The Experts below are selected from a list of 1320 Experts worldwide ranked by ideXlab platform
Peter Hobbins - One of the best experts on this subject based on the ideXlab platform.
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A Spur to Atavism: Placing Platypus Poison
Journal of the History of Biology, 2015Co-Authors: Peter HobbinsAbstract:For over two centuries, the platypus ( Ornithorhynchus anatinus ) has been constructed and categorized in multiple ways. An unprecedented mélange of anatomical features and physiological functions, it long remained a systematic quandary. Nevertheless, since 1797, naturalists and biologists have pursued two recurring obsessions. Investigations into platypus reproduction and lactation have focused attention largely upon females of the species. Despite its apparent admixture of avian, reptilian and mammalian characters, the platypus was soon placed as a rudimentary mammal – primitive, naïve and harmless. This article pursues a different taxonomic trajectory, concentrating on a specifically male anatomical development: the crural spur and venom gland on the hind legs. Once the defining characteristic of both the platypus and echidna ( Tachyglossus aculeatus ), by 1830 this sexed spur had been largely dismissed as inactive and irrelevant. For a creature regularly depicted as a biological outlier, the systematic and evolutionary implications of platypus poison have remained largely overlooked. In Australia, however, sporadic cases of ‘spiking’ led to consistent homologies being remarked between the platypus crural system and the venom glands of snakes. As with its reproductive reliance upon eggs, possession of an endogenous poison suggested significant reptilian affinities, yet the platypus has rarely been classed as an advanced reptile. Indeed, ongoing uncertainty regarding the biological purpose of the male’s spur has ostensibly posed a directional puzzle. As with so many of its traits, however, platypus poison has been consistently described as a redundant remnant, rather than an emergent feature indicating evolutionary advance.
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A Spur to Atavism: Placing Platypus Poison
Journal of the history of biology, 2015Co-Authors: Peter HobbinsAbstract:For over two centuries, the platypus (Ornithorhynchus anatinus) has been constructed and categorized in multiple ways. An unprecedented melange of anatomical features and physiological functions, it long remained a systematic quandary. Nevertheless, since 1797, naturalists and biologists have pursued two recurring obsessions. Investigations into platypus reproduction and lactation have focused attention largely upon females of the species. Despite its apparent admixture of avian, reptilian and mammalian characters, the platypus was soon placed as a rudimentary mammal--primitive, naive and harmless. This article pursues a different taxonomic trajectory, concentrating on a specifically male anatomical development: the crural spur and venom gland on the hind legs. Once the defining characteristic of both the platypus and echidna (Tachyglossus aculeatus), by 1830 this sexed spur had been largely dismissed as inactive and irrelevant. For a creature regularly depicted as a biological outlier, the systematic and evolutionary implications of platypus poison have remained largely overlooked. In Australia, however, sporadic cases of 'spiking' led to consistent homologies being remarked between the platypus crural system and the venom glands of snakes. As with its reproductive reliance upon eggs, possession of an endogenous poison suggested significant reptilian affinities, yet the platypus has rarely been classed as an advanced reptile. Indeed, ongoing uncertainty regarding the biological purpose of the male's spur has ostensibly posed a directional puzzle. As with so many of its traits, however, platypus poison has been consistently described as a redundant remnant, rather than an emergent feature indicating evolutionary advance.
Lou Charnondeutsch - One of the best experts on this subject based on the ideXlab platform.
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racial theory and Atavism in pardo bazan s short fiction
La Tribuna: Cadernos de Estudos da Casa-Museo Emilia Pardo Bazán, 2016Co-Authors: Lou CharnondeutschAbstract:Emilia Pardo Bazan was an exceptional storyteller in the modern mold, capturing whatever scientism was circulating in popular culture at the moment. In this way she not only showcased her considerable erudition, she challenged her readers to contemplate alternate and sometimes contradictory ways of thinking about racial identity in a modern world in which the subject was widely debated. This essay explores her thinking on race, Atavism, heredity and evolution as exemplified in her short fiction that sometimes contradicted what she expressed in her essays.
