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A new stubby-root nematode belonging to the Trichodorus sparsus complex was found in association with serious damage to Hill’s Yew hedges (Taxus x media ´Hillii´) in Oslo in 2017, characterised by chlorosis, wilting and loss of needles. T. hellalae n. sp. is about 800 μm long with medium-sized onchiostyle (55 μm, average), characterized in male by two ventromedian cervical papillae located beyond the onchiostyle region and with the secretory excretory pore (SE-pore) in between, in most type specimens, three ventromedian precloacal supplements with the posteriormost one opposite the anterior end of spicule manubrium and spicules 40 μm long (average) with widened manubrium, gradually tapered to a narrower blade without ornamentation of striae or bristles, but showing a minor indentation at level of posterior border of capsule of suspensor muscles. Gubernaculum with thickened keel-like posterior end and a thickened refractive anterior border. Females are characterised by a short pear-shaped vagina, less than 1/3rd of corresponding body width and very small rounded triangular vaginal sclerotized pieces in longitudinal optical section and vulva pore-like in ventral view; on each body side one sublateral body pore at about 3.5 body width anterior to vulva and one postadvulvar body pore. According to D2-D3 analyses, the Trichodorus hellalae n. sp. sequences are embedded in a maximally supported clade with several T. variabilis lineages. However, morphological and molecular species delimitation both support Trichodorus hellalae n. sp. as being a new species. Therefore, T. variabilis now appears to in fact consists of several cryptic species.

Organisms can uptake minerals, shape them in different forms and generate teeth, skeletons or shells that support and protect them. Mineral uptake, trafficking and nucleation are tightly regulated by the biomineralizing cells through networks of specialized proteins. Specifically, matrix metalloproteases (MMPs) digest various extracellular substrates and allow for mineralization in the vertebrates' teeth and bones, but little is known about their role in invertebrates' systems. The sea urchin embryo provides an excellent invertebrate model for genetic and molecular studies of biomineralization. MMP inhibition prevents the growth of the calcite spicules of the sea urchin larval skeleton, however, the molecular mechanisms and genes that underlie this response are not well understood. Here we study the spatial expression and regulation of two membrane type MMPs that were found to be occluded in the sea urchin spicules, Pl-MmpL7 and Pl-MmpL5, and investigate the function of Pl-MmpL7 in skeletogenesis. The inhibition of MMPs does not change the volume of the calcium vesicles in the skeletogenic cells. The expression of Pl-MmpL7 and Pl-MmpL5 is regulated by the Vascular Endothelial Growth Factor (VEGF) signaling, from the time of skeleton initiation and on. The expression of these genes is localized to the subsets of skeletogenic cells where active spicule growth occurs throughout skeletogenesis. Downregulation of Pl-MmpL7 expression delays the growth of the skeletal rods and in some cases, strongly perturbs skeletal shape. The localized expression of Pl-MmpL7 and Pl-MmpL5 to the active growth zone and the effect of Pl-MmpL7 perturbations on skeletal growth, suggest that these genes are essential for normal spicule elongation in the sea urchin embryo.

The nematode parasite Neoascarophis mariae was collected from the intestine of Parupeneus forsskali and Mulloidichthys flavolineatus from the Red Sea in Egypt and was described using both light and scanning electron microscopy. It is mainly characterized by the presence of four submedian labia surrounded the oral aperture in the outer side, two sublabia and two pseudolabia in the inner side, rounded cephalic end, and short vestibule in both sexes. The females vulva is located near the posterior end of the body, their oval uterine eggs have a smooth surface devoid of filaments. Males have bifurcated deirids, a large left spicule (85–425 µm) with a tapered tip, and a short right spicule (50–181 µm) with a broad and rounded tip.

