Parazoanthus Axinellae Research Articles

2bRAD reveals fine-scale genetic structuring among populations within the Mediterranean zoanthid Parazoanthus axinellae (Schmidt, 1862)

The zoanthid Parazoanthus axinellae (Schmidt, 1862) is a widespread coral species in the Mediterranean coralligenous assemblages where two morphotypes are found: Slender and Stocky, differing in size, color, and preferred substrate. Due to these marked differences, Slender and Stocky morphotypes were hypothesized to be two species. Here, we used 2bRAD to obtain genome‐wide genotyped single nucleotide polymorphisms (SNPs) to investigate the genetic differentiation between Slender and Stocky morphs, as well as their population structure. A total of 101 specimens of P. axinellae were sampled and genotyped from eight locations along the Italian coastline. In four locations, samples of the two morphotypes were collected in sympatry. 2bRAD genome-wide SNPs were used to assess the genetic divergence between the two morphotypes (1319 SNPs), and population connectivity patterns within Slender (1926 SNPs) and Stocky (1871 SNPs) morphotypes. Marked and consistent differentiation was detected between Slender and Stocky morphotypes. The widely distributed Slender morphotype showed higher population mixing patterns, while populations of the Stocky morphotype exhibited a stronger genetic structure at a regional scale. The strong genetic differentiation observed between P. axinellae Slender and Stocky morphotypes provides additional evidence that these morphs could be attributed to different species, although further morphological and ecological studies are required to validate this hypothesis. Our study highlights the importance of resolving phylogenetic and taxonomic disparities within taxonomically problematic groups, such as the P. axinellae species complex, when performing genetic connectivity studies for management and conservation purposes.Graphical Schematic overview of the main genetic structuring patterns observed in this study. Coral polyps were colored to intuitively associate the reader to Parazoanthus axinellae morphotypes, with orange tones being attributed to the Stocky morphotype, and yellow tones to the Slender morphotype. Bidirectional arrows represent gene flow between coral individuals, with the number and thickness of arrows corresponding to the intensity of gene flow rates. The red dashed line represents the potential reproductive isolation between Slender and Stocky morphs

The Mediterranean Zoanthid Parazoanthus axinellae as a Novel Source of Antimicrobial Compounds

Marine bioprospecting is a dynamic research field that explores the oceans and their biodiversity as noteworthy sources of new bioactive compounds. Anthozoans are marine animals belonging to the Cnidaria phylum characterized by highly specialized mechanosensory cells used both for defence against predators and prey capture. Here, high concentration of cnidocysts have been isolated from the Mediterranean zoanthid coral Parazoanthus axinellae (Schmidt, 1862) and their antimicrobial potential has been investigated. The cnidocyst extract exerted significant antibacterial activity against some human pathogens capable of developing resistance to conventional antibiotics such as Streptococcus agalactiae and Coccus sp., and against several Vibrio species, including some microbial strains for humans and farmed fish, such as Vibrio alginolyticus, Vibrio anguillarum, Vibrio fischeri, Vibrio harveyi, and Vibrio vulnificus. Results have been discussed in light of both the ecological aspects and biotechnological value of the cnidocyst extract in the nutritional, nutraceutical, and pharmaceutical fields.

Occurrence of phthalic acid esters (PAEs) and active pharmaceutical ingredients (APIs) in key species of anthozoans in Mediterranean Sea

The Mediterranean Sea's biodiversity is declining due to climate change and human activities, with plastics and emerging contaminants (ECs) posing significant threats. This study assessed phthalic acid esters (PAEs) and active pharmaceutical ingredients (APIs) occurrence in four anthozoan species (Cladocora caespitosa, Eunicella cavolini, Madracis pharensis, Parazoanthus axinellae) using solid phase microextraction (SPME) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). All specimens were contaminated with at least one contaminant, reaching maximum values of 57.3 ng/g for the ∑PAEs and 64.2 ng/g (wet weight) for ∑APIs, with dibutyl phthalate and Ketoprofen being the most abundant. P. axinellae was the most contaminated species, indicating higher susceptibility to bioaccumulation, while the other three species showed two-fold lower concentrations. Moreover, the potential adverse effects of these contaminants on anthozoans have been discussed. Investigating the impact of PAEs and APIs on these species is crucial, given their key role in the Mediterranean benthic communities.

