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Shigeru Kuratani - One of the best experts on this subject based on the ideXlab platform.
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genetic mechanism for the Cyclostome cerebellar neurons reveals early evolution of the vertebrate cerebellum
Frontiers in Cell and Developmental Biology, 2021Co-Authors: Fumiaki Sugahara, Shigehiro Kuraku, Shigeru Kuratani, Juan Pascualanaya, Yasunori MurakamiAbstract:The vertebrate cerebellum arises at the dorsal part of rhombomere 1, induced by signals from the isthmic organizer. Two major cerebellar neuronal subtypes, granule cells (excitatory) and Purkinje cells (inhibitory), are generated from the anterior rhombic lip and the ventricular zone, respectively. This regionalization and the way it develops are shared in all extant jawed vertebrates (gnathostomes). However, very little is known about early evolution of the cerebellum. The lamprey, an extant jawless vertebrate lineage or Cyclostome, possesses an undifferentiated, plate-like cerebellum, whereas the hagfish, another Cyclostome lineage, is thought to lack a cerebellum proper. In this study, we found that hagfish Atoh1 and Wnt1 genes are co-expressed in the rhombic lip, and Ptf1a is expressed ventrally to them, confirming the existence of r1's rhombic lip and the ventricular zone in Cyclostomes. In later stages, lamprey Atoh1 is downregulated in the posterior r1, in which the NeuroD increases, similar to the differentiation process of cerebellar granule cells in gnathostomes. Also, a continuous Atoh1-positive domain in the rostral r1 is reminiscent of the primordium of valvula cerebelli of ray-finned fishes. Lastly, we detected a GAD-positive domain adjacent to the Ptf1a-positive ventricular zone in lampreys, suggesting that the Ptf1a-positive cells differentiate into some GABAergic inhibitory neurons such as Purkinje and other inhibitory neurons like in gnathostomes. Altogether, we conclude that the ancestral genetic programs for the formation of a distinct cerebellum were established in the last common ancestor of vertebrates.
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Image_3_Genetic Mechanism for the Cyclostome Cerebellar Neurons Reveals Early Evolution of the Vertebrate Cerebellum.TIF
'Frontiers Media SA', 2021Co-Authors: Fumiaki Sugahara, Shigehiro Kuraku, Shigeru Kuratani, Juan Pascual-anaya, Yasunori MurakamiAbstract:The vertebrate cerebellum arises at the dorsal part of rhombomere 1, induced by signals from the isthmic organizer. Two major cerebellar neuronal subtypes, granule cells (excitatory) and Purkinje cells (inhibitory), are generated from the anterior rhombic lip and the ventricular zone, respectively. This regionalization and the way it develops are shared in all extant jawed vertebrates (gnathostomes). However, very little is known about early evolution of the cerebellum. The lamprey, an extant jawless vertebrate lineage or Cyclostome, possesses an undifferentiated, plate-like cerebellum, whereas the hagfish, another Cyclostome lineage, is thought to lack a cerebellum proper. In this study, we found that hagfish Atoh1 and Wnt1 genes are co-expressed in the rhombic lip, and Ptf1a is expressed ventrally to them, confirming the existence of r1’s rhombic lip and the ventricular zone in Cyclostomes. In later stages, lamprey Atoh1 is downregulated in the posterior r1, in which the NeuroD increases, similar to the differentiation process of cerebellar granule cells in gnathostomes. Also, a continuous Atoh1-positive domain in the rostral r1 is reminiscent of the primordium of valvula cerebelli of ray-finned fishes. Lastly, we detected a GAD-positive domain adjacent to the Ptf1a-positive ventricular zone in lampreys, suggesting that the Ptf1a-positive cells differentiate into some GABAergic inhibitory neurons such as Purkinje and other inhibitory neurons like in gnathostomes. Altogether, we conclude that the ancestral genetic programs for the formation of a distinct cerebellum were established in the last common ancestor of vertebrates.