This study was aimed at describing two (2) intestinal nematodes from naturally infected native breed of goats (Capra hircus) in Bangladesh, identified as Oesophagostomum columbianum (Curtice, 1890) Stossich 1899 and Haemonchus contortus (Rudolphi, 1803) Cobb, 1898. The identification was made based on morphometric features and was confirmed by amplifying internal transcribed spacer (ITS) and cytochrome c oxidase (cox1) gene. Well-developed lateral alae, distinct cervical papillae anteriorly to esophageal expansion, and male spicule length (0.73-0.79 mm,n=2) were characteristically observed in O. columbianum. At the same time, male spicule length (0.40-0.46 mm,n=2) and position of female vulvar flap (4.30-4.54 mm from posterior end,n=3) were observed in H. contortus. DNA sequence homology of the ITS and cox1 gene of both specimens revealed the same results, showing similarity to the GenBank sequences of O. columbianum (GenBank No. KC715827; JX188470) and H. contortus (GenBank No. KJ724377; HQ389229). Phylogenetic analysis computed by maximum livelihood (ML) from the ITS nucleotide sequences revealed that the O. columbianum and H. contortus isolates identified in this study were clustered in the same clade with isolates from China and Iran, respectively. This study, for the first time, illustrates the characteristics of O. columbianum and H. contortus in Bangladesh, combining both morphological and molecular data. The universal primer-based polymerase chain reaction (PCR) protocol could be an economical and efficient option for researchers from poor resource settings for precise identification of nematodes. The information generated in this study may contribute to formulating effective control strategies against these nematodes.

Illustrated descriptions of two new free-living nematodes found in the Cấm River mouth in Vietnam are given. Eumonhystera rivalis sp. n. is morphologically similar to E. dispar (Bastian, 1865); E. sudanensis Zeidan et al., 1989; and E. maxima Gagarin, 1996, but differs by the presence of biocrystal-like bodies, amphid fovea located closer to anterior body end, and longer cephalic setae. Daptonema borealis sp. n. is similar to D. vicinus (Riemann, 1966); D. aquedulcis (Gagarin, 1987); and D. salinae Gagarin, Gusakov, 2014, but has shorter body, shorter cephalic setae, and spicule size.

A new species of entomopathogenic nematodes, Steinernema sandneri n. sp., was recovered by baiting from Poland. Its morphological traits indicate that the new species is a member of the feltiae-kraussei group. A body length of 843 (708–965) μm, a more anterior position of excretory pore (56 μm), and the lower D% value (40 vs > 46) discriminate this species from most of the other group members. The first-generation males of S. sandneri n. sp. can be distinguished from the other clade members by a 60 μm long spicule, a relatively long gubernaculum (GS% = 79), and the position of the excretory pore (80 μm). Phylogenetic analysis of the ITS rDNA, D2D3 of 28 S rDNA, and cox1 sequences confirmed that S. sandneri n. sp. is a new species of the feltiae-kraussei group, closely related to S. kraussei and S. silvaticum.

Summary During surveys for stubby root nematodes in the natural vegetation of California, Oregon and Washington, USA, three known species, viz., Trichodorus californicus, T. intermedius and T. obscurus were recovered together with ten unidentified Trichodorus species. The three known and one new species were studied using an integrated approach. Trichodorus pseudoaequalis n. sp. is characterised by a medium-sized body about 800 μm long on average, male with two ventromedian cervical papillae anterior to secretory-excretory pore and three precloacal supplements all located anterior to the retracted spicules; spicules 39 μm long (average), slightly ventrally curved, more so in head region and blade with slight indentation mid-way and striation more pronounced in posterior half. Females possess a rather short (average 33% of corresponding body diam.) pear-shaped vagina with small vaginal sclerotised pieces (ca 1.5 μm long), rounded triangular in shape, obliquely orientated and close together; one pair of sublateral body pores anterior (about four vulval body diam.) to vulva and one pair of post-advulvar sublateral body pores. Trichodorus pseudoaequalis n. sp. differs from the most similar species, T. aequalis, in male characters like general spicule shape and ornamentation and in the position of the dorsal pharyngeal gland nucleus in both sexes (at same level of posterior ventrosublateral pair vs clearly separated). The phylogenetic relationships of the recovered species were reconstructed using the ITS2 rRNA and the D2-D3 expansion segments of 28S rRNA gene sequences.

