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1
Root, Zachary D., Claire Gould, Margaux Brewer, David Jandzik e Daniel M. Medeiros. "Comparative Approaches in Vertebrate Cartilage Histogenesis and Regulation: Insights from Lampreys and Hagfishes". Diversity 13, n. 9 (10 settembre 2021): 435. http://dx.doi.org/10.3390/d13090435.
Testo completoAbstract (sommario):
Jawed vertebrates (gnathostomes) have been the dominant lineage of deuterostomes for nearly three hundred fifty million years. Only a few lineages of jawless vertebrates remain in comparison. Composed of lampreys and hagfishes (cyclostomes), these jawless survivors are important systems for understanding the evolution of vertebrates. One focus of cyclostome research has been head skeleton development, as its evolution has been a driver of vertebrate morphological diversification. Recent work has identified hyaline-like cartilage in the oral cirri of the invertebrate chordate amphioxus, making cyclostomes critical for understanding the stepwise acquisition of vertebrate chondroid tissues. Our knowledge of cyclostome skeletogenesis, however, has lagged behind gnathostomes due to the difficulty of manipulating lamprey and hagfish embryos. In this review, we discuss and compare the regulation and histogenesis of cyclostome and gnathostome skeletal tissues. We also survey differences in skeletal morphology that we see amongst cyclostomes, as few elements can be confidently homologized between them. A recurring theme is the heterogeneity of skeletal morphology amongst living vertebrates, despite conserved genetic regulation. Based on these comparisons, we suggest a model through which these mesenchymal connective tissues acquired distinct histologies and that histological flexibility in cartilage existed in the last common ancestor of modern vertebrates.
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Burke, A. C., C. E. Nelson, B. A. Morgan e C. Tabin. "Hox genes and the evolution of vertebrate axial morphology". Development 121, n. 2 (1 febbraio 1995): 333–46. http://dx.doi.org/10.1242/dev.121.2.333.
Testo completoAbstract (sommario):
A common form of evolutionary variation between vertebrate taxa is the different numbers of segments that contribute to various regions of the anterior-posterior axis; cervical vertebrae, thoracic vertebrae, etc. The term ‘transposition’ is used to describe this phenomenon. Genetic experiments with homeotic genes in mice have demonstrated that Hox genes are in part responsible for the specification of segmental identity along the anterior-posterior axis, and it has been proposed that an axial Hox code determines the morphology of individual vertebrae (Kessel, M. and Gruss, P. (1990) Science 249, 347–379). This paper presents a comparative study of the developmental patterns of homeobox gene expression and developmental morphology between animals that have homologous regulatory genes but different morphologies. The axial expression boundaries of 23 Hox genes were examined in the paraxial mesoderm of chick, and 16 in mouse embryos by in situ hybridization and immunolocalization techniques. Hox gene anterior expression boundaries were found to be transposed in concert with morphological boundaries. This data contributes a mechanistic level to the assumed homology of these regions in vertebrates. The recognition of mechanistic homology supports the historical homology of basic patterning mechanisms between all organisms that share these genes.
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Eilam, David. "Comparative Morphology of Locomotion in Vertebrates". Journal of Motor Behavior 27, n. 1 (marzo 1995): 100–111. http://dx.doi.org/10.1080/00222895.1995.9941703.
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Rossi, Valentina, Maria E. McNamara, Sam M. Webb, Shosuke Ito e Kazumasa Wakamatsu. "Tissue-specific geometry and chemistry of modern and fossilized melanosomes reveal internal anatomy of extinct vertebrates". Proceedings of the National Academy of Sciences 116, n. 36 (19 agosto 2019): 17880–89. http://dx.doi.org/10.1073/pnas.1820285116.
Testo completoAbstract (sommario):
Recent discoveries of nonintegumentary melanosomes in extant and fossil amphibians offer potential insights into the physiological functions of melanin not directly related to color production, but the phylogenetic distribution and evolutionary history of these internal melanosomes has not been characterized systematically. Here, we present a holistic method to discriminate among melanized tissues by analyzing the anatomical distribution, morphology, and chemistry of melanosomes in various tissues in a phylogenetically broad sample of extant and fossil vertebrates. Our results show that internal melanosomes in all extant vertebrates analyzed have tissue-specific geometries and elemental signatures. Similar distinct populations of preserved melanosomes in phylogenetically diverse vertebrate fossils often map onto specific anatomical features. This approach also reveals the presence of various melanosome-rich internal tissues in fossils, providing a mechanism for the interpretation of the internal anatomy of ancient vertebrates. Collectively, these data indicate that vertebrate melanins share fundamental physiological roles in homeostasis via the scavenging and sequestering of metals and suggest that intimate links between melanin and metal metabolism in vertebrates have deep evolutionary origins.
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Witter, Menno P., Heidi Kleven e Asgeir Kobro Flatmoen. "Comparative Contemplations on the Hippocampus". Brain, Behavior and Evolution 90, n. 1 (2017): 15–24. http://dx.doi.org/10.1159/000475703.
Testo completoAbstract (sommario):
The hippocampus in mammals is a morphologically well-defined structure, and so are its main subdivisions. To define the homologous structure in other vertebrate clades, using these morphological criteria has been difficult, if not impossible, since the typical mammalian morphology is absent. Although there seems to be consensus that the most medial part of the pallium represents the hippocampus in all vertebrates, there is no consensus on whether all mammalian hippocampal subdivisions are present in the derivatives of the medial pallium in all vertebrate groups. The aim of this paper is to explore the potential relevance of connections to define the hippocampus across vertebrates, with a focus on mammals, reptiles, and birds.
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Henderson, V., e M. J. Song. "Morphology of mitochondria in a teleost, salmo gairdneri". Proceedings, annual meeting, Electron Microscopy Society of America 44 (agosto 1986): 194–95. http://dx.doi.org/10.1017/s0424820100142591.
Testo completoAbstract (sommario):
Mitochondria have been observed at the ultrastructural level as spherical, oval, or sausagelike. Mitochondria average 0.3 to 1.0 um in diameter and 1.0 to 10.0 μm in length. Mitochondria may exceed these dimensions under certian physiological or pathological conditions. The number of mitochondria may reflect the metabolic condition of cells. Cells with high ATP demands display a large number of mitochondria. High energy requirements characterize muscles in both vertebrates and invertebrates. It has been established that yeast cells have but a single mitochondrion. This investigation was designed to ascertain if the numerous mitochondrial profiles represent a single mitochondrion in vertebrate cells.
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Srikulnath, Kornsorn, Syed Farhan Ahmad, Worapong Singchat e Thitipong Panthum. "Why Do Some Vertebrates Have Microchromosomes?" Cells 10, n. 9 (24 agosto 2021): 2182. http://dx.doi.org/10.3390/cells10092182.
Testo completoAbstract (sommario):
With more than 70,000 living species, vertebrates have a huge impact on the field of biology and research, including karyotype evolution. One prominent aspect of many vertebrate karyotypes is the enigmatic occurrence of tiny and often cytogenetically indistinguishable microchromosomes, which possess distinctive features compared to macrochromosomes. Why certain vertebrate species carry these microchromosomes in some lineages while others do not, and how they evolve remain open questions. New studies have shown that microchromosomes exhibit certain unique characteristics of genome structure and organization, such as high gene densities, low heterochromatin levels, and high rates of recombination. Our review focuses on recent concepts to expand current knowledge on the dynamic nature of karyotype evolution in vertebrates, raising important questions regarding the evolutionary origins and ramifications of microchromosomes. We introduce the basic karyotypic features to clarify the size, shape, and morphology of macro- and microchromosomes and report their distribution across different lineages. Finally, we characterize the mechanisms of different evolutionary forces underlying the origin and evolution of microchromosomes.
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Schwenk, Kurt, e Günter P. Wagner. "Visualizing vertebrates: new methods in functional morphology". Journal of Experimental Zoology Part A: Ecological Genetics and Physiology 313A, n. 5 (20 aprile 2010): 241–43. http://dx.doi.org/10.1002/jez.608.