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Table_1_Genetic Mechanism for the Cyclostome Cerebellar Neurons Reveals Early Evolution of the Vertebrate Cerebellum.docx
'Frontiers Media SA', 2021Co-Authors: Fumiaki Sugahara, Shigehiro Kuraku, Shigeru Kuratani, Juan Pascual-anaya, Yasunori MurakamiAbstract:The vertebrate cerebellum arises at the dorsal part of rhombomere 1, induced by signals from the isthmic organizer. Two major cerebellar neuronal subtypes, granule cells (excitatory) and Purkinje cells (inhibitory), are generated from the anterior rhombic lip and the ventricular zone, respectively. This regionalization and the way it develops are shared in all extant jawed vertebrates (gnathostomes). However, very little is known about early evolution of the cerebellum. The lamprey, an extant jawless vertebrate lineage or Cyclostome, possesses an undifferentiated, plate-like cerebellum, whereas the hagfish, another Cyclostome lineage, is thought to lack a cerebellum proper. In this study, we found that hagfish Atoh1 and Wnt1 genes are co-expressed in the rhombic lip, and Ptf1a is expressed ventrally to them, confirming the existence of r1’s rhombic lip and the ventricular zone in Cyclostomes. In later stages, lamprey Atoh1 is downregulated in the posterior r1, in which the NeuroD increases, similar to the differentiation process of cerebellar granule cells in gnathostomes. Also, a continuous Atoh1-positive domain in the rostral r1 is reminiscent of the primordium of valvula cerebelli of ray-finned fishes. Lastly, we detected a GAD-positive domain adjacent to the Ptf1a-positive ventricular zone in lampreys, suggesting that the Ptf1a-positive cells differentiate into some GABAergic inhibitory neurons such as Purkinje and other inhibitory neurons like in gnathostomes. Altogether, we conclude that the ancestral genetic programs for the formation of a distinct cerebellum were established in the last common ancestor of vertebrates.
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Inner ear development in Cyclostomes and evolution of the vertebrate semicircular canals
Nature, 2019Co-Authors: Shinnosuke Higuchi, Yasuhiro Oisi, Fumiaki Sugahara, Juan Pascual-anaya, Wataru Takagi, Shigeru KurataniAbstract:Jawed vertebrates have inner ears with three semicircular canals, the presence of which has been used as a key to understanding evolutionary relationships. Ostracoderms, the jawless stem gnathostomes, had only two canals and lacked the lateral canal^ 1 – 3 . Lampreys, which are modern Cyclostomes, are generally thought to possess two semicircular canals whereas the hagfishes—which are also Cyclostomes—have only a single canal, which used to be regarded as a more primitive trait^ 1 , 4 . However, recent molecular and developmental analyses have strongly supported the monophyly of Cyclostomes^ 5 – 7 , which has left the evolutionary trajectory of the vertebrate inner ear unclear^ 8 . Here we show the differentiation of the otic vesicle of the lamprey Lethenteron camtschaticum and inshore hagfish Eptatretus burgeri . This is the first time, to our knowledge, that the development of the hagfish inner ear is reported. We found that canal development in the lamprey starts with two depressions—which is reminiscent of the early developmental pattern of the inner ear in modern gnathostomes. These Cyclostome otic vesicles show a pattern of expression of regulatory genes, including OTX genes, that is comparable to that of gnathosomes. Although two depressions appear in the lamprey vesicle, they subsequently fuse to form a single canal that is similar to that of hagfishes. Complete separation of the depressions results in anterior and posterior canals in gnathostomes. The single depression of the vesicle in hagfishes thus appears to be a secondarily derived trait. Furthermore, the lateral canal in crown gnathostomes was acquired secondarily—not by de novo acquisition of an OTX expression domain, but by the evolution of a developmental program downstream of the OTX genes. The differentiation of the inner ear in the lamprey Lethenteron camtschaticum and hagfish Eptatretus burgeri sheds light on the evolution of the semicircular canals of jawed vertebrates.