A diplogastrid nematode species was isolated from a termite-associated tenebrionid beetle, Ziaelas formosanus, collected from several localities in Taiwan. The new species shares a characteristic feeding structure, i.e., an extremely long and thin stoma with two genera, Rhabditolaimus and Mehdinema. However, the new species has highly characteristic male and female reproductive system, i.e., arrangement of male genital papillae, spicule and gubernaculum morphologies, and presence of female receptaculum seminis, that are similar to those of Acrostichus. A molecular phylogenetic analysis based on near-full-length small subunit and D2-D3 expansion segments of large subunit of ribosomal RNA gene sequences suggested that the species belongs to Acrostichus. The highly derived feeding characters of the new species accentuates the plasticity of the feeding structures of diplogastrid nematodes. In addition to the species description, the generic characters of Acrostichus are emended, and a list of the species in the genus is provided.

International audience; Based on light and scanning electron microscopical studies, a new nematode parasite, Paracapillaria (Paracapillaria) gastrica n. sp. (Capillariidae), is described from the stomach of the marine fish (variegated lizardfish) Synodus variegatus (Lacépède) (Aulopiformes: Synodontidae) from off New Caledonia. This species is mainly characterised by the length of the spicule (267 µm), the proximal spicule end expanded to form a conspicuous folded, lobular rim, the presence of a well-developed caudal bursa supported by two lateral projections (rays) not adhering to the posterior border of body and by the size of eggs (54-60 9 24-27 µm) with non-protruding polar plugs. Paracapillaria gastrica n. sp. is the first known capillariid species parasitic in a host belonging to the fish order Aulopiformes and the first species of this genus reported from fishes in New Caledonian waters and the South Pacific Ocean.

Four new species of Rugopharynx Monnig, 1927 are described from macropodid marsupials in Australia, some identified initially using molecular methods. Rugopharynx thetidis n. sp. from Thylogale thetis (Lesson) was initially included within R. sigma Chilton, Beveridge & Andrews, 1993 but was identified as being distinctive using molecular methods and is differentiated morphologically from R. sigma by the more anterior position of the deirid and by the distinctive curvature of the spicule tips. Rugopharynx thylogale n. sp., also from Thylogale thetis, is distinguished by the extreme elongation of the dorsal lobe of the bursa and spicule length (1.07-1.23 mm). Rugopharynx solitarius n. sp., again from Thylogale thetis, was initially included within Rugopharynx zeta (Johnston & Mawson, 1939) but differs morphologically in the features of the bursa. Rugopharynx disiunctus n. sp. from Macropus fuliginosus (Desmarest) was initially included within Rugopharynx rho Beveridge & Chilton, 1999 but was identified as distinctive based on DNA sequence differences. The new species differs from R. rho in the pattern of striations on the buccal capsule and in the lengths of the spicules. Additional records of species of Rugopharyx in M. fuliginosus in Western Australia are provided.

Nematode spicules vary in shape and size even between closely related species and, therefore, constitute key characters in nematode taxonomy for distinguishing between species. Spicules are seldom measured on fresh specimens, but rather at some time after extraction from culled hosts and after a period of preservation of the worms in chemical fixatives or by freezing. We carried out two experiments to assess the effects of freezing in Hanks’ balanced salt solution, 70% or 80% ethanol and 10% formalin (both of the latter at room temperature and after storage at −80°C) on spicule length of Heligmosomoides bakeri at two time intervals after extraction from mice (Experiment 1, one and four weeks; Experiment 2, one and four months). In Experiment 1, no significant differences were detected, although there was some variation between treatments and over time. In Experiment 2, spicule length varied significantly between treatments and over time, the greatest shrinkage being in 80% ethanol and the least in 10% formalin. However, overall variation in spicule length was very limited, accounting for no more than 5.03% change in length over time and 4.95% between treatments at any of the periods of assessment. Therefore, while whole nematodes can shrivel and shrink in preservatives, making many measurements unreliable, our data indicated that spicule lengths are very little changed by preservation techniques over time, and so spicule length remains as a reliable taxonomic character.