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Miyashita, Tetsuto, Michael I. Coates, Robert Farrar, Peter Larson, Phillip L. Manning, Roy A. Wogelius, Nicholas P. Edwards et al. "Hagfish from the Cretaceous Tethys Sea and a reconciliation of the morphological–molecular conflict in early vertebrate phylogeny". Proceedings of the National Academy of Sciences 116, n. 6 (22 gennaio 2019): 2146–51. http://dx.doi.org/10.1073/pnas.1814794116.
Testo completoAbstract (sommario):
Hagfish depart so much from other fishes anatomically that they were sometimes considered not fully vertebrate. They may represent: (i) an anatomically primitive outgroup of vertebrates (the morphology-based craniate hypothesis); or (ii) an anatomically degenerate vertebrate lineage sister to lampreys (the molecular-based cyclostome hypothesis). This systematic conundrum has become a prominent case of conflict between morphology- and molecular-based phylogenies. To date, the fossil record has offered few insights to this long-branch problem or the evolutionary history of hagfish in general, because unequivocal fossil members of the group are unknown. Here, we report an unequivocal fossil hagfish from the early Late Cretaceous of Lebanon. The soft tissue anatomy includes key attributes of living hagfish: cartilages of barbels, postcranial position of branchial apparatus, and chemical traces of slime glands. This indicates that the suite of characters unique to living hagfish appeared well before Cretaceous times. This new hagfish prompted a reevaluation of morphological characters for interrelationships among jawless vertebrates. By addressing nonindependence of characters, our phylogenetic analyses recovered hagfish and lampreys in a clade of cyclostomes (congruent with the cyclostome hypothesis) using only morphological data. This new phylogeny places the fossil taxon within the hagfish crown group, and resolved other putative fossil cyclostomes to the stem of either hagfish or lamprey crown groups. These results potentially resolve the morphological–molecular conflict at the base of the Vertebrata. Thus, assessment of character nonindependence may help reconcile morphological and molecular inferences for other major discords in animal phylogeny.
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Sakashita, Misaki, Shintaro Yamasaki, Kentaro Yaji, Atsushi Kawamoto e Shigeru Kondo. "Three-dimensional topology optimization model to simulate the external shapes of bone". PLOS Computational Biology 17, n. 6 (16 giugno 2021): e1009043. http://dx.doi.org/10.1371/journal.pcbi.1009043.
Testo completoAbstract (sommario):
Elucidation of the mechanism by which the shape of bones is formed is essential for understanding vertebrate development. Bones support the body of vertebrates by withstanding external loads, such as those imposed by gravity and muscle tension. Many studies have reported that bone formation varies in response to external loads. An increased external load induces bone synthesis, whereas a decreased external load induces bone resorption. This relationship led to the hypothesis that bone shape adapts to external load. In fact, by simulating this relationship through topology optimization, the internal trabecular structure of bones can be successfully reproduced, thereby facilitating the study of bone diseases. In contrast, there have been few attempts to simulate the external structure of bones, which determines vertebrate morphology. However, the external shape of bones may be reproduced through topology optimization because cells of the same type form both the internal and external structures of bones. Here, we constructed a three-dimensional topology optimization model to attempt the reproduction of the external shape of teleost vertebrae. In teleosts, the internal structure of the vertebral bodies is invariable, exhibiting an hourglass shape, whereas the lateral structure supporting the internal structure differs among species. Based on the anatomical observations, we applied different external loads to the hourglass-shaped part. The simulations produced a variety of three-dimensional structures, some of which exhibited several structural features similar to those of actual teleost vertebrae. In addition, by adjusting the geometric parameters, such as the width of the hourglass shape, we reproduced the variation in the teleost vertebrae shapes. These results suggest that a simulation using topology optimization can successfully reproduce the external shapes of teleost vertebrae. By applying our topology optimization model to various bones of vertebrates, we can understand how the external shape of bones adapts to external loads.
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Donatelli, Cassandra M., Alexus S. Roberts, Eric Scott, Kylene DeSmith, Dexter Summers, Layanne Abu-Bader, Dana Baxter et al. "Foretelling the Flex—Vertebral Shape Predicts Behavior and Ecology of Fishes". Integrative and Comparative Biology 61, n. 2 (28 giugno 2021): 414–26. http://dx.doi.org/10.1093/icb/icab110.
Testo completoAbstract (sommario):
Synopsis One key evolutionary innovation that separates vertebrates from invertebrates is the notochord, a central element that provides the stiffness needed for powerful movements. Later, the notochord was further stiffened by the vertebrae, cartilaginous, and bony elements, surrounding the notochord. The ancestral notochord is retained in modern vertebrates as intervertebral material, but we know little about its mechanical interactions with surrounding vertebrae. In this study, the internal shape of the vertebrae—where this material is found—was quantified in 16 species of fishes with various body shapes, swimming modes, and habitats. We used micro-computed tomography to measure the internal shape. We then created and mechanically tested physical models of intervertebral joints. We also mechanically tested actual vertebrae of five species. Material testing shows that internal morphology of the centrum significantly affects bending and torsional stiffness. Finally, we performed swimming trials to gather kinematic data. Combining these data, we created a model that uses internal vertebral morphology to make predictions about swimming kinematics and mechanics. We used linear discriminant analysis (LDA) to assess the relationship between vertebral shape and our categorical traits. The analysis revealed that internal vertebral morphology is sufficient to predict habitat, body shape, and swimming mode in our fishes. This model can also be used to make predictions about swimming in fishes not easily studied in the laboratory, such as deep sea and extinct species, allowing the development of hypotheses about their natural behavior.
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Ezaz, Tariq, e Janine E. Deakin. "Repetitive Sequence and Sex Chromosome Evolution in Vertebrates". Advances in Evolutionary Biology 2014 (11 settembre 2014): 1–9. http://dx.doi.org/10.1155/2014/104683.
Testo completoAbstract (sommario):
Sex chromosomes are the most dynamic entity in any genome having unique morphology, gene content, and evolution. They have evolved multiple times and independently throughout vertebrate evolution. One of the major genomic changes that pertain to sex chromosomes involves the amplification of common repeats. It is hypothesized that such amplification of repeats facilitates the suppression of recombination, leading to the evolution of heteromorphic sex chromosomes through genetic degradation of Y or W chromosomes. Although contrasting evidence is available, it is clear that amplification of simple repetitive sequences played a major role in the evolution of Y and W chromosomes in vertebrates. In this review, we present a brief overview of the repetitive DNA classes that accumulated during sex chromosome evolution, mainly focusing on vertebrates, and discuss their possible role and potential function in this process.
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Peacey, Lorraine, Charlotte Peacey, Adele Gutzinger e Christopher E. Jones. "Copper(II) Binding by the Earliest Vertebrate Gonadotropin-Releasing Hormone, the Type II Isoform, Suggests an Ancient Role for the Metal". International Journal of Molecular Sciences 21, n. 21 (24 ottobre 2020): 7900. http://dx.doi.org/10.3390/ijms21217900.
Testo completoAbstract (sommario):
In vertebrate reproductive biology copper can influence peptide and protein function both in the pituitary and in the gonads. In the pituitary, copper binds to the key reproductive peptides gonadotropin-releasing hormone I (GnRH-I) and neurokinin B, to modify their structure and function, and in the male gonads, copper plays a role in testosterone production, sperm morphology and, thus, fertility. In addition to GnRH-I, most vertebrates express a second isoform, GnRH-II. GnRH-II can promote testosterone release in some species and has other non-reproductive roles. The primary sequence of GnRH-II has remained largely invariant over millennia, and it is considered the ancestral GnRH peptide in vertebrates. In this work, we use a range of spectroscopic techniques to show that, like GnRH-I, GnRH-II can bind copper. Phylogenetic analysis shows that the proposed copper-binding ligands are retained in GnRH-II peptides from all vertebrates, suggesting that copper-binding is an ancient feature of GnRH peptides.
