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Ralf Janssen - One of the best experts on this subject based on the ideXlab platform.
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Developmental abnormalities in Glomeris marginata (Villers 1789) (Myriapoda: Diplopoda): implications for body axis determination in a myriapod
Naturwissenschaften, 2013Co-Authors: Ralf JanssenAbstract:Abnormally developing embryos (ADEs) of the common pill millipede Glomeris marginata have been investigated by means of nuclear staining and mRNA in situ hybridization. It showed that all ADEs represent cases of Duplicitas posterior , which means that the posterior body pole is duplicated. The severity of the duplication ranges from duplicated posterior trunk segments in one specimen to an almost completely duplicated specimen that only shares the very anterior head region. Remarkably, none of the encountered ADEs represents a case of Duplicitas anterior (duplicated anterior pole) or a case of Duplicitas cruciata (cruciate duplication with two anterior and two posterior poles). This observation is discussed in the light of earlier reports on G . marginata ADEs that claim to have found these abnormalities. The lack of any other axial abnormality aside from D . posterior implies that early axis determination in G . marginata , and possibly myriapods in general, underlies the developmental mechanisms that prevent the formation of any other type of axial duplication. It is proposed that the formation of D . posterior -type embryos could be caused by the formation of two instead of only one posterior cumulus early during development.
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Segment polarity gene expression in a myriapod reveals conserved and diverged aspects of early head patterning in arthropods
Development Genes and Evolution, 2012Co-Authors: Ralf JanssenAbstract:Arthropods show two kinds of developmental mode. In the so-called long germ developmental mode (as exemplified by the fly Drosophila ), all segments are formed almost simultaneously from a preexisting field of cells. In contrast, in the so-called short germ developmental mode (as exemplified by the vast majority of arthropods), only the anterior segments are patterned similarly as in Drosophila , and posterior segments are added in a single or double segmental periodicity from a posterior segment addition zone (SAZ). The addition of segments from the SAZ is controlled by dynamic waves of gene activity. Recent studies on a spider have revealed that a similar dynamic process, involving expression of the segment polarity gene (SPG) hedgehog ( hh ), is involved in the formation of the anterior head segments. The present study shows that in the myriapod Glomeris marginata the early expression of hh is also in a broad anterior domain, but this domain corresponds only to the ocular and antennal segment. It does not, like in spiders, represent expression in the posterior adjacent segment. In contrast, the anterior hh pattern is conserved in Glomeris and insects. All investigated myriapod SPGs and associated factors are expressed with delay in the premandibular (tritocerebral) segment. This delay is exclusively found in insects and myriapods, but not in chelicerates, crustaceans and onychophorans. Therefore, it may represent a synapomorphy uniting insects and myriapods (Atelocerata hypothesis), contradicting the leading opinion that suggests a sister relationship of crustaceans and insects (Pancrustacea hypothesis). In Glomeris embryos, the SPG engrailed is first expressed in the mandibular segment. This feature is conserved in representatives of all arthropod classes suggesting that the mandibular segment may have a special function in anterior patterning.
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Gene expression suggests conserved aspects of Hox gene regulation in arthropods and provides additional support for monophyletic Myriapoda
EvoDevo, 2010Co-Authors: Ralf Janssen, Graham E. BuddAbstract:Antisense transcripts of Ultrabithorax (aUbx) in the millipede Glomeris and the centipede Lithobius are expressed in patterns complementary to that of the Ubx sense transcripts. A similar complementary expression pattern has been described for non-coding RNAs (ncRNAs) of the bithoraxoid (bxd) locus in Drosophila, in which the transcription of bxd ncRNAs represses Ubx via transcriptional interference. We discuss our findings in the context of possibly conserved mechanisms of Ubx regulation in myriapods and the fly. Bicistronic transcription of Ubx and Antennapedia (Antp) has been reported previously for a myriapod and a number of crustaceans. In this paper, we show that Ubx/Antp bicistronic transcripts also occur in Glomeris and an onychophoran, suggesting further conserved mechanisms of Hox gene regulation in arthropods. Myriapod monophyly is supported by the expression of aUbx in all investigated myriapods, whereas in other arthropod classes, including the Onychophora, aUbx is not expressed. Of the two splice variants of Ubx/Antp only one could be isolated from myriapods, representing a possible further synapomorphy of the Myriapoda.