Introduction The coccyx is well-known to be a highly variable structure considering its morphology. To our knowledge, the relationship between the coccygeal types and other morphological features has not been studied yet. In addition to the interrelations among morphological parameters, this study investigated the morphology and morphometry of coccyx more extensively in the adult Turkish population using computerized tomography images. Methods Five hundred subjects who underwent pelvic computerized tomography were included in this study. In addition to coccyx type and the counts of coccygeal vertebrae and segments, the presence of coccygeal deviation, sacrococcygeal joint (SCJ) fusion, SCJ subluxation, intercoccygeal joint (ICJ) fusion, and coccygeal spicule were evaluated. The coccygeal length, sacrococcygeal angle, and intercoccygeal angle were measured on the digital workstation. The findings were subjected to statistical analyses. Results The coccygeal vertebra count ranged between three to five, with an average of 4.04 ± 0.48. The range of coccygeal segment count was between one and five, with an average of 2.53 ± 1.02. ICJ fusion in any segment, SCJ fusion, and SCJ subluxation were identified in 397 subjects (79.4%), 343 subjects (68.6%), and 17 subjects (3.4%), respectively. The coccyx types from the most common to the least common were as follows: type 2, type 1, type 3, type 4, and type 5. Coccygeal deviation to the left side was observed in 71 subjects (14.2%), while coccygeal deviation to the right side was observed in 61 subjects (12.2%). A coccygeal spicule was identified in 73 subjects (14.6%). The subjects’ mean age demonstrated no significant difference considering the ICJ fusion (p=0.271), SCJ subluxation (p=0.51), coccygeal spicule (p=0.337), features of coccygeal deviation (p=0.83), and coccyx types (p=0.11). The subjects with SCJ fusion (50.7 ± 18.3 years) were significantly older than the subjects without SCJ fusion (46.5 ± 18.5 years) (p=0.016). The differences between the coccyx types considering the rate of SCJ fusion (p=0.002), ICJ fusion (p=0.04), and spicule presence (p

Made available in DSpace on 2022-04-29T08:46:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-12 A new nematode species, Rhabdochona (Rhabdochona) fuscovaria sp. n. (Rhabdochonidae), is described based on specimens collected from the stomach of the snouted treefrog Scinax fuscovarius (Hylidae) in the So Sebastio do Paraso farm, municipality of Boa Esperan do Sul, southeastern Brazil. This species is characterized by deirids small, simple and stylet shaped, prostom funnel-shaped with 14 teeth, conspicuous left spicule (585.7 m), distal tip slightly widened, moderately dilated, right spicule (132.9 m), boat-shaped, without dorsal barb at the distal tip, 18 pairs of caudal papillae (9 pairs precloacal and 9 pairs postcloacal), and nonfilamented eggs. This is the fourth species described for South America and the 13th for the Neotropical Region. Division of Parasitology So Paulo State University Research and Teaching Laboratory of Wild Animals So Paulo, Campus Botucatu Brazil Laboratrio de Histologia e Embriologia Animal, Instituto da Sade e Produo Animal, Universidade Federal Rural da Amaznia, Belm, Par, Brasil. . user@example.com

Biomineralization is the process in which soft organic tissues use minerals to produce shells, skeletons and teeth for various functions such as protection and physical support. The ability of the cells to control the time and place of crystal nucleation as well as crystal orientation and stiffness is far beyond the state-of-the art of human technologies. Thus, understanding the biological control of biomineralization will promote our understanding of embryo development as well as provide novel approaches for material engineering. Sea urchin larval skeletogenesis offers an excellent platform for functional analyses of both the molecular control system and mineral uptake and deposition. Here we describe the current understanding of the genetic, molecular and cellular processes that underlie sea urchin larval skeletogenesis. We portray the regulatory genes that define the specification of the skeletogenic cells and drive the various morphogenetic processes that occur in the skeletogenic lineage, including: epithelial to mesenchymal transition, cell migration, spicule cavity formation and mineral deposition into the spicule cavity. We describe recent characterizations of the size, motion and mineral concentration of the calcium-bearing vesicles in the skeletogenic cells. We review the distinct specification states within the skeletogenic lineage that drive localized skeletal growth at the tips of the spicules. Finally, we discuss the surprising similarity between the regulatory network and cellular processes that drive sea urchin skeletogenesis and those that control vertebrate vascularization. Overall, we illustrate the novel insights on the biological regulation and evolution of biomineralization, gained from studies of the sea urchin larval skeletogenesis.

