end of the period covered in this book, this had led to the first proper understanding of gene expression and its regulation, and the cracking of the genetic code; and some of the foundation stones of the recombinant DNA revolution were in place. Because it cannot date (unless history becomes obsolete) this book could presumably be bought and read for the indefinite future. Is it good enough? More or less, I think. The main topics are there, though one may cavil about omissions such as Fleming's discovery of penicillin (antibiotics were crucial to some of the key experiments that Brock describes), or the famous paper in which Crick et al. constructed T4 recombinants with multiple frameshift mutations to reveal the triplet nature of the genetic code; and inclusion of Taylor's discovery of phage Mu might have allowed an index entry under 'transposable elements'. Brock realistically evaluates the significance of the various contributions, and is not averse to minor demythologizing. For example Jacques Monod is said to have 'conveniently' failed to cite papers that pre-empted his views on permeability (elsewhere, Brock asserts, conveniently without documentation or specific examples, that 'many of the biochemical details that Monod hypothesized for allosteric proteins were incorrect'). The numerous often previously unpublished quotations by leading figures convey a particular sense of authenticity, and reveal some scientists, for example de Vries and Burnet, as especially far-sighted. Brock is not always convincing on scientific detail - a weakness in a book claiming to be 'a history of science rather than scientists'. What do we make of his statement that informational suppression could overcome the virulence of lambda mutants insensitive to repression,
when we know that virulence is an attribute of c/s-acting sites? Can lacZ +be said to be dominant over lacI-?Does he really mean that 'not all strains lacking the F-factor are F-'? How does 'crossing ... a mutant with multiple deficiencies [show whether it] is pleiotropic or merely represents a peculiarity in a biochemical pathway'? Why is Pseudomonas p y c a n e a (sic) repeatedly misspelt in its only incarnation in the book? Isn't it sloppy to invoke 'two genes, the att site and the int site' for integration of lambda into the chromosome? And a generally helpful restatement of the conventions for designating bacterial mutations is devalued by Brock's own failure to adhere to the system (e.g. araB-1 should be araB1 according to the published convention). The brief coda showing how recombinant DNA technology was founded on classical bacterial genetics might have exposed even further the significance of those early basic studies: for example, restriction enzymes are only a part - albeit crucial - of the battery of prokaryotic enzymes (ligase, DNA and RNA polymerase, kinase, etc.) that are supplied commercially to today's molecular biologists. It is a shame that these concluding remarks do not mention the continued flourishing of bacterial genetics, particularly in studies of nitrogen fixation, symbiosis, photosynthesis, pathogenicity, developmental biology (the list is long): work involving a plethora of bacterial genera, and so going full circle, or perhaps full spiral, to the kinds of organisms that intrigued those early, pre-genetical bacteriologists, but which were dropped for the dazzling charms of E. coli.
TIG FEBRUARY1991 VOL.7 NO. 2
S~a~
M~o
Laboratory of MolecularBiology, HillsRoad, Cambndge CB2 2QH, UK.
C~ John lnnes Institute, ColneyLane, Norwich NR4 7UH,UK.
The Emergence of Bacterial Genetics by ThomasBrock,ColdSpringHarbor LaboratoryPress, 1990.$55.00(xix+ 346 pages) ISBN0 87969350 9 This worthwhile book is a history of discovery in bacterial genetics up to the early 1960s. If I needed persuasion that such a book was necessary or timely, it was provided recently by an excellent postdoctoral bacterial geneticist who assumed that the Salmonella his genes must have been ordered by DNA sequencing: mapping by classical transduction is evidently almost lost in the mists of time! Brock recounts how well genetics got on without bacteria for the first four decades of the 20th century, before the subject reached a point of near-stagnation because of the virtual impossibility of doing biochemical studies on genes and gene action in higher organisms. Meanwhile, bacteriologists (struggling along without genetics) were discovering phages (in Shigella and micrococci) and lysogeny (in Bacillus megaterium), transformation (in Pneumococcus), and enzyme induction in yeast (an honorary bacterium), Enterobacter aerogenes and Bacillus subtilis. These discoveries acquired major significance only after Luria, Delbruck and Tatum showed that E. coli had genes that could be mutated, and when E. coli, in the hands of Joshua Lederberg, became a truly sexy subject for research. From then on bacterial genetics became - for many people (Broc~k included) - almost synonymous with the genetics of E. coli and its
H~EVIEWS
the subject, although unfortunately it does not extend its coverage to the genes encoding the hsps. Setting aside its potential for confusion, Stress Proteins in Biology a n d Medicine provides a thorough survey of the hsps and should greatly benefit the careful
reader interested in learning more about heat shock and its implications for biology.
