Dahlem Workshop Report – serie

3 There are other trends in the attempt to meld evolution and development which immodesty permits me to add. I have been concerned over the years with the selection forces which might have produced larger organisms and therefore a development of increasing complexity. This is nowhere more evident than in the multiple evolutionary origins of multicellularity and all the variety of developmental mechanics that have gone with it. (I discuss this and related themes in various places, but see especially The Evolution of Development (1958; (1)) and Size and Cycle (1965; (2)). To some degree these examples of the bringing together of evolu­ tion and development are exceptions. By far the most important historical trends in this century have been the success of in­ dividual disciplines. Embryology had its great flowering be­ ginning in the last century, coming to a climax with the work of Spemann on induction in the first two decades of this cen­ tury. Genetics has had an extraordinary continuing series of revolutions beginning with the rediscovery of Mendel and pro­ gressing through Morgan to the flash flood of molecular genetics and the structure of DNA. This flood was a flash only in the sense that it rushed upon us with amazing speed; its effects in the form of important and exciting work produced has not subsided and we are still in a peak period of molecular genetics.

will probably be clarified by the continued cooperative efforts of scientists such as those in the group that met in Berlin last September. The staff of Dahlem Konferenzen is responsible for making the meeting of this group memorably pleasant and pleasantly mem- orable. Dr. Bernhard's gifts of charm, organizational skill, and administrative toughness assured that the conference was run elegantly, smoothly, and decisively, even down to the choice of editors for this volume. Marie Cervantes-Waldmann performed minor miracles extracting manuscripts gently but persistently from the authors and in turning the typescripts into a book. The other staff members of Dahlem Konferenzen were unfailingly helpful even under trying circumstances. They will be well rememberedbyall who were fortunate enough to be asked to Berlin for the first week in September, 1980. Mineral Deposits and the Evolution of the Biosphere, eds. H. D. Holland and M. Schidlowski, pp. 5-30. Dahlem Konferenzen, 1982. Berl in, Heidelberg, New York: Springer-Verlag. Microbial Processes in the Sulfur Cycle Through Time H. G. TrUper Institut f. Microbiologie, Rheinische Friedrich-Wilhelms-Universitat, 5300 Bonn 1, F. R.Germany Abstract. Two microbial processes are involved in the sulfur cycle of the earth's biosphere: anoxic dissimilatory sulfur oxidation by phototrophic bacteria and dissimilatory sulfate reduction by sulfate-reducing bacteria. In the presence of oxygen at chemoclines and redoxclines dissimilatory sulfur oxidation by chemolithotrophic bacteria (Thiobacillus, Beg- giatoa, and others) occurs. In addition, dissimilatory sulfur reducing bacteria participate in the sulfur cycle.

need for an interdisciplinary approach to research, although scientifically desirable and laudable, is not easily met by the individual investigator, a statement which I must now qualify lest it be taken as a faint-hearted view of the problems which confront us in this or any other field of disease-orientated re­ search. In recent years the growth and scope of MS research parallels, in fact reflects, that which has occurred more generally concern­ ing research at all levels of complexity into the nature and modes of operation of the nervous systems of different animals. With respect to these developments Cowan (2) has observed that "this has led to the gradual emergence of a new, interdisciplinary ap­ proach to the study of the nervous system which has come to be known as Neuroscience. " At the center of neuroscience stands man striving to comprehend hirnself, not only in terms of the nuts and bolts of his own ner­ vous system and that of lower animals, but perhaps preoccupied most of all with the higher level nervous functions of perception, volition, cognition, and mentation, which characterize his "self. " The investigation of these processes depends ultimately on re­ search on man hirnself and the analysis of these processes in depth often must wait on Nature's own experiments to provide, through disease, the chance anatomical or biochemical lesions which dissect human behavior and expose the residual functions for scientific study.

