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At least 19 recordsLinked to original sources
PubMed1990

Nucleotide sequence of the histone H3-encoding gene from the scleractinian coral Acropora formosa (Cnidaria: Scleractinia).

The histone H3-encoding gene from the staghorn coral Acropora formosa has the 3'-hairpin structure which functions as termination/processing signal in nonpolyadenylated histone mRNAs. The predicted amino acid sequence is highly homologous with the major H3 histones of higher metazoans, and has least homology with the corresponding protist and fungal proteins. These data are inconsistent with the phylogenetic position which has been assigned to the Cnidaria by partial 18S rRNA sequence comparison.

Amino Acid Sequence↗
PubMed1990

Molecular and developmental biology of the Cnidaria--basic aspects and phylogenetic implications.

Cnidarians are generally considered to be the most primitive group of eumetazoans. They are therefore of considerable interest for comparative studies of metazoan development and evolution. The application of molecular techniques to cnidarians can provide important insights into developmental processes and phylogenetic relationships both within the phylum Cnidaria and among the eumetazoa. This paper reviews current knowledge of molecular and developmental biology of cinidarians with particular emphasis on tropical scleractinian corals and soft corals from the Great Barrier Reef region. Nucleotide sequencing of the histone gene cluster has unequivocally established that cnidarians are typical eumetazoans. Repeated sequence analysis has been applied to the staghorn corals, and implies a major divergence within this group, which corresponds with differences in sperm ultrastructure. Recent developmental studies of corals have indicated that some species have an unusual method of germ layer formation. Molecular events associated with this process, and with other important developmental stages, are currently under investigation. Other areas of current research interest, including targets for PCR-based investigations into cnidarian phylogeny, are highlighted.

Animals↗
PubMed1991

An extract from Hydra vulgaris (Cnidaria) nematocysts increases cytoplasmic Ca2+ levels in fibroblasts.

It was previously shown that a toxic protein present in an extract prepared from nematocysts of Hydra vulgaris (Cnidaria) is highly hemolytic and induces spasms in test animals (Klug et al., 1989, Toxicon 27, 325). We now demonstrate that this nematocyst extract affects cell viability and induces an increase of cytosolic Ca2+ concentration as measured in fura-2 loaded single fibroblasts. This increase is caused by Ca2+ entering from the external medium and the effect appears to be due to the hemolytic component of the venom.

Animals↗
PubMed1992

Characterization of heterotrimeric collagen molecules in a sea-pen (Cnidaria, Octocorallia).

The collagen of a primitive invertebrate, the sea-pen Veretillum Cnidaria, Octocorallia), was studied with respect to its molecular-chain composition. The soft extracellular tissues (mesoglea) were solubilized by limited pepsin proteolysis and the collagen was isolated by selective precipitation at 0.7 M NaCl under acidic conditions. The pepsinized molecules were 260 nm in length, as demonstrated by electron microscope studies of rotary-shadowed molecules and of the segment-long-spacing crystallites obtained by dialysis against ATP. SDS/PAGE of the extract produced two main bands susceptible to bacterial collagenase, designated as the alpha 1 and alpha 2 chain, which were differentiated clearly by their CNBr cleavage products and the higher glycosylation rate of the alpha 2 chain. The latter finding corresponds with the high hydroxylysine content of the alpha 2 chain. The alpha 1/alpha 2 chain ratio observed in SDS/PAGE and the fact that only one peak was obtained by concanavalin-A affinity chromatography of a non-denatured 0.7 M NaCl extract demonstrate the alpha 1 [alpha 2]2 molecular structure of this collagen. These results contrast with data on the structure of other coelenterates (i.e. [alpha]3 for sea anemone collagen molecules and alpha 1 alpha 2 alpha 3 for jellyfish collagen molecules). They are discussed in relation to the evolution of collagen.

Amino Acids↗
PubMed1978

Calcification of the collagenous axial skeleton of Veretillum cynomorium pall. (Cnidaria: Pennatulacea).

