Gorgonian Octocorals Research Articles

Phylogenetic reconstruction using secondary structures of Internal Transcribed Spacer 2 (ITS2, rDNA): finding the molecular and morphological gap in Caribbean gorgonian corals

BackgroundMost phylogenetic studies using current methods have focused on primary DNA sequence information. However, RNA secondary structures are particularly useful in systematics because they include characteristics, not found in the primary sequence, that give "morphological" information. Despite the number of recent molecular studies on octocorals, there is no consensus opinion about a region that carries enough phylogenetic resolution to solve intrageneric or close species relationships. Moreover, intrageneric morphological information by itself does not always produce accurate phylogenies; intra-species comparisons can reveal greater differences than intra-generic ones. The search for new phylogenetic approaches, such as by RNA secondary structure analysis, is therefore a priority in octocoral research.ResultsInitially, twelve predicted RNA secondary structures were reconstructed to provide the basic information for phylogenetic analyses; they accorded with the 6 helicoidal ring model, also present in other groups of corals and eukaryotes. We obtained three similar topologies for nine species of the Caribbean gorgonian genus Eunicea (candelabrum corals) with two sister taxa as outgroups (genera Plexaura and Pseudoplexaura) on the basis of molecular morphometrics of ITS2 RNA secondary structures only, traditional primary sequence analyses and maximum likelihood, and a Bayesian analysis of the combined data. The latter approach allowed us to include both primary sequence and RNA molecular morphometrics; each data partition was allowed to have a different evolution rate. In addition, each helix was partitioned as if it had evolved at a distinct rate. Plexaura flexuosa was found to group within Eunicea; this was best supported by both the molecular morphometrics and combined analyses. We suggest Eunicea flexuosa (Lamouroux, 1821) comb. nov., and we present a new species description including Scanning Electron Microscopy (SEM) images of morphological characteristics (sclerites). Eunicea flexuosa, E. pallida, E. laxispica and E. mammosa formed a separate clade in the molecular phylogenies, and were reciprocally monophyletic with respect to other Eunicea (Euniceopsis subgenus, e.g. E. tourneforti and E. laciniata) in the molecular morphometrics tree, with the exception of E. fusca. Moreover, we suggest a new diagnostic character for Eunicea, also present in E. flexuosa: middle layer sclerites > 1 mm in length.ConclusionITS2 was a reliable sequence for intrageneric studies in gorgonian octocorals because of the amount of phylogenetic signal, and was corroborated against morphological characters separating Eunicea from Plexaura. The ITS2 RNA secondary structure approach to phylogeny presented here did not rely on alignment methods such as INDELS, but provided clearly homologous characters for partition analysis and RNA molecular morphometrics. These approaches support the divergence of Eunicea flexuosa comb. nov. from the outgroup Plexaura, although it has been considered part of this outgroup for nearly two centuries because of morphological resemblance.

Eupalmerin acetate, a novel anticancer agent from Caribbean gorgonian octocorals, induces apoptosis in malignant glioma cells via the c-Jun NH2-terminal kinase pathway

The marine ecosystem is a vast but largely untapped resource for potential naturally based medicines. We tested 15 compounds derived from organisms found in the Caribbean Sea (14 gorgonian octocoral-derived compounds and one sponge-derived compound) for their anticancer effects on human malignant glioma U87-MG and U373-MG cells. Eupalmerin acetate (EPA) was chosen as the lead compound based on its longer-term stability and greater cytotoxicity than those of the other compounds we tested in these cell types. EPA induced G(2)-M cell cycle arrest and apoptosis via the mitochondrial pathway; it translocated Bax from the cytoplasm to the mitochondria and dissipated the mitochondrial transmembrane potential in both cell types. EPA was found to increase phosphorylated c-Jun NH(2)-terminal kinase (JNK) by >50% in both U87-MG and U373-MG cells. A specific JNK inhibitor, SP600125, inhibited EPA-induced apoptosis, confirming the involvement of the JNK pathway in EPA-induced apoptotic cell death. Furthermore, 7 days of daily intratumoral injections of EPA significantly suppressed the growth of s.c. malignant glioma xenografts (P < 0.01, on day 19). These results indicate that EPA is therapeutically effective against malignant glioma cells in vitro and in vivo and that it, or a similar marine-based compound, may hold promise as a clinical anticancer agent.

