Ventral Nerve Cord

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Ian Orchard - One of the best experts on this subject based on the ideXlab platform.

  • immunohistochemical localization of tyrosine hydroxylase in the Ventral Nerve Cord of the stick insect carausius morosus including neurons innervating the salivary glands
    Cell and Tissue Research, 1996
    Co-Authors: Ian Orchard
    Abstract:

    The distribution of tyrosine hydroxylase-like immunoreactive neurons is mapped in the Ventral Nerve Cord of the stick insect, Carausius morosus. This study also examines the tyrosine hydroxylase- and serotonin-like immunoreactive elements in the salivary glands of Carausius morosus. Tyrosine hydroxylase is the first and rate-limiting enzyme in the pathway for the production of catecholamines; therefore, tyrosine hydroxylase-like immunoreactive neurons are likely to contain catecholamines. Approximately 225 tyrosine hydroxylase-like immunoreactive neurons are present in the Ventral Nerve Cord. The majority of these neurons appear to be interneurons. The suboesophageal ganglion contains the only unpaired neuron and the only pair of peripherally projecting tyrosine hydroxylase-like immunoreactive neurons in the Ventral Nerve Cord. The peripherally projecting neurons project to the salivary glands via the salivary Nerve. Each neuron in this pair is termed the salivary neuron 1. The remaining tyrosine hydroxylase-like immunoreactive neurons in the Ventral Nerve Cord are interneurons and exhibit a characteristic distribution within the thoracic and the abdominal ganglia. Serotoninlike immunoreactivity is also present in the salivary glands. Positive staining of the suboesophageal ganglion for serotoninlike immunoreactivity indicates the presence of several neuron pairs including a large pair along the Ventral posterior midline that project to the salivary glands via the salivary Nerve. Each neuron in this pair is termed the salivary neuron 2. Backfilling of the salivary Nerve with cobalt chloride reveals the presence of only two neurons within the suboesophageal ganglion that project to the salivary glands; these neurons are the salivary neurons 1 and 2. Reverse-phase high-performance liquid chromatography coupled with electrochemical detection of Ventral Nerve Cord and salivary gland homogenates confirms the presence of dopamine and serotonin.

  • Immunochemical staining of tyrosine hydroxylase(TH)-like material in the salivary glands and Ventral Nerve Cord of the cockroach, Periplaneta americana (L.)
    Journal of Insect Physiology, 1994
    Co-Authors: Andrew J. Elia, Declan W. Ali, Ian Orchard
    Abstract:

    Abstract This study examines the immunochemical staining of TH-like material in neurons of wholemount preparations of suboesophageal, thoracic and abdominal ganglia and salivary glands from immature and adult male cockroaches. A pair of neurons (SN1) in the suboesophageal ganglion, previously shown to contain catecholamines, stain intensely for TH-like material and are the only neurons identified which have a peripheral target (the salivary glands). The distribution of neurons containing TH-like immunoreactive material does not precisely overlap the distribution previously found for catecholamines using histofluorescence techniques. The axons of neurons which contain TH-like material in thoracic and abdominal ganglia appear to confine themselves to the central nervous system, thus suggesting that they probably function primarily to communicate and coordinate activity within the central nervous system. All neurons identified as containing TH-like material in the Ventral Nerve Cord and the suboesophageal ganglion are bilaterally symmetrical. Of treatments used to enhance immunochemical staining of TH-like material, only prior injection of animals with pargyline appeared to marginally improve resolution of positive neurons.

  • isolation sequence and bioactivity of fmrfamide related peptides from the locust Ventral Nerve Cord
    Peptides, 1994
    Co-Authors: Angela B Lange, Neda M Peeff, Ian Orchard
    Abstract:

    Abstract The Ventral Nerve Cord of the locust, Locusta migratoria , was examined for the presence of FMRFamide-related peptides (FaRPs). RP-HPLC coupled to an RIA specific for extended-RFamides revealed the presence of several FaRPs eluting at different percentages of acetonitrile. The sequences of five of these peptides were determined. Two sequences are identical to the two peptides previously sequenced from brain and retrocerebral complex of Locusta . These two peptides (PDVDHVFLRFamide and ADVGHVFLRFamide) were inhibitory when tested on locust oviduct contractions. The other peptides are novel with sequences of GQERNFLRFamide, AXXRNFIRFamide, and AFIRFamide. The synthesized peptides were stimulatory when tested on locust oviduct contractions, increasing the frequency and amplitude of spontaneous contractions and resulting in a basal contraction.

