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The rocky intertidal zone is a paradigmatic ecosystem found along the coastline where the land meets the sea. It holds a plethora of unique animals that fill various niches, creating an atmosphere of constant interactions among both biotic and abiotic factors. The intertidal sea anemone, Anthopleura sola, (A. sola) is dispersed throughout our coastline, making it a widely abundant animal with — surprisingly — limited research done on the species. Our research proposes to examine the ecology of intraspecific aggression among A. sola and how their behaviors influence biological organization at both the individual and population levels. To further understand how habitat-specific factors influence spatial distribution, we will investigate agonistic behaviors that are likely to occur across two different habitats: cobble and bench. We define a cobble habitat as being of loose cobblestone and a bench habitat as a flat, continuous rock substrate. Previous analysis of these habitats from Coal Oil Point, Santa Barbara County, California, suggests that the spatial distribution is influenced by environmental factors and other population-specific characteristics (e.g. density) which may contextualize behavioral traits. A comparative analysis of agonistic behaviors and dietary components will be conducted to better understand how resource availability influences spatial competition. With this information, our study can provide ways to better mitigate the intertidal ecosystems as we experience an increase in environmental changes. This poster was presented at UCSB's 2024 undergraduate research symposium for the department of Ecology, Evolution, and Marine Biology, and received a best poster award.

Fluorescent proteins (FPs) are ubiquitous tools in research, yet their endogenous functions in nature are poorly understood. In this work, we describe a combination of functions for FPs in a clade of intertidal sea anemones whose FPs control a genetic color polymorphism together with the ability to combat oxidative stress. Focusing on the underlying genetics of a fluorescent green "Neon" color morph, we show that allelic differences in a single FP gene generate its strong and vibrant color, by increasing both molecular brightness and FP gene expression level. Natural variation in FP sequences also produces differences in antioxidant capacity. We demonstrate that these FPs are strong antioxidants that can protect live cells against oxidative stress. Finally, based on structural modeling of the responsible amino acids, we propose a model for FP antioxidant function that is driven by molecular surface charge. Together, our findings shed light on the multifaceted functions that can co-occur within a single FP and provide a framework for studying the evolution of fluorescence as it balances spectral and physiological functions in nature.

Germline segregation, essential for protecting germ cells against mutations, occurs during early embryogenesis in vertebrates, insects and nematodes. Highly regenerative animals (e.g., cnidarians), however, retain stem cells with both germinal and somatic potentials throughout adulthood, but their biology and evolution remain poorly understood. Among cnidarians (e.g., sea anemones, jellyfish), stem cells are only known in few hydrozoans (e.g., Hydra). Here, we identify and characterize a rare, multipotent population of stem and/or progenitor cells expressing the conserved germline and multipotency proteins Vasa2 and Piwi1 in the sea anemone Nematostella vectensis. Using piwi1 and vasa2 transgenic reporter lines, we reveal that the Vasa2+/Piwi1+ cell population generates not only gametes, but also a diversity of proliferative somatic cells, including neural progenitors, in juveniles and adults. Our work has uncovered a multipotent population of Vasa2+/Piwi1+ stem/progenitor cells that forms the cellular basis to understand body plasticity and regenerative capacities in sea anemones and corals. Stem or progenitor cells have so far remained elusive in sea anemones or corals. Here, the authors show that a population of cells that express Vasa2 and Piwi1 genes can generate both germ and somatic cells, for example neurons, in a sea anemone. [ABSTRACT FROM AUTHOR]

[Display omitted] Ion channel activation upon ligand gating triggers a myriad of biological events and, therefore, evolution of ligand gating mechanism is of fundamental importance. TRPM2, a typical ancient ion channel, is activated by adenosine diphosphate ribose (ADPR) and calcium and its activation has evolved from a simple mode in invertebrates to a more complex one in vertebrates, but the evolutionary process is still unknown. Molecular evolutionary analysis of TRPM2s from more than 280 different animal species has revealed that, the C-terminal NUDT9-H domain has evolved from an enzyme to a ligand binding site for activation, while the N-terminal MHR domain maintains a conserved ligand binding site. Calcium gating pattern has also evolved, from one Ca2+-binding site as in sea anemones to three sites as in human. Importantly, we identified a new group represented by olTRPM2, which has a novel gating mode and fills the missing link of the channel gating evolution. We conclude that the TRPM2 ligand binding or activation mode evolved through at least three identifiable stages in the past billion years from simple to complicated and coordinated. Such findings benefit the evolutionary investigations of other channels and proteins. [ABSTRACT FROM AUTHOR]

The Venus flytrap sea anemone Actinoscyphia liui inhabits the nutrient‐limited deep ocean in the tropical western Pacific. Compared with most other sea anemones, it has undergone a distinct modification of body shape similar to that of the botanic flytrap. However, the molecular mechanism by which such a peculiar sea anemone adapts to a deep‐sea oligotrophic environment is unknown. Here, we report the chromosomal‐level genome of A. liui constructed from PacBio and Hi‐C data. The assembled genome is 522 Mb in size and exhibits a continuous scaffold N50 of 58.4 Mb. Different from most other sea anemones, which typically possess 14–18 chromosomes per haplotype, A. liui has only 11. The reduced number of chromosomes is associated with chromosome fusion, which likely represents an adaptive strategy to economize energy in oligotrophic deep‐sea environments. Comparative analysis with other deep‐sea sea anemones revealed adaptive evolution in genes related to cellular autophagy (TMBIM6, SESN1, SCOCB and RPTOR) and mitochondrial energy metabolism (MDH1B and KAD2), which may aid in A. liui coping with severe food scarcity. Meanwhile, the genome has undergone at least two rounds of expansion in gene families associated with fast synaptic transmission, facilitating rapid responses to water currents and prey. Positive selection was detected on putative phosphorylation sites of muscle contraction‐related proteins, possibly further improving feeding efficiency. Overall, the present study provides insights into the molecular adaptation to deep‐sea oligotrophic environments and sheds light upon potential effects of a novel morphology on the evolution of Cnidaria. [ABSTRACT FROM AUTHOR]

Most host-parasite associations are explained by phylogenetically conservative capabilities for host utilization, and therefore parasite switches between distantly related hosts are rare. Here we report the first evidence of a parasitic spillover of the burrowing sea anemone Edwardsiella carnea from the invasive ctenophore Mnemiopsis leidyi to two scyphozoan hosts: the native Mediterranean barrel jellyfish Rhizostoma pulmo and the invasive Indo-Pacific nomad jellyfish Rhopilema nomadica, collected from the Eastern Mediterranean Sea. Edwardsiella carnea planulae found in these jellyfish were identified using molecular analyses of the mitochondrial 16S and nuclear 18S rRNA genes. Overall, 93 planulae were found on tentacles, oral arms, and inside of the gastrovascular canals of the scyphomedusae, whereas no infection was observed in co-occurring ctenophores. DNA metabarcoding approach indicated seasonal presence of Edwardsiella sp. in the Eastern Mediterranean mesozooplankton, coinciding with jellyfish blooms in the region. Our findings suggest a non-specific parasitic relationship between Edwardsiella carnea and various gelatinous hosts based on shared functionality rather than evolutionary history, potentially driven by shifts in host availability due to jellyfish blooms. This spillover raises questions about the ecological impacts of parasitism on native and invasive scyphozoan hosts and the potential role of Edwardsiella in controlling their populations. [ABSTRACT FROM AUTHOR]

