Re-discovery and novel contributions to morphology and multigene phylogeny of Myxophyllum steenstrupi (Ciliophora: Pleuronematida), an obligate symbiont of terrestrial pulmonates

2020 ◽  
Author(s):  
Tengyue Zhang ◽  
Peter Vďačný
Keyword(s):  
Phylogenetic Analyses ◽  
Mantle Cavity ◽  
The Body ◽  
Body Region ◽  
Multigene Phylogeny ◽  
Nuclear Markers ◽  
Free Living ◽  
Obligate Symbiont ◽  
First Time ◽  
Posterior Body Region

Abstract Myxophyllum steenstrupi is a symbiotic ciliate living in the body slime and mantle cavity of terrestrial pulmonates (Gastropoda: Pulmonata). In the present study, M. steenstrupi was re-discovered after almost 30 years and characterized using an integrative morpho-molecular approach for the first time. Myxophyllum is distinguished by a broadly ovate, about 140 × 115 μm-sized body, a nuclear apparatus typically composed of seven macronuclear nodules and a single micronucleus, a central contractile vacuole, a shallow oral cavity situated in the posterior body region and dense somatic ciliature with extensive thigmotactic field. According to the present phylogenetic analyses of two mitochondrial and five nuclear markers, M. steenstrupi is classified in the predominantly free-living order Pleuronematida (Oligohymenophorea: Scuticociliatia). This order also encompasses other taxa isolated from molluscs and traditionally classified along with Myxophyllum in the order Thigmotrichida. The proper classifications of Myxophyllum was hampered by the dramatic remodelling of its oral apparatus (reduction of the paroral membrane and adoral organelles, formation of vestibular kineties), a transformation that was likely induced by its firm association with terrestrial gastropods. The present study also documents that various ciliate lineages independently became commensals or parasites of various aquatic and terrestrial molluscs.

Ektaphelenchoides shiroodensis n. sp. (Rhabditida: Ektaphelenchinae) a new member of the genus

Nematology ◽  
2020 ◽  
Vol 22 (5) ◽  
pp. 493-503 ◽  
Author(s):  
Farzad Aliramaji ◽  
Ebrahim Pourjam ◽  
Majid Pedram
Keyword(s):  
New Species ◽  
Phylogenetic Analyses ◽  
Large Subunit ◽  
The Body ◽  
Body Region ◽  
Lsu Rdna ◽  
Similar Species ◽  
Mazandaran Province ◽  
Lateral Field ◽  
Posterior Body Region

Summary Ektaphelenchoides shiroodensis n. sp. is described and illustrated based upon morphological, morphometric and molecular data. It was recovered from the bark samples of a dead alder tree (Alnus sp.) from countryside around Shirood city, Mazandaran province, in the north of Iran. The new species is characterised by 768-985 μm long females, its lip region separated from the body contour by constriction, lateral field with three barely visible lines, forming two weak bands, 26-29 μm long stylet with wide lumen without conophore and basal swellings, excretory pore always at the level with median bulb, post-vulval uterine sac (PUS) 43-76 μm long, elongate conoid posterior body region ending to a long filiform part with pointed tip, males common with dorsally convex conical tail ending to a short narrower region with pointed tip, seven precloacal + cloacal + caudal papillae and arcuate spicules with wide condylus, blunt rostrum and simple end. Based upon the similar posterior body region (‘tail’) and comparable PUS length, the new species was compared to three known species, viz., E. attenuata, E. hunti and E. pini. Comparisons with the aforementioned species and similar species under the genus Seinura are discussed. The phylogenetic affinities of the new species, based upon two partial small and large subunit ribosomal DNA (SSU and LSU rDNA D2-D3) sequences, are discussed. Furthermore, several ektaphelenchid and seinurid species previously described from Iran were recovered in the present study, sequenced for their aforementioned genomic markers, and included in the phylogenetic analyses.

