Bacterial genetics in natural environments

Bacterial genetics in natural environments

~]OOK[I~E~EWS Essential Medical Genetics (3rd edn) by J.M. Connor and M.A.Fergus0n-Smith, BlackwellScientificPublications,1990. £12.95 (viii + 259 pa...

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~]OOK[I~E~EWS

Essential Medical Genetics (3rd edn) by J.M. Connor and M.A.Fergus0n-Smith, BlackwellScientificPublications,1990. £12.95 (viii + 259 pages) ISBN0 632 02872 6

Principles and Practice of Medical Genetics (2nd edn) edited by A.E.H.Emery and I).L.Rimoin, Churchill Livingstone,1990. £195.00 (xxi + 938 pages. Vol. 1: :cxii+ 2079 pages, Vol. 2) ISBN 0 443 03583 0 Medical genetics is a growth area. Not so much for medical geneticists, but for clinicians of many other specialities w h o have found in the past d e c a d e that 'their' disease has an inherited basis or is o p e n to analysis by genetic techniques. They are joined by similar numbers of nonclinical scientists who, after a PhD or postdoc on another system, find themselves working on the genetics of human disease. When I was at medical school, genetics was not on the curriculum. Things have changed since then, but even n o w most medics and biological scientists in the UK (except those w h o specifically study genetics) seem quite u n p r e p a r e d for their n e w interest, being unversed in basic genetic concepts such as linkage analysis. At a simpler level, students coming to the lab for the first time, and the growing army of genetic nurses and clinical associates, n e e d a manageable introduction to molecular genetics and c h r o m o s o m e biology relevant to what they will be doing. It was therefore g o o d to see that both these b o o k s have an excellent first section dew)ted to 'basic principles'. I was w a r n e d by the b o o k review editor to expect 'a coffee table book. and a b o o k that could be used as a coffee table'. Connor and Ferguson-Smith (the coffee table b o o k ) is a large-format, clear-type, brightly illustrated volume, and is a pleasure to read - __ but it is not lightweight: the essential information is there, accurate

and up to date. You could give this to the n e w c o m e r to your group and not be afraid of putting him or her off, although he or she might soon be asking for more detail. Emery and Rimoin (the coffee table) is sterner stuff: much more detail, small type, requiring some commitment to read, possibly not a starting point, but useful even for a fairly advanced readership. As befits a b o o k of essentials, the section on basic principles is roughly half of Connor and Ferguson-Smith. The rest of the b o o k deals with clinical genetics, but continues to emphasize the application of basic principles, rather than attempting to be a comp e n d i u m of clinical information. For the most part, 1 found this very successful, for e x a m p l e in chapters on prenatal screening, population genetics, and the use of Bayes' theorem. The presentation is excellent, and there are many tables and a whole chapter devoted to short notes on different single-gene disorders, which provide an easy reference for simple clinical information. It is easy to criticize chapters in one's own area, but the chapter on cancer genetics is probably the weakest in the book. The reason is betrayed by the suggested further reading: only three references, and all of them about c h r o m o s o m e abnormalities in leukaemias. In fact, the 'further reading' is generally a w e a k point:

For c ' & < Ls.t,"," ' and Bacterial Genetics in Natural Environments edited by John C. Frx and MartinJ. Day. Chapman and Hall, 1990. £44.00 (xii + 259 pages) ISBN !i -~1235630 9 The risk of releasing genetically engineered microorganisms (GEMs) into natural environments (either deliberately or accidentally) is a hotly debated issue in biotechnology, and a question central to the risk assessment is: 'What is the FIG.1( L'~ 199l VOL. ×o. 2"~('

for a b o o k that deliberately sets out to deal with principles, and which must h o p e to stimulate the reader to look further, the lists seem much too short. Emery and Rimoin is a 'Principles and Practice' book, and so 80% of its pages are devoted to a comprehensive clinical coverage of genetic disorders. For the most part, it seems to be a mine of useful information, well tabulated and extensively referenced. For a b o o k with over 150 contributors, the overall standard of chapters is well maintained and up to date, although there are a few gaps - for example, genomic imprinting gets only a passing mention, and that in the chapter on myotonic dystrophy. In my own field, the coverage is wide and mostly accurate, but could be criticized as sometimes long on clinical description and short on practical advice for management. The uncertain reward of b o o k reviewing is that you get to k e e p the books. This time round it has been worth it. Each of these b o o k s shouM in its way help to improve the understanding and practice of medical genetics.