Zoantharia is an order among the Hexacorallia (Anthozoa: Cnidaria), and includes at least 300 species. Previously reported genomes from scleractinian corals and actiniarian sea anemones have illuminated part of the hexacorallian diversification. However, little is known about zoantharian genomes and the early evolution of hexacorals. To explore genome evolution in this group of hexacorals, here, we report de novo genome assemblies of the zoantharians Palythoa mizigama (Pmiz) and Palythoa umbrosa (Pumb), both of which are members of the family Sphenopidae, and uniquely live in comparatively dark coral reef caves without symbiotic Symbiodiniaceae dinoflagellates. Draft genomes generated from ultra-low input PacBio sequencing totaled 373 and 319 Mbp for Pmiz and Pumb, respectively. Protein-coding genes were predicted in each genome, totaling 30,394 in Pmiz and 24,800 in Pumb, with each set having ∼93% BUSCO completeness. Comparative genomic analyses identified 3,036 conserved gene families, which were found in all analyzed hexacoral genomes. Some of the genes related to toxins, chitin degradation, and prostaglandin biosynthesis were expanded in these two Palythoa genomes and many of which aligned tandemly. Extensive gene family loss was not detected in the Palythoa lineage and five of ten putatively lost gene families likely had neuronal function, suggesting biased gene loss in Palythoa. In conclusion, our comparative analyses demonstrate evolutionary conservation of gene families in the Palythoa lineage from the common ancestor of hexacorals. Restricted loss of gene families may imply that lost neuronal functions were effective for environmental adaptation in these two Palythoa species. [ABSTRACT FROM AUTHOR]

Contemporary symbioses in extreme environments can give an insight into mechanisms that stabilize species interactions during environmental change. The intertidal sea anemone, Anthopleura elegantissima, engages in a nutritional symbiosis with microalgae similar to tropical coral, but withstands more intense environmental fluctuations during tidal inundations. In this study, we compare baseline symbiotic traits and their sensitivity to thermal stress within and among anemone aggregations across the intertidal using a laboratory‐based tank experiment to better understand how fixed genotypic and plastic environmental effects contribute to the successful maintenance of this symbiosis in extreme habitats. High intertidal anemones had lower baseline symbiont‐to‐host cell ratios under control conditions, but their symbionts had higher baseline photosynthetic efficiency compared to low intertidal anemone symbionts. Symbiont communities were identical across all samples, suggesting that shifts in symbiont density and photosynthetic performance could be an acclimatory mechanism to maintain symbiosis in different environments. Despite lower baseline symbiont‐to‐host cell ratios, high intertidal anemones maintained greater symbiont‐to‐host cell ratios under heat stress compared with low intertidal anemones, suggesting greater thermal tolerance of high intertidal holobionts. However, the thermal tolerance of clonal anemones acclimatized to different zones was not explained by tidal height alone, indicating additional environmental variables contribute to physiological differences. Host genotype significantly influenced anemone weight, but only explained a minor proportion of variation among symbiotic traits and their response to thermal stress, further implicating environmental history as the primary driver of holobiont tolerance. These results indicate that this symbiosis is highly plastic and may be able to acclimatize to climate change over ecological timescales, defying the convention that symbiotic organisms are more susceptible to environmental stress. [ABSTRACT FROM AUTHOR]

Animal personalities are characterized by intra‐individual consistency and consistent inter‐individual variability in behaviour across time and contexts. Personalities abound in animals, ranging from sea anemones to insects, arachnids, birds, fish and primates, yet the pathways mediating personality formation and expression remain elusive. Social conditions during the early postnatal period are known determinants of mean behavioural trait expressions later in life, but their relevance in shaping personality trajectories is unknown. Here, we investigated the consequences of early social isolation on adult personality expression in plant‐inhabiting predatory mites Phytoseiulus persimilis. These mites are adapted to live in groups. We hypothesized that transient experience of social isolation early in life, that is, deprivation of any social contact during a sensitive window in the post‐hatching phase, has enduring adverse effects on adult personality expression. Newly hatched mites were transiently reared in isolation or in groups and tested as adults for repeatability of various within‐group behaviours, such as movement patterns and mutual interactions including sociability, defined as the propensity to associate and interact benignly with conspecifics, and activity patterns when alone. Groups composed of individuals with the same or different early‐life experiences were repeatedly videotaped and individual behaviours were automatically analysed using AnimalTA. Social experiences early in life had persistent effects on mean behavioural traits as well as adult personality expression, as measured by intraclass correlation coefficients (indicating repeatability). On average, isolation‐reared females moved at higher speeds, meandered less, kept greater distances from others and had fewer immediate neighbours than group‐reared females. Group‐reared females were highly repeatable in inter‐individual distance, moving speed, meandering and area explored, whereas isolation‐reared females were repeatable only in the number of immediate neighbours. Activity, quantified as the proportion of time spent moving within groups, was only repeatable in group‐reared females, whereas activity, quantified as the proportion of time spent moving when alone, was only repeatable in females reared in isolation. Strikingly, also the early‐life experiences of male mates influenced personality expression of mated females, with isolation‐reared males boosting the repeatability of behavioural traits of group‐reared females. Overall, our study provides evidence that a transient phase of social isolation during a critical period early in life has lasting effects that extend into adulthood, impairing adult personality expression. These effects should cascade upward, changing the phenotypic composition and diversity within populations. [ABSTRACT FROM AUTHOR]

Background: The starlet sea anemone, Nematostella vectensis, is an emerging model organism with a high regenerative capacity, which was recently found to possess an orthologue to the human Leucine Rich Repeat Kinase 2 (LRRK2) gene. Mutations in this gene are the most common cause of inherited Parkinson's Disease (PD), highlighting the importance of understanding its function. Despite two decades of research, however, the function of LRRK2 is not well established. Methods: To investigate the function of LRRKs in Nematostella vectensis, we applied small molecule inhibitors targeting the kinase activity of LRRK2 to examine its function in development, homeostasis and regeneration in Nematostella vectensis. Results: In vivo analyses inhibiting the kinase function of this enzyme demonstrated a role of nvLRRK2 in development and regeneration of N. vectensis. These findings implicate a developmental role of LRRK2 in Nematostella, adding to the expanding knowledge of its physiological function. Conclusions: Our work introduces a new model organism with which to study LRRK biology. We report that LRRK kinase activity is necessary for the development and regeneration of Nematostella. Given the short generation time, genetic trackability and in vivo imaging capabilities, this work introduces Nematostella vectensis as a new model in which to study genes linked to neurodegenerative diseases such as Parkinson's. [ABSTRACT FROM AUTHOR]

Fish species of the genus Amphiprion (Perciformes: Pomacentridae) seek protection from predators among the tentacles of sea anemones as their natural habitat, where they live essentially unharmed from stinging by the host's nematocysts. The skin mucus of these anemonefish has been suggested as a protective mechanism that prevents the discharge of the nematocysts upon contact. Whereas some anemonefish species seem to produce their own protective mucous coating, others may acquire mucus (or biomolecules within) from the sea anemone during an acclimation period. In controlled experiments, we show that Amphiprion ocellaris acclimated successfully to their natural host anemone species Stichodactyla gigantea, and also to Stichodactyla haddoni, and in some cases Heteractis crispa, neither of which are natural host species. No symbiosis was observed for three other anemone species tested, Entacmaea quadricolor, Macrodactyla doreensis, and Heteractis malu. We explored the skin mucous protein profile from naive and experienced A. ocellaris during their acclimation to natural and unnatural host anemones. We confidently report the presence of metabolic and structural proteins in the skin mucus of all samples, likely involved in immunological defense, molecular transport, stress response, and signal transduction. For those anemonefish that established symbiosis, there was a clear increase in ribosomal‐type proteins. We additionally provide evidence for the presence of anemone proteins only in the skin mucus of individuals that established symbiosis. Our results support previous speculation of the role of skin mucous–associated proteins in anemonefish–anemone symbiosis. Further exploration of these mucosal proteins could reveal the mechanism of anemonefish acclimation to host anemones. [ABSTRACT FROM AUTHOR]