Morphology of Anomalocaris canadensis from the Burgess Shale

2014 ◽  
Vol 88 (1) ◽  
pp. 68-91 ◽  
Author(s):  
Allison C. Daley ◽  
Gregory D. Edgecombe
Keyword(s):  
Close Association ◽  
Dorsal Surface ◽  
Ventral Surface ◽  
The Body ◽  
Body Region ◽  
Morphological Description ◽  
Burgess Shale ◽  
Oral Cone ◽  
Stem Lineage ◽  
Posterior Body Region

Recent description of the oral cone of Anomalocaris canadensis from the Burgess Shale (Cambrian Series 3, Stage 5) highlighted significant differences from published accounts of this iconic species, and prompts a new evaluation of its morphology as a whole. All known specimens of A. canadensis, including previously unpublished material, were examined with the aim of providing a cohesive morphological description of this stem lineage arthropod. In contrast to previous descriptions, the dorsal surface of the head is shown to be covered by a small, oval carapace in close association with paired stalked eyes, and the ventral surface bears only the triradial oral cone, with no evidence of a hypostome or an anterior sclerite. The frontal appendages reveal new details of the arthrodial membranes and a narrower cross-section in dorsal view than previously reconstructed. The posterior body region reveals a complex suite of digestive, respiratory, and locomotory characters that include a differentiated foregut and hindgut, a midgut with paired glands, gill-like setal blades, and evidence of muscle bundles and struts that presumably supported the swimming movement of the body flaps. The tail fan includes a central blade in addition to the previously described three pairs of lateral blades. Some of these structures have not been identified in other anomalocaridids, making Anomalocaris critical for understanding the functional morphology of the group as a whole and corroborating its arthropod affinities.

scholarly journals An unusual suctorial montacutid bivalve from the deep Atlantic

2000 ◽  
Vol 80 (5) ◽  
pp. 827-834 ◽  
Author(s):  
J.A. Allen
Keyword(s):  
Benthic Invertebrate ◽  
Mantle Cavity ◽  
The Body ◽  
Ventral Margin ◽  
Dorsal Part ◽  
Internal Anatomy ◽  
Veliger Stage ◽  
First Time

The shell and internal anatomy of the montacutid bivalve Mysella verrilli is described for the first time. The species is remarkable in that the oesophagus has developed into a suctorial proboscis. This has been accompanied by the loss of the palps. In addition the gonads have been extended from the dorsal part of the body to form two gill-like extensions to which the reduced inner demibranchs attach along the postero–ventral margin. Mysella verrilli broods its young in the mantle cavity to the late veliger stage before releasing them. It is believed that the species is probably a suctorial ectoparasite on a soft-bodied benthic invertebrate.

Notes on the development of Paludina vivipara , with special reference to the urinogenital organs and theories of gasteropod torsion. (Preliminary note.)

1902 ◽  
Vol 69 (451-458) ◽  
pp. 291-294
Keyword(s):  
Special Reference ◽  
Early Stage ◽  
Mantle Cavity ◽  
The Body ◽  
Preliminary Note ◽  
Stage Of Development ◽  
Identical Position ◽  
First Time

Von Erlanger, in his work on the development of Paludina, made known for the first time the existence, at an early stage of development, of a rudimentary kidney belonging to the original left side of the body. He describes it as formed in the same manner as the definitive kidney, that is, as an evagination of the pericardial wall. According to him, at a fairly early stage it degenerates, together with the ingrowth of the mantle cavity, which formed its rudimentary duct, and a later evagination of the pericardial wall in an almost identical position gives rise to the gonad. This soon loses its connection with the pericardium and becomes vesicular, while an ingrowth of the mantle cavity, presumably the arrested kidney duct, grows towards it and finally fuses with it to form the gonaduct.

