Download or read book Sensitivity and Adaptation in Vertebrate Photoreceptors Evolution and Mechanism written by Ala Morshedian and published by . This book was released on 2016 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lamprey are cyclostomes, which diverged from jawed vertebrates (fishes, amphibians, mammals) in the Cambrian perhaps 500 Mya. Using single-cell measurements with suction recording from the photoreceptors of adulti Petromyzon marinusi we first show that this primitive vertebrate has a duplex retina: rods respond to single photons, have a longer integration time, and are 80 times more sensitive than cones, much as in other vertebrates. We then demonstrate that responses to maintained steps of light decay as in other vertebrates and flash responses superimposed on steady backgrounds show decreases in sensitivity and changes in waveform in both rods and cones, also typical of other vertebrates. Backgrounds produce a decrease in maximum flash-response amplitude and an increase in the flash intensity necessary to produce a detectable response, with characteristic shifts of response-intensity curves along the intensity axis. Increasing background light had little effect on response onset but monotonically increased the rate of response decay. Sensitivity as a function of background intensity decreased by Weber's Law in both rods and cones; rods show incremental saturation, and cones begin to adapt near the intensity at which rod saturation occurs. Bright bleaching light produces an equivalent background, with opsin in rods 7.5 x 10-6i times as effective in stimulating the cascade as Rh* (2 x 10-5i in mouse rods). The decreases in sensitivity and acceleration of response decay in stably bleached photoreceptors can be nearly completely reversed with exogenous 11-cisi retinal. We then used mice to demonstrate that in wild-type animals background lights decrease the sensitivity of the rod and accelerate the kinetics of the response, and these processes occur rapidly within 250ms after presentation of the background. We also recorded the dark current from recoverin-knockout photoreceptors and did not detect any changes in flash sensitivity. However, responses to steps of light were significantly desensitized and the rate of reduction in sensitivity is much faster when recoverin is eliminated compared to wild-type rods. The waveform of the response however, appears to be independent of the background intensity in recoverin-knock out animals.
Download or read book Comparative Physiology and Evolution of Vision in Invertebrates written by H. Autrum and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the comparative physiology of photoreception by the Protista and the invertebrates two aspects are emphasized: (1) the diversity of visual processes in these groups and (2) their bearing upon general mechanisms of photoreception. Invertebrates have evolved a far greater variety of adaptations than vertebrates modifications aiding survival in the remarkably different biotopes they occupy. The number of species in itself suggests this multiformity; each of them has peculiarities of its own, in morphology as well as in physiology and behavior. But these special adaptations are variations on a few great themes. Although the catalogue of invertebrate species is immense, the literature concerning them nearly rivals it in extent-even if one considers only that fraction dealing with visual physiology. Taxonomy proceeds by grouping the species, categorizing them in genera, families, orders, and progressively larger units. Similarly, comparative physiology aims at an analogous, more or less compre hensive, classification. This Part A of Volume VII/6, like Part B that follows it, emphasizes the broad questions that concern groups larger than the individual species; in some cases these questions have general applicability. The middle course between approaches that are too specialized and those that are too general is often elusive, but here we attempt to follow it. The vast number of special adaptations-probably, as we have said, as large as the number of species-is beyond the range even of a handbook.
Download or read book Vertebrate Photoreceptors written by Takahisa Furukawa and published by Springer. This book was released on 2016-08-23 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a series of comprehensive views on various important aspects of vertebrate photoreceptors. The vertebrate retina is a tissue that provides unique experimental advantages to neuroscientists. Photoreceptor neurons are abundant in this tissue and they are readily identifiable and easily isolated. These features make them an outstanding model for studying neuronal mechanisms of signal transduction, adaptation, synaptic transmission, development, differentiation, diseases and regeneration. Thanks to recent advances in genetic analysis, it also is possible to link biochemical and physiological investigations to understand the molecular mechanisms of vertebrate photoreceptors within a functioning retina in a living animal. Photoreceptors are the most deeply studied sensory receptor cells, but readers will find that many important questions remain. We still do not know how photoreceptors, visual pigments and their signaling pathways evolved, how they were generated and how they are maintained. This book will make clear what is known and what is not known. The chapters are selected from fields of studies that have contributed to a broad understanding of the birth, development, structure, function and death of photoreceptor neurons. The underlying common word in all of the chapters that is used to describe these mechanisms is “molecule”. Only with this word can we understand how these highly specific neurons function and survive. It is challenging for even the foremost researchers to cover all aspects of the subject. Understanding photoreceptors from several different points of view that share a molecular perspective will provide readers with a useful interdisciplinary perspective.
