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At least 73 records · Page 4Linked to original sources
PubMed2000

High level of genetic divergence between sympatric color morphs of the littoral sea anemone Anthopleura orientalis (Anthozoa: Actiniaria).

Using enzyme electrophoresis and nematocyst analysis, the sympatrically occurring "light" and "dark" color morphs of the sea anemone Anthopleura orientalis from the Sea of Japan were shown to be two valid species. The "light" morph was identified as A. orientalis (Averintsev, 1967 Issledovaniya fauny morei: Vyp. 5 (13). Nanka, Leningrad, pp. 62-77), while the "dark" morph was designated as Anthopleura sp. The analysis of 21 isozyme loci revealed high value of Nei's genetic distance (D=1.284) between the two species, which are indistinguishable in their external morphology. The mean values of observed and expected heterozygosities for A. orientalis and Anthopleura sp. are high (H(o)=0.252+/-0.061, H(e)=0.250+/-0.061 and H(o)=0.327+/-0.052, H(e)=0.351+/-0.054, respectively). The species differ significantly in the size of spirocysts and nematocysts, among which the atrichs from acrorhagi and the basitrichs from actinopharynx contribute most to the observed difference. Strong qualitative difference is revealed between distributions of nematocysts in mesenteric filaments of the two sea anemone species studied. The possible conspecificity of Anthopleura sp. with Anthopleura artemisia (Dana, 1848) is discussed and the conclusion made that these are two separate species.

Journal Article↗
PubMed1999

Fluorescent proteins from nonbioluminescent Anthozoa species.

We have cloned six fluorescent proteins homologous to the green fluorescent protein (GFP) from Aequorea victoria. Two of these have spectral characteristics dramatically different from GFP, emitting at yellow and red wavelengths. All the proteins were isolated from nonbioluminescent reef corals, demonstrating that GFP-like proteins are not always functionally linked to bioluminescence. The new proteins share the same beta-can fold first observed in GFP, and this provided a basis for the comparative analysis of structural features important for fluorescence. The usefulness of the new proteins for in vivo labeling was demonstrated by expressing them in mammalian cell culture and in mRNA microinjection assays in Xenopus embryos.

Amino Acid Sequence↗
PubMed2002

The genetic structure of the rare lagoonal sea anemone, Nematostella vectensis Stephenson (Cnidaria; Anthozoa) in the United Kingdom based on RAPD analysis.

The sea anemone Nematostella vectensis occurs in lagoons in the United States and along the southern and eastern coasts of the United Kingdom. In the United Kingdom it is considered rare and is threatened, principally through the destruction of lagoonal habitat. Random amplified polymorphic DNA (RAPD) data from populations across most of the rane of N. vectensis in the United Kingdom revealed that 61% of individuals had an identical genotype, the frequency of which varied from 0.01 to 1.00. These data provide strong evidence for predominantly clonal reproduction and for the existence of a 'general-purpose genotype' in the UK populations. Alternatively, the low levels of genetic variation observed in some N. vectensis populations may have resulted if they were founded from very few successful individuals from the United States. Analysis of molecular variance (amova) showed significant genetic differentiation between lagoons with no large-scale pattern of geographical variation. This result is consistent with occasional passive or anthropogenic dispersal of low numbers of individuals between lagoons followed by asexual proliferation of immigrants. Transplantation of individuals of the predominant (general-purpose) genotype, for conservation purposes, will probably stand a good chance of survival given its prevalence throughout the United Kingdom.

Analysis of Variance↗
PubMed2002

A far-red fluorescent protein with fast maturation and reduced oligomerization tendency from Entacmaea quadricolor (Anthozoa, Actinaria).

