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Darwin's Radio
Greg Bear. Ballantine Books, New York, 538 p., $6.99 (paperback).
Endogenous proviruses are a unique and fascinating aspect of retrovirus biology. These germline DNA elements, found in all vertebrates and many other species, provide a fossil record that can inform our understanding of virus-host coevolution in a way that is unavailable with any other pathogen. They can also act as agents of evolution, bearing responsibility for a wealth of genetic phenomena, ranging from activation or inactivation of genes to induction of spontaneous disease in certain animals (see p. 501). In this novel, science fiction writer Greg Bear creates an "evolutionary" role for certain human endogenous retroviruses (HERVs) quite different from what is known, and different from what any biologist would call evolution.
The plot develops as Kaye Lang, a virologist and biotech entrepreneur with forensic medicine training, is called to the Caucasus to examine the mysterious murders of pregnant women some years earlier. At the same time, Mitch Rafelson, an anthropologist with a somewhat checkered past, is led to an Alpine cave recently revealed by the thawing of a glacier. Within the cave are the mummified bodies of a Neanderthal couple, also victims of violence, along with a child evidently belonging to the couple, but clearly a modern human. By the end of the book, Mitch and Kaye have come together, only to find themselves in much the same situation as the prehistoric couple—exiled from their own society and hunted down because of the child they are carrying—with senior public health officials taking the part of the Neanderthal shamans.
As a graduate student, Kaye had become interested in HERVs, and had published a prediction that a set of scattered viral genes could be activated to recombine and form an infectious virus. As she soon learns, the violent deaths that she and Mitch had investigated were, in fact, an indirect consequence of exactly this phenomenon, now called SHEVA. SHEVA becomes a widespread plague infecting and affecting pregnant women. It is not spread in a conventional way, but rather is activated simultaneously in men in stable sexual relationships, apparently by a quorum-sensing mechanism in response to some type of group stress. Because of the bizarre way the virus induces miscarriage followed by impregnation of affected women, mass hysteria soon results, demonstrating that our modern society is no better equipped to deal rationally with an unknown plague than were the Neanderthals or the residents of remote Georgian villages. In contrast to the conventional wisdom of SHEVA as a disastrous plague to be contained and eliminated, Kate and Mitch, along with a few others, come to the conclusion that the "plague" is a part of a natural process. Instead of a resurrected pathogen, they reason, SHEVA was itself directing another step in human evolution.
Although the reader of this review will have difficulty accepting the oxymoronic premise of directed evolution, and may be irritated by some unnecessarily incorrect details, such as the size of the retrovirus genome, as a work of science fiction, Darwin's Radio works reasonably well. The microbiologist reader might also have liked to see further development of the few rather complex subplots (like the potential for the use of bacteriophage as antibacterial agents) introduced at length early in the book and then dropped completely. This reader would also have liked to see an explanation of how some of the key observations, like the discovery of SHEVA itself, were made. Despite its flaws, Greg Bear has made a unique and serious attempt to bring an arcane aspect of biology to a general audience, and has written a story that moves along in an entertaining and readable way, once the introductions are over.
John M. Coffin
Tufts University Medical School
Boston, Mass.Parasitic Nematodes (Molecular Biology, Biochemistry, and Immunology)
M. W. Kennedy and W. Harnett (ed.). CAB International Publishing, Oxford University Press, Cary, N.C., 2001, 486 p., $140.00.
While this book does not represent the entire field of parasitic nematodes, it does provide an exciting and comprehensive account of new research, potential new developments, and broadly applicable principles to cross-system research on both animal and plant parasitic nematodes. The authors are authorities in their subjects, are active researchers, and bring a broad perspective to their topics. The book is divided into five sections: Genetics and Phylogeny; Host Modulation and Manipulation-Making Themselves at Home; Specialist Products and Activities; Immunology and Immunomodulation; and Neurobiology. All chapters are well referenced and include relevant figures and photographs. In order to reduce the cost of the book, there are no color photographs; however, many of the color illustrations can be viewed and downloaded from the Internet.
