Download or read book Photoprocesses Photoreceptors and Evolution written by Jerome J. Wolken and published by Academic Press. This book was released on 2013-10-22 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photoprocesses, Photoreceptors, and Evolution discusses the important role that visible radiation has played in the development of photoreceptor systems, hence, in the evolution of life on earth. The book examines the spectrum of energies that impinge on the Earth, what kinds of molecules absorb these energies, and how they are structured within the cell to function as a photoreceptor system. The text describes the molecular structure of the cell membrane; the various kinds of pigment molecules; and the structures associated with photobiological phenomena. The relationship between the photoreceptor system and behavior, i.e. phototropism and phototaxis, photosynthesis, and vision, is also considered. The book further tackles the photoprocesses which function in photoperiodic phenomena - the “biological clocks , aging, memory, and bioluminescence. The text then demonstrates the structure of the invertebrate and vertebrate photoreceptors; and the intervebrate and vertebrate visual pigments and their photochemistry. Photobiologists will find the book invaluable.
Download or read book Photoreceptor Evolution and Function written by Martin Geoffrey Holmes and published by . This book was released on 1991 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: Summarizes current knowledge of the subject and discusses recent research into the parallel evolution of photoreceptors in bacteria, algae, fungi, higher plants, arthropods, fish, birds and mammals. It stresses the fundamental similarity between photoreceptor molecules in plants and animals.
Download or read book Light Detectors Photoreceptors and Imaging Systems in Nature written by Jerome J. Wolken and published by Oxford University Press. This book was released on 1995-02-23 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comparative survey of how animals detect light and image in their world includes discussions of photoreceptors, light emitters and optics. It focuses on the evolution of different types of optical systems, describing how these systems have developed into more complex designs.
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 Science & Business Media. This book was released on 2014-04-15 with total page 389 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 Evolution of Visual and Non visual Pigments written by David M. Hunt 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: Photopigments are molecules that react to light and mediate a number of processes and behaviours in animals. Visual pigments housed within the photoreceptors of the eye, such as the rods and cones in vertebrates are the best known, however, visual pigments are increasingly being found in other tissues, including other retinal cells, the skin and the brain. Other closely related molecules from the G protein family, such as melanopsin mediate light driven processes including circadian rhythmicity and pupil constriction. This Volume examines the enormous diversity of visual pigments and traces the evolution of these G protein coupled receptors in both invertebrates and vertebrates in the context of the visual and non-visual demands dictated by a species’ ecological niche.
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 Evolution and Molecular Mechanisms of Photoreceptor Transmutation in Reptiles written by Ryan K. Schott and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural light levels vary drastically, and to deal with this variance vertebrates typically utilize a duplex retina that contains rod photoreceptors for dim-light vision and cone photoreceptors for bright-light vision. Squamate reptiles, however, are unique in the predominance of simplex retinas that contain only rods or cones. Evolutionary transitions between rods and cones, termed photoreceptor transmutations, have been proposed to explain the evolution of these simplex retinas, but little previous work has focused on the molecular evolutionary underpinnings of the observed morphological changes. The goal of this thesis is to expand knowledge of the evolution and molecular mechanisms of photoreceptor transmutation. In the first study, I provide strong support for the hypothesis that the morphologically all-cone retina of diurnal colubrid snakes evolved through transmutation of the rods to resemble the appearance, and function, of cones. In the second, I developed a new method of targeted sequence capture that enables efficient sequencing of complete coding regions across divergent taxa, which further provided data for the final two studies. In the third, I analyzed the effect that photoreceptor transmutation and snake origins had on phototransduction gene evolution. I found results consistent with a strong effect of transmutation, including positive selection on cone-specific genes that may indicate adaptation during the evolution of rod-like cones. Furthermore, the low degree of gene loss in snakes, and a lack of relaxed selection early during their evolution, support a dim-light ancestor that lacked strong fossorial adaptations. In the final study, I used whole eye transcriptome sequencing to demonstrate that geckos do not utilize only cone phototransduction machinery as previously thought, and instead appear to co-express both rod and cone genes in cone photoreceptors. I also expand upon the third study to show that geckos experienced a similar shift in selective pressures as snakes that are also associated with transmutation. As a whole, this thesis provides the first molecular evidence for photoreceptor transmutation in snakes, produces a new methodology for efficiently producing sequence data relevant for molecular evolutionary studies, revises our view of transmutation in geckos, and provides the first evidence for molecular changes associated with photoreceptor transmutation.
Download or read book Natural Products of Woody Plants written by John W. Rowe and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 1275 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wood as found in trees and bushes was of primary importance to ancient humans in their struggle to control their environment. Subsequent evolution through the Bronze and Iron Ages up to our present technologically advanced society has hardly diminished the importance of wood. Today, its role as a source of paper products, furniture, building materials, and fuel is still of major significance. Wood consists of a mixture of polymers, often referred to as lignocellulose. The cellulose micro fibrils consist of an immensely strong, linear polymer of glucose. They are associated with smaller, more complex polymers composed of various sugars called hemicelluloses. These polysaccharides are embedded in an amorphous phenylpropane polymer, lignin, creating a remarkably strong com posite structure, the lignocellulosic cell wall. Wood also contains materials that are largely extraneous to this lignocellulosic cell wall. These extracellular substances can range from less than 1070 to about 35% of the dry weight of the wood, but the usual range is 2% -10%. Among these components are the mineral constituents, salts of calcium, potassium, sodium, and other metals, particularly those present in the soil where the tree is growing. Some of the extraneous components of wood are too insoluble to be ex tracted by inert solvents and remain to give extractive-free wood its color; very often these are high-molecular-weight polyphenolics.
