Literatura académica sobre el tema "Corals Dinoflagellates Corals Dinoflagellates Symbiosis. Coral reef ecology"
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Artículos de revistas sobre el tema "Corals Dinoflagellates Corals Dinoflagellates Symbiosis. Coral reef ecology"
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Henderson, Meegan, Tracy Ainsworth y Ove Hoegh-Guldberg. "Coral microbial ecology under the microscope". Microbiology Australia 28, n.º 3 (2007): 111. http://dx.doi.org/10.1071/ma07111.
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Increasing episodes of mass coral bleaching and a growing number of reports of coral disease epizootics have led to an expanding research field investigating the microbial ecology of reef building corals. Corals reside in a complex ecosystem and form intimate symbiotic relationships with eukaryotic dinoflagellates (commonly called zooxanthellae), which have been well studied. Less understood is the complex interactions that corals form with Bacteria, Archaea and viruses, all of which play an important functional role in coral health. Understanding how the coral animal and its symbiotic partners (eukaryotic, bacterial, archeal and viral) are influenced by environmental perturbations such as global climate change, rising sea surface temperatures and increasing anthropogenic inputs into the ecosystem such as nutrients, is the driving factor behind this expanding microbial discipline.
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Rosic, Nedeljka N. y Sophie Dove. "Mycosporine-Like Amino Acids from Coral Dinoflagellates". Applied and Environmental Microbiology 77, n.º 24 (14 de octubre de 2011): 8478–86. http://dx.doi.org/10.1128/aem.05870-11.
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ABSTRACTCoral reefs are one of the most important marine ecosystems, providing habitat for approximately a quarter of all marine organisms. Within the foundation of this ecosystem, reef-building corals form mutualistic symbioses with unicellular photosynthetic dinoflagellates of the genusSymbiodinium. Exposure to UV radiation (UVR) (280 to 400 nm) especially when combined with thermal stress has been recognized as an important abiotic factor leading to the loss of algal symbionts from coral tissue and/or a reduction in their pigment concentration and coral bleaching. UVR may damage biological macromolecules, increase the level of mutagenesis in cells, and destabilize the symbiosis between the coral host and their dinoflagellate symbionts. In nature, corals and other marine organisms are protected from harmful UVR through several important photoprotective mechanisms that include the synthesis of UV-absorbing compounds such as mycosporine-like amino acids (MAAs). MAAs are small (<400-Da), colorless, water-soluble compounds made of a cyclohexenone or cyclohexenimine chromophore that is bound to an amino acid residue or its imino alcohol. These secondary metabolites are natural biological sunscreens characterized by a maximum absorbance in the UVA and UVB ranges of 310 to 362 nm. In addition to their photoprotective role, MAAs act as antioxidants scavenging reactive oxygen species (ROS) and suppressing singlet oxygen-induced damage. It has been proposed that MAAs are synthesized during the first part of the shikimate pathway, and recently, it has been suggested that they are synthesized in the pentose phosphate pathway. The shikimate pathway is not found in animals, but in plants and microbes, it connects the metabolism of carbohydrates to the biosynthesis of aromatic compounds. However, both the complete enzymatic pathway of MAA synthesis and the extent of their regulation by environmental conditions are not known. This minireview discusses the current knowledge of MAA synthesis, illustrates the diversity of MAA functions, and opens new perspectives for future applications of MAAs in biotechnology.
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Jones, Ross J., Selina Ward, Affendi Yang Amri y Ove Hoegh-Guldberg. "Changes in quantum efficiency of Photosystem II of symbiotic dinoflagellates of corals after heat stress, and of bleached corals sampled after the 1998 Great Barrier Reef mass bleaching event". Marine and Freshwater Research 51, n.º 1 (2000): 63. http://dx.doi.org/10.1071/mf99100.
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Pulse–amplitude–modulation chlorophyll fluorometry was used to examine changes in dark-adapted Fv/Fm of endosymbiotic dinoflagellate microalgae within the tissues of the temperate coral Plesiastrea versipora exposed to elevated seawater temperature. The Fv/Fm was markedly reduced following exposure of corals to 28°C for 48 h. When corals were returned to ambient (24°C) conditions, Fv/Fm increased in an initial rapid and then secondary slower phase. Tissue discolouration (coral bleaching), caused by a significant decrease in the density of algae, was observed during the first 2–3 days of the recovery period. After 14 days, Fv/Fm was still significantly lower than in control corals. The recovery of Fv/Fm is discussed in terms of repair processes within the symbiotic algae, division of healthy algae and also the selective removal of photo-damaged dinoflagellates. Under field conditions, bleached corals sampled at Heron Island Reef during a bleaching event had significantly lower Fv/Fm than non-bleached colonies; four months after the bleaching event, there were no differences in F v /F m or algal density in corals marked as having bleached or having shown no signs of colour loss. The results of this laboratory and field study are consistent with the hypothesis that an impairment of photosynthesis occurs during heat-stress, and is the underlying cause of coral bleaching.
