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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.

Development is a highly dynamic process in which organisms often experience changes in both form and behavior, which are typically coupled to each other. However, little is known about how organismal-scale behaviors such as body contractility and motility impact morphogenesis. Here, we use the cnidarian Nematostella vectensis as a developmental model to uncover a mechanistic link between organismal size, shape, and behavior. Using quantitative live imaging in a large population of developing animals, combined with molecular and biophysical experiments, we demonstrate that the muscular-hydraulic machinery that controls body movement also drives larva-polyp morphogenesis. We show that organismal size largely depends on cavity inflation through fluid uptake, whereas body shape is constrained by the organization of the muscular system. The generation of ethograms identifies different trajectories of size and shape development in sessile and motile animals, which display distinct patterns of body contractions. With a simple theoretical model, we conceptualize how pressures generated by muscular hydraulics can act as a global mechanical regulator that coordinates tissue remodeling. Altogether, our findings illustrate how organismal contractility and motility behaviors can influence morphogenesis.

Anemonia viridis is an abundant and widely distributed temperate sea anemone that can form dense congregations of individuals. Despite the potential severity of its sting, few detailed cases have been reported. We report a case of a severe toxic reaction following an A. viridis sting in a 35-year-old oceanographer. She developed severe pain, itching, redness, and burning sensation, which worsened one week after treatment with anti-inflammatories, antihistamines and corticosteroids. Prompted by this event, and due to the insufficient risk prevention, lack of training for marine-environment users, and lack of research into sting-specific first-aid protocols, we evaluated the cnidocyst response to five different compounds commonly recommended as rinse solutions in first-aid protocols (seawater, vinegar, ammonia, baking soda, and freshwater) by means of the Tentacle Solution Assay. Vinegar and ammonia triggered an immediate and massive cnidocyst discharge after their application and were classified as activator solutions. Baking soda and freshwater were also classified as activator solutions, although with a lower intensity of discharge. Only seawater was classified as a neutral solution and therefore recommended as a rinse solution after A. viridis sting, at least until an inhibitory solution is discovered., Postprint (published version)

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.

In this method paper, we describe protocols for using membrane-tethered peptide toxins (T-toxins) to study the structure/function and biophysics of toxin-channel interactions with two-electrode voltage clamp (TEVC). Here, we show how T-toxins can be used to determine toxin equilibrium affinity, to quantify toxin surface level by enzyme-linked immunosorbent assay (ELISA) and/or single-molecule total internal reflection fluorescence (smTIRF) microscopy, to assess toxin association and dissociations rate, to identify toxin residues critical to binding via scanning mutagenesis, and to study of toxin blocking mechanism. The sea anemone type I (SAK1) toxin HmK and a potassium channel are used to demonstrate the strategies. T-toxins offer experimental flexibility that facilitates studies of toxin variants by mutation of the expression plasmid, avoiding the need to synthesize and purify individual peptides, speeding and reducing the cost of studies. T-toxins can be applied to peptide toxins that target pores or regulatory domains, that inhibit or activate, that are derived from different species, and that bind to different types of ion channels.

Die im Intertidal von Le Cabellou vorkommenden Seeanemonen Actinia fragacea, A. equina und A. prasina zeigen eine auffällige Verteilung nach Größe und Art. Während große Individuen in Bereichen des unteren Eulitorals zu finden sind, häufen sich kleinere Individuen im oberen Eulitoral. Dafür wurden 120 Individuen aus verschiedenen Bereichen des Eulitorals gesammelt und deren Art bestimmt. Nach Vermessung der einzelnen Individuen wurden Versuche zum Territorialverhalten durchgeführt um Rückschlüsse auf die Gründe dieser Verteilung ziehen zu können. Es konnte ein signifikanter Gewichtsunterschied zwischen den Individuen des oberen und des unteren Eulitorals festgestellt werden, der sich nicht durch den Grad der Hydratisierung erklären lässt und sich auch in der Artverteilung wiederspiegelt. Es konnte aufgrund von zu kleiner Stichprobengröße nicht gezeigt werden, dass die Artverteilung durch interspezifisches Artverhalten determiniert ist., The sea anemones Actinia fragacea, A. equina and A. prasina, which occur in the intertidal of Le Cabellou, show a conspicuous distribution according to size and species. While large individuals can be found in areas of the lower eulitoral, smaller individuals accumulate in the upper eulitoral. For this purpose, 120 individuals from different areas of the Eulitoral were collected and their species determined. After measuring the individual individuals, experiments on territorial behavior were carried out in order to be able to draw conclusions about the reasons for this distribution. There was a significant difference in weight between the individuals of the upper and lower eulittal, which cannot be explained by the degree of hydration and is also reflected in the species distribution. Because the sample size was too small, it could not be shown that the species distribution is determined by interspecific species behavior., Peer Reviewed

