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Eulimidae is a prominent group within the class Gastropoda, comprising 1087 species that have developed specialised symbiotic relationships with all extant echinoderm classes. At least 47 species of eulimids can be found in the waters of Vietnam. Representatives of the genus Pulicicochlea, the species Vitreobalcis tripneusticola, and four new undescribed species were observed for the first time. In this study, we update the existing checklists of Vietnamese eulimids, emphasising the use of molecular barcoding to determine the phylogenetic relationships among the collected species. The classical taxonomy of molluscs relies heavily on the morphology of the shell and radula. The family Eulimidae presents challenges as in many species these features are poorly developed, and molecular phylogenetic methods have proven to be more informative for the taxonomy and systematics of this family. To understand the evolutionary pathways in Eulimidae, we constructed a COI-based phylogenetic tree, which included original sequences primarily from Vietnam and all available sequences for Eulimidae from GenBank. The newly obtained genetic information is crucial for enhancing our understanding of this family of gastropod mollusсs, as well as for any future revisions that may be necessary. [ABSTRACT FROM AUTHOR]

The Pliensbachian (Lower Jurassic) age-based Lower Marly Limestone Formation of the Moulay Idriss Zerhoun area (Morocco) and the Ain Ouarka Formation of the Ksour Mountains (Algeria) have yielded rare crinoids. Although crinoids have previously been described from the Jurassic of Algeria, their Pliensbachian occurrence is being reported here for the first time. On the other hand, one isocrinid taxa [Terocrinus subsulcatus (Münster in Goldfuss)] was also recorded from the Pliensbachian strata of Morocco. Additionally, now, from both Morocco and Algeria, Seirocrinus subangularis (Miller), belonging to the family Pentacrinitidae, is documented. This is a cosmopolitan and pseudoplaktonic crinoid species that is well-known from Asia, Europe, and North America. The taxonomic evaluation of the genus Seirocrinus is provided. The present records from Algeria and Morocco are the first finds of Seirocrinus from the African continent. Ticinocrinus moroccoensis sp. nov. represented by a cup of a rare cyrtocrinid (Cyrtocrinida) is associated with S. subangularis from Morocco. Globally, this is the second record of the genus; the first Ticinocrinus being described from the Pliensbachian of Switzerland. Thus, the present records from Morocco and Algeria are also the oldest cyrtocrinids from the southern margin of the Tethys. [ABSTRACT FROM AUTHOR]

A representative complex of the Turonian-Santonian carbonate-producing invertebrates has been revealed. It comprised benthic foraminifers, diverse echinoderms, brachiopods, calcareous and siliceous sponges.

Abstract The predation-driven Mesozoic marine revolution (MMR) is believed to have induced a dramatic change in the bathymetric distribution of many shallow marine invertebrates since the late Mesozoic. For instance, stalked crinoids – isocrinids (Isocrinida) have undergone a striking decline in shallow-sea environments and today they are restricted to deep-sea settings (below 100 m depth). However, the timing and synchronicity of this shift are a matter of debate. A delayed onset of MMR and/or shifts to a retrograde, low-predation community structure during the Paleogene in the Southern Ocean were invoked. In particular, recent data from the Southern Hemisphere suggest that the environmental restriction of isocrinids to the deep-sea settings may have occurred at the end of the Eocene around Antarctica and Australia, and later in the early Miocene in New Zealand. Here, we report the anomalous occurrence of the isocrinids in shallow nearshore marine facies from the middle Miocene of Poland (Northern Hemisphere, Central Paratethys). Thus, globally, this is the youngest record of shallow-sea stalked crinoids. This finding suggests that some relict stalked crinoids may have been able to live in the shallow-water environments by the middle Miocene, and further confirms that the depth restriction of isocrinids to offshore environments was not synchronous on a global scale.

Abstract Studies of morphology and developmental patterning in adult stages of many invertebrates are hindered by opaque structures, such as shells, skeletal elements, and pigment granules that block or refract light and necessitate sectioning for observation of internal features. An inherent challenge in studies relying on surgical approaches is that cutting tissue is semi-destructive, and delicate structures, such as axonal processes within neural networks, are computationally challenging to reconstruct once disrupted. To address this problem, we developed See-Star, a hydrogel-based tissue clearing protocol to render the bodies of opaque and calcified invertebrates optically transparent while preserving their anatomy in an unperturbed state, facilitating molecular labeling and observation of intact organ systems. The resulting protocol can clear large (> 1 cm3) specimens to enable deep-tissue imaging, and is compatible with molecular techniques, such as immunohistochemistry and in situ hybridization to visualize protein and mRNA localization. To test the utility of this method, we performed a whole-mount imaging study of intact nervous systems in juvenile echinoderms and molluscs and demonstrate that See-Star allows for comparative studies to be extended far into development, facilitating insights into the anatomy of juveniles and adults that are usually not amenable to whole-mount imaging.

In many countries, such as Norway, there are vast quantities of sea urchins that have formed barrens over large areas of the coastline. Research has shown that removal of sufficient quantities of sea urchins from these barrens can lead to them reverting to a macroalgae forest. Identifying the chemical composition of sea urchins for various uses, such as agricultural fertiliser, would incentivise this sea urchin removal. This study investigates the composition of sea urchins and whether the composition varies when sea urchin collection sites vary both geographically and temporally. Sea urchins were collected from three sites within 10 km of each other in northern Norway at three times through the year. The sea urchins were dried, crushed, powdered, and analysed for nutrient content. An elemental analysis from the sea urchin samples showed high calcium and relatively high magnesium levels; smaller relative quantities of nitrogen, phosphorous, and potassium were also found. Micronutrients such as iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu) were found. More importantly, both primary, macro-, and micronutrients showed high variability when collected from different sites and at different times of the year. This will be a critical consideration when investigating the use of this product as a plant fertiliser or for any other use. [ABSTRACT FROM AUTHOR]

The predation-driven Mesozoic marine revolution (MMR) is believed to have induced a dramatic change in the bathymetric distribution of many shallow marine invertebrates since the late Mesozoic. For instance, stalked crinoids – isocrinids (Isocrinida) have undergone a striking decline in shallow-sea environments and today they are restricted to deep-sea settings (below 100 m depth). However, the timing and synchronicity of this shift are a matter of debate. A delayed onset of MMR and/or shifts to a retrograde, low-predation community structure during the Paleogene in the Southern Ocean were invoked. In particular, recent data from the Southern Hemisphere suggest that the environmental restriction of isocrinids to the deep-sea settings may have occurred at the end of the Eocene around Antarctica and Australia, and later in the early Miocene in New Zealand. Here, we report the anomalous occurrence of the isocrinids in shallow nearshore marine facies from the middle Miocene of Poland (Northern Hemisphere, Central Paratethys). Thus, globally, this is the youngest record of shallow-sea stalked crinoids. This finding suggests that some relict stalked crinoids may have been able to live in the shallow-water environments by the middle Miocene, and further confirms that the depth restriction of isocrinids to offshore environments was not synchronous on a global scale. [ABSTRACT FROM AUTHOR]