The axial skeletal rod of Veretillium cynomorium consists of a fibrillar collagenous matrix calcified with calcite. The present paper describes ultrastructural and crystallographic details of its organization and deposition. At the inferior end of the rod is a calcification gradient between the noncalcified tip and the rest of the axis. Initial mineral deposits, which are sometimes associated with cell debris, give rise to calcitic nodules which enlarge by the radical growth of several lobes. These nodules fuse and form the core of the axis. Subsequent increase in diameter of the rod involves the radial development of irregular columns of calcite which arise from the peripheral nodules. Mineral surfaces exhibit a distinctive microarchitecture which can be related to the predominantly c-axis parallel growth of the calcite. Particular attention is paid to the relationship between mineral and matrix. The collagen fibrils, embedded in the calcite but never impregnated with it, are not responsible for the initial nucleation of mineral. The crystallographic orientation of the calcite also appears to be independent of these fibrils.

Animals↗
PubMed1978

Fine structure of the neuromuscular system of Polyorchis penicillatus (Hydromedusae, Cnidaria).

Polyorchis penicillatus exhibits outer, inner and endodermal nerve rings. The inner ring contains a number of giant axons with infolded plasma membranes and annular gap junctions. The existence of an innervation supplying the velar radial muscle strengthens the view that the steering mechanism is under nervous control. The basal portions of the cells of the endoderm canals form a muscle band which might enable the animal to regulate the flow of materials or could perform peristalsis.

Animals↗
PubMed1992

Class-level relationships in the phylum Cnidaria: evidence from mitochondrial genome structure.

The phylogenetic relationships of the Recent cnidarian classes remain one of the classic problems in invertebrate zoology. We survey the structure of the mitochondrial genome in representatives of the four extant cnidarian classes and in the phylum Ctenophora. We find that all anthozoan species tested possess mtDNA in the form of circular molecules, whereas all scyphozoan, cubozoan, and hydrozoan species tested display mtDNA in the form of linear molecules. Because ctenophore and all other known metazoan mtDNA is circular, the shared occurrence of linear mtDNA in three of the four cnidarian classes suggests a basal position for the Anthozoa within the phylum.

Animals↗
PubMed1991

Emerging fractal properties in gorgonian growth forms (Cnidaria: Octocorallia).

Gorgonian growth has been hitherto studied mostly by investigating the influence of different environmental conditions on shape and orientation. We have made an attempt at analyzing the intrinsic growth properties of these organisms, by using a method capable of pointing out a fractal arrangement. Colony outlines of the gorgonian species Eunicella singularis, Eunicella cavolinii, Paramuricea clavata, and Lophogorgia ceratophyta have been digitized and their length measured by traveling along them with a series of logarithmically increasing steps. When this procedure is used on fractal lines, logarithmic plots of estimated length vs. step show linear trends, whose slope yields the fractal dimension. In gorgonian outlines, due to their limited multi-scale organization, we have found curved trends typical of non-fractal lines. However, non-linear regression analysis has shown that the degree of bending is variable from curve to curve, with differences among species. also, in P. clavata and L. ceratophyta there is a positive correlation between the degree of development and the tendency to assume a fractal geometry. This suggests that gorgonian growth mechanisms retain a self-similar design, which becomes evident only in species combining a large size with a high branch density. Based on these data, possibilities of modeling biological patterns through fractal growth models are questioned.

Animals↗
PubMed1979

[Genesis of connective matrix of Veretillum cynomorium Pall. (Cnidaria-Anthozoa). Ultrastructural and autoradiographic study (author's transl)].