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Dorso-ventral differences in gene expression in Glomeris marginata Villers, 1789 (Myriapoda: Diplopoda)
Norwegian journal of entomology, 2006Co-Authors: Ralf Janssen, Nicola-michael Prpic, Wim G.m. DamenAbstract:Dorso-ventral differences in gene expression in Glomeris marginata Villers, 1789 (Myriapoda: Diplopoda)
Gregory D. Edgecombe - One of the best experts on this subject based on the ideXlab platform.
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Phylogenomics illuminates the backbone of the Myriapoda Tree of Life and reconciles morphological and molecular phylogenies
Scientific reports, 2018Co-Authors: Rosa Fernández, Gregory D. Edgecombe, Gonzalo GiribetAbstract:The interrelationships of the four classes of Myriapoda have been an unresolved question in arthropod phylogenetics and an example of conflict between morphology and molecules. Morphology and development provide compelling support for Diplopoda (millipedes) and Pauropoda being closest relatives, and moderate support for Symphyla being more closely related to the diplopod-pauropod group than any of them are to Chilopoda (centipedes). In contrast, several molecular datasets have contradicted the Diplopoda-Pauropoda grouping (named Dignatha), often recovering a Symphyla-Pauropoda group (named Edafopoda). Here we present the first transcriptomic data including a pauropod and both families of symphylans, allowing myriapod interrelationships to be inferred from phylogenomic data from representatives of all main lineages. Phylogenomic analyses consistently recovered Dignatha with strong support. Taxon removal experiments identified outgroup choice as a critical factor affecting myriapod interrelationships. Diversification of millipedes in the Ordovician and centipedes in the Silurian closely approximates fossil evidence whereas the deeper nodes of the myriapod tree date to various depths in the Cambrian-Early Ordovician, roughly coinciding with recent estimates of terrestrialisation in other arthropod lineages, including hexapods and arachnids.
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Phylogenomics illuminates the backbone of the Myriapoda Tree of Life and reconciles morphological and molecular phylogenies
2017Co-Authors: Rosa Fernández, Gregory D. Edgecombe, Gonzalo GiribetAbstract:The interrelationships of the four classes of Myriapoda have been an unresolved question in arthropod phylogenetics and an example of conflict between morphology and molecules. Morphology and development provide compelling support for Diplopoda (millipedes) and Pauropoda being closest relatives, and moderate support for Symphyla being more closely related to the diplopod-pauropod group than any of them are to Chilopoda (centipedes). In contrast, several molecular datasets have contradicted the Diplopoda-Pauropoda grouping (named Dignatha). Here we present the first transcriptomic data including a pauropod and both families of symphylans, allowing myriapod interrelationships to be inferred from phylogenomic data from representatives of all main lineages. Phylogenomic analyses consistently recovered Dignatha with strong support. Taxon removal experiments identified outgroup choice as a critical factor affecting myriapod interrelationships. Diversification of millipedes in the Ordovician and centipedes in the Silurian closely approximates fossil evidence whereas the deeper nodes of the myriapod tree date to various depths in the Cambrian-Early Ordovician, roughly coinciding with recent estimates of terrestrialisation in other arthropod lineages, including hexapods and arachnids. We provide a summary state-of-the-art Myriapoda Tree of Life at the ordinal level, the resolution of which has been improved by phylogenomics.
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Exploring Phylogenetic Relationships within Myriapoda and the Effects of Matrix Composition and Occupancy on Phylogenomic Reconstruction.
