The structure of Archiannelid<i>Dinophilus gyrociliatus</i>ventral nerve cords

Fofanova, Elizaveta; Voronezhskaya, Elena E.

doi:10.1556/abiol.63.2012.suppl.2.11

Cited by 11 publications

(16 citation statements)

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“…They have externally indistinct segmentation, recognized only by the arrangement of transverse ciliary bands [32, 38, 39] and internal features such as lateral nerves, commissures, and nephridia [11, 40, 41]. The family Dinophilidae contains Trilobodrilus with six described species [30, 42–46] and Dinophilus, which is represented by approximately ten species [32, 38, 47–52], since the validity of several additional taxa is questioned due to ambiguous or insufficiently detailed morphological descriptions.…”

Section: Introductionmentioning

confidence: 99%

“…Despite several anatomical studies [11, 32, 40, 41, 56, 57, 69–72], little is known about the neuromuscular development in Dinophilus , which is thoroughly assessed in this study. However, previous studies did already assess the adult stages, stating that the musculature consists mainly of the pharyngeal [73] and body wall musculature, which is specified as layers of circular, diagonal, and longitudinal musculature [39].…”

Section: Introductionmentioning

confidence: 99%

“…However, previous studies did already assess the adult stages, stating that the musculature consists mainly of the pharyngeal [73] and body wall musculature, which is specified as layers of circular, diagonal, and longitudinal musculature [39]. The nervous system has likewise been investigated in mainly adults, assessing the relatively simple brain and a ventral nervous system consisting of five to seven longitudinal nerve cords [11, 40, 41, 71]. These are connected by one (in monomorphic) or three commissures (in dimorphic species) per segment, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of neuromuscular development in two dinophilid species (Annelida) suggests progenetic origin of Dinophilus gyrociliatus

et al. 2016

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BackgroundSeveral independent meiofaunal lineages are suggested to have originated through progenesis, however, morphological support for this heterochronous process is still lacking. Progenesis is defined as an arrest of somatic development (synchronously in various organ systems) due to early maturation, resulting in adults resembling larvae or juveniles of the ancestors. Accordingly, we established a detailed neuromuscular developmental atlas of two closely related Dinophilidae using immunohistochemistry and CLSM. This allows us to test for progenesis, questioning whether i) the adult smaller, dimorphic Dinophilus gyrociliatus resembles a younger developmental stage of the larger, monomorphic D. taeniatus and whether ii) dwarf males of D. gyrociliatus resemble an early developmental stage of D. gyrociliatus females.ResultsBoth species form longitudinal muscle bundles first, followed by circular muscles, creating a grid of body wall musculature, which is the densest in adult D. taeniatus, while the architecture in adult female D. gyrociliatus resembles that of prehatching D. taeniatus. Both species display a subepidermal ganglionated nervous system with an anterior dorsal brain and five longitudinal ventral nerve bundles with six sets of segmental commissures (associated with paired ganglia). Neural differentiation of D. taeniatus and female D. gyrociliatus commissures occurs before hatching: both species start out forming one transverse neurite bundle per segment, which are thereafter joined by additional thin bundles. Whereas D. gyrociliatus arrests its development at this stage, adult D. taeniatus condenses the thin commissures again into one thick commissural bundle per segment. Generally, D. taeniatus adults demonstrate a seemingly more organized (= segmental) pattern of serotonin-like and FMRFamide-like immunoreactive elements. The dwarf male of D. gyrociliatus displays a highly aberrant neuromuscular system, showing no close resemblance to any early developmental stage of female Dinophilus, although the onset of muscular development mirrors the early myogenesis in females.ConclusionThe apparent synchronous arrest of nervous and muscular development in adult female D. gyrociliatus, resembling the prehatching stage of D. taeniatus, suggests that D. gyrociliatus have originated through progenesis. The synchrony in arrest of three organ systems, which show opposing reduction and addition of elements, presents one of the morphologically best-argued cases of progenesis within Spiralia.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparison of neuromuscular development in two dinophilid species (Annelida) suggests progenetic origin of Dinophilus gyrociliatus

et al. 2016

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“…Dinophilidae is a species-poor meiofaunal group, whose members occupy interstitial habitats and lives in the crevices of sandy sediment or in biofilms on macroalgae in tidal marine regions [54–56]. It comprises two clades, Dinophilus and Trilobodrilus , whose representatives share their diminutive body size and being only few segments long pseudocoelomates with protonephridia, lacking chaetae, parapodia and appendages, but having a dense ventral ciliary field and direct development [45, 57–59].…”

Section: Introductionmentioning

confidence: 99%

Molecular regionalization in the compact brain of the meiofaunal annelid Dinophilus gyrociliatus (Dinophilidae)

Kerbl

Martín-Durán

Worsaae

et al. 2016

EvoDevo

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BackgroundAnnelida is a morphologically diverse animal group that exhibits a remarkable variety in nervous system architecture (e.g., number and location of longitudinal cords, architecture of the brain). Despite this heterogeneity of neural arrangements, the molecular profiles related to central nervous system patterning seem to be conserved even between distantly related annelids. In particular, comparative molecular studies on brain and anterior neural region patterning genes have focused so far mainly on indirect-developing macrofaunal taxa. Therefore, analyses on microscopic, direct-developing annelids are important to attain a general picture of the evolutionary events underlying the vast diversity of annelid neuroanatomy.ResultsWe have analyzed the expression domains of 11 evolutionarily conserved genes involved in brain and anterior neural patterning in adult females of the direct-developing meiofaunal annelid Dinophilus gyrociliatus. The small, compact brain shows expression of dimmed, foxg, goosecoid, homeobrain, nk2.1, orthodenticle, orthopedia, pax6, six3/6 and synaptotagmin-1. Although most of the studied markers localize to specific brain areas, the genes six3/6 and synaptotagmin-1 are expressed in nearly all perikarya of the brain. All genes except for goosecoid, pax6 and nk2.2 overlap in the anterior brain region, while the respective expression domains are more separated in the posterior brain.ConclusionsOur findings reveal that the expression patterns of the genes foxg, orthodenticle, orthopedia and six3/6 correlate with those described in Platynereis dumerilii larvae, and homeobrain, nk2.1, orthodenticle and synaptotagmin-1 resemble the pattern of late larvae of Capitella teleta. Although data on other annelids are limited, molecular similarities between adult Dinophilus and larval Platynereis and Capitella suggest an overall conservation of molecular mechanisms patterning the anterior neural regions, independent from developmental and ecological strategies, or of the size and configuration of the nervous system.Electronic supplementary materialThe online version of this article (doi:10.1186/s13227-016-0058-2) contains supplementary material, which is available to authorized users.

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“…These features make D. gyrociliatus a popular candidate for studying sex ratio and determination (Åkesson and Costlow 1991;Prevedelli and Vandini 1999;Prevedelli and Simonini 2000;Simonini and Prevedelli 2003). Relatively easy to culture, D. gyrociliatus also make a good model for neurological studies (M€ uller and Westheide 2002;Fofanova and Voronezhskaya 2012). Although Dinophilidae were once placed close to dorvilleid annelids, their phylogenetic affinities are uncertain (Figure 1) (Struck et al 2015).…”

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confidence: 99%