J. Prolozoo/., 39(5), 1992, pp. 649-651 0 1992 by the Society of Protozoologists

BOOK REVIEWS

Ford, B. J. 199 1. The Leeuwenhoek Legucy. Biopress and Far- rand Press, Bristol and London. ISBN 1-85083-016-9. 185 pp. $47.50.

Any protozoologist/protistologist worthy of the name will be delighted to know that still another handsome book on the life and works of the father of our disciplines has appeared, this time from the quill of that irrepressible independent scientist/ microscopist and Fellow of Cardiff University, Brian J. Ford. Early in 198 I , Ford obtained permission from the Royal Society of London to examine certain files locked in their vaults, ma- terial virtually untouched for three centuries. As persistent and painstaking as a detective should be, young Brian discovered- among other things-some original, unopened packets of spec- imens attached to three early letters from our 17th century amateur Dutch microscopist. This led to comparative studies, exp Xriments, trips to The Netherlands, interviews, lectures, ar- ticles. and books, of which the present one is the most recent.

With incredible patience, the intrepid author (re)examined Leeuwenhoek’s precious bequeathments, not only with an orig- inal microscope used by Leeuwenhoek but also with modern light microscopy and scanning electron microscopy. Figures from these investigations are included in the book for all to see and, rightly, to admire. Detecting a tiny smear of blood on one of the sections of pith (yes, Leeuwenhoek was able to cut sections, with a razor blade, to a thinness of 30 pm!), Ford succeeded in demonstrating that the Father of Microscopy had indeed in- advertently bequeathed us a sample of his own erythrocytes, still recognizable more than 300 years later!

The second half of the scientific part of the book (earlier sections are devoted mainly to fascinating biographical material, including, interestingly enough, accounts about the late Clifford Dobell, surely the most popular biographer of Leeuwenhoek to date) treats the structure and construction of Leeuwenhoek’s microscopes-they were not all identical. Ford describes in de- tail the nine surviving instruments of the amazing Dutchman. Incidentally, presumably some 500 of them were made by the busy man from Delft over his lifetime, 26 of which were given to-and subsequently lost by!-the Royal Society.

The entire book, amply illustrated, represents a scholarly piece of work. Yet the pictures and drawings, combined with the clarity of the text, make possible an understanding and appre- ciation of Leeuwenhoek (and of Dobell and, last but not least, of Ford) by even the nonscientist. It is true that protozoologists will be a mite disappointed that none of their wee beasties made the pages of this particular publication, but apparently no cysts or skeletons ofthem survived by post (or the subsequent storage) across the English Channel, although diatoms and a few other algal protists did: but this is no fault of Ford’s.

Get the book, and curl up for a few evenings in recreation of the exciting times of our Founding Father 300 years ago. -JOHN 0. CORLISS, P.O. Box 53008, Albuquerque, New Mexico 87153.

Melkonian, Michael (ed.) 1992. Algal Cell Motility, Current Phycology 3. Chapman and Hall, New York. ISBN 0-4 12-0243 1 - 4. 236 pp. $45.00. Hardcover.

Algae are exceptional experimental systems for studying a wide range of biological phenomena including photosynthesis, photosensory transduction, circadian rhythms, pattern forma- tion, cell wall construction and the cell cycle. Nowhere is this truth more apparent than in the area of cell motility. Algal cells can have elaborate cytoskeletal organization that utilizes not

only those cytoskeleton components, microtubules and actin filaments, familiar to students of animal cell motility, but also less familiar cytoskeletal components such as centrin-containing fibrous rootlets and spasmonemes whose contraction is driven by calcium in the absence of ATP. Algal cells are the ideal place in which to study cell motility as regulated by light signals (chlo- roplast reorientation in order to optimize photosynthesis and changes in flagellar beat in response to changes in wavelength and intensity of light). Michael Melkonian has done an excellent job of bringing together, for the first time under one cover, the full range of motility phenomena exhibited by prokaryotic and eukaryotic algal cells. The six chapters in this small but pleasing volume cover gliding motility (Chapter l) , chloroplast move- ments (Chapter 2), cytoplasmic streaming (Chapters 2 & 3), flagellar motility (Chapters 4 & 5), and centrin-based cytoplas- mic contractility (Chapter 6). While the chapters in this volume range from the highly descriptive (Chapter 1 by Hader and Hoiczuk on gliding motility and Chapter 4 by Goldstein on flagellar beat patterns) to the highly mechanistic (Chapter 5 by Kamiya on the molecular mechanism of flagellar movement) with the rest falling somewhere in between, all of the chapters are well written and constitute valuable additions to this unique volume. I must confess that the chapters I found most satisfying to read were those by Kamiya on mechanisms of flagellar move- ment and Melkonian et al. on centrin-mediated cell motility.