Sea anemones are an important source of bioactive compounds with potential pharmacological applications. Their toxins are produced and stored in organelles called nematocysts and act on specific targets, including voltage-gated ion channels. To date, sea anemone toxins have demonstrated effects on voltage-gated sodium and potassium channels, facilitating investigations into the structure and function of these proteins. In this study, we evaluated the effect of Bunodeopsis globulifera sea anemone crude extract, and of a low molecular weight fraction, on voltage-gated sodium and calcium channels within the murine nervous system. Notably, the crude extract led to a significant reduction in total sodium current, while also triggering calcium-dependent glutamate release. Furthermore, the low molecular weight fraction, in particular, enhanced total calcium currents and current density. These findings underscore the existence of sea anemone toxins with diverse mechanisms of action beyond those previously documented. [ABSTRACT FROM AUTHOR]

Sea anemones are venomous animals that rely on their venom for prey capture, defense against predators, and intraspecific competition. Currently, comprehensive molecular and evolutionary analyses of the toxin repertoire for sea anemones are limited by a lack of proteomic data for most species. In this study, proteo-transcriptomic analysis was used to expand our knowledge of the proteinaceous components of sea anemone venom by determining the secreted venom proteome of Calliactis polypus. Electromechanical stimulation was used to obtain the secreted venom of C. polypus. We identified a low complexity proteome that was dominated by toxins with similarity to known neurotoxins, as well as six novel toxin candidates. The novel putative toxin candidates were found to be taxonomically restricted to species from the superfamily Metridioidea. Furthermore, the secreted venom of C. polypus had only three putative toxins in common with the venom of acontia from the same species and little similarity with the secreted venom of closely related species. Overall, this demonstrates that regionalized and lineage-specific variability in toxin abundance is common among sea anemone species. Moreover, the limited complexity of the toxin repertoire found in C. polypus supports the idea that peptide neurotoxins make up the dominant toxin arsenal found in the venom of sea anemones. [ABSTRACT FROM AUTHOR]

Sphingomyelin (SM) is a major sphingolipid in mammalian cells. SM is enriched in the extracellular leaflet of the plasma membrane (PM). Besides this localization, recent electron microscopic and biochemical studies suggest the presence of SM in the cytosolic leaflet of the PM. In the present study, we generated a non-toxic SM-binding variant (NT-EqtII) based on equinatoxin-II (EqtII) from the sea anemone Actinia equina, and examined the dynamics of SM in the cytosolic leaflet of living cell PMs. NT-EqtII with two point mutations (Leu26Ala and Pro81Ala) had essentially the same specificity and affinity to SM as wild-type EqtII. NT-EqtII expressed in the cytosol was recruited to the PM in various cell lines. Super-resolution microscopic observation revealed that NT-EqtII formed tiny domains that were significantly colocalized with cholesterol and N-terminal Lyn. Meanwhile, single molecule observation at high resolutions down to 1 ms revealed that all the examined lipid probes including NT-EqtII underwent apparent fast simple Brownian diffusion, exhibiting that SM and other lipids in the cytosolic leaflet rapidly moved in and out of domains. Thus, the novel SM-binding probe demonstrated the presence of the raft-like domain in the cytosolic leaflet of living cell PMs. [ABSTRACT FROM AUTHOR]

Apoptosis, a major form of programmed cell death, is an essential component of host defense against invading intracellular pathogens. Viruses encode inhibitors of apoptosis to evade host responses during infection, and to support their own replication and survival. Therefore, hosts and their viruses are entangled in a constant evolutionary arms race to control apoptosis. Until now, apoptosis in the context of the antiviral immune system has been almost exclusively studied in vertebrates. This limited phyletic sampling makes it impossible to determine whether a similar mechanism existed in the last common ancestor of animals. Here, we established assays to probe apoptosis in the sea anemone Nematostella vectensis, a model species of Cnidaria, a phylum that diverged approximately 600 million years ago from the rest of animals. We show that polyinosinic:polycytidylic acid (poly I:C), a synthetic long double-stranded RNA mimicking viral RNA and a primary ligand for the vertebrate RLR melanoma differentiation-associated protein 5 (MDA5), is sufficient to induce apoptosis in N. vectensis. Furthermore, at the transcriptomic level, apoptosis related genes are significantly enriched upon poly(I:C) exposure in N. vectensis as well as bilaterian invertebrates. Our phylogenetic analysis of caspase family genes in N. vectensis reveals conservation of all four caspase genes involved in apoptosis in mammals and revealed a cnidarian-specific caspase gene which was strongly upregulated. Altogether, our findings suggest that apoptosis in response to a viral challenge is a functionally conserved mechanism that can be traced back to the last common ancestor of Bilateria and Cnidaria. Author summary: Apoptosis is a programmed cell death mechanism used by vertebrates to efficiently block viral infection. The presence of long double-stranded RNA (dsRNA) in the cytosol is a key feature of DNA and RNA virus replication and is absent from uninfected mammalian host cells. Therefore, the ability to sense and respond to viral dsRNAs is crucial for organismal survival. Indeed, numerous studies in mammals have shown that dsRNA has the capacity to trigger a robust apoptosis as antiviral response. However, such studies were limited to vertebrates, and it remained largely unclear how such systems have evolved. Here, we used the sea anemone Nematostella vectensis, member of phylum Cnidaria (jellyfish, corals, hydroids and sea anemones), to address this topic. We demonstrated that indeed dsRNA is sufficient to induce apoptosis in Nematostella and uncovered a conserved network of genes involved in this process. Further, by comparing the results of gene expression analyses in sea anemones and other diverse animal groups such as oysters and lancelets, we show that apoptosis is prevalent in many animal groups and was already part of the response to dsRNA in the last common ancestor of Cnidaria and most other animals that lived 600 million years ago. [ABSTRACT FROM AUTHOR]

Behavioural syndromes are suites of behaviours that corelate between-individuals but the same behaviours may also show within-individual correlations owing to state dependency or trade-offs. Therefore, overall phenotypic behavioural correlations must be separated into their between- and within-individual components. We investigate how startle response duration (an index of boldness) and time taken to reject an inert item (an index of investigation thoroughness) covary in beadlet sea anemones, Actinia equina. Anemones took longer to reject a more complex item compared to a simpler one, validating this measure of investigation thoroughness. We then quantified between- and within-individual correlations using a Bayesian analysis and an alternative frequentist analysis, which returned the same results. Startle responses decreased with anemone size while thoroughness decreased across repeated observations, indicative of simple learning. For each behaviour, repeatability was significant but relatively low and there was no behavioural syndrome. Rather, the two behaviours showed a negative within-individual correlation in most individuals. Thus, boldness and thoroughness are unlikely to be under correlative selection, and they may instead be expressed independently, in line with the general pattern that cross-contextual behavioural syndromes are comparatively rare. It now appears that this pattern may extend broadly across animal diversity. [ABSTRACT FROM AUTHOR]

The complex morphology of neurons requires precise control of their microtubule cytoskeleton. This is achieved by microtubule-associated proteins (MAPs) that regulate the assembly and stability of microtubules, and transport of molecules and vesicles along them. While many of these MAPs function in all cells, some are specifically or predominantly involved in regulating microtubules in neurons. Here we use the sea anemone Nematostella vectensis as a model organism to provide new insights into the early evolution of neural microtubule regulation. As a cnidarian, Nematostella belongs to an outgroup to all bilaterians and thus occupies an informative phylogenetic position for reconstructing the evolution of nervous system development. We identified an ortholog of the microtubule-binding protein doublecortin-like kinase (NvDclk1) as a gene that is predominantly expressed in neurons and cnidocytes (stinging cells), two classes of cells belonging to the neural lineage in cnidarians. A transgenic NvDclk1 reporter line revealed an elaborate network of neurite-like processes emerging from cnidocytes in the tentacles and the body column. A transgene expressing NvDclk1 under the control of the NvDclk1 promoter suggests that NvDclk1 localizes to microtubules and therefore likely functions as a microtubule-binding protein. Further, we generated a mutant for NvDclk1 using CRISPR/Cas9 and show that the mutants fail to generate mature cnidocytes. Our results support the hypothesis that the elaboration of programs for microtubule regulation occurred early in the evolution of nervous systems. [ABSTRACT FROM AUTHOR]

The sea anemone Exaiptasia diaphana (Aiptasia) is a versatile model in studying cellular mechanisms that govern cnidarian-Symbiodiniaceae symbiosis, the foundation of coral reef ecosystems. Here, we provide a protocol to efficiently dissociate adult Aiptasia tissue into a single-cell suspension using enzymatic digestion. We detail steps including washing animals, dissociating tissue with pronase digestion, and evaluating dissociated single cells using fluorescence imaging. This procedure can be applied to other cnidarians, including coral polyps. For complete details on the use and execution of this protocol, please refer to Jinkerson et al. (2022).1.