Crinoids of the Order Comatulida are renowned for harboring a remarkable diversity of symbiotic organisms within echinoderms, including polychaetes, myzostomids, gastropods, crustaceans, brittle stars, or fish. Crinoids provide essential services to their symbionts, such as shelter, access to food resources, mating areas, nesting grounds, and nurseries. Symbionts within crinoids developed a variety of strategies, including foraging in the arm ambulacral grooves, preying upon other symbionts, living within galls, or accessing suspended food particles from the water column. In this work, we focused on the Great Reef of Toliara, where we collected specimens from seven crinoid species. Among the 84 crinoids examined, a total of 285 symbiotic organisms were retrieved. These symbionts were either moving freely on their host or found within cysts. Stable isotope analyses of carbon and nitrogen for both hosts and symbionts have shown that (a) all crinoids shared a common trophic niche; (b) a community-based approach indicated that crinoids initiated trophic networks primarily based on suspended particulate organic matter; (c) non-specific symbionts exhibited consistent dietary preferences regardless of their host; (d) myzostomids inhabiting cysts were found to feed on their host tissues; and (e) free-moving symbionts displayed divergent trophic niches linked to their predatory, kleptoparasitic, or filter-feeding behaviors. This research underscores the role of crinoids, particularly comatulid species, as key components of tropical ecosystems in the Western Indian Ocean, inhabited by a hidden biodiversity with complex trophic networks. Their intricate morphology accommodates a range of feeding strategies, supporting a diverse associated fauna. [ABSTRACT FROM AUTHOR]

Studies of morphology and developmental patterning in adult stages of many invertebrates are hindered by opaque structures, such as shells, skeletal elements, and pigment granules that block or refract light and necessitate sectioning for observation of internal features. An inherent challenge in studies relying on surgical approaches is that cutting tissue is semi-destructive, and delicate structures, such as axonal processes within neural networks, are computationally challenging to reconstruct once disrupted. To address this problem, we developed See-Star, a hydrogel-based tissue clearing protocol to render the bodies of opaque and calcified invertebrates optically transparent while preserving their anatomy in an unperturbed state, facilitating molecular labeling and observation of intact organ systems. The resulting protocol can clear large (> 1 cm3) specimens to enable deep-tissue imaging, and is compatible with molecular techniques, such as immunohistochemistry and in situ hybridization to visualize protein and mRNA localization. To test the utility of this method, we performed a whole-mount imaging study of intact nervous systems in juvenile echinoderms and molluscs and demonstrate that See-Star allows for comparative studies to be extended far into development, facilitating insights into the anatomy of juveniles and adults that are usually not amenable to whole-mount imaging. [ABSTRACT FROM AUTHOR]

To explore animal diversity, new experimentally tractable organisms must be established. Echinoderms include five groups of marine animals that have been used as developmental models for over a century thanks to their low costs, high fecundity, optically clear larvae and genetic tractability. An additional advantage of echinoderms is that their larval forms display diverse morphologies. This rich diversity enables comparative studies to investigate the evolutionary relationships among cell types, tissues, and organs. However, reproducible protocols to obtain gametes, detailed information on embryogenesis, and genomic tools have been optimized only for selected species of sea urchins and sea stars. To address this gap, we established the abundant Mediterranean sea cucumber Holothuria tubulosa as a new experimental system. Here we describe a method to reliably obtain gametes and make embryonic cultures multiple times from the same animal and characterize unique larval tissues combining immunohistochemistry and high-resolution microscopy. This work represents a step forward in our understanding of holothurian development and establishes H. tubulosa as an emerging experimental system for evo-devo and other biological disciplines. [ABSTRACT FROM AUTHOR]

In this catalogue, 80 species of ophiuroids collected by the IN2021_V04 and IN2022_V08 expeditions to the Australian Christmas Island and Cocos (Keeling) Islands Territories are described and illustrated. [ABSTRACT FROM AUTHOR]

• Sahune (Oxfordian, Late Jurassic) in south-eastern France Basin is newly described. • Carbonate bodies enclosed within Terres Noires Formation formed at cold seeps. • Associated fauna indicate seepage at bathyal depth ca. 1.500 m. • Several seep ostracod families have evolved at seeps since the Oxfordian. • Colonization of bathyal environments occurred earlier than thought. Hydrocarbon seeps represent some of the most extreme marine habitats but are also home to rich communities developed around chemosynthesis rather than photosynthesis. Here we describe the outcrop of Sahune (Drôme department, south-eastern France), that illustrates a new seeping site during the Late Jurassic (middle Oxfordian), as formally demonstrated by geochemical proxies. We report the associated fauna composed of foraminifers, radiolarians, crinoids, echinoids and ostracods that all point to seepage at bathyal depth. The foraminifer assemblage and the occurrence of the irregular echinoid Tithonia oxfordiana together point to a middle Oxfordian age. We provide an in-depth analysis of the ostracod community, which is the oldest so far reported in such environments. The new species Procytherura praecoquum may be cognate to the seepage site and could illustrate the oldest known example of pore clusters, sometimes proposed as representing ectosymbiosis. The Sahune assemblage demonstrates that cold seep ostracod communities were already a mixture of taxa from platform and deep-sea oligotrophic environments. The post-Jurassic diversification of ostracods at cold seeps was related to colonization events and diversification of families that have been inhabitants of such ecosystems at least since the Oxfordian. The Sahune record changes our current conception of the deep-sea colonization by the ostracods Tethysia and Procytherura that occurred earlier than traditionally considered. [ABSTRACT FROM AUTHOR]

The commercial importance of benthic macroinvertebrates like echinoderms and molluscs has led to the overexploitation of wild stocks in many areas around the Philippines. Despite their ecological and economic importance, studies on the status of wild populations of commercial macroinvertebrates in unexploited habitats such as marine protected areas (MPAs) are very scarce. The diversity and abundance of commercially valuable echinoderms and molluscs in the seagrass and reefs of Danjugan Island Marine Reserve were assessed. Shallow areas (1-3 m depth) around the island were surveyed both during the day and after dusk using belt transects. A total of 226 individuals belonging to 21 different taxa were recorded during the surveys, of which 71% were molluscs and 29% were echinoderms. In the seagrass habitat, Cypraeidae, Toxopneustidae, and Conidae were the dominant families, while molluscs from the Cardiidae family comprised more than half of the total assemblage in the reef flat. The most diverse commercial macroinvertebrate group was Holothuriidae with five different species. The densities of the families were higher during dusk than during the day in both habitats, except for Cardiidae in the seagrass. The highest values of species richness and H' index were observed during dusk surveys in the reef habitat (H'= 1.57), while the lowest was observed in seagrass areas during morning surveys (H'= 1.37). This is the first study that assessed commercially valuable macroinvertebrates during day and night in two connected habitats within a protected area. The differences in diversity and abundance in each habitat depending on the time of day highlight the importance of considering these factors when evaluating macroinvertebrate populations in unexploited areas. [ABSTRACT FROM AUTHOR]