Of all of the forms of cell motility described within this vol- ume, gliding motility is, by far, the most enigmatic and least understood and the only one to include both prokaryotic and eukaryotic organisms. While there are probably multiple mech- anisms of gliding motility, they tend to be characterized by whole cell movement in the absence of obvious cellular defor- mation and any obvious organelle responsible for the motility. I would be untrue to myself if I did not at least mildly protest the lack ofcoverage given by Hader and Hoiczyk to the literature on flagella-dependent whole cell gliding motility in Chlurny- dornonus.

As described in Chapters 2 and 3, actin and myosin are likely associated with bulk cytoplasmic streaming, some organelle translocations and chloroplast reorientation. Microtubules and dynein are, ofcourse, responsible for flagella-based algal motility (Chapters 4 and 5 ) and may have a role in some cytoplasmic organelle movements (Chapter 2). One of the newest and most interesting forms of cell motility is that of centrin-mediated contractile events involving fibrous rootlets. This unique kind of cell motility was initially discovered by Jeffrey Salisbury, Michael Melkonian and their colleagues using the alga Tetra- selrnis but has since been shown to be a very general phenom- enon among algae (as clearly brought out in Chapter 6). Throughout this book is woven the thread of regulation; in almost all cases ofalgal cell motility, calcium appears as a major component of the regulatory system.

In summary, this interesting and quite readable volume, with its excellent indexes, is a uniquely valuable resource for anyone interested in algal physiology, algal cell motility, or cell motility in general. That said, I can offer some modest criticism. The major drawback, from a production point of view, lies in the illustrations that are for the most part reproduced too small (especially in Chapters 1 & 2). If only the illustrations had uni- formly been enlarged to the width of the text (as they were in Chapter 6), it would have enhanced the appeal of this volume greatly. While the referencing of the chapters is generally very commendable and there is a singular lack of typos, I take ex- ception to the lack of reference to the work of Bob and Nina

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650 J. PROTOZOOL., VOL. 39, NO. 5, SEPTEMBER-OCTOBER 1992

Allen on streaming in Characean alga within the chapter by R. E. Williamson. The excellent review by Allen and Allen (Ann. Rev. Biophys. Bioeng. 7:497-526, 1978) goes uncited while the one reference to Nina Allen’s work that is included is inaccu- rately cited as Allen (1984) when it should be Allen (1974).- ROBERT A. BLOODGOOD, Anatomy and Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908.

Selander, R. K., Clark, A. G . & Whittarn, T. S. (eds.) 1991. Evolution at the Molecular Level. Sinauer Associates, Inc., Sun- derland, Massachusetts. ISBN 0-87893-8 19-2. 350 pp. $55.00, hardcover. $28.95, softcover.

This book contains an eclectic assortment of papers drawn from a conference on molecular evolution held in 1989. There are a total of 13 chapters.

In the first, Woese provides a rather free-wheeling and very readable account of early attempts to study bacterial phylogeny, and describes the ultimate abandonment of this topic by bac- teriologists in the pre-rRNA days. He then presents his now- familiar tripartite division of the living world and outlines some of the subdivisions in the two major prokaryotic groups. He regards the Archaea (the archaebacteria) as divisible into the Crenarchaeota and the Euryarchaeota. The crenarchaeotes are a group of hyperthermophiles, while the euryarchaeotes have a diverse array of phenotypes. The crenarchaeotes possess a va- riety of attributes which are somewhat eukaryote-like, and they may resemble the eukaryotic ancestor. What diverges at the base of the eubacteria is still an unsettled matter; it may be either the planctomyces or thermotogales lineage.

Seiander and coauthors review the classification of Salmo- nella strains. They compare the traditional methods of identi- fication and classification with their own putative phylogeny. These strains have historically been sorted out by a serotyping scheme which depends on the immunological response to bac- terial surface antigens: specifically, lipopolysaccharides and fla- gellar protein. They found discrepancies between the two sys- tems and conclude that there has been lateral transfer of genes encoding these antigens. This is hardly a surprise in view of the fact that it has been known since the 1950’s that many genes of Salmonella, including flagellar genes, are readily transferred from strain to strain by transducing phages. In fact, viral transduction was first discovered and explained in this Salmonella system, and these classic studies are frequently cited in books on virology and molecular biology. Furthermore, the authors’ phylogeny was constructed by using enzyme electrophoresis and “the av- erage-linkage method from a matrix of pairwise genetic dis- tances.” Few evolutionary biologists concerned with construct- ing phylogenies would regard this as a desirable method to use. Lateral transfer of the enzymes they used for constructing their trees may have occurred as well, and their methods are not adequate to reveal this. The extent to which their trees actually represent phylogeny at all is debatable.

