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Andreas Wanninger - One of the best experts on this subject based on the ideXlab platform.
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Reconstructing the muscular ground pattern of phylactolaemate bryozoans: first data from gelatinous representatives
BMC Evolutionary Biology, 2017Co-Authors: Natalie Gawin, Andreas Wanninger, Thomas SchwahaAbstract:Phylactolaemata is commonly regarded the earliest branch within Bryozoa and thus the sister group to the other bryozoan taxa, Cyclostomata and Gymnolaemata. Therefore, the taxon is important for the reconstruction of the bryozoan morphological ground pattern. In this study the myoanatomy of Pectinatella magnifica, Cristatella mucedo and Hyalinella punctata was analysed by means of histology, f-actin staining and confocal laser-scanning microscopy in order to fill gaps in knowledge concerning the myoanatomy of Phylactolaemata. The retractor muscles and muscles of the aperture, gut, body wall, Tentacle sheath, lophophore constitute the most prominent muscular subsets in these species. The lophophore shows longitudinal muscle bands in the Tentacles, lophophoral arm muscles, epistome musculature and hitherto undescribed muscles of the ring canal. In general the muscular system of the three species is very similar with differences mainly in the body wall, Tentacle sheath and epistome. The body wall contains an orthogonal grid of musculature. The epistome exhibits either a muscular meshwork in the epistomal wall or muscle fibers traversing the epistomal cavity. The whole Tentacle sheath possesses a regular mesh of muscles in Pectinatella and Cristatella, whereas circular muscles are limited to the Tentacle sheath base in Hyalinella. This study is the first to describe muscles of the ring canal and contributes to reconstructing muscular features for the last common ancestor of all bryozoans. The data available suggest that two longitudinal muscle bands in the Tentacles, as well as retractor muscles and longitudinal and circular muscles in the Tentacle sheath, were present in the last common bryozoan ancestor. Comparisons among bryozoans shows that several apomorphies are present in the myoanatomy of each class- level taxon such as the epistomal musculature and musculature of the lophophoral arms in phylactolaemates, annular muscles in cyclostomes and parietal muscles in gymnolaemates.
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Reconstructing the muscular ground pattern of phylactolaemate bryozoans: first data from gelatinous representatives
BMC, 2017Co-Authors: Natalie Gawin, Andreas Wanninger, Thomas SchwahaAbstract:Abstract Background Phylactolaemata is commonly regarded the earliest branch within Bryozoa and thus the sister group to the other bryozoan taxa, Cyclostomata and Gymnolaemata. Therefore, the taxon is important for the reconstruction of the bryozoan morphological ground pattern. In this study the myoanatomy of Pectinatella magnifica, Cristatella mucedo and Hyalinella punctata was analysed by means of histology, f-actin staining and confocal laser-scanning microscopy in order to fill gaps in knowledge concerning the myoanatomy of Phylactolaemata. Results The retractor muscles and muscles of the aperture, gut, body wall, Tentacle sheath, lophophore constitute the most prominent muscular subsets in these species. The lophophore shows longitudinal muscle bands in the Tentacles, lophophoral arm muscles, epistome musculature and hitherto undescribed muscles of the ring canal. In general the muscular system of the three species is very similar with differences mainly in the body wall, Tentacle sheath and epistome. The body wall contains an orthogonal grid of musculature. The epistome exhibits either a muscular meshwork in the epistomal wall or muscle fibers traversing the epistomal cavity. The whole Tentacle sheath possesses a regular mesh of muscles in Pectinatella and Cristatella, whereas circular muscles are limited to the Tentacle sheath base in Hyalinella. Conclusion This study is the first to describe muscles of the ring canal and contributes to reconstructing muscular features for the last common ancestor of all bryozoans. The data available suggest that two longitudinal muscle bands in the Tentacles, as well as retractor muscles and longitudinal and circular muscles in the Tentacle sheath, were present in the last common bryozoan ancestor. Comparisons among bryozoans shows that several apomorphies are present in the myoanatomy of each class- level taxon such as the epistomal musculature and musculature of the lophophoral arms in phylactolaemates, annular muscles in cyclostomes and parietal muscles in gymnolaemates