A growing number of recent studies have demonstrated that introgression is common across the tree of life. However, we still have a limited understanding of the fate and fitness consequence of introgressed variation at the whole-genome scale across diverse taxonomic groups. Here, we implemented a phylogenetic hidden Markov model to identify and characterize introgressed genomic regions in a pair of well-diverged, nonsister sea urchin species: Strongylocentrotus pallidus and Strongylocentrotus droebachiensis. Despite the old age of introgression, a sizable fraction of the genome (1% to 5%) exhibited introgressed ancestry, including numerous genes showing signals of historical positive selection that may represent cases of adaptive introgression. One striking result was the overrepresentation of hyalin genes in the identified introgressed regions despite observing considerable overall evidence of selection against introgression. There was a negative correlation between introgression and chromosome gene density, and two chromosomes were observed with considerably reduced introgression. Relative to the nonintrogressed genome-wide background, introgressed regions had significantly reduced nucleotide divergence (d XY) and overlapped fewer protein-coding genes, coding bases, and genes with a history of positive selection. Additionally, genes residing within introgressed regions showed slower rates of evolution (d N, d S, d N/ d S) than random samples of genes without introgressed ancestry. Overall, our findings are consistent with widespread selection against introgressed ancestry across the genome and suggest that slowly evolving, low-divergence genomic regions are more likely to move between species and avoid negative selection following hybridization and introgression. [ABSTRACT FROM AUTHOR]

In May 2023, oceanic and atmospheric anomalies indicated El Niño conditions in the eastern Pacific, followed by coral bleaching in coral communities and reefs of Huatulco. We conducted surveys and sampled coral reef communities from late June to mid–August of 2023 to evaluate the intensity and extent of the changes associated with the warming event. From January of 2023, Huatulco experienced positive sea surface temperature (SST) anomalies; however, beginning in June, the high-temperature anomalies became extreme (>31 °C; ~2 °C above historical records). These high temperatures resulted in extensive coral bleaching in middle–late June and mortality from middle–late July (>50–93%). In addition, the area experienced significant reductions in echinoderm abundance and fish biomass. In 2023, severe bleaching affected coral systems in the Central Mexican Pacific, Gulf of Mexico, and Mexican Caribbean, making this the most devastating marine heatwave event, simultaneously impacting coral reefs across Mexico's Pacific and Atlantic coasts. [ABSTRACT FROM AUTHOR]

Metabarcoding is revolutionising the analysis of biodiversity in marine ecosystems, especially as it provides a means of detecting and identifying cryptic life stages in field samples. The planktonic larval stage of many species underpins the abundance and distribution of adult populations but is challenging to characterise given the small size of larvae and diffuse distributions in pelagic waters. Yet, planktonic larval dynamics are key to understanding phenomena observed in adult populations, such as the boom-and-bust dynamics exhibited by some echinoderms. Rapid changes in echinoderm population density can have significant effects on local benthic ecosystems. For example, outbreaks of the crown-of-thorns sea star (CoTS) on the Great Barrier Reef (GBR) have led to considerable declines in coral cover. Here, we used a DNA metabarcoding approach to investigate the spatio-temporal distribution and diversity of echinoderm larvae on the GBR, including CoTS. Generalised linear mixed models revealed that echinoderm larval richness, was significantly correlated with temporal variables (i.e. season and year) which is consistent with expected fluctuations in larval output based on adult spawning periodicity. However, neither site-specific differences in echinoderm larval richness, nor correlations between larval composition and environmental, temporal, or spatial variables were found. This study validates the utility of metabarcoding approaches for detecting and characterising echinoderm larvae, including CoTS, which could prove useful to future monitoring efforts. Our findings suggest that metabarcoding can be used to better understand the life history of planktonic larvae, and analyses combining environmental (e.g., temperature, nutrients) and oceanographic (e.g., currents) data could deliver valuable information on the factors influencing their spatio-temporal distributions. [ABSTRACT FROM AUTHOR]

In May 2023, oceanic and atmospheric anomalies indicated El Niño conditions in the eastern Pacific, followed by coral bleaching in coral communities and reefs of Huatulco. We conducted surveys and sampled coral reef communities from late June to mid–August of 2023 to evaluate the intensity and extent of the changes associated with the warming event. From January of 2023, Huatulco experienced positive sea surface temperature (SST) anomalies; however, beginning in June, the high-temperature anomalies became extreme (>31 °C; ~2 °C above historical records). These high temperatures resulted in extensive coral bleaching in middle–late June and mortality from middle–late July (>50–93%). In addition, the area experienced significant reductions in echinoderm abundance and fish biomass. In 2023, severe bleaching affected coral systems in the Central Mexican Pacific, Gulf of Mexico, and Mexican Caribbean, making this the most devastating marine heatwave event, simultaneously impacting coral reefs across Mexico’s Pacific and Atlantic coasts.

Many animals have pigments when they themselves cannot see colour. Perhaps those pigments enable the animal to avoid predators, or to attract mates. Maybe even those pigmented surfaces are hosts for microbes, even when the microbes do not see colour. Do some pigments then serve as a chemical signal for a good or bad microbial substrate? Maybe pigments attract or repel various microbe types? Echinoderms serve as an important model to test the mechanisms of pigment-based microbial interactions. Echinoderms are marine benthic organisms, ranging from intertidal habitats to depths of thousands of metres and are exposed to large varieties of microbes. They are also highly pigmented, with a diverse variety of colours between and even within species. Here we focus on one type of pigment (naphthoquinones) made by polyketide synthase, modified by flavin-dependent monoxygenases, and on one type of function, microbial interaction. Recent successes in targeted gene inactivation by CRISPR/Cas9 in sea urchins supports the contention that colour is more than it seems. Here we dissect the players, and their interactions to better understand how such host factors influence a microbial colonization. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'. [ABSTRACT FROM AUTHOR]

In this catalogue, the 17 species of echinoids collected by the IN2021_V04 and IN2022_V08 expeditions to the Australian Christmas Island and Cocos (Keeling) Islands Territories are described and illustrated. Ashley Miskelly. 2024. Catalogue of the Echinoidea (sea urchins, phylum Echinodermata) collected by the IN2021_V04 and IN2022_V08 expeditions to the Australian Christmas Island and Cocos (Keeling) Islands Territories. [ABSTRACT FROM AUTHOR]