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Pankov, R. G., A. A. Uschewa, B. T. Tasheva e G. G. Markov. "Vertebrate liver cytokeratins: a comparative study". Biochemistry and Cell Biology 65, n. 6 (1 giugno 1987): 547–57. http://dx.doi.org/10.1139/o87-071.
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The structure and composition of intermediate filaments isolated from liver of representatives of different vertebrate classes have been studied by electron microscopy and biochemical and immunochemical methods. It has been shown that the methodological approach for isolation of rat liver intermediate filaments can be efficiently applied to all other classes of vertebrates. The intermediate filaments studied have the same electron microscopic morphology and are species undistinguishable. The molecular weight of intermediate filament proteins varies from 40 000 to 60 000 and their isoelectric point varies from 5.0 to 6.45. Immunological investigations show that in all animals studied the intermediate filaments are built up of cytokeratins belonging to both types of keratins: type I and type II. Only one protein of the type II cytokeratins is present in all vertebrate classes, whereas in lower vertebrates two or even three type I cytokeratins contribute to the structure of liver intermediate filaments. The biochemical and immunochemical results are discussed with regard to the evolution of liver cytokeratins.
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Morrison, Edward E., e Richard M. Costanzo. "Morphology of olfactory epithelium in humans and other vertebrates". Microscopy Research and Technique 23, n. 1 (1 ottobre 1992): 49–61. http://dx.doi.org/10.1002/jemt.1070230105.
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Karatajute-Talimaa, V. "Determination Methods for the Exoskeletal Remains of Early Vertebrates". Fossil Record 1, n. 1 (1 gennaio 1998): 21–51. http://dx.doi.org/10.5194/fr-1-21-1998.
Testo completoAbstract (sommario):
The exoskeleton, consisting of micromeric elements (odontodes) and their derivatives, is characteristic of the most ancient vertebrates. Great morphological and histological variability of discrete exoskeletal microremains makes it difficult to identify them. It is necessary to study not only separate scales or tesserae, but also to get a picture of the squamation in general, because species determined from discrete elements are understood as an assemblage of morphological types. For determination of discrete exoskeletal elements, their morphology, internal structure, defined tissue types of crown and basal plate, types (way) of their growth, system of vascular canals should be studied in addition changes occuring during ontogenetic development of both the dermal skeletal elements and the squamation should be taken in consideration. The material of different groups of early vertebrates (astraspids, tesakoviaspids, heterostracans, thelodonts, mongolepids, chondrichthyans and acanthodians), which were widely distributed in the Early Palaeozoic, are used as examples. <br><br> Ein Hautskelett aus mikromerischen Elementen (Odontodes) und davon abgeleiteten Formen ist für die meisten frühen Vertebraten kennzeichnend. Große morphologische und histologische Variabilität der einzelnen Mikroreste des Hautskeletts bereitet bei ihrer Bestimmung Schwierigkeiten. Es ist notwendig, nicht nur isolierte Schuppen und Tesserae zu untersuchen, sondern man muß sich eine Vorstellung der der gesamten Beschuppung verschaffen, da Arten bestimmt auf isoliertem Material als eine Ansammlung von morphologischen Typen verstanden werden müssen. Bei der Bestimmung isolierter Elemente des Enskeletts sollte man deren Morphologie, innere Struktur, Gewebetypen der Krone und Basalplatte, Arten des Wachstums, Anordnung der Gefäßkanäle und Veränderungen während des Wachstums des Einzelelements und der Gesamtbeschuppung berücksichtigen. Hautskelett-Elemente der verschiedenen Gruppen früher Vertebraten (Astraspiden, Tesakoviaspiden, Heterostraken, Thelodontier, Mongolepiden, Chondrichthyer und Acanthodier), die im frühen Paläozoikum weit verbreitet sind, werden als Beispiele benutzt. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.19980010103" target="_blank">10.1002/mmng.19980010103</a>
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Carniatto, Caio Henrique de Oliveira, Ana Paula Vidotti, Larissa Renata de Oliveira Bianchi e Josiane Medeiros de Mello. "MORFOLOGIA E EVOLUÇÃO DO CORAÇÃO NOS VERTEBRADOS: UMA REVISÃO". Arquivos do Mudi 23, n. 3 (2019): 290–303. http://dx.doi.org/10.4025/arqmudi.v23i3.51553.
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Szczurkowski, A. "Comparative Morphology of Trigeminal Ganglion in Some Species of Vertebrates". Anatomia, Histologia, Embryologia: Journal of Veterinary Medicine Series C 34, s1 (dicembre 2005): 51. http://dx.doi.org/10.1111/j.1439-0264.2005.00669_117.x.
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Cao, Lei, Takeshi Moriishi, Toshihiro Miyazaki, Tadahiro Iimura, Miwako Hamagaki, Ayako Nakane, Yoshihiro Tamamura, Toshihisa Komori e Akira Yamaguchi. "Comparative morphology of the osteocyte lacunocanalicular system in various vertebrates". Journal of Bone and Mineral Metabolism 29, n. 6 (19 aprile 2011): 662–70. http://dx.doi.org/10.1007/s00774-011-0268-6.
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Dunn, Angus M. "SEM guide to the morphology of nematode parasites of vertebrates". British Veterinary Journal 143, n. 5 (settembre 1987): 480–81. http://dx.doi.org/10.1016/0007-1935(87)90027-3.
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Castiello, Marco, Anna Jerve, Maria Grace Burton, Matt Friedman e Martin D. Brazeau. "Endocranial morphology of the petalichthyid placoderm Ellopetalichthys scheii from the Middle Devonian of Arctic Canada, with remarks on the inner ear and neck joint morphology of placoderms". Canadian Journal of Earth Sciences 58, n. 1 (gennaio 2021): 93–104. http://dx.doi.org/10.1139/cjes-2020-0005.
Testo completoAbstract (sommario):
Petalichthyid and “acanthothoracid” placoderms have taken pivotal positions in the debate on placoderm — and, by extension, jawed vertebrate — relationships owing to perceived similarities with certain jawless vertebrates. Neurocranial characters are integral to current hypotheses of early gnathostome relationships. Here, we describe the three-dimensionally preserved neurocranial anatomy of the petalichthyid placoderm Ellopetalichthys scheii (Kiær, 1915), from the Middle Devonian (early Eifelian) of Ellesmere Island, Canada. Using X-ray computed microtomography, we generated three-dimensional reconstructions of the endocranial surfaces, orbital walls, and cranial endocavity. These reconstructions verify the absence of a crus commune of the skeletal labyrinth and the complex shape of the petalichthyid endolympathic duct. Details of the craniothoracic joint and occipital musculature fossae help resolve the problematic comparative anatomy of the occipital surface of petalichthyids. These new data highlight similarities with arthrodire placoderms, consistent with older hypotheses of a sister-group relationship between petalichthyids and that clade.
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Böhmer, Christine, Oliver W. M. Rauhut e Gert Wörheide. "Correlation between Hox code and vertebral morphology in archosaurs". Proceedings of the Royal Society B: Biological Sciences 282, n. 1810 (7 luglio 2015): 20150077. http://dx.doi.org/10.1098/rspb.2015.0077.
Testo completoAbstract (sommario):
The relationship between developmental genes and phenotypic variation is of central interest in evolutionary biology. An excellent example is the role of Hox genes in the anteroposterior regionalization of the vertebral column in vertebrates. Archosaurs (crocodiles, dinosaurs including birds) are highly variable both in vertebral morphology and number. Nevertheless, functionally equivalent Hox genes are active in the axial skeleton during embryonic development, indicating that the morphological variation across taxa is likely owing to modifications in the pattern of Hox gene expression. By using geometric morphometrics, we demonstrate a correlation between vertebral Hox code and quantifiable vertebral morphology in modern archosaurs, in which the boundaries between morphological subgroups of vertebrae can be linked to anterior Hox gene expression boundaries. Our findings reveal homologous units of cervical vertebrae in modern archosaurs, each with their specific Hox gene pattern, enabling us to trace these homologies in the extinct sauropodomorph dinosaurs, a group with highly variable vertebral counts. Based on the quantifiable vertebral morphology, this allows us to infer the underlying genetic mechanisms in vertebral evolution in fossils, which represents not only an important case study, but will lead to a better understanding of the origin of morphological disparity in recent archosaur vertebral columns.