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The serotonin-lir nervous system of the Bryozoa (Lophotrochozoa): a general pattern in the Gymnolaemata and implications for lophophore evolution of the phylum
BMC Evolutionary Biology, 2015Co-Authors: Thomas Schwaha, Andreas WanningerAbstract:Background Serotonin represents an evolutionary ancient neurotransmitter that is ubiquitously found among animals including the lophotrochozoan phylum Bryozoa, a group of colonial filter-feeders. Comparatively little is known on their nervous system, and data on their serotonin-lir nervous system currently are mostly limited to the basal phylactolaemates. Previous investigations indicated a common ground-pattern of the serotonin-lir nervous system in these animals, but in order to assess this on a larger scale, 21 gymnolaemate species from 21 genera were comparatively analysed herein. Methods Twenty-one species from 21 gymnolaemate genera were analysed by immunocytochemical stainings and confocal laser scanning microscopy. Results In all species the serotonin-lir signal is concentrated in the cerebral ganglion from where a nerve tract emanates laterally and traverses orally to engulf the foregut. Serotonin-lir perikarya are situated at the base of the Tentacles that almost always correspond to the number of Tentacles minus two. The oral side in almost all species shows three serotonin-lir perikarya followed by a ‘serotonergic gap’ that to our knowledge is not reflected in the morphology of the nervous system. Some species show additional serotonin-lir signal in Tentacle nerves, visceral innervation and pore complexes. Paludicella articulata is exceptional as it shows signal in the latero-visceral nerves with serotonin-lir perikarya in the esophagus, parts of the Tentacle sheath nerves as well as the frontal body wall around the parietal muscle bundles. Conclusions In general, the serotonin-lir nervous system in the Bryozoa shows a consistent pattern among its different clades with few deviations. Preliminary data on phylactolaemates suggest the presence of a ‘serotonergic gap’ similar to gymnolaemates. Both show a subset of oral Tentacles and the remaining Tentacles in gymnolaemates which correspond to the lateral Tentacles of phylactolaemates. The lophophoral concavity lacks serotonin-lir perikarya indicating that due to their larger sizes and increased Tentacle number, the horse-shoe shaped arrangement could represent an apomorphy of phylactolaemates.
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the serotonin lir nervous system of the bryozoa lophotrochozoa a general pattern in the gymnolaemata and implications for lophophore evolution of the phylum
BMC Evolutionary Biology, 2015Co-Authors: Thomas Schwaha, Andreas WanningerAbstract:Serotonin represents an evolutionary ancient neurotransmitter that is ubiquitously found among animals including the lophotrochozoan phylum Bryozoa, a group of colonial filter-feeders. Comparatively little is known on their nervous system, and data on their serotonin-lir nervous system currently are mostly limited to the basal phylactolaemates. Previous investigations indicated a common ground-pattern of the serotonin-lir nervous system in these animals, but in order to assess this on a larger scale, 21 gymnolaemate species from 21 genera were comparatively analysed herein. Twenty-one species from 21 gymnolaemate genera were analysed by immunocytochemical stainings and confocal laser scanning microscopy. In all species the serotonin-lir signal is concentrated in the cerebral ganglion from where a nerve tract emanates laterally and traverses orally to engulf the foregut. Serotonin-lir perikarya are situated at the base of the Tentacles that almost always correspond to the number of Tentacles minus two. The oral side in almost all species shows three serotonin-lir perikarya followed by a ‘serotonergic gap’ that to our knowledge is not reflected in the morphology of the nervous system. Some species show additional serotonin-lir signal in Tentacle nerves, visceral innervation and pore complexes. Paludicella articulata is exceptional as it shows signal in the latero-visceral nerves with serotonin-lir perikarya in the esophagus, parts of the Tentacle sheath nerves as well as the frontal body wall around the parietal muscle bundles. In general, the serotonin-lir nervous system in the Bryozoa shows a consistent pattern among its different clades with few deviations. Preliminary data on phylactolaemates suggest the presence of a ‘serotonergic gap’ similar to gymnolaemates. Both show a subset of oral Tentacles and the remaining Tentacles in gymnolaemates which correspond to the lateral Tentacles of phylactolaemates. The lophophoral concavity lacks serotonin-lir perikarya indicating that due to their larger sizes and increased Tentacle number, the horse-shoe shaped arrangement could represent an apomorphy of phylactolaemates.