Ultrastructural study of the tissues of Veretillum cynomorium shows the presence of two mesenchymatous cellular states in the mesoglea: the nongranular mesenchymatous cells and the granular mesenchymatous cells. These latter possess, besides their cytoplasmic granules, some homogeneous fibrous inclusions, very similar to the fibrous material of the mesoglea. Granules and homogeneous fibrous inclusions are also present in the cytoplasm of some ectodermic and endodermic cells. These morphological results lead us to consider that mesoglea and epithelia can be occupied by the same granular cell type. Besides this, the digestive endodermic cells are sometimes very rich in heterogeneous fibrous inclusions histochemically identified as phagosomes. An autoradiographic study indicates two possible pathways for the synthesis of the mesoglea. The first involves the endoderm which elaborates the mesoglea at a fast rate but in small amounts. The second is due to the granular cells (mesenchymatous and epithelial) which show a slow rate of synthesis leading to the formation of the homogeneous fibrous inclusions. The heterogeneous fibrous inclusions of the digestive endodermic cell support the hypothesis of the involvement of these cells in mesogleal degradation.

Animals↗
PubMed2026

Research on the ecology of the carnivorous sponge-associated iridovirus (CaSpA-IV) reveals its presence in the Cnidaria.

UNLABELLED: Carnivorous sponge-associated iridovirus (CaSpA-IV) is a recently described virus identified in two deep-sea cladorhizid sponge species from the Gulf of Maine and Baffin Bay. To assess its ecological distribution and potential transmission pathways, we molecularly screened for CaSpA-IV in 32 calanoid copepod samples collected across Newfoundland and Labrador coastal and shelf waters, along with 24 mucus swab and tissue samples collected from six individual deep-sea Paragorgia arborea coral colonies, and three seawater samples from the Gulf of Maine. Two P. arborea tissue specimens from different colonies were sequence-confirmed as CaSpA-IV-positive, making this the first detection of an iridovirus in this host. All copepod and seawater samples tested negative. However, calanoid copepods cannot be definitively ruled out as a transmission vector due to limited sampling. These findings demonstrate that CaSpA-IV may infect two invertebrate phyla in geographically distant benthic habitats. Future work should focus on whole-genome sequencing of diverse CaSpA-IVs and targeted sampling of other potential vectors/hosts to elucidate transmission routes and the ecological impact of this virus. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at https://doi.org/10.1007/s44370-026-00057-w.

Cladorhizidae↗
PubMed1990

Poly(gamma-glutamic acid)s are the major constituents of nematocysts in Hydra (Hydrozoa, Cnidaria).

The 2.80 +/- 0.20 mumol of anions found/mg of isolated and purified dry nematocysts (capsular secretory products of stinging cells) from Hydra make up the majority of the soluble capsular content. They are, in cooperation with corresponding cations, responsible for the generation and regulation of an internal osmotic pressure that amounts up to 150 bar (Weber, J. (1989) Eur. J. Biochem. 184, 465-476). The anions are organized as linear homopolymers of L-glutamic acids which are linked by gamma-carboxyl-alpha-amino amide bonds; the degree of polymerization is heterogeneous and dependent on the particular type of nematocyst. In situ the intracapsular glutamic acid monomer concentration is as high as 2 M. This is the first time that poly(gamma-glutamic acid)s, which are known to occur in some selected bacteria, are reported for eucaryotes. It is suggested that they may also be present as predominant components in nematocysts of other cnidarian species and thus might represent a class of compounds which is characteristic for a whole phylum of the animal kingdom.

Amino Acids↗
PubMed1976

The form and function of cnidarian spirocysts. 1. Ultrastructure of the capsule exterior and relationship to the tentacle sensory surface.

The commonest intracellular organelle characteristic of the Phylum Cnidaria or Coelenterata (Subclass Zoantharia) is the spirocyst. Based on scanning and transmission electron microscopy of the tentacles of sea anemones and corals, it appears that the tip of the spirocyst is either exposed to the environment or covered by a thin plasma membrane and often has a pebbled or knobby appearance. Surrounding the spirocyst tip is a ring-like structure which seems to be formed by the junction of the enclosing cell (the spirocyte) and the tip of the spirocyst. The spirocyst thread is continuous with the capsule wall and emerges from within the apical ring during discharge. No ciliary structures appear to be associated with spirocysts. Instead, two different types of microvilli have been found: short microvilli on the spirocyte itself and long microvilli furnished by the cell or cells surrounding the spirocyte. The significance of these findings is discussed in relation to the reception of stimuli for spirocyst discharge.

