The organization and evolutionary implications of neuropils and their neurons in the brain of the onychophoran Euperipatoides rowelli

Strausfeld, Nicholas J.; Strausfeld, Camilla Mok; Stowe, Sally; Rowell, David M.; Loesel, Rudolf

doi:10.1016/j.asd.2006.06.002

Cited by 95 publications

(126 citation statements)

References 52 publications

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“…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%

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: Introductionmentioning

confidence: 99%

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

et al. 2010

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“…At this stage, neuroblasts become visible that segregate from the placode to form two populations, the outer and inner optic anlagen. Similar brain centers have been identified in different representatives of the arthropod groups; however, it is not clear in many cases whether these structures are homologous (Strausfeld et al, 2006a;Strausfeld, 1998). In insects, for example, the mushroom bodies (MBs) receive predominantly secondary olfactory input and are involved in olfactory learning and memory.…”

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confidence: 97%

“…However, the homology between central body and a structure with the same name in chelicerates (Hanstroem, 1928) was challenged because of distinctive functional-anatomical features (Homberg, 2008;Loesel et al, 2002;Strausfeld et al, 2006b). Strausfeld therefore named the chelicerate midline neuropile the ''arcuate body'' (Strausfeld et al, 2006a). Data on the development of brain compartments are fragmentary for insects and crustaceans and are all but missing for chelicerates and myriapods apart from a few classical studies (e.g., Anderson, 1973;Harzsch and Glötz-ner, 2002;Meinertzhagen and Hanson, 1993;Oland and Tolbert, 2003;Tettamanti et al, 1997;Weygoldt, 1985).…”

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confidence: 98%

Compartmentalization of the precheliceral neuroectoderm in the spider Cupiennius salei: Development of the arcuate body, optic ganglia, and mushroom body

Doeffinger

Hartenstein

Stollewerk

2010

J of Comparative Neurology

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Similarly to vertebrates, arthropod brains are compartmentalized into centers with specific neurological functions such as cognition, behavior, and memory. The centers can be further subdivided into smaller functional units. This raises the question of how these compartments are formed during development and how they are integrated into brain centers. We show here for the first time how the precheliceral neuroectoderm of the spider Cupiennius salei is compartmentalized to form the distinct brain centers of the visual system: the optic ganglia, the mushroom bodies, and the arcuate body. The areas of the visual brain centers are defined by the formation of grooves and vesicles and express the proneural gene CsASH1, followed by expression of the neural differentiation marker Prospero. Furthermore, the transcription factor dachshund, which is strongly enriched in the mushroom bodies and the outer optic ganglion of Drosophila, is expressed in the optic anlagen and the mushroom bodies of the spider. The developing brain centers are further subdivided into single neural precursor groups, which become incorporated into the grooves and vesicles but remain distinguishable throughout development, suggesting that they encode spatial information for neural subtype identity. Several molecular and morphological aspects of the development of the optic ganglia and the mushroom bodies are similar in the spider and in insects. Furthermore, we show that the primary engrailed head spot contributes neurons to the optic ganglia of the median eyes, whereas the secondary head spot, which has been associated with the optic ganglia in insects and crustaceans, is absent.

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“…Mushroom bodies are found in polychaete annelids, turbellarian platyhelminths, onychophorans, and many, but not all arthropods [53][54][55][56]. They are best studied in the insects, where they are likely to have arisen in a common ancestor prior to the divergence of the wingless Zygentoma (silverfish and firebrats) [37,57].…”

Section: Factors Driving Homoplasy In Higher Brain Centresmentioning

confidence: 99%

Evolution of brain elaboration

Farris¹

2015

Phil. Trans. R. Soc. B

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One contribution of 16 to a discussion meeting issue 'Origin and evolution of the nervous system'. Large, complex brains have evolved independently in several lineages of protostomes and deuterostomes. Sensory centres in the brain increase in size and complexity in proportion to the importance of a particular sensory modality, yet often share circuit architecture because of constraints in processing sensory inputs. The selective pressures driving enlargement of higher, integrative brain centres has been more difficult to determine, and may differ across taxa. The capacity for flexible, innovative behaviours, including learning and memory and other cognitive abilities, is commonly observed in animals with large higher brain centres. Other factors, such as social grouping and interaction, appear to be important in a more limited range of taxa, while the importance of spatial learning may be a common feature in insects with large higher brain centres. Despite differences in the exact behaviours under selection, evolutionary increases in brain size tend to derive from common modifications in development and generate common architectural features, even when comparing widely divergent groups such as vertebrates and insects. These similarities may in part be influenced by the deep homology of the brains of all Bilateria, in which shared patterns of developmental gene expression give rise to positionally, and perhaps functionally, homologous domains. Other shared modifications of development appear to be the result of homoplasy, such as the repeated, independent expansion of neuroblast numbers through changes in genes regulating cell division. The common features of large brains in so many groups of animals suggest that given their common ancestry, a limited set of mechanisms exist for increasing structural and functional diversity, resulting in many instances of homoplasy in bilaterian nervous systems.

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The organization and evolutionary implications of neuropils and their neurons in the brain of the onychophoran Euperipatoides rowelli

Cited by 95 publications

References 52 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

Compartmentalization of the precheliceral neuroectoderm in the spider Cupiennius salei: Development of the arcuate body, optic ganglia, and mushroom body

Evolution of brain elaboration

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