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anatomy of the pallial tentacular organs of the scallop nodipecten nodosus linnaeus 1758 bivalvia pectinidae
Zoologischer Anzeiger – A Journal of Comparative Zoology, 2015Co-Authors: Jorge A Audino, Jose Eduardo A R Marian, Andreas Wanninger, Sonia Godoy Bueno Carvalho LopesAbstract:Abstract Tentacular organs comprise a variety of body projections that have specialized functions in several invertebrate phyla. In bivalve mollusks, Tentacles of the mantle margin serve sensorial and secretory functions involved in predator detection and interactions with the surrounding environment. However, their morphological diversity, detailed anatomy, and functional roles have only been scarcely investigated. Bivalves from the family Pectinidae are of particular interest in this context given the diversity of pallial Tentacles, including distinct Tentacle types arising on different mantle folds, and even eye-bearing Tentacles. Combining several microscopy techniques, the present study investigates the anatomy of tentacular organs in postmetamorphic stages (juveniles and adults) of the scallop Nodipecten nodosus (Linnaeus, 1758). Scallop Tentacles are formed shortly after metamorphosis, and except for pigmentation, they grow with no major morphological modifications. Tentacular organs of N. nodosus comprise eye-bearing and short and long Tentacles from the middle mantle fold as well as velar Tentacles from the inner fold. Although all Tentacle types share a common basic structure (i.e., ciliated epithelium, peripheral muscle bundles, and a central nerve), they exhibit marked differences in ciliary distribution, epithelial secretory activity, and type of muscle fibers. Cilia distribution at the distal tip of sensory papillae represents a unique condition for the long Tentacles from the middle mantle fold, and mucous secretion is restricted to the middle fold Tentacles (except for eyestalks). Strikingly, velar Tentacles and middle fold Tentacles exhibit striated and non-striated myofibers, respectively. The data presented herein are discussed in light of the functional anatomy of the bivalve mantle margin.
Thomas Schwaha - One of the best experts on this subject based on the ideXlab platform.
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Reconstructing the muscular ground pattern of phylactolaemate bryozoans: first data from gelatinous representatives
BMC Evolutionary Biology, 2017Co-Authors: Natalie Gawin, Andreas Wanninger, Thomas SchwahaAbstract:Phylactolaemata is commonly regarded the earliest branch within Bryozoa and thus the sister group to the other bryozoan taxa, Cyclostomata and Gymnolaemata. Therefore, the taxon is important for the reconstruction of the bryozoan morphological ground pattern. In this study the myoanatomy of Pectinatella magnifica, Cristatella mucedo and Hyalinella punctata was analysed by means of histology, f-actin staining and confocal laser-scanning microscopy in order to fill gaps in knowledge concerning the myoanatomy of Phylactolaemata. The retractor muscles and muscles of the aperture, gut, body wall, Tentacle sheath, lophophore constitute the most prominent muscular subsets in these species. The lophophore shows longitudinal muscle bands in the Tentacles, lophophoral arm muscles, epistome musculature and hitherto undescribed muscles of the ring canal. In general the muscular system of the three species is very similar with differences mainly in the body wall, Tentacle sheath and epistome. The body wall contains an orthogonal grid of musculature. The epistome exhibits either a muscular meshwork in the epistomal wall or muscle fibers traversing the epistomal cavity. The whole Tentacle sheath possesses a regular mesh of muscles in Pectinatella and Cristatella, whereas circular muscles are limited to the Tentacle sheath base in Hyalinella. This study is the first to describe muscles of the ring canal and contributes to reconstructing muscular features for the last common ancestor of all bryozoans. The data available suggest that two longitudinal muscle bands in the Tentacles, as well as retractor muscles and longitudinal and circular muscles in the Tentacle sheath, were present in the last common bryozoan ancestor. Comparisons among bryozoans shows that several apomorphies are present in the myoanatomy of each class- level taxon such as the epistomal musculature and musculature of the lophophoral arms in phylactolaemates, annular muscles in cyclostomes and parietal muscles in gymnolaemates.