the oleic acid on a live and wriggling sister or mother and refrain from evicting her from our hive. But does the occur­ rence of unintelligent behavior suffice to demonstrate the total absence of mental experience under any circumstances? Ethologists from some distant galaxy could easily discern ex­ amples of stupid and maladaptive behavior in our own species. But do instances of human stupidity prove that none of us is ever consciously aware of what he is dOing? No available evi­ dence compels us to believe that insects, or any other animals, experience any sort of consciousness, or intentionally plan any of their behavior. But neither are we compelled to believe the contrary. In areas where data are few and of limited rel­ evance, dogmatic negativity can easily limit what scientists even try to investigate, and thus perhaps delay or prevent im­ portant insights and discoveries. Many of the participants agreed that a good starting point would be to consider what we know of our own thinking, subjec­ tive feelings, and consciousness, and then move on to inquire whether other species experience anything similar. Such an ap­ proach was once considered fallaciously anthropomorphic. But it seems now to be widely if not universally recognized that this is a serious objection only if one has already assumed in advance that conscious thinking is uniquely human, and the accu­ sation of anthropomorphism is then merely a reiteration of the prior conviction.

normal and pathological mineralization in vertebrates but also with the interesting problems involved in the formation of in­ tracellular deposits of calcium oxalate in plants. Here cal­ cium carbonate and silica may also be involved in the mineral­ ization processes. Calcium carbonate is an important component in the formation of mollusc and avian shells. The observation that both calcite and aragonite may be formed in biogenic cal­ cium carbonate raises important questions as to what factors control the formation of the final mineral phase. There is little doubt that thermodynamically less stable phases may be kinetically stabilized for long periods of time by other mole­ cules present in vivo. In normal mineralization, calcium salts may initially be deposited both within the cells and extracel­ lularly. In the latter case, the role of matrix vesicles and the ways in which the matrix components might control mineral­ ization were especially emphasized. There is clearly a need for more structural and functional information involving cells, matrix components, and their associated crystals. The develop­ ment of further techniques involving mutants, chromofluors, and fixatives for preservation of tissue and the ions present in vivo was recommended. In dealing with abnormal and pathological mineralization, the Workshop concentrated on urolithiasis, gout and pseudo-gout, and the formation of dental caries. Discussions based on the influence of media of low pH on mineral surfaces highlighted some of the factors of importance in controlling crystal dis­ solution.

5) To what extent do events occurring during regeneration re­ semble those seen in development? Questions like these remain open, particularly in relation to the mammalian central nervous system and to the effects of lesions or disease. The first chapters of this volume are concerned primarily with normal and abnormal development of the nervous system. New concepts have emerged over the past few years as a result of experiments made on the development of the higher nervous system in mammals. Thus, the principles of cell death, competition, selective retraction of specific processes, and the effects of abnormalities on the development of the rest of the system have now been extensively investigated. In addition, considerable information is available about biochemical changes during normal and abnormal development in the human. At the other end of the scale, in invertebrates it is now possible to follow cell lineage and to define the origin and fate of a sin­ gle neuron of known function together with its processes. While an understanding of development is clearly important for studying basic mechanisms of repair and regeneration, one cannot expect the processes to be identical or even comparable in the two situations. For example, cell migration, guidance by radial glial fibers, selective cell death, and the critical periods for competition, sprouting, and retraction observed in the visual system can hardly playa part in repair.

for the design of control programs; in extreme cases (as dis­ cussed below, by Fine et al. , this volume, and elsewhere) it can happen that immunization programs, although they protect vaccinated individuals, actually increase the overall incidence of a particular disease. The possibility that many nonhuman animal populations may be regulated by parasitic infections is another topic where it may be argued that conventional disciplinary boundaries have retarded investigation. While much ecological research has been devoted to exploring the extent to which competition or predator-prey interactions may regulate natural populations or set their patterns of geographical distribution, few substan­ tial studies have considered the possibility that infectious diseases may serve as regulatory agents (1,8). On the other hand, the many careful epidemiological studies of the trans­ mission and maintenance of parasitic infections in human and other animal populations usually assume the host population density to be set by other considerations, and not dynamically engaged with the disease (see, for example, (1,2)). With all these considerations in mind, the Dahlem Workshop from which this book derives aimed to weave strands together -- testing theoretical analysis against empirical facts and patterns, and identifying outstanding problems -- in pursuit of a better un­ derstanding of the overall population biology of parasitic in­ fections. For the purpose of the workshop, the term "parasite" was de­ fined widely to include viruses, bacteria, protozoans, fungi, and helminths.

