Download or read book The Effect of Propylthiouracil on the Oxygen Consumption and Radioiodine Metabolism of the Frog Rana Pipiens in Winter written by Herman Matthew Meisner and published by . This book was released on 1961 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study was undertaken to evaluate the physiological importance of the thyroid gland in the adult frog, Rana pipiens , in winter. Male frogs, weighing between 40-55 grams, were kept in running water and fed liver once a week. The thyroid gland was chemically inhibited by oral administration of 1.5 mg. of propylthiouracil three times a week. Oxygen consumption was measured weekly from December 21 to February 23 with volumetric respirometers at a temperature of 16+0.1°C. There were never any significant differences between the metabolic rates of the propylthiouracil inhibited frogs and the controls over the entire experimental period. Propylthiouracil effectively blocked the thyroid radioiodine uptake and blood conversion ratio, but after nine weeks, thyroid iodine stores were only reduced by one-half. This low secretion rate together with the fact that propylthiouracil did not alter metabolic rate suggests that the frog thyroid is of no calorigenic importance during the winter. The seasonal thyroid activity pattern was found to be characterized by a regression in the iodine concentrating capacity of the thyroid gland and blood from August to December, and reactivation towards the end of February. The appearance of monoiodotyrosine and diiodotyrosine in the circulation of Rana pipienS indicates that thyroidal deiodinase is unable to reduce iodotyrosines to iodide. It is postulated that there is an association between the presence of iodotyrosines in the circulation and the reduced thyroid function of poikilotherms.
Download or read book Boron written by C. Smallwood and published by . This book was released on 1998 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book evaluates the risks to human health and the environment posed by boron, a naturally occurring element widely distributed in the form of various inorganic borates in the oceans, sedimentary, rocks, coal, shale and some soils. Boron is also used in laundry bleach and in the manufacture of glass, glass products, fertilizers and herbicides, antiseptics, and pharmaceuticals. Since boron is widely detected in drinking-water and occurs naturally in fruits, nuts, and vegetables, the report gives particular attention to health risks associated with exposure of the general population through diet and drinking-water.A section on sources of human and environmental exposure cites evidence that boron enters the environment mainly through volatilization from seawater, volcanoes, geothermal steam, and natural weathering of clay-rich sedimentary rock. Although industrial uses account for much smaller releases, the report notes that all of the boron from the sodium perborate contained in detergents ultimately enters the wastewater system, and is not removed by standard water treatment procedures.
Download or read book Mechanisms of Life History Evolution written by Thomas Flatt and published by OUP Oxford. This book was released on 2011-05-12 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: Life history theory seeks to explain the evolution of the major features of life cycles by analyzing the ecological factors that shape age-specific schedules of growth, reproduction, and survival and by investigating the trade-offs that constrain the evolution of these traits. Although life history theory has made enormous progress in explaining the diversity of life history strategies among species, it traditionally ignores the underlying proximate mechanisms. This novel book argues that many fundamental problems in life history evolution, including the nature of trade-offs, can only be fully resolved if we begin to integrate information on developmental, physiological, and genetic mechanisms into the classical life history framework. Each chapter is written by an established or up-and-coming leader in their respective field; they not only represent the state of the art but also offer fresh perspectives for future research. The text is divided into 7 sections that cover basic concepts (Part 1), the mechanisms that affect different parts of the life cycle (growth, development, and maturation; reproduction; and aging and somatic maintenance) (Parts 2-4), life history plasticity (Part 5), life history integration and trade-offs (Part 6), and concludes with a synthesis chapter written by a prominent leader in the field and an editorial postscript (Part 7).
Download or read book Lampreys Biology Conservation and Control written by Margaret F. Docker and published by Springer. This book was released on 2014-11-24 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides the most comprehensive review of lamprey biology since Hardisty and Potter’s five-volume “The Biology of Lampreys” published more than 30 years ago. Published in two volumes, it includes contributions from international lamprey experts, reviewing and providing new insights into the evolution, general biology, and management of lampreys worldwide. This first volume offers up-to-date chapters on the systematics, general biology, conservation status, and conservation needs of lampreys. It will serve as an important reference for researchers working on any aspect of lamprey biology and fishery managers whose mandate is to control or conserve lamprey populations.
Download or read book Hormonally Active Agents in the Environment written by National Research Council and published by National Academies Press. This book was released on 2000-02-03 with total page 453 pages. Available in PDF, EPUB and Kindle. Book excerpt: Some investigators have hypothesized that estrogens and other hormonally active agents found in the environment might be involved in breast cancer increases and sperm count declines in humans as well as deformities and reproductive problems seen in wildlife. This book looks in detail at the science behind the ominous prospect of "estrogen mimics" threatening health and well-being, from the level of ecosystems and populations to individual people and animals. The committee identifies research needs and offers specific recommendations to decision-makers. This authoritative volume: Critically evaluates the literature on hormonally active agents in the environment and identifies known and suspected toxicologic mechanisms and effects of fish, wildlife, and humans. Examines whether and how exposure to hormonally active agents occursâ€"in diet, in pharmaceuticals, from industrial releases into the environmentâ€"and why the debate centers on estrogens. Identifies significant uncertainties, limitations of knowledge, and weaknesses in the scientific literature. The book presents a wealth of information and investigates a wide range of examples across the spectrum of life that might be related to these agents.