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racial theory and Atavism in pardo bazan s short fiction
La Tribuna: cadernos de estudios da Casa Museo Emilia Pardo Bazán, 2012Co-Authors: Lou CharnondeutschAbstract:espanolEmilia Pardo fue una cuentista excepcional en el estilo moderno debido a que incorpo en su ficcion todo tipo de cientifismo que circulara en el momento. De esta forma no solo exhibia su considerable erudicion, sino que invitaba a su publico lector a contemplar modos alternativos y a veces contradictorios de pensar en la identidad racial en la sociedad moderna en la que el tema se debatia calurosamente. Este ensayo explora su pensamiento sobre raza, Atavismo, herencia y evolucion ejemplificado en su ficcion breve en que a veces contradecia lo que escribia en sus ensayos. EnglishEmilia Pardo Bazan was an exceptional storyteller in the modern mold, capturing whatever scientism was circulating in popular culture at the moment. In this way she not only showcased her considerable erudition, she challenged her readers to contemplate alternate and sometimes contradictory ways of thinking about racial ident i ty in a modern world in which the subject was widely debated. This essay explores her thinking on race, Atavism, heredity and evolution as exemplified in her short fiction that sometimes contradicted what she expressed in her essays.
Mark Vincent - One of the best experts on this subject based on the ideXlab platform.
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Cancer adaptations: Atavism, de novo selection, or something in between?
BioEssays : news and reviews in molecular cellular and developmental biology, 2017Co-Authors: Frédéric Thomas, Beata Ujvari, François Renaud, Mark VincentAbstract:From an evolutionary perspective, both Atavism and somatic evolution/convergent evolution theories can account for the consistent occurrence, and astounding attributes of cancers: being able to evolve from a single cell to a complex organized system, and malignant transformations showing significant similarities across organs, individuals, and species. Here, we first provide an overview of these two hypotheses, including the possibility of them not being mutually exclusive, but rather potentially representing the two extremes of a continuum in which the diversity of cancers can emerge. In reviewing the current literature, we also discuss the criteria that should be applied to discriminate between the two competing theories and to determine their relevant contributions to oncogenesis and cancer progression. Finally, we deliberate on the potential applications of this conceptual framework in developing novel treatment strategies.
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Atavism Theory—An Introductory Discourse
Ecology and Evolution of Cancer, 2017Co-Authors: Mark VincentAbstract:The evolutionary nature of cancer has recently commanded increasing attention in the literature; not surprisingly, this has mostly been focused on descriptions of clonal variation, that is, “heterogeneity,'' and what happens mechanistically in established cancers to generate it. This is important and necessary work, since it not only informs clinical decisions, target selection and drug development, but also fleshes out the reality of what has to be explained by any theory of carcinogenesis. However, descriptions and even mechanisms do not by themselves constitute a full understanding of the nature of cancer, and more ominously, may not by themselves lead to a comprehensive solution to the clinical problem of advanced and currently incurable cancer. There is a more fundamental issue that is rarely addressed, concerning the taxonomic status of cancer as distinct from that of the originating host. This issue might be approached by posing four questions dealing, respectively, with cancer’s position on the Tree of Life; why the malignant phenotype is always the same, despite genomic heterogeneity; whether the characteristics of the malignant phenotype are inherently primitive, and/or adapted for archaic geochemistry; and whether the malignant phenotype could ever have served a survival purpose. These questions can only be answered in a tentative and speculative way, but in my opinion do suggest that the stereotypic aspects of the malignant phenotype only make sense in the light of the vastly different oceanic and atmospheric chemistry of the Proterozoic Eon, in which eukaryotic cells first emerged; consequently, the malignant phenotype may constitute some form of atavistic derepression of an archaic genetic program. At the very least, my purpose is to stimulate critical thought about not only the ecology and evolution of cancer as a disease, but also the malignant phenotype as a sustainably viable entity, with an organismal ecology and life history rooted deep in time.
