72 research outputs found

    Evaluation of molecular makers for species phylogeny of genus Acropora (Cnidaria; Scleractinia; Acroporidae)

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    Acropora is the most speciose genus in coral reef with 113 species currently described. Diversified morphology and potential of cross-species hybridization have drawn our attention in defining the species boundary, constructing species-level phylogeny, and inferring mechanism of speciation for this genus. Although endeavours have been taking in developing molecular markers in the last decade, several unique features such as slow evolution of mitochondrial genome and abundant ribosomal pseudogenes of Acropora neither provide little resolution for phylogenetic inference, nor equivocal conclusions in contrast to phylogenies based on fossil records and morphological characters. In this study, we evaluated 4 molecular markers, including mitochondrial cytochrome b gene (Cytb), mitochondrial intergenic spacer spanning between Cytb and ND gene (mtigs), mini-collagen intron 2 (mci2), and nuclear histone 2a and 2b gene (H2ab), for constructing species phylogeny of genus Acropora. All the 4 loci supported the two subgenera, lsopora and Acropora, as two distinct evolutionary lineages, and relocated Acropora togianensis as the fifth species in the‱ subgenus lsopora. However, Cytb, mtigs, and mci2 suffering from either low variability or sharing unsorted polymorphisms between the Caribbean and Indo-Pacific species provided no further resolution in resolving phylogeny in subgenus Acropora. In contrast, phylogeny constructed based on h2ab gene using Bayesian approach supported, in part, to Wallace (1999), that A. humilis group and A. austera form the basal clades of morphological phylogeny. The utility of nuclear coding genes in. resolving. species phylogeny of Acropora is highlighted

    Synthesis of Indium Nanowires by Galvanic Displacement and Their Optical Properties

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    <p>Abstract</p> <p>Single crystalline indium nanowires were prepared on Zn substrate which had been treated in concentrated sulphuric acid by galvanic displacement in the 0.002 mol L<sup>&#8722;1</sup>In<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>-0.002 mol L<sup>&#8722;1</sup>SeO<sub>2</sub>-0.02 mol L<sup>&#8722;1</sup>SDS-0.01 mol L<sup>&#8722;1</sup>citric acid aqueous solution. The typical diameter of indium nanowires is 30 nm and most of the nanowires are over 30 &#956;m in length. XRD, HRTEM, SAED and structural simulation clearly demonstrate that indium nanowires are single-crystalline with the tetragonal structure, the growth direction of the nanowires is along [100] facet. The UV-Vis absorption spectra showed that indium nanowires display typical transverse resonance of SPR properties. The surfactant (SDS) and the pretreatment of Zn substrate play an important role in the growth process. The mechanism of indium nanowires growth is the synergic effect of treated Zn substrate (hard template) and SDS (soft template).</p

    An Indo-Pacifc coral spawning database

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    The discovery of multi-species synchronous spawning of scleractinian corals on the Great Barrier Reef in the 1980s stimulated an extraordinary effort to document spawning times in other parts of the globe. Unfortunately, most of these data remain unpublished which limits our understanding of regional and global reproductive patterns. The Coral Spawning Database (CSD) collates much of these disparate data into a single place. The CSD includes 6178 observations (3085 of which were unpublished) of the time or day of spawning for over 300 scleractinian species in 61 genera from 101 sites in the Indo-Pacific. The goal of the CSD is to provide open access to coral spawning data to accelerate our understanding of coral reproductive biology and to provide a baseline against which to evaluate any future changes in reproductive phenology

    Effect of Inorganic and Organic Carbon Enrichments (DIC and DOC) on the Photosynthesis and Calcification Rates of Two Calcifying Green Algae from a Caribbean Reef Lagoon

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    Coral reefs worldwide are affected by increasing dissolved inorganic carbon (DIC) and organic carbon (DOC) concentrations due to ocean acidification (OA) and coastal eutrophication. These two stressors can occur simultaneously, particularly in near-shore reef environments with increasing anthropogenic pressure. However, experimental studies on how elevated DIC and DOC interact are scarce and fundamental to understanding potential synergistic effects and foreseeing future changes in coral reef function. Using an open mesocosm experiment, the present study investigated the impact of elevated DIC (pHNBS: 8.2 and 7.8; pCO2: 377 and 1076 ?atm) and DOC (added as 833 ?mol L-1 of glucose) on calcification and photosynthesis rates of two common calcifying green algae, Halimeda incrassata and Udotea flabellum, in a shallow reef environment. Our results revealed that under elevated DIC, algal photosynthesis decreased similarly for both species, but calcification was more affected in H. incrassata, which also showed carbonate dissolution rates. Elevated DOC reduced photosynthesis and calcification rates in H. incrassata, while in U. flabellum photosynthesis was unaffected and thalus calcification was severely impaired. The combined treatment showed an antagonistic effect of elevated DIC and DOC on the photosynthesis and calcification rates of H. incrassata, and an additive effect in U. flabellum. We conclude that the dominant sand dweller H. incrassata is more negatively affected by both DIC and DOC enrichments, but that their impact could be mitigated when they occur simultaneously. In contrast, U. flabellum can be less affected in coastal eutrophic waters by elevated DIC, but its contribution to reef carbonate sediment production could be further reduced. Accordingly, while the capacity of environmental eutrophication to exacerbate the impact of OA on algal-derived carbonate sand production seems to be species-specific, significant reductions can be expected under future OA scenarios, with important consequences for beach erosion and coastal sediment dynamics

    Physiological and biochemical performances of menthol-induced aposymbiotic corals.