phages. By the end of the period covered in this book, this had led to the first proper understanding of gene expression and its regulation, and the cracking of the genetic code; and some of the foundation stones of the recombinant DNA revolution were in place. Because it cannot date (unless history becomes obsolete) this book could presumably be bought and read for the indefinite future. Is it good enough? More or less, I think. The main topics are there, though one may cavil about omissions such as Fleming's discovery of penicillin (antibiotics were crucial to some of the key experiments that Brock describes), or the famous paper in which Crick et al. constructed T4 recombinants with multiple frameshift mutations to reveal the triplet nature of the genetic code; and inclusion of Taylor's discovery of phage Mu might have allowed an index entry under 'transposable elements'. Brock realistically evaluates the significance of the various contributions, and is not averse to minor demythologizing. For example Jacques Monod is said to have 'conveniently' failed to cite papers that pre-empted his views on permeability (elsewhere, Brock asserts, conveniently without documentation or specific examples, that 'many of the biochemical details that Monod hypothesized for allosteric proteins were incorrect'). The numerous often previously unpublished quotations by leading figures convey a particular sense of authenticity, and reveal some scientists, for example de Vries and Burnet, as especially far-sighted. Brock is not always convincing on scientific detail - a weakness in a book claiming to be 'a history of science rather than scientists'. What do we make of his statement that informational suppression could overcome the virulence of lambda mutants insensitive to repression,
when we know that virulence is an attribute of c/s-acting sites? Can lacZ +be said to be dominant over lacI-?Does he really mean that 'not all strains lacking the F-factor are F-'? How does 'crossing ... a mutant with multiple deficiencies [show whether it] is pleiotropic or merely represents a peculiarity in a biochemical pathway'? Why is Pseudomonas p y c a n e a (sic) repeatedly misspelt in its only incarnation in the book? Isn't it sloppy to invoke 'two genes, the att site and the int site' for integration of lambda into the chromosome? And a generally helpful restatement of the conventions for designating bacterial mutations is devalued by Brock's own failure to adhere to the system (e.g. araB-1 should be araB1 according to the published convention). The brief coda showing how recombinant DNA technology was founded on classical bacterial genetics might have exposed even further the significance of those early basic studies: for example, restriction enzymes are only a part - albeit crucial - of the battery of prokaryotic enzymes (ligase, DNA and RNA polymerase, kinase, etc.) that are supplied commercially to today's molecular biologists. It is a shame that these concluding remarks do not mention the continued flourishing of bacterial genetics, particularly in studies of nitrogen fixation, symbiosis, photosynthesis, pathogenicity, developmental biology (the list is long): work involving a plethora of bacterial genera, and so going full circle, or perhaps full spiral, to the kinds of organisms that intrigued those early, pre-genetical bacteriologists, but which were dropped for the dazzling charms of E. coli.
TIG FEBRUARY1991 VOL.7 NO. 2
S~a~
M~o
Laboratory of MolecularBiology, HillsRoad, Cambndge CB2 2QH, UK.
C~ John lnnes Institute, ColneyLane, Norwich NR4 7UH,UK.