In the third chapter, DuBose and Hart1 describe a way of studying the basis of selective constraints on macromolecules by using in vitro mutagenesis. For the past decade, it has been possible to introduce whatever mutations are desired into cloned DNA and study the effects of these changes on the function of the DNA sequence itself or of any gene products it produces. The authors went through this process with an Escherichia coli alkaline phosphatase gene. They found that many positions could be altered, but also identified some regions that must be con- served. The effects of changing these positions on enzyme ac- tivity could be directly observed. Surprisingly, they found that altering what had been regarded as a random coil interfered with

enzyme activity; theory is no substitute for experimentation. Comparing sequences in related organisms and experimentally altering sequences provide complementary ways of determining what selection pressures might be operating on a given gene sequence.

Crawford and Milkman superimpose tryptophan biosynthesis pathways on an rRNA-based phylogenetic tree and demonstrate the complex ways in which the pathways change over evolu- tionary time. They found evidence that there has been lateral transfer of the complete trp operon from one of the enteric bacteria into Brevibacterium lactofermentum, and they also found that homologous enzymes can enter into different pathways, replacing what is already there. The trp pathways, and by ex- tension other metabolic pathways, are evolutionary mosaics.

Yokoyama reviews the evolution of the viruses causing AIDS and their retroviral relatives. By using sequence comparisons he shows that the HIV viruses are lentiviruses and also shows that HIV I and HIV I1 have separate origins. Perhaps most interestingly, he calculates divergence times in his viral phylo- genetic trees and shows that the viruses responsible for AIDS have actually existed longer than previously suspected. Calcu- lations of this sort depend on so many extrapolations and as- sumptions that the actual values produced can’t be regarded as reliable. However, his general conclusion is supported by the discovery that blood samples taken as long ago as 1959 in Zaire have been found to contain antibodies against AIDS viruses.

Birky transfers some of the established mathematical models of population genetics to the study of organelle genome evo- lution. He points out the importance of a sort of intracellular random drift (depending on about half a dozen factors) in main- taining genetic homoplasy in the mitochondria and chloroplasts of an organism. He suggests that much of the population genetic theory for nuclear genes can be used for modeling organellar gene evolution with only minor modifications.

Clegg, Learn and Golenberg provide a straightforward sum- mary of chloroplast genome variation and evolution. Three complete chloroplast genome sequences are now known (from liverwort, tobacco and rice), many more have been mapped, and a variety of individual gene sequences have been deter- mined. Most chloroplast genomes have an inverted repeat, which seems to retard gene rearrangements. Chloroplast genes are not as subject to the recombination and conversion events occumng in the nuclear genes. The patterns of mutational change are comparatively simple ones, making restriction fragment length polymorphism (RFLP) patterns easier to interpret. As a result, chloroplast restriction site variation has turned out to be very useful in studying tracheophyte evolution. The general conclu- sions drawn to date will probably turn out to be less general once more is known about the chloroplasts of algae, however.

Charlesworth and Langley review the transposable elements found in the genome of Drosophila melanogaster. There are 50- 100 different types of elements in D. melanogaster, with a few to 60 of each type found per genome. Most are between 1 and 9 kb long. It turns out that many of the well-known mutations used in Drosophila genetics resulted from the movement of these elements into transcription units, rather than from the point mutations or deletions that one might expect to be more com- monly responsible for these morphological changes. These au- thors followed changes in the positions of transposable elements on individual chromosomes through many generations of flies by using in situ hybridization and restriction mapping. They found a very low rate of transposition, and conclude that little negative selection pressure is needed to preserve the equilibrium load of elements in a genome. They also conclude that the mean fitness of a fly population is hardly affected by the presence of these genomic parasites. The nature of the selective forces re-

BOOK REVIEWS 65 1

sponsible for blocking their spread through the genome are un- known, and it will be difficult to test the various possibilities because of the weakness of the force involved. Models of ge- nomic evolution predict that these elements should accumulate in regions of reduced crossing-over. They do accumulate near centromeres, but not near telomeres. Crossing-over is sup- pressed in both these regions, and existing models are not ad- equate to explain this discrepancy.

