Head development in the onychophoran <i>Euperipatoides kanangrensis</i> with particular reference to the central nervous system

Eriksson, Bo; Tait, Noel; Budd, Graham E.

doi:10.1002/jmor.10034

Cited by 135 publications

(119 citation statements)

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“…In arthropods the expression is less clear with some examples of expression in more posterior structures but it appear as if the original expression in arthropods is restricted to the protocerebrum (Browne et al, 2006;Finkelstein and Perrimon, 1991;Hirth et al, 2003;Li et al, 1996;Telford and Thomas, 1998), which is the first neuromere of arthropods. The present data thus support earlier claims that the onychophoran antenna is situated on the most anterior neuromere (Eriksson et al, 2009;Eriksson and Budd, 2000;Eriksson et al, 2003;Mayer and Koch, 2005;Sedgwick, 1887), and hence, the onychophoran antenna is not homologous to the insect antenna or its equivalent structures on other arthropods.…”

Section: Eka-otd and Head Segmentationsupporting

confidence: 88%

“…The onychophoran antenna is situated in the six3 expressing area and this is supporting earlier investigations that claim that the onychophoran antenna is an appendage of the most anterior neuromere (Eriksson and Budd, 2000;Eriksson et al, 2003).…”

Section: Eka-six3 and Head Segmentationsupporting

confidence: 86%

“…A segment is normally defined as a repetitive unit with structures such as neuromeres, coelomic cavities, appendages, annuli, set of muscles and nephridia (Scholtz, 2002). Apart from annuli and muscle sets, all of these characters are associated with each of the three onychophoran head neuromeres (Eriksson and Budd, 2000;Eriksson et al, 2003;Mayer and Koch, 2005;Sedgwick, 1887;Storch and Ruhberg, 1993) and Eriksson et al (2009) reported engrailed expression in each of these units, and therefore, it seems correct to apply the term segment to these three units. However, we know that the most anterior segment, the antennal segment, carries unique characters that distinguishes it from the two other head segments, which apart from morphological differences appearing relatively late in development, are very similar to the trunk segments.…”

Section: Eka-six3 and Head Segmentationmentioning

confidence: 99%

“…Is it an appendage or structure of a pre ocular segment (Posnien et al, 2009;Schmidt-Ott et al, 1994;Schmidt-Ott and Technau, 1992), the ocular segment (Budd, 2002;Eriksson and Budd, 2000;Eriksson et al, 2003) and homologous to the great appendage or primary antenna of certain fossil stem-group arthropods (Budd, 2002;Scholtz and Edgecombe, 2005) or a limb belonging to a segment placed further posterior (Haas et al, 2001a;Haas et al, 2001b). There have been suggestions that the antenna of the onychophorans corresponds to the labrum of arthropods (Budd, 2002;Eriksson and Budd, 2000;Eriksson et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Both phyla, together with the related tardigrades, are segmented and therefore probably share a segmented ancestor. Since onychophorans have a less complicated head made up of fewer appendage bearing segments than arthropods (Eriksson and Budd, 2000;Eriksson et al, 2003;Mayer and Koch, 2005;Strausfeld et al, 2006), and hence, easier to identify, we decided to investigate the expression pattern of anterior Hox-genes together with the head patterning genes six3 and otd in order to align homologous segments and other areas between onychophorans and arthropods with the aim to try and clarify the nature of the pre oral region of onychophorans and arthropods.…”

Section: Introductionmentioning

confidence: 99%

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Head patterning and Hox gene expression in an onychophoran and its implications for the arthropod head problem