Pelagia noctiluca is considered the most important jellyfish in the Mediterranean Sea, due to its abundance and the severity of its stings. Despite its importance in marine ecosystems and the health problems caused by its massive arrival in coastal areas, little is known about its early life stages and its cnidome has never been described. This study of the morphological and anatomical features throughout the life cycle identifies four early stages: two ephyra and two metaephyra stages. Ephyra stage 1, newly developed from a planula, has no velar canals, gastric filaments or nematocyst batteries. Ephyra stage 2, has velar canals, a cruciform-shaped manubrium and gastric filaments. Metaephyra stage 3 has eight tentacle buds and nematocyst clusters for the first time. Lastly, in metaephyra stage 4, the eight primary tentacles grow nearly simultaneously, with no secondary tentacles. Complete nematocyst battery patterns gradually develop throughout the later life stages. Four nematocyst types are identified: a-isorhiza, A-isorhiza, O-isorhiza and eurytele. Of these, a-isorhiza and eurytele are the most important throughout the entire life cycle, while A-isorhiza and O-isorhiza have a more important role in advanced stages. All nematocysts show a positive correlation between increasing capsule volumes and increasing body diameter of the ephyrae, metaephyrae, young medusae and adult medusae. In the early stages, the volumes of euryteles in the gastric filaments are larger than those in the exumbrella, indicating that the capsule volume is critical in the absence of marginal tentacles, specialized for feeding. This study provides updated information, the most extensive description to date, including high-resolution photographs and schematic drawings of all the developmental stages in the life cycle of P. noctiluca. Additionally, the first cnidome characterization is provided for each stage to facilitate accurate identification of this species when collected in the water co, Postprint (published version)

Due to increased greenhouse gas emissions, Earth's climate, including that of its oceans, has changed considerably since the industrial revolution. Two effects of climate change are ocean warming and ocean acidification. Ocean warming is caused by the entrapment of infrared radiation due to increased atmospheric CO2. Ocean acidification is the process by which CO2 goes into solution with seawater, thus decreasing the pH. One of the detrimental effects of ocean warming and ocean acidification is the process of bleaching in corals and related cnidarians. Some sea anemones and corals form symbiotic relationships with photosynthetic dinoflagellates of the family Symbiodiniaceae. The dinoflagellates are able to photosynthesize and transfer metabolites to their hosts. Under certain conditions, including elevated sea water temperatures, corals lose their symbiotic dinoflagellates in a process called bleaching. Some corals and anemones turn white or bleach when the symbiosis is lost. Because ocean warming and ocean acidification are simultaneously occurring throughout the world's oceans, I exposed symbiotic anemones, Exaiptasia pallida, formerly known as Aiptasia, to different environments and examined the density of symbiotic dinoflagellates. I placed subjects into a heated treatment, an acidified treatment, and a combined treatment with both heated and acidified water. I assessed the density of dinoflagellates during a two-week bleaching period using chlorophyll fluorometry. I determined the density of dinoflagellates per ?g of protein after the bleaching period using a formulated symbiont assay protocol. Acidification alone did not induce bleaching. The combined treatment resulted in a reduction in dinoflagellate density that was not as steep as that in the heated treatments. This trend, however, was not observed in all trials. There appears to be a complex interaction between ocean warming and ocean acidification that affects the rate at which bleaching occurs in this s

We show here that membrane-tethered toxins facilitate the biophysical study of the roles of toxin residues in K+ channel blockade to reveal two blocking mechanisms in the K+ channel pore. The structure of the sea anemone type I (SAK1) toxin HmK is determined by NMR. T-HmK residues are scanned by point mutation to map the toxin surface, and seven residues are identified to be critical to occlusion of the KcsA channel pore. T-HmK-Lys22 is shown to interact with K+ ions traversing the KcsA pore from the cytoplasm conferring voltage dependence on the toxin off rate, a classic mechanism that we observe as well with HmK in solution and for Kv1.3 channels. In contrast, two related SAK1 toxins, Hui1 and ShK, block KcsA and Kv1.3, respectively, via an arginine rather than the canonical lysine, when tethered and as free peptides.

Actinoporins are a group of soluble toxic proteins that bind to membranes containing sphingomyelin (SM) and oligomerize to form pores. Sticholysin II (StnII) is a member of the actinoporin family, produced by Stichodactyla helianthus. Cholesterol (Chol) is known to enhance the activity of StnII. However, the molecular mechanisms behind this activation have remained obscure, although the activation is not Chol specific but rather sterol specific. To further explore how bilayer lipids affect or are affected by StnII, we have used a multiprobe approach (fluorescent analogs of both Chol and SM) in combination with a series of StnII tryptophan (Trp)-mutants, to study StnII/bilayer interactions. First we compared StnII bilayer permeabilization in the presence of Chol or oleoyl-ceramide (OCer). The comparison was done since both Chol and OCer have a 1-hydroxyl which help to orient the molecule in the bilayer (although OCer have additional polar functional groups). Both Chol and OCer also have increased affinity for SM, which StnII may recognize. However, our results show that only Chol was able to activate StnII-induced bilayer permeabilization – OCer failed to active. To further examine possible Chol/StnII interactions, we measured Förster resonance energy transfer (FRET) between Trp in StnII and cholestatrienol (CTL), a fluorescent analog of Chol. We could show higher FRET efficiency between CTL and Trp:s in position 100 and 114 of StnII, when compared to three other Trp positions further away from the bilayer binding region of StnII. Taken together, our results suggest that StnII was able to attract Chol to its vicinity, maybe by showing affinity for Chol. SM interactions are known to be important for StnII binding to bilayers, and Chol is known to facilitate subsequent permeabilization of the bilayers by StnII. Our results help to better understand the role of these important membrane lipids for the bilayer properties of StnII., Banco Santander-UCM, Depto. de Bioquímica y Biología Molecular, Fac. de Ciencias Químicas, TRUE, pub

