Anemonefish are better taxonomists than humans.

The symbiosis between giant sea anemones, algae of the family Symbiodiniaceae, and anemonefish is an iconic example of a mutualistic trio1,2. Molecular analyses have shown that giant sea anemones hosting anemonefish belong to three clades: Entacmaea, Stichodactyla, and Heteractis3,4,5 (Figure 1A). Associations among 28 species of anemonefish and 10 species of giant sea anemone hosts are complex. Some fish species are highly specialized to only one anemone species (e.g., Amphiprion frenatus with Entacmaea quadricolor), whereas others are more generalist (e.g., Amphiprion clarkii)1,2,6. Reasons for host preferences are obscured, among other things, by the lack of resolution in the giant sea anemone phylogeny. Here, we generated a transcriptomic dataset from 55 sea anemones collected from southern Japan to reconstruct these phylogenetic relationships. We observed that the bubble-tip sea anemone E. quadricolor, currently considered a single species, can be separated into at least four cryptic lineages (A-D). Surprisingly, these lineages can be precisely distinguished by observing their association with anemonefish: A. frenatus only associates with lineage D, whereas A. clarkii lives in the other three lineages.

Evaluation of motion artifacts reduction software that compensate for respiratory movements in the craniocaudal direction during abdominal cone-beam computed tomography.

We acquired cone-beam computed tomography (CBCT) images of a locally made contrast-enhanced hepatic artery phantom under various conditions, both with the phantom still, and while moving it from the cranial to the caudal position. All the motion CBCT images were processed with and without motion artifacts reduction software (MARS). We calculated some quantitative similarity indexes between the still CBCT images (no-motion) and the motion CBCT images both processed with MARS (MARS ON) and without MARS (MARS OFF). In addition, the vessel signal values under the same movement conditions of the MARS ON/OFF and no-motion were evaluated. All quantitative similarity indexes between MARS ON and no-motion were significantly higher than between MARS OFF and no-motion in all movement conditions (p < 0.01). The vessel signal values were higher in MARS ON than in MARS OFF (p < 0.01) and closer to no-motion in all movement conditions.

Low Radiation Protocol for Intraoperative Robotic C-Arm Can Enhance Adolescent Idiopathic Scoliosis Deformity Correction Accuracy and Safety.

STUDY DESIGN: Retrospective case-series study. OBJECTIVES: To assess (1) low cone beam CT (CBCT) mediated intraoperative navigation to limit radiation exposure without compromising surgical accuracy, and (2) the potential of intraoperative C-arm CBCT navigation to augment pedicle screw (PS) placement accuracy in AIS surgery compared to pre-surgery CT-based planning. METHODS: The first part involved a prospective phantom study, comparing radiation doses for conventional CT, and standard (6sDCT) and a low dose (5sDCT) Artis Zeego®-imaging. Next, 5sDCT- and 6sDCT-navigation were compared on PS accuracy and radiation exposure during AIS correction. The final part compared surgical AIS deformity correction through intraoperative 5sDCT navigation to a matched cohort treated using conventional pre-surgery CT-scans for navigation. Outcome parameters included operation time, skin dose (SD), dose area product (DAP), intraoperative blood loss, postoperative complications, and PS deviation rates. RESULTS: The phantom study demonstrated a reduction in radiation for the 5sDCT protocol. Moreover, 5sDCT-imaged patients (n = 15) showed a significantly lower SD (-27.41%) and DAP (-30.92%), without compromising PS accuracy compared with 6sDCT-settings (n = 15). Finally, AIS correction through intraoperative CBCT C-arm navigation (n = 27) significantly reduced screw deviation rates (6.83% versus 10.75%, P = .016) without increasing operation times, compared with conventional CT (n = 37). CONCLUSIONS: Intraoperative navigation using a CBCT C-arm system improved the accuracy of PS insertion and reduced surgery time. Moreover, it reduced radiation exposure compared with conventional CT, which was further curtailed by adapting the low-dose 5sDCT protocol. In short, our study highlights the benefits of intraoperative CBCT navigation for PS placement in AIS surgery.