et al. 2010

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Akam, M. (2010) Head patterning and Hox gene expression in an onychophoran and its implications for the arthropod head problem.Development, Genes and Evolution, Onychophoran head segmentation ABSTRACT The arthropod head problem has been a long lasting conundrum which has puzzled arthropodists for more than a century. Onychophorans are the sister group of the arthropods and are a phylum that has for a long time been regarded as the link between a simple worm-like arthropod ancestor and the crown-group arthropods. The arthropod head is a complicated structure with cryptic segment borders because of fusion and migration of segments; hence the long standing debate of the different parts segmental origin. The onychophorans on the other hand have a rather simple head comprising three well defined segments during development, which gives rise to an adult head with three appendages that are specialised for sensory and food capture/manipulative purposes. Based on the expression pattern of the anterior hox-genes; labial, proboscipaedia, hox3 and Deformed, as well as the head patterning genes otd and six3, we show that these three segments and their appendages can be correlated to the segments of the arthropod proto-deuto-and trito-cerebrum and that the onychophoran antenna is an appendage associated with the most anterior territory of the onychophoran head, it is the frontal appendage or primary antenna of stem-group arthropods and its affinities to the arthropod labrum is discussed.

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Section: Eka-otd and Head Segmentationsupporting

confidence: 88%

Section: Eka-six3 and Head Segmentationsupporting

confidence: 86%

Section: Eka-six3 and Head Segmentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Head patterning and Hox gene expression in an onychophoran and its implications for the arthropod head problem

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Evolution of early development of the nervous system: a comparison between arthropods

Stollewerk

Simpson

2005

BioEssays

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Large numbers of cells with unique neuronal specificity are generated during development of the central nervous system of animals. Here we discuss the events that generate cell diversity during early development of the ventral nerve cord of different arthropod groups. Neural precursors are generated in a spatial array in the epithelium of each hemisegment over a period of time. Spatial cues within the epithelium are thought to evolve as embryogenesis proceeds. This spatiotemporal information might generate diversity among the neural precursors in all arthropod groups, although the mechanisms regulating the positioning of individual precursors have diverged. However, distinct strategies for the generation of neuronal diversity have evolved in the different arthropod lineages that appear to correlate with specific modes of ontogenesis. We hypothesize that an evolutionary trend towards reduced cell numbers and possibly rapid embryogenesis in insects has culminated in the appearance of stereotyped neuroblast lineages.

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Distribution of serotonin in the trunk of Metaperipatus blainvillei (Onychophora, Peripatopsidae): Implications for the evolution of the nervous system in Arhropoda

Mayer

Harzsch

2008

J of Comparative Neurology

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Onychophora ("velvet worms") are a key taxon in the discussion of arthropod phylogeny. Studies that analyze neuroanatomical characters against a phylogenetic background have recently provided new insights into this debate. However, to date only a few studies on nervous system organization, particularly in the trunk, are available in Onychophora. To close this gap and to compare the onychophoran nervous system with that of other bilaterians, we have analyzed the pattern of serotonin-like immunoreactivity in Metaperipatus blainvillei (Peripatopsidae). In addition to confirming previous histological observations, our experiments revealed many new aspects of nervous system organization in Onychophora. The serotonergic nervous system of M. blainvillei consists of five longitudinal nerve strands (the paired dorsolateral nerves, the heart nerve, and the paired ventral cords), which are interconnected at regular intervals by ring commissures as well as median commissures. The ring commissures are absent in the leg-bearing regions. In addition to the main nerve tracts, there are several extensive fiber networks innervating the integument, the nephridial organs, and the body musculature. The leg nerves and nephridial nerves represent the only strictly segmental neuronal structures. We conclude that the general architecture of the onychophoran nervous system in the trunk closely resembles the orthogonal organization that is present in various other groups of Bilateria, which suggests that the arthropod nervous system is derived from such an orthogonal pattern. This finding implies that the "rope ladder-like" nervous system may have arisen independently in Panarthropoda and Annelida and does not represent a synapomorphy of these groups.

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Head development in the onychophoran Euperipatoides kanangrensis with particular reference to the central nervous system

Cited by 135 publications

References 50 publications

Head patterning and Hox gene expression in an onychophoran and its implications for the arthropod head problem

Head patterning and Hox gene expression in an onychophoran and its implications for the arthropod head problem

Evolution of early development of the nervous system: a comparison between arthropods

Distribution of serotonin in the trunk of Metaperipatus blainvillei (Onychophora, Peripatopsidae): Implications for the evolution of the nervous system in Arhropoda

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