Coral growth depends on the partnership between the animal hosts and their intracellular, photosynthetic dinoflagellate symbionts. In this study, we used the sea anemone Aiptasia, a laboratory model for coral biology, to investigate the poorly understood mechanisms that mediate symbiosis establishment and maintenance. We found that initial colonization of both adult polyps and larvae by a compatible algal strain was more effective when the algae were able to photosynthesize and that the long-term maintenance of the symbiosis also depended on photosynthesis. In the dark, algal cells were taken up into host gastrodermal cells and not rapidly expelled, but they seemed unable to reproduce and thus were gradually lost. When we used confocal microscopy to examine the interaction of larvae with two algal strains that cannot establish stable symbioses with Aiptasia, it appeared that both pre- and post-phagocytosis mechanisms were involved. With one strain, algae entered the gastric cavity but appeared to be completely excluded from the gastrodermal cells. With the other strain, small numbers of algae entered the gastrodermal cells but appeared unable to proliferate there and were slowly lost upon further incubation. We also asked if the exclusion of either incompatible strain could result simply from their cells' being too large for the host cells to accommodate. However, the size distributions of the compatible and incompatible strains overlapped extensively. Moreover, examination of macerates confirmed earlier reports that individual gastrodermal cells could expand to accommodate multiple algal cells. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'. [ABSTRACT FROM AUTHOR]

The hermit crab-sea anemone (HCA) partnership is a common facultative mutualism. The anemone protects its host from predators such as cephalopods and shell crushing crabs by its stinging cells. The crab provides the anemone with a hard substrate and increased access to oxygenated water and food and in some cases with protection from predators. These partnerships are extremely diverse and complex. This overview addresses issues related to formation of the associations, the early history of these partnerships, placement of anemones on the hermit crab shell, intra and interspecific competition amongst hermit crabs over sea anemones, costs and benefits for crab and anemone from being associated and the evolution of these partnerships based on molecular phylogenies using nuclear and mitochondrial markers. [ABSTRACT FROM AUTHOR]

Gene duplication is a major force driving evolutionary innovation. A classic example is generating new animal toxins via duplication of physiological protein-encoding genes and recruitment into venom. While this process drives the innovation of many animal venoms, reverse recruitment of toxins into nonvenomous cells remains unresolved. Using comparative genomics, we find members of the Membrane Attack Complex and Perforin Family (MAC) have been recruited into venom-injecting cells (cnidocytes), in soft and stony corals and sea anemones, suggesting that the ancestral MAC was a cnidocyte expressed toxin. Further investigation into the model sea anemone Nematostella vectensis reveals that three members have undergone Nematostella -specific duplications leading to their reverse recruitment into endomesodermal cells. Furthermore, simultaneous knockdown of all three endomesodermally expressed MACs leads to mis-development, supporting that these paralogs have nonvenomous function. By resolving the evolutionary history and function of MACs in Nematostella , we provide the first proof for reverse recruitment from venom to organismal development. [ABSTRACT FROM AUTHOR]

In nearly all animals, light‐sensing mediated by opsin visual pigments is important for survival and reproduction. Eyeless light‐sensing systems, though vital for many animals, have received relatively less attention than forms with charismatic or complex eyes. Despite no single light‐sensing organ, the sea anemone Nematostella vectensis has 29 opsin genes and multiple light‐mediated behaviors throughout development and reproduction, suggesting a deceptively complex light‐sensing system. To characterize one aspect of this light‐sensing system, we analyzed larval swimming behavior at high wavelength resolution across the ultraviolet and visual spectrum. N. vectensis larvae respond to light at least from 315 to 650 nm, which is a broad sensitivity range even compared to many animals with complex eyes. Planktonic swimming is induced by ultraviolet (UV) and violet wavelengths until 420 nm. Between 420 and 430 nm a behavioral switch occurs where at wavelengths longer than 430 nm, larvae respond to light by swimming down. Swimming down toward the substrate is distinct from light avoidance, as animals do not exhibit positive or negative phototaxis at any wavelength tested. At wavelengths longer than 575 nm, animals in the water column take increasingly longer to respond and this behavior is more variable until 650 nm where larval response is no different from the dark, suggesting these longer wavelengths lie outside of their sensitivity range. Larval swimming is the only motile stage in the life history of N. vectensis, and increased planktonic swimming could lead to greater dispersal range in potentially damaging shallow environments with short‐wavelength light exposure. Longer wavelength environments may indicate more suitable substrates for metamorphosis into the polyp stage, where the individual will remain for the rest of its life. Future work will test whether this robust behavior is mediated by multiple opsins. [ABSTRACT FROM AUTHOR]

Natural G-protein-coupled receptors (GPCRs) rarely have an additional transmembrane (TM) helix, such as an artificial TM-linker that can unite two class A GPCRs in tandem as a single-polypeptide chain (sc). Here, we report that three groups of TM-linkers exist in the intervening regions of natural GPCR fusions from vertebrates: (1) the original consensus (i.e., consensus 1) and consensus 2~4 (related to GPCR itself or its receptor-interacting proteins); (2) the consensus but GPCR-unrelated ones, 1~7; and (3) the inability to apply 1/2 that show no similarity to any other proteins. In silico analyses indicated that all natural GPCR fusions from Amphibia lack a TM-linker, and reptiles have no GPCR fusions; moreover, in either the GPCR-GPCR fusion or fusion protein of (GPCR monomer) and non-GPCR proteins from vertebrates, excluding tetrapods, i.e., so-called fishes, TM-linkers differ from previously reported mammalian and are avian sequences and are classified as Groups 2 and 3. Thus, previously reported TM-linkers were arranged: Consensus 1 is [T(I/A/P)(A/S)–(L/N)(I/W/L)(I/A/V)GL(L/G)(A/T)(S/L/G)(I/L)] first identified in invertebrate sea anemone Exaiptasia diaphana (LOC110241027) and (330-SPSFLCI–L–SLL-340) identified in a tropical bird Opisthocomus hoazin protein LOC104327099 (XP_009930279.1); GPCR-related consensus 2~4 are, respectively, (371-prlilyavfc fgtatg-386) in the desert woodrat Neotoma lepida A6R68_19462 (OBS78147.1), (363-lsipfcll yiaallgnfi llfvi-385) in Gavia stellate (red-throated loon) LOC104264164 (XP_009819412.1), and (479-ti vvvymivcvi glvgnflvmy viir-504) in a snailfish GPCR (TNN80062.1); In Mammals Neotoma lepida, Aves Erythrura gouldiae, and fishes protein (respectively, OBS83645.1, RLW13346.1 and KPP79779.1), the TM-linkers are Group 2. Here, we categorized, for the first time, natural TM-linkers as rare evolutionary events among all vertebrates. [ABSTRACT FROM AUTHOR]