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Žigaitė, Živilė. "Endemic thelodonts (Vertebrata: Thelodonti) from the Lower Silurian of central Asia and southern Siberia". Earth and Environmental Science Transactions of the Royal Society of Edinburgh 104, n. 2 (luglio 2013): 123–43. http://dx.doi.org/10.1017/s1755691013000467.
Testo completoAbstract (sommario):
ABSTRACTNew fossil vertebrate microremains from the Lower Silurian of NW Mongolia, Tuva and S Siberia have been discovered, and previous collections of thelodonts (Vertebrata: Thelodonti) from this region re-studied, figured and described, following recent advances in morphology and systematics of thelodont scales. As a result, six thelodont species are described here and attributed to two families and three genera. An emended diagnosis is given for each species. Morpohological scale varieties of each species are revised, and the squamation types are introduced to the species descriptions, resulting in newly grouped morphological sets of scales. The previously monotypic genus Talimaalepis Žigaitė, 2004, is proposed to contain two different species; therefore, two new combinations of morphological scale sets of two species are described for the first time. Both of them show transitional scale structure between the genera Loganellia (family Loganellidae) and Helenolepis (family Phlebolepididae). Two of the thelodont genera, Angaralepis and Talimaalepis, as well as all the six species, are endemic and not known anywhere else in the world. They are accompanied by a variety of other peculiar early vertebrates, such as mongolepids, two endemic genera of acanthodians, and putative galeaspids. This work enhances our knowledge of early Silurian vertebrate diversity, and provides evidence of regional palaeoenvironmental conditions and palaeogeographical relationships of the Siberia and Tuva terranes.
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Purushothaman, Kathiresan, Jerryl Kim Han Tan, Doreen Lau, Jolly M. Saju, Natascha M. Thevasagayam, Caroline Lei Wee e Shubha Vij. "Feed Restriction Modulates Growth, Gut Morphology and Gene Expression in Zebrafish". International Journal of Molecular Sciences 22, n. 4 (11 febbraio 2021): 1814. http://dx.doi.org/10.3390/ijms22041814.
Testo completoAbstract (sommario):
A reduction in daily caloric or nutrient intake has been observed to promote health benefits in mammals and other vertebrates. Feed Restriction (FR), whereby the overall food intake of the organism is reduced, has been explored as a method to improve metabolic and immune health, as well as to optimize productivity in farming. However, less is known regarding the molecular and physiological consequences of FR. Using the model organism, Danio rerio, we investigated the impact of a short-term (month-long) FR on growth, gut morphology and gene expression. Our data suggest that FR has minimal effects on the average growth rates, but it may affect weight and size heterogeneity in a sex-dependent manner. In the gut, we observed a significant reduction in gut circumference and generally lower mucosal heights, whereas other parameters remained unchanged. Gene Ontology (GO), EuKaryotic Orthologous Groups (KOG), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified numerous metabolic, reproductive, and immune response pathways that were affected by FR. These results broaden our understanding of FR and contribute towards growing knowledge of its effects on vertebrate health.
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Claver, Juan A., e Agustin I. E. Quaglia. "Comparative Morphology, Development, and Function of Blood Cells in Nonmammalian Vertebrates". Journal of Exotic Pet Medicine 18, n. 2 (aprile 2009): 87–97. http://dx.doi.org/10.1053/j.jepm.2009.04.006.
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Coucelo, Josephina, José Coucelo e José Azevedo. "Ultrasonography characterization of heart morphology and blood flow of lower vertebrates". Journal of Experimental Zoology 275, n. 2-3 (1 giugno 1996): 73–82. http://dx.doi.org/10.1002/(sici)1097-010x(19960601/15)275:2/3<73::aid-jez2>3.0.co;2-a.
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Zang, Jingjing, e Stephan C. F. Neuhauss. "Biochemistry and physiology of zebrafish photoreceptors". Pflügers Archiv - European Journal of Physiology 473, n. 9 (17 febbraio 2021): 1569–85. http://dx.doi.org/10.1007/s00424-021-02528-z.
Testo completoAbstract (sommario):
AbstractAll vertebrates share a canonical retina with light-sensitive photoreceptors in the outer retina. These photoreceptors are of two kinds: rods and cones, adapted to low and bright light conditions, respectively. They both show a peculiar morphology, with long outer segments, comprised of ordered stacks of disc-shaped membranes. These discs host numerous proteins, many of which contribute to the visual transduction cascade. This pathway converts the light stimulus into a biological signal, ultimately modulating synaptic transmission. Recently, the zebrafish (Danio rerio) has gained popularity for studying the function of vertebrate photoreceptors. In this review, we introduce this model system and its contribution to our understanding of photoreception with a focus on the cone visual transduction cascade.
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Anjum, Asra, Gayathri Pandurangam, Supriya Garapati, Naveen Bandarupalli, Hajera Rabbani e Divya P. "Morphology and morphometric study of occipital condyles". International Journal of Anatomy and Research 9, n. 1.3 (5 marzo 2021): 7905–11. http://dx.doi.org/10.16965/ijar.2021.107.
Testo completoAbstract (sommario):
Introduction: The occipital condyles are undersurface protruberances of the occipital bone in vertebrates, which articulate with the superior facets of the atlas vertebra. The condyles are oval or reniform in shape, and their anterior extremities directed forward and medially and are closer together than the posterior end. Aim: The aim of the study is to provide important anatomical parameters for lateral transcondylar approach. Materials and Methods: 200 occipital condyles in 100 dry human skulls ( 73 males and 27 females) were studied. The measured parameters included length, width, height, shape, anterior and posterior intercondylar distance, distance between basion and opesthion, distance from anterior tip of the condyle to the basion and opestion and distance from posterior tip to the basion and opesthion. Measurements were made using Vernier Callipers. Results: The mean length, width and height of the occipital condyles in males is greater than females. The anterior intercondylar distance is more in females whereas posterior intercondylar distance is more in males. The mean distance from basion to opesthion / anteroposteriordiamerer of foramen magnum is more in males than in females. The mean distance between the anterior tip of occipital condyles to basion is more in females than in males on both the sides. Conclusion: The knowledge of condylar anatomy helps the surgeon in making important decisions regarding extent and direction of condylar drilling and minimizing injury and retraction of neural structures. KEY WORDS: Occipital Condyles, Foramen Magnum, Intercondylar distance, Basion, Opesthion.
29
Modesto, Sean P., Diane M. Scott e Robert R. Reisz. "Arthropod remains in the oral cavities of fossil reptiles support inference of early insectivory". Biology Letters 5, n. 6 (luglio 2009): 838–40. http://dx.doi.org/10.1098/rsbl.2009.0326.
Testo completoAbstract (sommario):
Inference of feeding preferences in fossil terrestrial vertebrates (tetrapods) has been drawn predominantly from craniodental morphology, and less so from fossil specimens preserving conclusive evidence of diet in the form of oral and/or gut contents. Recently, the pivotal role of insectivory in tetrapod evolution was emphasized by the identification of putative insectivores as the closest relatives of the oldest known herbivorous amniotes. We provide the first compelling evidence for insectivory among early tetrapods on the basis of two 280-million-year-old (late Palaeozoic) fossil specimens of a new species of acleistorhinid parareptile with preserved arthropod cuticle on their toothed palates. Their dental morphology, consisting of homodont marginal dentition with cutting edges and slightly recurved tips, is consistent with an insectivorous diet. The intimate association of arthropod cuticle with the oral region of two small reptiles, from a rich fossil locality that has otherwise not produced invertebrate remains, strongly supports the inference of insectivory in the reptiles. These fossils lend additional support to the hypothesis that the origins and earliest stages of higher vertebrate evolution are associated with relatively small terrestrial insectivores.