A more extreme type of genetic selfishness is discussed in the chapter by Wu and Hammer. They review the population ge- netics of three meiotic drive systems. In the sex-ratio condition of Drosophila, genes on the X chromosome cause gametes bear- ing the Y chromosome to degenerate after meiosis. The segre- gation distorter allele, also in Drosophila, prevents chromosome condensation during spermiogenesis. In male mice heterozygous for t , the t haplotype is transmitted to 95% of their progeny because sperm bearing the other allele are induced to undergo a premature acrosome reaction. These ultraselfish genes do not replace wild-type alleles because there is strong selection pres- sure against them. An intricate system of supressors, enhancers and lethals preserves the sensitive alleles in a population in a way that the authors compare to the scissors-paper-stone game. Although stretches of DNA involved in some of these phenom- ena have been located and cloned, the molecular bases of these activities are still unknown.

Kreitman reviews the mathematical expressions which may be used to quantify polymorphism. He suggests using sequences rather than RFLP-based estimates because of their greater ac- curacy. He uses the differences in observed and expected poly- morphism levels in 1 1 genes in Drosophila to infer the existence of a balanced polymorphism in one of the genes. He shows how the polymorphism would be distributed under different models of evolution and demonstrates that distribution patterns di- verging from a null model reveal the presence of selective forces.

The next two chapters, which overlap considerably, review the population genetics of the major histocompatibility complex in vertebrates. Both sets of authors set themselves the task of explaining how the extraordinarily high heterozygosity levels at these loci are maintained. While running through the alterna- tives, the first group of authors discard more possibilities than the second. However, both suggest that heterozygosity is selected for because heterozygotes are able to bind a greater variety of antigens and are therefore more resistant to disease.

In the last chapter of the book, Ross C. Harrison reviews globin gene evolution. He presents a vertebrate phylogenetic tree based on sequence differences within the genes, and also discusses the variety of gene duplications and rearrangements that have occurred at these loci during the course of evolution. He shows that the comparative study of gene arrangements reveals some of the mechanisms responsible for the movement of globin genes within a genome.

Given the diversity of topics covered within this book, there is probably something here for almost anyone interested in evo- lutionary biology. However, in aggregate, the chapters do not live up to the promise of the book‘s title. It is true that a few

chapters review entirely new areas in evolutionary biology that were opened up by developments in molecular biology. Others are simply the old problems of population biology (determining levels of heterozygosity, determining the intensity of selection, etc.) dressed up in Southern blots. It changes neither the prob- lems nor the results if the objects moved around by the formulas of population genetics are called “yellow eyes” or “3.4 kb bands.” This rechristening process doesn’t change the level of inquiry. The chapter by Birky, while entirely valid, doesn’t even go this far toward the molecular level. This gives the book a slightly dated tone; molecular biology has affected the study ofevolution more profoundly than in the rather pro forma ways in display throughout a lot of this book.-Jom GUNDERSON, Marine Bi- ological Laboratory, Woods Hole, Massachusetts 02543.

Simione, F. P. and Brown, E. M. (eds.) 199 1. A TCC Preservation Methods: Freezing and Freeze-Drying, 2nd ed. American Type Culture Collection, 1230 1 Parklawn Drive, Rockville, Maryland 20852. ISBN 0-9300009-41X. 42 pp. $45.00 U.S. and $50.00 foreign. Softcover.

A great amount of information is squeezed between the covers of this short book. While the manual is a compilation of the methods used at the ATCC for the low-temperature preserva- tion of viruses, procaryotic microorganisms, protists, cell cul- tures, and related materials by freezing and freeze-drying, it does have several pages of references to methods used elsewhere. The authors and editors have struck a good balance between dis- cussions of the general principles behind the methods and very detailed descriptions and illustrations of the equipment, sup- plies, and steps needed to accomplish particular tasks. The chap- ter on protozoa and algae, the one of most interest to readers of this journal, is a polished gem. There are currently over 100 protocols used for the preservation of the 1,100 strains of pro- tozoa and algae maintained at ATCC. These are summarized and generalized (preparation, ranges of three cryoprotectants used for protists, three controlled cooling and two uncontrolled methods, and three recovery methods) with little reference to particular genera. Particularly useful is a long table listing each genus which has been cryopreserved and the type(s) and con- centration of cryoprotectant(s) which has been used to recover members of the genus in the collection. There are also tables of protists which can be dried or freeze-dried and a briefdiscussion of the protocols to accomplish this and recover cells from these methods of preservation. There is a short chapter on safety and an address list of commercial suppliers for the equipment and supplies mentioned in the manual.

This manual is “must reading” for everyone who wishes to learn the methodology for cryoprotecting their strains of pro- tists. One can only guess at the reasons why a 42-page softcov- ered manual costs $45. At that price, the market will probably be quite hmited.-JoHN J. LEE, The City College of City Uni- versity of New York, New York, New York 10031.