Peptide toxins found in sea anemones venom have diverse properties that make them important research subjects in the fields of pharmacology, neuroscience and biotechnology. This study used high-throughput sequencing technology to systematically analyze the venom components of the tentacles, column, and mesenterial filaments of sea anemone Heteractis crispa, revealing the diversity and complexity of sea anemone toxins in different tissues. A total of 1049 transcripts were identified and categorized into 60 families, of which 91.0% were proteins and 9.0% were peptides. Of those 1049 transcripts, 416, 291, and 307 putative proteins and peptide precursors were identified from tentacles, column, and mesenterial filaments respectively, while 428 were identified when the datasets were combined. Of these putative toxin sequences, 42 were detected in all three tissues, including 33 proteins and 9 peptides, with the majority of peptides being ShKT domain, β-defensin, and Kunitz-type. In addition, this study applied bioinformatics approaches to predict the family classification, 3D structures, and functional annotation of these representative peptides, as well as the evolutionary relationships between peptides, laying the foundation for the next step of peptide pharmacological activity research. [ABSTRACT FROM AUTHOR]

Bunodosoma zamponii is the most abundant anemone in Mar del Plata (Buenos Aires, Argentina). Given that the presence of persistent organic pollutants (organochlorine pesticides and PCBs) and the organophosphate pesticide chlorpyrifos has recently been reported in this species, two wild populations living under different anthropogenic pressures were studied and compared regarding basic aspects of their ecology and physiological response to oxidative stress. A population from an impacted site (Las Delicias, LD) and another from a reference site (Punta Cantera, PC) were monitored seasonally (spring, summer, autumn, and winter), for one year. Anemones from PC were larger and more abundant than those from LD for most sampling periods. During winter, glutathione-S-transferase and catalase activities were higher in LD. Moreover, protein content and antioxidant defenses were higher in anemones from PC during winter as well. Taking into account their ecology (size and abundance) and biomarker responses, the population from PC was comparatively healthier. Furthermore, such differences are in agreement with recent studies indicating a higher concentration of pollutants in anemones from LD (specially during the winter sampling). In this sense, considering that B. zamponii can bioaccumulate the aforementioned pollutants, its resilience to their presence, and the fact that biomarker response differed between sites, this species can be regarded as a proper sentinel species of environmental pollution. Overall, this anemone seems to be a good bioindicator to be considered in future biomonitoring and ecotoxicological studies. [ABSTRACT FROM AUTHOR]

Sea anemones are valuable for therapeutic research as a diversified source of bioactive molecules, due to their diverse bioactive molecules linked to predation and defence mechanisms involving toxins and antimicrobial peptides. Acid extracts from Actinia equina tentacles and body were examined for antibacterial activity against Gram-positive, Gram-negative bacteria, and fungi. The peptide fractions showed interesting minimum inhibitory concentration (MIC) values (up to 0.125 µg/mL) against the tested pathogens. Further investigation and characterization of tentacle acid extracts with significant antimicrobial activity led to the purification of peptides through reverse phase chromatography on solid phase and HPLC. Broad-spectrum antimicrobial peptide activity was found in 40% acetonitrile fractions. The resulting peptides had a molecular mass of 2612.91 and 3934.827 Da and MIC ranging from 0.06 to 0.20 mg/mL. Sequencing revealed similarities to AMPs found in amphibians, fish, and Cnidaria, with anti-Gram+, Gram-, antifungal, candidacidal, anti-methicillin-resistant Staphylococcus aureus, carbapenemase-producing, vancomycin-resistant bacteria, and multi-drug resistant activity. Peptides 6.2 and 7.3, named Equinin A and B, respectively, were synthesized and evaluated in vitro towards the above-mentioned bacterial pathogens. Equinin B exerted interesting antibacterial activity (MIC and bactericidal concentrations of 1 mg/mL and 0.25 mg/mL, respectively) and gene organization supporting its potential in applied research. [ABSTRACT FROM AUTHOR]

Background: The recent combination of genomics and single cell transcriptomics has allowed to assess a variety of non-conventional model organisms in much more depth. Single cell transcriptomes can uncover hidden cellular complexity and cell lineage relationships within organisms. The recent developmental cell atlases of the sea anemone Nematostella vectensis, a representative of the basally branching Cnidaria, has provided new insights into the development of all cell types (Steger et al Cell Rep 40(12):111370, 2022; Sebé-Pedrós et al. Cell 173(6):1520–1534.e20). However, the mapping of the single cell reads still suffers from relatively poor gene annotations and a draft genome consisting of many scaffolds. Results: Here we present a new wildtype resource of the developmental single cell atlas, by re-mapping of sequence data first published in Steger et al. (2022) and Cole et al. (Nat Commun 14(1):1747, 2023), to the new chromosome-level genome assembly and corresponding gene models in Zimmermann et al. (Nat Commun 14, 8270 (2023). https://doi.org/10.1038/s41467-023-44080-7). We expand the pre-existing dataset through the incorporation of additional sequence data derived from the capture and sequencing of cell suspensions from four additional samples: 24 h gastrula, 2d planula, an inter-parietal region of the bodywall from a young unsexed animal, and another adult mesentery from a mature male animal. Conclusion: Our analyses of the full cell-state inventory provide transcriptomic signatures for 127 distinct cell states, of which 47 correspond to neuroglandular subtypes. We also identify two distinct putatively immune-related transcriptomic profiles that segregate between the inner and outer cell layers. Furthermore, the new gene annotation Nv2 has markedly improved the mapping on the single cell transcriptome data and will therefore be of great value for the community and anyone using the dataset. [ABSTRACT FROM AUTHOR]

Simple Summary: The unsurmountable diversity of marine life is an invaluable reservoir of natural compounds for drug discovery, amongst which toxins and other bioactive molecules in venoms and poisons are prized targets. Cnidarians are some of the best-studied marine venomous animals, yet most venom components remain unidentified. This study focuses on the sea anemone Actinia equina from Portuguese intertidal zones, comparing two common morphotypes, "green" and "red", ultimately aiming to explore its potential as a source of bioactive compounds. We provide detailed examinations of A. equina's anatomy and microanatomy, a proteomics analysis to identify proteinaceous toxins in its tentacles and toxicity testing on zebrafish embryos. The study confirms the presence of venom-injecting cells (nematocysts) in the tentacles but finds no differences between green and red varieties. Various toxins, including neurotoxins and pore-forming proteins, were discovered. Both green and red extracts exhibit toxicity to zebrafish embryos, with green anemones appearing more potent. Overall, this study unveils proteinaceous toxins in A. equina and demonstrates that different varieties harbour distinct bioactive compounds. Besides ecological considerations, these findings bring further promise to bioprospecting A. equina for novel toxins with potential biotechnological and biomedical interest. The current study investigates the venom-delivery system of green and red morphotypes of the sea anemone Actinia equina to disclose its potential as a source of bioactive compounds. We compared the two morphotypes using electron and optical microscopy, proteomics, and toxicity assessment on zebrafish embryos. Specialized venom-injecting cells (nematocysts) are equally distributed and found in the tentacles of both varieties. Proteomics revealed proteins of interest in both red and green Actinia, yielding the three most abundant Gene Ontology (GO) terms related to the biological processes "proteolysis", "hemolysis in another organism" and "lipid catabolic process". Neurotoxins and cytolytic toxins similar to known cnidarian toxins like PsTX-60A and AvTX-60A, for instance, were identified in both types. Extracts from green and red anemones were toxic to zebrafish embryos, with green anemone venom appearing to be more potent. The findings highlight the presence of proteinaceous toxins in A. equina and the potential for different varieties to possess distinct bioactive compounds. Notably, pore-forming toxins are suggested for molecular probes and immunotoxins, making them valuable assets for potential biotechnological and biomedical purposes. [ABSTRACT FROM AUTHOR]