There is a very comprehensive discussion of the recent advances in molecular phylogenetic analysis of the phylum Nematoda. Within the Nematoda, parasitism has arisen multiple times and the number of independent acquisitions of vertebrate parasitism predicted may still be an underestimate with multiple and complex adaptations being responsible.
There are discussions related to the role bacteria may play in pathogenesis of certain nematode infections such as filariasis; bacterial endosymbionts of both plant and animal pathogenic nematodes may play a very important role in nematode biology. These studies have implications not only for the pathogenesis of filarial diseases, but for treatment as well. Parasitism of/by nematodes has evolved in close association with bacteria; the fact that similar associations exist between bacteria and gall-forming insects may be coincidence, or may reflect some mechanisms involving host-plant modification.
There is excellent coverage of various immunological, biochemical and nucleic acid techniques, particularly PCR, PCR-RFLP, AP-PCR, RAPD, DGGE, and SSCP. The significance of diversity in populations of parasitic nematodes is also presented, using Strongyloides ratti as the model. There are extensive discussions related to the excretory/secretory and surface glycoproteins of Trichinella spiralis, as well as genetic reprogramming of mammalian skeletal muscle cells by this parasite.
The nematode cuticle is discussed and includes synthesis, modification, and mutants. This structure is a highly complex extracellular matrix, which comprises a complex mixture of collagens; however, proline isomerization, proline hydroxylation and ultimate cross-linking, together with the enzymes involved, may represent a weak link for these parasites. Chitinases of filarial nematodes are reviewed, with data suggesting that L3 chitinase has potential as a vaccine against filarial infective third-stage larvae. Information is also presented on acetylcholinesterase secretion, surface and secreted antigens of Toxocara canis, gut peptidases and proteins, the role of the pyruvate dehydrogenase complex during development of Ascaris suum, carbohydrates, and lipid-binding proteins.
The section on Immunology and Immunomodulation includes information on T helper cell cytokine responses during infection (induction, regulation, and effector function), gut immunopathology and immunomodulation by filarial nematode phosphorylcholine-containing glycoproteins. Nematode neuropeptides are reviewed, as is the neurobiology of nematode muscle. The discussion on membrane ion channels and electrophysiological techniques illustrates the possibilities of exploring the properties of some anthelmintics, as well as anthelmintics resistance.
Although this book is expensive, it contains fascinating and comprehensive information on a number of topics, which are relevant for those in academics, research, industry, and clinical parasitology. The chapters are well written and provide a broad perspective on the mechanisms of parasitism by nematodes and the similarities among both plant and animal parasites regarding the control of their tissue environments and defense reactions of their hosts. This book would be an excellent addition to any parasitology library, either at work or at home.
Lynne Garcia
LSG & Associates
Santa Monica, Calif.An Introduction to the Living Cell
VHS videotape. Written by Clyde S. White, distributed by Films for the Humanities & Sciences, Princeton, N.J., [(800) 257-5126, http://www.films.com], 29 minutes, 1998, 1 videocassette; $129.00.
Objective: The video has three main objectives: (i) to show the molecular structures of a living cell, (ii) to demonstrate how individual components of the cell work together in digestion, respiration, water regulation, and reproduction, and (iii) to highlight the role of organelles in keeping the cell alive.
Target audience: This film is suitable for a wide range, from high school to college and professional schools. High school students who are taking an introductory biology course can use this video as an adjunct to classroom material. College, medical, and allied health students can utilize it as an adjunct to the classroom as well as a review tool.