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Reconstructing the muscular ground pattern of phylactolaemate bryozoans: first data from gelatinous representatives
BMC, 2017Co-Authors: Natalie Gawin, Andreas Wanninger, Thomas SchwahaAbstract:Abstract Background Phylactolaemata is commonly regarded the earliest branch within Bryozoa and thus the sister group to the other bryozoan taxa, Cyclostomata and Gymnolaemata. Therefore, the taxon is important for the reconstruction of the bryozoan morphological ground pattern. In this study the myoanatomy of Pectinatella magnifica, Cristatella mucedo and Hyalinella punctata was analysed by means of histology, f-actin staining and confocal laser-scanning microscopy in order to fill gaps in knowledge concerning the myoanatomy of Phylactolaemata. Results The retractor muscles and muscles of the aperture, gut, body wall, Tentacle sheath, lophophore constitute the most prominent muscular subsets in these species. The lophophore shows longitudinal muscle bands in the Tentacles, lophophoral arm muscles, epistome musculature and hitherto undescribed muscles of the ring canal. In general the muscular system of the three species is very similar with differences mainly in the body wall, Tentacle sheath and epistome. The body wall contains an orthogonal grid of musculature. The epistome exhibits either a muscular meshwork in the epistomal wall or muscle fibers traversing the epistomal cavity. The whole Tentacle sheath possesses a regular mesh of muscles in Pectinatella and Cristatella, whereas circular muscles are limited to the Tentacle sheath base in Hyalinella. Conclusion This study is the first to describe muscles of the ring canal and contributes to reconstructing muscular features for the last common ancestor of all bryozoans. The data available suggest that two longitudinal muscle bands in the Tentacles, as well as retractor muscles and longitudinal and circular muscles in the Tentacle sheath, were present in the last common bryozoan ancestor. Comparisons among bryozoans shows that several apomorphies are present in the myoanatomy of each class- level taxon such as the epistomal musculature and musculature of the lophophoral arms in phylactolaemates, annular muscles in cyclostomes and parietal muscles in gymnolaemates
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The serotonin-lir nervous system of the Bryozoa (Lophotrochozoa): a general pattern in the Gymnolaemata and implications for lophophore evolution of the phylum
BMC Evolutionary Biology, 2015Co-Authors: Thomas Schwaha, Andreas WanningerAbstract:Background Serotonin represents an evolutionary ancient neurotransmitter that is ubiquitously found among animals including the lophotrochozoan phylum Bryozoa, a group of colonial filter-feeders. Comparatively little is known on their nervous system, and data on their serotonin-lir nervous system currently are mostly limited to the basal phylactolaemates. Previous investigations indicated a common ground-pattern of the serotonin-lir nervous system in these animals, but in order to assess this on a larger scale, 21 gymnolaemate species from 21 genera were comparatively analysed herein. Methods Twenty-one species from 21 gymnolaemate genera were analysed by immunocytochemical stainings and confocal laser scanning microscopy. Results In all species the serotonin-lir signal is concentrated in the cerebral ganglion from where a nerve tract emanates laterally and traverses orally to engulf the foregut. Serotonin-lir perikarya are situated at the base of the Tentacles that almost always correspond to the number of Tentacles minus two. The oral side in almost all species shows three serotonin-lir perikarya followed by a ‘serotonergic gap’ that to our knowledge is not reflected in the morphology of the nervous system. Some species show additional serotonin-lir signal in Tentacle nerves, visceral innervation and pore complexes. Paludicella articulata is exceptional as it shows signal in the latero-visceral nerves with serotonin-lir perikarya in the esophagus, parts of the Tentacle sheath nerves as well as the frontal body wall around the parietal muscle bundles. Conclusions In general, the serotonin-lir nervous system in the Bryozoa shows a consistent pattern among its different clades with few deviations. Preliminary data on phylactolaemates suggest the presence of a ‘serotonergic gap’ similar to gymnolaemates. Both show a subset of oral Tentacles and the remaining Tentacles in gymnolaemates which correspond to the lateral Tentacles of phylactolaemates. The lophophoral concavity lacks serotonin-lir perikarya indicating that due to their larger sizes and increased Tentacle number, the horse-shoe shaped arrangement could represent an apomorphy of phylactolaemates.