Identification of the hydantoin alkaloids parazoanthines as novel CXCR4 antagonists by computational and in vitro functional characterization

CXCR4 chemokine receptor represents an attractive pharmacological target due to its key role in cancer metastasis and inflammatory diseases. Starting from our previously-developed pharmacophoric model, we applied a combined computational and experimental approach that led to the identification of the hydantoin alkaloids parazoanthines, isolated from the Mediterranean Sea anemone Parazoanthus axinellae, as novel CXCR4 antagonists. Parazoanthine analogues were then synthesized to evaluate the contribution of functional groups to the overall activity. Within the panel of synthesized natural and non-natural parazoanthines, parazoanthine-B was identified as the most potent CXCR4 antagonist with an IC50 value of 9.3 nM, even though all the investigated compounds were able to antagonize in vitro the down-stream effects of CXC12, albeit with variable potency and efficacy. The results of our study strongly support this class of small molecules as potent CXCR4 antagonists in tumoral pathologies characterized by an overexpression of this receptor. Furthermore, their structure–activity relationships allowed the optimization of our pharmacophoric model, useful for large-scale in silico screening.

Evidence of genetic isolation between two Mediterranean morphotypes of Parazoanthus axinellae

Coralligenous assemblages are among the most species-rich and vulnerable habitats of the Mediterranean Sea. Nevertheless, data on connectivity patterns on species inhabiting these habitats, crucial to define management and protection priorities, are largely lacking. Moreover, unreliable species-level taxonomy can confound ecological studies and mislead management strategies. In the northwestern Mediterranean two Parazoanthus axinellae morphotypes differing in size, color and preferred substrate are found in sympatry. In this study, we used COI and ITS sequence polymorphism to assess (1) the genetic divergence between the two morphotypes, (2) their connectivity patterns and (3) their phylogenetic position within the Parazoanthidae. Specimens of P. axinellae were sampled in 11 locations along the northwestern Mediterranean; in 6 locations, samples of the two morphotypes were collected in sympatry. Small genetic diversity and structure were found within morphotypes, while marked and consistent differentiation was detected between them. Moreover, the less widespread morphotype appeared to be closer to Pacific species as P. juanfernandezii and P. elongatus. Our findings confirmed the limited knowledge on Parazoanthus species complex, and how this gap can have important implication for the conservation strategies of this widespread and valuable genus in the Mediterranean Sea.

Deep coralligenous outcrops of the Apulian continental shelf: Biodiversity and spatial variability of sediment-regulated assemblages

Structure and spatial variability of coralligenous assemblages of the Apulian continental shelf in the southern Adriatic Sea were investigated. The area consists of small coralligenous outcrops distributed between 30 and 100 m of depth on coarse detritic or muddy bottom. Photographic samples, obtained through a Remotely Operated Vehicle, were analyzed to evaluate the abundance of the main taxa or morphological groups of macroalgae and sessile invertebrates, and the deposited sediment. A multifactorial sampling design was used to compare assemblages at two depth ranges, the shallow outcrops (between 35 and 45 m) and the deep outcrops (between 60 and 70 m), and to determine the main scales of spatial variation. Assemblages were dominated by encrusting and erect sponges, encrusting and filamentous algae, scleractinians, encrusting and erect bryozoans and the Zoantharia Parazoanthus axinellae. Deep assemblages were characterized by lower alpha and beta diversity, and by the decrease or disappearance of sensitive organisms, such as coralline macroalgae, scleractinians and erect bryozoans, and by the dominance of encrusting sponges, P. axinellae and hydrozoans. Sedimentation was higher on deep outcrops and was suggested to be the main driver of differences between shallow and deep assemblages. The peculiar composition of assemblages found in the Apulian continental shelf provides evidence that these outcrops represent an uncommon coralligenous habitat.

Total Synthesis of the Marine Natural Product Parazoanthine F by Copper‐Mediated C–N Coupling

AbstractThe total synthesis of the marine natural product parazoanthine F from the sea anemone Parazoanthus axinellae is described. The key problem was the assembly of an N‐styrylhydantoin moiety. It was possible to cleanly hydroxylate the benzylic position of the corresponding phenethyl unit by treatment with cerium ammonium nitrate. However, elimination to the alkene proved to be surprisingly difficult. The breakthrough came after optimizing the CuI/N,N′‐dimethylethylenediamine‐mediated C–N coupling of a 2,2,4,6,7‐pentamethyl‐5‐sulfonyl‐dihydrobenzofuran‐protected arginine amide with p‐methoxystyryl bromide under microwave conditions (70 °C, 200 W) in the presence of Cs2CO3. Our studies culminated in a short approach with an overall yield of about 12 %.