Download or read book Natural Products in the Chemical Industry written by Bernd Schaefer and published by Springer. This book was released on 2015-05-26 with total page 844 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural Products in the Chemical Industry is not a conventional textbook, but rather an invitation to join an entertaining journey that takes you into the fascinating world of natural products. This book features diverse compound classes from a number of areas: colourants, fragrances and flavourings, amino acids, pharmaceuticals, hormones, vitamins and agrochemicals. Whether you are a teacher or a scholar, an undergraduate or graduate student, a professional chemist in industry or academia, or someone just interested in natural sciences, this book allows you to be inspired and entertained by facts and information along with enjoyable anecdotes, historical, economic, political, biological and social considerations. Experts in the field can have a pleasurable time cruising through captivating synthesis methods, which enable the generation of complex molecules on industrial scale. This book · deals with the manufacturing of larger quantities of complex molecules (asymmetric and heterocyclic compounds, polycyclic structures, macrocycles and small rings) · displays all reaction schemes in colour, which makes them easy to read · highlights aesthetics and elegance in modern industrial organic chemistry
Download or read book Comparative Physiology of the Vertebrate Kidney written by William H. Dantzler and published by Springer. This book was released on 2016-07-05 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: This second edition offers a comprehensive overview of the physiological functions of vertebrate kidneys from a comparative viewpoint, with particular emphasis on nonmammalian vertebrates. The topics covered include renal structure; glomerular ultrafiltration; tubular transport of inorganic ions, organic substances, and fluid; and urine dilution and concentration. Mammalian renal function is only considered for purposes of comparison with nonmammalian renal function and as a frame of reference for some of the discussions. The major findings on nonmammalian renal function and the important unanswered questions raised by those findings are described in detail. As such, the book provides comprehensive information on comparative renal function for biological scientists and advanced students of biology with some knowledge of physiology and a desire to know more about renal function in vertebrates, and for mammalian renal physiologists who wish to obtain a broader view of renal function.
Download or read book OECD Guidelines for the Testing of Chemicals Section 2 Test No 231 Amphibian Metamorphosis Assay written by OECD and published by OECD Publishing. This book was released on 2009-09-08 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Test Guideline describes an amphibian metamorphosis assay intended to screen substances which may interfere with the normal functioning of the hypothalamo-pituitary-thyroid axis. The assay was validated with the species Xenopus laevis, which is ...
Download or read book Methods in Reproductive Aquaculture written by Elsa Cabrita and published by CRC Press. This book was released on 2008-08-22 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt: The large amount of information on fish reproduction available is not always readily accessible to all interested parties. Written to appeal to aquaculturalists, conservation managers, and scientific researchers, Methods in Reproductive Aquaculture provides an overview of available techniques and addresses ways to improve depleted stocks of endange
Download or read book Human Physiology written by C. Chatterjee and published by . This book was released on 1987-01-01 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Controlled Release Biochemical Effects of Pesticides Inhibition of Plant Pathogenic Fungi written by and published by Springer. This book was released on 2012-03-23 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the middle of the Sixties, new types of formulation for biologically active com pounds have been developed, which have been introduced into the literature under the term Controlled Release Formulations (CRF). Stimulated by results from former and successful pharmaceutical research, which was engaged in the production of prepa rations with protracted effects (introduction onto the market in the year 1952 of D amphetamine in the form of pellets, coated to varying degrees with fats and waxes) 1), experiments were carried out to transfer the prolongation of effectiveness to pesticidal substances also, by means of a depot formulation. Initial work was concerned with the production of protective coatings for sonar systems in marine ecosystems. By means of antifouling paints or rubber coatings containing tri-n-butyl-tin oxide (TBTO), the growth of marine organisms on sonar domes, buoys and hulls in the water could be effectively prevented 2. 3). Controlled release formUlations of pesticides are defined as depot systems which continuously release their toxic constituents into the environment over a specified period of time (usually months to years) 4). According to this definition, such formu lations can be successfully employed where a chronic exposure to biologically active compounds is required over a longer period. The following hypothetical example is intended to illustrate this 5). In Fig. 1, the duration of activity of a non-persistent pesticide with a loss rate under environmental conditions of t1/2 = 15 days, is graphically illustrated.
Download or read book Mechanical Design in Organisms written by Stephen A. Wainwright and published by Princeton University Press. This book was released on 1982-07-21 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with an interface between mechanical engineering and biology. It reviews biological structural materials and systems and their mechanically important features and demonstrates that function at any particular level of biological integration is permitted and controlled by structure at lower levels of integration.
Download or read book Endocrinology written by Samuel McDonald McCann and published by Oxford University Press, USA. This book was released on 1988 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work are thematic historical essays written by pioneers in the field and edited by the author.
Download or read book Methods in Hormone Research Bioassay written by Ralph Isadore Dorfman and published by . This book was released on 1962 with total page 802 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Endocrines and Osmoregulation written by P.J. Bentley and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: From a review of the previous edition: "I strongly recommend it as an essential reading and reference book for younger and older workers alike". Nature
Download or read book The Adrenocortical Hormones Their Origin Chemistry Physiology and Pharmacology written by Helen Wendler Deane and published by . This book was released on 1962 with total page 780 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Origin of Chordates written by Q. Bone and published by . This book was released on 1979 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