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the serotonin lir nervous system of the bryozoa lophotrochozoa a general pattern in the gymnolaemata and implications for lophophore evolution of the phylum
BMC Evolutionary Biology, 2015Co-Authors: Thomas Schwaha, Andreas WanningerAbstract:Serotonin represents an evolutionary ancient neurotransmitter that is ubiquitously found among animals including the lophotrochozoan phylum Bryozoa, a group of colonial filter-feeders. Comparatively little is known on their nervous system, and data on their serotonin-lir nervous system currently are mostly limited to the basal phylactolaemates. Previous investigations indicated a common ground-pattern of the serotonin-lir nervous system in these animals, but in order to assess this on a larger scale, 21 gymnolaemate species from 21 genera were comparatively analysed herein. Twenty-one species from 21 gymnolaemate genera were analysed by immunocytochemical stainings and confocal laser scanning microscopy. In all species the serotonin-lir signal is concentrated in the cerebral ganglion from where a nerve tract emanates laterally and traverses orally to engulf the foregut. Serotonin-lir perikarya are situated at the base of the Tentacles that almost always correspond to the number of Tentacles minus two. The oral side in almost all species shows three serotonin-lir perikarya followed by a ‘serotonergic gap’ that to our knowledge is not reflected in the morphology of the nervous system. Some species show additional serotonin-lir signal in Tentacle nerves, visceral innervation and pore complexes. Paludicella articulata is exceptional as it shows signal in the latero-visceral nerves with serotonin-lir perikarya in the esophagus, parts of the Tentacle sheath nerves as well as the frontal body wall around the parietal muscle bundles. In general, the serotonin-lir nervous system in the Bryozoa shows a consistent pattern among its different clades with few deviations. Preliminary data on phylactolaemates suggest the presence of a ‘serotonergic gap’ similar to gymnolaemates. Both show a subset of oral Tentacles and the remaining Tentacles in gymnolaemates which correspond to the lateral Tentacles of phylactolaemates. The lophophoral concavity lacks serotonin-lir perikarya indicating that due to their larger sizes and increased Tentacle number, the horse-shoe shaped arrangement could represent an apomorphy of phylactolaemates.
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myoanatomy and serotonergic nervous system of plumatellid and fredericellid phylactolaemata lophotrochozoa ectoprocta
Journal of Morphology, 2012Co-Authors: Thomas Schwaha, Andreas WanningerAbstract:The phylogenetic position of the Ectoprocta within the Lophotrochozoa is discussed controversially. For gaining more insight into ectoproct relationships and comparing it with other potentially related phyla, we analysed the myoanatomy and serotonergic nervous system of adult representatives of the Phylactolaemata (Plumatella emarginata, Plumatellavaihiriae, Plumatella fungosa, Fredericella sultana). The bodywall contains a mesh of circular and longitudinal muscles. On its distal end, the orifice possesses a prominent sphincter and continues into the vestibular wall, which has longitudinal and circular musculature. The Tentacle sheath carries mostly longitudinal muscle fibres in Plumatella sp., whereas F. sultana also possesses regular circular muscle fibres. Three groups of muscles are associated with the lophophore: 1) Lophophoral arm muscles (missing in Fredericella), 2) epistome musculature and 3) Tentacle musculature. The epistome flap is encompassed by smooth muscle fibres. A few fibres extend medially over the ganglion to its proximal floor. Abfrontal Tentacle muscles have diagonally arranged muscle fibres in their proximal region, whereas the distal region is formed by a stack of muscles that resemble an inverted ‘V’. Frontal Tentacle muscles show more variation and either possess one or two bases. The digestive tract possesses circular musculature which is striated except at the intestine where it is composed of smooth muscle fibres. The serotonergic nervous system is concentrated in the cerebral ganglion. From the latter a serotonergic nerve extends to each Tentacle base. In Plumatella the inner row of Tentacles at the lophophoral concavity lacks serotonergic nerves. Bodywall musculature is a common feature in many lophotrochozoan phyla, but among other filter feeders like the Ectoprocta is only present in the ‘lophophorate’ Phoronida. The longitudinal Tentacle musculature is reminiscent of the condition found in phoronids and brachiopods, but differs to entoproct Tentacles. Although this study shows some support for the ‘Lophophorata’, more comparative analyses of possibly related phyla are required. J. Morphol., 2011. © 2011 Wiley Periodicals, Inc.