Amphipod community associated with invertebrate hosts in a Mediterranean marine cave

The present study explored the amphipod communities associated with the dominant host invertebrates inhabiting a marine cave of South Spain in order to describe their species composition and distribution patterns. Although they play a key role in the structure of mobile epifaunal communities inhabiting most rocky reef ecosystems, this component of marine caves communities has often been overlooked. Colonies of six sessile species were collected: Astroides calycularis, Parazoanthus axinellae, Pentapora fascialis, Aldeonella calveti, Filograna implexa, and Ircinia fasciculata. In each sample the mobile epifaunal community (mainly focusing on the amphipod group) was characterized, with Arthropoda and Amphipoda being the dominant phylum and order, respectively. Among amphipods, the gammarid Lembos websteri and the caprellids Phtisica marina and Pseudoprotella phasma were the most abundant species. The endangered coral Astroides calycularis showed the most distinctive amphipod community and multivariate analysis highlighted the existence of significant differences in the amphipod assemblages among invertebrate hosts in the cave. However, no host-specific species were found. Benthic hosts inside the cave are mainly used as a refuge by amphipods and all the sessile species studied seem to play an equivalent facilitation role. To what extent changes in the composition of sessile species may affect other associated species was also discussed.

Metabolomic profiling reveals deep chemical divergence between two morphotypes of the zoanthid Parazoanthus axinellae.

Metabolomics has recently proven its usefulness as complementary tool to traditional morphological and genetic analyses for the classification of marine invertebrates. Among the metabolite-rich cnidarian order Zoantharia, Parazoanthus is a polyphyletic genus whose systematics and phylogeny remain controversial. Within this genus, one of the most studied species, Parazoanthus axinellae is prominent in rocky shallow waters of the Mediterranean Sea and the NE Atlantic Ocean. Although different morphotypes can easily be distinguished, only one species is recognized to date. Here, a metabolomic profiling approach has been used to assess the chemical diversity of two main Mediterranean morphotypes, the “slender” and “stocky” forms of P. axinellae. Targeted profiling of their major secondary metabolites revealed a significant chemical divergence between the morphotypes. While zoanthoxanthin alkaloids and ecdysteroids are abundant in both morphs, the “slender” morphotype is characterized by the presence of additional and bioactive 3,5-disubstituted hydantoin derivatives named parazoanthines. The absence of these specific compounds in the “stocky” morphotype was confirmed by spatial and temporal monitoring over an annual cycle. Moreover, specimens of the “slender” morphotype are also the only ones found as epibionts of several sponge species, particularly Cymbaxinella damicornis thus suggesting a putative ecological link.

Metabolic profiling reveals deep chemical divergence between two morphotypes of the zoanthid Parazoanthus axinellae

Metabolomic approaches have recently proven their usefulness to discriminate between cryptic species and to assist in the classification of marine invertebrates. Among the metabolite-rich cnidarian order Zoantharia, Parazoanthus is a polyphyletic genus whose systematics and phylogeny remain controversial. Within this genus, one of the best known species, Parazoanthus axinellae is prominent in rocky shallow waters of the Mediterranean Sea and the NE Atlantic Ocean. Although different morphotypes can easily be distinguished, only one species is recognized to date. Here, a metabolic profiling approach has been used to assess the chemical diversity of two main Mediterranean morphotypes, the “slender” and “stocky” forms of P. axinellae. Targeted profiling of major secondary metabolites revealed a significant chemical divergence between both morphotypes. While zoanthoxanthin alkaloids and ecdysteroids are abundant in both morphs, the “slender” morphotype is characterized by the presence of additional and unique parazoanthine alkaloids. The absence of parazoanthines in the “stocky” morphotype was confirmed by spatial and temporal series monitoring over one year cycle. Parazoanthines were found to be responsible for the ecological bioactivity of the extracts of this morph. Additionally, specimens of the “slender” morphotype are also the only ones found as epibionts of several sponge species, particularly Cymbaxinella damicornis.

Metabolome consistency: additional parazoanthines from the mediterranean zoanthid parazoanthus axinellae.