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Atavism theory an introductory discourse
Ecology and Evolution of Cancer, 2017Co-Authors: Mark VincentAbstract:The evolutionary nature of cancer has recently commanded increasing attention in the literature; not surprisingly, this has mostly been focused on descriptions of clonal variation, that is, “heterogeneity,'' and what happens mechanistically in established cancers to generate it. This is important and necessary work, since it not only informs clinical decisions, target selection and drug development, but also fleshes out the reality of what has to be explained by any theory of carcinogenesis. However, descriptions and even mechanisms do not by themselves constitute a full understanding of the nature of cancer, and more ominously, may not by themselves lead to a comprehensive solution to the clinical problem of advanced and currently incurable cancer. There is a more fundamental issue that is rarely addressed, concerning the taxonomic status of cancer as distinct from that of the originating host. This issue might be approached by posing four questions dealing, respectively, with cancer’s position on the Tree of Life; why the malignant phenotype is always the same, despite genomic heterogeneity; whether the characteristics of the malignant phenotype are inherently primitive, and/or adapted for archaic geochemistry; and whether the malignant phenotype could ever have served a survival purpose. These questions can only be answered in a tentative and speculative way, but in my opinion do suggest that the stereotypic aspects of the malignant phenotype only make sense in the light of the vastly different oceanic and atmospheric chemistry of the Proterozoic Eon, in which eukaryotic cells first emerged; consequently, the malignant phenotype may constitute some form of atavistic derepression of an archaic genetic program. At the very least, my purpose is to stimulate critical thought about not only the ecology and evolution of cancer as a disease, but also the malignant phenotype as a sustainably viable entity, with an organismal ecology and life history rooted deep in time.
John M. Opitz - One of the best experts on this subject based on the ideXlab platform.
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Annals of morphology. Atavisms: phylogenetic Lazarus?
American Journal of Medical Genetics Part A, 2013Co-Authors: Ginevra Zanni, John M. OpitzAbstract:Dedication: with highest respect and affection to Prof. Giovanni Neri on the eve of his official administrative retirement as Chair of the Institute of Medical Genetics of the Universita Cattolica of Rome for leadership in medical genetics and medical science and friendship for decades. The concept "Atavism," reversion, throwback, Ruckschlag remains an epistemological challenge in biology; unwise or implausible over-interpretation of a given structure as such has led some to almost total skepticism as to its existence. Originating in botany in the 18th century it became applied to zoology (and humans) with increasing frequency over the last two centuries such that the very concept became widely discredited. Presently, Atavisms have acquired a new life and reconsideration given certain reasonable criteria, including: Homology of structure of the postulated Atavism to that of ancestral fossils or collateral species with plausible soft tissue reconstructions taking into account relationships of parts, obvious sites of origin and insertion of muscles, vascular channels, etc. Most parsimonious, plausible phylogenetic assumptions. Evident rudimentary or vestigial anatomical state in prior generations or in morphogenesis of a given organism. Developmental instability in prior generations, that is, some closely related species facultatively with or without the trait. Genetic identity or phylogenomic similarity inferred in ancestors and corroborated in more or less closely related species. Fluctuating asymmetry may be the basis for the striking evolutionary diversification and common Atavisms in limbs; however, strong selection and developmental constraints would make Atavisms in, for example, cardiac or CNS development less likely. Thus, purported Atavisms must be examined critically in light of the above criteria.
P J Labourg - One of the best experts on this subject based on the ideXlab platform.
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a congenital malformation of the systemic heart complex in sepia officinalis l cephalopoda
Helgoland Marine Research, 1998Co-Authors: Rudolf Schipp, S Von Boletzky, P Jakobs, P J LabourgAbstract:In semi-adultSepia officinalis L. (Cephalopoda) from the Bay of Arcachon (France) a congenital malformation of the systemic heart is described by macro-and microscopical methods. It concerns an atypical doubling of the site of insertion at the cephalic aorta at the apical ventricle. Its comparison with the paired anlagen of the systemic heart complex in normal embryogenesis and the central circulatory system ofNautilus gives rise to interpret it as a form of Atavism. The possible causal role of mutagenic antifoulings is discussed.
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A congenital malformation of the systemic heart complex inSepia officinalis L. (Cephalopoda)
Helgoländer Meeresuntersuchungen, 1998Co-Authors: Rudolf Schipp, P Jakobs, S. Boletzky, P J LabourgAbstract:In semi-adult Sepia officinalis L. (Cephalopoda) from the Bay of Arcachon (France) a congenital malformation of the systemic heart is described by macro-and microscopical methods. It concerns an atypical doubling of the site of insertion at the cephalic aorta at the apical ventricle. Its comparison with the paired anlagen of the systemic heart complex in normal embryogenesis and the central circulatory system of Nautilus gives rise to interpret it as a form of Atavism. The possible causal role of mutagenic antifoulings is discussed.