Otopetrins comprise a family of proton-selective channels that are critically important for the mineralization of otoliths and statoconia in vertebrates but whose underlying cellular mechanisms remain largely unknown. Here, we demonstrate that otopetrins are critically involved in the calcification process by providing an exit route for protons liberated by the formation of CaCO(3). Using the sea urchin larva, we examined the otopetrin ortholog otop2l, which is exclusively expressed in the calcifying primary mesenchymal cells (PMCs) that generate the calcitic larval skeleton. otop2l expression is stimulated during skeletogenesis, and knockdown of otop2l impairs spicule formation. Intracellular pH measurements demonstrated Zn(2+)-sensitive H(+) fluxes in PMCs that regulate intracellular pH in a Na(+)/HCO(3)(−)-independent manner, while Otop2l knockdown reduced membrane proton permeability. Furthermore, Otop2l displays unique features, including strong activation by high extracellular pH (>8.0) and check-valve–like outwardly rectifying H(+) flux properties, making it into a cellular proton extrusion machine adapted to oceanic living conditions. Our results provide evidence that otopetrin family proton channels are a central component of the cellular pH regulatory machinery in biomineralizing cells. Their ubiquitous occurrence in calcifying systems across the animal kingdom suggest a conserved physiological function by mediating pH at the site of mineralization. This important role of otopetrin family proton channels has strong implications for our view on the cellular mechanisms of biomineralization and their response to changes in oceanic pH.

Purpose: Spicule has the ability to peel off the skin's surface layer and improve acne. Therefore, in this study, we suggest that the microdermabrasion effect of spicule cleanser improves pore keratinization of acne skin and inhibits the proliferation of skin bacteria (Propionibacterium acnes ) to improve acne lesion. Methods: There was no history of skin disease or allergy. Currently, 14 people were included in this study. Seven men and women were exposed to acne, pustules, pustules and nodules. We used the Korean Acne Grading System (KAGS) to evaluate acne and classify acne lesions every week. We conducted a questionnaire evaluation to evaluate the satisfaction and efficacy of clinical participants. The survey was analyzed using the analysis program of IBM SPSS 22.0. Results: The number of cysts, pustules and cysts decreased after 3 weeks in all 14 clinicians participating, and the acne grade improved significantly after 7 weeks. In particular, 78.5% of pores, 71.4% of acne and 95.7% of acne scars were improved. The longer the study period, the better the acne lesion was. Thus, it has been found that the microdermabrasion effect of a spicule cleanser improves the pore keratinization of acne skin and inhibits the proliferation of skin bacteria (Propionibacterium acnes ). Conclusion: As a result of KAGS analysis, the longer the treatment period, the better the acne lesion was. The spicule cleanser did not have a significant effect on gender or age. In addition, it was confirmed that it is effective for all four major diseases of acne: sebum secretion, pore keratinization, inflammation reaction, pustule and nodule.

Most sponges have biomineralized spicules. Molecular clocks indicate sponge classes diverged in the Cryogenian, but the oldest spicules are Cambrian in age. Therefore, sponges either evolved spiculogenesis long after their divergences or Precambrian spicules were not amenable to fossilization. The former hypothesis predicts independent origins of spicules among sponge classes and presence of transitional forms with weakly biomineralized spicules, but this prediction has not been tested using paleontological data. Here, we report an early Cambrian sponge that, like several other early Paleozoic sponges, had weakly biomineralized and hexactine-based siliceous spicules with large axial filaments and high organic proportions. This material, along with Ediacaran microfossils containing putative non-biomineralized axial filaments, suggests that Precambrian sponges may have had weakly biomineralized spicules or lacked them altogether, hence their poor record. This work provides a new search image for Precambrian sponge fossils, which are critical to resolving the origin of sponge spiculogenesis and biomineralization., Sponge animals likely originated in the Precambrian, but their early spicular fossils are ambiguous. Here, Tang et al. report a new Cambrian sponge taxon with weakly biomineralized spicules and suggest that the poor Precambrian record may reflect the later evolution of biomineralization.