Ultra-high pressure liquid chromatography coupled to high resolution mass spectrometry (UHPLC-MS/MS) analysis of the organic extract obtained from the Mediterranean zoanthid Parazoanthus axinellae yielded to the identification of five new parazoanthines F-J. The structures were fully determined by comparison of fragmentation patterns with those of previously isolated parazoathines and MS/MS spectra simulation of in silico predicted compounds according to the metabolome consistency. The absolute configuration of the new compounds has been assigned using on-line electronic circular dichroism (UHPLC-ECD). We thus demonstrated the potential of highly sensitive hyphenated techniques to characterize the structures of a whole family of natural products within the metabolome of a marine species. Minor compounds can be characterized using these techniques thus avoiding long isolation processes that may alter the structure of the natural products. These results are also of interest to identify putative bioactive compounds present at low concentration in a complex mixture.

Reproductive biology of Parazoanthus axinellae (Schmidt, 1862) and Savalia savaglia (Bertoloni, 1819) (Cnidaria, Zoantharia) from the NW Mediterranean coast

Despite the wide distribution of zoanthids, little is known about their pattern of reproduction. Here we investigate the reproductive biology of two Mediterranean species, the common Parazoanthus axinellae (Schmidt) and the rare Savalia savaglia (Bertoloni). For both species, samples were collected during an annual cycle, from January to December 2005, in the Western Mediterranean (Ligurian Sea, Italy). Both species are gonochoric. In P. axinellae the sex-ratio (n colonies = 30) showed a slight predominance of male colonies (M/F = 1.35), whereas in the population of S. savaglia (n colonies = 15) a predominance of females was found (M/F = 0.3). In P. axinellae the first gametocytes were visible in March, whereas in S. savaglia they became visible in May. Both species reproduce at the end of autumn when seawater temperature begins to decrease. Parazoanthus axinellae (10 m depth) spawns eggs and sperms in November, whereas S. savaglia (67 m depth) spawns in December. In P. axinellae sexes were segregated on a rocky wall, with males occurring deeper, whereas male and female colonies of S. savaglia were irregularly dispersed in the population. The maximum number of oocytes differed between the species, being higher in P. axinellae than in S. savaglia.

Colonization of an artificial reef in south-west England—ex-HMS ‘Scylla’

An ex-Royal Navy frigate, HMS ‘Scylla’, was placed on the seabed in Whitsand Bay, south Cornwall on 27 March 2004. After five years, the reef supported a mature steel wreck community. The colonization of the reef showed wide fluctuations in species abundance in the first two years but, by 2006, most species that dominated or characterized the reef after five years had settled. Significant colonization events included settlement of barnacles, tubeworms and hydroids within a month and remarkably high settlements of the sea urchin Psammechinus miliaris and the queen scallop Aequipecten opercularis in the first year together with starfish Asterias rubens, solitary sea squirts and ephemeral algae. The plumose anemone Metridium senile, a characteristic species of wrecks, arrived in late summer 2004 but the widely distributed dead man's fingers Alcyonium digitatum was not observed until spring 2005. Wrasse were slow to colonize the reef but were established in small numbers by the end of 2007. Sea fans, Eunicella verrucosa, were first observed in August 2007. The species count for the reef stood at 263 taxa by the end of March 2009. The inside of the reef remained poorly colonized even after five years. Areas coated with tributyltin (TBT) antifouling paint only had colonization where the paint had flaked-off or on non-toxic paint markings, but with some indication that colonization may be occurring by a very few species especially near to non-TBT areas. Many species characteristic of natural reefs had not settled and neither do they occur on older wrecks including branching axinellid sponges, some cushion sponges and the yellow cluster anemone Parazoanthus axinellae. The artificial reef developed a community that was distinctly different to nearby natural rock reefs and such artificial structures should not be considered as a replacement for damaged or destroyed natural habitats.

Parazoanthines A−E, Hydantoin Alkaloids from the Mediterranean Sea Anemone Parazoanthus axinellae

Five new hydantoin alkaloids, named parazoanthines A-E (1-5), were isolated as the major constituents of the Mediterranean sea anemone Parazoanthus axinellae. Their structural elucidation was achieved through NMR spectroscopic and mass spectrometric analyses. The absolute configuration of the chiral compounds 1 and 4 was determined by comparison between experimental and TDDFT-calculated CD spectra. The configuration of the trisubstituted double bond of 2, 3, and 5 was deduced from the (3)J(H6-C4) coupling constant value. This family of alkaloids represents the first example of natural 3,5-disubstituted hydantoins that do not exhibit a methyl at N-3. All compounds were tested for their natural toxicity (Microtox assay), and parazoanthine C (3) exhibited the highest natural toxicity.

