A New Spiralian Phylogeny Places the Enigmatic Arrow Worms among Gnathiferans

Marlétaz, Ferdinand; Peijnenburg, Katja T. C. A.; Goto, Taichiro; Satoh, Noriyuki; Rokhsar, Daniel S.

doi:10.1016/j.cub.2018.11.042

Cited by 235 publications

(300 citation statements)

References 47 publications

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“…This indicates that lox2 evolved only after split of the common ancestor of those clades from remaining Spiralia and does not belong to the ancestral hox complement of all Spiralia (16). Whether absence of lox2 in lophophorates is plesiomorphic or represents evolutionary reversal depends on the position of Lophophorata within Spiralia, which is still debatable and not fully resolved (52)(53)(54)(55)94).…”

Section: Hox Gene Complement In Phoronidamentioning

confidence: 99%

“…Brachiopoda -into the group called Lophophorata (50,51), which recently gained support as a valid clade from several transcriptomic and phylogenomic studies (52)(53)(54)(55). Although originally the Lophophorata were considered as deuterostomes (50,51), molecular data showed their protostome affinity (56) and currently the lophophorates occupy a wellsupported position within the clade of Spiralia (52)(53)(54)(55)57). Phoronids develop through a distinctive planktotrophic larval stage, called actinotrocha (58)(59)(60)(61).…”

Section: Introductionmentioning

confidence: 99%

“…ancestor of all phoronids. Recent studies are favoring a sister group relationship between phoronids and ectoprocts(52)(53)(54)(55)94), the latter of which possesses a mineralized external shell similarly as brachiopods. However, the Hox gene survey using degenerate polymerase chain reaction primers in ectoproct Crisularia (Bugula) turrita did not retrieve neither scr nor post1 sequences(95), which questions the possible correlation between loss of scr and post1 and the reduction of shell secreting tissues in phoronid lineage.…”

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Hox gene expression during the development of the phoronidPhoronopsis harmeri

Gąsiorowski

Hejnol

2019

Preprint

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Background: Phoronida is a small group of marine worm-like suspension feeders, which together with brachiopods and bryozoans form the clade Lophophorata. Although their development is well studied on the morphological level, data regarding gene expression during this process are scarce and restricted to the analysis of relatively few transcription factors. Here we present a description of the expression patterns of Hox genes during the embryonic and larval development of the phoronid Phoronopsis harmeri. Results:We identified sequences of 8 Hox genes in the transcriptome of P. harmeri and determined their expression pattern during embryonic and larval development using whole mount in situ hybridization. We found that none of the Hox genes is expressed during embryonic development. Instead their expression is initiated in the later developmental stages, when the larval body is already formed. The Hox genes are expressed in the metasomal sac, posterior mesoderm and junction between midgut and hindgut -structures that represent rudiments of the adult worm, which emerges through the process of drastic

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Section: Hox Gene Complement In Phoronidamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Hox gene expression during the development of the phoronidPhoronopsis harmeri

Gąsiorowski

Hejnol

2019

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“…The Gnathifera, i.e. sister taxon to the Lophotrochozoa, comprise Chaetognatha, Rotifera, Gnathostomulida, and Micrognathozoa and have not yet been investigated with respect to genes underlying photoreceptor formation and function (Figure 1; Marlétaz et al 2019). Chaetognaths, commonly known as arrow worms, are a rather small taxon of marine, torpedo-shaped coelomic animals with horizontally projecting fins, and cuticular grasping spines to catch prey (Shinn 1997).…”

Section: Introductionmentioning

confidence: 99%

“…aspects of gastrulation process) as well as protostomes (nervous system development). Hence their phylogenetic position has been contentious for a long time until phylogenetic analyses recently placed them within the Gnathifera (summarized by Harzsch et al 2015;Marlétaz et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Characterization of eyes, photoreceptors and opsins in developmental stages of the chaetognath Spadella cephaloptera