  • tyrosine hydroxylase like immunoreactivity in the Ventral Nerve Cord of the locust locusta migratoria including neurones innervating the salivary glands
    Journal of Insect Physiology, 1992
    Co-Authors: Ian Orchard, Angela B Lange, Brenda B Brown
    Abstract:

    Abstract The distribution of tyrosine hydroxylase-like immunoreactivity was mapped in whole-mount preparations of the Ventral Nerve Cord of adult male Locusta migratoria. Immunoreactivity was found in approx. 60 neuronal cell bodies and their processes distributed as bilaterally-symmetrical neurones throughout the various ganglia. Since tyrosine hydroxylase is the rate-limiting enzyme in catecholamine synthesis in vertebrates, it is likely that the neurones positive for tyrosine hydroxylase-like immunoreactivity in locust are catecholaminergic. The wide distribution of immunoreactivity indicates diverse functions for catecholamines in the locust. One function appears to be in the control of the salivary glands since an identifiable pair of neurones, the salivary neurones, SN1, are positive for tyrosine hydroxylase-like immunoreactivity. The remaining neurones appear to be interneurones with processes gaining in number and complexity in an anterior to posterior axis along the Nerve Cord. The mapping of these neurones is an initial step in the analysis of identifiable catecholamine-containing neurones in the locust.

Steffen Harzsch - One of the best experts on this subject based on the ideXlab platform.

  • Serotonin-immunoreactive neurons in the Ventral Nerve Cord of Remipedia (Crustacea): support for a sister group relationship of Remipedia and Hexapoda?
    BMC Evolutionary Biology, 2013
    Co-Authors: Torben Stemme, Steffen Harzsch, Thomas M Iliffe, Björn M Von Reumont, Stefan Koenemann, Gerd Bicker
    Abstract:

    Background Remipedia were initially seen as a primitive taxon within Pancrustacea based on characters considered ancestral, such as the homonomously segmented trunk. Meanwhile, several morphological and molecular studies proposed a more derived position of Remipedia within Pancrustacea, including a sister group relationship to Hexapoda. Because of these conflicting hypotheses, fresh data are crucial to contribute new insights into euarthropod phylogeny. The architecture of individually identifiable serotonin-immunoreactive neurons has successfully been used for phylogenetic considerations in Euarthropoda. Here, we identified neurons in three species of Remipedia with an antiserum against serotonin and compared our findings to reconstructed ground patterns in other euarthropod taxa. Additionally, we traced neurite connectivity and neuropil outlines using antisera against acetylated α-tubulin and synapsin. Results The Ventral Nerve Cord of Remipedia displays a typical rope-ladder-like arrangement of separate metameric ganglia linked by paired longitudinally projecting connectives. The peripheral projections comprise an intersegmental Nerve, consisting of two branches that fuse shortly after exiting the connectives, and the segmental anterior and posterior Nerve. The distribution and morphology of serotonin-immunoreactive interneurons in the trunk segments is highly conserved within the remipede species we analyzed, which allows for the reconstruction of a ground pattern: two posterior and one anterior pair of serotonin-immunoreactive neurons that possess a single contralateral projection. Additionally, three pairs of immunoreactive neurons are found in the medial part of each hemiganglion. In one species ( Cryptocorynetes haptodiscus ), the anterior pair of immunoreactive neurons is missing. Conclusions The anatomy of the remipede Ventral Nerve Cord with its separate metameric ganglia mirrors the external morphology of the animal’s trunk. The rope-ladder-like structure and principal architecture of the segmental ganglia in Remipedia corresponds closely to that of other Euarthropoda. A comparison of the serotonin-immunoreactive cell arrangement of Remipedia to reconstructed ground patterns of major euarthropod taxa supports a homology of the anterior and posterior neurons in Pancrustacea. These neurons in Remipedia possess unbranched projections across the midline, pointing towards similarities to the hexapod pattern. Our findings are in line with a growing number of phylogenetic investigations proposing Remipedia to be a rather derived crustacean lineage that perhaps has close affinities to Hexapoda.

  • serotonin immunoreactive neurons in the Ventral Nerve Cord of remipedia crustacea support for a sister group relationship of remipedia and hexapoda
    BMC Evolutionary Biology, 2013
    Co-Authors: Torben Stemme, Steffen Harzsch, Thomas M Iliffe, Stefan Koenemann, Bjorn M Von Reumont, Gerd Bicker
    Abstract:

    Remipedia were initially seen as a primitive taxon within Pancrustacea based on characters considered ancestral, such as the homonomously segmented trunk. Meanwhile, several morphological and molecular studies proposed a more derived position of Remipedia within Pancrustacea, including a sister group relationship to Hexapoda. Because of these conflicting hypotheses, fresh data are crucial to contribute new insights into euarthropod phylogeny. The architecture of individually identifiable serotonin-immunoreactive neurons has successfully been used for phylogenetic considerations in Euarthropoda. Here, we identified neurons in three species of Remipedia with an antiserum against serotonin and compared our findings to reconstructed ground patterns in other euarthropod taxa. Additionally, we traced neurite connectivity and neuropil outlines using antisera against acetylated α-tubulin and synapsin. The Ventral Nerve Cord of Remipedia displays a typical rope-ladder-like arrangement of separate metameric ganglia linked by paired longitudinally projecting connectives. The peripheral projections comprise an intersegmental Nerve, consisting of two branches that fuse shortly after exiting the connectives, and the segmental anterior and posterior Nerve. The distribution and morphology of serotonin-immunoreactive interneurons in the trunk segments is highly conserved within the remipede species we analyzed, which allows for the reconstruction of a ground pattern: two posterior and one anterior pair of serotonin-immunoreactive neurons that possess a single contralateral projection. Additionally, three pairs of immunoreactive neurons are found in the medial part of each hemiganglion. In one species (Cryptocorynetes haptodiscus), the anterior pair of immunoreactive neurons is missing. The anatomy of the remipede Ventral Nerve Cord with its separate metameric ganglia mirrors the external morphology of the animal’s trunk. The rope-ladder-like structure and principal architecture of the segmental ganglia in Remipedia corresponds closely to that of other Euarthropoda. A comparison of the serotonin-immunoreactive cell arrangement of Remipedia to reconstructed ground patterns of major euarthropod taxa supports a homology of the anterior and posterior neurons in Pancrustacea. These neurons in Remipedia possess unbranched projections across the midline, pointing towards similarities to the hexapod pattern. Our findings are in line with a growing number of phylogenetic investigations proposing Remipedia to be a rather derived crustacean lineage that perhaps has close affinities to Hexapoda.

  • embryonic development of the histaminergic system in the Ventral Nerve Cord of the marbled crayfish marmorkrebs
    Tissue & Cell, 2008
    Co-Authors: Verena Rieger, Steffen Harzsch
    Abstract:

    The embryonic development of neurotransmitter systems in crustaceans so far is poorly understood. Therefore, in the current study we monitored the ontogeny of histamine-immunoreactive neurons in the Ventral Nerve Cord of the Marbled Crayfish, an emerging crustacean model system for developmental studies. The first histaminergic neurons arise around 60% of embryonic development, well after the primordial axonal scaffold of the Ventral Nerve Cord has been established. This suggests that histaminergic neurons do not serve as pioneer neurons but that their axons follow well established axonal tracts. The developmental sequence of the different types of histaminergic neurons is charted in this study. The analysis of the histaminergic structures is also extended into adult specimens, showing a persistence of embryonic histaminergic neurons into adulthood. Our data are compared to the pattern of histaminergic neurons in other crustaceans and discussed with regard to our knowledge on other aspects of neurogenesis in Crustacea. Furthermore, the possible role of histaminergic neurons as characters in evolutionary considerations is evaluated.

  • ontogeny of the Ventral Nerve Cord in malacostracan crustaceans a common plan for neuronal development in crustacea hexapoda and other arthropoda
    Arthropod Structure & Development, 2003
    Co-Authors: Steffen Harzsch
    Abstract:

    Abstract This review sets out to summarize our current knowledge on the structural layout of the embryonic Ventral Nerve Cord in decapod crustaceans and its development from stem cell to the mature structure. In Decapoda, neuronal stem cells, the neuroblasts, mostly originate from ectodermal stem cells, the ectoteloblast, via a defined lineage. The neuroblasts undergo repeated asymmetric division and generate ganglion mother cells. The ganglion mother cells later divide again to give birth to ganglion cells (neurons) and there is increasing evidence now that ganglion mother cells divide again not only once but repeatedly. Various other aspects of neuroblast proliferation such as their temporal patterns of mitotic activity and spatial arrangement as well as the relation of neurogenesis to the development of the segmental appendages and maturation of motor behaviors are described. The link between cell lineage and cell differentiation in Decapoda so far has only been established for the midline neuroblast. However, there are several other identified early differentiating neurons, the outgrowing neurites of which pioneer the axonal scaffold within the neuromeres of the Ventral Nerve Cord. The maturation of identified neurons as examined by immunohistochemistry against their neurotransmitters or engrailed, is briefly described. These processes are compared to other Arthropoda (icluding Onychophora, Chelicerata, Diplopoda and Hexapoda) in order to shed light on variations and conserved motifs of the theme ‘neurogenesis’. The question of a ‘common plan for neuronal development’ in the Ventral Nerve Cords of Hexapoda and Crustacea is critically evaluated and the possibility of homologous neurons arising through divergent developmental pathways is discussed.