Reine Talj - One of the best experts on this subject based on the ideXlab platform.
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Integrating safety distances with trajectory planning by modifying the occupancy grid for autonomous vehicle navigation
IEEE Conference on Intelligent Transportation Systems Proceedings ITSC, 2016Co-Authors: Hafida Mouhagir, Francois Aioun, Reine Talj, Veronique Cherfaoui, Franck GuillemardAbstract:The goal of the work in this paper is to use occupancy grid in integrating safety distances with the planning strategy for autonomous vehicle navigation. The challenge is to avoid static and dynamic obstacles at high speed with respect to some specific road rules while following a global reference trajectory. Our local trajectory planning algorithm is based on the method of clothoid Tentacles. It consists on generating clothoid Tentacles in the egocentered reference frame related to the vehicle. Using information provided from sensors, we build an occupancy grid that we modify to take into consideration safety distances.We use this modified occupancy grid to classify each Tentacle as navigable or not navigable. By formulating the problem as Markov Decision Process, only one Tentacle among the navigable ones is chosen as the vehicle local reference trajectory.
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local trajectory planning and tracking for autonomous vehicle navigation using clothoid Tentacles method
IEEE Intelligent Vehicles Symposium, 2015Co-Authors: A. Chebly, Gilles Tagne, Reine TaljAbstract:In general, autonomous navigation requires three key steps, the perception of the environment surrounding the vehicle, the trajectory planning and the actuators control. Numerous works on the localization, perception, generation of occupancy grids and control of vehicles were developed within the ASER team at Heudiasyc laboratory. The work presented in this paper covers, essentially, trajectory planning and is based on the results of these works. The challenge is to avoid static and dynamic obstacles at high speed, using real time algorithms. The planning method developed in this work uses an empirical approach for local path planning. This approach consists on drawing clothoid Tentacles in the egocentered reference frame related to the vehicle. An occupancy grid represents the environment surrounding the vehicle and is considered to be ego-centered around it. Using the information of the occupancy grid, each Tentacle is classified as navigable or not navigable. Among the navigable Tentacles, only one Tentacle is chosen as the vehicle reference trajectory using several criteria. The chosen Tentacle is then applied to the vehicle using a lateral controller based on Immersion and Invariance principle (I&I).
Ilya Borisenko - One of the best experts on this subject based on the ideXlab platform.
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Proliferating activity in a bryozoan lophophore.