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evolution of the vertebrate cranium viewed from hagfish developmental studies
Zoological Science, 2016Co-Authors: Shigeru Kuratani, Yasuhiro OisiAbstract:Our knowledge of vertebrate cranium evolution has relied largely on the study of gnathostomes. Recent evolutionary and developmental studies of Cyclostomes have shed new light on the history of the vertebrate skull. The recent ability to obtain embryos of the hagfish, Eptatretus burgeri, has enabled new studies which have suggested an embryonic morphological pattern (the “Cyclostome pattern”) of craniofacial development. This pattern is shared by Cyclostomes, but not by modern jawed vertebrates. Because this pattern of embryonic head development is thought to be present in some stem gnathostomes (ostracoderms), it is possible that the Cyclostome pattern represents the vertebrate ancestral pattern. The study of Cyclostomes may thus lead to an understanding of the most ancestral basis of craniofacial development. In this review, we summarize the development of the hagfish chondrocranium in light of the Cyclostome pattern, present an updated comparison of the Cyclostome chondrocranium, and discuss several aspects of the evolution and development of the vertebrate skull.
Shigehiro Kuraku - One of the best experts on this subject based on the ideXlab platform.
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genetic mechanism for the Cyclostome cerebellar neurons reveals early evolution of the vertebrate cerebellum
Frontiers in Cell and Developmental Biology, 2021Co-Authors: Fumiaki Sugahara, Shigehiro Kuraku, Shigeru Kuratani, Juan Pascualanaya, Yasunori MurakamiAbstract:The vertebrate cerebellum arises at the dorsal part of rhombomere 1, induced by signals from the isthmic organizer. Two major cerebellar neuronal subtypes, granule cells (excitatory) and Purkinje cells (inhibitory), are generated from the anterior rhombic lip and the ventricular zone, respectively. This regionalization and the way it develops are shared in all extant jawed vertebrates (gnathostomes). However, very little is known about early evolution of the cerebellum. The lamprey, an extant jawless vertebrate lineage or Cyclostome, possesses an undifferentiated, plate-like cerebellum, whereas the hagfish, another Cyclostome lineage, is thought to lack a cerebellum proper. In this study, we found that hagfish Atoh1 and Wnt1 genes are co-expressed in the rhombic lip, and Ptf1a is expressed ventrally to them, confirming the existence of r1's rhombic lip and the ventricular zone in Cyclostomes. In later stages, lamprey Atoh1 is downregulated in the posterior r1, in which the NeuroD increases, similar to the differentiation process of cerebellar granule cells in gnathostomes. Also, a continuous Atoh1-positive domain in the rostral r1 is reminiscent of the primordium of valvula cerebelli of ray-finned fishes. Lastly, we detected a GAD-positive domain adjacent to the Ptf1a-positive ventricular zone in lampreys, suggesting that the Ptf1a-positive cells differentiate into some GABAergic inhibitory neurons such as Purkinje and other inhibitory neurons like in gnathostomes. Altogether, we conclude that the ancestral genetic programs for the formation of a distinct cerebellum were established in the last common ancestor of vertebrates.
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Table_1_Genetic Mechanism for the Cyclostome Cerebellar Neurons Reveals Early Evolution of the Vertebrate Cerebellum.docx
'Frontiers Media SA', 2021Co-Authors: Fumiaki Sugahara, Shigehiro Kuraku, Shigeru Kuratani, Juan Pascual-anaya, Yasunori MurakamiAbstract:The vertebrate cerebellum arises at the dorsal part of rhombomere 1, induced by signals from the isthmic organizer. Two major cerebellar neuronal subtypes, granule cells (excitatory) and Purkinje cells (inhibitory), are generated from the anterior rhombic lip and the ventricular zone, respectively. This regionalization and the way it develops are shared in all extant jawed vertebrates (gnathostomes). However, very little is known about early evolution of the cerebellum. The lamprey, an extant jawless vertebrate lineage or Cyclostome, possesses an undifferentiated, plate-like cerebellum, whereas the hagfish, another Cyclostome lineage, is thought to lack a cerebellum proper. In this study, we found that hagfish Atoh1 and Wnt1 genes are co-expressed in the rhombic lip, and Ptf1a is expressed ventrally to them, confirming the existence of r1’s rhombic lip and the ventricular zone in Cyclostomes. In later stages, lamprey Atoh1 is downregulated in the posterior r1, in which the NeuroD increases, similar to the differentiation process of cerebellar granule cells in gnathostomes. Also, a continuous Atoh1-positive domain in the rostral r1 is reminiscent of the primordium of valvula cerebelli of ray-finned fishes. Lastly, we detected a GAD-positive domain adjacent to the Ptf1a-positive ventricular zone in lampreys, suggesting that the Ptf1a-positive cells differentiate into some GABAergic inhibitory neurons such as Purkinje and other inhibitory neurons like in gnathostomes. Altogether, we conclude that the ancestral genetic programs for the formation of a distinct cerebellum were established in the last common ancestor of vertebrates.