A biogenetically patterned synthetic approach to the unusual furan methylenecyclobutanol moiety in providencin

Irradiation of a solution of α,β-unsaturated aldehyde 10 in benzene leads to the methylenecyclobutanol 11 by way of a novel intramolecular C–H insertion reaction. The conversion of 10 into 11 has relevance to the possible origin of the cyclobutane ring-based furanocembrane providencin 1 found in gorgonian octocorals.

Six microsatellite loci from the deep‐sea coral Corallium lauuense (Octocorallia: Coralliidae) from the islands and seamounts of the Hawaiian archipelago

AbstractGorgonian octocorals are among the dominant deep‐sea benthic taxa of many seamounts. Seamount fauna are threatened by destructive fisheries practices, yet little is known about the physical and biological processes that maintain species on seamounts. Few informative molecular markers have been found in deep‐water corals or in gorgonian octocorals. Here we report the characterization of six highly polymorphic microsatellite loci for the deep‐sea precious coral Corallium lauuense from Hawaii using enriched genomic DNA libraries. These loci are being used to examine gene flow and stock structure among seamount and island populations to better understand dispersal and connectivity of seamount species.

Pseudopterosins P—V, New Compounds from the Gorgonian Octocoral Pseudopterogorgia elisabethae from Providencia Island, Colombian Caribbean.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Cloning and Characterization of Microsatellite Loci in a Gorgonian Coral, Junceella juncea (Anthozoa; Octocorallia; Ellisellidae) and Its Application in Clonal Genotyping

We attempted to isolate microsatellites from a Symbiodinium-free gorgonian octocoral, Junceella juncea, using two methods, partial genomic library screening and enrichment. Among the 3856 clones screened by the partial library method, 10 possibly positive signals were found, and 3 of them could be used to design primers and amplified consistently. In contrast, only one locus isolated by the enrichment method gave reliable amplification and was useful. The results indicate that microsatellites are rare in Junceella juncea, as reported for other cnidarians. Overall, we obtained 4 polymorphic loci to test the feasibility in investigating clonal structure of J. juncea. A total of 40 multilocus genotypes were found among 152 colonies, and the number of genotypes (clones) identified at 7 reefs ranged from 2 to 16. The results of a nonmetric multidimensional scaling analysis indicated the recruitment of J. juncea populations mainly comes from self-retention. These novel microsatellite loci will provide a useful tool to study clonal structure and population genetics for J. juncea in the future.

Evolution and dynamics of branching colonial form in marine modular cnidarians: gorgonian octocorals

Evolution and dynamics of branching colonial form in marine modular cnidarians: gorgonian octocorals

Transplantation of Gorgonian Octocorals for in situ Experimental Manipulations

Transplantation of Gorgonian Octocorals for in situ Experimental Manipulations

Homopseudopteroxazole, a new antimycobacterial diterpene alkaloid from Pseudopterogorgia elisabethae.

In the course of our study to find novel antimycobacterial secondary metabolites from Caribbean gorgonian octocorals, we have isolated a new diterpene alkaloid, namely, homopseudopteroxazole (1), as a minor constituent of the hexane extract from the sea plume Pseudopterogorgia elisabethae. Its structure was deduced by interpretation of combined spectroscopic data, including extensive 1D and 2D NMR measurements, and NMR spectral comparisons with known amphilectane models. Biological screening studies indicate that homopseudopteroxazole (1) is a strong growth inhibitor of Mycobacterium tuberculosis H(37)Rv.

Phylogenetic analyses among octocorals (Cnidaria): mitochondrial and nuclear DNA sequences (lsu-rRNA, 16S and ssu-rRNA, 18S) support two convergent clades of branching gorgonians

Gorgonian octocorals lack corroborated hypotheses of phylogeny. This study reconstructs genealogical relationships among some octocoral species based on published DNA sequences from the large ribosomal subunit of the mitochondrial RNA (lsu-rRNA, 16S: 524 bp and 21 species) and the small subunit of the nuclear RNA (ssu-rRNA, 18S: 1815 bp and 13 spp) using information from insertions–deletions (INDELS) and the predicted secondary structure of the lsu-rRNA (16S). There were seven short (3–10 bp) INDELS in the 18S with consistent phylogenetic information. The INDELS in the 16S corresponded to informative signature sequences homologous to the G13 helix found in Escherichia coli. We found two main groups of gorgonian octocorals using a maximum parsimony analysis of the two genes. One group corresponds to deep-water taxa including species from the suborders Calcaxonia and Scleraxonia characterized by an enlargement of the G13 helix. The second group has species from Alcyoniina, Holaxonia and again Scleraxonia characterized by insertions in the 18S. Gorgonian corals, branching colonies with a gorgonin-containing flexible multilayered axis (Holaxonia and Calcaxonia), do not form a monophyletic group. These corroborated results from maternally inherited ( 16S) and biparentally inherited ( 18S) genes support a hypothesis of independent evolution of branching in the two octocoral clades.