We performed the biochemical and biophysical characterization of a red fluorescent protein, eqFP611, from the sea anemone Entacmaea quadricolor cloned in Escherichia coli. With an excitation maximum at 559 nm and an emission maximum at 611 nm, the recombinant protein shows the most red-shifted emission and the largest Stokes shift of all nonmodified proteins in the green fluorescent protein family. The protein fluoresces with a high quantum yield of 0.45, although it resembles the nonfluorescent members of this protein class, as inferred from the absence of the key amino acid serine at position 143. Fluorescence is constant within the range pH 4-10. Red fluorophore maturation reaches a level of 90% after approximately 12 h by passing through a green intermediate. After complete maturation, only a small fraction of the green species (less than 1%) persists. The protein has a reduced tendency to oligomerize, as shown by its monomeric appearance in SDS/PAGE analysis and single-molecule experiments. However, it forms tetramers at higher concentrations in the absence of detergent. Fluorescence correlation spectroscopy reveals light-driven transitions between bright and dark states on submillisecond and millisecond time scales. Applicability of eqFP611 for in vivo labeling in eukaryotic systems was shown by expression in a mammalian cell culture.

Amino Acid Sequence↗
PubMed2000

Cracks in the beta-can: fluorescent proteins from Anemonia sulcata (Anthozoa, Actinaria).

We characterize two green fluorescent proteins (GFPs), an orange fluorescent protein, and a nonfluorescent red protein isolated from the sea anemone Anemonia sulcata. The orange fluorescent protein and the red protein seem to represent two different states of the same protein. Furthermore, we describe the cloning of a GFP and a nonfluorescent red protein. Both proteins are homologous to the GFP from Aequorea victoria. The red protein is significantly smaller than other GFP homologues, and the formation of a closed GFP-like beta-can is not possible. Nevertheless, the primary structure of the red protein carries all features necessary for orange fluorescence. We discuss a type of beta-can that could be formed in a multimerization process.

Amino Acid Sequence↗
PubMed2004

Investigating the origins of triploblasty: 'mesodermal' gene expression in a diploblastic animal, the sea anemone Nematostella vectensis (phylum, Cnidaria; class, Anthozoa).

Mesoderm played a crucial role in the radiation of the triploblastic Bilateria, permitting the evolution of larger and more complex body plans than in the diploblastic, non-bilaterian animals. The sea anemone Nematostella is a non-bilaterian animal, a member of the phylum Cnidaria. The phylum Cnidaria (sea anemones, corals, hydras and jellyfish) is the likely sister group of the triploblastic Bilateria. Cnidarians are generally regarded as diploblastic animals, possessing endoderm and ectoderm, but lacking mesoderm. To investigate the origin of triploblasty, we studied the developmental expression of seven genes from Nematostella whose bilaterian homologs are implicated in mesodermal specification and the differentiation of mesodermal cell types (twist, snailA, snailB, forkhead, mef2, a GATA transcription factor and a LIM transcription factor). Except for mef2, the expression of these genes is largely restricted to the endodermal layer, the gastrodermis. mef2 is restricted to the ectoderm. The temporal and spatial expression of these 'mesoderm' genes suggests that they may play a role in germ layer specification. Furthermore, the predominantly endodermal expression of these genes reinforces the hypothesis that the mesoderm and endoderm of triploblastic animals could be derived from the endoderm of a diploblastic ancestor. Alternatively, we consider the possibility that the diploblastic condition of cnidarians is a secondary simplification, derived from an ancestral condition of triploblasty.

Amino Acid Sequence↗
PubMed2001

Morphological characteristics by SEM observations and regulatory volume decrease (RVD) of tentacular nematocytes isolated by heat dissociation from Aiptasia diaphana (Cnidaria: Anthozoa).

This paper examines the morphological characteristics and response to hyposmotic shock of nematocytes isolated by heat dissociation at 45 degrees C for 20 min from the tentacles of Aiptasia diaphana, an anthozoan living in the brackish water of Lake Faro (Messina, Italy). Morphological characteristics were evaluated by scanning electron microscopy (SEM) observations and cytological test, functional characteristics by exposure to 35% hyposmotic stress. 81% of the population of isolated nematocytes had ciliary protrusions. Microbasic-mastigophore and amastigophore nematocytes had a hair bundle at the crown shaped apex composed of ciliary protrusions of different heights and diameters. In basitrichs, instead, a single ciliary protrusion was observed. Following exposure to 35% hyposmotic shock, nematocytes isolated by heat dissociation did not show RVD, while, following treatment with 1 microM and 2 microM gramicidin-S, activation of volume regulation in conditions of hyposmoticity was observed. The effect of gramicidin was concentration-dependent and confirmed the relevant role of conductance to K+ in volume regulation, as previously described (17) on nematocytes isolated by chemical methods.