3 and a fraction mayor may not respond to treatment. On the behavioral level, animal research shows that a variety of experimental conditions can induce de­ pression. The same is true in the field of treatment, where pharmacologically highly different drugs can equally alleviate depression in animals and hu­ mans. The question as to whether this is due to a heterogeneity of depressive subjects based on different pathogenetic mechanisms is open to discussion. We can look for common features of all possible causal factors in the hope of finding a single basic mechanism. Many divergent findings may also be ex­ plained as peripheral changes of a highly complicated dynamic system. In the field of psychopharmacology, a circular reasoning has become evident in the sense that originally the clinical antidepressive response was founded on empirical grounds only. In a second step, an attempt was made to characterize some clinically active compounds pharmacologically, and in a third, further compounds were developed based on aspects of the pharmaco­ logical profiles. Moreover, the post hoc development of a pharmacological screening method has the serious disadvantage of delaying breakthroughs into new fields.

they belong. Do communities have rights, indeed even an existence, which are not merely the hypostasis of the individual rights and existences collected in them? This conflict is then more striking as it was a conscious decision of the or­ ganizers of the workshop to focus attention on what might broadly be called liberal democracies: those societies which share a commitment to the princi­ ples of democratic participation, to the right of equal concern and respect of all members of the community, and to the basic liberties of association, ex­ pression, and thought. Ours was not the smug premise, however, that every so­ ciety which proclaims these principles is sufficiently or even truly devoted to them. But we did assume that we would have enough to do if we explored the implications of these widely shared ideals for the topic of linguistic, ethnic, and national minorities as these problems arise in societies where an appeal to them is not an empty gesture. The nations from which our participants were drawn are societies in which appeal to these principles has some point. They are all societies in which the efforts of politicians and the intelligence of schol­ ars need not be devoted exclusively to the tactical issues of winning some mod­ icum of respect for basic human rights from unwilling regimes. And yet all these societies have experienced significant difficulty in determining what the concrete meaning in actual situations of these general principles might be.

of metal interactions with subcellular biochemical systems usually either are metabolites of the system affected (porphyrinurias) or represent some specific function of a cellular system being impaired (proteinurias). One typically finds a continuum of symptoms, from the subtle or so-called "no effect" bio­ chemical and physiological indicators of exposure to severe clinical disease and death. This continuum is the basis of much of the controversy since many health officials follow the traditional practice of applying the "threshold­ health-effect" concept in evaluating the problems of environmental exposure to metals. The past decade or so, however, has seen a vast increase in our understanding of the effects of elevated concentrations of toxic metals in local populations and ecosystems. At the same time, there is a growing awareness that the effects of the metals which occur naturally in the environment must be distinguished from those imposed by the pollutant fraction. This point was amply document­ ed in a recent study of cadmium intake and cadmium in a number of human tissues in Sweden, Japan, and the United States, which showed fairly conclu­ sively that the background exposure in Japan was about threefold higher than in the other two countries (2). One immediate implication is that any health ef­ fect studies of cadmium in Japan using control groups within that country are liable to underestimate the difference between the exposed and the control groups simply because of the the high "background" intake.