Echinoderms are a major group (phylum) of invertebrate animals with a rich fossil record stretching back to the Cambrian period, approximately 518 million years ago. While all modern species are characterized by pentaradial (i.e., fivefold) symmetry, Cambrian echinoderms also include taxa with different types of symmetry (e.g., bilateral symmetry). These distinct forms were present from very early in the phylum's history, demonstrating that the initial diversification of echinoderm body plans was extremely rapid. The phylogenetic relationships of Cambrian echinoderms have long been debated, hindering efforts to reconstruct the evolution of the phylum, but recent analyses have consistently recovered bilaterally symmetrical forms as the earliest-diverging echinoderms. This reveals the sequence of character acquisition in echinoderm evolution, indicating that radial symmetry is a derived character of the group, which evolved after the acquisition of a mineralized skeleton. Cambrian echinoderms were adapted to diverse modes of life, with ecology an important factor shaping their early evolution. However, the reasons why echinoderms evolved their unique pentaradial body plan remain unclear. The Cambrian fossil record provides valuable insights into the origin and early evolution of echinoderms over half a billion years ago. Cambrian echinoderms were morphologically diverse, with several extinct groups exhibiting character combinations that distinguish them from living species. Phylogenetic analyses of bilateral, asymmetrical, triradial, and pentaradial fossils have allowed us to decipher the assembly of the modern echinoderm body plan. Echinoderms became ecologically diverse early in their history, with varied modes of feeding, locomotion, and attachment. [ABSTRACT FROM AUTHOR]

In this catalogue, 30 species from 25 genera and 11 families, of Asteroidea collected by the IN2021_;V04 and IN2022_;V08 expeditions to the Australian Christmas Island and Cocos (Keeling) Islands Territories are described and illustrated. [ABSTRACT FROM AUTHOR]

Three new bibenzochromenones named phanogracilins A–C (1–3) were isolated from the crinoid Phanogenia gracilis. The structure of 1 was established using X-ray crystallography as 5,5′,6,6′,8,8′-hexahydroxy-2,2′-dipropyl-4H,4′H-[7,9′-bibenzo[g]chromene]-4,4′-dione. This allowed us to assign reliably 2D NMR signals for compound 1 and subsequently for its isomer 2 that differed in the connecting position of two benzochromenone moieties (7,10′ instead of 7,9′), and compound for 3 that differed in the length of the aliphatic chain of one of the fragments. Compound 4 was derived from 1 in alkaline conditions, and its structure was elucidated as 5,5′,6′,8,8′-pentahydroxy-2,2′-dipropyl-4H,4′H-[7,9′-bibenzo[g]chromene]-4,4′,6,9-tetraone. Even though compounds 1–4 did not contain stereo centers, they possessed notable optical activity due to sterical hindrances, which limited the internal rotation of two benzochromenone fragments around C(7)–C(9′/10′) bonds. Isolated bibenzochromenones 1–4 were tested for their antiradical, neuroprotective and antimicrobial activities. Compounds 1, 3 and 4 demonstrated significant antiradical properties towards ABTS radicals higher than the positive control trolox. Compounds 1 and 4 exhibited moderate neuroprotective activity, increasing the viability of rotenone-treated Neuro-2a cells at a concentration of 1 µM by 9.8% and 11.8%, respectively. Compounds 1 and 3 at concentrations from 25 to 100 μM dose-dependently inhibited the growth of Gram-positive bacteria S. aureus and yeast-like fungi C. albicans, and they also prevented the formation of their biofilms. Compounds 2 and 4 exhibited low antimicrobial activity. [ABSTRACT FROM AUTHOR]

Introduction: Short-term gametes storage is an inexpensive and simple technique that allows the use of the same batch of eggs or sperm at different times, maximizing the application of research protocols and the use of gametes in production. Arbacia dufresnii is a sea urchin species with proven aquaculture potential and already used in the nutraceutical industry. Aging of its gametes is unknown and is a needed information to scale up the production. Objective: Determine the effect of male and female gamete aging on the fertilization success of Arbacia dufresnii. This will allow optimizing the use of gametes after collection decoupling spawning from fertilization. Methods: A. dufresnii individuals were induced to spawn and gametes were kept at 12 ± 1 °C throughout each bioassay. Sperm was separated into two treatments: activated sperm in seawater (AS), and dry sperm (DS). Two bioassays were made: Bioassay 1 evaluated the effect of time on fertility by performing fertilization tests at 0 h, 24 h, 48 h, 72 h, and 96 h after spawning. Bioassay 2 evaluated the contribution of each type of aged gamete on fertility, combining aged gametes (96 h) with fresh gametes (0 h). Results: Bioassay 1: the fertilization success obtained by combining eggs (E) with AS or DS presented important differences. While the fertilization success remained acceptable (greater than 50 %) for up to 72 h using ExDS, it only remained acceptable for up to 48 h using ExAS. Bioassay 2: acceptable fertilization success was found by combining aged E (96 h) with fresh sperm, or aged DS (96 h) with fresh E, but not using aged AS with fresh E. Conclusions: The findings of this work show that fertilization success in A. dufresnii gametes remains relatively unchanged for up to 48 h after spawning when combining ExAS, and for up to 72 h when combining ExDS. However, when combining aged E or aged DS with a fresh gamete, post-collection fertilization can be extended up to 96 h. In this work, the first steps have been taken to understand the conservation time of A. dufresnii gametes with minimum intervention. [ABSTRACT FROM AUTHOR]

Introduction: Echinoderms, an integral component of marine ecosystems worldwide, have captivated scientific interest for centuries. Despite this longstanding attention, comprehending key facets such as trophic relationships, diet composition, and host-microbiota relationships still represents a challenge using traditional techniques. Recent years, however, have witnessed a transformative shift, thanks to the emergence of advanced molecular techniques, offering new approaches to strengthen ecological studies in echinoderms. Objective: Explore how recent advancements in molecular tools have impacted ecological research on echinoderms. Specifically, we aim to investigate the potential of these tools to shed light on trophic interactions, diet composition, and the characterization of gut microbial communities in these organisms. Methods: Available literature was used to clarify how novel molecular techniques can improve ecological studies. The focus is diet, trophic relationships, and gut microbiota. Results: Traditionally, studies of stomach contents using compound microscopy have provided an idea of ingested material; nevertheless, sometimes a simple magnified visualization of dietary content does not allow exhaustive identification of the entire food spectrum, as it is limited due to the rapid digestion and maceration of food items within the echinoderm's digestive tract. The use of DNA-metabarcoding, targeting specific DNA regions, such as the mitochondrial COI gene, has allowed us to enhance the accuracy and precision of diet characterization by enabling the identification of prey items down to the species or even genetic variant level, providing valuable insights into specific dietary preferences. Another approach is the use of stable isotopes, particularly carbon and nitrogen, which provide a powerful tool to trace the origin and flow of nutrients through food webs. By analyzing the isotopic signatures in muscular tissues and food items, we can discern the sources of their primary food items and gain insights into their trophic position within the ecosystem. Lastly, a third new technique used to elucidate the characterization of the prokaryotic community is 16S rRNA sequencing. This method allows us to explore the composition and dynamics of the digestive tract microbial communities. Conclusions: This is a promising era for ecological research on echinoderms, where advances of molecular tools have enabled an unprecedented level of detail, resolving longstanding challenges in comprehending their trophic interactions, diet composition, and host-microbiota relationships, and opening new avenues of investigation in ecological studies. [ABSTRACT FROM AUTHOR]