BACKGROUND: The ability to efficiently visualize and manipulate chromosomes is fundamental to understanding the genome architecture of organisms. Conventional chromosome preparation protocols developed for mammalian cells and those relying on species-specific conditions are not suitable for many invertebrates. Hence, a simple and inexpensive chromosome preparation protocol, adaptable to multiple invertebrate species, is needed. RESULTS: We optimized a chromosome preparation protocol and applied it to several planarian species (phylum Platyhelminthes), the freshwater apple snail Pomacea canaliculata (phylum Mollusca), and the starlet sea anemone Nematostella vectensis (phylum Cnidaria). We demonstrated that both mitotically active adult tissues and embryos can be used as sources of metaphase chromosomes, expanding the potential use of this technique to invertebrates lacking cell lines and/or with limited access to the complete life cycle. Simple hypotonic treatment with deionized water was sufficient for karyotyping; growing cells in culture was not necessary. The obtained karyotypes allowed the identification of differences in ploidy and chromosome architecture among otherwise morphologically indistinguishable organisms, as in the case of a mixed population of planarians collected in the wild. Furthermore, we showed that in all tested organisms representing three different phyla this protocol could be effectively coupled with downstream applications, such as chromosome fluorescent in situ hybridization. CONCLUSIONS: Our simple and inexpensive chromosome preparation protocol can be readily adapted to new invertebrate research organisms to accelerate the discovery of novel genomic patterns across the branches of the tree of life.

Some corals and sea anemones form obligate symbiotic relationships with photosynthetic dinoflagellates of the genus Symbiodinium. Ocean warming and ocean acidification related to anthropogenic climate change have the potential to alter this relationship and contribute to bleaching events in which the symbionts are expelled from their hosts. Using the symbiotic anemone Exaiptasia pallida, I examined the effects of projected future climate conditions on this relationship. I exposed symbiotic anemones to one of three treatments: warmed waters, waters acidified by the addition of carbon dioxide, or warmed and acidified waters. I monitored symbiont loss using a combination of chlorophyll fluorometry and fluorescence microscopy. In addition to observed variation in bleaching response between anemones in the heated and in the combined heated and acidified treatments, there was also variation across trials. Anemones in the acidified treatment did not exhibit any signs of bleaching. These results suggest that there is a complex interaction between the effects of ocean warming and ocean acidification on this symbiotic relationship.

Cilia are organelles specialized for movement and signaling. To infer when during evolution signaling pathways became associated with cilia, we characterized the proteomes of cilia from sea urchins, sea anemones, and choanoflagellates. We identified 437 high-confidence ciliary candidate proteins conserved in mammals and discovered that Hedgehog and G-protein-coupled receptor pathways were linked to cilia before the origin of bilateria and transient receptor potential (TRP) channels before the origin of animals. We demonstrated that candidates not previously implicated in ciliary biology localized to cilia and further investigated ENKUR, a TRP channel-interacting protein identified in the cilia of all three organisms. ENKUR localizes to motile cilia and is required for patterning the left-right axis in vertebrates. Moreover, mutation of ENKUR causes situs inversus in humans. Thus, proteomic profiling of cilia from diverse eukaryotes defines a conserved ciliary proteome, reveals ancient connections to signaling, and uncovers a ciliary protein that underlies development and human disease.

Summary: The sea anemone Aiptasia pallida is a biological model for anthozoan research. Like all cnidarians, A. pallida possesses nematocysts for food capture and defense. Studies have shown that anthozoans, such as corals, can rapidly increase nematocyst concentration when faced with competition or predation, suggesting that nematocyst production may be an induced trait. The potential effects of two types of tissue damage, predator induced (Lysmata wurdemanni) and artificial (forceps), on nematocyst concentration was assessed. Nematocysts were identified by type and size to examine the potential plasticity associated with nematocyst production. While no significant differences were found in defensive nematocyst concentration between shrimp predation treatments versus controls, there was a significant difference in small-sized nematocyst in anemones damaged with forceps. The proportions of the different types of nematocysts between treatment types were also found to be different suggesting that nematocyst production in A. pallida is a plastic trait., 2014, Includes bibliography., Degree granted: Thesis (M.S.)--Florida Atlantic University, 2014., Collection: FAU Electronic Theses and Dissertations Collection