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Image_3_Genetic Mechanism for the Cyclostome Cerebellar Neurons Reveals Early Evolution of the Vertebrate Cerebellum.TIF
'Frontiers Media SA', 2021Co-Authors: Fumiaki Sugahara, Shigehiro Kuraku, Shigeru Kuratani, Juan Pascual-anaya, Yasunori MurakamiAbstract:The vertebrate cerebellum arises at the dorsal part of rhombomere 1, induced by signals from the isthmic organizer. Two major cerebellar neuronal subtypes, granule cells (excitatory) and Purkinje cells (inhibitory), are generated from the anterior rhombic lip and the ventricular zone, respectively. This regionalization and the way it develops are shared in all extant jawed vertebrates (gnathostomes). However, very little is known about early evolution of the cerebellum. The lamprey, an extant jawless vertebrate lineage or Cyclostome, possesses an undifferentiated, plate-like cerebellum, whereas the hagfish, another Cyclostome lineage, is thought to lack a cerebellum proper. In this study, we found that hagfish Atoh1 and Wnt1 genes are co-expressed in the rhombic lip, and Ptf1a is expressed ventrally to them, confirming the existence of r1’s rhombic lip and the ventricular zone in Cyclostomes. In later stages, lamprey Atoh1 is downregulated in the posterior r1, in which the NeuroD increases, similar to the differentiation process of cerebellar granule cells in gnathostomes. Also, a continuous Atoh1-positive domain in the rostral r1 is reminiscent of the primordium of valvula cerebelli of ray-finned fishes. Lastly, we detected a GAD-positive domain adjacent to the Ptf1a-positive ventricular zone in lampreys, suggesting that the Ptf1a-positive cells differentiate into some GABAergic inhibitory neurons such as Purkinje and other inhibitory neurons like in gnathostomes. Altogether, we conclude that the ancestral genetic programs for the formation of a distinct cerebellum were established in the last common ancestor of vertebrates.
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evidence from Cyclostomes for complex regionalization of the ancestral vertebrate brain
Nature, 2016Co-Authors: Fumiaki Sugahara, Yasuhiro Oisi, Shigehiro Kuraku, Juan Pascualanaya, Shinichi Aota, Noritaka Adachi, Wataru Takagi, Tamami Hirai, Noboru Sato, Yasunori MurakamiAbstract:The brain of the hagfish, a Cyclostome related to the lamprey, develops domains equivalent to the median ganglionic eminence and the rhombic lip, resembling the brains of gnathostomes (jawed vertebrates), suggesting that brain regionalization in jawed vertebrates occurred before the divergence of Cyclostomes and gnathostomes more than 500 million years ago. The brains of vertebrates are much more complex than those of their immediate invertebrate relations — tunicates and the amphioxus — raising questions about the origins and development of the brain. The jawless lamprey, an ancient vertebrate, was also thought to have a primitive 'ancestral' brain. In particular, the embryonic lamprey was thought to have characteristics resembling those of mutant mice lacking a structure called the medial ganglionic eminence (MGE). Shigeru Kuratani and colleagues now show that the hagfish, a close relative of the lamprey, develops domains equivalent to the MGE and also the rhombic lip, resembling the brains of jawed vertebrates (gnathostomes). A closer look at lampreys reveals that they too have similar structures. These findings suggest that brain regionalization as seen in jawed vertebrates dates back to the latest vertebrate ancestor prior to the divergence of Cyclostomes and gnathostomes more than 500 million years ago. The vertebrate brain is highly complex, but its evolutionary origin remains elusive. Because of the absence of certain developmental domains generally marked by the expression of regulatory genes, the embryonic brain of the lamprey, a jawless vertebrate, had been regarded as representing a less complex, ancestral state of the vertebrate brain. Specifically, the absence of a Hedgehog- and Nkx2.1-positive domain in the lamprey subpallium was thought to be similar to mouse mutants in which the suppression of Nkx2-1 leads to a loss of the medial ganglionic eminence1,2. Here we show that the brain of the inshore hagfish (Eptatretus burgeri), another Cyclostome group, develops domains equivalent to the medial ganglionic eminence and rhombic lip, resembling the gnathostome brain. Moreover, further investigation of lamprey larvae revealed that these domains are also present, ruling out the possibility of convergent evolution between hagfish and gnathostomes. Thus, brain regionalization as seen in crown gnathostomes is not an evolutionary innovation of this group, but dates back to the latest vertebrate ancestor before the divergence of Cyclostomes and gnathostomes more than 500 million years ago.