30
Kalinina, O. S. "ТАКСОНОМІЧНА ХАРАКТЕРИСТИКА ДНК-ГЕНОМНИХ ВІРУСІВ ХРЕБЕТНИХ ТВАРИН І ЛЮДИНИ". Scientific Messenger of LNU of Veterinary Medicine and Biotechnology 18, n. 2(66) (8 settembre 2016): 83–88. http://dx.doi.org/10.15421/nvlvet6618.
Testo completoAbstract (sommario):
Presented modern taxonomy and nomenclature of the DNA-genomic of viruses of vertebrates animals and humans in accordance with the information ICTV release 2015 (ratification 2016). Described the basic criteria for the classification of viruses: characteristics of the viral genome, the mechanism of replication and virions morphology. Viruses of vertebrates (1120 species) consist of 4 orders, 34 families (12 – DNA-genomic, 22 – RNA-genomic), 11 subfamilies and 219 genera. DNA-genomic viruses of vertebrates (546 species) classified in 1 orders, 12 families, 5 subfamilies and 113 genera. The order Herpesvirales has united family Herpesviridae and Alloherpesviridae. Family Poxviridae, Iridoviridae and Parvoviridae, except of viruses of vertebrates, contain viruses of insects. Described the taxa of viruses:family, subfamily, genera, species. Characterized the basic taxonomic features of DNA-genomic viruses of vertebrates: the shape, size and structure of virions – the presence of outer membrane lipoprotein, capsid symmetry type, the structure of the viral DN and the number of proteins. The attention is focused on the features of reproduction of viruses. The replication of majority DNA-genomic viruses of vertebrates occur in the nucleus of cells, except for members of families Poxviridae and Asfarviridae, which are replicate in the cytoplasm. Yield virions is done due to destruction of cells or budding through the cell membrane (sometimes in combination with exocytosis) depending on the structural organization of the virus.
31
Murdock, Duncan J. E., Ivan J. Sansom e Philip C. J. Donoghue. "Cutting the first ‘teeth’: a new approach to functional analysis of conodont elements". Proceedings of the Royal Society B: Biological Sciences 280, n. 1768 (7 ottobre 2013): 20131524. http://dx.doi.org/10.1098/rspb.2013.1524.
Testo completoAbstract (sommario):
The morphological disparity of conodont elements rivals the dentition of all other vertebrates, yet relatively little is known about their functional diversity. Nevertheless, conodonts are an invaluable resource for testing the generality of functional principles derived from vertebrate teeth, and for exploring convergence in a range of food-processing structures. In a few derived conodont taxa, occlusal patterns have been used to derive functional models. However, conodont elements commonly and primitively exhibit comparatively simple coniform morphologies, functional analysis of which has not progressed much beyond speculation based on analogy. We have generated high-resolution tomographic data for each morphotype of the coniform conodont Panderodus acostatus . Using virtual cross sections, it has been possible to characterize changes in physical properties associated with individual element morphology. Subtle changes in cross-sectional profile have profound implications for the functional performance of individual elements and the apparatus as a whole. This study has implications beyond the ecology of a single conodont taxon. It provides a basis for reinterpreting coniform conodont taxonomy (which is based heavily on cross-sectional profiles), in terms of functional performance and ecology, shedding new light on the conodont fossil record. This technique can also be applied to more derived conodont morphologies, as well as analogous dentitions in other vertebrates and invertebrates.
32
Liu, Quan, Haobo Pan, Zhuofan Chen e Jukka Pekka Matinlinna. "Insight into Bone-Derived Biological Apatite: Ultrastructure and Effect of Thermal Treatment". BioMed Research International 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/601025.
Testo completoAbstract (sommario):
Objectives. This study aims at examining the ultrastructure of bone-derived biological apatite (BAp) from a series of small vertebrates and the effect of thermal treatment on its physiochemical properties.Materials and Methods. Femurs/fin rays and vertebral bodies of 5 kinds of small vertebrates were firstly analyzed with X-ray microtomography. Subsequently, BAp was obtained with thermal treatment and low power plasma ashing, respectively. The properties of BAp, including morphology, functional groups, and crystal characteristics were then analyzed.Results. The bones of grouper and hairtail were mainly composed of condensed bone. Spongy bone showed different distribution in the bones from frog, rat, and pigeon. No significant difference was found in bone mineral density of condensed bone and trabecular thickness of spongy bone. Only platelet-like crystals were observed for BAp obtained by plasma ashing, while rod-like and irregular crystals were both harvested from the bones treated by sintering. A much higher degree of crystallinity and larger crystal size but a lower content of carbonate were detected in the latter.Conclusion. Platelet-like BAp is the common inorganic component of vertebrate bones. BAp distributing in condensed and spongy bone may exhibit differing thermal reactivity. Thermal treatment may alter BAp’sin vivostructure and composition.
33
Berkowitz, Ari. "Physiology and Morphology Indicate That Individual Spinal Interneurons Contribute to Diverse Limb Movements". Journal of Neurophysiology 94, n. 6 (dicembre 2005): 4455–70. http://dx.doi.org/10.1152/jn.00229.2005.
Testo completoAbstract (sommario):
Overlapping neuronal networks have been shown to generate a variety of behaviors or motor patterns in invertebrates, but the evidence for this is more circumstantial in vertebrates. The turtle spinal cord can produce multiple forms of hindlimb scratching movements as well as hindlimb withdrawal, but it is still uncertain whether individual spinal cord interneurons contribute to the motor output for more than one type of limb motor pattern. In this study, individual spinal cord interneurons were recorded intracellularly in vivo in spinal immobilized turtles, and, after characterization, were filled with Neurobiotin. Interneurons that were rhythmically activated during multiple forms of ipsilateral fictive hindlimb scratching often had axon-terminal arborizations in the ventral horn of the spinal cord hindlimb enlargement. This provides some of the strongest evidence to date that interneurons involved in multiple forms of scratching contribute directly to hindlimb motor output. Moreover, most of these interneurons were also active during contralateral fictive scratching and during ipsilateral fictive hindlimb withdrawal, suggesting that they contribute to motor output for these additional behaviors as well. Such interneurons may provide the cellular basis for the contralateral contributions to ipsilateral scratching that have been demonstrated previously. Taken together, these findings suggest that diverse vertebrate limb movements are produced by spinal cord interneuronal networks that include some shared components.
34
Sollid, Jørund, Aina Kjernsli, Paula M. De Angelis, Åsmund K. Røhr e Göran E. Nilsson. "Cell proliferation and gill morphology in anoxic crucian carp". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 289, n. 4 (ottobre 2005): R1196—R1201. http://dx.doi.org/10.1152/ajpregu.00267.2005.
Testo completoAbstract (sommario):
Is DNA replication/cell proliferation in vertebrates possible during anoxia? The oxygen dependence of ribonucleotide reductase (RNR) could lead to a stop in DNA synthesis, thereby making anoxic DNA replication impossible. We have studied this question in an anoxia-tolerant vertebrate, the crucian carp ( Carassius carassius), by examining 5′-bromo-2′-deoxyuridine incorporation and proliferating cell nuclear antigen levels in the gills, intestinal crypts, and liver. We exposed crucian carp to 1 and 7 days of anoxia followed by 7 days of reoxygenation. There was a reduced incidence of S-phase cells (from 12.2 to 5.0%) in gills during anoxia, which coincided with a concomitant increase of G0 cells. Anoxia also decreased the number of S-phase cells in intestine (from 8.1 to 1.8%). No change in the fraction of S-phase cells (∼1%) in liver was found. Thus new S-phase cells after 7 days of anoxia were present in all tissues, revealing a considerable rate of DNA synthesis. Subsequently, the oxygen-dependent subunit of crucian carp RNR (RNRR2) was cloned. We found no differences in amino acids involved in radical generation and availability of the iron center compared with mouse, which could have explained reduced oxygen dependence. Furthermore, the amount of RNRR2 mRNA in gills did not decrease throughout anoxia exposure. These results indicate that crucian carp is able to sustain some cell proliferation in anoxia, possibly because RNRR2 retains its tyrosyl radical in anoxia, and that the replication machinery is still maintained. Although hypoxia triggers a 7.5-fold increase of respiratory surface area in crucian carp, this response was not triggered in anoxia.