The shape and arrangement of skeletal structures (spicules) in marine sponges are used in their taxonomic classification but shared spicule patterns often do not correspond to relationships postula...

The Pentland Hills sponge fauna (Llandovery, Telychian) consists of an unusual, aberrant assemblage, but of low diversity. A new specimen of a unique sponge,Eoghanospongia carlinslowpensisgen. et sp. nov., is described from the classic locality of R82. The mushroom-shaped, probably stalked body (peduncle attachment to body not exposed) resembles that of some living rossellids, especiallyCaulophacus. The sponge also shows prominent projecting pentactins and monaxon derivatives – a spicule type diagnostic of the Rossellidae among living taxa, albeit in a robust form not described from extant sponges, includingCaulophacusor other pedunculate lyssacinosidans. Certain attribution to the Rossellidae is not possible from the single specimen, largely because of weak preservation of the primary spicule skeleton, but no other fossil or modern sponges show any significant similarity to it. Although similarly early relatives of the Rossellidae have recently been described from elsewhere, the new sponge is even more unexpected in being from a shallow-water environment, making the absence of rossellids through the rest of the Palaeozoic much more problematic.

Maldivea Gerlach, 1962 is a possible endemic genus of the Maldivian archipelago for which only M. xarifae Gerlach, 1962 has been described so far. A new species of this genus, M. complexa n.sp., was recently found in Felidhoo atoll. It reveals a more complex structure of gubernaculum than in type species which appears to be divided into two pieces: one is a sort of long wing in the ventral part of the spicule and the other one, more complex, is characterized by several curved stripes which envelop the dorsal side of the spicule distal part. According to the present considerations, diagnoses of Paroxystomininae and Maldivea are emended.

SummaryCryptaphelenchus baujardin. sp. is described and illustrated based on two populations from Golestan province, northern Iran. The new species is characterised by female and male body length of 224 (190-261) and 215 (195-229)μm, respectively, offset cephalic region with a shallow constriction, delicate stylet 6.6 (6.0-7.0)μm long, four incisures in the lateral field, presence of a rudimentary post-uterine sac in the female gonoduct, elongate-conoid female tail ending in an acute to finely rounded terminus, male tail conical, male with seven caudal papillae and delicate spicules. The new species shows a strong resemblance toC. varicaudatusandC. iranicus, but has a sclerotised mass near the tip of the spicule and an indistinct spermatheca. Phylogenetic analyses based on both partial SSU and LSU rDNA sequences confirm its status as a new taxon.

Ektaphelenchus koreanus n. sp. is isolated from Pinus packaging wood from Korea in Ningbo customs. The new species can be characterized by having four incisures in the lateral field, the excretory pore located posterior to nerve ring, female devoid of vulval flap, and having long post-vulval intestinal sac (55–106 μm), tail with a finely rounded terminus. Six caudal papillae in male and spicule short (12.7–13.7 μm), having broad squared to rounded condylus, triangular rounded rostrum, cucullus absent. Morphologically the species is most similar with E. berbericus, E. joyceae, E. oleae, E. ibericus, and E. taiwanensis but it can be differentiated by plenty of morphometrical and morphological characters. In addition, a morphometry table of Ektaphelenchus is also presented.