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Evolution of retinoic acid receptors in chordates: insights from three lamprey species, Lampetra fluviatilis, Petromyzon marinus, and Lethenteron japonicum
EvoDevo, 2015Co-Authors: Florent Campo-paysaa, David Jandzik, Maria V Cattell, Haley C Neef, James A Langeland, Shigeru Kuratani, Yoko Takio-ogawa, Daniel M Medeiros, Sylvie Mazan, Shigehiro KurakuAbstract:Background : Retinoic acid (RA) signaling controls many developmental processes in chordates, from early axis specification to late organogenesis. The functions of RA are chiefly mediated by a subfamily of nuclear hormone receptors, the retinoic acid receptors (RARs), that act as ligand-activated transcription factors. While RARs have been extensively studied in jawed vertebrates (that is, gnathostomes) and invertebrate chordates, very little is known about the repertoire and developmental roles of RARs in Cyclostomes, which are extant jawless vertebrates. Here, we present the first extensive study of Cyclostome RARs focusing on three different lamprey species: the European freshwater lamprey, Lampetra fluviatilis, the sea lamprey, Petromyzon marinus, and the Japanese lamprey, Lethenteron japonicum. Results : We identified four rar paralogs (rar1, rar2, rar3, and rar4) in each of the three lamprey species, and phylogenetic analyses indicate a complex evolutionary history of lamprey rar genes including the origin of rar1 and rar4 by lineage-specific duplication after the lamprey-hagfish split. We further assessed their expression patterns during embryonic development by in situ hybridization. The results show that lamprey rar genes are generally characterized by dynamic and highly specific expression domains in different embryonic tissues. In particular, lamprey rar genes exhibit combinatorial expression domains in the anterior central nervous system (CNS) and the pharyngeal region. Conclusions : Our results indicate that the genome of lampreys encodes at least four rar genes and suggest that the lamprey rar complement arose from vertebrate-specific whole genome duplications followed by a lamprey-specific duplication event. Moreover, we describe a combinatorial code of lamprey rar expression in both anterior CNS and pharynx resulting from dynamic and highly specific expression patterns during embryonic development. This ‘RAR code’ might function in regionalization and patterning of these two tissues by differentially modulating the expression of downstream effector genes during development.
Donald L J Quicke - One of the best experts on this subject based on the ideXlab platform.
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revision of the endemic new zealand braconid wasp genus metaspathius new subfamily placement and descriptions of four new species including three with fully winged females hymenoptera braconidae mesostoinae
New Zealand Entomologist, 2018Co-Authors: Donald L J Quicke, Sergey A Belokobylskij, Darren F Ward, Paul D N Hebert, Buntika A ButcherAbstract:The endemic New Zealand Cyclostome braconid wasp genus Metaspathius Brues, which was previously only known from a single specimen, an apterous female, is revised. Four new species, including three ...
