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Author: Camille Curantz Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Natural patterns constitute one of the most diverse features observed in wild animals. The development of such patterns requires a series of morphogenetic events involving a differential response of a naïve tissue to chemical and mechanical positional cues. To what extent these processes contribute to the shape of the natural variation remains unclear. In birds, feather primordia are implanted in typical geometries which vary between birds in primordia size, spacing and pattern regularity. It has been shown that the development of the feather array surely involves self-organising processes. Such processes rely on molecular and cellular factors that cumulate and cooperate temporally and spatially in the developing skin. We showed that the patterning of feather primordia involves prior regionalisation of the skin into competent domains forming a specie-specific pre-pattern that influences the resulting pattern. The comparative description of the local variation of the feather array in these birds according to their initial competent domains shows that variation in the amplitude of dermal cell anisotropy correlates with variation in pattern regularity. Using ex vivo perturbations of skin architecture by an inhibitor of actin filament polymerisation, I showed that the anisotropy of dermal cells prior to feather primordia formation can be seen a readout of the competent state of the tissue to form a regular pattern. These results provide insights into the cellular basis of self-organisation and demonstrate that tissue morphology, constrain the cell response to the positional cues and contribute to shape the variation of the geometry of the feather array observed in nature.
Author: Camille Curantz Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Natural patterns constitute one of the most diverse features observed in wild animals. The development of such patterns requires a series of morphogenetic events involving a differential response of a naïve tissue to chemical and mechanical positional cues. To what extent these processes contribute to the shape of the natural variation remains unclear. In birds, feather primordia are implanted in typical geometries which vary between birds in primordia size, spacing and pattern regularity. It has been shown that the development of the feather array surely involves self-organising processes. Such processes rely on molecular and cellular factors that cumulate and cooperate temporally and spatially in the developing skin. We showed that the patterning of feather primordia involves prior regionalisation of the skin into competent domains forming a specie-specific pre-pattern that influences the resulting pattern. The comparative description of the local variation of the feather array in these birds according to their initial competent domains shows that variation in the amplitude of dermal cell anisotropy correlates with variation in pattern regularity. Using ex vivo perturbations of skin architecture by an inhibitor of actin filament polymerisation, I showed that the anisotropy of dermal cells prior to feather primordia formation can be seen a readout of the competent state of the tissue to form a regular pattern. These results provide insights into the cellular basis of self-organisation and demonstrate that tissue morphology, constrain the cell response to the positional cues and contribute to shape the variation of the geometry of the feather array observed in nature.
Author: Antonio Lima-de-Faria Publisher: Springer Science & Business Media ISBN: 3642253016 Category : Science Languages : en Pages : 171
Book Description
After having read this book you will never see birds in the same way again. The unexpected patterns displayed by a bird’s body have been seen as bizarre events that demanded little attention or were described as ‘amazing curiosities’. None of these surprising features seem to be fortuitous. They appear to be an integral part of a rigid order and a coherent geometry, which is directed by simple gene interactions and molecular cascades occurring at various cellular levels, and at different times, during the organism’s development. A novel geometry unfolds in front of your eyes, giving the body configurations another meaning. Lima-de-Faria is Professor Emeritus of Molecular Cytogenetics at Lund University, Lund, Sweden. This is his sixth book dealing with the molecular organization of the chromosome and its implications for the understanding of the mechanisms responsible for biological evolution.