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Shoguchi, Eiichi, Yuki Yoshioka, Chuya Shinzato, Asuka Arimoto, Debashish Bhattacharya y Noriyuki Satoh. "Correlation between Organelle Genetic Variation and RNA Editing in Dinoflagellates Associated with the Coral Acropora digitifera". Genome Biology and Evolution 12, n.º 3 (27 de febrero de 2020): 203–9. http://dx.doi.org/10.1093/gbe/evaa042.
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Abstract In order to develop successful strategies for coral reef preservation, it is critical that the biology of both host corals and symbiotic algae are investigated. In the Ryukyu Archipelago, which encompasses many islands spread over ∼500 km of the Pacific Ocean, four major populations of the coral Acropora digitifera have been studied using whole-genome shotgun (WGS) sequence analysis (Shinzato C, Mungpakdee S, Arakaki N, Satoh N. 2015. Genome-wide single-nucleotide polymorphism (SNP) analysis explains coral diversity and recovery in the Ryukyu Archipelago. Sci Rep. 5:18211.). In contrast, the diversity of the symbiotic dinoflagellates associated with these A. digitifera populations is unknown. It is therefore unclear if these two core components of the coral holobiont share a common evolutionary history. This issue can be addressed for the symbiotic algal populations by studying the organelle genomes of their mitochondria and plastids. Here, we analyzed WGS data from ∼150 adult A. digitifera, and by mapping reads to the available reference genome sequences, we extracted 2,250 sequences representing 15 organelle genes of Symbiodiniaceae. Molecular phylogenetic analyses of these mitochondrial and plastid gene sets revealed that A. digitifera from the southern Yaeyama islands harbor a different Symbiodiniaceae population than the islands of Okinawa and Kerama in the north, indicating that the distribution of symbiont populations partially matches that of the four host populations. Interestingly, we found that numerous SNPs correspond to known RNA-edited sites in 14 of the Symbiodiniaceae organelle genes, with mitochondrial genes showing a stronger correspondence than plastid genes. These results suggest a possible correlation between RNA editing and SNPs in the two organelle genomes of symbiotic dinoflagellates.
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Lema, Kimberley A., Bette L. Willis y David G. Bourne. "Corals Form Characteristic Associations with Symbiotic Nitrogen-Fixing Bacteria". Applied and Environmental Microbiology 78, n.º 9 (17 de febrero de 2012): 3136–44. http://dx.doi.org/10.1128/aem.07800-11.
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ABSTRACTThe complex symbiotic relationship between corals and their dinoflagellate partnerSymbiodiniumis believed to be sustained through close associations with mutualistic bacterial communities, though little is known about coral associations with bacterial groups able to fix nitrogen (diazotrophs). In this study, we investigated the diversity of diazotrophic bacterial communities associated with three common coral species (Acropora millepora,Acropora muricata, andPocillopora damicormis) from three midshelf locations of the Great Barrier Reef (GBR) by profiling the conserved subunit of thenifHgene, which encodes the dinitrogenase iron protein. Comparisons of diazotrophic community diversity among coral tissue and mucus microenvironments and the surrounding seawater revealed that corals harbor diversenifHphylotypes that differ between tissue and mucus microhabitats. Coral mucusnifHsequences displayed high heterogeneity, and many bacterial groups overlapped with those found in seawater. Moreover, coral mucus diazotrophs were specific neither to coral species nor to reef location, reflecting the ephemeral nature of coral mucus. In contrast, the dominant diazotrophic bacteria in tissue samples differed among coral species, with differences remaining consistent at all three reefs, indicating that coral-diazotroph associations are species specific. Notably, dominant diazotrophs for all coral species were closely related to the bacterial group rhizobia, which represented 71% of the total sequences retrieved from tissue samples. The species specificity of coral-diazotroph associations further supports the coral holobiont model that bacterial groups associated with corals are conserved. Our results suggest that, as in terrestrial plants, rhizobia have developed a mutualistic relationship with corals and may contribute fixed nitrogen toSymbiodinium.
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Wooldridge, S. A. "A hypothesis linking sub-optimal seawater <i>p</i>CO<sub>2</sub> conditions for cnidarian-<i>Symbiodinium</i> symbioses with the exceedence of the interglacial threshold (> 260 ppmv)". Biogeosciences Discussions 8, n.º 6 (23 de noviembre de 2011): 11215–53. http://dx.doi.org/10.5194/bgd-8-11215-2011.
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Abstract. Most scleractinian corals and many other cnidarians host intracellular photosynthetic dinoflagellate symbionts ("zooxanthellae"). The zooxanthellae contribute to host metabolism and skeletogenesis to such an extent that this symbiosis is well recognised for its contribution in creating the coral reef ecosystem. The stable functioning of cnidarian symbioses is however dependent upon the host's ability to maintain demographic control of its algal partner. In this review, I explain how the modern envelope of seawater conditions found within many coral reef ecosystems (characterised by elevated temperatures, rising pCO2, and enriched nutrient levels) are antagonistic toward the dominant host processes that restrict excessive symbiont proliferation. Moreover, I outline a new hypothesis and initial evidence base, which support the suggestion that the additional "excess" zooxanthellae fraction permitted by seawater pCO2 levels beyond 260 ppmv significantly increases the propensity for symbiosis breakdown ("bleaching") in response to temperature and irradiance extremes. The relevance of this biological threshold is discussed in terms of historical reef extinction events, glacial-interglacial climate cycles and the modern decline of coral reef ecosystems.