Silicatein is the main protein responsible for the formation of spicules, tiny structures that constitute the silica skeleton of marine demosponges (Phylum Porifera). A unique innovation in Porifera that evolved from the cathepsin L family of proteins, it has been reported that two amino acids (S and H) are necessary to form the catalytic triad (SHN) to enable silica condensation. However, a diversity of silicatein sequence variants has since been reported with a variable pattern of presence/absence across sponge groups. Variants containing CHN or C/SQN at the active site appear more common in sponges from the Haplosclerida. Here, we report the expression levels of five silicatein variants through different developmental stages in the haplosclerid Haliclona indistincta. All five silicatein variants were expressed at low levels in the free-swimming larvae, which lack spicules and expression significantly increased at the two developmental phases in which spicules were visible. At these two phases, silicateins of CHN and C/SQN types were much more highly expressed than the SHN type indicating a possible ability of active sites with these alternative amino acids to condense silica and a more complex evolutionary story for spicule formation in marine demosponges than previously understood.

Summary Bursaphelenchus rockyi n. sp., isolated in Peking, China, from peat moss imported from Russia, is described. It is characterised by a lateral field with four lines, excretory pore located at the base of the nerve ring or slightly posterior, spicule 15.9 (15.1-17.3) μm long along the chord and with high condylus and a rounded tip, rostrum triangular or conical with bluntly pointed tip, lamina curvature becoming more pronounced at 60% of total length, six caudal papillae with P3 and P4 adjacent to each other, bursa small, starting posterior to P4, vulval lips hemispherical and protruding, and tail conical with finely rounded or mucronated terminus. The new species belongs to the fungivorus-group and is most similar to B. arthuri, B. arthuroides, B. fungivorus and B. seani, but can be distinguished from related species by morphological and sequencing results.

Dissolved silicon (DSi) is biologically processed to produce siliceous skeletons by a variety of organisms including radiolarians, silicoflagellates, choanoflagellates, plants, diatoms and some animals. In the photic ocean, diatoms are dominant consumers over competing other silicifiers. In Antarctica, where DSi is not particularly limiting, diatoms and sponges coexist in high abundances. Interestingly, diatom ingestion by sponges is a regular feeding strategy there. Although it was known that the diatom organic nutrients are readily metabolized by the sponges, what happened to the inorganic diatom silica skeleton remained unexplored. Here, we have conducted a multi-analytical approach to investigate the processing of diatom silica and whether it is reconverted into sponge silica. We have documented widespread diatom consumption by several demosponges, identifying storage vesicles for the diatom-derived silica by electron microscopy and microanalysis. Diatom-consuming sponges showed upregulation of silicatein and silicase genes, which in addition to the δ 30Si values of their silica, supports that the sponges are converting the ingested diatom silica into sponge silica without much further Si fractionation. Our multidisciplinary approach suggests that the reutilization of diatom silica by sponges is a common feature among Antarctic sponges, which should be further investigated in other latitudes and in other silicifiers.

International audience; Spicules are mineral-based biocomposites skeletal structures that are widely distributed among phylogenetically distant groups of invertebrates (Porifera, Cnidaria, Mollusca, Echinodermata). Subepidermal spicules are formed under the ectodermal epithelium and are characterized for all groups except mollusks (Aplacophora, Polyplacophora, Bivalvia), their spicules are located on the surface of the body. However, one group of mollusks (Gastropoda: Heterobranchia) have unique subepidermal spicules that have never been detected above the ectodermal epithelium and similarly to those characterized for Porifera, Cnidaria and Echinodermata. Understanding subepidermal spicule formation in mollusks could help solve the question on the origin of spicules. Spicules in nudibranchs have been described for more than 150 years, yet ontogenetic dynamics of spicules have never been studied and the full mechanism of their formation remains unknown. Herein we investigate the spicule formation in different stages of postlarval development of the nudibranch Onchidoris muricata (O.F. Müller, 1776). For the first time, ontogenetic transformations of the spicule complex are described using experiments and different morphological methods. Our studies demonstrate that spicules of O. muricata form in the subepidermal space in early developmental stages immediately after veliger settlement. A single spicule forms inside a huge vacuole within a sclerocyte and remains there throughout the entire life of the specimen. Signs of spicule or sclerocyte migration under the epithelium in postlarval development was not found. Spicules only form during larval settlement, increasing only in size as development furthers. For the first time, spicule mineralization zones were detected at the tips of the spicules as well as the presence of collagen I in the overall composition of the spicules. Thus, our findings suggest that spicules form by an ectodermal cell that emerged under the ectodermal epithelium during the earliest stages of postlarval development.