Predators capture prey in complex and variable environments. In the ocean, bottom- dwelling (benthic) organisms are subjected to water currents, waves, and turbulent eddies. For benthic predators that feed on small animals carried in the water (zooplankton), flow not only delivers prey, but can also shape predator-prey interactions. Benthic passive suspension feeders collect prey delivered by movement of ambient water onto capture-surfaces, without actively generating feeding currents. What are the characteristics of flow over benthic suspension feeders and how do these vary over time? How do the environmental fluctuations in flow affect the encounter, capture, and retention of motile zooplanktonic prey (copepods, Acartia spp.; nauplii, Artemia spp.) by passive benthic suspension feeders (sea anemones, Anthopleura elegantissima)? For suspension feeders that can dominate the rocky intertidal, how does the presence of neighbors impact feeding by downstream sea anemones? In Chapter One, I quantify water flow over sea anemones found in a wave-exposed and a wave-protected site. I measured variations in flow habitat using a high-frequency instrument (an acoustic Doppler velocimeter) deployed at many temporal scales to assess the range of conditions in which benthic suspension feeders live. I compare the flow habitat over sea anemones between sites, between heights above the substratum, between the flood and ebb of a daily tidal cycle, the spring and neap of a monthly tidal phase, and between onshore and offshore measures of flow conditions. I show that temporal variation is not as significant a factor as spatial variation between two sea anemone clones, and that waves dominate the flow environment. I found that microhabitats over benthic organisms were disrupted or eroded by incoming waves, so that the velocity over organisms at the leading edge of a rocky intertidal shelf could be estimated using free-stream flow. And I discuss how the offshore measurements of wave heigh

Background:Rising sea temperatures are causing significant destruction to coral reef ecosystems due to coral mortality from thermally-induced bleaching (loss of symbiotic algae and/or their photosynthetic pigments). Although bleaching has been intensively studied in corals, little is known about the causes and consequences of bleaching in other tropical symbiotic organisms.Methodology/Principal Findings:This study used underwater visual surveys to investigate bleaching in the 10 species of anemones that host anemonefishes. Bleaching was confirmed in seven anemone species (with anecdotal reports of bleaching in the other three species) at 10 of 19 survey locations spanning the Indo-Pacific and Red Sea, indicating that anemone bleaching is taxonomically and geographically widespread. In total, bleaching was observed in 490 of the 13,896 surveyed anemones (3.5%); however, this percentage was much higher (19-100%) during five major bleaching events that were associated with periods of elevated water temperatures and coral bleaching. There was considerable spatial variation in anemone bleaching during most of these events, suggesting that certain sites and deeper waters might act as refuges. Susceptibility to bleaching varied between species, and in some species, bleaching caused reductions in size and abundance.Conclusions/Significance:Anemones are long-lived with low natural mortality, which makes them particularly vulnerable to predicted increases in severity and frequency of bleaching events. Population viability will be severely compromised if anemones and their symbionts cannot acclimate or adapt to rising sea temperatures. Anemone bleaching also has negative effects to other species, particularly those that have an obligate relationship with anemones. These effects include reductions in abundance and reproductive output of anemonefishes. Therefore, the future of these iconic and commercially valuable coral reef fishes is inextricably linked to the ability of host

Reef fishes exhibit a bipartite life cycle where a benthic adult stage is preceded by a pelagic dispersal phase during which larvae are presumed to be mixed and transported by oceanic currents. Genetic analyses based on twelve microsatellite loci of 181 three-spot dascyllus (Dascyllus trimaculatus) that settled concurrently on a small reef in French Polynesia revealed 11 groups of siblings (1 full sibs and 10 half-sibs). This is the first evidence that fish siblings can journey together throughout their entire planktonic dispersal phase (nearly a month long for three-spot dascyllus). Our findings have critical implications for the dynamics and genetic structure of fish populations, as well as for the design of marine protected areas and management of fisheries.

Twentysix species of sea anemones (Actiniaria) collected in Galicia, northwestern Spain are present in the collection of the Netherlands Centre for Biodiversity Naturalis. They are listed and discussed. The cnidom of seventeen species is surveyed. Diadumene cincta is not a recent immigrant in western Europe. Sagartia luciae is (re)assigned to the genus Diadumene. The presence of Sagartia troglodytes in the Mediterranean is doubtful at best.

Increased ocean acidity because of global warming has the potential to cause coral to bleach. Bleaching, or the loss of symbiotic dinoflagellates by coral and sea anemones, has also been linked to increased temperature and increased irradiance. Bleaching is caused by photoinhibition or the breakdown of the photosynthetic mechanism of the symbiotic zooanthellae of the corals and sea anemones. In this experiment, I explored the potential effects of anthropogenic carbon dioxide on the sea anemone, Aiptasia pallida. I hypothesized that individuals of the sea anemone Aiptasia pallida would bleach when exposed to artificial sea water with decreased pH. I bubbled CO2 through artificial sea water and set up three treatment groups (pH 8.1, pH 7.8, and pH 7.4). Contrary to my hypothesis, the anemones only bleached significantly when exposed to the pH 7.4 treatment level. While all anemones used in the experiment appeared smaller and generally less healthy than anemones maintained in an aquarium, this difference was most prominent in the pH 7.4 treatment level. My results indicate that the pH 7.8 treatment level may actually aid the vitality of the zooxanthellae and subsequently the anemone itself by providing the zooxanthellae with extra CO2 for photosynthesis.