Download or read book Webvision written by Helga Kolb and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Visual System in Vertebrates written by F. Crescitelli and published by Springer Science & Business Media. This book was released on 2013-12-11 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt: The vertebrate eye has been, and continues to be, an object of interest and of inquiry for biologists, physicists, chemists, psychologists, and others. Quite apart from its important role in the development of ophthalmology and related medical disciplines, the vertebrate eye is an exemplar of the ingenuity of living systems in adapting to the diverse and changing environments in which vertebrates have evolved. The wonder is not so much that the visual system, like other body systems, has been able to adapt in this way, but rather that these adaptations have taken such a variety of forms. In a previous volume in this series (VII/I) Eakin expressed admiration for the diversity of invertebrate photoreceptors. A comparable situation exists for the vertebrate eye as a whole and one object of this volume is to present to the reader the nature of this diversity. One result of this diversification of ocular structures and properties is that the experimental biologist has available a number of systems for study that are unique or especially favorable for the investigation of particular questions in visual science or neurobiology. This volume includes some examples of progress made by the use of such specially selected vertebrate systems. It is our hope that this comparative approach will continue to reveal new and useful preparations for the examination of important questions.
Download or read book Visual Ecology written by Thomas W. Cronin and published by Princeton University Press. This book was released on 2014-08-10 with total page 427 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive treatment of visual ecology Visual ecology is the study of how animals use visual systems to meet their ecological needs, how these systems have evolved, and how they are specialized for particular visual tasks. Visual Ecology provides the first up-to-date synthesis of the field to appear in more than three decades. Featuring some 225 illustrations, including more than 140 in color, spread throughout the text, this comprehensive and accessible book begins by discussing the basic properties of light and the optical environment. It then looks at how photoreceptors intercept light and convert it to usable biological signals, how the pigments and cells of vision vary among animals, and how the properties of these components affect a given receptor's sensitivity to light. The book goes on to examine how eyes and photoreceptors become specialized for an array of visual tasks, such as navigation, evading prey, mate choice, and communication. A timely and much-needed resource for students and researchers alike, Visual Ecology also includes a glossary and a wealth of examples drawn from the full diversity of visual systems. The most up-to-date overview of visual ecology available Features some 225 illustrations, including more than 140 in color, spread throughout the text Guides readers from the basic physics of light to the role of visual systems in animal behavior Includes a glossary and a wealth of real-world examples
Download or read book The Biology of Hagfishes written by Jørgen Mørup Jørgensen and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 577 pages. Available in PDF, EPUB and Kindle. Book excerpt: The hagfishes comprise a uniform group of some 60 species inhabiting the cool or deep parts of the oceans of both hemispheres. They are considered the most primitive representatives of the group of craniate chordates, which - apart from the hagfishes that show no traces of verte brae -includes all vertebrate animals. Consequently the hagfishes have played and still playa central role in discussions concerning the evolution of the vertebrates. Although most of the focus on hagfishes may be the result of their being primitive, it should not be forgotten that, at the same time, they are specialized animals with a unique way of life that is interesting in its own right. It is now more than 30 years since a comprehensive treatise on hagfishes was published. The Biology of Myxine, edited by Alf Brodal and Ragnar Fange (Universitetsforlaget, Oslo, 1963), provided a wealth of information on the biology of hagfishes, and over the years remained a major source of information and inspiration to students of hagfishes.
Download or read book The Vertebrate Eye and Its Adaptive Radiation written by Gordon L. Walls and published by Alpha Edition. This book was released on 2020-04 with total page 806 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book has been considered by academicians and scholars of great significance and value to literature. This forms a part of the knowledge base for future generations. So that the book is never forgotten we have represented this book in a print format as the same form as it was originally first published. Hence any marks or annotations seen are left intentionally to preserve its true nature.
Download or read book Evolution of the Vertebrate Auditory System written by Geoffrey A. Manley and published by Springer Science & Business Media. This book was released on 2013-12-01 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: The function of vertebrate hearing is served by a surprising variety of sensory structures in the different groups of fish, amphibians, reptiles, birds, and mammals. This book discusses the origin, specialization, and functional properties of sensory hair cells, beginning with environmental constraints on acoustic systems and addressing in detail the evolutionary history behind modern structure and function in the vertebrate ear. Taking a comparative approach, chapters are devoted to each of the vertebrate groups, outlining the transition to land existence and the further parallel and independent adaptations of amniotic groups living in air. The volume explores in depth the specific properties of hair cells that allowed them to become sensitive to sound and capable of analyzing sounds into their respective frequency components. Evolution of the Vertebrate Auditory System is directed to a broad audience of biologists and clinicians, from the level of advanced undergraduate students to professionals interested in learning more about the evolution, structure, and function of the ear.