The reactions to carcinogens in the axolotl (Ambystoma mexicanum) in relation to the ‘regeneration field control’ hypothesis

Development ◽  
1971 ◽  
Vol 26 (3) ◽  
pp. 425-441
Author(s):  
Andrew J. Ingram
Keyword(s):  
Body Wall ◽  
Intradermal Injection ◽  
Ambystoma Mexicanum ◽  
The Body ◽  
Body Region ◽  
Initial Reaction ◽  
Wound Healing Response ◽  
Field Control ◽  
Control Hypothesis ◽  
Posterior Body Region

About 200 axolotls, between 5 and 21 months old, were treated in the body wall with carcinogens or control substances, by subcutaneous or intradermal injection, or by subcutaneous implantation. In response to an injection of dibenzanthracene in olive oil an initial reaction appeared within 13 days. This consisted of an epidermal proliferation and a subcutaneous infiltration of macrophages. The epidermis returned to normal after several weeks, but the subcutaneous response took 6 months to disappear. The initial reaction appeared to be, at least partially, a wound healing response; its regression could not have been due to regeneration field control as it occurred in the posterior body region. Following the disappearance of the initial reaction a secondary reaction of papilloma-like outgrowths arose between 7 and 20 months after injection. Of the axolotls surviving for a sufficient length of time, outgrowths arose in 14 out of 54 animals injected with dibenzanthracene and in 18 out of 57 sites injected with methylcholanthrene. These outgrowths had some features in common with the papillomata of mice, but none have yet progressed to carcinomata. In a group of axolotls injected in three different regions the frequency of outgrowths varied according to the sites; however, this was thought to be due to differences in the difficulty of injecting the three regions. Two tumours, a sarcoma and a hepatoma, arose in the course of these experiments, 3 and 2 years respectively after carcinogen treatment. From this it is suggested tentatively that tumour induction by polycyclic hydrocarbons in the axolotl may require a long latent period and involve a low tumour incidence; however, it is possible that at least one of the tumours was not induced by the treatment.

scholarly journals Myogenesis of Siboglinum Fiordicum Sheds Light on Body Regionalisation in Beard Worms (Siboglinidae, Annelida)

2021 ◽  
Author(s):  
Nadezhda Nikolaevna Rimskaya-Korsakova ◽  
Nadezda Karaseva ◽  
Timofei Pimenov ◽  
Hans Tore Rapp ◽  
Eve Southward ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
The Body ◽  
Body Region ◽  
Body Regions ◽  
Transmission Electron ◽  
Chaetopterus Variopedatus ◽  
Anterior Body ◽  
Longitudinal Muscles ◽  
Posterior Body Region

Abstract BackgroundMany annelids, including well-studied species such as Platynereis, show similar structured segments along their body axis (homonomous segmentation). However, numerous annelid species diverge from this pattern and exhibit specialised segments or body regions (heteronomous segmentation). Recent phylogenomic studies and paleontological findings suggest that a heteronomous body architecture may represent an ancestral condition in Annelida. To better understand the segmentation within heteronomous species we describe the myogenesis and mesodermal delineation of segments in Siboglinum fiordicum during development. ResultsEmploying confocal and transmission electron microscopy we show that the somatic circular musculature lies inside the longitudinal musculature and is predominantly developed at the anterior end of the larva. The longitudinal musculature consists of four separate strands at the ventral, dorsal, and ventrolateral body sides. Posteriorly, the longitudinal strands form a continuous layer. Our application of transmission electron microscopy allows us to describe the developmental order of the non-muscular septa. The first septum to form is supported by thick bundles of longitudinal muscles and separates the body into an anterior and a posterior region. The second group of septa to develop further divides the posterior body region (opisthosoma) and is supported by developing circular muscles. At the late larval stage, a septum reinforced by circular muscles divides the anterior body region into a forepart and a trunk segment. The remaining septa and their circular muscles form one by one at the very posterior end of the opisthosoma. Functionally, the prominent ventrolateral longitudinal muscles in the larva are proposed to drive the search movements of the head, while the anterior circular muscles and the posterior continuous layers of longitudinal muscles support the burrowing behaviour of the larva.ConclusionsThe heteronomous Siboglinum lacks the strict anterior to posterior sequence of segment formation as it is found in the most studied annelid species. Instead, the first septum divides the body into two body regions, before segments are layed down in first the posterior opisthosoma and then in the anterior body, respectively. Similar pattern of segment formation is described for the heteronomous chaetopterid Chaetopterus variopedatus and may represent an ancestral segmentation process in Annelida.