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    The unique mutualism between corals and their photosynthetic zooxanthellae (Symbiodinium spp.) is the driving force behind functional assemblages of coral reefs. However, the respective roles of hosts and Symbiodinium in this endosymbiotic association, particularly in response to environmental challenges (e.g., high sea surface temperatures), remain unsettled. One of the key obstacles is to produce and maintain aposymbiotic coral hosts for experimental purposes. In this study, a simple and gentle protocol to generate aposymbiotic coral hosts (Isopora palifera and Stylophora pistillata) was developed using repeated incubation in menthol/artificial seawater (ASW) medium under light and in ASW in darkness, which depleted more than 99% of Symbiodinium from the host within 4∌8 days. As indicated by the respiration rate, energy metabolism (by malate dehydrogenase activity), and nitrogen metabolism (by glutamate dehydrogenase activity and profiles of free amino acids), the physiological and biochemical performances of the menthol-induced aposymbiotic corals were comparable to their symbiotic counterparts without nutrient supplementation (e.g., for Stylophora) or with a nutrient supplement containing glycerol, vitamins, and a host mimic of free amino acid mixture (e.g., for Isopora). Differences in biochemical responses to menthol-induced bleaching between Stylophora and Isopora were attributed to the former digesting Symbiodinium rather than expelling the algae live as found in the latter species. Our studies showed that menthol could successfully bleach corals and provided aposymbiotic corals for further exploration of coral-alga symbioses

    Resurrecting a subgenus to genus: Molecular phylogeny of Euphyllia and Fimbriaphyllia (order Scleractinia; family Euphyllidae; clade V)

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    Background. The corallum is crucial in building coral reefs and in diagnosing systematic relationships in the order Scleractinia. However, molecular phylogenetic analyses revealed a paraphyly in a majority of traditional families and genera among Scleractinia showing that other biological attributes of the coral, such as polyp morphology and reproductive traits, are underutilized. Among scleractinian genera, the Euphyllia, with nine nominal species in the Indo-Pacific region, is one of the groups that await phylogenetic resolution. Multiple genetic markers were used to construct the phylogeny of six Euphyllia species, namely E. ancora, E. divisa, E. glabrescens, E. paraancora, E. paradivisa, and E. yaeyamaensis. The phylogeny guided the inferences on the contributions of the colony structure, polyp morphology, and life history traits to the systematics of the largest genus in Euphyllidae (clade V) and, by extension, to the rest of clade V. Results. Analyses of cytochrome oxidase 1 (cox1), cytochrome b (cytb), and ÎČ- tubulin genes of 36 colonies representing Euphyllia and a confamilial species, Galaxea fascicularis, reveal two distinct groups in the Euphyllia that originated from different ancestors. Euphyllia glabrescens formed a separate group. Euphyllia ancora, E. divisa, E. paraancora, E. paradivisa, and E. yaeyamaensis clustered together and diverged from the same ancestor as G. fascicularis. The 30-end of the cox1 gene of Euphyllia was able to distinguish morphospecies. Discussion. Species of Euphyllia were traditionally classified into two subgenera, Euphyllia and Fimbriaphyllia, which represented a dichotomy on colony structure. The paraphyletic groups retained the original members of the subgenera providing a strong basis for recognizing Fimbriaphyllia as a genus. However, colony structure was found to be a convergent trait between Euphyllia and Fimbriaphyllia, while polyp shape and length, sexuality, and reproductive mode defined the dichotomy better. Species in a genus are distinguished by combining polyp morphology and colony form. The cluster of E. glabrescens of the Euphyllia group is a hermaphroditic brooder with long, tubular tentacles with knob-like tips, and a phaceloid colony structure. The Fimbriaphyllia group, with F. paraancora, F. paradivisa, F. ancora, F. divisa, and F. yaeyamaensis, are gonochoric broadcast spawners with short polyps, mixed types of tentacle shapes, and a phaceloid or flabello-meandroid skeleton. Soft-tissue morphology of G. fascicularis and Ctenella chagius were found to be consistent with the dichotomy. Conclusions. The paraphyly of the original members of the previous subgenera justify recognizing Fimbriaphyllia as a genus. The integrated approach demonstrates that combining polyp features, reproductive traits, and skeletal morphology is of high systematic value not just to Euphyllia and Fimbriaphyllia but also to clade V; thus, laying the groundwork for resolving the phylogeny of clade V. © 2017 Luzon et al

    Seventy-four universal primers for characterizing the complete mitochondrial genomes of scleractinian corals (Cnidaria; Anthozoa)

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    Use of universal primers designed from a public DNA database can accelerate characterization of mitochondrial (mt) genomes for targeted taxa by polymerase chain reaction (PCR) amplification and direct DNA sequencing. This approach can obtain large amounts of mt information for phylogenetic inferences at lower costs and in less time. In this study, 88 primers were designed from 13 published scleractinian mt genomes, and these were tested on Euphyllia ancora, Galaxea fascicularis, Fungiacyathus stephanus, Porites okinawensis, Goniopora columna, Tubastraea coccinea, Pavona venosa, Oulastrea crispata, and Polycyathus sp., representing 7 families of complex and robust corals. Seventy-four of the 88 primers (84.1%) successfully amplified completed mt genomes of these 9 corals. Several unique features were identified, including a group I intron insertion in the cytochrome oxidase subunit I (COI) genes of Por. okinawensis, Gon. columna, T. coccinea, and F. stephanus and an extended length of the 3'-end of the COI gene of E. ancora. Preliminary tests using a subset of primers successfully obtained the COI 3'-end of Euphyllia representatives, and the resulting species phylogeny is in agreement with corallite characters and tentacle shapes. The universal primers provided herein effectively decoded scleractinian mt genomes, and can be used to reveal different levels of molecular phylogenetic inferences in scleractinian corals
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