It is also possible that contractile vacuoles originate by some form of phase separation not yet understood and possibly involving the contractile properties of proteins, and' it is possible that this process continues to operate in the walls of the vacuoles or feeder canals. This secretory process may be the function of that part of the vacuolar apparatus which blackens on impregnation with osmic acid, and which seems to possess some degree of permanence from vacuole to vacuole and in some cases from parent to daughter cell. Remarkably little is known about the mechanism of systole. General body turgor may contribute, but it is not essential. In ciliates the main force is local and probably comes from a tension in the wall of the vacuole itself, but it is not known whether or not this is an active contraction of an oriented protein layer. The critical process for the initiation of systole is probably the opening of the pore. It is possible that in ciliates there is a rhythmically operating independent timing mechani,sm by which the vacuolar cycle is controlled, but its existence has not been demonstrated.

The Sourcebook for Teaching Science is a unique, comprehensive resource designed to give middle and high school science teachers a wealth of information that will enhance any science curriculum. Filled with innovative tools, dynamic activities, and practical lesson plans that are grounded in theory, research, and national standards, the book offers both new and experienced science teachers powerful strategies and original ideas that will enhance the teaching of physics, chemistry, biology, and the earth and space sciences.

The phylum Apicomplexa is characterized by the unique cell organisation of the zoites, the infective stages of unicellular parasites previously designated as Sporozoa. Apicomplexa includes Coccidian and Hematozoa well known for human and veterinary diseases they cause, such as malaria, toxoplasmosis, babesiosis, coccidiosis, and the large group of Gregarines, the early branching Apicomplexa. Gregarines are parasite of invertebrates and urochordates and they performed an extraordinary radiation from the marine and terrestrial hosts known from the Cambrian biodiversity explosion. After the basic publication in the Traité de Zoologie by Grassé in 1953, this second edition updates the knowledge with information provided by new technologies such as electron microscopy, biochemistry and molecular biology and to enlighten their high diversity of adaptation to invertebrate hosts living in a diversity of biotopes. The extracellular development of Gregarines, the considerable diversification of their cell cortex, their wide distribution in Annelids, Crustaceans, Echinoderms, Myriapods or Insects with about hundred thousands of species contribute to the understanding of many biological aspects of the pathogenic Apicomplexa. Since 1953, taxonomical reviews on Gregarines were published in the Illustrated Guide of Protozoa. In this supplement, there is a special emphasis on the hosts. Contributors include: Stuart Goldstein, Ryoko Kuriyama, Gérard Prensier, Jiri Vavra, Lawrence Howard Bannister, Jean François Dubremetz. Without the financial support of academic and non-profit organisations the edition of this volume would not have been possible. Many thanks to the LabEx BCDiv Biological and Cultural Diversities: Origins, Evolution, Interactions, Future, Groupement des Protistologues de Langue Francaise (GPLF), Société des Amis du Muséum, Société Française de Parasitologie for their generous grants.

Based on twenty years of research experience, this unique, large format volume presents an up-to-date treatment of the biology, relation to the host, taxonomy and diagnostic features of protozoan parasites infecting fishes. By presenting definitions of all 151 genera, keys for the determination of all main groups of fish protozoa, copious illustrations and half-tone plates, and details on the technique of investigation, the book makes it possible to determine all protozoan parasites of fishes down to generic level. In each genus, all important pathogenic species are dealt with, special attention being paid to their pathogenic action, and these are well documented by photomicrographs. A wide range of information is given on host-parasite relations, including data on pathogenicity of separate groups and species; and a host-parasite checklist enables a quick orientation on protozoa that may be encountered in one hundred economically important fish species. In addition to the to the true protozoan phyla, an appendix lists a few organisms of uncertain position with alleged or possible relation to protozoa; altogether, 561 species are described. This book is the first of its kind and should be invaluable reading for all fish parasitologists, fisheries biologists, aquaculturists and all others interested in protozoan parasites of fishes.

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