In examining large acontia b-mastigophore and p-amastigophore nematocysts of the sea anemone Metridium senile (Linnaeus, 1761) darts were observed by interference-contrast light microscopy (LM) and scanning electron microscopy (SEM). The darts consist of closely packed spines detached from the shafts, still in three helical rows. Their spines form a hollow cylinder with a sharp tip and indented base, its width similar to that of an undischarged shaft but varying in length. b-mastigophore darts were more common than those of p-mastigophores and many were longer.

Summary: The sea anemone Bartholomea annulata, is an ecologically important member of Caribbean coral reefs. This anemone serves as symbiotic host to crustacean associates, some of which may control parasite loads by "cleaning" reef fishes. Associates may gain protection from predation by dwelling with anemones. B. annulata was the most abundant anemone documented on three reefs, with 52% host to crustacean symbionts. Of those occupied by multi-species groups, 92% included Alpheus armatus shrimp. A. armatus is an important anemone associate providing protection to the anemone from predators such as Hermodice carunculata, in laboratory and field trials. H. carunculata can completely devour or severely damage prey anemones. Here I show that anemones hosting symbiotic alpheid shrimp are extremely less likely to sustain damage by predators than solitary anemones. The role of protector may be reciprocally provided by anemone and decapod associates., by Amber McCammon., Thesis (M.S.)--Florida Atlantic University, 2010., Includes bibliography., Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

Anthopleura aureoradiata, a common sea anemone of New Zealand's intertidal mudflats and rocky shores, hosts symbiotic dinoflagellates of the genus Symbiodinium. This study investigated the control of photosynthetic carbon translocation in this symbiosis, and in particular the presence and operation of socalled 'host release factor' (HRF). Evidence for HRF exists in a number other algalinvertebrate symbioses, where tissue extracts of the host stimulate carbon release by isolated algal symbionts. However, its identity remains elusive and it has never been studied before in A. aureoradiata. Translocation of photosynthetically-fixed carbon in the intact symbiosis and in the presence of host tissue extract was measured using a 14C label. Zooxanthellae in the intact symbiosis released around 40% of their photosynthetically-fixed carbon to the anemone. Isolated zooxanthellae, however, translocated only 8%, even less than the amount of photosynthate liberated by zooxanthellae in FSW alone (11%). Photosynthetic rates per algal cell were similar in the intact symbiosis and both host homogenate and FSW incubations, meaning that the total amount of photosynthetically-fixed carbon released (in pg C/cell/h) by the zooxanthellae in these different situations reflected the %translocation values. Given the failure of homologous zooxanthellae (i.e. those from A. aureoradiata) to respond to homogenized host tissue, it was tested whether zooxanthellae from other host species (i.e. cultured heterologous algae) responded. Heterologous zooxanthellae representing 5 clades (A-E) of Symbiodinium were incubated in host tissue homogenate and photosynthate release again measured with 14C. The %translocation varied from 12-51% in A. aureoradiata homogenate and 17-67% in FSW, again suggesting a lack of an active HRF in the homogenized tissues of this sea anemone. Photosynthetic rates amongst the different heterologous algae also varied widely with, for instance, freshly isolated zooxanthellae fro

This study investigated the potential for, and efficiency of, particulate nitrogen uptake from the sediment and subsequent consequences of this on the nutrient status of endosymbiotic dinoflagellates (zooxanthellae) in the temperate zooxanthellate anemone Anthopleura aureoradiata. Sediment was collected from a mudflat and labelled with (15NH4)2SO4 before being provided to A. aureoradiata at low (5 g dry weight) and high sediment (20 g dry weight) loads for 6 hours. While no discernible change in the isotopic content of the sediment could be detected, analysis of the host and algal symbionts revealed that 15N had been taken up. Uptake by the host was similar at both high and low sediment loads, but the algal symbionts acquired more nitrogen at the lower load (1.13 versus 0.93 atom % 15N in the low and high loads, respectively). Evaluation of this particulate nitrogen uptake from the sediment was further examined by measuring the nitrogen status of the zooxanthellae. This was determined by measuring the extent to which ammonium (40 muM NH+4) enhanced the rate of zooxanthellar dark carbon fixation above that seen in filtered seawater (FSW) alone; the enhancement ratio was expressed as [dark NH+4 rate/dark FSW rate]. VD'/VL, a further index of nitrogen status, was also calculated where VD' = [dark NH+4 rate - dark FSW rate] and VL = rate of carbon fixation in the light. When anemones were starved for 2-8 weeks, zooxanthellar nitrogen deficiency became apparent at greater than or equal to 4 weeks, with NH+4/FSW and VD'/VL averaging up to 2.90 and 0.11, respectively. In comparison, when anemones were fed 5 times per week for 8 weeks the addition of ammonium had little effect, indicating nitrogen sufficiency; NH+4/FSW and VD'/VL values were 1.03 and -1.0 x 10-3, respectively. The nitrogen status of zooxanthellae from anemones starved and incubated with and without sediment was examined with no apparent difference between sediment and no sediment treatments; zooxanthellar n