Nematodes associated with the invasive quagga mussel (Dreissena rostriformis bugensis) in the Colorado River Aqueduct reservoirs, southern California, USA

Nematology ◽  
2012 ◽  
Vol 14 (7) ◽  
pp. 827-837 ◽  
Author(s):  
Nicole J. Reid ◽  
Oleksandr Holovachov ◽  
Michael A. Anderson
Keyword(s):  
Nematode Species ◽  
Mantle Cavity ◽  
Nematode Community ◽  
Quagga Mussel ◽  
Symbiotic Relationship ◽  
Free Living ◽  
Quagga Mussels ◽  
Dreissena Rostriformis Bugensis ◽  
Periphyton Community ◽  
First Time

The nematode community inhabiting the mantle cavity of quagga mussels, Dreissena rostriformis bugensis, in Copper Basin Reservoir and Lake Skinner was quantified and compared for the first time with the nematode community from the periphyton surrounding the mussels. Nematode species inhabiting the mantle cavity were also found in the periphyton, while the periphyton community always contained more species than the mantle cavity. Chromadorina bioculata was the dominant species in the mantle cavity and periphyton community in Lake Skinner and Copper Basin Reservoir. Our results suggest that nematodes found inside the mantle cavity of the mollusc do not have obligate symbiotic relationship with quagga mussels, but that they are free-living, entering from the periphyton community into the mantle cavity of the mussel, exhibiting neutralism.

scholarly journals Two new species of Euplotes with cirrotype-9, Euplotes foissneri sp. nov. and Euplotes warreni sp. nov. (Ciliophora, Spirotrichea, Euplotida), from the coasts of Patagonia: implications from their distant, early and late branching in the Euplotes phylogenetic tree

2020 ◽  
Author(s):  
Alessandro Valbonesi ◽  
Graziano Di Giuseppe ◽  
Adriana Vallesi ◽  
Pierangelo Luporini
Keyword(s):  
Body Size ◽  
Body Length ◽  
Phylogenetic Analyses ◽  
Small Body ◽  
Dorsal Surface ◽  
The Body ◽  
Body Region ◽  
Rrna Gene ◽  
Small Subunit Rrna

Two new Euplotes species have been isolated from cold shallow sandy sediments of the extreme Southern Chilean coasts: Euplotes foissneri sp. nov., from a low-salinity site at Puerto Natales on the Pacific coast, and Euplotes warreni sp. nov., from a marine site at Punta Arenas on the Atlantic coast. Euplotes foissneri has a medium body size (53×36 µm in vivo), a dorsal surface marked by six prominent ridges, a double dargyrome, six dorsal and two ventrolateral kineties, a buccal field extending to about 3/4 of the body length, an adoral zone composed of 28–32 membranelles, and nine fronto-ventral, five transverse and two or three caudal cirri. The bulky, hook-, horseshoe- or 3-shaped macronucleus is associated with one sub-spherical micronucleus. The central body region hosts taxonomically unidentified endosymbiotic eubacteria. Euplotes warreni has a small body size (39×27 µm in vivo), a smooth dorsal surface marked by three deep grooves, a double dargyrome, four dorsal and two ventrolateral kineties, a buccal field extending to about 2/3 of the body length, an adoral zone composed of 23–25 adoral membranelles, and nine fronto-ventral, five transverse and three caudal cirri. The macronucleus is hook- or C-shaped and associated with one spherical micronucleus. Endosymbiotic bacteria belonging to the genus Francisella reside preferentially in the anterior cell region. Both species lack the fronto-ventral cirrus numbered ‘V/2’, whereby their cirrotype-9 conforms to the so-called ‘pattern I’, which is the basic distinctive trait of the genus Euplotopsis Borror and Hill, 1995. Phylogenetic analyses of small subunit rRNA gene sequences, however, classify E. warreni into its own early branching clade and E. foissneri into a late branching clade. This indicates a polyphyletic nature and taxonomic inconsistency of the genus Euplotopsis, which was erected to include Euplotes species with cirrotype-9 pattern I.