35
Moore, Bret A., Innfarn Yoo, Luke P. Tyrrell, Bedrich Benes e Esteban Fernandez-Juricic. "FOVEA: a new program to standardize the measurement of foveal pit morphology". PeerJ 4 (11 aprile 2016): e1785. http://dx.doi.org/10.7717/peerj.1785.
Testo completoAbstract (sommario):
The fovea is one of the most studied retinal specializations in vertebrates, which consists of an invagination of the retinal tissue with high packing of cone photoreceptors, leading to high visual resolution. Between species, foveae differ morphologically in the depth and width of the foveal pit and the steepness of the foveal walls, which could influence visual perception. However, there is no standardized methodology to measure the contour of the foveal pit across species. We present here FOVEA, a program for the quantification of foveal parameters (width, depth, slope of foveal pit) using images from histological cross-sections or optical coherence tomography (OCT). FOVEA is based on a new algorithm to detect the inner retina contour based on the color variation of the image. We evaluated FOVEA by comparing the fovea morphology of two Passerine birds based on histological cross-sections and its performance with data from previously published OCT images. FOVEA detected differences between species and its output was not significantly different from previous estimates using OCT software. FOVEA can be used for comparative studies to better understand the evolution of the fovea morphology in vertebrates as well as for diagnostic purposes in veterinary pathology. FOVEA is freely available for academic use and can be downloaded at:http://estebanfj.bio.purdue.edu/fovea.
36
Yaglov, V. V., e V. N. Yaglova. "NOVEL CONCEPTS IN BIOLOGY OF DIFFUSE ENDOCRINE SYSTEM: RESULTS AND FUTURE INVESTIGATIONS". Annals of the Russian academy of medical sciences 67, n. 4 (23 aprile 2012): 74–81. http://dx.doi.org/10.15690/vramn.v67i4.203.
Testo completoAbstract (sommario):
Diffuse endocrine system is a largest part of endocrine system of vertebrates. Recend findings showed that DES-cells are not neuroectodermal but have ectodermal, mesodermal, and entodermal ontogeny. The article reviews novel concept of diffuse endocrine system anatomy and physiology, functional role of DES hormones and poorly investigated aspects like DES-cell morphology, hormones secretion in normal and pathologic conditions. Further research of diffuse endocrine system has a great significance for biochemistry, morphology, and clinical medicine.
37
Higham, T. E. "The integration of locomotion and prey capture in vertebrates: Morphology, behavior, and performance". Integrative and Comparative Biology 47, n. 1 (10 maggio 2007): 82–95. http://dx.doi.org/10.1093/icb/icm021.
Testo completo
38
Stucky, Richard K. "Paleogene community change among terrestrial vertebrates of the Western Hemisphere". Paleontological Society Special Publications 6 (1992): 282. http://dx.doi.org/10.1017/s247526220000842x.
Testo completoAbstract (sommario):
Paleogene vertebrate communities in North and South America show dramatic changes in taxonomic composition and ecological organization. Worldwide, mammals diversified substantially following dinosaur extinction (Fig. 1). Most families of living vertebrates appear by the end of the Paleogene. In North America, placental omnivores, herbivores and carnivores dominate mammalian communities, but in South America marsupial carnivores and omnivores and placental herbivores dominate them. Immigration from Asia and Europe to North America of taxa from several placental orders (Perissodactyla, Primates, Artiodactyla, Rodentia, Carnivora, Mesonychia, Creodonta) occurred periodically during the Paleogene. South America, however, was completely isolated from the Paleocene to the Oligocene when Rodentia and perhaps Primates first appear. Despite the independent evolutionary histories of these continents, their constituent species show remarkable convergences in morphological adaptations including body size distributions, dental morphology, and other features. Low resolution chronostratigraphic data for the Paleogene of South America precludes correlation with North American faunas. In North America, patterns of diversification and extinction appear to be related to climatic events. Morphological convergences appear to be related to climate and concomitant habitat change, but may also be a function of coevolution via predator-prey interactions and diffuse competition among guild members.
39
Charest, France, Zerina Johanson e Richard Cloutier. "Loss in the making: absence of pelvic fins and presence of paedomorphic pelvic girdles in a Late Devonian antiarch placoderm (jawed stem-gnathostome)". Biology Letters 14, n. 6 (giugno 2018): 20180199. http://dx.doi.org/10.1098/rsbl.2018.0199.
Testo completoAbstract (sommario):
Within jawed vertebrates, pelvic appendages have been modified or lost repeatedly, including in the most phylogenetically basal, extinct, antiarch placoderms. One Early Devonian basal antiarch, Parayunnanolepis , possessed pelvic girdles, suggesting the presence of pelvic appendages at the origin of jawed vertebrates; their absence in more derived antiarchs implies a secondary loss. Recently, paired female genital plates were identified in the Late Devonian antiarch, Bothriolepis canadensis , in the position of pelvic girdles in other placoderms. We studied these putative genital plates along an ontogenetic series of B. canadensis ; ontogenetic changes in their morphology, histology and elemental composition suggest they represent endoskeletal pelvic girdles composed of perichondral and endochondral bone. We suggest that pelvic fins of derived antiarchs were lost, while pelvic girdles were retained, but reduced, relative to Parayunnanolepis . This indicates developmental plasticity and evolutionary lability in pelvic appendages, shortly after these elements evolved at the origin of jawed vertebrates.
40
Bubak, Andrew N., Jaime L. Grace, Michael J. Watt, Kenneth J. Renner e John G. Swallow. "Neurochemistry as a bridge between morphology and behavior: Perspectives on aggression in insects". Current Zoology 60, n. 6 (1 dicembre 2014): 778–90. http://dx.doi.org/10.1093/czoolo/60.6.778.
Testo completoAbstract (sommario):
Abstract Aggression is a common behavioral trait shared in many animals, including both vertebrates and invertebrates. However, the type and intensity of agonistic encounters and displays can vary widely both across and within species, resulting in complicated or subjective interpretations that create difficulties in developing theoretical models that can be widely applied. The need to easily and objectively identify quantifiable behaviors and their associated morphologies becomes especially important when attempting to decipher the neurological mechanisms underlying this complex behavior. Monoamines, neuropeptides, and pheromones have been implicated as important neuromodulators for agonistic displays in both invertebrates and vertebrates. Additionally, recent breakthroughs in insect research have revealed exciting proximate mechanisms important in aggression that may be broadly relevant, due to the relatively high conservation of these neurochemical systems across animal taxa. In this review, we present the latest research demonstrating the importance of monoamines, neuropeptides, and pheromones as neuromodulators for aggression across a variety of insect species. Additionally, we describe the stalk-eyed fly as a model system for studying aggression, which integrates physiological, morphological, and neurochemical approaches in exploring detailed mechanisms responsible for this common yet complex behavior. We conclude with our perspective on the most promising lines of future research aimed at understanding the proximate and ultimate mechanisms underlying aggressive behaviors.
41
Donoghue, Philip C. J. "Growth and patterning in the conodont skeleton". Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 353, n. 1368 (29 aprile 1998): 633–66. http://dx.doi.org/10.1098/rstb.1998.0231.
Testo completoAbstract (sommario):
Recent advances in our understanding of conodont palaeobiology and functional morphology have rendered established hypotheses of element growth untenable. In order to address this problem, hard tissue histology is reviewed paying particular attention to the relationships during growth of the component hard tissues comprising conodont elements, and ignoring a priori assumptions of the homologies of these tissues. Conodont element growth is considered further in terms of the pattern of formation, of which four distinct types are described, all possibly derived from a primitive condition after heterochronic changes in the timing of various developmental stages. It is hoped that this may provide further means of unravelling conodont phylogeny. The manner in which the tissues grew is considered homologous with other vertebrate hard tissues, and the elements appear to have grown in a way similar to the growing scales and growing dentition of other vertebrates.
