Click
here to close Hello! We notice that
you are using Internet Explorer, which is not supported by Echinobase
and may cause the site to display incorrectly. We suggest using a
current version of Chrome,
FireFox,
or Safari.
J Morphol
2018 May 01;2795:589-597. doi: 10.1002/jmor.20794.
Show Gene links
Show Anatomy links
SALMFamide2 and serotonin immunoreactivity in the nervous system of some acoels (Xenacoelomorpha).
Dittmann IL
,
Zauchner T
,
Nevard LM
,
Telford MJ
,
Egger B
.
???displayArticle.abstract???
Acoel worms are simple, often microscopic animals with direct development, a multiciliated epidermis, a statocyst, and a digestive parenchyma instead of a gut epithelium. Morphological characters of acoels have been notoriously difficult to interpret due to their relative scarcity. The nervous system is one of the most accessible and widely used comparative features in acoels, which have a so-called commissural brain without capsule and several major longitudinal neurite bundles. Here, we use the selective binding properties of a neuropeptide antibody raised in echinoderms (SALMFamide2, or S2), and a commercial antibody against serotonin (5-HT) to provide additional characters of the acoel nervous system. We have prepared whole-mount immunofluorescent stainings of three acoel species: Symsagittifera psammophila (Convolutidae), Aphanostoma pisae, and the model acoel Isodiametra pulchra (both Isodiametridae). The commissural brain of all three acoels is delimited anteriorly by the ventral anterior commissure, and posteriorly by the dorsal posterior commissure. The dorsal anterior commissure is situated between the ventral anterior commissure and the dorsal posterior commissure, while the statocyst lies between dorsal anterior and dorsal posterior commissure. S2 and serotonin do not co-localise, and they follow similar patterns to each other within an animal. In particular, S2, but not 5-HT, stains a prominent commissure posterior to the main (dorsal) posterior commissure. We have for the first time observed a closed posterior loop of the main neurite bundles in S. psammophila for both the amidergic and the serotonergic nervous system. In I. pulchra, the lateral neurite bundles also form a posterior loop in our serotonergic nervous system stainings.
Figure 1. Live images of the three acoel species used in this study: (a) Symsagittifera psammophila, (b) Aphanostoma pisae, (c) Isodiametra pulchra. Note that in (a) a juvenile is shown, while stainings have been performed with adults in all cases
Figure 2.
Symsagittifera psammophila stained with S2 antibody (a–e, magenta) and 5‐HT antibody (e, yellow). (a) Projection of whole‐mount. (b) Projection of the anterior body‐part. (c) Projection of the posterior body‐part. (d) Confocal projection with temporal colour coding; colour‐code: pink (dorsal) to orange/red (ventral). (e) Overlay projection of the anterior body‐part of a double‐labelled animal. (a–c, e) Same individual. Abbreviations: 1 dorsal neurite bundle; 2 lateral neurite bundle; 3 ventral neurite bundle; ac dorsal anterior commissure; cc collum commissure; fr frontal ring; m mouth; pc dorsal posterior commissure; plo posterior loop. Asterisk marks position of statocyst
Figure 3. Confocal projection of Isodiametra pulchra stained with S2 antibody (a,b,e, magenta) and 5‐HT (c–e, yellow). (a) Confocal projections of a whole‐mount and (b) of the anterior body part with temportal colour coding, colour‐code: grey (dorsal) to red (ventral). Green arrowhead points to delicate anterior process of neurites. (c) Confocal projections of a whole‐mount and (d) of the anterior body‐part. (e) Overlay projection of the anterior body part of a double‐labelled animal. Green arrowheads point to delicate anterior process of neurites. (f‐g) Schematic drawings of the nervous system stained with S2 (f) and 5‐HT (g) antibodies. (h) Detailed view of bipolar and multipolar (red and white arrowheads, respectively) neurons of the colour‐coded (blue dorsal, red ventral) S2amidergic nervous system. (a,b), (c,d), (e,h) same individuals. Abbreviations: 1 dorsal neurite bundle; 2 lateral neurite bundle; 3 ventral neurite bundle; 4 medio‐ventral neurite bundle; ac: dorsal anterior commissure; al anterior lobe; cop male copulatory organ; fr frontal ring; m mouth; pc dorsal posterior commissure; pl posterior lobe. Asterisks mark position of statocyst
Figure 4. Confocal projection of a whole‐mount Aphanostoma pisae stained with S2 antibody with temporal colour coding. Colour‐code: pink (ventral) to red (dorsal), arrowheads point to putative neuronal cell bodies of bipolar (white) or multipolar (red) neurons. Abbreviations: 1 dorsal neurite bundle; 2 lateral neurite bundle; 3 ventral neurite bundle; ac dorsal anterior commissure; cop male copulatory organ; fr frontal ring; m mouth; pc dorsal posterior commissure. Asterisk marks the position of the statocyst
Figure 5. Schematic drawings of the nervous systems stained with S2 (magenta) and 5‐HT (yellow) antibodies. (a) Symsagittifera psammophila. (b) Isodiametra pulchra. (c) Aphanostoma pisae 5‐HT (yellow) after Zauchner et al. (2015). Abbreviations: 1 dorsal neurite bundle; 2 lateral neurite bundle; 3 ventral neurite bundle; 4 medio‐ventral neurite bundle; ac dorsal anterior commissure; al anterior lobe; cc collum commissure; fr frontal ring; pc dorsal posterior commissure; pl posterior lobe. Asterisks mark position of statocyst
Figure 6.