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↗
PubMed2007

Mitochondrial genome of Savalia savaglia (Cnidaria, Hexacorallia) and early metazoan phylogeny.

Mitochondrial genomes have recently become widely used in animal phylogeny, mainly to infer the relationships between vertebrates and other bilaterians. However, only 11 of 723 complete mitochondrial genomes available in the public databases are of early metazoans, including cnidarians (Anthozoa, mainly Scleractinia) and sponges. Although some cnidarians (Medusozoa) are known to possess atypical linear mitochondrial DNA, the anthozoan mitochondrial genome is circular and its organization is similar to that of other metazoans. Because the phylogenetic relationships among Anthozoa as well as their relation to other early metazoans still need to be clarified, we tested whether sequencing the complete mitochondrial genome of Savalia savaglia, an anthozoan belonging to the order Zoantharia (=Zoanthidea), could be useful to infer such relationships. Compared to other anthozoans, S. savaglia's genome is unusually long (20,766 bp) due to the presence of several noncoding intergenic regions (3691 bp). The genome contains all 13 protein coding genes commonly found in metazoans, but like other Anthozoa it lacks most of the tRNAs. Phylogenetic analyses of S. savaglia mitochondrial sequences show Zoantharia branching closely to other Hexacorallia, either as a sister group to Actiniaria or as a sister group to Actiniaria and Scleractinia. The close relationships suggested between Zoantharia and Actiniaria are reinforced by strong similarities in their gene order and the presence of similar introns in the COI and ND5 genes. Our study suggests that mitochondrial genomes can be a source of potentially valuable information on the phylogeny of Hexacorallia and may provide new insights into the evolution of early metazoans.

Animals↗
PubMed2004

Cloning of anthozoan fluorescent protein genes.

Many cnidarians display vivid fluorescence under proper lighting conditions. In general, these colors are due to the presence of fluorescent proteins similar to the green fluorescent protein (GFP) originally isolated from the hydrozoan medusa Aequorea victoria (Cnidaria: Hydrozoa). To optimize the search for new fluorescent proteins (FPs), a technique was developed that allows for the rapid cloning and screening of FP genes without the need for a prior knowledge of gene sequence. Using this method, four new FP genes were cloned, a green from Montastraea cavernosa (Anthozoa: Scleractinia: Faviidae), a cyan from Pocillopora damicornis (Anthozoa: Scleractinia: Pocilloporidae), a cyan from Discosoma striata (Anthozoa: Corallimorpharia), and a red from a second Discosoma species. Two additional green FPs were cloned, one from M. cavernosa and one from its congener Montastraea faveolata, from purified cDNA using PCR primers designed for the first M. cavernosa green FP. Each FP has recognizable amino acid sequence motifs that place them conclusively in the GFP protein family. Mutation of these products using a low-stringency PCR protocol followed by screening of large numbers of bacterial colonies allowed rapid creation of mutants with a variety of characteristics, including changes in color, maturation time, and brightness. An enhanced version of the new red FP, DspR1+, matures faster at 30 degrees C than the commercially available DsRed but matures slower than DsRed at 37 degrees C. One of the M. cavernosa green FPs, McaG2, is highly resistant to photobleaching and has a fluorescence quantum yield approximately twice that of EGFP-1.

Amino Acid Sequence↗
PubMed1999

Isolation of Hox genes from the scyphozoan Cassiopeia xamachana: implications for the early evolution of Hox genes.

The isolation of Hox genes from two cnidarian groups, the Hydrozoa and Anthozoa, has sparked hypotheses on the early evolution of Hox genes and a conserved role for these genes for defining a main body axis in all metazoan animals. We have isolated the first five Hox genes, Scox-1 to Scox-5, from the third cnidarian class, the Scyphozoa. For all but one gene, we report full-length homeobox plus flanking sequences. Four of the five genes show close relationship to previously reported Cnox-1 genes from Hydrozoa and Anthozoa. One gene, Scox-2, is an unambiguous homologue of Cnox-2 genes known from Hydrozoa, Anthozoa, and also Placozoa. Based on sequence similarity and phylogenetic analyses of the homeobox and homeodomain sequences of known Hox genes from cnidarians, we suggest the presence of at least five distinct Hox gene families in this phylum, and conclude that the last common ancestor of the Recent cnidarian classes likely possessed a set of Hox genes representing three different families, the Cnox-1, Cnox-2, and Cnox-5 families. The data presented are consistent with the idea that multiple duplication events of genes have occurred within one family at the expense of conservation of the original set of genes, which represent the three ancestral Hox gene families.