42
Roberts, R. Michael, Jonathan A. Green e Laura C. Schulz. "The evolution of the placenta". Reproduction 152, n. 5 (novembre 2016): R179—R189. http://dx.doi.org/10.1530/rep-16-0325.
Testo completoAbstract (sommario):
The very apt definition of a placenta is coined by Mossman, namely apposition or fusion of the fetal membranes to the uterine mucosa for physiological exchange. As such, it is a specialized organ whose purpose is to provide continuing support to the developing young. By this definition, placentas have evolved within every vertebrate class other than birds. They have evolved on multiple occasions, often within quite narrow taxonomic groups. As the placenta and the maternal system associate more intimately, such that the conceptus relies extensively on maternal support, the relationship leads to increased conflict that drives adaptive changes on both sides. The story of vertebrate placentation, therefore, is one of convergent evolution at both the macromolecular and molecular levels. In this short review, we first describe the emergence of placental-like structures in nonmammalian vertebrates and then transition to mammals themselves. We close the review by discussing the mechanisms that might have favored diversity and hence evolution of the morphology and physiology of the placentas of eutherian mammals.
43
Jagoe, Charles H., e Dave A. Welter. "Quantitative comparisons of the morphology and ultrastructure of erythrocyte nuclei from seven freshwater fish species". Canadian Journal of Zoology 73, n. 10 (1 ottobre 1995): 1951–59. http://dx.doi.org/10.1139/z95-229.
Testo completoAbstract (sommario):
Chromosome number and genomic DNA content vary widely among fish species, and ploidy can vary within species. This suggests that the size, shape, and morphological features of cell nuclei may also vary. Nucleated erythrocytes of fish are an easily sampled homogeneous population of differentiated cells ideal for inter- and intra-species comparisons. We collected blood samples from largemouth bass (Micropterus salmoides), bluegill (Lepomis macrochirus), chain pickerel (Esox niger), yellow perch (Perca flavescens), mosquitofish (Gambusia holbrooki), redeye bass (Micropterus coosae), and rainbow trout (Oncorhynchus mykiss) and removed cytoplasm and nuclear membranes from blood cells. Individual nuclei were examined and measured using scanning electron microscopy and a computerized image analysis system, and inter- and intra-species differences evaluated by nested analysis of variance. Nuclear size and shape varied significantly among species. Isolated nuclei had conspicuous apertures or holes, and the number and size of these holes also varied significantly among species. Variations in nuclear size and structure within species were small compared with interspecies differences. Little is known of the ultrastructure of erythrocyte nuclei in lower vertebrates, but their structure differs considerably from that of other vertebrate non-erythroid cells, suggesting that the organization of their DNA and associated proteins may be different.
44
Juricek, Ludmila, e Xavier Coumoul. "The Aryl Hydrocarbon Receptor and the Nervous System". International Journal of Molecular Sciences 19, n. 9 (24 agosto 2018): 2504. http://dx.doi.org/10.3390/ijms19092504.
Testo completoAbstract (sommario):
The aryl hydrocarbon receptor (or AhR) is a cytoplasmic receptor of pollutants. It translocates into the nucleus upon binding to its ligands, and forms a heterodimer with ARNT (AhR nuclear translocator). The heterodimer is a transcription factor, which regulates the transcription of xenobiotic metabolizing enzymes. Expressed in many cells in vertebrates, it is mostly present in neuronal cell types in invertebrates, where it regulates dendritic morphology or feeding behavior. Surprisingly, few investigations have been conducted to unravel the function of the AhR in the central or peripheral nervous systems of vertebrates. In this review, we will present how the AhR regulates neural functions in both invertebrates and vertebrates as deduced mainly from the effects of xenobiotics. We will introduce some of the molecular mechanisms triggered by the well-known AhR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), which impact on neuronal proliferation, differentiation, and survival. Finally, we will point out the common features found in mice that are exposed to pollutants, and in AhR knockout mice.
45
Ferrón, Humberto G., Carlos Martínez-Pérez e Héctor Botella. "Ecomorphological inferences in early vertebrates: reconstructing Dunkleosteus terrelli (Arthrodira, Placodermi) caudal fin from palaeoecological data". PeerJ 5 (6 dicembre 2017): e4081. http://dx.doi.org/10.7717/peerj.4081.
Testo completoAbstract (sommario):
Our knowledge about the body morphology of many extinct early vertebrates is very limited, especially in regard to their post-thoracic region. The prompt disarticulation of the dermo-skeletal elements due to taphonomic processes and the lack of a well-ossified endoskeleton in a large number of groups hinder the preservation of complete specimens. Previous reconstructions of most early vertebrates known from partial remains have been wholly based on phylogenetically closely related taxa. However, body design of fishes is determined, to a large extent, by their swimming mode and feeding niche, making it possible to recognise different morphological traits that have evolved several times in non-closely related groups with similar lifestyles. Based on this well-known ecomorphological correlation, here we propose a useful comparative framework established on extant taxa for predicting some anatomical aspects in extinct aquatic vertebrates from palaeoecological data and vice versa. For this, we have assessed the relationship between the locomotory patterns and the morphological variability of the caudal region in extant sharks by means of geometric morphometrics and allometric regression analysis. Multivariate analyses reveal a strong morphological convergence in non-closely related shark species that share similar modes of life, enabling the characterization of the caudal fin morphology of different ecological subgroups. In addition, interspecific positive allometry, affecting mainly the caudal fin span, has been detected. This phenomenon seems to be stronger in sharks with more pelagic habits, supporting its role as a compensation mechanism for the loss of hydrodynamic lift associated with the increase in body size, as previously suggested for many other living and extinct aquatic vertebrates. The quantification of shape change per unit size in each ecological subgroup has allowed us to establish a basis for inferring not only qualitative aspects of the caudal fin morphology of extinct early vertebrates but also to predict absolute values of other variables such as the fin span or the hypocercal and heterocercal angles. The application of this ecomorphological approach to the specific case of Dunkleosteus terrelli has led to a new reconstruction of this emblematic placoderm. Our proposal suggests a caudal fin with a well-developed ventral lobe, narrow peduncle and wide span, in contrast to classical reconstructions founded on the phylogenetic proximity with much smaller placoderms known from complete specimens. Interestingly, this prediction gains support with the recent discovery of fin distal elements (ceratotrichia) in a well preserved D. terrelli, which suggests a possible greater morphological variability in placoderm caudal fins than previously thought.
46
Kalinina, O. S. "Modern taxonomy of viruses of vertebrates". Scientific Messenger of LNU of Veterinary Medicine and Biotechnologies 22, n. 98 (22 agosto 2020): 113–18. http://dx.doi.org/10.32718/nvlvet9820.
Testo completoAbstract (sommario):
The modern taxonomy of viruses of vertebrates is presented according to the information of ICTV issue 07.2019, ratification 03.2020. The leading criteria of taxonomy of viruses are named: type and structure of viral genome, mechanism of replication and morphology of virion. The periods of formation of taxonomic ranks of viruses are characterized: in 1966–1970 genera of viruses were formed, in 1971–1975 – families and subfamilies, since 1990 – orders, in 2018–2019 – realms, kingdoms, phylums, subphylums, classes, suborders, subgenеres. The nomenclature of viruses is described. Viruses belong to the Viruses domain. Viruses of vertebrates (1878 species) belong to 4 realms, 5 kingdoms, 10 phylums, 2 subphylums, 20 classes, 26 orders, 3 suborders, 45 families (of which 15 – DNA-genomic and 30 – RNA-genomic), 33 subfamilies, 345 genera and 49 subgenera. Taxonomic ranks of DNA- and RNA-genomic viruses of vertebrates are described. The DNA-genome family Anelloviridae and the unclassified RNA-genomic genus Deltavirus are not included in any realm. The family Birnaviridae is not classified within the kingdom Orthornavirae. The family of DNA-genomic Hepadnaviridae is included in the realm of RNA-containing viruses Riboviria on the grounds that the replication of hepadnaviruses occurs through the stage of RNA on the principle of reverse transcription, as in the family Retroviridae. The main taxonomic features of DNA- and RNA-genomic viruses of vertebrates are described: type and structure of viral genome (DNA or RNA, number of strands, conformation, fragmentation, polarity), shape and size of virions, presence of outer lipoprotein shell, type of capsid symmetry (spiral, iсosahedral). Some families, in addition to viruses of vertebrates, contain viruses of invertebrates and plants, in particular: families Poxviridae, Iridoviridae, Parvoviridae, Circoviridae, Smacoviridae, Genomoviridae, Rhabdoviridae, Nyamiviridae, Peribunyaviridae, Phenuiviridae, Nairoviviridae, Nodaviridae, Reoviridae and Birnaviridae – viruses of insects; families Genomoviridae, Rhabdoviridae, Phenuiviridae and Reoviridae – viruses of plants; family Nyamiviridae – viruses of nematodes, cestodes, sipunculidеs and echinoderms; family Rhabdoviridae – viruses of nematodes; family Reoviridae – Eriocheir sinensis reovirus; family Birnaviridae – viruses of tellines and rotifers.