The ability of an animal to effectively capture prey and defend against predators is pivotal for survival. Venom is often a mixture of many components including toxin proteins that shape predator-prey interactions. Here, we used the sea anemone Nematostella vectensis to test the impact of toxin genotypes on predator-prey interactions. We developed a genetic manipulation technique to demonstrate that both transgenically defficient and a native Nematostella strain lacking a major neurotoxin (Nv1) have a reduced ability to defend themselves against grass shrimp, a native predator. In addition, secreted Nv1 can act indirectly in defense by attracting mummichog fish, which prey on grass shrimp. Here, we provide evidence at the molecular level of an animal-specific tritrophic interaction between a prey, its antagonist, and a predator. Last, this study reveals an evolutionary trade-off, as the reduction of Nv1 levels allows for faster growth and increased reproductive rates. [ABSTRACT FROM AUTHOR]

Cnidarians—the phylum including sea anemones, corals, jellyfish, and hydroids—are one of the oldest groups of predatory animals. Nearly all cnidarians are carnivores that use stinging cells called cnidocytes to ensnare and/or envenom their prey. However, there is considerable diversity in cnidocyte form and function. Tracing the evolutionary history of cnidocytes may therefore provide a proxy for early animal feeding strategies. In this study, we generated a time‐calibrated molecular clock of cnidarians and performed ancestral state reconstruction on 12 cnidocyte types to test the hypothesis that the original cnidocyte was involved in prey capture. We conclude that the first cnidarians had only the simplest and least specialized cnidocyte type (the isorhiza) which was just as likely to be used for adhesion and/or defense as the capture of prey. A rapid diversification of specialized cnidocytes occurred through the Ediacaran (~654–574 million years ago), with major subgroups developing unique sets of cnidocytes to match their distinct feeding styles. These results are robust to changes in the molecular clock model, and are consistent with growing evidence for an Ediacaran diversification of animals. Our work also provides insight into the evolution of this complex cell type, suggesting that convergence of forms is rare, with the mastigophore being an interesting counterexample. Highlights: Cnidarian stinging cells diversified through the Ediacaran, demonstrating that animal predation evolved before the Cambrian explosion. The mastigophore is rare case of a complex cell type evolving more than once. [ABSTRACT FROM AUTHOR]

We report the first records of the sea anemones Anthopleura mariscali, Anthopleura nigrescens, and Exaiptasia diaphana in the Protected Natural Area of Los Cóbanos and Punta Amapala on the coast of El Salvador. Additionally, we extend the known range of distribution of Telmatactis panamensis to southeastern El Salvador. Each of these species is briefly described, and images of live specimens are provided. The geographic distributions of previous records of sea anemones in El Salvador are discussed. An updated list of 11 species reported in the country is provided. [ABSTRACT FROM AUTHOR]

BMP signaling has a conserved function in patterning the dorsal-ventral body axis in Bilateria and the directive axis in anthozoan cnidarians. So far, cnidarian studies have focused on the role of different BMP signaling network components in regulating pSMAD1/5 gradient formation. Much less is known about the target genes downstream of BMP signaling. To address this, we generated a genome-wide list of direct pSMAD1/5 target genes in the anthozoan Nematostella vectensis, several of which were conserved in Drosophila and Xenopus. Our ChIP-seq analysis revealed that many of the regulatory molecules with documented bilaterally symmetric expression in Nematostella are directly controlled by BMP signaling. We identified several so far uncharacterized BMP-dependent transcription factors and signaling molecules, whose bilaterally symmetric expression may be indicative of their involvement in secondary axis patterning. One of these molecules is zswim4-6, which encodes a novel nuclear protein that can modulate the pSMAD1/5 gradient and potentially promote BMP-dependent gene repression. [ABSTRACT FROM AUTHOR]

While the unique symbiotic relationship between anemonefishes and sea anemones is iconic, it is still not fully understood how anemonefishes can withstand and thrive within the venomous environment of their host sea anemone. In this study, we used a proteotranscriptomics approach to elucidate the proteinaceous toxin repertoire from the most common host sea anemone, Entacmaea quadricolor. Although 1251 different toxin or toxin-like RNA transcripts were expressed in E. quadricolor tentacles (0.05% of gene clusters, 1.8% of expression) and 5375 proteins were detected in milked venom, only 4% of proteins detected in venom were putative toxins (230), and they only represent on average 14% of the normalised protein expression in the milked venom samples. Thus, most proteins in milked venom do not appear to have a toxin function. This work raises the perils of defining a dominant venom phenotype based on transcriptomics data alone in sea anemones, as we found that the dominant venom phenotype differs between the transcriptome and proteome abundance data. E. quadricolor venom contains a mixture of toxin-like proteins of unknown and known function. A newly identified toxin protein family, Z3, rich in conserved cysteines of unknown function, was the most abundant at the RNA transcript and protein levels. The venom was also rich in toxins from the Protease S1, Kunitz-type and PLA2 toxin protein families and contains toxins from eight venom categories. Exploring the intricate venom toxin components in other host sea anemones will be crucial for improving our understanding of how anemonefish adapt to the venomous environment. [ABSTRACT FROM AUTHOR]

Cnidarians (corals, sea anemones, and jellyfish) produce toxins that play central roles in key ecological processes, including predation, defense, and competition, being the oldest extant venomous animal lineage. Cnidaria small cysteine-rich proteins (SCRiPs) were the first family of neurotoxins detected in stony corals, one of the ocean's most crucial foundation species. Yet, their molecular evolution remains poorly understood. Moreover, the lack of a clear classification system has hindered the establishment of an accurate and phylogenetically informed nomenclature. In this study, we extensively surveyed 117 genomes and 103 transcriptomes of cnidarians to identify orthologous SCRiP gene sequences. We annotated a total of 168 novel putative SCRiPs from over 36 species of stony corals and 12 species of sea anemones. Phylogenetic reconstruction identified four distinct SCRiP subfamilies, according to strict discrimination criteria based on well-supported monophyly with a high percentage of nucleotide and amino acids' identity. Although there is a high prevalence of purifying selection for most SCRiP subfamilies, with few positively selected sites detected, a subset of Acroporidae sequences is influenced by diversifying positive selection, suggesting potential neofunctionalizations related to the fine-tuning of toxin potency. We propose a new nomenclature classification system relying on the phylogenetic distribution and evolution of SCRiPs across Anthozoa, which will further assist future proteomic and functional research efforts. [ABSTRACT FROM AUTHOR]

The crabs in the subfamily Polydectinae (family Xanthidae) have adapted a defence behaviour in which living invertebrates are used as protection from predators. The polydectine crabs carry a living invertebrate, a sea anemone or nudibranch, in each claw, which is positioned in front of the body and waved to scare off attackers. In an attempt to trace the origin of this behaviour, we sequenced the complete mitochondrial genome of 19 crabs (encompassing 12 genera) from museum samples. The complete mitochondrial genomes were included in a larger dataset with previously published sequences and analysed using maximum likelihood and Bayesian inference. The divergence times of the polydectine crab radiation were estimated using the mitochondrial dataset and fossil calibration points. Our results show that the anemone-carrying polydectine crabs consist of at least three deep evolutionary lineages that evolved in the Late Eocene. All three lineages share the unique behaviour suggesting that it emerged in the ancestor to Polydectinae nearly 40 million years ago and has persisted in all living species. [ABSTRACT FROM AUTHOR]