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revision of the endemic new zealand braconid wasp genus metaspathius new subfamily placement and descriptions of four new species including three with fully winged females hymenoptera braconidae mesostoinae
New Zealand Entomologist, 2018Co-Authors: Donald L J Quicke, Sergey A Belokobylskij, Darren F Ward, Paul D N Hebert, Buntika A ButcherAbstract:ABSTRACTThe endemic New Zealand Cyclostome braconid wasp genus Metaspathius Brues, which was previously only known from a single specimen, an apterous female, is revised. Four new species, includin...
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systematics of the Cyclostome subfamilies of braconid parasitic wasps hymenoptera ichneumonoidea a simultaneous molecular and morphological bayesian approach
Molecular Phylogenetics and Evolution, 2006Co-Authors: Donald L J Quicke, Alejandro Zaldivarriveron, Miharu MoriAbstract:Abstract Phylogenetic relationships among 95 genera collectively representing 17 of the 18 currently recognized Cyclostome braconid wasp subfamilies were investigated based on DNA sequence fragments of the mitochondrial COI and the nuclear 28S rDNA genes, in addition to morphological data. The treatment of sequence length variation of the 28S partition was explored by either excluding ambiguously aligned regions and indel information (28SN) or recoding them (28SA) using the ‘fragment-level’ alignment method with a modified coding approach. Bayesian MCMC analyses were performed for the separate and combined data sets and a maximum parsimony analysis was also carried out for the simultaneous molecular and morphological data sets. There was a significant incongruence between the two genes and between 28S and morphology, but not for morphology and COI. Different analyses with the 28SA data matrix resulted in topologies that were generally similar to the ones from the 28SN matrix; however, the former topologies recovered a higher number of significantly supported clades and had a higher mean Bayesian posterior probability, thus supporting the inclusion of information from ambiguously aligned regions and indel events in phylogenetic analyses where possible. Based on the significantly supported clades obtained from the simultaneous molecular and morphological analyses, we propose that a total of 17 subfamilies should be recognized within the Cyclostome group. The subfamilial placements of several problematic Cyclostome genera were also established.
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cocoon silk chemistry of non Cyclostome braconidae with remarks on phylogenetic relationships within the microgastrinae hymenoptera braconidae
Journal of Natural History, 2004Co-Authors: Donald L J Quicke, Mark R Shaw, M Takahashi, B YanechinAbstract:Bulk amino acid composition was determined for cocoon silks for 54 species of non-Cyclostome braconid wasps collectively representing 14 subfamilies. Little intraspecific variation was encountered either between conspecific individuals of differing origin or between physically different silk layers within a single cocoon. Variation within subfamilies was small except in the Microgastrinae. Most taxa, excluding most microgastrines, had silk of a fairly typical fibroin type with high relative abundances of alanine, serine or glycine (of which either alanine or serine was the most abundant) and usually with moderately low molar concentrations of presumed acidic residues (aspartate/asparagine (As(x)) and glutamate/glutamine (Gl(x))) which ranged from approximately 2% up to nearly 30% (in Helconinae and Blacinae). In the Microgastrinae, members of the genus Microplitis (four species) were similar to the other non-Cyclostome subfamilies in having 14.3–26.1 molar % As(x), but the other 10 microgastrine genera in...
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ovipositor internal microsculpture in the braconidae insecta hymenoptera
Zoologica Scripta, 1998Co-Authors: Habibur M Rahman, Mike G Fitton, Donald L J QuickeAbstract:Variation in the microsculpture of the ovipositor egg canal, the morphology of the tip of the upper valve, the structure of the valvillus and the apex of the lower valve seals, as revealed by scanning electron microscopy is described for members of 52 genera representing 30 subfamilies of Braconidae. The possible phylogenetic implications of this variation are discussed. Characters supporting monophyly of the Cyclostome clade, and of the non-Cyclostome subfamilies Agathidinae, Pselaphaninae and Sigalphinae are reported. Functional and phylogenetic implications are discussed and possible convergent evolution of some features associated with endoparasitism are considered in the light of recent molecular systematics findings. © 1998 The Norwegian Academy of Science and Letters
Paul D Taylor - One of the best experts on this subject based on the ideXlab platform.