This study investigated the algal density and growth, photophysiology and contribution of algae to animal respiration requirements (CZAR), in the symbiosis between the sea anemone Anthopleura aureoradiata and its dinoflagellate symbionts (zooxanthellae) under field and laboratory conditions. A. aureoradiata was collected during summer and winter on sunny and cloudy days from a rocky shore and mudflat environment. Algal densities displayed a trend of being 2.6 and 1.7 times greater during summer than winter on the mudflat on a sunny and cloudy day respectively. Algal division was asynchronous under field conditions over a daily period, and was 2.1 and 1.3 times greater on the rocky shore and mudflat respectively, during winter than summer on sunny days. Under field conditions, the efficiency and maximum rate of photosynthesis (per cell and per association) as well as respiration rate, were all greater during summer than winter. Cloud cover resulted in a difference in a higher maximum rate of photosynthesis per cell on a sunny day than a cloudy day within summer at Kau Bay. Additionally, these photosynthetic parameters and respiration rate were all greater on the rocky shore than mudflat while the photosynthetic compensation irradiance was greater on the mudflat. The CZAR was greatest on the rocky shore during summer on a sunny day (151%) and was also > 100% on a cloudy day in summer at this same site (129%); on the mudflat the CZAR was greatest during summer on a sunny day (89%). The CZAR was measured to be zero during winter at both sites during winter on cloudy days. Additionally, under laboratory conditions A. aureoradiata was exposed to gradual (GTC) and rapid (RTC) temperature changes. While under GTC and RTC, the algal density did not vary, though higher temperatures led to an increase in algal division. Under both GTC and RTC, the photosynthetic efficiency, maximum photosynthetic rate (per cell and per association) and respiration rate all increased with tempe

The structure of the actinoporin sticholysin II (StnII) in the pore state was investigated by Fourier transform infrared spectroscopy in the attenuated total reflection configuration. 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/cholesterol unilamellar vesicles were employed. The alpha-helix content increases in approximately 30% upon lipid binding, which agrees with an extension of eight or nine residues at the N-terminal helix. Furthermore, analyses of dichroic spectra show that the extended N-terminal helix would have a 31 degrees tilt with respect to the membrane normal. The orientation of the central beta-sandwich was also estimated. In addition, it was detected that StnII alters the orientation of the lipid acyl chains. (1)H/(2)H exchange experiments sustain a mainly superficial interaction between StnII and the membrane, with no protection of the beta-sandwich. The implications of the results in the mechanism of pore formation are discussed., Comparative Study, Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

The present study of the biogeography of the Antarctic sea anemone fauna is based on new records and redescriptions of material collected from the Weddell Sea and Peninsula Antarctica, and on an update of the bibliographic data of the Antarctic and sub-Antarctic regions. The faunal compositions at different levels, the geographic and bathymetric distributions of the sea anemone fauna, and the affinities within the continent and with the sub-Antarctic fauna have been studied. Furthermore, the relationships of the sea anemone fauna, of the Southern Ocean, the Mediterranean Sea and Hawaii have been analysed. In this context, the origin of the Antarctic benthic fauna is discussed

The locomotory behaviour and functional morphology of English populations of a small (<2 cm long), burrowing athenarian sea anemone, Nematostella vectensis Stephenson, 1935 (= N. pellucida Crowell, 1946), which lives in soft mud in salt marshes and creeks, are described. Objectives were to ascertain the specific stimuli and environmental conditions determining when and how locomotion is employed, and to assess survival values. Experimentation and anatomical examination revealed how anemones move, and their functional morphology was interpreted in a physiological context. Finally, locomotion, morphology and habitat were compared for several athenarian anemones, to ascertain what correlations there are, if any. Essential environmental conditions for N. vectensis are: thixotropic mud of median particle size about 30 μm; a well defined oxidizing layer at the mud surface; and well oxygenated water overlying the mud. N. vectensis cannot burrow in sand. The ability to burrow in fine mud is the primary requirement for survival, providing a stable substrate for protection, feeding and reproduction. Anemones are forced to vacate their burrows if oxygen tension in the mud becomes lowered. Rarely, individuals adhere to underwater vegetation, which they reach by climbing. Locomotion in N. vectensis comprises burrowing of two types (penetrative and intrasubstrate), creeping and climbing. Penetrative burrowing, creeping or climbing (the animal progressing physa first), are all facilitated by the complementary deployment of direct peristaltic muscular waves passing down the column and the adhesive properties of the rugae on the column. If the anemone is lying on mud, penetrative burrowing ensues; if on an impenetrable surface, creeping or climbing ensues; these behaviours are not affected by light. At 21°C, in anemones 3-10 mm long, peristaltic waves are initiated about every 54 s at the mid-level of the actinopharynx. Waves progress to the tip of the physa at a mean speed of about

The oral disc of an actinodendronid sea anemone is drawn out into a variable number of highly branched tentacular structures that make the anemone resemble a tree. These tentacular structures have been considered either lobes or branched tentacles. The term lobe has been applied to various structures of the oral disc in sea anemones; I distinguish between temporary lobes, permanent marginal lobes, and permanent tentacular lobes. I use the number of mesenterial pairs involved in a tentacular structure as evidence that tentacular structures in Actinodendronidae should be considered tentacles, not lobes. According to this interpretation, actinodendronids have only one tentacle communicating with each intermesenterial space, both endocoels and exocoels. The similarity between tentacular structures in members of Actinodendronidae and Thalassianthidae is only superficial; the tentacular structures in these families are not homologues as they have been previously considered.