Summer disease in Parazoanthus axinellae (Schmidt, 1862) (Cnidaria, Zoanthidea)

Climate change is affecting marine environments all over the world but scientists' attention is mainly devoted to tropical areas. In the Mediterranean Sea, species with a cold affinity are decreasing very fast from 0 to 40 m depth, while warm water species increase. From 2000, several populations of the zoanthid Parazoanthus axinellae (Schmidt 1882) have been showing signs of suffering along the Ligurian coast. Here we report a three‐year monitoring, from June 2001 to September 2003, of a population of P. axinellae on the rocky cliff of the Portofino Promontory (Ligurian Sea). During this span of time the population, which covered an area of several square metres with a density of about 1 polyp cm−2, was severely reduced. In the meanwhile an encrusting sponge, Crambe crambe, rapidly colonized the free substrates abandoned by the zoanthid. Warm water and the massive proliferation of a cyanobacterium attributed to the genus Porphyrosiphon are hypothesized to be the main causes of this disease.

Life-history traits of Alcyonium acaule and Parazoanthus axinellae (Cnidaria, Anthozoa), with emphasis on growth

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 178:193-204 (1999) - doi:10.3354/meps178193 Life-history traits of Alcyonium acaule and Parazoanthus axinellae (Cnidaria, Anthozoa), with emphasis on growth Joaquim Garrabou* Departament d'Ecologia, Universitat de Barcelona, Avgda. Diagonal 645, E-08028 Barcelona, Spain *Present address: Station Marine d'Endoume, CNRS-UM 6540 DIMAR, rue Batterie des Lions, F-13007 Marseille, France. E-mail: garrabou@porthos.bio.ub.es ABSTRACT: Life-history aspects of 2 common cnidarians, Parazoanthus axinellae and Alcyonium acaule, were studied in the northwestern Mediterranean over 2 yr. Rates of growth (i.e. area gained) and shrinkage (i.e. area lost), colony fission and fusion, mortality, feeding activity and preliminary data on recruitment (for A. acaule) were measured. Independent growth and shrinkage rates of P. axinellae were measured as area gained and lost per month respectively using a photographic and computer-assisted image analysis. Measurement of growth in A. acaule was based on size variations of the colonies over 2 yr. Results indicated moderate growth dynamics for P. axinellae and very slow growth by A. acaule. Growth rates and shrinkage rates in P. axinellae showed non-significant differences over time, although growth rates peaked during summer to autumn periods for both monitored years. In general, growth dynamics for the cnidarians studied were similar to or lower than those reported for related species from temperate and tropical habitats. Fission events were common in P. axinellae. Of the colonies monitored, 29% underwent at least 1 fission event in 2 yr. Fusion events occurred less frequently; only 8% underwent 1 fusion event. Neither fusion nor fission occurred in A. acaule. Mortality rates were about 10 % yr-1 for both species. Preliminary data showed low recruitment rates for A. acaule. Data on life-history traits were interpreted as evidence for distinct biological strategies used to persist and to occupy new substrata. P. axinellae based its strategy on a greater dynamic spreading over the substrata at moderate rates, by somatic growth and by fission. In contrast, A. acaule showed relatively slow growth but greater longevity. KEY WORDS: Mediterranean · Clonal organisms · Cnidaria · Alcyonacea · Zoanthidea · Life-history · Growth rate · Shrinkage rate Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 178. Publication date: March 17, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

Acetylcholinesterase inhibition in CNS and in peripheral nerves by pax isolated from the coral parazoanthus axinellae

Acetylcholinesterase inhibition in CNS and in peripheral nerves by pax isolated from the coral parazoanthus axinellae

Reproduction in Zoanthidea (Anthozoa: Hexacorallia)