Middle–Upper Carboniferous (Pennsylvanian) crinoids with aberrant arm branches from the Moscow region are studied. It is shown that aberrations in the arm branches can be the result of mechanical damage during incorrect (augmentative) regeneration, as previously assumed, or the result of initial phenotype disorders. The latter cases show the evolutionary potential of the group. Consolidation of such aberrations in the phylogenies of certain groups of crinoids led to speciation and formation of new taxa. [ABSTRACT FROM AUTHOR]

The lithological, paleontological and biostratigraphic characteristics of the Turonian–Coniacian deposits of the Lower Bannovka section, the stratotype of the Bannovka Formation (Volga region, Turonian) are presented. Magnetostratigraphic characteristics of thе sediments have been supplemented and elaborated. Petromagnetic data contribute to more refined stratigraphy of the section and facilitate the revealing of depositional rhythmicity. Paleomagnetic data combined with benthic foraminifera data enable the most detailed correlation of the Turonian–Coniacian deposits in the Volga region. Results of a comprehensive study of this stratigraphic unit within the southeastern arch of the Ulyanovsk-Saratov trough revealed patterns in the distribution of the Gubkino Horizon, determined by regional tectonics and processes preceding deposition in the Coniacian and Santonian. [ABSTRACT FROM AUTHOR]

Traces of burst oxygen bubbles in a cyanobacterial mat on the surface of carbonate layers of the Middle Cambrian (Amgian, Stage 5 of Series 3) on the left bank of the Lena River (Yakutia) are described and their origin is discussed. They appear to be similar to some Vendian (Ediacaran) fossils usually described as remains of metazoans (e.g., edrioasteroids). [ABSTRACT FROM AUTHOR]

Dorometra Clark, 1917 (Comatulida: Antedonidae) is an Indo-Pacific genus of small-sized cryptic feather stars currently comprising nine species. The monophyly of this crinoid genus has been widely questioned, although only few studies have investigated the phylogeny of Antedonidae in depth. In this study we used an integrated approach combining molecular phylogenetic, morphology, and multivariate analyses to clarify the taxonomic placement of the genus Dorometra within family Antedonidae. Eight of the nine known species of the genus collected from Australia to the Sea of Japan were included in analyses. Phylogenetic analyses using sequences from two mitochondrial (COI, 16S) and one nuclear (28S) genes demonstrate that Dorometra is polyphyletic, and its species are divided into three main clades, which are spread within other Antedonidae. As a result, we herein describe Nesometra gen. nov. Four different species delimitation methods on single and multi-locus alignments also showed higher diversity than previously thought. In particular, our results highlighted the presence of cryptic diversity within the species Dorometra nana (Hartlaub, 1890) in geographically close localities within southern Japan. By multivariate analysis of morphological matrix, we confirmed the homoplasy and plasticity of the taxonomic characters used in the description of Dorometra species, providing a path forward for the general taxonomic revision of this genus and of Antedonidae and related families. [ABSTRACT FROM AUTHOR]

Background: Echinoderms have long been utilized as experimental materials to study the genetic control of developmental processes and their evolution. Among echinoderms, the molecular study of starfish embryos has received considerable attention across research topics such as gene regulatory network evolution and larval regeneration. Recently, experimental techniques to manipulate gene functions have been gradually established in starfish as the feasibility of genome editing methods was reported. However, it is still unclear when these techniques cause genome cleavage during the development of starfish, which is critical to understand the timeframe and applicability of the experiment during early development of starfish. Results: We herein reported that gene functions can be analyzed by the genome editing method TALEN in early embryos, such as the blastula of the starfish Patiria pectinifera. We injected the mRNA of TALEN targeting rar, which was previously constructed, into eggs of P. pectinifera and examined the efficiency of genome cleavage through developmental stages from 6 to 48 hours post fertilization. Conclusion: The results will be key knowledge not only when designing TALEN‐based experiments but also when assessing the results. Key Findings: Molecular study of starfish embryos has received considerable attention in recent years.It is important to establish a robust assay of the genome editing with not only CRISPR/Cas9 but TALEN in starfish.However, it is still unclear when TALEN causes genome cleavage during the development of starfish.The results will be key knowledge not only when designing TALEN‐based experiments but also when assessing the results. [ABSTRACT FROM AUTHOR]

Context: In Tasmania, Australia, the government's response to range-extending, barren-forming longspined sea urchin (Centrostephanus rodgersii) includes rebuilding of southern rock lobster (Jasus edwardsii) stocks to increase predation. But lobster preference for native species and continued barren expansion challenges the control efficacy. Aims: To determine the impact of lobster predation on C. rodgersii in different habitats. Methods: Multi-method dietary analysis consisting of stomach contents, faecal DNA and stable isotopes was performed on 64 lobsters from four habitats varying in barren extent and density of urchins and lobsters. Key results: C. rodgersii contributed to lobster diet in all barren habitats and was found in lobsters of every size class. Stable isotope and DNA analyses showed that C. rodgersii was more common in lobster diet than were targeted native species at incipient barren sites. Surprisingly, in extensive barrens C. rodgersii is less prominent in lobster diet. Conclusions: Combined with site-specific urchin population data, our findings indicated that lobster predation may be less effective at sites where most C. rodgersii individuals have reached a size refuge than at sites dominated by small urchins. Implications: Lobster predation may provide a useful control for smaller C. rodgersii , but top–down predatory control may be constrained at sites dominated by urchins that exceed the size suitable for lobster predation. Using a diverse set of methods, we investigated lobster diet in Tasmania to see whether lobsters prey on, and, consequently, contribute to the control of a destructive, range-extending sea urchin. We found that lobsters do consume the urchins, but to a lesser extent in the habitat where suitably sized urchins are scarce. These findings highlight the complexity of using native predators for pest control. [ABSTRACT FROM AUTHOR]

To explore animal diversity, new experimentally tractable organisms must be established. Echinoderms include five groups of marine animals that have been used as developmental models for over a century thanks to their low costs, high fecundity, optically clear larvae and genetic tractability. An additional advantage of echinoderms is that their larval forms display diverse morphologies. This rich diversity enables comparative studies to investigate the evolutionary relationships among cell types, tissues, and organs. However, reproducible protocols to obtain gametes, detailed information on embryogenesis, and genomic tools have been optimized only for selected species of sea urchins and sea stars. To address this gap, we established the abundant Mediterranean sea cucumber Holothuria tubulosa as a new experimental system. Here we describe a method to reliably obtain gametes and make embryonic cultures multiple times from the same animal and characterize unique larval tissues combining immunohistochemistry and high-resolution microscopy. This work represents a step forward in our understanding of holothurian development and establishes H. tubulosa as an emerging experimental system for evo-devo and other biological disciplines.

