Onychophora

Mayer, Georg; Franke, Franziska Anni; Treffkorn, Sandra; Gross, Vladimir; Oliveira, Ivo de Sena

doi:10.1007/978-3-7091-1865-8_4

Cited by 38 publications

(79 citation statements)

References 157 publications

(332 reference statements)

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“…All procedures in this investigation complied with international and institutional guidelines, including the guidelines for animal welfare as laid down by the German Research Foundation (DFG). We have chosen the model onychophoran E. rowelli as the focus of our study because many aspects of its biology, including anatomy, development, reproduction, and phylogeny, have been investigated extensively [83]. …”

Section: Methodsmentioning

confidence: 99%

Assessing segmental versus non-segmental features in the ventral nervous system of onychophorans (velvet worms)

et al. 2017

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BackgroundDue to their phylogenetic position as one of the closest arthropod relatives, studies of the organisation of the nervous system in onychophorans play a key role for understanding the evolution of body segmentation in arthropods. Previous studies revealed that, in contrast to the arthropods, segmentally repeated ganglia are not present within the onychophoran ventral nerve cords, suggesting that segmentation is either reduced or might be incomplete in the onychophoran ventral nervous system.ResultsTo assess segmental versus non-segmental features in the ventral nervous system of onychophorans, we screened the nerve cords for various markers, including synapsin, serotonin, gamma-aminobutyric acid, RFamide, dopamine, tyramine and octopamine. In addition, we performed retrograde fills of serially repeated commissures and leg nerves to localise the position of neuronal somata supplying those. Our data revealed a mixture of segmental and non-segmental elements within the onychophoran nervous system.ConclusionsWe suggest that the segmental ganglia of arthropods evolved by a gradual condensation of subsets of neurons either in the arthropod or the arthropod-tardigrade lineage. These findings are in line with the hypothesis of gradual evolution of segmentation in panarthropods and thus contradict a loss of ancestral segmentation within the onychophoran lineage.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0853-3) contains supplementary material, which is available to authorized users.

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Section: Methodsmentioning

confidence: 99%

Assessing segmental versus non-segmental features in the ventral nervous system of onychophorans (velvet worms)

et al. 2017

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“…Neurol. 523:1865-1885, 2015 V C 2015 Wiley Periodicals, Inc. INDEXING TERMS: immunohistochemistry; nervous system; PDF; PDH; gene duplication; RRID: AB_2315090; RRID: AB_477585 Pigment-dispersing factor (PDF) refers to a family of structurally and functionally related neuropeptides that are commonly found in the nervous system of ecdysozoans, including nematodes and insects, as well as in crustaceans, where they are referred to as pigmentdispersing hormone (PDH; for review see Meelkop et al, 2010). Peptides of this family act either as neurohormones or as neuromodulators and neurotransmitters to fulfill numerous functions ranging from the control of integument color change and dispersal of visual shading pigment to the modulation of the circadian rhythm (see, e.g., Helfrich-F€ orster, 2009;Hsu et al, 2008;Meelkop et al, 2010Meelkop et al, , 2012N€ assel and Winther, 2010;Persson et al, 2001;Rao, 2001;Reischig et al, 2004;Strauss and Dircksen, 2010;Strauß et al, 2011;Verde et al, 2007).…”

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confidence: 99%

Evolution of pigment‐dispersing factor neuropeptides in panarthropoda: Insights from onychophora (velvet worms) and tardigrada (water bears)

Mayer

Hering

Stosch

et al. 2015

J of Comparative Neurology

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Pigment-dispersing factor (PDF) denotes a conserved family of homologous neuropeptides present in several invertebrate groups, including mollusks, nematodes, insects, and crustaceans (referred to here as pigment-dispersing hormone [PDH]). With regard to their encoding genes (pdf, pdh), insects possess only one, nematodes two, and decapod crustaceans up to three, but their phylogenetic relationship is unknown. To shed light on the origin and diversification of pdf/pdh homologs in Panarthropoda (Onychophora + Tardigrada + Arthropoda) and other molting animals (Ecdysozoa), we analyzed the transcriptomes of five distantly related onychophorans and a representative tardigrade and searched for putative pdf homologs in publically available genomes of other protostomes. This revealed only one pdf homolog in several mollusk and annelid species; two in Onychophora, Priapulida, and Nematoda; and three in Tardigrada. Phylogenetic analyses suggest that the last common ancestor of Panarthropoda possessed two pdf homologs, one of which was lost in the arthropod or arthropod/tardigrade lineage, followed by subsequent duplications of the remaining homolog in some taxa. Immunolocalization of PDF-like peptides in six onychophoran species, by using a broadly reactive antibody that recognizes PDF/PDH peptides in numerous species, revealed an elaborate system of neurons and fibers in their central and peripheral nervous systems. Large varicose projections in the heart suggest that the PDF neuropeptides functioned as both circulating hormones and locally released transmitters in the last common ancestor of Onychophora and Arthropoda. The lack of PDF-like-immunoreactive somata associated with the onychophoran optic ganglion conforms to the hypothesis that onychophoran eyes are homologous to the arthropod median ocelli.

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“…They are surrounded by a vitelline envelope and a chorion that persists until birth. In contrast to this, the neotropical peripatid P. hitoyensis displays placentotrophic viviparity ( sensu Mayer et al, ), with yolkless embryos that are not surrounded by any secreted envelopes. Instead, the embryos are connected to the uterus wall of the mother via a placental stalk, which is a derivative of the dorsal extra‐embryonic tissue (Fig.…”

Section: Introductionmentioning

confidence: 97%

“…The peripatopsid E. rowelli exhibits a combined lecithotrophic/ matrotrophic viviparity (sensu Mayer et al, 2015), formerly referred to as "ovoviviparity" (e.g. Sunnucks et al, 2000;Walker and Tait, 2004).…”

Section: Introductionmentioning

confidence: 99%

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Conserved versus derived patterns of controlled cell death during the embryonic development of two species of Onychophora (velvet worms)

Treffkorn

Mayer

2017

Developmental Dynamics

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Despite the different developmental modes in these onychophoran species, our data suggest that patterns of apoptosis are conserved among onychophorans. While apoptosis in the dorsal extra-embryonic tissue might contribute to dorsal closure-a process also known from arthropods-the involvement of apoptosis in ventral closure might be unique to onychophorans. Apoptosis in the placental stalk of P. hitoyensis is most likely a derived feature of the placentotrophic onychophorans. Developmental Dynamics 246:403-416, 2017. © 2017 Wiley Periodicals, Inc.

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Onychophora

Cited by 38 publications

References 157 publications

Assessing segmental versus non-segmental features in the ventral nervous system of onychophorans (velvet worms)

Assessing segmental versus non-segmental features in the ventral nervous system of onychophorans (velvet worms)

Evolution of pigment‐dispersing factor neuropeptides in panarthropoda: Insights from onychophora (velvet worms) and tardigrada (water bears)

Conserved versus derived patterns of controlled cell death during the embryonic development of two species of Onychophora (velvet worms)

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