Extracellular Matrix Influences on Gene Expression

cialist working in the area under discussion or to individuals involved in very closely related areas of research. Within these limits, both the clinical and basic immunologist will find the first of two of these articles to be extremely useful, while immunochemists will no doubt value all three. The study of histocompatibility antigens is becoming increasingly important since apart from their obvious role in histocompatibility itself, there has been a rapidly accumulating body of evidence to suggest that the cell membrane antigens play a fundamental role in conditioning some host reactions and that the genetic factors controlling the expression of these antigens are thus able to control much of the cell's internal environment and behavior. Most of the data presented in the article on antibody heterogeneity support the view that antibody variability is achieved by an evolutionary process. However, it is certainly not clear how antibody diversity is maintained in different species, and this important problem is reviewed. The significance of the finding that certain streptococcal vaccines can produce large amounts of restricted antipolysaccharide antibodies is discussed in detail, and the factors contributing to the occurrence of a monoclonal type of response are well outlined. Locked away in the mysteries surrounding the maintenance of antibody heterogeneity are many important genetic secrets and much important biological information ranging from the generation of diversity among antigen recognition units on the surface of lymphocytes to the nature of the stimulus that might provoke a malignant response. The third article clearly outlines the potential of yeast as a model organism for studying basic questions concerning nucleic acid synthesis. One of the great advantages of this organism is the ease with which genetic analysis can be performed, and it seems that this model will produce an in-depth investigation of the mechanism of DNA replication. In each of these articles the writing is disciplined but expressive, the references are both numerous and relevant, and in general this issue of this popular series can be highly recommended to those interested in the areas covered. The articles contain many good figures, and an excellent subject index is supplied.