The western Iberian Chain of NE Spain represents a lateral prolongation of the West Asturian-Leonese Zone. As other proximal sectors fringing NW Gondwana, the chain comprises a con­formable and continuous FurongianâTremadocian transition, comprising a thick (3600â4500 m) Lower Ordovician sedimentary succession, exclusively composed of siliciclastic strata and deposited in mid-latitude (temperate) waters. Although the shelly fossil record is not abundant, some key trilobites and brachiopods allow the identification of distinct biogeographic links with the Argentinian margin of West Gondwana, Oaxaca (Mexico), and the neighbouring Montagne Noire (France), with which a common biostratigraphic biozonation can be enviaged. Two phosphoritic interbeds rich in linguliformean brachiopods punctuate the Valconchán and Borrachón formations, and represent event beds related to condensation processes and sedimentation of explosive ignimbritic tuffs, respectively.

Simple Summary: Invertebrates (animals without backbones) make up over 95% of the earth's species yet compared with vertebrates (animals with backbones like fishes, amphibians, reptiles, birds, and mammals) our understanding of and efforts relating to the topic of welfare is relatively minimal. We have selected seven of the most economically important and widely recognized invertebrate taxa to focus the topic of animal welfare on. In these pages the reader will learn about coelenterates (jellyfishes, anemones, and corals), mollusks (snails, slugs, squid, and octopi), crustaceans (lobsters, crabs, and shrimp), echinoderms (sea stars, sea urchins, and sea cucumbers), chelicerates (spiders, scorpions, and horseshoe crabs), myriapods (centipedes and millipedes), and insects (butterflies, honeybees, and fruit flies). In addition to discussing the welfare of these species, other topics, including anatomy, physiology, husbandry, natural history, and environmental diseases, are reviewed. Invertebrates are a diverse group of animals that make up the majority of the animal kingdom and encompass a wide array of species with varying adaptations and characteristics. Invertebrates are found in nearly all of the world's habitats, including aquatic, marine, and terrestrial environments. There are many misconceptions about invertebrate sentience, welfare requirements, the need for environmental enrichment, and overall care and husbandry for this amazing group of animals. This review addresses these topics and more for a select group of invertebrates with biomedical, economical, display, and human companionship importance. [ABSTRACT FROM AUTHOR]

Hybrid zones are important windows into the evolutionary dynamics of populations, revealing how processes like introgression and adaptation structure population genomic variation. Importantly, they are useful for understanding speciation and how species respond to their environments. Here, we investigate two closely related sea star species, Asterias rubens and A. forbesi, distributed along rocky European and North American coastlines of the North Atlantic, and use genome‐wide molecular markers to infer the distribution of genomic variation within and between species in this group. Using genomic data and environmental niche modelling, we document hybridization occurring between northern New England and the southern Canadian Maritimes. We investigate the factors that maintain this hybrid zone, as well as the environmental variables that putatively drive selection within and between species. We find that the two species differ in their environmental niche breadth; Asterias forbesi displays a relatively narrow environmental niche while conversely, A. rubens has a wider niche breadth. Species distribution models accurately predict hybrids to occur within environmental niche overlap, thereby suggesting environmental selection plays an important role in the maintenance of the hybrid zone. Our results imply that the distribution of genomic variation in North Atlantic sea stars is influenced by the environment, which will be crucial to consider as the climate changes. [ABSTRACT FROM AUTHOR]

Gametic isolation is thought to play an important role in the evolution of reproductive isolation in broadcast‐spawning marine invertebrates. However, it is unclear whether gametic isolation commonly evolves early in the speciation process or only accumulates after other reproductive barriers are already in place. It is also unknown whether gametic isolation is an effective barrier to introgression following speciation. Here, we used whole‐genome sequencing data and multiple complementary phylogenomic approaches to test whether the well‐documented gametic incompatibilities among the strongylocentrotid sea urchins have limited introgression. We quantified phylogenetic discordance, inferred reticulate phylogenetic networks, and applied the Δ statistic using gene tree topologies reconstructed from multiple sequence alignments of protein‐coding single‐copy orthologs. In addition, we conducted ABBA–BABA tests on genome‐wide single nucleotide variants and reconstructed a phylogeny of mitochondrial genomes. Our results revealed strong mito‐nuclear discordance and considerable nonrandom gene tree discordance that cannot be explained by incomplete lineage sorting alone. Eight of the nine species examined demonstrated a history of introgression with at least one other species or ancestral lineage, indicating that introgression was common during the diversification of the strongylocentrotid urchins. There was strong support for introgression between four extant species pairs (Strongylocentrotus pallidus ⇔ S. droebachiensis, S. intermedius ⇔ S. pallidus, S. purpuratus ⇔ S. fragilis, and Mesocentrotus franciscanus ⇔ Pseudocentrotus depressus) and additional evidence for introgression on internal branches of the phylogeny. Our results suggest that the existing gametic incompatibilities among the strongylocentrotid urchin species have not been a complete barrier to hybridization and introgression following speciation. Their continued divergence in the face of widespread introgression indicates that other reproductive isolating barriers likely exist and may have been more critical in establishing reproductive isolation early in speciation. [ABSTRACT FROM AUTHOR]

Understanding the drivers of evolutionary innovation provides a crucial perspective of how evolutionary processes unfold across taxa and ecological systems. It has been hypothesised that the Southern Ocean provided ecological opportunities for novelty in the past. However, the drivers of innovation are challenging to pinpoint as the evolutionary genetics of Southern Ocean fauna are influenced by Quaternary glacial–interglacial cycles, oceanic currents and species ecology. Here we examined the genome‐wide single nucleotide polymorphisms of the Southern Ocean brittle stars Ophionotus victoriae (five arms, broadcaster) and O. hexactis (six arms, brooder). We found that O. victoriae and O. hexactis are closely‐related species with interspecific gene flow. During the late Pleistocene, O. victoriae likely persisted in a connected deep water refugium and in situ refugia on the Antarctic continental shelf and around Antarctic islands; O. hexactis persisted exclusively within in situ island refugia. Within O. victoriae, contemporary gene flow linking to the Antarctic Circumpolar Current, regional gyres and other local oceanographic regimes was observed. Gene flow connecting West and East Antarctic islands near the Polar Front was also detected in O. hexactis. A strong association was detected between outlier loci and salinity in O. hexactis. Both O. victoriae and O. hexactis are associated with genome‐wide increase in alleles at intermediate‐frequencies; the alleles associated with this peak appear to be species specific, and these intermediate‐frequency variants are far more excessive in O. hexactis. We hypothesise that the peak in alleles at intermediate frequencies could be related to adaptation in the recent past, linked to evolutionary innovations of increase in arm number and a switch to brooding from broadcasting, in O. hexactis. [ABSTRACT FROM AUTHOR]