Summary The state of knowledge concerning the reproductive biology of zoanthids is reviewed. Colonies in the suborder Macrocnemina, with few exceptions, are gonochoric; those in Brachycnemina are probably basically hermaphroditic but accurate sampling in colonies that fragment is difficult and exceptions by species or populations occur. Two deepsea species of Epizoanthus breed continuously but temperate shallow water zoanthids, and those in the tropics outside ∼15° latitude are iteroparous with spawning in summer or when temperatures are rising. Oogenesis occurs over a few months but the spawning event may be very brief. Parazoanthus parasiticusin Bermuda spawns mainly on 1–2 nights in late August or September, apparently at full moon;Protopalythoa sp. 1, and probably Palythoa caesia in the Great Barrier Reef spawn 3–5 nights after full moon in November (early summer). These species with short, precisely defined spawning seasons may undergo a second, smaller-scale spawning event one month after the first. Some intertidal populations seem rarely to reproduce sexually, and there have been no studies on the annual cycles of zoanthids in near equatorial waters. With few exceptions gametogenesis occurs only in non-directive macrosepta; in hermaphroditic colonies oocytes and sperm cysts may be intermingled on the same septa or be separate. Germ cells in Isozoanthus giganteus originate only from the endocoelic face of the septa, but this has not been confirmed in other species. Nutritive structures (trophonemata) are present both in oocytes and sperm cysts, in the latter functioning also for the egress of sperm. Trophonemata may be conspicuous, as in Par-parasiticus, or poorly developed, as in Protopalythoa sp. 1. Live eggs vary from −300 µm (most zoanthids) to ∼500 µm diameter in Palythoa spp.; in the two mass spawning species from the Great Barrier Reef they are shed as compact ovoid egg (or egg/sperm) bundles. Fecundity in zoanthids, from few studies, is variable and dependent on polyp size; estimates of 100–300×103 ova 100 cm−2 of colony have been made for Caribbean reef species. Internal brooding is known definitely only in Isozoanthus giganteus. Amongst zooxanthellate zoanthids, only Protopalythoa sp. 1 is known to transmit zooxanthellae via its oocytes. Several zoanthids are known to produce palytoxin but it is unclear to what extent the toxin accumulates in the ova. Larval development is summarized. Zoanthella-larvae are known to be produced in Palythoa, Protopalythoa and Sphenopus, and zoanthina-larvae in Isaurus and Zoanthus, all Brachycnemina. Larval type in Epizoanthus and Parazoanthus, both Macrocnemina, is unknown. Early metamorphosis of zoanthella and zoanthina larvae has been reported but not studied; older larvae, taken from the plankton, may have lost competency to settle. All zoanthids, except Sphenopus, form colonies, clones, or mixtures of the two, and propagate by budding. Attention is drawn to unusual methods of budding or cloning in Acrozoanthus, Isaurus, Palythoa, Sphenopus, and Parazoanthus axinellae. In reefal Isaurus, Protopalythoa, and Zoanthus actual colony size remains small due to fragmentation, but genet size may be substantial. Population structure depends on the interplay of recruitment, fragmentation, and local dispersal.

Sponge phylogeny, animal monophyly, and the origin of the nervous system: 18S rRNA evidence

We sequenced 18S rRNA genes of a calcareous sponge, Clathrina cerebrum, a demosponge, Axinella polypoides, and a zoanthid cnidarian, Parazoanthus axinellae. Our phylogenetic analysis supports the monophyly of kingdom Animalia and confirms that choanoflagellate protozoans are their closest relatives. Sponges as a whole are monophyletic, but possibly paraphyletic; demosponges and hexactinellids form a monophyletic group of silicious sponges. Our phylogenetic trees support a monophyletic origin of the nervous system in the immediate common ancestor of Cnidaria and Ctenophora. They weakly suggest that animals with a nervous system may be more closely related to calcareous sponges than to silicious sponges; the nervous system might have originated in an early calcareous sponge. Our trees confirm that Myxozoa and Placozoa are animals that arose by secondary loss of the nervous system, but suggest that Myxozoa may be sisters of, rather than derived from, Bilateria. Kingdom Animalia is divided into four subkingdoms: Radiata (Porifera, Cnidaria, Placozoa, Ctenophora), Myxozoa, Mesozoa, and Bilateria. The 18S rRNA genes of Myxozoa evolved over twice as fast as in Radiata. Comparison with the fossil record reveals a brief 10-fold (or greater) acceleration in the rate of rRNA evolution in early Bilateria followed by normal low rates for about 500 million years.

Nhibition of membrane-bound acetylcholinesterase by a new AChE inhibitor from the zoanthid Parazoanthus axinellae

nhibition of membrane-bound acetylcholinesterase by a new AChE inhibitor from the zoanthid Parazoanthus axinellae