Amino Acid Sequence↗
PubMed1995

Isolation and characterization of a mini-collagen gene encoding a nematocyst capsule protein from a reef-building coral, Acropora donei.

Genomic and cDNA clones of a mcol gene encoding mini-collagen (MCOL), a nematocyst capsule protein, have been isolated from a reef-building coral, Acropora donei (Anthozoa). The gene and its flanking regions, comprising 5382 bp and covering three exons and two introns, were sequenced. Exons 2 and 3 together have an open reading frame which can encode a MCOL of 176 amino acids (aa). The coral MCOL has all the characteristic regions present in the four hydra MCOL specified by the four mcol cDNA clones previously isolated from Hydra magnipapillata (Hydrozoa) by Kurz et al. [J. Cell Biol. 115 (1991) 1159-1169], including a central Gly-Xaa-Yaa region and flanking Pro-rich and Cys-repeat regions. This observation suggests that a mcol family is highly conserved in Anthozoa and Hydrozoa, and also that the characteristic regions present in MCOL are essential for the structure and function of these peptides.

Amino Acid Sequence↗
PubMed2001

Alternative cyclization in GFP-like proteins family. The formation and structure of the chromophore of a purple chromoprotein from Anemonia sulcata.

Anemonia sulcata purple protein (asFP595) belongs to a family of green fluorescent protein (GFP)-like proteins from the Anthozoa species. Similar to GFP, asFP595 apparently forms its chromophore by modifying amino acids within its polypeptide chain. Until now, the GFP-like proteins from Anthozoa were thought to contain chromophores with the same imidazolidinone core as GFP. Mass spectral analysis of a chromophore-containing tryptic pentapeptide from asFP595 demonstrates that chromophore formation in asFP595 is stoichiometrically the same as that in GFP: one H(2)O and two H(+) are released while a Schiff base and dehydrotyrosine are formed. However, structural studies of this asFP595 chromopeptide show that in contrast to GFP, the other peptide bond nitrogen and carbonyl carbon are required for chromophore cyclization, a reaction that yields the six-membered heterocycle 2-(4-hydroxybenzylidene)-6-hydroxy-2,5-dihydropyrazine. Spectrophotometric titration reveals three pH-dependent forms of the asFP595 chromopeptide: yellow (absorption maximum = 430 nm) at pH 3.0; red (absorption maximum = 535 nm) at pH 8.0; and colorless (absorption maximum = 380 nm) at pH 14.0. The pK(a) values for these spectral transitions (6.8 and 10.9) are consistent with the ionization of the phenolic group of dehydrotyrosine and deprotonation of the amidinium cation in the chromophore heterocycle, respectively. The amidinium group in asFP595 accounts for the unique absorption spectrum of the protein, which is substantially red-shifted relative to that of GFP. When the asFP595 chromophore cyclizes, the Cys-Met bond adjacent to the chromophore hydrolyzes, splitting the chromoprotein into 8- and 20-kDa fragments. High performance liquid chromatography analysis of a tryptic digest of denatured asFP595 shows that a pentapeptide with the cleaved Cys-Met bond is the only fragment associated with the red-shifted absorbance. These results imply that fragmentation of asFP595 is a critical step in protein maturation.

Animals↗
PubMed1985

Jellyfish mesogloea collagen. Characterization of molecules as alpha 1 alpha 2 alpha 3 heterotrimers.