B.A.J. PONDER CRC ftuman Qmcer Genetics Research Group. Department q/"Patboh~xr. UniversiO' ~!1 C~tmbridge. Tennts Court Road, Cambridge CB2 lOP. UK.

potential for gene transfer a m o n g bacteria in natural environments?'. That is the principal question addressed in this collection of papers from the Second European Meeting on Bacterial Genetics and Ecology (Bageco-2). Definitive answers are still lacking; however, the work presented in this volume suggests that environmental gene transfer can and does occur at detectable rates in a limited n u m b e r of circumstances. These findings also have more general implications, for example that gene transfer among naturally occurring bacteria may be an important mechanism of gene flow in bacterial evolution. The general approach in this field is to transplant gene transfer

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technologies that have been developed in vitro into systems that more closely approximate field conditions. In most of the studies presented here, microcosms of varying complexity stand in for the natural environment (partly due to restrictions on environmental release of GEMs). Conjugation (including mobilization of nonconjugative plasmids by conjugative plasmids) is considered to be a more likely mechanism of gene transport in soils and aqudtic systems than either transformation or transduction, so most investigators have tested for this form of transfer. Some relatively simple experiments involve inoculating lab strains of bacteria (e.g. Escherichia coli or a Pseudomonas species) as both donor and recipient in a microcosm and quantifying transconjugants. Others quantify transfer from lab strains to indigenous bacteria, an experimental design that is more relevant to the risk of re[easing GEMs. A particularly novel approach is Fry and Day's exogenous plasmid isolation procedure in which naturally occurring plasmids were isolated from aquatic biofihns in rifampicin-resistant lab strains of Psendomonas spp. The same approach could be used to characterize plasmids and plasmid tran>fer in other natural habitats as well. Another intriguing finding described in a chapter on transk'r in polluted soils is 'retromobilization' by 'hermaphroditic' plasmids. Hermaphroditic plasmk/s mediate conjugative transfer of genes from recipient to host and vice versa, that is, the bacterial hosts of these plasmids can act as both males a~d females. This retromobilization of genes can even occur betveeen bacteria that are widely separated taxonomically. An important feature is that genes can be captured from bacteria that are devoid of mobilizable or self-transfemd~le plasmids. Transfer frequencies xxcre generally higher in aquatic environ ments (to which five chapters are devoted) than in soils (allotted nine chapters). Conditions for transfer appeared most favorable in high nutrient environments (e.g. activated sludge or nutrient-amended soil). Although gene transfer is most difficult to demonstrate in n o n -

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sterilized, non-nutrient-amended soils, it has been detected using a broad-host-range plasmid introduced into soil in an E. coli strain engineered to be highly efficient at mobilization. This constitutes a 'worst case scenario'; the rates of transfer from actual GEMs should be much lower since they are presumably constructed with minimal transfer capabilities. Detecting gene transfer to indigenous microbes has been facilitated by DNA probes for marker genes, and this detection is possible even when the genes are not expressed in those cells. Further use of probes in this context will undoubtedly be advanced enormously by PCR (polymerase chain reaction) technok)gy, although PCR is only briefly mentioned in this volume. This book should be valuable both to molecular microbiologists with an interest in the environment and to microbial ecologists with a molecular bent. However, a broader audience might have been reached if the book had begun with a more general introduction. The first four chapters of the book do provide

some very useful background, especially the t w o chapters o n factors influencing gene transfer, but a more comprehensive explanation of terms and methods would have helped. Another criticism is a typical one for symposium books: while most of the chapters represent cutting-edge research by the major players in the field, a few contributions appear to be the preliminary data of newcomers or researchers in Lmgentially related areas. However if one accepts this disparity, the book is well worth reading; the editors also do an admirable job of drawing these disparate pieces together in a final summary chapter. The book presents tantalizing glimpses of the current state of knowledge of gene transfer in the environment and whets the appetite for future developments in the field.

THOMASL. I~rT Department of BioloRv. Neu,Mexico Tecb. Socorro. ,~3487801. USA.

In the other Trends journals A selection of recently published articles of interest to T/G readers • Insect control with genetically engineered crops by Karen J. Bmnke and Ronald t. Meeusen Trends in Biotechnology 9, no. 6, 197-201 • Good news and bad news about DNA fingerprinting by Patrick J. Weatherhead and Robert D. Montgomerie Trends in Ecology and Evolution 6, no. 6, 173--174 • The TPR snap helix: a novel protein repeat motif from mitosis to transcription by Mark Goebl and Mitsuhiro Yanagida Trends in Biochemical Sciences 16, no. 5, 173---177 • A common denominator linking glycogen metabolism, nuclear oncogenes and development by James R. Woodgett Trends in Biochemical Sciences 16, no, 5, 177-181 • How do retinal axons find their targets in the developing brain? by Mark Hankin and Raymond Lund Trends in Neurosciences 14, no. 6, 224-228 • Hereditary cerebral hemorrhage with amyloidosis - Dutch type: its importance for Alzheimer research by Joost Haan, John A. Hardy and Raymond A.C. Roos Trends in Neurosciences 14, no. 6, 231-235 •

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Polymorphism in human N-acetyttransferase - the case of the missing allele by Edith Sim and Dean Hickman Trends in Pharmacological Sciences 12, no. 6, 211-213

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