Download or read book Comparative Physiology and Evolution of Vision in Invertebrates written by Hansjochem Autrum and published by . This book was released on 1979 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Senses of Fish written by Gerhard von der Emde and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 393 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fish comprise more than 50% of all living vertebrates and are found in a wide range of highly diverse habitats like the deep sea, the shoreline, tide pools, tropical streams and sweetwater ponds. During evolution, the senses of fish have adapted to the physical conditions of the environment in which different species live. As a result, the senses of fish exhibit a remarkable diversity that allows different species to deal with the physical constraints imposed by their habitat. In addition, fish have evolved several `new' sensory systems that are unique to the aquatic environment. In this book, examples of adaptation and refinement are given for six sensory systems: The visual system, The auditory system, The olfactory system, The mechanosensory lateral line system, The taste system, The electrosensory system. In each case, the environmental conditions under which a particular group of fish lives are analyzed. This is followed by a description of morphology and physiology of the sensory system and by an evaluation of its perceptional capabilities. Finally, the sensory adaptations to the particular conditions that prevail in the habitat of a species are highlighted. The various examples from different groups of fish presented in this book demonstrate the impressive capability of fish sensory systems to effectively overcome physical problems imposed by the environment.
Download or read book Sensory Evolution on the Threshold written by J. G. M. Thewissen and published by Univ of California Press. This book was released on 2008-02-04 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ranging from crocodiles and penguins to seals and whales, this synthesis explores the function and evolution of sensory systems in animals whose ancestors lived on land. It explores the dramatic transformation of smell, taste, sight, hearing, and balance that occurred as lineages of reptiles, birds, and mammals returned to aquatic environments.
Download or read book Evolution s Witness written by Ivan R. Schwab and published by Oxford University Press. This book was released on 2012-01-05 with total page 323 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The evolution of the eye spans 3.75 billion years from single cell organisms with eyespots to Metazoa with superb camera style eyes. At least ten different ocular models have evolved independently into myriad optical and physiological masterpieces. The story of the eye reveals evolution's greatest triumph and sweetest gift. This book describes its journey"--Provided by publisher.
Download or read book Primate Origins Adaptations and Evolution written by Matthew J. Ravosa and published by Springer Science & Business Media. This book was released on 2007-01-05 with total page 846 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a novel focus on adaptive explanations for cranial and postcranial features and functional complexes, socioecological systems, life history patterns, etc. in early primates. It further offers a detailed rendering of the phylogenetic affinities of such basal taxa to later primate clades as well as to other early/recent mammalian orders. In addition to the strictly paleontological or systemic questions regarding Primate Origins, the editors concentrate on the adaptive significance of primate characteristics. Thus, the book provides the broadest possible perspective on early primate phylogeny and the adaptive uniqueness of the Order Primates.
Download or read book Physiology of Photoreceptor Organs written by M. G. F. Fuortes and published by . This book was released on 1972 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Animal Eyes written by Michael F. Land and published by OUP Oxford. This book was released on 2012-03-01 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Animal Eyes provides a comparative account of all known types of eye in the animal kingdom, outlining their structure and function with an emphasis on the nature of the optical systems and the physical principles involved in image formation. A universal theme throughout the book is the evolution and taxonomic distribution of each type of eye, and the roles of different eye types in the behaviour and ecology of the animals that possess them. In comparing the specific capabilities of eyes, it considers the factors that lead to good resolution of detail and the ability to function under a wide range of light conditions. This new edition is fully updated throughout, incorporating more than a decade of new discoveries and research.
Download or read book The Visual System of Fish written by Ron Douglas and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 531 pages. Available in PDF, EPUB and Kindle. Book excerpt: A question often asked of those of us who work in the seemingly esoteric field of fish vision is, why? To some of us the answer seems obvious - how many other visual scientists get to dive in a tropical lagoon in the name of science and then are able to eat their subjects for dinner? However, there are better, or at least scientifically more acceptable, reasons for working on the visual system of fish. First, in terms of numbers, fish are by far the most important of all vertebrate classes, probably accounting for over half (c. 22 000 species) of all recognized vertebrate species (Nelson, 1984). Furthermore, many of these are of commercial importance. Secondly, if one of the research aims is to understand the human visual system, animals such as fish can tell us a great deal, since in many ways their visual systems, and specifically their eyes, are similar to our own. This is fortunate, since there are several techniques, such as intracellular retinal recording, which are vital to our understanding of the visual process, that cannot be performed routinely on primates. The cold blooded fish, on the other hand, is an ideal subject for such studies and much of what we know about, for example, the fundamentals of information processing in the retina is based on work carried out on fish (e. g. Svaetichin, 1953).