Systematic biology, 2016Co-Authors: Rosa Fernández, Gregory D. Edgecombe, Gonzalo GiribetAbstract:Myriapods, including the diverse and familiar centipedes and millipedes, are one of the dominant terrestrial arthropod groups. Although molecular evidence has shown that Myriapoda is monophyletic, its internal phylogeny remains contentious and understudied, especially when compared to those of Chelicerata and Hexapoda. Until now, efforts have focused on taxon sampling (e.g., by including a handful of genes from many species) or on maximizing matrix size (e.g., by including hundreds or thousands of genes in just a few species), but a phylogeny maximizing sampling at both levels remains elusive. In this study, we analyzed 40 Illumina transcriptomes representing 3 of the 4 myriapod classes (Diplopoda, Chilopoda, and Symphyla); 25 transcriptomes were newly sequenced to maximize representation at the ordinal level in Diplopoda and at the family level in Chilopoda. Ten supermatrices were constructed to explore the effect of several potential phylogenetic biases (e.g., rate of evolution, heterotachy) at 3 levels of gene occupancy per taxon (50%, 75%, and 90%). Analyses based on maximum likelihood and Bayesian mixture models retrieved monophyly of each myriapod class, and resulted in 2 alternative phylogenetic positions for Symphyla, as sister group to Diplopoda + Chilopoda, or closer to Diplopoda, the latter hypothesis having been traditionally supported by morphology. Within centipedes, all orders were well supported, but 2 deep nodes remained in conflict in the different analyses despite dense taxon sampling at the family level. Relationships among centipede orders in all analyses conducted with the most complete matrix (90% occupancy) are at odds not only with the sparser but more gene-rich supermatrices (75% and 50% supermatrices) and with the matrices optimizing phylogenetic informativeness or most conserved genes, but also with previous hypotheses based on morphology, development, or other molecular data sets. Our results indicate that a high percentage of ribosomal proteins in the most complete matrices, in conjunction with distance from the root, can act in concert to compromise the estimated relationships within the ingroup. We discuss the implications of these findings in the context of the ever more prevalent quest for completeness in phylogenomic studies.
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Exploring phylogenomic relationships within Myriapoda: should high matrix occupancy be the goal?
2015Co-Authors: Rosa Fernández, Gregory D. Edgecombe, Gonzalo GiribetAbstract:Myriapods are one of the dominant terrestrial arthropod groups including the diverse and familiar centipedes and millipedes. Although molecular evidence has shown that Myriapoda is monophyletic, its internal phylogeny remains contentious and understudied, especially when compared to those of Chelicerata and Hexapoda. Until now, efforts have focused on taxon sampling (e.g., by including a handful of genes in many species) or on maximizing matrix occupancy (e.g., by including hundreds or thousands of genes in just a few species), but a phylogeny maximizing sampling at both levels remains elusive. In this study, we analyzed forty Illumina transcriptomes representing three myriapod classes (Diplopoda, Chilopoda and Symphyla); twenty-five transcriptomes were newly sequenced to maximize representation at the ordinal level in Diplopoda and at the family level in Chilopoda. Eight supermatrices were constructed to explore the effect of several potential phylogenetic biases (e.g., rate of evolution, heterotachy) at three levels of mean gene occupancy per taxon (50%, 75% and 90%). Analyses based on maximum likelihood and Bayesian mixture models retrieved monophyly of each myriapod class, and resulted in two alternative phylogenetic positions for Symphyla, as sister group to Diplopoda + Chilopoda, or closer to Diplopoda, the latter hypothesis having been traditionally supported by morphology. Within centipedes, all orders were well supported, but two nodes remained in conflict in the different analyses despite dense taxon sampling at the family level, situating the order Scolopendromorpha as sister group to a morphologically-anomalous grouping of Lithobiomorpha + Geophilomorpha in a subset of analyses. Interestingly, this anomalous result was obtained for all analyses conducted with the most complete matrix (90% of occupancy), being at odds not only with the sparser but more gene-rich supermatrices (75% and 50% supermatrices) or with the matrices optimizing phylogenegic informativeness and the most conserved genes, but also with previous hypotheses based on morphology, development or other molecular data sets. We discuss the implications of these findings in the context of the ever more prevalent quest for completeness in phylogenomic studies.