Carcinoecium-Forming Sea Anemone Stylobates calcifer sp. nov. (Cnidaria, Actiniaria, Actiniidae) from the Japanese Deep-Sea Floor: A Taxonomical Description with Its Ecological Observations.

Here we describe Stylobates calcifer sp. nov. (Cnidaria, Actiniaria, Actiniidae), a new carcinoecium-forming sea anemone from the deep-sea floor of Japan. Stylobates produces a carcinoecium that thinly covers the snail shells inhabited by host hermit crabs Pagurodofleinia doederleini. The new species is distinct from other species by the shape of the marginal sphincter muscle, the distribution of cnidae, the direction of the oral disk, and host association. The species' novelty is supported by the data of its mitochondrial genes 12S, 16S, and COIII and nuclear genes 18S and 28S. Also, we conducted behavioral observation of this new species, focusing on the feeding behavior and interaction with the specific host hermit crab. Our observations suggest that this sea anemone potentially feeds on the suspended particulate organic matter from the water column or the food residuals of hermit crabs. When the host's shell changed, intensive manipulation for transference of S. calcifer sp. nov. was recorded. However, although the hermit crab detached and transferred the sea anemone to the new shell after shell change, the sea anemone did not exhibit active or cooperative participation. Our data suggest that the sea anemone may not produce a carcinoecium synchronously to its host's growth, contrary to the anecdotal assumption about carcinoecium-forming sea anemones. Conversely, the host hermit crab's growth may not depend entirely on the carcinoecium produced by the sea anemone. This study is perhaps the first observation of the behavioral interaction of the rarely studied carcinoecium-forming mutualism in the deep sea.

Description of the second species of Synhalcurias Carlgren, 1914, Synhalcurias kahakui sp. nov. (Actiniaria: Actinernidae) with redescription of S. elegans (Wassilieff, 1908).

We describe a new sea anemone species, Synhalcurias kahakui sp. nov., from specimens collected off Otouto-jima and Amami-oshima islands in July 2016 and May 2019. respectively. These sea anemones were identified as belonging to family Actinernidae due to their many endocoelic perfect mesenteries and identified as belonging to the genus Synhalcurias Carlgren, 1914 because they have an oral disc without any developed lobes. Though this genus presently accommodates only one species, Synhalcurias elegans (Wassilieff, 1908), our specimens are smaller than the aforementioned species, have fewer mesenteries, lack nematocyst batteries on the column, and have two types of microbasic p-mastigophores on the mesenterial filaments. These specimens are described as Synhalcurias kahakui sp. nov. In view of the new species, the diagnosis of genus Synhalcurias is revised. In addition, we redescribe S. elegans based on newly specimens collected from Japan.

Redescription of Synactinernus flavus for the First Time after a Century and Description of Synactinernus churaumi sp. nov. (Cnidaria: Anthozoa: Actiniaria).

Two species of Synactinernus sea anemones were found in Japanese waters. Synactinernus flavus Carlgren, 1918, the only described species of this genus, is rediscovered from off the Goto Islands a century after the original description. Synactinernus flavus was once synonymized with Isactinernus quadrilobatus Carlgren, 1918; however, we show that, based on morphological (including examination of type specimens) and molecular (using nuclear 18S rDNA) evidence, these species are completely different. The other species, Synactinernus churaumi sp. nov., was found off Ishigaki Island and Okinawa Island by a remotely operated vehicle (ROV), and had been kept for 15 years in a tank at the Okinawa Churaumi Aquarium. There are clear differences between these two species; therefore, we describe the second species and revise the diagnosis of Synactinernus.

Phylogenetic relationships among the clownfish-hosting sea anemones.