PeerJ, 2020Co-Authors: Natalia Shunatova, Ilya BorisenkoAbstract:Bryozoans are small benthic colonial animals; their colonies consist of zooids which are composed of a cystid and polypide. According to morphological and molecular data, three classes of bryozoans are recognized: Phylactolaemata, Gymnolaemata and Stenolaemata. Bryozoans are active suspension feeders and their feeding apparatus, the lophophore, is fringed with a single row of ciliated Tentacles. In gymnolaemates, the lophophore is bell-shaped and its Tentacles may be equal in length (equiTentacled lophophores) or some Tentacles may be longer than others (obliquely truncated lophophores). In encrusting colonies, polypides with obliquely truncated lophophores usually border specific sites of excurrent water outlets (colony periphery and chimneys) where depleted water has to be removed. It is known that during colony astogeny, colony-wide water currents rearrange: new chimneys are formed and/or location of the chimneys within a given colony changes with time. Such rearrangement requires remodeling of the lophophore shape and lengthening of some Tentacles in polypides surrounding water outlets. However, proliferating activity has not been described for bryozoans. Here, we compared the distribution of S-phase and mitotic cells in young and adult polypides in three species of Gymnolaemata. We tested the hypothesis that Tentacle growth/elongation is intercalary and cell proliferation takes place somewhere at the lophophore base because such pattern does not interfere with the feeding process. We also present a detailed description of ultrastructure of two parts of the lophophore base: the oral region and ciliated pits, and uncover the possible function of the latter. The presence of stem cells within the ciliated pits and the oral region of polypides provide evidence that both sites participate in Tentacle elongation. This confirms the suggested hypothesis about intercalary Tentacle growth which provides a potential to alter a lophophore shape in adult polypides according to rearrangement of colony wide water currents during colony astogeny. For the first time deuterosome-like structures were revealed during kinetosome biogenesis in the prospective multiciliated epithelial cells in invertebrates. Tentacle regeneration experiments in Electra pilosa demonstrated that among all epidermal cell types, only non-ciliated cells at the abfrontal Tentacle surface are responsible for wound healing. Ciliated cells on the frontal and lateral Tentacle surfaces are specialized and unable to proliferate, not even under wound healing. Tentacle regeneration in E. pilosa is very slow and similar to the morphallaxis type. We suggest that damaged Tentacles recover their length by a mechanism similar to normal growth, powered by proliferation of cells both within ciliated pits and the oral region.
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Tentacular apparatus ultrastructure in the larva of Bolinopsis infundibulum (Lobata: Ctenophora)
Acta Zoologica, 2013Co-Authors: Ilya Borisenko, Alexander V. EreskovskyAbstract:Most ctenophores have a tentacular apparatus, which plays some role in their feeding. Tentacle structure has been described in adults of only three ctenophore species, but the larval Tentacles have remained completely unstudied. We made a light and electron microscopic study of the tentacular apparatus in the larvae of Bolinopsis infundibulum from the White Sea. The tentacular apparatus of B. infundibulum larvae consists of the Tentacle proper and the Tentacle root. The former contains terminally differentiated cells, while the latter contains stem cells and cells undergoing differentiation. The core of the Tentacle is formed by myo-cytes, and its epidermis contains colloblasts (hunting cells), wall cells, degenerating cask cells, refractive vesicles, and ciliated sensory cells. Stem cells, colloblasts, and cask cells at various stages of differentiation and putative myo-cytes progenitors were revealed in the Tentacle root. Two different populations of the stem cells in the Tentacle root give rise to epidermal (colloblasts and cask cells) and mesogleal (myocytes) cell lines. Nervous elements, glandular cells, and basal lamina were not found. Step-by-step differentiation of colloblasts and cask cells is described.
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Tentacular apparatus ultrastructure in the larva of Bolinopsis infundibulum (Lobata: Ctenophora)
Acta Zoologica, 2011Co-Authors: Ilya Borisenko, Alexander V. EreskovskyAbstract:Borisenko, I. and Ereskovsky, A.V. 2011. Tentacular apparatus ultrastructure in the larva of Bolinopsis infundibulum (Lobata: Ctenophora). —Acta Zoologica (Stockholm) 00: 1–10. Most ctenophores have a tentacular apparatus, which plays some role in their feeding. Tentacle structure has been described in adults of only three ctenophore species, but the larval Tentacles have remained completely unstudied. We made a light and electron microscopic study of the tentacular apparatus in the larvae of Bolinopsis infundibulum from the White Sea. The tentacular apparatus of B. infundibulum larvae consists of the Tentacle proper and the Tentacle root. The former contains terminally differentiated cells, while the latter contains stem cells and cells undergoing differentiation. The core of the Tentacle is formed by myocytes, and its epidermis contains colloblasts (hunting cells), wall cells, degenerating cask cells, refractive vesicles, and ciliated sensory cells. Stem cells, colloblasts, and cask cells at various stages of differentiation and putative myocytes progenitors were revealed in the Tentacle root. Two different populations of the stem cells in the Tentacle root give rise to epidermal (colloblasts and cask cells) and mesogleal (myocytes) cell lines. Nervous elements, glandular cells, and basal lamina were not found. Step-by-step differentiation of colloblasts and cask cells is described.