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a congruent solution to arthropod phylogeny phylogenomics micrornas and morphology support monophyletic mandibulata
Proceedings of The Royal Society B: Biological Sciences, 2011Co-Authors: Gregory D. Edgecombe, Omar Rotastabelli, Lahcen I Campbell, Henner Brinkmann, Stuart J Longhorn, Kevin J Peterson, Davide Pisani, Herve Philippe, Maximilian J. TelfordAbstract:While a unique origin of the euarthropods is well established, relationships between the four euarthropod classes—chelicerates, myriapods, crustaceans and hexapods—are less clear. Unsolved questions include the position of myriapods, the monophyletic origin of chelicerates, and the validity of the close relationship of euarthropods to tardigrades and onychophorans. Morphology predicts that myriapods, insects and crustaceans form a monophyletic group, the Mandibulata, which has been contradicted by many molecular studies that support an alternative Myriochelata hypothesis (Myriapoda plus Chelicerata). Because of the conflicting insights from published molecular datasets, evidence from nuclear-coding genes needs corroboration from independent data to define the relationships among major nodes in the euarthropod tree. Here, we address this issue by analysing two independent molecular datasets: a phylogenomic dataset of 198 protein-coding genes including new sequences for myriapods, and novel microRNA complements sampled from all major arthropod lineages. Our phylogenomic analyses strongly support Mandibulata, and show that Myriochelata is a tree-reconstruction artefact caused by saturation and long-branch attraction. The analysis of the microRNA dataset corroborates the Mandibulata, showing that the microRNAs miR-965 and miR-282 are present and expressed in all mandibulate species sampled, but not in the chelicerates. Mandibulata is further supported by the phylogenetic analysis of a comprehensive morphological dataset covering living and fossil arthropods, and including recently proposed, putative apomorphies of Myriochelata. Our phylogenomic analyses also provide strong support for the inclusion of pycnogonids in a monophyletic Chelicerata, a paraphyletic Cycloneuralia, and a common origin of Arthropoda (tardigrades, onychophorans and arthropods), suggesting that previous phylogenies grouping tardigrades and nematodes may also have been subject to tree-reconstruction artefacts.
Gerasimos Cassis - One of the best experts on this subject based on the ideXlab platform.
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Arthropod Cladistics: Combined Analysis of Histone H3 and U2 snRNA Sequences and Morphology
Cladistics, 2000Co-Authors: Gregory D. Edgecombe, George D. F. Wilson, Donald J. Colgan, Michael R. Gray, Gerasimos CassisAbstract:Morphological, developmental, ultrastructural, and gene order characters are catalogued for the same set of arthropod terminals as we have scored in a recent study of histone H3 and U2 snRNA sequences (D. J. Colgan et al., 1998, Aust. J. Zool. 46, 419–437). We examine the implications of separate and simultaneous analyses of sequence and non-sequence data for arthropod relationships. The most parsimonious trees based on 211 non-sequence characters (273 apomorphic states) support traditional higher taxa as clades, including Mandibulata, Crustacea, Atelocerata, Myriapoda, and Hexapoda. Combined analysis of morphology with histone H3 and U2 sequences with equal character weights differs from the morphological results alone in supporting Progoneata + Hexapoda (= Labiophora) in favor of a monophyletic Myriapoda, resolves the entognathous hexapods as a grade, and supports pycnogonids as sister group to Euchelicerata (rather than as basal euarthropods). Monophyly of Chelicerata (including pycnogonids), Mandibulata, Crustacea, Progoneata, Chilopoda, and Hexapoda is maintained under a range of transition/transversion and third codon weights, whereas Atelocerata and Myriapoda/Labiophora do not withstand all sensitivity analyses.
