Genetics a molecular approach

Genetics a molecular approach

~OOK/EVIEWS Mutation,Developmental Selection and PlantEvolution EdwardJ. Klekowski,Jr, ColumbiaUniversity press, 1988.$55.00(xi + 373 pages) ISBN0 23...

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Mutation,Developmental Selection and PlantEvolution EdwardJ. Klekowski,Jr, ColumbiaUniversity press, 1988.$55.00(xi + 373 pages) ISBN0 231 065280 Mutations, whether advantageous, neutral or deleterious, are an everpresent possibility and have to be dealt with by all organisms. The pattern of the life cycle must play a pivotal role in the strategies of coping with these events. Plants do not sequester a germ line and differentiate their gametes from cells that have already participated in the generation of the somatic body of the plant. Thus they are susceptible to the accumulation of somatic mutations that have the potential to be transmitted between generations. Also, since some plants live for a few weeks while others survive for thousands of years, a range of strategies will be needed to cope with the consequences of somatic mutations. The focus of this interesting and stimulating book is on the role of multicellular systems in the propagation or elimination of mutagenic events, in both the vegetative and the reproductive phases of the life cycle. The sections dealing with the vegetative phase of the life cycle are concerned with the many types of structure that the meristem can have, and the fate of cells within that meristem, through the life cycle of the organism. How the structure, size and organization of the meristem affects the fixation or loss of individual meristematic cells that have mutated is covered descriptively and mathematically. These sections give a feel for the long-term consequences of various meristem organizations and provide cogent examples of organisms in which the different types are found. Having considered the fate of individual cells, the relationship between cell and organismal fitness is detailed, along with the ways in which selection can act on the whole organism, especially during the reproductive phases and

immediately after fertilization. Again, the descriptive passages on the consequences of various structures and strategies are stabstantiated by the appropriate mathematical treatment. Woven through this fabric is a discussion of the ways in which mutations may arise and how they may be ameliorated at the molecu-. lar level. The basic premise of this discussion is that mutations are rarely advantageous and their presence must be minimized. However, the authors conclude that although may characteristics of vascular plant life cycles can be interpreted as functioning to preclude the transmission of harmful mutations, the effectiveness of the selection is unclear since many examples of such transmission have been described. On this note, since transmission of mutations does occur, the dicussion turns to genetic load and its importance in various systems, especially in relation to longevity. The examples used to illustrate the different types of organization and development are not all drawn together; thus it is not possible to determine the relative importance of the various mechanisms within groups of plants. If such a side-byside comparison is not a realistic possibility with the current data and examples, attention could have been drawn to those pairs or groups of plants in which further work could be done to demonstrate the importance of the different levels of organization. This would have rounded out the discussion and led more directly to a formulation of the appropriate approaches for future studies. The relationship between the topics included in the title remains tantalizingly elusive and a reading of this book should provoke much thought about the subject. Clearly, we have yet to understand fully *..hemany facets involved in maintaining genetic integrity - ff this is, in fact, a desirable goal - without a sequestered germ line and over what can be immense periods of time.

CdL Oam Department of BiologF, Caze WesternReserve University, Cleveland, OH 44106, USA.



Genetics a Molecular Approach by TA. Brown,Vanl~ostrandReinhold (International), 1989.£16.95(xvii+ 387 pages) ISBN0 278 00041X An educated reader naive to the field of genetics will find Brown's Genetics a Molecular Approach enthralling. Brown writes in a simple, clear prose that makes the complex new language of molecular genetics easily accessible to the novice. Explanations of terms are cogent, diagrams are clear, and the glossary at the end of this text proves essential for relieving a student's anxieties upon learning a new language. One wonders why more comprehensive genetics textbooks fail to include such a powerful educational device. In an introductory course of study without a series of clear, basic lectures to complement a more comprehensive text, Brown's text is indispensable. Even together with a clear series of lectures, Genetics a Molecular Approach can only help students acquire a fundamental understanding of this evolving field. It is a particulany useful text for introducing advanced students from related fields of science to the concepts of molecular genetics. The author does not purport to provide other than an introductory account, and acknowledges that he must pay a price for attempting to strike a balance between simplification and understandable presentation. Thus, for the expert, many of the explanations in this text will appear somewhat oversimplified. On the other hand, for the novice, this text hints at wonders that require further exploration. For the teacher of an introductory molecular genetics course, as I have been for the past six years, this text is a necessity.

Pint Yot~vat~ California Institute of Biological Research, 11099 North TorreyPines Road, LaJolla, CA 92037, USA.