The Heterocyclic Natural Products of Gorgonian Corals of Genus Briareum Exclusive of Briarane‐Type Diterpenoids

AbstractFor Abstract see ChemInform Abstract in Full Text.

The Heterocyclic Natural Products of Gorgonian Corals of Genus Briareum Exclusive of Briarane-Type Diterpenoids

An overview on the heterocyclic natural products of gorgonian octocorals of genus Briareum is presented. Based on previous studies, most of the heterocyclic natural products from Briareum are diterpenoid metabolites, including eunicellin, asbestinane, cembrane, and briarane-type derivatives. The structures, names, biological activities, and references of these natural products exclusive of briaranes are described in this review.

Calyculaglycosides D and E, novel cembrane glycosides from the Caribbean gorgonian octocoral Eunicea species and structural revision of the aglycon of calyculaglycosides A-C.

A recent investigation of the constituents of Eunicea sp. from Colombia and Puerto Rico has provided two novel cembrane glycosides, calyculaglycosides D (6) and E (7), and a new cembranoid diterpene in free form, (+)-nephthenol (4). Metabolites 6 and 7 possess a glycosyl-fused cembrane skeleton with a 1S configuration. Biogenetic considerations have led to a revision of the previously assigned dilophol skeleton of calyculaglycosides A-C, which was confirmed by extensive 2D NMR investigation and a chemical degradation study. Consequently, the true structures for calyculaglycosides A-C are 8-10, respectively, not 1-3. This is the first report of the occurrence of marine diterpene glycosides having a cembrane aglycon.

Possible vestige of early phosphatic biomineralization in gorgonian octocorals (Coelenterata)

Research Article| May 01, 2000 Possible vestige of early phosphatic biomineralization in gorgonian octocorals (Coelenterata) Ian G. Macintyre; Ian G. Macintyre 1Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, USA Search for other works by this author on: GSW Google Scholar Frederick M. Bayer; Frederick M. Bayer 2Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, USA Search for other works by this author on: GSW Google Scholar M. Amelia V. Logan; M. Amelia V. Logan 3Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, USA Search for other works by this author on: GSW Google Scholar H. Catherine W. Skinner H. Catherine W. Skinner 4Department of Geology and Geophysics, Yale University, P.O. Box 208109, New Haven, Connecticut 06520, USA Search for other works by this author on: GSW Google Scholar Geology (2000) 28 (5): 455–458. https://doi.org/10.1130/0091-7613(2000)28<455:PVOEPB>2.0.CO;2 Article history received: 05 Nov 1999 rev-recd: 07 Feb 2000 accepted: 16 Feb 2000 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Ian G. Macintyre, Frederick M. Bayer, M. Amelia V. Logan, H. Catherine W. Skinner; Possible vestige of early phosphatic biomineralization in gorgonian octocorals (Coelenterata). Geology 2000;; 28 (5): 455–458. doi: https://doi.org/10.1130/0091-7613(2000)28<455:PVOEPB>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Skeletal carbonate hydroxylapatite, heretofore unknown in modern coelenterates, has been found in the axes and holdfasts of the gorgonian octocoral family Gorgoniidae. This carbonate apatite is a distinctive feature of this family of octocorals and may indicate a previous history of phosphatic skeletal mineralization within this phylum. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Chemical aspects of mass spawning in corals. II. (-)-Epi-thunbergol, the sperm attractant in the eggs of the soft coral Lobophytum crassum (Cnidaria: Octocorallia)