The clownfish-sea anemone symbiosis has been a model system for understanding fundamental evolutionary and ecological processes. However, our evolutionary understanding of this symbiosis comes entirely from studies of clownfishes. A holistic understanding of a model mutualism requires systematic, biogeographic, and phylogenetic insight into both partners. Here, we conduct the largest phylogenetic analysis of sea anemones (Order Actiniaria) to date, with a focus on expanding the biogeographic and taxonomic sampling of the 10 nominal clownfish-hosting species. Using a combination of mtDNA and nuDNA loci we test (1) the monophyly of each clownfish-hosting family and genus, (2) the current anemone taxonomy that suggests symbioses with clownfishes evolved multiple times within Actiniaria, and (3) whether, like the clownfishes, there is evidence that host anemones have a Coral Triangle biogeographic origin. Our phylogenetic reconstruction demonstrates widespread poly- and para-phyly at the family and genus level, particularly within the family Stichodactylidae and genus Stichodactyla, and suggests that symbioses with clownfishes evolved minimally three times within sea anemones. We further recover evidence for a Tethyan biogeographic origin for some clades. Our data provide the first evidence that clownfish and some sea anemone hosts have different biogeographic origins, and that there may be cryptic species of host anemones. Finally, our findings reflect the need for a major taxonomic revision of the clownfish-hosting sea anemones.

First Detailed Record of Symbiosis Between a Sea Anemone and Homoscleromorph Sponge, With a Description of Tempuractis rinkai gen. et sp. nov. (Cnidaria: Anthozoa: Actiniaria: Edwardsiidae).

A new species in a new genus of sea anemone, Tempuractis rinkai gen. et sp. nov., was discovered at several localities along the temperate rocky shores of Japan. The new species is approximately 4 mm in length and has been assigned to family Edwardsiidae, because it has eight macrocnemes, lacks sphincter and basal muscles, and possesses rounded aboral end. The sea anemone, however, also has a peculiar body shape unlike that of any other known taxa. This new species resembles some genera, especially Drillactis and Nematostella, in smooth column surface without nemathybomes or tenaculi, but is distinguishable from them by several morphological features: the presence of holotrichs and absence of nematosomes. Furthermore, this edwardsiid species exhibits a peculiar symbiotic ecology with sponges. Therefore, a new genus, Tempuractis, is proposed for this species. In the field, T. rinkai sp. nov. was always found living inside homosclerophorid sponge of the genus Oscarella, which suggests a possible obligate symbiosis between Porifera and Actiniaria. The benefit of this symbiosis is discussed on the basis of observations of live specimens, both in the aquarium and field. This is the first report of symbiosis between a sea anemone and a homoscleromorph sponge.

The 'Antenna Balloon Anemone' Found in the Seto Inland Sea: New Genus and Species of Sea Anemone, Antennapeachia setouchi (Cnidaria, Actinaria, Haloclavidae).

In the present study, we report the identification of a sea anemone, Antennapeachia setouchi, collected in the Seto Inland Sea, which represents a new genus and new species. This new species has unusual tentacle and mesenterial arrangements that have not been observed in other species of Haloclavidae. There are 12 regular marginal tentacles and two 'antenna tentacles,' with the latter always rising upward and located on the oral disk near the mouth; the species is also characterized by its peculiar mesenterial pairs, consisting of a macrocneme and a microcneme. Furthermore, this species shows an interesting behavior: it can inflate its body like a balloon, lift above the seafloor, and drift with the sea current. The presence of a single, strong siphonoglyph, physa-like aboral end, and the lack of sphincter muscle classify this sea anemone within Haloclavidae. It resembles Peachia species, but cannot be classified in this genus as the new species has two pairs of mesenteries, consisting of a macrocneme and a microcneme, and irregular antenna tentacles. Therefore, we propose a new genus Antennapeachia to accommodate this species.