  • evolution of identified arthropod neurons the serotonergic system in relation to engrailed expressing cells in the embryonic Ventral Nerve Cord of the american lobster homarus americanus milne edwards 1873 malacostraca pleocyemata homarida
    Developmental Biology, 2003
    Co-Authors: Steffen Harzsch
    Abstract:

    One of the long-standing questions in zoology is that on the phylogenetic relationships within the Arthropoda. Comparative studies on structure and development of the nervous system can contribute important arguments to this discussion. In the present report, the arrangement of serotonin- and engrailed-expressing cells was examined in the embryonic Ventral Nerve Cord of the American lobster Homarus americanus Milne Edwards, 1873 (Malacostraca, Pleocyemata, Homarida), and the spatial relationship of these two cell classes was explored by a double-labelling approach. The goal of this study was to determine whether the lobster serotonergic neurons are homologous to similar cells present in representatives of the Hexapoda and other Arthropoda. The results indicate that, in fact, these neurons in the lobster Ventral Nerve Cord have corresponding counterparts in many other mandibulate taxa. Based on the finding of these homologies, the arrangement of serotonergic neurons in a model trunk ganglion of the mandibulate ground pattern was reconstructed as comprising an anterior and a posterior pair of serotonergic neurons per hemiganglion, each cell with both an ipsilateral and a contralateral neurite. Starting from this ground pattern, the evolutionary diversification of this class of neurons within the Mandibulata is discussed.

Gerd Bicker - One of the best experts on this subject based on the ideXlab platform.

  • Serotonin-immunoreactive neurons in the Ventral Nerve Cord of Remipedia (Crustacea): support for a sister group relationship of Remipedia and Hexapoda?
    BMC Evolutionary Biology, 2013
    Co-Authors: Torben Stemme, Steffen Harzsch, Thomas M Iliffe, Björn M Von Reumont, Stefan Koenemann, Gerd Bicker
    Abstract:

    Background Remipedia were initially seen as a primitive taxon within Pancrustacea based on characters considered ancestral, such as the homonomously segmented trunk. Meanwhile, several morphological and molecular studies proposed a more derived position of Remipedia within Pancrustacea, including a sister group relationship to Hexapoda. Because of these conflicting hypotheses, fresh data are crucial to contribute new insights into euarthropod phylogeny. The architecture of individually identifiable serotonin-immunoreactive neurons has successfully been used for phylogenetic considerations in Euarthropoda. Here, we identified neurons in three species of Remipedia with an antiserum against serotonin and compared our findings to reconstructed ground patterns in other euarthropod taxa. Additionally, we traced neurite connectivity and neuropil outlines using antisera against acetylated α-tubulin and synapsin. Results The Ventral Nerve Cord of Remipedia displays a typical rope-ladder-like arrangement of separate metameric ganglia linked by paired longitudinally projecting connectives. The peripheral projections comprise an intersegmental Nerve, consisting of two branches that fuse shortly after exiting the connectives, and the segmental anterior and posterior Nerve. The distribution and morphology of serotonin-immunoreactive interneurons in the trunk segments is highly conserved within the remipede species we analyzed, which allows for the reconstruction of a ground pattern: two posterior and one anterior pair of serotonin-immunoreactive neurons that possess a single contralateral projection. Additionally, three pairs of immunoreactive neurons are found in the medial part of each hemiganglion. In one species ( Cryptocorynetes haptodiscus ), the anterior pair of immunoreactive neurons is missing. Conclusions The anatomy of the remipede Ventral Nerve Cord with its separate metameric ganglia mirrors the external morphology of the animal’s trunk. The rope-ladder-like structure and principal architecture of the segmental ganglia in Remipedia corresponds closely to that of other Euarthropoda. A comparison of the serotonin-immunoreactive cell arrangement of Remipedia to reconstructed ground patterns of major euarthropod taxa supports a homology of the anterior and posterior neurons in Pancrustacea. These neurons in Remipedia possess unbranched projections across the midline, pointing towards similarities to the hexapod pattern. Our findings are in line with a growing number of phylogenetic investigations proposing Remipedia to be a rather derived crustacean lineage that perhaps has close affinities to Hexapoda.