The eggs of Lobophytum crassum Von Marenzeller, 1886, collected at Magnetic Island (19°10′S; 146°52′E) in October or November between 1983 and 1993, contained significant amounts (6% dry weight) of (-)-epi-thunbergol, in addition to other terpenoid metabolites also present in the parent colony. (-)-Epi-thunbergol was not present in the tissues of the releasing colony. Using fluorocarbon droplets impregnated with the chemotactic molecules and a videomicroscopic technique for the direct observation of sperm under the influence of attractant molecules, we showed that (-)-epi-thunbergol, whether isolated from L. crassum or from a gorgonian octocoral (Briareum sp.), significantly attracts sperm from L. crassum colonies. Attraction could be detected using direct observation at concentrations as low as 3.25 μg ml-1. This is the first evidence for sperm chemotaxis in the Alcyonacea. Eggs from L compactum, a common alcyonacean coral at Orpheus Island (18°36′S; 146°29′E) contained (-)-thunbergol as the egg-specific compound. L. compactum was not found at Magnetic Island. (-)-Thunbergol from L. compactum and (+)-thunbergol from a Douglas fir tree both showed levels of attraction similar to (-)-epi-thunbergol against L. crassum sperm. Although L. crassum sperm were apparently neither stereo- nor enantio-specific in their selectivity for chemotactic molecules, (-)-epi-thunbergol was identified as the natural sperm attractant in the eggs of L. crassum.

Additional dolabellane diterpenes from the Caribbean gorgonian octocoral Eunicea laciniata.

The Caribbean gorgonian octocoral Eunicea laciniata from the coasts of Palomino Island, Puerto Rico, has yielded four known and five new diterpenes based on the dolabellane ring system. The structures of the novel compounds 3-7 were established by interpretation of their spectral data. Some of these new compounds showed weak cytotoxicity against HeLa cells.

Acerosterol, a Novel Polyhydroxylated Sterol from the Gorgonian Octocoral Pseudopterogorgia acerosa

A new tetrahydroxysterol, acerosterol [2], has been isolated from the gorgonian octocoral Pseudopterogorgia acerosa. The structure has been determined to 4α,23,24(R)-trimethyl-5α-cholest-22E-ene-1α,3β,6β,11α-tetraol on the basis of 2D nmr spectroscopy

Observations on the Size, Predators and Tumor-Like Outgrowths of Gorgonian Octocoral Colonies in the Area of Santa Marta, Caribbean Coast of Colombia

Gorgonian communities of the Santa Marta area are dominated by species with large numbers of large colonies (height >40 cm) in contrast to that reported for other Caribbean sites where species with large numbers of small (<10 cm in>height) colonies are predominant. Cyphoma gibbosum and Hermodice carunculata are the main predators of gorgonians in the area, but Cyphoma signatum and the fishes Alutera scripta, Acanthostracion quadricornis and Chaetodipterus faber were also observed feeding on gorgonians. Tumor-like outgrowths commonly appear in species of Pseudoplexaura and in Plexaura flexuosa and contain a chlorophyte Entocladia sp. Tubercle-like outgrowths in Plexaura homomalla, P. flexuosa, Pseudopterogorgia americana and Plexaurella grisea were found to contain a variety of invertebrates.

Surface characterisation of two gorgonian coral species: Implications for a natural antifouling defence

The natural, fouling‐resistant surfaces of the gorgonian octocorals Pseudopterogorgia americana (Gmelin) and Pseudopterogorgia acerosa (Pallas) were characterised utilising a variety of surface analysis techniques. Samples were collected in April and November 1987 from a natural population. No significant differences in bacterial surface populations were measured between species or between sampling periods. Contact angle analyses suggest that these natural surfaces have low surface energies (γ c=23–27 mN/m) that are in the range previously correlated with minimal bioadhesiveness. Gorgonians may utilise this minimal adhesiveness as a passive fouling‐resistance mechanism in conjunction with other antifouling defences.

Fouling and gastropod predation: consequences of grazing for a tropical octocoral

The ovulid gastropod Cyphoma gibbosum Linnaeus is a specialist consumer of gorgonian octocorals. Although the direct effects of its feeding do not appear to be great, the indirect consequences may be substantial. An 8 wk study of the gorgonian Plexaura hornornalla Esper in Curaqao found that C. g~bbosum occurred primarily on the lower 30 cm of colonies, and that there were significant correlations between C glbbosum density and the extent of colony fouling on the lower 30 cm of colonies. This correlation occurred whether one measured in~tial fouling, final fouhng, or change in fouling during the 8 wk. There were no significant correlations of C. gibbosum density and fouling for colony portions more than 30 cm above the holdfast. These findings and direct observations in the field suggest that feeding by C. gibbosum increases fouling of gorgonians by exposing the axial skeleton and providing settling sites for fouling propagules. Because fecundity of P. homornalla is reduced when fouhng separates colonies into a series of smaller aggregates, the indirect effects of C. g~bbosum grazing could strongly affect the fitness of P. hornornalla and other gorgonians.