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disporella guada sp nov an erect ramose rectangulate Cyclostome bryozoa stenolaemata from the caribbean sea convergent evolution in bryozoan colony morphology
European journal of taxonomy, 2021Co-Authors: Paul D Taylor, Andrea Waeschenbach, Jeangeorges Harmelin, Claude BouchonAbstract:The taxonomy of Cyclostome bryozoans is founded on characters of the skeleton, but molecular sequence data have increasingly shown that established higher taxa are not monophyletic. Here we describe the skeletal morphology of a new species from Guadeloupe (French West Indies) with erect ramose colonies consisting of long, curved zooids that are typical of the suborder Cerioporina among living Cyclostomes. However, molecular evidence from nuclear ribosomal RNA genes 18S and 28S places the new taxon in the suborder Rectangulata, where this colony-form has not been previously recorded. It nests firmly within the genus Disporella Gray, 1848, in a strongly supported clade that also includes Plagioecia patina (Lamarck, 1816) (Tubuliporina) and the sister taxa Doliocoitis cyanea Gordon & Taylor, 2001 (Rectangulata) and Favosipora rosea Gordon & Taylor, 2001 (Cerioporina). The short and robust branches of the new Guadeloupe Cyclostome, here named Disporella guada Harmelin, Taylor & Waeschenbach sp. nov., are well adapted to life in shallow rocky sites exposed to severe wave action, which appear to be its exclusive habitat.
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evolution of larval size in Cyclostome bryozoans
Historical Biology, 2018Co-Authors: Paul D Taylor, Helen L. JenkinsAbstract:Cyclostomes are the only order of stenolaemate bryozoans living today. The non-feeding larvae of modern Cyclostomes metamorphose on settlement to produce a calcified dome-shaped protoecium. Protoec...
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a new cenozoic Cyclostome bryozoan genus from argentina and new zealand strengthening the biogeographical links between south america and australasia
Alcheringa, 2018Co-Authors: Paul D Taylor, Soledad Silvana BrezinaAbstract:Taylor, P.D. & Brezina, S., February 2018. A new Cenozoic Cyclostome bryozoan genus from Argentina and New Zealand: strengthening the biogeographical links between South America and Australasia. Al...
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ancestrular morphology in Cyclostome bryozoans and the quest for phylogenetically informative skeletal characters
Journal of Natural History, 2017Co-Authors: Helen L. Jenkins, Paul D TaylorAbstract:ABSTRACTCyclostomes are an ancient order of bryozoans with more than 500 living species. Traditionally, Cyclostome taxonomy has depended almost entirely on characters of the calcareous skeletons of mature colonies. However, the taxonomic distribution of these characters is largely incongruent with well-supported molecular phylogenetic trees, implying the need for major revisions if Cyclostome taxonomy is to reflect phylogeny. While far more taxa must be sequenced to ascertain their molecular relationships, there is also a need to discover morphological characters that can be used to support molecular clades, not least to allow these clades to be inferred among fossil Cyclostomes for which molecular data will never be available. Here we survey the skeletal morphology of the first-formed part of the skeleton – the protoecium of the founding zooid (ancestrula) – in a variety of Recent and well-preserved fossil Cyclostomes, motivated by the recent discovery of a morphologically disparate molecular clade that ...