  • serotonin immunoreactive neurons in the Ventral Nerve Cord of remipedia crustacea support for a sister group relationship of remipedia and hexapoda
    BMC Evolutionary Biology, 2013
    Co-Authors: Torben Stemme, Steffen Harzsch, Thomas M Iliffe, Stefan Koenemann, Bjorn M Von Reumont, Gerd Bicker
    Abstract:

    Remipedia were initially seen as a primitive taxon within Pancrustacea based on characters considered ancestral, such as the homonomously segmented trunk. Meanwhile, several morphological and molecular studies proposed a more derived position of Remipedia within Pancrustacea, including a sister group relationship to Hexapoda. Because of these conflicting hypotheses, fresh data are crucial to contribute new insights into euarthropod phylogeny. The architecture of individually identifiable serotonin-immunoreactive neurons has successfully been used for phylogenetic considerations in Euarthropoda. Here, we identified neurons in three species of Remipedia with an antiserum against serotonin and compared our findings to reconstructed ground patterns in other euarthropod taxa. Additionally, we traced neurite connectivity and neuropil outlines using antisera against acetylated α-tubulin and synapsin. The Ventral Nerve Cord of Remipedia displays a typical rope-ladder-like arrangement of separate metameric ganglia linked by paired longitudinally projecting connectives. The peripheral projections comprise an intersegmental Nerve, consisting of two branches that fuse shortly after exiting the connectives, and the segmental anterior and posterior Nerve. The distribution and morphology of serotonin-immunoreactive interneurons in the trunk segments is highly conserved within the remipede species we analyzed, which allows for the reconstruction of a ground pattern: two posterior and one anterior pair of serotonin-immunoreactive neurons that possess a single contralateral projection. Additionally, three pairs of immunoreactive neurons are found in the medial part of each hemiganglion. In one species (Cryptocorynetes haptodiscus), the anterior pair of immunoreactive neurons is missing. The anatomy of the remipede Ventral Nerve Cord with its separate metameric ganglia mirrors the external morphology of the animal’s trunk. The rope-ladder-like structure and principal architecture of the segmental ganglia in Remipedia corresponds closely to that of other Euarthropoda. A comparison of the serotonin-immunoreactive cell arrangement of Remipedia to reconstructed ground patterns of major euarthropod taxa supports a homology of the anterior and posterior neurons in Pancrustacea. These neurons in Remipedia possess unbranched projections across the midline, pointing towards similarities to the hexapod pattern. Our findings are in line with a growing number of phylogenetic investigations proposing Remipedia to be a rather derived crustacean lineage that perhaps has close affinities to Hexapoda.

Torben Stemme - One of the best experts on this subject based on the ideXlab platform.

  • Histaminergic interneurons in the Ventral Nerve Cord: assessment of their value for Euarthropod phylogeny
    Zoological Letters, 2019
    Co-Authors: Maite Maurer, Thomas M Iliffe, Janina Hladik, Torben Stemme
    Abstract:

    Despite numerous approaches to the resolution of euarthropod phylogeny, mainly based on modern sequence information and traditional external morphology, the resulting hypotheses are often contradictory and leave many questions about euarthropod evolution unanswered. The comparison of developmental and structural aspects of the nervous system has shown to be a valuable contribution to the assessment of current phylogenetic hypotheses. One promising approach for the generation of new character sets is the morphology of transmitter systems and the discovery of individually identifiable neurons, which allow phylogenetic comparisons on the single cell level. In this context, the serotonin transmitter system has been investigated to a considerable degree. Studies to date have yielded important stimuli to our understanding of euarthropod relationships and the evolution of their nervous systems. However, data on other transmitter systems remain fragmented, and their value with respect to phylogenetic questions remains speculative. The biogenic amine histamine is a promising transmitter; a substantial amount of data has been reported in the literature and the homology of some histaminergic neurons has been suggested. Here, we present a comprehensive review of histaminergic neurons in the Ventral Nerve Cord of Euarthropoda. Using immunocytochemical labeling of histamine combined with confocal laser-scanning microscopy, we investigated the transmitter system in phylogenetically relevant taxa, such as Zygentoma, Remipedia, Diplopoda, and Arachnida. By reconstructing ground patterns, we evaluated the significance of this specific character set for euarthropod phylogeny. With this approach, we identified a set of neurons, which can be considered homologous within the respective major taxon. In conclusion, the histaminergic system contains useful information for our understanding of euarthropod phylogeny, supporting the proposed clades Tetraconata and Mandibulata. Furthermore, this character set has considerable potential to help resolve relationships within the major clades at a deeper level of taxonomy, due to the considerable variability in neurite morphology.