Cnidarians face significant threats from ocean acidification (OA) and anthropogenic pollutants such as oxybenzone (BP-3). The convergence of threats from multiple stressors is an important area to investigate because of potential significant synergistic or antagonistic interactions. Real-time quantitative PCR was performed to characterize the expression profiles of twenty-two genes of interest (GOI) in sea anemones (Exaiptasia diaphana) exposed to one of four treatments: 1) 96 h of OA conditions followed by a 4 h exposure to 20 ppb BP-3; 2) Exposure to 4 h 20 ppb BP-3 without 96 h of OA; 3) Exposure to 96 h of OA alone; or 4) laboratory conditions with no exposure to BP3 and/or OA. These 22 GOIs represent cellular processes associated with protondependent transport, sodium-dependent transport, metal cation binding/ transport, extracellular matrix, amino acid metabolism/transport, immunity, and/or steroidogenesis. These 22 GOIs provide new insight into vulnerable cellular processes in non-calcifying anthozoans exposed to OA and BP-3. Expression profiles were categorized as synergistic, antagonistic, or additive of BP-3 in the presence of OA. Two GOIs were synergistic. Fifteen GOIs were antagonistic and the remaining five GOIs were additive in response to BP-3 in acidified seawater. A subset of these GOIs appear to be candidate biomarkers for future in situ investigations. In human health, proton-dependent monocarboxylate transporters (MCTs) are promising pharmacological targets and recognized as potential biomarkers. By comparison, these same MCTs appear to be targets of xenobiotic chemical pollutants in cnidarian physiology. In the presence of BP-3, a network of collagen synthesis genes are upregulated and antagonistic in their expression profiles. Cytochrome b561 is a critical protein required for collagen synthesis and in silico modeling demonstrates BP-3 binds in the pocket of cytochrome b561. Understanding the underlying molecular mechanisms of “drug-like” compounds such as BP-3 may lead to a more comprehensive interpretation of transcriptional expression profiles. The collective antagonistic responses of GOIs associated with collagen synthesis strongly suggests these GOIs should be considered candidate biomarkers of effect. GOIs with synergistic and additive responses represent candidate biomarkers of exposure. Results show the effects of OA and BP-3 are interactive with respect to their impact on cnidarians. This investigation offers mechanistic data that supports the expression profiles and underpins higher order physiological responses. [ABSTRACT FROM AUTHOR]

In the deep sea, interactions between benthic fauna and seafloor sediment primarily occur through bioturbation that can be preserved as traces (i.e. lebensspuren). Lebensspuren are common features of deep-sea landscapes and are more abundant than the organisms that produce them (i.e. tracemakers), rendering lebensspuren promising proxies for inferring biodiversity. The density and diversity relationships between lebensspuren and benthic fauna remain unclear, and contradicting correlations have been proposed (i.e. negative, positive, or even null correlations). To approach these variable correlations, lebensspuren and benthic fauna were characterized taxonomically at eight deep-sea stations in the Kuril-Kamchatka Trench area, together with two novel categories: tracemakers (specific epibenthic fauna that produce these traces) and degrading fauna (benthic fauna that can erase lebensspuren). No general correlation (overall study area) was observed between diversities of lebensspuren, tracemakers, degrading fauna, and fauna. However, a diversity correlation was observed at specific stations, showing both negative and positive correlations depending on: (1) the number of unknown tracemakers (especially significant for dwelling lebensspuren); (2) the lebensspuren with multiple origins; and (3) tracemakers that can produce different lebensspuren. Lebensspuren and faunal density were not correlated. However, lebensspuren density was either positively or negatively correlated with tracemaker densities, depending on the lebensspuren morphotypes. A positive correlation was observed for resting lebensspuren (e.g. ophiuroid impressions, Actiniaria circular impressions), while negative correlations were observed for locomotion-feeding lebensspuren (e.g. echinoid trails). In conclusion, lebensspuren diversity may be a good proxy for tracemaker biodiversity when the lebensspuren–tracemaker relationship can be reliable characterized. Lebensspuren–density correlations vary depending on the specific lebensspuren residence time, tracemaker density, and associated behaviour (rate of movement). Overall, we suggest that lebensspuren density and diversity correlations should be studied with tracemakers rather than with general benthic fauna. On a global scale, abiotic (e.g. hydrodynamics, substrate consistency) and other biotic factors (e.g. microbial degradation) may also play an important role. [ABSTRACT FROM AUTHOR]

Cellular dysfunction during Parkinson's disease leads to neuroinflammation in various brain regions, inducing neuronal death and contributing to the progression of the disease. Different ion channels may influence the process of neurodegeneration. The peptides Ms 9a-1 and APHC3 can modulate the function of TRPA1 and TRPV1 channels, and we evaluated their cytoprotective effects in differentiated to dopaminergic neuron-like SH-SY5Y cells. We used the stable neuroblastoma cell lines SH-SY5Y, producing wild-type alpha-synuclein and its mutant A53T, which are prone to accumulation of thioflavin-S-positive aggregates. We analyzed the viability of cells, as well as the mRNA expression levels of TRPA1, TRPV1, ASIC1a channels, alpha-synuclein, and tyrosine hydroxylase after differentiation of these cell lines using RT-PCR. Overexpression of alpha-synuclein showed a neuroprotective effect and was accompanied by a reduction of tyrosine hydroxylase expression. A mutant alpha-synuclein A53T significantly increased the expression of the pro-apoptotic protein BAX and made cells more susceptible to apoptosis. Generally, overexpression of alpha-synuclein could be a model for the early stages of PD, while expression of mutant alpha-synuclein A53T mimics a genetic variant of PD. The peptides Ms 9a-1 and APHC3 significantly reduced the susceptibility to apoptosis of all cell lines but differentially influenced the expression of the genes of interest. Therefore, these modulators of TRPA1 and TRPV1 have the potential for the development of new therapeutic agents for neurodegenerative disease treatment. [ABSTRACT FROM AUTHOR]

An undescribed variety of the green alga Chlorella cf. vulgaris was found living in the octocoral (soft coral) Sarcophyton sp., which also has dinoflagellate zooxanthellae. The green alga is present in very small numbers and is capable of photoheterotrophy based on growth in the presence of an inhibitor of photosynthesis, DCMU, with glycerol provided as a carbon source. The presence of zoochlorellae (Chl a + b), in soft corals appears to have been unsuspected. The easily cultured green alga was unicellular, unflagellated and very small, c. 2 to 6 µm in diameter and had a relatively high Chl b content (Chl b/a = 0.379 ± 0.063). Rapid light curves using PAM fluorometry on the cultured cells showed that Yield vs. irradiance had a low maximum yield (Ymax, 0.388 ± 0.0132; Irradiance ½ point, E½Ymax = 139 ± 11.1 µmol photon m–2 s–1). The overall optimum irradiance (Eopt) for the alga was 314 ± 18.8 µmol photon m–2 s–1. The alga can photosynthesize at 50% or more of the optimum rate from 70 to 900 µmol photon m–2 s–1 but would be severely inhibited under full sunlight. Most naturally occurring low irradiance habitats may have a low median irradiance but are exposed intermittently to very high irradiances and so a relatively high Eopt is advantageous in minimizing photochemical damage. Like the green algal symbiont Elliptochloris marina of sea anemones, Chlorella cf. vulgaris is not exclusively marine: it grows better in freshwater medium where it has different photosynthetic characteristics (higher Ymax, Eopt and ETRmax). Chlorella cf. vulgaris appears to be capable of photoheterotrophy and it is not clear if it is a symbiont, a commensal or a parasite. [ABSTRACT FROM AUTHOR]