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Regular ArticleArthropod Cladistics: Combined Analysis of Histone H3 and U2 snRNA Sequences and Morphology☆
Cladistics, 2000Co-Authors: Gregory D. Edgecombe, George D. F. Wilson, Donald J. Colgan, Michael R. Gray, Gerasimos CassisAbstract:Morphological, developmental, ultrastructural, and gene order characters are catalogued for the same set of arthropod terminals as we have scored in a recent study of histone H3 and U2 snRNA sequences (D. J. Colgan et al., 1998, Aust. J. Zool. 46, 419–437). We examine the implications of separate and simultaneous analyses of sequence and non-sequence data for arthropod relationships. The most parsimonious trees based on 211 non-sequence characters (273 apomorphic states) support traditional higher taxa as clades, including Mandibulata, Crustacea, Atelocerata, Myriapoda, and Hexapoda. Combined analysis of morphology with histone H3 and U2 sequences with equal character weights differs from the morphological results alone in supporting Progoneata + Hexapoda (= Labiophora) in favor of a monophyletic Myriapoda, resolves the entognathous hexapods as a grade, and supports pycnogonids as sister group to Euchelicerata (rather than as basal euarthropods). Monophyly of Chelicerata (including pycnogonids), Mandibulata, Crustacea, Progoneata, Chilopoda, and Hexapoda is maintained under a range of transition/transversion and third codon weights, whereas Atelocerata and Myriapoda/Labiophora do not withstand all sensitivity analyses.
Thomas Wesener - One of the best experts on this subject based on the ideXlab platform.
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The Myriapoda of Halimun-Salak National Park (Java, Indonesia): overview and faunal composition.
Biodiversity data journal, 2019Co-Authors: Michael Hilgert, Nesrine Akkari, Cahyo Rahmadi, Thomas WesenerAbstract:The myriapod fauna of the mega-diverse country of Indonesia is so far insufficiently known, with no species lists or determination keys. In order to obtain an overview of the faunal composition of the Myriapoda in an Indonesian forest system, the fauna of the Halimun-Salak National Park in western Java was explored during the dry season (September-October 2015) in the framework of the German-Indonesian INDOBIOSYS project (Indonesian Biodiversity Discovery and Information System). A total of 980 Myriapoda specimens were collected by hand by 3-4 researchers from three different sites in the national park, from which 796 specimens were determined to a higher taxonomic level (class, order, family) and 617 specimens were determined to morphospecies. Among these, 27 were Symphyla (4%) (excluded from further analyses), 226 Chilopoda (28%) and 543 Diplopoda (68%). The Scolopendromorpha (64% of all identified centipedes) and Polydesmida (69% of all identified Diplopoda) were the most represented orders in our samples. Twenty-four morphospecies of Chilopoda were determined: one each of Scutigeromorpha and Lithobiomorpha, six Scolopendromorpha and sixteen Geophilomorpha. Nine orders of diplopods were present, with a total of 47 morphospecies: one each of Polyxenida, Glomeridesmida and Chordeumatida, two each of Glomerida, Spirobolida and Siphonophorida, seven of Sphaerotheriida, ten of Spirostreptida and 21 of Polydesmida. Two species curves were obtained to have a first idea about the myriapod diversity in the Halimun-Salak National Park and to compare the three individual collecting sites. Our results depict the Scolopendromorpha as the most common centipedes in Javanese rainforests and the Geophilomorpha as the most species-rich order. In contrast, the Polydesmida were the most dominant millipede group with 167 specimens and with 13 morphospecies the family Paradoxosomatidae was the most diverse.