  • serotonergic neurons in the Ventral Nerve Cord of chilopoda a mandibulate pattern of individually identifiable neurons
    Zoological Letters, 2017
    Co-Authors: Andy Sombke, Torben Stemme
    Abstract:

    Given the numerous hypotheses concerning arthropod phylogeny, independent data are needed to supplement knowledge based on traditional external morphology and modern molecular sequence information. One promising approach involves comparisons of the structure and development of the nervous system. Along these lines, the morphology of serotonin-immunoreactive neurons in the Ventral Nerve Cord has been investigated in numerous tetraconate taxa (Crustacea and Hexapoda). It has been shown that these neurons can be identified individually due to their comparably low number, characteristic soma position, and neurite morphology, thus making it possible to establish homologies at the single cell level. Within Chilopoda (centipedes), detailed analyses of major branching patterns of serotonin-immunoreactive neurons are missing, but are crucial for developing meaningful conclusions on the homology of single cells. In the present study, we re-investigated the distribution and projection patterns of serotonin-immunoreactive neurons in the Ventral Nerve Cord of three centipede species: Scutigera coleoptrata, Lithobius forficatus, and Scolopendra oraniensis. The centipede serotonergic system in the Ventral Nerve Cord contains defined groups of individually identifiable neurons. An anterior and two posterior immunoreactive neurons per hemiganglion with contralateral projections, a pair of ipsilateral projecting lateral neurons (an autapomorphic character for Chilopoda), as well as a postero-lateral group of an unclear number of cells are present in the ground pattern of Chilopoda. Comparisons to the patterns of serotonin-immunoreactive neurons of tetraconate taxa support the homology of anterior and posterior neurons. Our results thus support a sister group relationship of Myriapoda and Tetraconata and, further, a mandibulate ground pattern of individually identifiable serotonin-immunoreactive neurons in the Ventral Nerve Cord. Medial neurons are not considered to be part of the tetraconate ground pattern, but could favor the ‘Miracrustacea hypothesis’, uniting Remipedia, Cephalocarida, and Hexapoda.

  • Serotonergic neurons in the Ventral Nerve Cord of Chilopoda – a mandibulate pattern of individually identifiable neurons
    BMC, 2017
    Co-Authors: Andy Sombke, Torben Stemme
    Abstract:

    Abstract Background Given the numerous hypotheses concerning arthropod phylogeny, independent data are needed to supplement knowledge based on traditional external morphology and modern molecular sequence information. One promising approach involves comparisons of the structure and development of the nervous system. Along these lines, the morphology of serotonin-immunoreactive neurons in the Ventral Nerve Cord has been investigated in numerous tetraconate taxa (Crustacea and Hexapoda). It has been shown that these neurons can be identified individually due to their comparably low number, characteristic soma position, and neurite morphology, thus making it possible to establish homologies at the single cell level. Within Chilopoda (centipedes), detailed analyses of major branching patterns of serotonin-immunoreactive neurons are missing, but are crucial for developing meaningful conclusions on the homology of single cells. Results In the present study, we re-investigated the distribution and projection patterns of serotonin-immunoreactive neurons in the Ventral Nerve Cord of three centipede species: Scutigera coleoptrata, Lithobius forficatus, and Scolopendra oraniensis. The centipede serotonergic system in the Ventral Nerve Cord contains defined groups of individually identifiable neurons. An anterior and two posterior immunoreactive neurons per hemiganglion with contralateral projections, a pair of ipsilateral projecting lateral neurons (an autapomorphic character for Chilopoda), as well as a postero-lateral group of an unclear number of cells are present in the ground pattern of Chilopoda. Conclusions Comparisons to the patterns of serotonin-immunoreactive neurons of tetraconate taxa support the homology of anterior and posterior neurons. Our results thus support a sister group relationship of Myriapoda and Tetraconata and, further, a mandibulate ground pattern of individually identifiable serotonin-immunoreactive neurons in the Ventral Nerve Cord. Medial neurons are not considered to be part of the tetraconate ground pattern, but could favor the ‘Miracrustacea hypothesis’, uniting Remipedia, Cephalocarida, and Hexapoda

  • Serotonin-immunoreactive neurons in the Ventral Nerve Cord of Remipedia (Crustacea): support for a sister group relationship of Remipedia and Hexapoda?
    BMC Evolutionary Biology, 2013
    Co-Authors: Torben Stemme, Steffen Harzsch, Thomas M Iliffe, Björn M Von Reumont, Stefan Koenemann, Gerd Bicker
    Abstract:

    Background Remipedia were initially seen as a primitive taxon within Pancrustacea based on characters considered ancestral, such as the homonomously segmented trunk. Meanwhile, several morphological and molecular studies proposed a more derived position of Remipedia within Pancrustacea, including a sister group relationship to Hexapoda. Because of these conflicting hypotheses, fresh data are crucial to contribute new insights into euarthropod phylogeny. The architecture of individually identifiable serotonin-immunoreactive neurons has successfully been used for phylogenetic considerations in Euarthropoda. Here, we identified neurons in three species of Remipedia with an antiserum against serotonin and compared our findings to reconstructed ground patterns in other euarthropod taxa. Additionally, we traced neurite connectivity and neuropil outlines using antisera against acetylated α-tubulin and synapsin. Results The Ventral Nerve Cord of Remipedia displays a typical rope-ladder-like arrangement of separate metameric ganglia linked by paired longitudinally projecting connectives. The peripheral projections comprise an intersegmental Nerve, consisting of two branches that fuse shortly after exiting the connectives, and the segmental anterior and posterior Nerve. The distribution and morphology of serotonin-immunoreactive interneurons in the trunk segments is highly conserved within the remipede species we analyzed, which allows for the reconstruction of a ground pattern: two posterior and one anterior pair of serotonin-immunoreactive neurons that possess a single contralateral projection. Additionally, three pairs of immunoreactive neurons are found in the medial part of each hemiganglion. In one species ( Cryptocorynetes haptodiscus ), the anterior pair of immunoreactive neurons is missing. Conclusions The anatomy of the remipede Ventral Nerve Cord with its separate metameric ganglia mirrors the external morphology of the animal’s trunk. The rope-ladder-like structure and principal architecture of the segmental ganglia in Remipedia corresponds closely to that of other Euarthropoda. A comparison of the serotonin-immunoreactive cell arrangement of Remipedia to reconstructed ground patterns of major euarthropod taxa supports a homology of the anterior and posterior neurons in Pancrustacea. These neurons in Remipedia possess unbranched projections across the midline, pointing towards similarities to the hexapod pattern. Our findings are in line with a growing number of phylogenetic investigations proposing Remipedia to be a rather derived crustacean lineage that perhaps has close affinities to Hexapoda.

  • serotonin immunoreactive neurons in the Ventral Nerve Cord of remipedia crustacea support for a sister group relationship of remipedia and hexapoda
    BMC Evolutionary Biology, 2013
    Co-Authors: Torben Stemme, Steffen Harzsch, Thomas M Iliffe, Stefan Koenemann, Bjorn M Von Reumont, Gerd Bicker
    Abstract:

    Remipedia were initially seen as a primitive taxon within Pancrustacea based on characters considered ancestral, such as the homonomously segmented trunk. Meanwhile, several morphological and molecular studies proposed a more derived position of Remipedia within Pancrustacea, including a sister group relationship to Hexapoda. Because of these conflicting hypotheses, fresh data are crucial to contribute new insights into euarthropod phylogeny. The architecture of individually identifiable serotonin-immunoreactive neurons has successfully been used for phylogenetic considerations in Euarthropoda. Here, we identified neurons in three species of Remipedia with an antiserum against serotonin and compared our findings to reconstructed ground patterns in other euarthropod taxa. Additionally, we traced neurite connectivity and neuropil outlines using antisera against acetylated α-tubulin and synapsin. The Ventral Nerve Cord of Remipedia displays a typical rope-ladder-like arrangement of separate metameric ganglia linked by paired longitudinally projecting connectives. The peripheral projections comprise an intersegmental Nerve, consisting of two branches that fuse shortly after exiting the connectives, and the segmental anterior and posterior Nerve. The distribution and morphology of serotonin-immunoreactive interneurons in the trunk segments is highly conserved within the remipede species we analyzed, which allows for the reconstruction of a ground pattern: two posterior and one anterior pair of serotonin-immunoreactive neurons that possess a single contralateral projection. Additionally, three pairs of immunoreactive neurons are found in the medial part of each hemiganglion. In one species (Cryptocorynetes haptodiscus), the anterior pair of immunoreactive neurons is missing. The anatomy of the remipede Ventral Nerve Cord with its separate metameric ganglia mirrors the external morphology of the animal’s trunk. The rope-ladder-like structure and principal architecture of the segmental ganglia in Remipedia corresponds closely to that of other Euarthropoda. A comparison of the serotonin-immunoreactive cell arrangement of Remipedia to reconstructed ground patterns of major euarthropod taxa supports a homology of the anterior and posterior neurons in Pancrustacea. These neurons in Remipedia possess unbranched projections across the midline, pointing towards similarities to the hexapod pattern. Our findings are in line with a growing number of phylogenetic investigations proposing Remipedia to be a rather derived crustacean lineage that perhaps has close affinities to Hexapoda.

Gerhard Scholtz - One of the best experts on this subject based on the ideXlab platform.