Among non-bilaterian animals, a larval apical sensory organ with integrated neurons is only found in cnidarians. Within cnidarians, an apical organ with a ciliary tuft is mainly found in Actiniaria. Whether this apical tuft has evolved independently in Actiniaria or alternatively originated in the common ancestor of Cnidaria and Bilateria and was lost in specific groups is uncertain. To test this hypothesis, we generated transcriptomes of the apical domain during the planula stage of four species representing three key groups of cnidarians: Aurelia aurita (Scyphozoa), Nematostella vectensis (Actiniaria), and Acropora millepora and Acropora tenuis (Scleractinia). We showed that the canonical genes implicated in patterning the apical domain of N. vectensis are largely absent in A. aurita. In contrast, the apical domain of the scleractinian planula shares gene expression pattern with N. vectensis. By comparing the larval single-cell transcriptomes, we revealed the apical organ cell type of Scleractinia and confirmed its homology to Actiniaria. However, Fgfa2 , a vital regulator of the regionalization of the N. vectensis apical organ, is absent in the scleractinian genome. Likewise, we found that FoxJ1 and 245 genes associated with cilia are exclusively expressed in the N. vectensis apical domain, which is in line with the presence of ciliary apical tuft in Actiniaria and its absence in Scleractinia and Scyphozoa. Our findings suggest that the common ancestor of cnidarians lacked a ciliary apical tuft, and it could have evolved independently in the Actiniaria. [ABSTRACT FROM AUTHOR]

Climate change is increasing ocean temperatures and consequently impacts marine life (e.g., bacterial communities). In this context, studying host–pathogen interactions in marine organisms is becoming increasingly important, not only for ecological conservation, but also to reduce economic loss due to mass mortalities in cultured species. In this study, we used Exaiptasia pallida (E. pallida), an anemone, as an emerging marine model to better understand the effect of rising temperatures on the infection induced by the pathogenic marine bacterium Vibrio parahaemolyticus. The effect of temperature on E. pallida was examined at 6, 24, or 30 h after bath inoculation with 108 CFU of V. parahaemolyticus expressing GFP (Vp-GFP) at 27°C (husbandry temperature) or 31°C (heat stress). Morphological observations of E. pallida and their Hsps expression demonstrated heat stress induced increasing damage to anemones. The kinetics of the infections revealed that Vp-GFP were localized on the surface of the ectoderm and in the mucus during the first hours of infection and in the mesenterial filaments thereafter. To better identify the E. pallida cells targeted by Vp-GFP infection, we used spectral flow cytometry. E. pallida cell types were identified based on their autofluorescent properties. corresponding to different cell types (algae and cnidocytes). We identified an AF10 population whose autofluorescent spectrum was identical to that of human monocytes/macrophage, suggesting that this spectral print could be the hallmark of phagocytic cells called “amebocytes’’. AF10 autofluorescent cells had a high capacity to phagocytize Vp-GFP, suggesting their possible role in fighting infection. This was confirmed by microscopy using sorted AF10 and GFP-positive cells (AF10+/GFP+). The number of AF10+/GFP+ cells were reduced at 31°C, demonstrating that increased temperature not only damages tissue but also affects the immune response of E. pallida. In conclusion, our study provides a springboard for more comprehensive studies of immune defense in marine organisms and paves the way for future studies of the dynamics, activation patterns, and functional responses of immune cells when encountering pathogens. [ABSTRACT FROM AUTHOR]

The cnidom and intraspecific variability of cnidae within the small sea anemone Isactinia sp. were verified. The specific cnidae within the cnidom of four discrete morphological structures (tentacle, actinopharynx, mesenterial filaments, and body column) within Isactinia sp. was investigated. Microbasic b‐mastigophores, microbasic p‐mastigophores, basitrichs, microbasic p‐amastigophores, and spirocysts were found in this species. In addition, two morphologically distinct basitrich forms, distinguishable only in a discharged state, were also found, of which basitrichs with the distinctly shorter thread were found predominately only on the body column. The distribution and abundance of cnidae types differed significantly around the body in the sea anemones, as did the length of basitrichs and spirocysts among tissue types. Cnidae length also differed significantly among individuals. Correlations between cnidae length and sea anemone size were variable, whereby cnidae size was significantly negatively correlated to sea anemone size in seven cnidae–tissue combinations, positively correlated in one, and not correlated in two. Linear regression revealed that sea anemone size was able to explain 33%–68% of variation in size of b‐mastigophores, p‐amastigophores, and small basitrichs from within the mesenterial filaments. Correlations were negligible or not significant in remaining cnidae–tissue combinations, however. While providing key taxonomic cnidae information, this study also highlights the variability of cnidae that may occur within a species of Isactinia. [ABSTRACT FROM AUTHOR]

Across diverse taxa, sublethal exposure to abiotic stressors early in life can lead to benefits such as increased stress tolerance upon repeat exposure. This phenomenon, known as hormetic priming, is largely unexplored in early life stages of marine invertebrates, which are increasingly threatened by anthropogenic climate change. To investigate this phenomenon, larvae of the sea anemone and model marine invertebrate Nematostella vectensis were exposed to control (18 ℃) or elevated (24 ℃, 30 ℃, 35 ℃, or 39 ℃) temperatures for 1 h at 3 days post-fertilization (DPF), followed by return to control temperatures (18 ℃). The animals were then assessed for growth, development, metabolic rates, and heat tolerance at 4, 7, and 11 DPF. Priming at intermediately elevated temperatures (24 ℃, 30 ℃, or 35 ℃) augmented growth and development compared to controls or priming at 39 ℃. Indeed, priming at 39 ℃ hampered developmental progression, with around 40% of larvae still in the planula stage at 11 DPF, in contrast to 0% for all other groups. Total protein content, a proxy for biomass, and respiration rates were not significantly affected by priming, suggesting metabolic resilience. Heat tolerance was quantified with acute heat stress exposures, and was significantly higher for animals primed at intermediate temperatures (24 ℃, 30 ℃, or 35 ℃) compared to controls or those primed at 39 ℃ at all time points. To investigate a possible molecular mechanism for the observed changes in heat tolerance, the expression of heat shock protein 70 (HSP70) was quantified at 11 DPF. Expression of HSP70 significantly increased with increasing priming temperature, with the presence of a doublet band for larvae primed at 39 ℃, suggesting persistent negative effects of priming on protein homeostasis. Interestingly, primed larvae in a second cohort cultured to 6 weeks post-fertilization continued to display hormetic growth responses, whereas benefits for heat tolerance were lost; in contrast, negative effects of short-term exposure to extreme heat stress (39 ℃) persisted. These results demonstrate that some dose-dependent effects of priming waned over time while others persisted, resulting in heterogeneity in organismal performance across ontogeny following priming. Overall, these findings suggest that heat priming may augment the climate resilience of marine invertebrate early life stages via the modulation of key developmental and physiological phenotypes, while also affirming the need to limit further anthropogenic ocean warming. [ABSTRACT FROM AUTHOR]

In mammals, cyclic dinucleotides (CDNs) bind and activate STING to initiate an antiviral type I interferon response. CDNs and STING originated in bacteria and are present in most animals. By contrast, interferons are believed to have emerged in vertebrates; thus, the function of CDN signaling in invertebrates is unclear. Here, we use a CDN, 2'3' cyclic guanosine monophosphate-adenosine monophosphate (2'3'-cGAMP), to activate immune responses in a model cnidarian invertebrate, the starlet sea anemone Nematostella vectensis Using RNA sequencing, we found that 2'3'-cGAMP induces robust transcription of both antiviral and antibacterial genes in N. vectensis Many of the antiviral genes induced by 2'3'-cGAMP are homologs of vertebrate interferon-stimulated genes, implying that the interferon response predates the evolution of interferons. Knockdown experiments identified a role for NF-κB in specifically inducing antibacterial genes downstream of 2'3'-cGAMP. Some of these putative antibacterial genes were also found to be induced during Pseudomonas aeruginosa infection. We characterized the protein product of one of the putative antibacterial genes, the N. vectensis homolog of Dae4, and found that it has conserved antibacterial activity. This work suggests that a broad antibacterial and antiviral transcriptional response is an evolutionarily ancestral output of 2'3'-cGAMP signaling in animals.