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an apparently non swinging tentorium in the diplopoda Myriapoda comparative morphology of the tentorial complex in giant pill millipedes sphaerotheriida
ZooKeys, 2018Co-Authors: Leif Moritz, Thomas Wesener, Markus KochAbstract:The presence of a swinging tentorium is a key apomorphy of Myriapoda, but this character has been studied in detail in only few species. Here the tentorium, i.e., the peristomatic skeleton of the preoral chamber, is comparatively studied in three species of the millipede order Sphaerotheriida Brandt, 1833. Since dissections of the fragile tentorial components proved to be difficult, despite the large head size, they were analysed mainly in situ via micro-computed tomography. Our results confirm previous observations of large differences in the tentorial construction in the giant pill-millipedes compared to chilognathan diplopods. The tentorium of Sphaerotheriida consists of a curved, plate-like epipharyngeal bar with distal projections, an elongate and thin hypopharyngeal bar, and a plate-like triangular posterior process; a transverse bar is absent. Only seven muscles attach at the tentorium in giant pill-millipedes, including two antennal muscles and two muscles of the gnathochilarium. Within the order Sphaerotheriida, the composition of the tentorium and its muscular equipment seems to be conserved, except for some variability in the shape of the epipharyngeal bar. As the transverse bar has been considered essential for the mobility of the tentorium in myriapods, its absence in Sphaerotheriida may indicate that their tentorium is not capable of performing a swing. Loss of tentorial mobility may also pertain to the order Glomerida Brandt, 1833, inferred here from the absence of a posterior process. An apparently immobile tentorium in Glomerida and Sphaerotheriida can straightforwardly be correlated with transformations of the head related to their ability of volvation. The different transformations of the tentorium, here hypothesised to cause immobility, may support current assumptions that the ability of volvation evolved convergently in Glomerida and Sphaerotheriida. This conclusion, however, still requires more detailed studies of the head anatomy in Glomerida and Glomeridesmida Cook, 1895.
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Symphylella patrickmuelleri sp. nov. (Myriapoda: Symphyla): The oldest known Symphyla and first fossil record of Scolopendrellidae from Cretaceous Burmese amber
Cretaceous Research, 2018Co-Authors: Leif Moritz, Thomas WesenerAbstract:Abstract Symphyla are one of the least known of the four classes of the Myriapoda. While Symphyla are dated to have split from the other myriapods at about 430–593 Ma, there are no fossil specimens known aside from seven specimens of the family Scutigerellidae preserved in Dominican and Baltic amber, with a maximum age of ca. 54 Ma. Here we describe the first fossil representative of the second Symphyla family, the Scolopendrellidae, Symphylella patrickmuelleri sp. nov., from Burmese amber (ca. 99 Ma). Utilizing micro-computed tomography (μCT) technology, as well as light microscopy and multi-layer photography, our specimen, despite being juvenile, can be assigned to the genus Symphylella Silvestri, 1902, a species-rich Recent genus that has an almost worldwide distribution. The specimen is preserved after ejecting long threads of silk from its large spinnerets. Our findings show that the recent genera and families of the Symphyla diverged already before the end of the Mesozoic.
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First results of the German Barcode of Life (GBOL) - Myriapoda project: Cryptic lineages in German Stenotaenialinearis (Koch, 1835) (Chilopoda, Geophilomorpha).
ZooKeys, 2015Co-Authors: Thomas Wesener, Peter Decker, Jörg Spelda, Karin Voigtländer, Jan Philip Oeyen, Norman LindnerAbstract:As part of the German Barcode of Life (GBOL) Myriapoda program, which aims to sequence the COI barcoding fragment for 2000 specimens of Germany's 200 myriapod species in the near future, 44 sequences of the centipede order Geophilomorpha are analyzed. The analyses are limited to the genera Geophilus Leach, 1814 and Stenotaenia Koch, 1847 and include a total of six species. A special focus is Stenotaenia, of which 19 specimens from southern, western and eastern Germany could be successfully sequenced. The Stenotaenia data shows the presence of three to four vastly different (13.7-16.7% p-distance) lineages of the genus in Germany. At least two of the three lineages show a wide distribution across Germany, only the lineage including topotypes of Stenotaenialinearis shows a more restricted distribution in southern Germany. In a maximum likelihood phylogenetic analysis the Italian species Stenotaenia 'sorrentina' (Attems, 1903) groups with the different German Stenotaenialinearis clades. The strongly different Stenotaenialinearis lineages within Germany, independent of geography, are a strong hint for the presence of additional, cryptic Stenotaenia species in Germany.