  • Serotonin-immunoreactivity in the Ventral Nerve Cord of Pycnogonida – support for individually identifiable neurons as ancestral feature of the arthropod nervous system
    BMC Evolutionary Biology, 2015
    Co-Authors: Georg Brenneis, Gerhard Scholtz
    Abstract:

    Background The arthropod Ventral Nerve Cord features a comparably low number of serotonin-immunoreactive neurons, occurring in segmentally repeated arrays. In different crustaceans and hexapods, these neurons have been individually identified and even inter-specifically homologized, based on their soma positions and neurite morphologies. Stereotypic sets of serotonin-immunoreactive neurons are also present in myriapods, whereas in the investigated chelicerates segmental neuron clusters with higher and variable cell numbers have been reported. This led to the suggestion that individually identifiable serotonin-immunoreactive neurons are an apomorphic feature of the Mandibulata. To test the validity of this neurophylogenetic hypothesis, we studied serotonin-immunoreactivity in three species of Pycnogonida (sea spiders). This group of marine arthropods is nowadays most plausibly resolved as sister group to all other extant chelicerates, rendering its investigation crucial for a reliable reconstruction of arthropod nervous system evolution. Results In all three investigated pycnogonids, the Ventral walking leg ganglia contain different types of serotonin-immunoreactive neurons, the somata of which occurring mostly singly or in pairs within the ganglionic cortex. Several of these neurons are readily and consistently identifiable due to their stereotypic soma position and characteristic neurite morphology. They can be clearly homologized across different ganglia and different specimens as well as across the three species. Based on these homologous neurons, we reconstruct for their last common ancestor (presumably the pycnogonid stem species) a minimal repertoire of at least seven identified serotonin-immunoreactive neurons per hemiganglion. Beyond that, each studied species features specific pattern variations, which include also some neurons that were not reliably labeled in all specimens. Conclusions Our results unequivocally demonstrate the presence of individually identifiable serotonin-immunoreactive neurons in the pycnogonid Ventral Nerve Cord. AcCordingly, the validity of this neuroanatomical feature as apomorphy of Mandibulata is questioned and we suggest it to be ancestral for arthropods instead. The pronounced disparities between the segmental pattern in pycnogonids and the one of studied euchelicerates call for denser sampling within the latter taxon. By contrast, overall similarities between the pycnogonid and myriapod patterns may be indicative of single cell homologies in these two taxa. This notion awaits further substantiation from future studies.

  • serotonin immunoreactivity in the Ventral Nerve Cord of pycnogonida support for individually identifiable neurons as ancestral feature of the arthropod nervous system
    BMC Evolutionary Biology, 2015
    Co-Authors: Georg Brenneis, Gerhard Scholtz
    Abstract:

    The arthropod Ventral Nerve Cord features a comparably low number of serotonin-immunoreactive neurons, occurring in segmentally repeated arrays. In different crustaceans and hexapods, these neurons have been individually identified and even inter-specifically homologized, based on their soma positions and neurite morphologies. Stereotypic sets of serotonin-immunoreactive neurons are also present in myriapods, whereas in the investigated chelicerates segmental neuron clusters with higher and variable cell numbers have been reported. This led to the suggestion that individually identifiable serotonin-immunoreactive neurons are an apomorphic feature of the Mandibulata. To test the validity of this neurophylogenetic hypothesis, we studied serotonin-immunoreactivity in three species of Pycnogonida (sea spiders). This group of marine arthropods is nowadays most plausibly resolved as sister group to all other extant chelicerates, rendering its investigation crucial for a reliable reconstruction of arthropod nervous system evolution. In all three investigated pycnogonids, the Ventral walking leg ganglia contain different types of serotonin-immunoreactive neurons, the somata of which occurring mostly singly or in pairs within the ganglionic cortex. Several of these neurons are readily and consistently identifiable due to their stereotypic soma position and characteristic neurite morphology. They can be clearly homologized across different ganglia and different specimens as well as across the three species. Based on these homologous neurons, we reconstruct for their last common ancestor (presumably the pycnogonid stem species) a minimal repertoire of at least seven identified serotonin-immunoreactive neurons per hemiganglion. Beyond that, each studied species features specific pattern variations, which include also some neurons that were not reliably labeled in all specimens. Our results unequivocally demonstrate the presence of individually identifiable serotonin-immunoreactive neurons in the pycnogonid Ventral Nerve Cord. AcCordingly, the validity of this neuroanatomical feature as apomorphy of Mandibulata is questioned and we suggest it to be ancestral for arthropods instead. The pronounced disparities between the segmental pattern in pycnogonids and the one of studied euchelicerates call for denser sampling within the latter taxon. By contrast, overall similarities between the pycnogonid and myriapod patterns may be indicative of single cell homologies in these two taxa. This notion awaits further substantiation from future studies.