Studies on Osmoregulation and Endocrine Control of Osmoregulation in the Atlantic Stingray, Dasyatis Sabina


Book Description

Osmoregulation and endocrine control of osmoregulation were studied in the euryhaline stingray, Dasyatis sabina. In hypersaline sea water (above 35ppt), the ability to regulate plasma solutes was reduced relative to regulation in the optimum, hyposaline (12-28ppt) range. Survival in high salinities was dependent on slow acclimation, while rapid change to low salinities was tolerated. These results appear consistent with adaptations necessary for salinity changes occurring in a bay environment. Natural, uninduced rectal gland secretion was obtained in D. sabina. The average chloride concentration of the rectal gland fluid was 583.3 m-moles/1. The average flow rate was 0.13 ml/kg/hr. Occurrence and amount of rectal gland secretion were erratic. Thyroidectomy, in sea water of 23ppt salinity, caused a significant rise in plasma urea concentrations in D. sabina. Replacement injections of thyroxine lowered plasma urea levels in thyroidectomized animals. Removal of the rostal pars distalis caused plasma urea to increase. Replacement injections of prolactin lowered plasma urea levels, as did replacement ACTH injections. Replacement of both prolactin and ACTH caused variable results concerning urea. Problems of dosage, stress, and possible seasonal influences, most likely affected the results of the endocrine study










Fish Osmoregulation


Book Description

Fish lives in environments with a wide variety of chemical characteristics (fresh, brackish and seawater, acidic, alkaline, soft and hard waters). From an osmoregulatory point of view, fish have developed several mechanisms to live in these different environments. Fish osmoregulation has always attracted considerable attention and in the last years several studies have increased our knowledge of this physiological process. In this book several specialists have analyzed and reviewed the new data published regarding fish osmoregulation. The chapters present an integrative synthesis of the different aspects of this field focusing on osmoregulation in specific environments or situations, function of osmoregulatory organs, general mechanisms and endocrine control. In addition, interactions of osmoregulatory mechanisms with the immune system, diet and metabolism were also reviewed. New emerging techniques to study osmoregulation has also been analysed.







Fish Physiology: Euryhaline Fishes


Book Description

The need for ion and water homeostasis is common to all life. For fish, ion and water homeostasis is an especially important challenge because they live in direct contact with water and because of the large variation in the salt content of natural waters (varying by over 5 orders of magnitude). Most fish are stenohaline and are unable to move between freshwater and seawater. Remarkably, some fishes are capable of life in both freshwater and seawater. These euryhaline fishes constitute an estimated 3 to 5% of all fish species. Euryhaline fishes represent some of the most iconic and interesting of all fish species, from salmon and sturgeon that make epic migrations to intertidal mudskippers that contend with daily salinity changes. With the advent of global climate change and increasing sea levels, understanding the environmental physiology of euryhaline species is critical for environmental management and any mitigative measures. This volume will provide the first integrative review of euryhalinity in fish. There is no other book that focuses on fish that have the capacity to move between freshwater and seawater. The different challenges of salt and water balance in different habitats have led to different physiological controls and regulation, which heretofore has not been reviewed in a single volume. Collects and synthesizes the literature covering the state of knowledge of the physiology of euryhaline fish Provides the foundational information needed for researchers from a variety of fields, including fish physiology, conservation and evolutionary biology, genomics, ecology, ecotoxicology, and comparative physiology All authors are the leading researchers and emerging leaders in their fields




Osmotic and Ionic Regulation


Book Description

In the 40 years since the classic review of osmotic and ionic regulation written by Potts and Parry, there has been astonishing growth in scientific productivity, a marked shift in the direction and taxonomic distribution of research, and amazing changes in the technology of scientific research" It is indicative of the growth of the subject that as




The Central Nervous System of Vertebrates


Book Description

This comprehensive reference is clearly destined to become the definitive anatomical basis for all molecular neuroscience research. The three volumes provide a complete overview and comparison of the structural organisation of all vertebrate groups, ranging from amphioxus and lamprey through fishes, amphibians and birds to mammals. This thus allows a systematic treatment of the concepts and methodology found in modern comparative neuroscience. Neuroscientists, comparative morphologists and anatomists will all benefit from: * 1,200 detailed and standardised neuroanatomical drawings * the illustrations were painstakingly hand-drawn by a team of graphic designers, specially commissioned by the authors, over a period of 25 years * functional correlations of vertebrate brains * concepts and methodology of modern comparative neuroscience * five full-colour posters giving an overview of the central nervous system of the vertebrates, ideal for mounting and display This monumental work is, and will remain, unique; the only source of such brilliant illustrations at both the macroscopic and microscopic levels.




Urea Transporters


Book Description

The mechanisms and physiological functions of urea transporters across biological membranes are subjects of long-standing interests. Although urea represents roughly 40% of all urinary solutes in normal human urine, the handling of urea in the tissues has been largely neglected in the past and few clinical or experimental studies now report data on urea. Most recent physiological text books include chapters on water and electrolyte physiology but no chapter on urea. Our aim in writing this book is to stimulate further research in new directions by providing novel and provocative insights into the further mechanisms and physiological significance of urea metabolism and transport in mammals. This book offers a state-of-the-art report on recent discoveries concerning urea transport and where the field is going. It mainly focuses on advances made over the past 20 years on the biophysics, genetics, protein structure, molecular biology, physiology, pathophysiology and pharmacology of urea transport in mammalian cell membranes. It will help graduate students and researchers to get an overall picture of mammalian urea transporters and may also yield benefits for pharmaceutical companies with regard to drug discovery based on the urea transporter. Baoxue Yang is a professor and vice chairman of the Department of Pharmacology, Peking University. He is also an adjunct professor of Jilin University and a visiting professor of Northeast Normal University. Prof. Yang has been researching urea transporters for nearly 20 years and has published more than 70 original research articles in this field.




The Histology of Fishes


Book Description

The book is a multi-authored book of 18 chapters comprising the state of the art work of all relevant topics on modern fish histology from 28 authors from ten countries. The topics include Introduction to Histological Techniques, Integument, Fish Skeletal Tissues, Muscular System, Structure and Function of Electric Organs, Digestive System, Glands of the Digestive Tract, Swim Bladder, Kidney, Ovaries and Eggs, Egg Envelopes, Testis Structure, Spermatogenesis, and Spermatozoa in Teleost Fishes, Cardiovascular System and Blood, Immune System of Fish, Gills: Respiration and Ionic-Osmoregulation, Sensory Organs, Morphology and Ecomorphology of the Fish Brain, and Endocrine System. Structural and functional aspects are treated and in a comparative way fish diversity at various taxonomic levels is integrated.