3 of the experience of the last few generations. The group of happily unexperienced events includes large bolide impacts with the Earth. The evidence for the occurrence of such impacts at intervals of some tens of millions of years is quite convincing, and Lyell stands admonished by Hamlet: "There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy. " The role of bolide impacts on the history of life during other portions of the Phanerozoic Eon is less clear (see Raup and Fischer, both this volume), and catastrophic changes unrelated to extraterrestrial processes may have been important (see Holser, this volume). Changes in the later Precambrian biota are still difficult to interpret, in part because the preservation of soft-bodied animals from this period of Earth history is so unusual (see Seilacher, this volume). During the past billion years or so, bolide impacts have exerted a significant effect on the Earth's surface and its inhabitants, but not on its interior. The 3800 Ma rocks at Isua in West Greenland are the oldest terrestrial rocks that are currently available for inspection (see Dymek, this volume). They contain abundant evidence for the operation of chemical and physical processes that are similar to those of the present day. This situation could not have prevailed during the entire 700 Ma preceding the formation of the Isua rocks.

and how the known vertebrate homologues of these genes are expressed normally in differentiation and proliferation pathways as well as abnormal­ ly in well-defined lymphomagenic and other oncogenic pathways. What emerged from this meeting are a better understanding of the evolution of these gene systems themselves and an elucidation of simpler systems open to more rapid genetic and molecular genetic analysis to reveal the normal functions of these genes and their gene products. Thus we sought new answers to several old questions concerning differenti­ ation, proliferation, and neoplastic transformation. We gathered together in an unusual format - that of the unique Dahlem Workshops - not just to reiterate data which has recently emerged but to think about how these findings might lead to new approaches for the understanding and therapy of the leukemias and lymphomas. We deliberately chose experts from several different disciplines, ranging from the clinicians who diag­ nose, describe, and treat these maladies, to the molecular geneticists trying to reduce the analysis of the problem to its simplest variables in the simplest systems possible.

P. Marler* and H. S. Terrace** *The Rockefeller University Field Research Center Millbrook, NY 12545 **Dept. of Psychology, Columbia University New York, NY 10027, USA For the first half of this century, theories of animal conditioning were regarded as the most promising approach to the study of learning - both animal and human. For a variety of reasons, disillusionment with this point of view has become widespread during recent years. One prominent source of disenchantment with conditioning theory is a large body of ethological observations of both learned and unlearned natural behavior. These challenge the generality of principles of animal learning as derived from the intensive study of a few species in specialized laboratory situations. From another direction, the complexities of human language acquisition, surely the most impressive of learned achievements, have prompted developmental psychologists to doubt the relevance of principles of animal learning. Even within the realm of traditional studies of animal learning, it has become apparent that no single set of currently available principles can cope with the myriad of new empirical findings. These are emerging at an accelerating rate from studies of such phenomena as selective attention and learning, conditioned food aversion, complex problem­ solving behavior, and the nature of reinforcement. Not very surprisingly, as a reaction against the long-held but essentially unrealized promise of general theories of learning, many psychologists have asked an obvious question: does learning theory have a future? 2 r. Marler and B. S.

usage of the terms substrate and substratum. A substrate (pI.: substrates) is a material utilized by microorganisms, generally as a source of energy. A substratum (pI.: substrata) is asolid surface to which a microorganism mayattach. REFERENCES (1) Marshall, K.C. 1976. Interfaces in Microbial Ecology. Cambridge, MA: Harvard University Press. (2) ZoBell, C.E. 1943. The effect of solid surfaces upon bacterial activity. J. Bacteriol. 46: 39-56. Standing, left to right: Paul Rutter, Rolf Freter, Mike Silverman, lan Robb, Hinrich Mrozek, Frank Dazzo, David Gingell Seated, left to right: Garth Jones, Stanislawa Tylewska, Staffan Kjelleberg, Ellen Rades-Rohkohl, Kevin Marshall Microbial Adhesion and Aggregation, ed. K.C. Marshall, pp. 5-19. Dahlem Konferenzen 1984. Berlin, Heidelberg, New York, Tokyo: Springer-Verlag. Mechanisms of Adhesion Group Report P.R. Rutter, Rapporteur F.B. Dazzo H. Mrozek R. Freter E. Rades-Rohkohl D. GingeIl I.D. Robb G.W. Jones M. Silverman 8. Kjelleberg 8. Tylewska K.C. Marshall INTRODUCTION The subject, Mechanisms of Microbial Attachment, has proved to be a fertile sour ce of argument between both microbiologists and physical chemists.In order to find common ground for discussion, the group endeavored to come to a consensus regarding a number of definitions pertinent to the subject. Some of these are described in the text and others will be found at the end of this report.