47
Rival, David E., Wenchao Yang e Jean-Bernard Caron. "Fish without Tail Fins—Exploring the Function of Tail Morphology of the First Vertebrates". Integrative and Comparative Biology 61, n. 1 (26 febbraio 2021): 37–49. http://dx.doi.org/10.1093/icb/icab004.
Testo completoAbstract (sommario):
Synopsis We use a series of hydrodynamic experiments on abstracted models to explore whether primitive vertebrates may have swum under various conditions without a clearly-differentiated tail fin. Cambrian vertebrates had post-anal stubby tails, some had single dorsal and ventral fins, but none had yet evolved a clearly differentiated caudal fin typical of post-Cambrian fishes, and must have relied on their long and flexible laterally-compressed bodies for locomotion, i.e., by bending their bodies side-to-side in order to propagate waves from head to tail. We approach this problem experimentally based on an abstracted model of Metaspriggina walcotti from the 506-million-year old Burgess Shale by using oscillating thin flexible plates while varying the tail fin geometry from rectangular to uniform, and finally to a no tail–fin condition. Despite a missing tail fin, this study supports the observation that the abstracted Metaspriggina model can generate a strong propulsive force in cruise conditions, both away from, and near the sea bed (in ground effect). However, when the abstracted Metaspriggina model moves in ground effect, a weaker performance is observed, indicating that Metaspriggina may not necessarily have been optimized for swimming near the sea bed. When considering acceleration from rest, we find that the Metaspriggina model's performance is not significantly different from other morphological models (abstracted truncate tail and abstracted heterocercal tail). Statistical analysis shows that morphological parameters, swimming modes, and ground effect all play significant roles in thrust performance. While the exact relationships of Cambrian vertebrates are still debated, as agnathans, they share some general characteristics with modern cyclostomes, in particular an elongate body akin to lampreys. Lampreys, as anguilliform swimmers, are considered to be some of the most efficient swimmers using a particular type of suction thrust induced by the traveling body wave as it travels from head to tail. Our current experiments suggest that Metaspriggina’s ability in acceleration from rest, through possibly a similar type of suction thrust, which is defined as the ability to generate low pressure on upstream facing sections of the body, might have evolved early in response to increasing predator pressure during the Cambrian Explosion.
48
Diel, Patricia, Marvin Kiene, Dominik Martin-Creuzburg e Christian Laforsch. "Knowing the Enemy: Inducible Defences in Freshwater Zooplankton". Diversity 12, n. 4 (7 aprile 2020): 147. http://dx.doi.org/10.3390/d12040147.
Testo completoAbstract (sommario):
Phenotypic plasticity in defensive traits is an appropriate mechanism to cope with the variable hazard of a frequently changing predator spectrum. In the animal kingdom these so-called inducible defences cover the entire taxonomic range from protozoans to vertebrates. The inducible defensive traits range from behaviour, morphology, and life-history adaptations to the activation of specific immune systems in vertebrates. Inducible defences in prey species play important roles in the dynamics and functioning of food webs. Freshwater zooplankton show the most prominent examples of inducible defences triggered by chemical cues, so-called kairomones, released by predatory invertebrates and fish. The objective of this review is to highlight recent progress in research on inducible defences in freshwater zooplankton concerning behaviour, morphology, and life-history, as well as difficulties of studies conducted in a multipredator set up. Furthermore, we outline costs associated with the defences and discuss difficulties as well as the progress made in characterizing defence-inducing cues. Finally, we aim to indicate further possible routes in this field of research and provide a comprehensive table of inducible defences with respect to both prey and predator species.
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Swalla, Billie J., e Andrew B. Smith. "Deciphering deuterostome phylogeny: molecular, morphological and palaeontological perspectives". Philosophical Transactions of the Royal Society B: Biological Sciences 363, n. 1496 (11 gennaio 2008): 1557–68. http://dx.doi.org/10.1098/rstb.2007.2246.
Testo completoAbstract (sommario):
Deuterostomes are a monophyletic group of animals that include the vertebrates, invertebrate chordates, ambulacrarians and xenoturbellids. Fossil representatives from most major deuterostome groups, including some phylum-level crown groups, are found in the Lower Cambrian, suggesting that evolutionary divergence occurred in the Late Precambrian, in agreement with some molecular clock estimates. Molecular phylogenies, larval morphology and the adult heart/kidney complex all support echinoderms and hemichordates as a sister grouping (Ambulacraria). Xenoturbellids are a relatively newly discovered phylum of worm-like deuterostomes that lacks a fossil record, but molecular evidence suggests that these animals are a sister group to the Ambulacraria. Within the chordates, cephalochordates share large stretches of chromosomal synteny with the vertebrates, have a complete Hox complex and are sister group to the vertebrates based on ribosomal and mitochondrial gene evidence. In contrast, tunicates have a highly derived adult body plan and are sister group to the vertebrates based on the analyses of concatenated genomic sequences. Cephalochordates and hemichordates share gill slits and an acellular cartilage, suggesting that the ancestral deuterostome also shared these features. Gene network data suggest that the deuterostome ancestor had an anterior–posterior body axis specified by Hox and Wnt genes, a dorsoventral axis specified by a BMP/chordin gradient, and was bilaterally symmetrical with left–right asymmetry determined by expression of nodal .
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Rücklin, Martin, Philip C. J. Donoghue, John A. Cunningham, Federica Marone e Marco Stampanoni. "Developmental paleobiology of the vertebrate skeleton". Journal of Paleontology 88, n. 4 (luglio 2014): 676–83. http://dx.doi.org/10.1666/13-107.
Testo completoAbstract (sommario):
Studies of the development of organisms can reveal crucial information on homology of structures. Developmental data are not peculiar to living organisms, and they are routinely preserved in the mineralized tissues that comprise the vertebrate skeleton, allowing us to obtain direct insight into the developmental evolution of this most formative of vertebrate innovations. The pattern of developmental processes is recorded in fossils as successive stages inferred from the gross morphology of multiple specimens and, more reliably and routinely, through the ontogenetic stages of development seen in the skeletal histology of individuals. Traditional techniques are destructive and restricted to a 2-D plane with the third dimension inferred. Effective non-invasive methods of visualizing paleohistology to reconstruct developmental stages of the skeleton are necessary.In a brief survey of paleohistological techniques we discuss the pros and cons of these methods. The use of tomographic methods to reconstruct development of organs is exemplified by the study of the placoderm dentition. Testing evidence for the presence of teeth in placoderms, the first jawed vertebrates, we compare the methods that have been used. These include inferring development from morphology, and using serial sectioning, microCT or synchrotron X-ray tomographic microscopy (SRXTM), to reconstruct growth stages and directions of growth. The ensuing developmental interpretations are biased by the methods and degree of inference. The most direct and reliable method is using SRXTM data to trace sclerochronology. The resulting developmental data can be used to resolve homology and test hypotheses on the origin of evolutionary novelties.