This review considers available data on the composition of the extracellular matrix (ECM) in echinoderms. The connective tissue in these animals has a rather complex organization. It includes a wide range of structural ECM proteins, as well as various proteases and their inhibitors. Members of almost all major groups of collagens, various glycoproteins, and proteoglycans have been found in echinoderms. There are enzymes for the synthesis of structural proteins and their modification by polysaccharides. However, the ECM of echinoderms substantially differs from that of vertebrates by the lack of elastin, fibronectins, tenascins, and some other glycoproteins and proteoglycans. Echinoderms have a wide variety of proteinases, with serine, cysteine, aspartic, and metal peptidases identified among them. Their active centers have a typical structure and can break down various ECM molecules. Echinoderms are also distinguished by a wide range of proteinase inhibitors. The complex ECM structure and the variety of intermolecular interactions evidently explain the complexity of the mechanisms responsible for variations in the mechanical properties of connective tissue in echinoderms. These mechanisms probably depend not only on the number of cross-links between the molecules, but also on the composition of ECM and the properties of its proteins. [ABSTRACT FROM AUTHOR]

Matrikines (MKs) can be a rich source of functional nutrition components and additional therapy, thereby contributing to human health care and reducing the risk of developing serious diseases, including cancer. Currently, functionally active MKs as products of enzymatic transformation by matrix metalloproteinases (MMPs) are used for various biomedical purposes. Due to the absence of toxic side effects, low species specificity, relatively small size, and presence of various targets at the cell membranes, MKs often exhibit antitumor properties and, therefore, are promising agents for antitumor combination therapy. This review summarizes and analyzes the current data on the antitumor activity of MKs of different origins, discusses the problems and prospects for their therapeutic use, and evaluates the experimental results of studying the antitumor properties of MKs from different echinoderm species generated with the help of a complex of proteolytic enzymes from red king crab Paralithodes camtschatica. Special attention is paid to the analysis of possible mechanisms of the antitumor action of various functionally active MKs, products of the enzymatic activity of various MMPs, and the existing problems for their use in antitumor therapy. [ABSTRACT FROM AUTHOR]

Abstract Background Here we release a new version of EchinoDB, EchinoDB v2.0 ( https://echinodb.uncc.edu ). EchinoDB is a database of genomic and transcriptomic data on echinoderms. The initial database consisted of groups of 749,397 orthologous and paralogous transcripts arranged in orthoclusters by sequence similarity. Results The updated version of EchinoDB includes two new major datasets: the RNA-Seq data of the brittle star Ophioderma brevispinum and the high-quality genomic assembly data of the green sea urchin Lytechinus variegatus. In addition, we enabled keyword searches for annotated data and installed an updated version of Sequenceserver to allow Basic Local Alignment Search Tool (BLAST) searches. The data are downloadable in FASTA format. The first version of EchinoDB appeared in 2016 and was implemented in GO on a local server. The new version has been updated using R Shiny to include new features and improvements in the application. Furthermore, EchinoDB now runs entirely in the cloud for increased reliability and scaling. Conclusion EchinoDB serves a user base drawn from the fields of phylogenetics, developmental biology, genomics, physiology, neurobiology, and regeneration. As use cases, we illustrate the function of EchinoDB in retrieving components of signaling pathways involved in the tissue regeneration process of different echinoderms, including the emerging model species Ophioderma brevispinum. Moreover, we use EchinoDB to shed light on the conservation of the molecular components involved in two echinoderm-specific phenomena: spicule matrix proteins involved in the formation of stereom endoskeleton and the tensilin protein that contributes to the capacity of the connective tissues to quickly change its mechanical properties. The genes involved in the former had been previously studied in echinoids, while gene sequences involved in the latter had been previously described in holothuroids. Specifically, we ask (a) if the biomineralization-related proteins previously reported only in sea urchins are also present in other, non-echinoid, echinoderms and (b) if tensilin, the protein responsible for the control of stiffness of the mutable collagenous tissue, previously described in sea cucumbers, is conserved across the phylum.

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Owing to their remarkable physical properties, cellular structures, such as triply periodic minimal surfaces (TPMS), have multidisciplinary and multifunctional applications. Although these structures are observed in nature, examples of TPMS with large length scales in living organisms are exceedingly rare. Recently, microstructure reminiscent of the diamond-type TPMS was documented in the skeleton of the modern knobby starfish Protoreaster nodosus. Here we report a similar microlattice in a 385 Myr old crinoid Haplocrinites, which pushes back the origins of this highly ordered microstructure in echinoderms into the Devonian. Despite the low Mg2+/Ca2+ ratio of the 'calcite' Devonian sea, the skeleton of these crinoids has high-Mg content, which indicates strong biological control over biomineralogy. We suggest that such an optimization of trabecular arrangement additionally enriched in magnesium, which enhances the mechanical properties, might have evolved in these crinoids in response to increased predation pressure during the Middle Palaeozoic Marine Revolution. This discovery illustrates the remarkable ability of echinoderms, through the process of evolutionary optimization, to form a lightweight, stiff and damage-tolerant skeleton, which serves as an inspiration for biomimetic materials. [ABSTRACT FROM AUTHOR]

Sea stars are keystone species and their mass die-offs due to sea star wasting disease (SSWD) impact marine communities and have fueled recent interest in the microbiome of sea stars. We assessed the host specificity of the microbiome associated with three body regions of the sea star Pisaster ochraceus using 16S rRNA gene amplicon surveys of the bacterial communities living on and in Pisaster , their environment, and sympatric marine hosts across three populations in British Columbia, Canada. Overall, the bacterial communities on Pisaster are distinct from their environment and differ by both body region and geography. We identified core bacteria specifically associated with Pisaster across populations and nearly absent in other hosts and the environment. We then investigated the distribution of these core bacteria on SSWD-affected Pisaster from one BC site and by reanalyzing a study of SSWD on Pisaster from California. We find no differences in the distribution of core bacteria in early disease at either site and two core taxa differ in relative abundance in advanced disease in California. Using phylogenetic analyses, we find that most core bacteria have close relatives on other sea stars and marine animals, suggesting these clades have evolutionary adaptions to an animal-associated lifestyle. [ABSTRACT FROM AUTHOR]

The first occurrence of Diadema setosum in the southern Mediterranean waters is recorded from the shores of Libya and Egypt, through the input by citizens' science. The expansion of this invasive sea urchin in the Mediterranean basin is briefly discussed. [ABSTRACT FROM AUTHOR]