Download or read book Liquid Crystals and Biological Structures written by Glenn Brown and published by Elsevier. This book was released on 2012-12-02 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid Crystals & Biological Structures covers analogies between biological structures and behavior of living cells to liquid crystalline structures and their behavior. It emphasizes that the physical state of the matter involved in life processes is to a great extent liquid crystalline. The first chapters discuss the physical, chemical, structural, and optical properties of liquid crystals, as well as the structure of the principal molecules associated with life systems. The core chapters cover selected cellular structures exhibiting liquid crystalline behavior to emphasize the nature of various cellular membranes, from the cell membranes to the receptors and effectors. The book also considers differentiated organelles of the cell that are specialized for photoreception, including chloroplasts for photosynthesis, the retinal photoreceptors of the eye, and the rods and cones for visual excitation. This book is suited for students and bioscientists who are interested in the potential of the liquid crystalline state in exploring a variety of biological phenomena.
Download or read book Photochemical and Photobiological Reviews written by Kendric C. Smith and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goals of the science of photobiology can be divided into four categories: to develop (I) ways to optimize the beneficial effects of light on man and his environment, (2) methods to protect organisms, including man, from the detrimental effects of light, (3) photochemical tools for use in studies of life processes, and (4) photochemical therapies in medicine. To achieve these goals will require the knowledgeable collaboration of biologists, chemists, engineers, mathematicians, physicians, and physicists; because photobiology is a truly multidisciplinary science. While a multidis ciplinary science is more intellectually demanding, it also has a greater potential for unexpected breakthroughs that can occur when data from several areas of science are integrated into new concepts for theoretical or practical use. Photochemical and Photobiological Reviews continues to provide in depth coverage of the many specialty areas of photobiology. It is hoped that these reviews will provide an important service to the younger scientists in the field and to senior scientists in related fields, because they provide a ready access to the recent literature in the field, and more importantly, they frequently offer a critical evaluation of the direction that the field is taking, or suggest a redirection when appropriate. Since it is important that this review series remain responsive to the needs of photochemists and photobiologists, the Editor would value com ments and suggestions from its readers.
Download or read book Current Catalog written by National Library of Medicine (U.S.) and published by . This book was released on with total page 1378 pages. Available in PDF, EPUB and Kindle. Book excerpt: First multi-year cumulation covers six years: 1965-70.
Download or read book Human and Machine Vision written by Virginio Cantoni and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: The following are the proceedings of the Third International Workshop on Perception held in Pavia, Italy, on September 27-30, 1993, under the auspices of four institutions: the Group of Cybernetic and Biophysics (GNCB)s of the National Research Council (CNR), the Italian Association for Artificial Intelligence (AI * IA), the Italian Association of Psychology (AlP), and the Italian Chapter of the International Association for Pattern Recognition (IAPR). The theme of this third workshop was: "Human and Machine Vision: Analogies and Divergencies." A wide spectrum of topics was covered, ranging from neurophysiology, to computer architecture, to psychology, to image understanding, etc. For this reason the structure of this workshop was quite different from those of the first two held in Parma (1991), and Trieste (1992). This time the workshop was composed of just eight modules, each one consisting of two invited lectures (dealing with vision in nature and machines, respectively) and a common panel discussion (including the two lecturers and three invited panellists).
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 0 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 Light Absorption in Sea Water written by Bogdian Wozniak and published by Springer Science & Business Media. This book was released on 2007-05-11 with total page 463 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a detailed description of light absorption and absorbents in seawaters with respect to provenance, region of the sea, depth of the occurrence and trophicity. The text is based on a substantial body of contemporary research results taken from the subject literature (over 400 references) and the work of the authors over a period of 30 years.
Download or read book Excited States in Organic Chemistry and Biochemistry written by Bernard Pullman and published by Springer Science & Business Media. This book was released on 1977-10-31 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the 10th Jerusalem Symposium on Quantum Chemistry and Biochemistry held in Jerusalem, Israel, March 28-31, 1977
Download or read book Physical Approaches to Biological Evolution written by Mikhail V. Volkenstein and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Mr. Wolkenstein's Physical Approaches to Biological Evolution, whether or not it proves to give the ultimate truth on the matters with which it deals, certainly deserves, by its breadth and scope and profundity, to be considered an impor tant event in the philosophical world." This is a quotation from an introduction written by Bertrand Russell for Ludwig Wittgenstein's Tractatus Logico-Philosophicus. I exchanged only name and subject. As for the rest, I could continue quoting Russell, but I would rather say something myself. As Wittgenstein did with formal logic, Wolkenstein rectifies our views on how to approach the logic of life from a formal theoretical basis. Many bio logists do not believe that their subject lends itself to the scrutiny of physical theory. They certainly admit that one can simulate biological phenomena by models that can be expressed in a mathematical form. However, they do not believe that biology can be given a theoretical foundation that is defined within the general framework of physics. Rather, they insist on a holistic approach, banning any reduction to fundamental principles subject to physical theory.