Animals↗
PubMed1975

Spermatogenesis in Anthozoa: differentiation of the spermatid.

The fine structure of spermatids has been examined in Calliactis, Protanthea, Gonactinia and Parazoanthus (Cnidaria, Anthozoa). The sperm cells are relatively simple and lack distinct acrosomes. Their nuclei, spherical in the zoanthid, in the actinians are slendertipped cones. Condensation of the chromatin is interpreted in terms of progressive coiling of densely-stained filaments and the elimination of nucleoplasm. Nuclear elongation occurs in the absence of microtubules. A well-developed centriolar complex is attached to the nuclear envelope by fibres and in this area (that of a shallow fossa in actinian spern) the nuclear membranes seem to be thickened. The centrioles are surrounded by a mitochondrial collar, especially pronounced in Calliactis. In contact with the mitochondria and nucleus is a ring of lipid-containing vesicles 300-700 nm in diameter. A system of densely-staining vesicles 150-300 nm in size corresponds to the "pro-acrosomal vesicles" described for other coelenterates. They are scattered in the peripheral cytoplasm and are regarded as derivatives of the endoplasmic reticulum. Problems of organelle function and of differentiation during spermiogenesis are discussed.

Animals↗
PubMed1977

The ontogeny of swimming behavior in the scyphozoan, Aurelia aurita. II. The effects of ions and drugs.

1. The responses of Aurelia medusae to pharmacological agents and ionic variation were classified into four response types: Type I, no response; Type II, inhibition of pacemaker activity; Type III, inhibition of both pacemakers and swimming muscles; and Type IV, increase in pacemaker output. 2. The swimming pacemakers of Aurelia medusae become hyperactive in Mg+2-free solutions (Type IV). This response appears to be general in swimming scyphozoa. 3. The response pattern to pharmacologically-active compounds indicates that the coelenterate neuromuscular system is quite different than those in other phyla. In fact, the response spectrum is not consistent within the Cnidaria. 4. Similarly, the responses of adult medusae to ionic variation show no consistent pattern within various scyphomedusae. 5. Test solutions from each response type established with medusae were selected and tested on the scyphistoma and strobila stages. The comparison of the responses to the test solutions between the medusa, scyphistoma, and strobila showed that the neuromuscular systems are physiologically different. The strobila, specificially the ephyra, is a mixture of both polypoid and medusoid response types. The strobila, therefore, is physiologically an intermediate stage in the development of the adult medusa.

Animals↗
PubMed1992

The presence and distribution of Antho-RFamide-like material in scyphomedusae.

The nervous systems of the scyphomedusae Chrysaora hysoscella, Cyanea capillata and Cyanea lamarckii (Phylum Cnidaria) were stained using an anti-serum against the anthozoan neuropeptide Antho-RFamide. Staining was widespread in all three species. In Chrysaora, the antiserum revealed nerve nets in the subumbrella and exumbrella ectoderm, in both faces of the oral lobes, and in the endoderm lining the subumbrella and exumbrella surfaces of the gastric cavity. The most prominent staining occurred in a dense plexus of neurons in the ectoderm at the base of the tentacles. This nerve net sent projections into the subumbrella ectoderm. For the most part, staining in the two species of Cyanea was similar to that in Chrysaora, with a few exceptions. These include the presence, in Cyanea, of an obvious tentacular nerve tract and nerve nets associated with clusters of cnidocytes in the tentacles. Radioimmunoassays of extracts from Chrysaora and Cyanea lamarkii revealed that both species contain large amounts of Antho-RFamide-like material (up to 55 nmol/animal). The results indicate that Antho-RFamide-like neuropeptides are widespread in scyphomedusae.

Animals↗