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Sternites and spiracles – The unclear homology of ventral sclerites in the basal millipede order Glomeridesmida (Myriapoda, Diplopoda)
Arthropod Structure & Development, 2013Co-Authors: Thomas Wesener, Petra Sierwald, Johann-wolfgang WägeleAbstract:Abstract We report the discovery of a ventral plate in the basal and little-known chilognath millipede order Glomeridesmida. This ventral plate, interpreted here as a ‘true sternite’, is clearly separate from both the coxa and the more lateral stigma-carrying plates commonly referred to as ‘diplopod sternites’. Therefore, the lateral, stigma-carrying plates of the Diplopoda, previously referred to as sternites, are not sternal elements, but subcoxal elements associated with the limb base. This discovery changes the nomenclature used for the ventral plates in Diplopoda, with the formerly named ‘sternite’ better referred to as ‘stigma-carrying plate’. In helminthomorph Diplopoda, the stigma-carrying plates are apparently secondarily fused with the sternite. The main argument for the independent evolution of tracheae in insects and myriapods, the different location of their respective spiracles, no longer holds true. In all Myriapoda and Hexapoda the spiracles associated with subcoxal elements are located lateral to the limb base. This discovery shows that the arguments for an independent origin of tracheae in insects and myriapods are not uncontestable.
Thorsten Burmester - One of the best experts on this subject based on the ideXlab platform.
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Diversity, evolution, and function of myriapod hemocyanins
BMC Evolutionary Biology, 2018Co-Authors: Samantha Scherbaum, Nadja Hellmann, Rosa Fernández, Christian Pick, Thorsten BurmesterAbstract:Background Hemocyanin transports O_2 in the hemolymph of many arthropod species. Such respiratory proteins have long been considered unnecessary in Myriapoda. As a result, the presence of hemocyanin in Myriapoda has long been overlooked. We analyzed transcriptome and genome sequences from all major myriapod taxa – Chilopoda, Diplopoda, Symphyla, and Pauropoda – with the aim of identifying hemocyanin-like proteins. Results We investigated the genomes and transcriptomes of 56 myriapod species and identified 46 novel full-length hemocyanin subunit sequences in 20 species of Chilopoda, Diplopoda, and Symphyla, but not Pauropoda. We found in Cleidogona sp. (Diplopoda, Chordeumatida) a hemocyanin-like sequence with mutated copper-binding centers, which cannot bind O_2. An RNA-seq approach showed markedly different hemocyanin mRNA levels from ~ 6 to 25,000 reads per kilobase per million reads. To evaluate the contribution of hemocyanin to O_2 transport, we specifically studied the hemocyanin of the centipede Scolopendra dehaani. This species harbors two distinct hemocyanin subunits with low expression levels. We showed cooperative O_2 binding in the S. dehaani hemolymph, indicating that hemocyanin supports O_2 transport even at low concentration. Further, we demonstrated that hemocyanin is > 1500-fold more highly expressed in the fertilized egg than in the adult. Conclusion Hemocyanin was most likely the respiratory protein in the myriapod stem-lineage, but multiple taxa may have independently lost hemocyanin and thus the ability of efficient O_2 transport. In myriapods, hemocyanin is much more widespread than initially appreciated. Some myriapods express hemocyanin only at low levels, which are, nevertheless, sufficient for O_2 supply. Notably, also in myriapods, a non-respiratory protein similar to insect storage hexamerins evolved from the hemocyanin.