Author: Antonio Lima-de-Faria Publisher: Springer ISBN: 3319060562 Category : Science Languages : en Pages : 188
Book Description
New concepts arise in science when apparently unrelated fields of knowledge are put together in a coherent way. The recent results in molecular biology allow to explain the emergence of body patterns in animals that before could not be understood by zoologists. There are no ”fancy curiosities” in nature. Every pattern is a product of a molecular cascade originating in genes and a living organism arises from the collaboration of these genes with the outer physical environment. Tropical fishes are as startling in their colors and geometric circles as peacocks. Tortoises are covered with the most regular triangles, squares and concentric circles that can be green, brown or yellow. Parallel scarlet bands are placed side by side of black ones along the body of snakes. Zebras and giraffes have patterns which are lessons in geometry, with their transversal and longitudinal stripes, their circles and other geometric figures. Monkeys, like the mandrills, have a spectacularly colored face scarlet nose with blue parallel flanges and yellow beard. All this geometry turns out to be highly molecular. The genes are many and have been DNA sequenced. Besides they not only deal with the coloration of the body but with the development of the brain and the embryonic process. A precise scenario of molecular events unravels in the vertebrates. It may seem far-fetched, but the search for the origin of this geometry made it mandatory to study the evolution of matter and the origin of the brain. It turned out that matter from its onset is pervaded by geometry and that the brain is also a prisoner of this ordered construction. Moreover, the brain is capable of altering the body geometry and the geometry of the environment changes the brain. Nothing spectacular occurred when the brain arrived in evolution. Not only it came after the eye, which had already established itself long ago, but it had a modest origin. It started from sensory cells on the skin that later aggregated into clusters of neurons that formed ganglia. It also became evident that pigment cells, that decide the establishment of the body pattern, originate from the same cell population as neurons (the neural crest cells). This is a most revealing result because it throws light on the power that the brain has to rapidly redirect the coloration of the body and to change its pattern. Recent experiments demonstrate how the brain changes the body geometry at will and within seconds, an event that could be hardly conceived earlier. Moreover, this change is not accidental it is related to the surrounding environment and is also used as a mating strategy. Chameleons know how to do it as well as flat fishes and octopuses. No one would have dared to think that the brain had its own geometry. How could the external geometry of solids or other figures of our environment be apprehended by neurons if these had no architecture of their own? Astonishing was that the so called ”simple cells”, in the neurons of the primary visual cortex, responded to a bar of light with an axis of orientation that corresponded to the axis of the cell’s receptive field. We tend to consider our brain a reliable organ. But how reliable is it? From the beginning the brain is obliged to transform reality. Brain imagery involves: form, color, motion and sleep. Unintentionally these results led to unexpected philosophical implications. Plato’s pivotal concept that ”forms” exist independently of the material world is reversed. Atoms have been considered to be imaginary for 2,000 years but at present they can be photographed, one by one, with electron microscopes. The reason why geometry has led the way in this inquiry is due to the fact that where there is geometry there is utter simplicity coupled to rigorous order that underlies the phenomenon where it is recognized. Order allows variation but imposes at the same time a canalization that is patent in what we call evolution.
Author: Jamie Davies Publisher: Springer Science & Business Media ISBN: 0387308733 Category : Science Languages : en Pages : 255
Book Description
Branching morphogenesis, the creation of branched structures in the body, is a key feature of animal and plant development. This book brings together, for the first time, expert researchers working on a variety of branching systems to present a state-of-the-art view of the mechanisms that control branching morphogenesis. Systems considered range from single cells, to blood vessel and drainage duct systems to entire body plans, and approaches range from observation through experiment to detailed biophysical modelling. The result is an integrated overview of branching.
Author: Christian Foth Publisher: Springer Nature ISBN: 3030272230 Category : Science Languages : en Pages : 247
Book Description
Feathers are one of the most unique characteristics of modern birds and represent the most complex and colourful type of skin derivate within vertebrates, while also fulfilling various biological roles, including flight, thermal insulation, display, and sensory function. For years it was generally assumed that the origin of flight was the main driving force for the evolution of feathers. However, various discoveries of dinosaur species with filamentous body coverings, made over the past 20 years, have fundamentally challenged this idea and produced new evolutionary scenarios for the origin of feathers. This book is devoted to the origin and evolution of feathers, and highlights the impact of palaeontology on this research field by reviewing a number of spectacular fossil discoveries that document the increasing morphological complexity along the evolutionary path to modern birds. Also featuring chapters on fossil feather colours, feather development and its genetic control, the book offers a timely and comprehensive overview of this popular research topic.
Author: Camille Curantz
Author: Camille Curantz
Author: Antonio Lima-de-Faria
Author: Antonio Lima-de-Faria
Author: Jamie Davies
Author: 
Author: Christine Sheppard
Author: Christian Foth
Author: Klaus Mainzer
Author: Ricardo Mallarino
Author: American Institute of Aeronautics and Astronautics