Acanthopleuribacter pedis gen. nov., sp. nov., a marine bacterium isolated from a chiton, and description of Acanthopleuribacteraceae fam. nov., Acanthopleuribacterales ord. nov., Holophagaceae fam. nov., Holophagales ord. nov. and Holophagae classis nov. in the phylum 'Acidobacteria'.

Strain FYK2218(T) was isolated from a specimen of the chiton Acanthopleura japonica, which had been collected from a beach on the Boso peninsula in Japan. Phylogenetic analyses based on 16S rRNA gene sequences revealed that the strain belonged to the phylum 'Acidobacteria'. The most closely related type strains to strain FYK2218(T) were Holophaga foetida TMBS4(T) (83.6 % 16S rRNA gene sequence similarity) and Geothrix fermentans H-5(T) (83.6 %) in subdivision 8 of the 'Acidobacteria'. Cells of FYK2218(T) were motile, rod-shaped, Gram-negative, mesophilic and strictly aerobic. The G+C content of the strain was 56.7 mol%. The strain had isoprenoid quinones MK-6 and MK-7 as major components. Major fatty acids of the strain were iso-C(15 : 0), iso-C(17 : 0), C(16 : 0) and C(20 : 5)omega3c (cis-5,8,11,14,17-eicosapentaenoic acid). From the taxonomic data obtained in this study, it is proposed that the new marine isolate be placed into a novel genus and species named Acanthopleuribacter pedis gen. nov., sp. nov. within the new family, order and class Acanthopleuribacteraceae fam. nov., Acanthopleuribacterales ord. nov. and Holophagae classis nov. The family Holophagaceae fam. nov. is also described. The type strain of Acanthopleuribacter pedis is FYK2218(T) (=NBRC 101209(T) =KCTC 12899(T)).

Pseudovibrio ascidiaceicola sp. nov., isolated from ascidians (sea squirts).

Two bacterial strains, F423T and F10102, were isolated from two ascidians, Polycitor proliferus and Botryllidae sp., respectively, which were collected from a beach on the Boso peninsula in Japan. Cells of both isolates were motile, rod-shaped and formed star-shaped aggregates in the early stage of exponential growth, but were coccoid in stationary growth phase. The results of 16S rRNA gene sequence analysis, fatty acid analysis, DNA-DNA hybridization experiments and physiological and biochemical tests indicated that the two strains were members of a novel species of the genus Pseudovibrio for which the name Pseudovibrio ascidiaceicola sp. nov. is proposed. The type strain is F423T (=NBRC 100514T=IAM 15084T=DSM 16392T=KCTC 12308T).

Identification of a new member of the GLWamide peptide family: physiological activity and cellular localization in cnidarian polyps.

KPNAYKGKLPIGLWamide, a novel member of the GLWamide peptide family, was isolated from Hydra magnipapillata. The purification was monitored with a bioassay: contraction of the retractor muscle of a sea anemone, Anthopleura fuscoviridis. The new peptide, termed Hym-370, is longer than the other GLWamides previously isolated from H. magnipapillata and another sea anemone, A. elegantissima. The amino acid sequence of Hym-370 is six residues longer at its N-terminal than a putative sequence previously deduced from the cDNA encoding the precursor protein. The new longer isoform, like the shorter GLWamides, evoked concentration-dependent muscle contractions in both H. magnipapillata and A. fuscoviridis. In contrast, Hym-248, one of the shorter GLWamide peptides, specifically induced contraction of the endodermal muscles in H. magnipapillata. This is the first case in which a member of the hydra GLWamide family (Hym-GLWamides) has exhibited an activity not shared by the others. Polyclonal antibodies were raised to the common C-terminal tripeptide GLWamide and were used in immunohistochemistry to localize the GLWamides in the tissue of two species of hydra, H. magnipapillata and H. oligactis, and one species of sea anemone, A. fuscoviridis. In each case, nerve cells were specifically labeled. These results suggest that the GLWamides are ubiquitous among cnidarians and are involved in regulating the excitability of specific muscles.