Symsagittifera psammophila stained with 5‐HT antibody. Projections of a whole‐mount (a), of the anterior body‐part (b) and of the posterior body‐part (c). (a–c) Same individual. Abbreviations: 1 dorsal neurite bundle; 2 lateral neurite bundle; 3 ventral neurite bundle; ac dorsal anterior commissure; fr frontal ring; pc dorsal posterior commissure; plo posterior loop. Asterisks mark position of statocyst
Achatz,
The Acoela: on their kind and kinships, especially with nemertodermatids and xenoturbellids (Bilateria incertae sedis).
2013, Pubmed
Achatz,
The Acoela: on their kind and kinships, especially with nemertodermatids and xenoturbellids (Bilateria incertae sedis).
2013,
Pubmed
Achatz,
The nervous system of Isodiametra pulchra (Acoela) with a discussion on the neuroanatomy of the Xenacoelomorpha and its evolutionary implications.
2012,
Pubmed
Bailly,
The chimerical and multifaceted marine acoel Symsagittifera roscoffensis: from photosymbiosis to brain regeneration.
2014,
Pubmed
Bery,
Structure of the central nervous system of a juvenile acoel, Symsagittifera roscoffensis.
2010,
Pubmed
Cannon,
Xenacoelomorpha is the sister group to Nephrozoa.
2016,
Pubmed
Elphick,
The SALMFamides: a new family of neuropeptides isolated from an echinoderm.
1991,
Pubmed
,
Echinobase
Gavilán,
Xenacoelomorpha: a case of independent nervous system centralization?
2016,
Pubmed
Hejnol,
Acoel development supports a simple planula-like urbilaterian.
2008,
Pubmed
Hejnol,
Assessing the root of bilaterian animals with scalable phylogenomic methods.
2009,
Pubmed
Jondelius,
How the worm got its pharynx: phylogeny, classification and Bayesian assessment of character evolution in Acoela.
2011,
Pubmed
Kotikova,
[Architectonics of the central nervous system in Acoela, Plathelminthes, and Rotifera].
2008,
Pubmed
Lapraz,
Put a tiger in your tank: the polyclad flatworm Maritigrella crozieri as a proposed model for evo-devo.
2013,
Pubmed
Lechauve,
Neuroglobins, pivotal proteins associated with emerging neural systems and precursors of metazoan globin diversity.
2013,
Pubmed
Moreno,
Inferring the ancestral function of the posterior Hox gene within the bilateria: controlling the maintenance of reproductive structures, the musculature and the nervous system in the acoel flatworm Isodiametra pulchra.
2010,
Pubmed
Newman,
Tissue distribution of the SALMFamide neuropeptides S1 and S2 in the starfish Asterias rubens using novel monoclonal and polyclonal antibodies. I. Nervous and locomotory systems.
1995,
Pubmed
,
Echinobase
Philippe,
Acoelomorph flatworms are deuterostomes related to Xenoturbella.
2011,
Pubmed
,
Echinobase
Philippe,
Acoel flatworms are not platyhelminthes: evidence from phylogenomics.
2007,
Pubmed
Raikova,
Basiepidermal nervous system in Nemertoderma westbladi (Nemertodermatida): GYIRFamide immunoreactivity.
2004,
Pubmed
Raikova,
The brain of the Nemertodermatida (Platyhelminthes) as revealed by anti-5HT and anti-FMRFamide immunostainings.
2000,
Pubmed
Reuter,
An endocrine brain? The pattern of FMRF-amide immunoreactivity in Acoela (Plathelminthes).
1998,
Pubmed
Reuter,
Organisation of the nervous system in the Acoela: an immunocytochemical study.
2001,
Pubmed
Rouse,
New deep-sea species of Xenoturbella and the position of Xenacoelomorpha.
2016,
Pubmed
Semmler,
Steps towards a centralized nervous system in basal bilaterians: insights from neurogenesis of the acoel Symsagittifera roscoffensis.
2010,
Pubmed
Sikes,
Radical modification of the A-P axis and the evolution of asexual reproduction in Convolutriloba acoels.
2008,
Pubmed
Sikes,
Making heads from tails: development of a reversed anterior-posterior axis during budding in an acoel.
2010,
Pubmed
Sprecher,
Functional brain regeneration in the acoel worm Symsagittifera roscoffensis.
2015,
Pubmed
Srivastava,
Whole-body acoel regeneration is controlled by Wnt and Bmp-Admp signaling.
2014,
Pubmed
Veenstra,
Neuropeptide evolution: neurohormones and neuropeptides predicted from the genomes of Capitella teleta and Helobdella robusta.
2011,
Pubmed
Zauchner,
A cultivable acoel species from the Mediterranean, Aphanostoma pisae sp. nov. (Acoela, Acoelomorpha).
2015,
Pubmed