Description: This video shows how life evolved from simple to complex organisms. Life started from a single cell that evolved into multicellular and diverse organisms. Despite the diversity, single-cell and complex organisms share many properties such as the use of the same molecules to produce energy, grow, and reproduce. Cells are the basis for all life, come in different shapes and sizes, and perform different functions. Cells can also be responsible for diseases when they lose their ability to control growth. The video is divided in three broad sections outlining molecular structures, eukaryotic cells, and organelles. The segment on molecular structures provides a brief historic background of the cell theory followed by a look at cell diversity, specifically prokaryotes versus eukaryotes and their similarities and differences. The next portion concentrates on eukaryotic cells, the focal point of the video, and their three basic parts in addition to the differences and similarities between them in plant and human cells. Finally, the structure and functions of organelles are examined with the following components discussed: the nucleus, the control center; the cytoplasm, a complex solution; the endoplasmic reticulum, the transportation/highway system; the ribosomes, the primary sites for protein synthesis; lysosomes; mitochondria, the powerhouses; chloroplasts, the solar energy generators; the cytoskeleton, a steady framework; cilia and flagella; and plasma membrane.
Level of presentation: The video is very easy to understand, even by high school students.
Strength(s): A comprehensive review of the living cell is presented. The use of simple analogies, such as the endoplasmic reticulum as a system of connected highways of the cell, makes it easy to follow and conceptualize. The pictures and animations make the material lively.
Recommendations: The video fulfilled the objectives. I recommend purchasing the program as an adjunct material and a review tool.
Musau WaKabongo
Des Moines University-Osteopathic Medical Center
Des Moines, IAVoyage Inside the Cell
VHS videotape. Written by Christian Sardet, Laurent Larsonneur, and Andreas Koch, distributed by Films for the Humanities & Sciences, Princeton, N.J., [(800) 257-5126, http://www.films.com], 2000, 15 minutes, 1 videocassette; $89.95.
Objectives: The film sets out to show that the cell is the basic unit of life. Through mitosis, the cell can divide to become tissue, blood, skin, etc.
Target audience: The video is appropriate for college students with advanced knowledge of biology and genetics.
Description: The authors use the examples of a small and a big hormone to illustrate the complexity and the functions of the cell's components and mitosis. Both start at the cell membrane, a bumpy surface made up of fatty molecules and proteins. Some of these proteins trap and channel nutrients through the membrane, while others trap hormones that activate the cell. In the portion that presents the large hormone, the video demonstrates how the hormone stops at the protein receptors. This attachment sends messenger molecules to enzymes and organelles inside the cell (endoplasmic reticulum, mitochondria, cytoplasm, centrosomes, and nucleus). For example, when some messages reach the endoplasmic reticulum, its channels release calcium and trigger cell activities. The messenger molecules and calcium can also command the microfilaments to contract or relax and can instruct the cell membrane to recycle its components. In the next part, the small hormone is examined and begins with it entering the cell membrane. The hormone then passes through the cytoplasm and reaches the nucleus where it binds to a nuclear protein receptor before attaching to the target genes to deliver the message. This attachment triggers many activities: formation of micromachines to read and transcribe the genes, reading of the genetic code on the giant molecule of DNA, and duplication of the original DNA. When transcription is over, the RNA detaches from DNA, leaves the nucleus, and goes to the cytoplasm with the code to make protein that carries out the hormone's instructions.
The preparation for mitosis starts and many key players are involved: enzymes, structural proteins, chromosomes, centrosomes, sister chromosomes, spindle and microtubules, kinetochores, and contracting rings. In the end, two identical daughter cells that will keep growing and in turn dividing are formed.
Level of presentation: The material presented would be suitable to accompany upper-level courses at the college level.
Strength(s): The video presents beautiful illustrations of the structures of the eukaryotic cell (cell membrane, endoplasmic reticulum, mitochondria, nucleus, DNA, and mitosis).
Weakness(es): Subheadings are needed to introduce the next step in the process. Upbeat music could be very helpful.
Recommendations: The video fulfilled the objectives. I recommend purchasing the program as an adjunct to material for advanced students in biology.
Musau WaKabongo
Des Moines University-Osteopathic Medical Center
Des Moines, Iowa
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