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Phylogenetic position of Myriapoda revealed by 454 transcriptome sequencing
Molecular phylogenetics and evolution, 2014Co-Authors: Peter Rehm, Karen Meusemann, Janus Borner, Bernhard Misof, Thorsten BurmesterAbstract:Abstract Myriapods had been considered closely allied to hexapods (insects and relatives). However, analyses of molecular sequence data have consistently placed Myriapoda either as a sister group of Pancrustacea, comprising crustaceans and hexapods, and thereby supporting the monophyly of Mandibulata, or retrieved Myriapoda as a sister group of Chelicerata (spiders, ticks, mites and allies). In addition, the relationships among the four myriapod groups (Pauropoda, Symphyla, Diplopoda, Chilopoda) are unclear. To resolve the phylogeny of myriapods and their relationship to other main arthropod groups, we collected transcriptome data from the symphylan Symphylella vulgaris, the centipedes Lithobius forficatus and Scolopendra dehaani, and the millipedes Polyxenus lagurus, Glomeris pustulata and Polydesmus angustus by 454 sequencing. We concatenated a multiple sequence alignment that contained 1550 orthologous single copy genes (1,109,847 amino acid positions) from 55 euarthropod and 14 outgroup taxa. The final selected alignment included 181 genes and 37,425 amino acid positions from 55 taxa, with eight myriapods and 33 other euarthropods. Bayesian analyses robustly recovered monophyletic Mandibulata, Pancrustacea and Myriapoda. Most analyses support a sister group relationship of Symphyla in respect to a clade comprising Chilopoda and Diplopoda. Inclusion of additional sequence data from nine myriapod species resulted in an alignment with poor data density, but broader taxon average. With this dataset we inferred Diplopoda + Pauropoda as closest relatives (i.e., Dignatha) and recovered monophyletic Helminthomorpha. Molecular clock calculations suggest an early Cambrian emergence of Myriapoda ∼513 million years ago and a late Cambrian divergence of myriapod classes. This implies a marine origin of the myriapods and independent terrestrialization events during myriapod evolution.
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Diplopod Hemocyanin Sequence and the Phylogenetic Position of the Myriapoda
Molecular biology and evolution, 2001Co-Authors: Kristina Kusche, Thorsten BurmesterAbstract:Hemocyanins are copper-containing respiratory proteins of the Arthropoda that have so far been thoroughly investigated only in the Chelicerata and the Crustacea but have remained unstudied until now in the Myriapoda. Here we report the first sequence of a myriapod hemocyanin. The hemocyanin of Spirostreptus sp. (Diplopoda: Spirostreptidae) is composed of two distinct subunits that are arranged in a 6 x 6 native molecule. The cloned hemocyanin subunit cDNA codes of for a polypeptide of 653 amino acids (75.5 kDa) that includes a signal peptide of 18 amino acids. The sequence closely resembles that of the chelicerate hemocyanins. Molecular phylogenetic analyses reject with high statistical confidence the integrity of the Tracheata (i.e., Myriapoda + Insecta) but give conflicting results on the position of the myriapod hemocyanin. While distance matrix and maximum-likelihood methods support a basal position of the Spirostreptus hemocyanin with respect to the other hemocyanins, parsimony analysis suggests a sister group relationship with the chelicerate hemocyanins. The latter topology is also supported by a unique shared deletion of an alpha-helix. A common ancestry of Myriapoda and Chelicerata should be seriously considered.
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Identification, structure, and properties of hemocyanins from Diplopod Myriapoda.
The Journal of biological chemistry, 1999Co-Authors: Elmar Jaenicke, Heinz Decker, Wolfgang Gebauer, Jürgen Markl, Thorsten BurmesterAbstract:Abstract Hemocyanins are copper-containing, respiratory proteins that occur in the hemolymph of many arthropod species. Here we report for the first time the presence of hemocyanins in the diplopod Myriapoda, demonstrating that these proteins are more widespread among the Arthropoda than previously thought. The hemocyanin ofSpirostreptus sp. (Diplopoda: Spirostreptidae) is composed of two immunologically distinct subunits in the 75-kDa range that are most likely arranged in a 36-mer (6 × 6) native molecule. It has a high oxygen affinity (P 50 = 4.7 torr) but low cooperativity (h = 1.3 ± 0.2).Spirostreptus hemocyanin is structurally similar to the single known hemocyanin from the myriapod taxon, Scutigera coleoptrata (Chilopoda), indicating a rather conservative architecture of the myriapod hemocyanins. Western blotting demonstrates shared epitopes of Spirostreptus hemocyanin with both chelicerate and crustacean hemocyanins, confirming its identity as an arthropod hemocyanin.
