The Cell Biology Of Sponges

Modem biology owes much to the study of favorable model systems which fa cilitates the realization of critical experiments and results in the introduction of new concepts. Examples of such systems are numerous and studies of them are regularly recognized by the scientific community. The 1983 Nobel Prize in Med icine and Physiology is a magnificent example in which com plants served as the experimental model. In a manner somewhat more modest, other biological systems have attracted recognition due to their critical phylogenetic position, or indeed because of their uniqueness which distinguishes them from all other organisms. Assuredly, among the whole assemblage ofliving organisms, sponges stand out as worthy of interest by scientists: they are simultaneously models, an important group in evolution, and animals unlike others. As early as the beginning of this century, sponges appeared as exceptional models for the study of phenomena of cell recognition. Innumerable works have been dedicated to understanding the mechanisms which assure the reaggregation of dissociated cells and the reconstitution of a functional individual. Today, re search on these phenomena is at the ultimate, molecular level. Through an as semblage of characteristics the sponges are, based upon all available evidence, the most primitive Metazoans. Their tissues-perhaps one can say their cell groups-are loosely assembled (they possess no tight or gap junctions), cell dif ferentiation appears highly labile, and they do not develop any true organs. But, they are most certainly Metazoans.

Sponges (phylum Porifera) are known to be very rich sources for bioactive compounds, mainly secondary metabolites. Main efforts are devoted to cell- and mariculture of sponges to assure a sustainable exploitation of bioactive compounds from biological starting material. These activities are flanked by improved technologies to cultivate bacteria and fungi which are associated with the sponges. It is the hope that by elucidating the strategies of interaction between microorganisms and their host (sponge), by modern cell and molecular biological methods, a more comprehensive cultivation of the symbiotic organisms will be possible. The next step in the transfer of knowledge to biotechnological applications is the isolation, characterization and structural determination of the bioactive compounds by sophisticated chemical approaches.

One of the major questions in the evolution of animals is the transition from unicellular to multicellular organization, which resulted in the emergence of Metazoa through a hypothetical Urmetazoa. The Comparative Embryology of Sponges contains abundant original and literary data on comparative embryology and morphology of the Porifera (Sponges), a group of 'lower Metazoa'. On the basis of this material, original typization of the development of Sponges is given and the problems concerning origin and evolution of Porifera and their ontogenesis are discussed. A morphogenetic interpretation of the body plan development during embryogenesis, metamorphosis and asexual reproduction in Sponges is proposed. Special attention is given to the analysis of characteristic features of the ontogenesis in Porifera. The book pursues three primary goals: 1) generalization of all existing information on individual development of sponges, its classification and a statement according to taxonomical structure of Porifera; 2) revealing of heterogeneity of morphogenesis and peculiarities of ontogeneses in various clades of Porifera, and also their correlations with the organization, both adult sponges, and their larvae; 3) revealing homology of morphogeneses in both Porifera and Eumetazoa, testifying to the general evolutionary roots of multicellular animals, and peculiar features of sponges' morphogeneses and ontogenesis. This book will be of interest to embryologists, zoologists, morphologists and researchers in evolutionary biology.

Aspects of Sponge Biology is the result of a symposium about sponge biology held in Albany, New York in May 1975. The symposium not only presents investigations, but also problem areas in the field of sponge biology. This book therefore shows that sponges are a very challenging and untouched subject area for future studies. This book is divided into three major parts, wherein the first part introduces and discusses sponge biology. The introduction and discussion include sponge biology principles, perspectives, and problems. The next two parts discuss cell and development biology, taxonomy, and ecology. Part 2 deals with several topics of the cellular aspect, including an analysis of reproduction in sponge populations and cytochemical studies of connective tissues in sponges. This part also looks into the cytological abnormalities in various normal and transformed cell lines. Part 3 describes the different types of sponge in their various habitats. Sponge feeding mechanisms, ecological factors controlling sponge distribution, and zoogeography of Brazilian marine Demospongiae are also discussed in this part. This book will be of important value to biology students and teachers. Specialists including zoologists, ecologists, comparative physiologists, and biologists will also benefit from this book.

The sponge has attracted attention as one of the first animals to evolve multicellular organization. The sponge also interests scientists because it provides excellent research material in molecular phylogeny, allowing the process of animal diversification to be probed at the molecular level. Additionally, researchers have discovered in sponges certain bioactive substances with unique antibacterial and anticancer properties of great interest in medical and pharmaceutical science. Sponge Sciences presents the most up-to-date information on all areas of sponge research, with emphasis on taxonomy, molecular evolution, developmental biology, and natural products chemistry, as well as the biology of freshwater sponges. It also provides new findings in the morphology, cell biology, physiology, ecology, and biogeography of sponges. The papers compiled here are contributed by world-renowned sponge scientists.

The authors "have intended to make the forefront of sponge research easily accessible to the nonspecialist, illustrating the state of the art of the field,and presenting current controversial issues. For the specialist, we wanted this monograph to be a handy, valuable update on the most recent advances in sponge science."--p. x

Concepts of Biology is designed for the single-semester introduction to biology course for non-science majors, which for many students is their only college-level science course. As such, this course represents an important opportunity for students to develop the necessary knowledge, tools, and skills to make informed decisions as they continue with their lives. Rather than being mired down with facts and vocabulary, the typical non-science major student needs information presented in a way that is easy to read and understand. Even more importantly, the content should be meaningful. Students do much better when they understand why biology is relevant to their everyday lives. For these reasons, Concepts of Biology is grounded on an evolutionary basis and includes exciting features that highlight careers in the biological sciences and everyday applications of the concepts at hand.We also strive to show the interconnectedness of topics within this extremely broad discipline. In order to meet the needs of today's instructors and students, we maintain the overall organization and coverage found in most syllabi for this course. A strength of Concepts of Biology is that instructors can customize the book, adapting it to the approach that works best in their classroom. Concepts of Biology also includes an innovative art program that incorporates critical thinking and clicker questions to help students understand--and apply--key concepts.