scholarly journals How zebrafish turn: analysis of pressure force dynamics and mechanical work

2020 ◽  
Vol 223 (16) ◽  
pp. jeb223230
Author(s):  
Robin Thandiackal ◽  
George V. Lauder
Keyword(s):  
The Body ◽  
Mechanical Work ◽  
Body Region ◽  
Fish Locomotion ◽  
Force Dynamics ◽  
Negative Work ◽  
Image Velocimetry ◽  
Work Done ◽  
Swimming Kinematics ◽  
Posterior Body Region

ABSTRACTWhereas many fishes swim steadily, zebrafish regularly exhibit unsteady burst-and-coast swimming, which is characterized by repeated sequences of turns followed by gliding periods. Such a behavior offers the opportunity to investigate the hypothesis that negative mechanical work occurs in posterior regions of the body during early phases of the turn near the time of maximal body curvature. Here, we used a modified particle image velocimetry (PIV) technique to obtain high-resolution flow fields around the zebrafish body during turns. Using detailed swimming kinematics coupled with body surface pressure computations, we estimated fluid–structure interaction forces and the pattern of forces and torques along the body during turning. We then calculated the mechanical work done by each body segment. We used estimated patterns of positive and negative work along the body to evaluate the hypothesis (based on fish midline kinematics) that the posterior body region would experience predominantly negative work. Between 10% and 20% of the total mechanical work was done by the fluid on the body (negative work), and negative work was concentrated in the anterior and middle areas of the body, not along the caudal region. Energetic costs of turning were calculated by considering the sum of positive and negative work and were compared with previous metabolic estimates of turning energetics in fishes. The analytical workflow presented here provides a rigorous way to quantify hydrodynamic mechanisms of fish locomotion and facilitates the understanding of how body kinematics generate locomotor forces in freely swimming fishes.

Skin-digging tanaids: the unusual parasitic behaviour of Exspina typica in Antarctic waters and worldwide deep basins

2011 ◽  
Vol 23 (4) ◽  
pp. 343-348 ◽  
Author(s):  
Maria Chiara Alvaro ◽  
Magdalena Błażewicz-Paszkowycz ◽  
Niki Davey ◽  
Stefano Schiaparelli
Keyword(s):  
Body Wall ◽  
Ross Sea ◽  
Body Cavity ◽  
The Body ◽  
Free Living ◽  
Common Life ◽  
Life Styles ◽  
Antarctic Waters ◽  
The Antarctic ◽  
First Time

AbstractThe order Tanaidacea includes over 1000 species which are mainly free-living or tube-dwelling detritivores. Exspina typica Lang, 1968 represents an exception to these common life styles, having being found in the intestine and body cavity of deep sea holothuroids. The 2008 New Zealand ‘IPY-CAML Cruise’ held in the Ross Sea collected several deepwater holothuroids that were observed to carry specimens of E. typica inside their coelomic cavity. A clear interpretation of this association was hence possible. Even if E. typica shows slight adaptations to a parasitic life style, the tanaids were found to actively ‘dig’ into the host's skin, grasping tissue with their claws and producing tunnels in the body wall. It is therefore possible to clearly define this association, which is here reported from the Antarctic for the first time, as parasitism.

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