The mesogloea collagen of a primitive animal, the jellyfish Stomolophus nomurai, belonging to the class Scyphozoa in the Coelenterata, was studied with respect to its chain structure. Most of the mesogloea collagen was solubilized by limited digestion with pepsin and isolated by selective precipitation at 0.9 m NaCl in 0.5 M acetic acid. Upon denaturation, the pepsin-solubilized collagen produced three distinct alpha chains, alpha 1, alpha 2, and alpha 3, in comparable amounts which were separable by CM-cellulose chromatography. The nonidentity of these alpha chains was confirmed by amino acid and carbohydrate analyses and peptide mapping. Furthermore, the introduction of intramolecular cross-links into native molecules by formaldehyde yielded a large proportion of gamma 123 chain with chain structure alpha 1 alpha 2 alpha 3, as judged by chromatographic behavior and peptide maps. We concluded that mesogloea collagen is comprised of alpha 1 alpha 2 alpha 3 heterotrimers and is chemically like vertebrate Type V collagen. On the other hand, sea anemone mesogloea collagen from the class Anthozoa was previously reported to comprise (alpha)3 homotrimers (Katzman, R. L., and Kang, A. H. (1972) J. Biol. Chem. 247, 5486-5489). On the basis of these findings, we assume that alpha 1 alpha 2 alpha 3 heterotrimers arose in evolution with the divergence of Scyphozoa and Anthozoa.

Amino Acids↗
PubMed2004

Biophysical characterization of natural and mutant fluorescent proteins cloned from zooxanthellate corals.

Two novel colored fluorescent proteins were cloned and biophysically characterized from zooxanthellate corals (Anthozoa). A cyan fluorescent protein derived from the coral Montastrea cavernosa (mcCFP) is a trimeric complex with strong blue-shifted excitation and emission maxima at 432 and 477 nm, respectively. The native complex has a fluorescence lifetime of 2.66+/-0.01 ns and an inferred absolute quantum yield of 0.385. The spectroscopic properties of a green fluorescent protein cloned from Meandrina meandrites (mmGFP) resemble the commercially available GFP derived originally from the hydrozoan Aequorea victoria (avGFP). mmGFP is a monomeric protein with an excitation maximum at 398 nm and an emission maximum at 505 nm, a fluorescence lifetime of 3.10+/-0.01 ns and an absolute quantum yield of 0.645. Sequence homology with avGFP and the red fluorescent protein (DsRed) indicates that the proteins adopt the classic beta-barrel configuration with 11 beta-strands. The three amino acid residues that comprise the chromophore are QYG for mcCFP and TYG for mmGFP, compared with SYG for avGFP. A single point mutation, Ser-110 to Asn, was introduced into mmGFP by random mutagenesis. Denaturation and refolding experiments showed that the mutant has reduced aggregation, increased solubility and more efficient refolding relative to the wild type. Time-resolved emission lifetimes and anisotropies suggest that the electronic structure of the chromophore is highly dependent on the protonation state of adjoining residues.

Animals↗
PubMed2006

Components of both major axial patterning systems of the Bilateria are differentially expressed along the primary axis of a 'radiate' animal, the anthozoan cnidarian Acropora millepora.

Cnidarians are animals with a single (oral/aboral) overt body axis and with origins that nominally predate bilaterality. To better understand the evolution of axial patterning mechanisms, we characterized genes from the coral, Acropora millepora (Class Anthozoa) that are considered to be unambiguous markers of the bilaterian anterior/posterior and dorsal/ventral axes. Homologs of Otx/otd and Emx/ems, definitive anterior markers across the Bilateria, are expressed at opposite ends of the Acropora larva; otxA-Am initially around the blastopore and later preferentially toward the oral end in the ectoderm, and emx-Am predominantly in putative neurons in the aboral half of the planula larva, in a domain overlapping that of cnox-2Am, a Gsh/ind gene. The Acropora homologs of Pax-3/7, NKX2.1/vnd and Msx/msh are expressed in axially restricted and largely non-overlapping patterns in larval ectoderm. In Acropora, components of both the D/V and A/P patterning systems of bilateral animals are therefore expressed in regionally restricted patterns along the single overt body axis of the planula larva, and two 'anterior' markers are expressed at opposite ends of the axis. Thus, although some specific gene functions appear to be conserved between cnidarians and higher animals, no simple relationship exists between axial patterning systems in the two groups.

Amino Acid Sequence↗