Wollesen¹,

Monje

Oel

et al. 2019

Preprint

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The phylogenetic position of chaetognaths has been debated for decades, however recently they have been grouped into the Gnathifera, sister taxon to the Lophotrochozoa. Chaetognaths possess photoreceptor cells that are anatomically unique and arranged remarkably different in the eyes of the various species. Studies investigating eye development and underlying gene regulatory networks are so far missing.In order to gain insights into the development and the molecular toolkit of chaetognath photoreceptors and eyes a new transcriptome of the epibenthic species Spadella cephaloptera was searched for opsins. Our screen revealed single-copies of xenopsin and peropsin and gene expression analyses demonstrated that only xenopsin is expressed in photoreceptor cells of the developing lateral eyes. Adults likewise exhibit two xenopsin+ photoreceptor cells in each of their lateral eyes. Beyond that, a single cryptochrome gene was uncovered and found coexpressed with xenopsin in some photoreceptor cells of the lateral developing eye. In addition, it is co-expressed with peropsin in the cerebral ganglia, a condition reminiscent of a non-visual photoreceptive zone in the apical nervous system of the annelid Platynereis dumerilii that performs circadian entrainment and melatonin release. Cryptochrome expression was also detected in cells of the corona ciliata, a circular organ in the posterior dorsal head region that has been attributed several functions arguing for an involvement of this organ in circadian entrainment. Our study demonstrates the importance to investigate representatives of the Gnathifera, a clade that has been neglected with respect to developmental studies and that might contribute to unravel the evolution of spiralian and bilaterian body plans.

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Rotifera

Walsh

Hochberg

Uyhelj

et al. 2021

Encyclopedia of Life Sciences

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The phylum Rotifera comprises two disparate groups. Traditionally, rotifers were viewed as a small taxon of tiny, bilaterally symmetrical, unsegmented aquatic invertebrates. However, recent molecular analyses indicate that Acanthocephala, a group of obligatorily parasitic worms, are highly modified rotifers. (They are covered separately in the ELS.) Rotifers may be found anywhere water exists for a sufficient period allowing them to reproduce including lakes and ponds, ephemeral pools, water films coating terrestrial mosses and soil particles and brackish and coastal marine waters. Few are parasitic. In some habitats, rotifers may achieve high population densities (>1000 individuals per litre). Being consumers of bacteria, algae, protists and other rotifers, they are important in transferring energy to higher trophic levels. Because they serve as food for young fishes and are easily cultured, rotifers are grown in mass quantities for commercial aquaculture. They also serve as models for research on ageing, evolution of sex and ecotoxicology. Key Concepts Rotifers live in fresh and saline continental waters, in the moisture covering some plants such as mosses, in damp soils and in the interstitial spaces of aquatic sediments. Although not as abundant as in inland waters, rotifers often flourish in nearshore marine waters and estuaries. A few species live a parasitic life within the cytoplasm of certain large freshwater algae and the guts of freshwater, aquatic oligochaetes. Some rotifer populations crash when they become infected with parasitic fungi or microsporozoan parasites. Feeding mainly on other microscopic organisms, including bacteria, algae, protists and other rotifers, these small metazoans are important basal consumers in aquatic systems. They are a component of the microbial loop in which nutrients cycle and energy flows within the lower trophic levels. When consumed by higher trophic levels (e.g. aquatic arthropods and fishes) rotifers play an important role connecting the microbial loop to the classic food web. Rotifers possess several interesting features. The cell membranes between the cells of certain tissues in rotifers fuse, thereby forming a cytoplasmic syncytium. The body wall contains proteins that are only shared with one other group of invertebrates, the Acanthocephala. Many rotifers are capable of undergoing dormancy in a resting state that allows them to avoid harsh conditions. Rotifers are a first food for the larvae of many organisms; thus, they have been exploited by aquaculturists to maintain commercially important fishes, crabs and shrimps. Also, because rotifers are comparatively easy to culture and possess relatively short life spans, they are used in ageing studies and to assess the toxicity of heavy metals, pesticides, pharmaceuticals and other pollutants. Some species have specific ecological requirements making them useful as indicators of water quality. Being one of the few taxa capable of cyclical parthenogenesis, rotifers are also used as models for the study of the evolution of sex. The phylogenetic position of Rotifera has not been fully resolved, but they appear to be related to a group of small, jawed metazoans called the Gnathifera. Emerging molecular evidence indicates that the phylum Acanthocephala — a taxon of worm‐like parasites — should be considered to be highly modified rotifers (Witek et al ., 2009).

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A New Spiralian Phylogeny Places the Enigmatic Arrow Worms among Gnathiferans

Cited by 235 publications

References 47 publications

Hox gene expression during the development of the phoronidPhoronopsis harmeri

Hox gene expression during the development of the phoronidPhoronopsis harmeri

Characterization of eyes, photoreceptors and opsins in developmental stages of the chaetognath Spadella cephaloptera

Rotifera

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