Abstract Gametic isolation is thought to play an important role in the evolution of reproductive isolation in broadcast‐spawning marine invertebrates. However, it is unclear whether gametic isolation commonly evolves early in the speciation process or only accumulates after other reproductive barriers are already in place. It is also unknown whether gametic isolation is an effective barrier to introgression following speciation. Here, we used whole‐genome sequencing data and multiple complementary phylogenomic approaches to test whether the well‐documented gametic incompatibilities among the strongylocentrotid sea urchins have limited introgression. We quantified phylogenetic discordance, inferred reticulate phylogenetic networks, and applied the Δ statistic using gene tree topologies reconstructed from multiple sequence alignments of protein‐coding single‐copy orthologs. In addition, we conducted ABBA–BABA tests on genome‐wide single nucleotide variants and reconstructed a phylogeny of mitochondrial genomes. Our results revealed strong mito‐nuclear discordance and considerable nonrandom gene tree discordance that cannot be explained by incomplete lineage sorting alone. Eight of the nine species examined demonstrated a history of introgression with at least one other species or ancestral lineage, indicating that introgression was common during the diversification of the strongylocentrotid urchins. There was strong support for introgression between four extant species pairs (Strongylocentrotus pallidus ⇔ S. droebachiensis, S. intermedius ⇔ S. pallidus, S. purpuratus ⇔ S. fragilis, and Mesocentrotus franciscanus ⇔ Pseudocentrotus depressus) and additional evidence for introgression on internal branches of the phylogeny. Our results suggest that the existing gametic incompatibilities among the strongylocentrotid urchin species have not been a complete barrier to hybridization and introgression following speciation. Their continued divergence in the face of widespread introgression indicates that other reproductive isolating barriers likely exist and may have been more critical in establishing reproductive isolation early in speciation.

Morphological and molecular characterization of cell types, organs and individual organisms is essential for understanding the origins of morphogenesis. The increased implementation of high throughput methods as a means to address cell type evolution, during the last decade, created the need for an efficient way to assess cell type morphology. Here in order to create a new tool to study cell type morphology, we optimized a fast and easy-to-use whole animal freeze-fracture scanning electron microscopy (WAFFSEM) method. This method was applied on marine experimental systems (echinoderms, mollusks, tunicates, and cephalochordates), that have been widely used to assess environmental, developmental, and evolutionary questions. Our protocol does not require any specialized equipment and the processed specimens are compatible with scanning electron microscopy. This protocol was able to successfully expose the internal cell types of all specimens in which it was tested and to reveal their cellular and subcellular characteristics. We strongly believe that the combination of our protocol with other methods (e.g., light microscopy and single cell transcriptomics) will be beneficial to further improve the way to classify and describe cell types.

Holothuria tubulosa Gmelin, 1791 is an edible sea cucumber species widespread in the Mediterranean Sea with ecological and increasing economic importance. Genome data of holothurian species is limited and the availability of genomic data resources is crucial in understanding their biology and adaptability mechanisms. This dataset presents the raw genome sequence data of H. tubulosa sequenced on an Illumina NextSeq 2000 platform. Genome size estimation was performed based on k-mer frequency approach. Additionally, the bacterial microbiome in the stomach and intestine of H. tubulosa collected from the Strymonian Gulf (North Aegean Sea, Greece) through 16S rRNA amplicon metabarcoding sequencing is reported. Sequencing was performed on an Illumina MiSeq platform. Analysis was conducted using the QIIME2 software package, the DADA2 algorithm and a trained classifier for taxonomy assignment. The datasets presented in this work serve as valuable resources for a comprehensive investigation of H. tubulosa at the genome level and for comparative genomics and echinoderms gut microbial studies.

Three new bibenzochromenones named phanogracilins A–C (1–3) were isolated from the crinoid Phanogenia gracilis. The structure of 1 was established using X-ray crystallography as 5,5′,6,6′,8,8′-hexahydroxy-2,2′-dipropyl-4H,4′H-[7,9′-bibenzo[g]chromene]-4,4′-dione. This allowed us to assign reliably 2D NMR signals for compound 1 and subsequently for its isomer 2 that differed in the connecting position of two benzochromenone moieties (7,10′ instead of 7,9′), and compound for 3 that differed in the length of the aliphatic chain of one of the fragments. Compound 4 was derived from 1 in alkaline conditions, and its structure was elucidated as 5,5′,6′,8,8′-pentahydroxy-2,2′-dipropyl-4H,4′H-[7,9′-bibenzo[g]chromene]-4,4′,6,9-tetraone. Even though compounds 1–4 did not contain stereo centers, they possessed notable optical activity due to sterical hindrances, which limited the internal rotation of two benzochromenone fragments around C(7)–C(9′/10′) bonds. Isolated bibenzochromenones 1–4 were tested for their antiradical, neuroprotective and antimicrobial activities. Compounds 1, 3 and 4 demonstrated significant antiradical properties towards ABTS radicals higher than the positive control trolox. Compounds 1 and 4 exhibited moderate neuroprotective activity, increasing the viability of rotenone-treated Neuro-2a cells at a concentration of 1 µM by 9.8% and 11.8%, respectively. Compounds 1 and 3 at concentrations from 25 to 100 μM dose-dependently inhibited the growth of Gram-positive bacteria S. aureus and yeast-like fungi C. albicans, and they also prevented the formation of their biofilms. Compounds 2 and 4 exhibited low antimicrobial activity.

Echinoderms are a marine invertebrate group with important ecological functions in the ocean; they are the source of bioactive compounds, and some species are important for fisheries and aquaculture. Their study in the Colombian Caribbean has focused on taxonomic and ecological aspects and they are a well-documented group of invertebrates. However, small-scale studies of the group are required given the geomorphological and oceanographic diversity along the entire Colombian coastline. The Magdalena River runoff strongly influences the coastal ecosystems of the Department of Atlántico, which has the shortest continental shoreline with only 72 km. The benthic fauna in its surroundings is the biotic component receiving the influence of this river directly, but it has not been the object of deep taxonomic and ecological studies. Field echinoderm surveys were conducted at several sites from 2004 to 2019. Observations and direct collections were carried out from 0 to 5 m depth. We identified four classes, seven orders, eight families, ten genera, and 16 species. Thirteen of these species were first records for Atlántico: Luidia senegalensis, Astropecten articulatus, Amphiodia riisei, Amphiodia trychna, Echinometra lucunter lucunter, Encope michelini, Leodia sexiesperforata, Mellita quinquiesperforata, Isostichopus badionotus, Isostichopus sp., Holothuria grisea, Holothuria glaberrima, and Holothuria princeps. The most frequently observed species were M. quinquiesperforata and H. glaberrima. We provide the local geographic distribution, illustrations, and remarks on each species. This study attempts to close gaps regarding the knowledge of the distribution of marine invertebrates in the Colombian Caribbean Sea.