Structure and occurrence of cyphonautes larvae (bryozoa, ectoprocta)

Nielsen, Claus; Worsaae, Katrine

doi:10.1002/jmor.10856

Cited by 33 publications

(28 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…9 and 11a). Expression of six3/6 clears from 2c R2 and 4B, but persists in the inner cells of the forming apical organ, a central neural region occupied by serotonergic-positive cells in other cyphonautes larvae [64]. We detected dlx transcripts, a gene involved in neurogenesis and proximodistal patterning of flies and vertebrates [65], in the eight animal pole cells (1q) of the 16-cell stage (5.2 hpa), broadly in the apical disc during gastrulation and elongation and, finally, localized to the whole apical organ in the late gastrula (Fig.…”

Section: Resultsmentioning

confidence: 99%

Cleavage modification did not alter blastomere fates during bryozoan evolution

2017

View full text Add to dashboard Cite

BackgroundStereotypic cleavage patterns play a crucial role in cell fate determination by precisely positioning early embryonic blastomeres. Although misplaced cell divisions can alter blastomere fates and cause embryonic defects, cleavage patterns have been modified several times during animal evolution. However, it remains unclear how evolutionary changes in cleavage impact the specification of blastomere fates. Here, we analyze the transition from spiral cleavage – a stereotypic pattern remarkably conserved in many protostomes – to a biradial cleavage pattern, which occurred during the evolution of bryozoans.ResultsUsing 3D-live imaging time-lapse microscopy (4D-microscopy), we characterize the cell lineage, MAPK signaling, and the expression of 16 developmental genes in the bryozoan Membranipora membranacea. We found that the molecular identity and the fates of early bryozoan blastomeres are similar to the putative homologous blastomeres in spiral-cleaving embryos.ConclusionsOur work suggests that bryozoans have retained traits of spiral development, such as the early embryonic fate map, despite the evolution of a novel cleavage geometry. These findings provide additional support that stereotypic cleavage patterns can be modified during evolution without major changes to the molecular identity and fate of embryonic blastomeres.Electronic supplementary materialThe online version of this article (doi:10.1186/s12915-017-0371-9) contains supplementary material, which is available to authorized users.

show abstract

Section: Resultsmentioning

confidence: 99%

Cleavage modification did not alter blastomere fates during bryozoan evolution

2017

View full text Add to dashboard Cite

show abstract

“…Animals were examined alive and fixed for various morphological studies and DNA sequencing following published methods [48], [78] (see Table 1). Live images and video-recordings were made with a Sony HDR-XR520 mounted on a Zeiss AX10 microscope with DIC as well as an Olympus C-5060 mounted on a Leitz Dialux 20 microscope with phase contrast.…”

Section: Methodsmentioning

confidence: 99%

An Anatomical Description of a Miniaturized Acorn Worm (Hemichordata, Enteropneusta) with Asexual Reproduction by Paratomy

et al. 2012

Self Cite

View full text Add to dashboard Cite

The interstitial environment of marine sandy bottoms is a nutrient-rich, sheltered habitat whilst at the same time also often a turbulent, space-limited, and ecologically challenging environment dominated by meiofauna. The interstitial fauna is one of the most diverse on earth and accommodates miniaturized representatives from many macrofaunal groups as well as several exclusively meiofaunal phyla. The colonization process of this environment, with the restrictions imposed by limited space and low Reynolds numbers, has selected for great morphological and behavioral changes as well as new life history strategies.Here we describe a new enteropneust species inhabiting the interstices among sand grains in shallow tropical waters of the West Atlantic. With a maximum body length of 0.6 mm, it is the first microscopic adult enteropneust known, a group otherwise ranging from 2 cm to 250 cm in adult size. Asexual reproduction by paratomy has been observed in this new species, a reproductive mode not previously reported among enteropneusts.Morphologically, Meioglossus psammophilus gen. et sp. nov. shows closest resemblance to an early juvenile stage of the acorn worm family Harrimaniidae, a result congruent with its phylogenetic placement based on molecular data. Its position, clearly nested within the larger macrofaunal hemichordates, suggests that this represents an extreme case of miniaturization. The evolutionary pathway to this simple or juvenile appearance, as chiefly demonstrated by its small size, dense ciliation, and single pair of gill pores, may be explained by progenesis. The finding of M. psammophilus gen. et sp. nov. underscores the notion that meiofauna may constitute a rich source of undiscovered metazoan diversity, possibly disguised as juveniles of other species.

show abstract

“…those having a larva) versus those undergoing direct development. Additional literature was accessed for phyla not included in Wald (1981), as described below. All species in the phyla Cnidaria, Ctenophora, Nematomorpha, and Porifera undergo metamorphosis (Wald 1981), as do Bryozoa (Nielsen and Worsaae 2010). For Platyhelminthes, most undergo metamorphosis, although a few turbellarian species seemingly undergo direct development (Wald 1981).…”

Section: Overviewmentioning

confidence: 99%

“…All species in the phyla Cnidaria, Ctenophora, Nematomorpha, and Porifera undergo metamorphosis (Wald 1981), as do Bryozoa (Nielsen and Worsaae 2010). For Platyhelminthes, most undergo metamorphosis, although a few turbellarian species seemingly undergo direct development (Wald 1981).…”

Section: Overviewmentioning

confidence: 99%

What Explains Patterns of Diversification and Richness among Animal Phyla?

Jezkova

Wiens

2017

The American Naturalist

View full text Add to dashboard Cite

Animal phyla vary dramatically in species richness (from 1 species to >1.2 million), but the causes of this variation remain largely unknown. Animals have also evolved striking variation in morphology and ecology, including sessile marine taxa lacking heads, eyes, limbs, and complex organs (e.g. sponges), parasitic worms (e.g. nematodes, platyhelminths), and taxa with eyes, skeletons, limbs, and complex organs that dominate terrestrial ecosystems (arthropods, chordates). Relating this remarkable variation in traits to the diversification and richness of animal phyla is a fundamental yet unresolved problem in biology. Here, we test the impacts of 18 traits (including morphology, ecology, reproduction, and development) on diversification and richness of extant animal phyla. Using phylogenetic multiple regression, the best-fitting model includes five traits that explain ~74% of the variation in diversification rates (dioecy, parasitism, eyes/photoreceptors, a skeleton, non-marine habitat). However, a model including just three (skeleton, parasitism, habitat) explains nearly as much variation (~67%). Diversification rates then largely explain richness patterns. Our results also identify many striking traits that have surprisingly little impact on diversification (e.g. head, limbs, and complex circulatory and digestive systems). Overall, our results reveal the key factors that shape large-scale patterns of diversification and richness across >80% of all extant, described species.

show abstract

Structure and occurrence of cyphonautes larvae (bryozoa, ectoprocta)

Cited by 33 publications

References 27 publications

Cleavage modification did not alter blastomere fates during bryozoan evolution

Cleavage modification did not alter blastomere fates during bryozoan evolution

An Anatomical Description of a Miniaturized Acorn Worm (Hemichordata, Enteropneusta) with Asexual Reproduction by Paratomy

What Explains Patterns of Diversification and Richness among Animal Phyla?

Contact Info

Product

Resources

About