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Ancestrular morphology in Cyclostome bryozoans and the quest for phylogenetically informative skeletal characters
2017Co-Authors: Helen L. Jenkins, Paul D TaylorAbstract:Cyclostomes are an ancient order of bryozoans with more than 500 living species. Traditionally, Cyclostome taxonomy has depended almost entirely on characters of the calcareous skeletons of mature colonies. However, the taxonomic distribution of these characters is largely incongruent with well-supported molecular phylogenetic trees, implying the need for major revisions if Cyclostome taxonomy is to reflect phylogeny. While far more taxa must be sequenced to ascertain their molecular relationships, there is also a need to discover morphological characters that can be used to support molecular clades, not least to allow these clades to be inferred among fossil Cyclostomes for which molecular data will never be available. Here we survey the skeletal morphology of the first-formed part of the skeleton – the protoecium of the founding zooid (ancestrula) – in a variety of Recent and well-preserved fossil Cyclostomes, motivated by the recent discovery of a morphologically disparate molecular clade that can be distinguished by protoecial characters. The distribution of pseudopores on the protoecium is shown to vary between species, with eight patterns recognizable, offering a new source of skeletal characters in both living and fossil taxa. However, the patterns seem not to be fully congruent with the Cyclostome molecular tree and more data and analyses are required before these patterns can be used to recognize Cyclostome clades.
David Jandzik - One of the best experts on this subject based on the ideXlab platform.
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evolution of retinoic acid receptors in chordates insights from three lamprey species lampetra fluviatilis petromyzon marinus and lethenteron japonicum
Evodevo, 2015Co-Authors: Florent Campopaysaa, David Jandzik, Yoko Takioogawa, Maria V Cattell, Haley C Neef, James A Langeland, Shigeru KurataniAbstract:Background Retinoic acid (RA) signaling controls many developmental processes in chordates, from early axis specification to late organogenesis. The functions of RA are chiefly mediated by a subfamily of nuclear hormone receptors, the retinoic acid receptors (RARs), that act as ligand-activated transcription factors. While RARs have been extensively studied in jawed vertebrates (that is, gnathostomes) and invertebrate chordates, very little is known about the repertoire and developmental roles of RARs in Cyclostomes, which are extant jawless vertebrates. Here, we present the first extensive study of Cyclostome RARs focusing on three different lamprey species: the European freshwater lamprey, Lampetra fluviatilis, the sea lamprey, Petromyzon marinus, and the Japanese lamprey, Lethenteron japonicum.
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Evolution of retinoic acid receptors in chordates: insights from three lamprey species, Lampetra fluviatilis, Petromyzon marinus, and Lethenteron japonicum
EvoDevo, 2015Co-Authors: Florent Campo-paysaa, David Jandzik, Maria V Cattell, Haley C Neef, James A Langeland, Shigeru Kuratani, Yoko Takio-ogawa, Daniel M Medeiros, Sylvie Mazan, Shigehiro KurakuAbstract:Background : Retinoic acid (RA) signaling controls many developmental processes in chordates, from early axis specification to late organogenesis. The functions of RA are chiefly mediated by a subfamily of nuclear hormone receptors, the retinoic acid receptors (RARs), that act as ligand-activated transcription factors. While RARs have been extensively studied in jawed vertebrates (that is, gnathostomes) and invertebrate chordates, very little is known about the repertoire and developmental roles of RARs in Cyclostomes, which are extant jawless vertebrates. Here, we present the first extensive study of Cyclostome RARs focusing on three different lamprey species: the European freshwater lamprey, Lampetra fluviatilis, the sea lamprey, Petromyzon marinus, and the Japanese lamprey, Lethenteron japonicum. Results : We identified four rar paralogs (rar1, rar2, rar3, and rar4) in each of the three lamprey species, and phylogenetic analyses indicate a complex evolutionary history of lamprey rar genes including the origin of rar1 and rar4 by lineage-specific duplication after the lamprey-hagfish split. We further assessed their expression patterns during embryonic development by in situ hybridization. The results show that lamprey rar genes are generally characterized by dynamic and highly specific expression domains in different embryonic tissues. In particular, lamprey rar genes exhibit combinatorial expression domains in the anterior central nervous system (CNS) and the pharyngeal region. Conclusions : Our results indicate that the genome of lampreys encodes at least four rar genes and suggest that the lamprey rar complement arose from vertebrate-specific whole genome duplications followed by a lamprey-specific duplication event. Moreover, we describe a combinatorial code of lamprey rar expression in both anterior CNS and pharynx resulting from dynamic and highly specific expression patterns during embryonic development. This ‘RAR code’ might function in regionalization and patterning of these two tissues by differentially modulating the expression of downstream effector genes during development.