G. Kass-simon - One of the best experts on this subject based on the ideXlab platform.
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Extraocular spectral photosensitivity in the Tentacles of Hydra vulgaris.
Comparative biochemistry and physiology. Part A Molecular & integrative physiology, 2015Co-Authors: Stephanie L. Guertin, G. Kass-simonAbstract:Abstract Previous electrophysiological studies on the cnidarian Hydra vulgaris have shown that hydra have a highly developed and specific photoresponse despite their lack of any structure recognizable as a traditional photoreceptor. In an effort to identify the site of hydra's photoreceptors, we recorded extracellularly from single excised Tentacles and from ablated hypostomes lacking Tentacles in absolute darkness and during exposure to light of various wavelengths. During recording, after an initial period of absolute darkness, Tentacles or hypostomes were exposed to light from 450 nm to 600 nm, red, and white light. Exposure to light caused a change in the pattern and frequency of impulses in the Tentacles that varied with color. The number of large Tentacle pulses (TPs) increased at 550 and 600 nm relative to darkness, whereas the number of small Tentacle pulses (STPs) tended to decrease in 500 nm light. Impulse frequency was significantly different among the different wavelengths. In addition to bursts of Tentacle contraction pulses, long trains of pulses were observed. A change in lighting caused a switch from bursting to trains or vice versa. In contrast to excised Tentacles, no change in electrical activity was seen in ablated hypostomes at any of the wavelengths relative to each other or relative to darkness. These results indicate that isolated Tentacles can distinguish among and respond to various colors across the visible spectrum and suggest that electromagnetic information is transmitted from the Tentacles to the hypostome where it may be integrated by the hypostomal nervous system, ultimately contributing to hydra's photoreceptive behavior.
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Extraocular spectral photosensitivity in the Tentacles of Hydra vulgaris Part A Molecular & integrative physiology
Comparative Biochemistry and Physiology, 2015Co-Authors: Stephanie L. Guertin, G. Kass-simonAbstract:Previous electrophysiological studies on the cnidarian Hydra vulgaris have shown that hydra have a highly developed and specific photoresponse despite their lack of any structure recognizable as a traditional photoreceptor. In an effort to identify the site of hydra's photoreceptors, we recorded extracellularly from single excised Tentacles and from ablated hypostomes lacking Tentacles in absolute darkness and during exposure to light of various wavelengths. During recording, after an initial period of absolute darkness, Tentacles or hypostomes were exposed to light from 450nm to 600nm, red, and white light. Exposure to light caused a change in the pattern and frequency of impulses in the Tentacles that varied with color. The number of large Tentacle pulses (TPs) increased at 550 and 600nm relative to darkness, whereas the number of small Tentacle pulses (STPs) tended to decrease in 500nm light. Impulse frequency was significantly different among the different wavelengths. In addition to bursts of Tentacle contraction pulses, long trains of pulses were observed. A change in lighting caused a switch from bursting to trains or vice versa. In contrast to excised Tentacles, no change in electrical activity was seen in ablated hypostomes at any of the wavelengths relative to each other or relative to darkness. These results indicate that isolated Tentacles can distinguish among and respond to various colors across the visible spectrum and suggest that electromagnetic information is transmitted from the Tentacles to the hypostome where it may be integrated by the hypostomal nervous system, ultimately contributing to hydra's photoreceptive behavior.