The long-used scientific name of the common European sea-enemone Adamsia palliata should be retained in use and an unfamiliar name used in some recent synoptic works should be abandoned. We show this to be so under the Code of Zoological Nomenclature and also on pragmatic grounds.

Summary: Bleaching of reef corals and other cnidarians symbiotic with zooxanthellae can be attributed to the stress response of the host, algae or both. To determine if zooxanthellae are involved in the bleaching process, I infected a single strain of sea anemone, Aiptasia pallida with zooxanthellae from different hosts. I measured expulsion of the algae from the host during 24-hour incubations at 25, 32 and 34C, as well as photosynthetic rates at these temperatures. Photosynthesis and expulsion of zooxanthellae were inversely and directly proportional to elevated temperatures, respectively. Photosynthesis and expulsion of zooxanthellae isolated from Condylactis gigantea showed the greatest sensitivity to elevated temperature when compared to other zooxanthellae tested. These results suggest that zooxanthellae have a function in the bleaching process and that this function may be related to their photosynthetic response. Thus, the differential tolerance of zooxanthellae to stress could partly explain the spatial variability characteristic of coral-bleaching episodes., Charles E. Schmidt College of Science, Thesis (M.S.)--Florida Atlantic University, 1999.

Summary: Many marine organisms possess endosymbiotic dinoflagellates called zooxanthellae. Bleaching is the loss of zooxanthellae, but bleached hosts can be repopulated. Little is known about how repopulation is controlled. The sea anemone Aiptasia pallida was used to study the effects of feeding on repopulation. Two groups of aposymbiotic anemones were reinfected with algae from symbiotic clones. One group was fed and the other starved, and counts of algae within each anemone were made at 3 day intervals for 6 weeks. The experiment was repeated, and results showed that the rate of algal growth did not differ between fed and starved groups. However, starved anemones reached plateau more quickly and lost algal cells after plateau was reached, whereas fed anemones contained more algae and protein. This suggests that starved anemones can support an algal population initially, but cannot maintain it. Space and nutrients are implicated in having a limiting effect on maintenance of symbionts., Thesis (M.S.)--Florida Atlantic University, 1997.

Using oligonucleotide probes derived from consensus sequences for glycoprotein hormone receptors, we have cloned an 831-amino acid residue-long receptor from Drosophila melanogaster that shows a striking structural homology with members of the glycoprotein hormone (thyroid-stimulating hormone (TSH); follicle-stimulating hormone (FSH); luteinizing hormone/choriogonadotropin (LH/CG)) receptor family from mammals. This homology includes a very large, extracellular N terminus (20% sequence identity with rat TSH, 19% with rat FSH, and 20% with the rat LH/CG receptor) and a seven-transmembrane region (53% sequence identity with rat TSH, 50% with rat FSH, and 52% with the rat LH/CG receptor). The Drosophila receptor gene is >7.5 kilobase pairs long and contains 17 exons and 16 introns. Seven intron positions coincide with introns in the mammalian glycoprotein hormone receptor genes and have the same intron phasing. This indicates that the Drosophila receptor is evolutionarily related to the mammalian receptors. The Drosophila receptor gene is located at position 90C on the right arm of the third chromosome. The receptor is strongly expressed starting 8-16 h after oviposition, and the expression stays high until after pupation. Adult male flies express high levels of receptor mRNA, but female flies express about 6 times less. The expression pattern in embryos and larvae suggests that the receptor is involved in insect development. This is the first report on the molecular cloning of a glycoprotein hormone receptor family member from insects.

Neuropeptides are an important group of hormones mediating or modulating neuronal communication. Neuropeptides are especially abundant in evolutionarily "old" nervous systems, such as those of cnidarians, the lowest animal group having a nervous system. Cnidarians often have a life cycle including a polyp, a medusa, and a planula larva stage. Recently, a neuropeptide,

Antho-KAamide (L-3-phenyllactyl-Phe-Lys-Ala-NH2) and Antho-RIamide (L-3-phenyllactyl-Tyr-Arg-Ile-NH2) are novel neuropeptides isolated from the sea anemone Anthopleura elegantissima. They both inhibited spontaneous contractions of isolated muscle preparations from a wide variety of anemone species (threshold around 10(-7) M). Their actions were universal in that they inhibited every muscle preparation tested, regardless of whether the muscle group was located in the ectoderm or endoderm, or was oriented in a circular or longitudinal direction. Injection of Antho-KAamide or Antho-RIamide into the coelenteron of intact sea anemones resulted in a marked expansion of the animals. Similar shape changes followed feeding or exposure to soluble food extracts. Therefore, we hypothesize that nerve cells that release Antho-KAamide and Antho-RIamide are involved in the expansion phase of feeding behaviour in sea anemones.