The spicules of male parasitic nematodes are key morphological features, which vary between species in shape and length and are used often for species identification. However, little is known about spicules and particularly if/how their length varies during growth. We first assessed the degree of variation in spicule length of maleHeligmosomoides bakeri21 days post infection (PI), and then in two follow-up experiments measured spicule lengths at half daily/daily intervals between days 6 and 14 PI. Mean spicule length in 21-day worms was 0.518 mm with a range of 94 μm, and variation between the two spicules of individual worms from 2 to 32 μm. Spicules were first detectable on day 6–6.5, after which their lengths increased until day 7 PI (mean = 0.61 and 0.59). This was followed by significant contraction, initially relatively quickly over the following 48 h and then more slowly over a longer period, stabilizing by days 10–14, with only minor further reduction in length. We conclude that the length of spicules varies significantly over the first few days after they have formed, and, consequently, the age of worms is an important factor for consideration when spicule lengths are measured for experimental/diagnostic or taxonomical purposes.

Background A basal spicule of the hexactinellid sponge Monorhaphis chuni may reach up to 3 m in length and 10 mm in diameter, an extreme case of large spicule size. Generally, sponge spicules are of scales from micrometers to centimeters. Due to its large size many researchers have described its structure and properties and have proposed it as a model of hexactinellid spicule development. Thorough examination of new material of this basal spicule has revealed numerous inconsistencies between our observations and earlier descriptions. In this work, we present the results of detailed examinations with transmitted light and epifluorescence microscopy, SEM, solid state NMR analysis, FTIR and X-ray analysis and staining of Monorhaphis chuni basal spicules of different sizes, collected from a number of deep sea locations, to better understand its structure and function. Results Three morphologically/structurally different silica layers i.e. plain glassy layer (PG), tuberculate layer (TL) and annular layer (AL), and an axial cylinder (AC) characterize adult spicules. Young, immature spicules display only plain glassy silica layers which dominate the spicule volume. All three layers i.e. PG, TL and AL can substitute for each other along the surface of the spicule, but equally they are superimposed in older parts of the spicules, with AL being the most external and occurring only in the lower part of the spicules and TL being intermediate between AL and PG. The TL, which is composed of several thinner layers, is formed by a progressive folding of its surface but its microstructure is the same as in the PG layer (glassy silica). The AL differs significantly from the PG and TL in being granular and porous in structure. The TL was found to display positive structures (tubercles), not depressions, as earlier suggested. The apparent perforated and non-perforated bands of the AL are an optical artefact. The new layer type that we called the Ripple Mark Layer (RML) was noted, as well as narrow spikes on the AL ridges, both structures not reported earlier. The interface of the TL and AL, where tubercles fit into depressions of the lower surface of the AL, represent tenon and mortise or dovetail joints, making the spicules more stiff/strong and thus less prone to breaking in the lower part. Early stages of the spicule growth are bidirectional, later growth is unidirectional toward the spicule apex. Growth in thickness proceeds by adding new layers. The spicules are composed of well condensed silica, but the outermost AL is characterized by slightly more condensed silica with less water than the rest. Organics permeating the silica are homogeneous and proteinaceous. The external organic net (most probably collagen) enveloping the basal spicule is a structural element that bounds the sponge body together with the spicule, rather than controlling tubercle formation. Growth of various layers may proceed simultaneously in different locations along the spicule and it is sclerosyncytium that controls formation of silica layers. The growth in spicule length is controlled by extension of the top of the axial filament that is not enclosed by silica and is not involved in further silica deposition. No structures that can be related to sclerocytes (as known in Demospongiae) in Monorhaphis were discovered during this study. Conclusions Our studies resulted in a new insight into the structure and growth of the basal Monorhaphis spicules that contradicts earlier results, and permitted us to propose a new model of this spicule’s formation. Due to its unique structure, associated with its function, the basal spicule of Monorhaphis chuni cannot serve as a general model of growth for all hexactinellid spicules.