free from any of the overtones that often constrain professional fisheries meetings. The present volume is the result. This volume aims to be useful as an appraisal of the state of the art by a mixed collection of insiders and outsiders. Most interestingly, I think, it aims (especially in the four group reports) to identify some of the major areas of unresolved controversy and some of the major questions yet unanswered. I see the book as essentially a tentative statement - often by several dissonant voices - about directions in which we may be heading; the book is emphatically not a canonical utterance on how to do things. It is intended to stimulate, not to codify. Following the usual Dahlem Workshop format, the discussions were organized under four themes. Although crisp demarcation is not possible, the first two themes broadly deal with biological aspects of the dynamics of single populations and the dynamics of systems with many species. The later two themes take up questions of management under uncertainty and multispecies management. In all this, the word "fish" is interpreted broadly to include such taxonomically varied beasts as whales, shrimp, crabs, shellfish, and squid, along with fish in a strictly zoological sense.

Report, the editors replaced the term "speciation" wherever it occurred by "identification and quantification," or "description of abundance," or "reactivity," or "transformation" of a chemical species, according to whichever one of the four meanings the author had evidently meant to convey. In line with the Dahlem Workshop Model, this Report comprises the background papers written in advance of the meeting on the current status of problems in environmental research and on advanced analytical tech­ niques for the identification and quantification of chemical species, as well as the group reports summarizing the results of the discussions held during the meeting. Each group report was prepared during the meeting by one "rapporteur" with the help of members of that group and finalized by the rapporteur (listed as the first author of the group report) after the meeting, taking into account both verbal comments made during the presentation of the reports in the plenary session at the end of the workshop and written comments received afterwards.

very important, especially the comparison of vertebrate and invertebrate transduction mechanisms. The workshop was very successful and the outcome of the discussions proved it worth the effort. To no small extent has that success been made possible by Dr. Silke Bernhard who with a combination of authority and charm together with her extremely efficient and dedicated staff organized this workshop, providing the conditions and framework for a scientific debate of outstanding quality in a friendly and pleasant atmosphere. The great majority of participants were also very committed to making this workshop successful. Besides the reports of the four discussion groups, this publication contains the background papers which were revised by the authors partly as a result of suggestions of some participants. I hope this book will give a fair overview of the state of our knowledge of research in visual transduction. It was a pleasure to edit, especially because of the friendly and very efficient commitment of K. Geue, J. Lupp, and A. Eckert and the cooperativeness of most of the contributors. Particularly I would like to acknowledge gratefully the extensive efforts and patience of the four rapporteurs, M.L. Applebury, W.H. Miller, W.G. Owen, and E.N. Pugh, Jr., in compiling, writing, and revising the group reports. REFERENCES (1) Altman, J. 1985. Sensory transduction, new visions in photoreception. Nature 313: 264-265. (2) Hagins, W.A. 1972. The visual process: Excitatory mechanisms in the primary receptor cells. Ann. Rev. Biophys. Bioeng. 1: 131-158.

hurdle will be in the latter area. The technological hurdles will be formi­ dable but will not limit what happens: once the basic ideas are available, the technology will be developed. The unique part of biotechnology will be to imagine what the possibilities are. There was a discussion in several of the groups on the problems of intro­ ducing a novel science into a social and economic context. What biotech­ nologists are learning on this matter is not novel, although that does not make it any less important or difficult. People in the development of elec­ tronics and computers, in the pharmaceutical industry, and in many other types of industry that have grown from university research have had to face these problems in the past. It is the old situation of having to reinvent the wheel again and again. There is one aspect on which biotechnology seems to have handled this inherent difficulty better than some of our predecessor technologies: the people in the biotechnology companies by and large take a rather academic approach to free communication with one another at meetings such as this and open publication of many of their basic findings in the literature. This seems unique and certainly is different from the experience of the recent Silicone Valley Industry, which in other ways tries to emulate an academic environment, but not in open and free publication.