Using oligonucleotide probes derived from consensus sequences of known vertebrate and invertebrate G protein-coupled receptors, we have cloned the cDNA for a presumed G protein-coupled receptor from sea anemones. This receptor shows a striking structural homology with members of the glycoprotein hormone (FSH, TSH, LH/CG) receptor family from mammals, including a very large, extracellular N terminus (18-25% sequence identity) and a 7 transmembrane region (44-48% sequence identity). As with the mammalian glycoprotein hormone receptor genes, the sea anemone receptor gene yields transcripts which can be alternatively spliced, thereby yielding a shortened receptor variant only containing the large extracellular (soluble) N terminus. All this is strong evidence that the putative glycoprotein hormone receptor from sea anemones is evolutionarily related to those from mammals. This is the first report showing that a putative glycoprotein hormone receptor occurs in invertebrates.

Neuropeptides are synthesized as large precursor proteins that undergo posttranslational cleavages and modifications to produce bioactive peptides. Here, we have cloned two closely related precursor proteins for the sea anemone neuropeptide Antho-RFamide (

Very little was known about the feeding habits of the actinian Calliactis parasitica, which almost exclusively lives on gastropod shells inhabited by anomuran crabs. Observations of behaviour in the field and the coelenteron contents of animals coming from two different ecological zones (infralittoral and circalittoral) in Thermaikos Gulf (North Aegean Sea) showed that C. parasitica is a non-selective omnivorous species which plays an important role in the benthic food web and its diet reflects the faunal composition in these two zones. Basically, this species is a suspension-feeder, although it can also remove food from the sediment by tactile tentacle motion. Complementary, occasional food sources are the remains of the prey of the associated anomurans.

We have isolated and sequenced the neuropeptide L-3-phenyllactyl-Phe-Lys-Ala-NH2 from the sea anemone Anthopleura elegantissima. This neuropeptide (named Antho-KAamide) has the unusual N-terminal L-3-phenyllactyl blocking group which has recently also been discovered in 2 other neuropeptides from sea anemones. We propose that the L-3-phenyllactyl residue renders Antho-KAamide resistant to nonspecific aminopeptidases, thereby increasing the stability of the neuropeptide after neuronal release. The existence of the L-3-phenyllactyl residue in 3 neuropeptides isolated so far suggests that this blocking group is more generally occurring.

Neuropeptides containing the carboxylterminal sequence Arg-Phe-NH2 are found throughout the animal kingdom and are important substances mediating neuronal communication. Here, we have cloned the cDNA coding for the precursor protein of the sea anemone neuropeptide (Antho-RFamide) less than Glu-Gly-Arg-Phe-NH2. This precursor is 334 amino acids in length and contains 19 copies of unprocessed Antho-RFamide (Gln-Gly-Arg-Phe-Gly), which are tandemly arranged in the C-terminal part of the protein. Paired basic residues (Lys-Arg) or single basic residues (Arg) occur at the C-terminal side of each Antho-RFamide sequence. These are likely signals for posttranslational cleavage. The processing signals at the N-terminal side of each Antho-RFamide sequence, however, include acidic residues. Processing at these amino acids must involve either an amino- or an endopeptidase that cleaves C-terminally of aspartic acid or glutamic acid residues. Such processing is, to our knowledge, hitherto unknown for peptidergic neurons. The Antho-RFamide precursor also contains two copies of the putative Antho-RFamide-related peptide Phe-Gln-Gly-Arg-Phe-NH2 and one copy of Tyr-Val-Pro-Gly-Arg-Tyr-NH2. In addition, the precursor protein harbors four other putative neuropeptides that are much less related to Antho-RFamide. This report shows that the biosynthetic machinery for neuropeptides in coelenterates, the lowest animal group having a nervous system, is already very efficient and similar to that of higher invertebrates, such as mollusks and insects, and vertebrates.

Using a radioimmunoassay for the carboxyl-terminal sequence Arg-Asn-NH2, we have purified a peptide from acetic acid extracts of the sea anemone Anthopleura elegantissima. By classical amino acid analyses, mass spectrometry, and 1H NMR spectroscopy, the structure of this peptide was determined as 3-phenyllactyl-Leu-Arg-Asn-NH2. By using reversed-phase HPLC and a chiral mobile phase, it was shown that the 3-phenyllactyl group had the L configuration. Immunocytochemical staining with antiserum against Arg-Asn-NH2 showed that L-3-phenyllactyl-Leu-Arg-Asn-NH2 (Antho-RNamide) was localized in neurons of sea anemones. The L-3-phenyllactyl group has not been found earlier in neuropeptides of vertebrates or higher invertebrates. We propose that this residue renders Antho-RNamide resistant to nonspecific aminopeptidases, thereby increasing the stability of the peptide after neuronal release.

Using a radioimmunoassay for the peptide sequence Arg-Phe-NH2 (RFamide), a novel peptide has been purified from acetic acid extracts of the sea anemone Anthopleura elegantissima. This peptide has the structure less than Glu-Gly-Leu-Arg-Trp-NH2, and was named Antho-RWamide II. Antho-RWamide II is a neuropeptide. Its structure is closely related to an earlier characterized neuropeptide from Anthopleura less than Glu-Ser-Leu-Arg-Trp-NH2 (Antho-RWamide I).