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Wooldridge, S. A. "A hypothesis linking sub-optimal seawater <I>p</I>CO<sub>2</sub> conditions for cnidarian-<I>Symbiodinium</I> symbioses with the exceedence of the interglacial threshold (>260 ppmv)". Biogeosciences 9, n.º 5 (15 de mayo de 2012): 1709–23. http://dx.doi.org/10.5194/bg-9-1709-2012.
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Abstract. Most scleractinian corals and many other cnidarians host intracellular photosynthetic dinoflagellate symbionts ("zooxanthellae"). The zooxanthellae contribute to host metabolism and skeletogenesis to such an extent that this symbiosis is well recognised for its contribution in creating the coral reef ecosystem. The stable functioning of cnidarian symbioses is however dependent upon the host's ability to maintain demographic control of its algal partner. In this review, I explain how the modern envelope of seawater conditions found within many coral reef ecosystems (characterised by elevated temperatures, rising pCO2, and enriched nutrient levels) are antagonistic toward the dominant host processes that restrict excessive symbiont proliferation. Moreover, I outline a new hypothesis and initial evidence base, which support the suggestion that the additional "excess" zooxanthellae fraction permitted by seawater pCO2 levels beyond 260 ppmv significantly increases the propensity for symbiosis breakdown ("bleaching") in response to temperature and irradiance extremes. The relevance of this biological threshold is discussed in terms of historical reef extinction events, glacial-interglacial climate cycles and the modern decline of coral reef ecosystems.
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Frommlet, Jörg C., Maria L. Sousa, Artur Alves, Sandra I. Vieira, David J. Suggett y João Serôdio. "Coral symbiotic algae calcifyex hospitein partnership with bacteria". Proceedings of the National Academy of Sciences 112, n.º 19 (27 de abril de 2015): 6158–63. http://dx.doi.org/10.1073/pnas.1420991112.
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Dinoflagellates of the genusSymbiodiniumare commonly recognized as invertebrate endosymbionts that are of central importance for the functioning of coral reef ecosystems. However, the endosymbiotic phase withinSymbiodiniumlife history is inherently tied to a more cryptic free-living (ex hospite) phase that remains largely unexplored. Here we show that free-livingSymbiodiniumspp. in culture commonly form calcifying bacterial–algal communities that produce aragonitic spherulites and encase the dinoflagellates as endolithic cells. This process is driven bySymbiodiniumphotosynthesis but occurs only in partnership with bacteria. Our findings not only place dinoflagellates on the map of microbial–algal organomineralization processes but also point toward an endolithic phase in theSymbiodiniumlife history, a phenomenon that may provide new perspectives on the biology and ecology ofSymbiodiniumspp. and the evolutionary history of the coral–dinoflagellate symbiosis.
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González-Espinosa, PC y SD Donner. "Predicting cold-water bleaching in corals: role of temperature, and potential integration of light exposure". Marine Ecology Progress Series 642 (28 de mayo de 2020): 133–46. http://dx.doi.org/10.3354/meps13336.
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Warm-water growth and survival of corals are constrained by a set of environmental conditions such as temperature, light, nutrient levels and salinity. Water temperatures of 1 to 2°C above the usual summer maximum can trigger a phenomenon known as coral bleaching, whereby disruption of the symbiosis between coral and dinoflagellate micro-algae, living within the coral tissue, reveals the white skeleton of coral. Anomalously cold water can also lead to coral bleaching but has been the subject of limited research. Although cold-water bleaching events are less common, they can produce similar impacts on coral reefs as warm-water events. In this study, we explored the effect of temperature and light on the likelihood of cold-water coral bleaching from 1998-2017 using available bleaching observations from the Eastern Tropical Pacific and the Florida Keys. Using satellite-derived sea surface temperature, photosynthetically available radiation and light attenuation data, cold temperature and light exposure metrics were developed and then tested against the bleaching observations using logistic regression. The results show that cold-water bleaching can be best predicted with an accumulated cold-temperature metric, i.e. ‘degree cooling weeks’, analogous to the heat stress metric ‘degree heating weeks’, with high accuracy (90%) and fewer Type I and Type II errors in comparison with other models. Although light, when also considered, improved prediction accuracy, we found that the most reliable framework for cold-water bleaching prediction may be based solely on cold-temperature exposure.
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Fujita, K., M. Hikami, A. Suzuki, A. Kuroyanagi, K. Sakai, H. Kawahata y Y. Nojiri. "Effects of ocean acidification on calcification of symbiont-bearing reef foraminifers". Biogeosciences 8, n.º 8 (4 de agosto de 2011): 2089–98. http://dx.doi.org/10.5194/bg-8-2089-2011.
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Abstract. Ocean acidification (decreases in carbonate ion concentration and pH) in response to rising atmospheric pCO2 is generally expected to reduce rates of calcification by reef calcifying organisms, with potentially severe implications for coral reef ecosystems. Large, algal symbiont-bearing benthic foraminifers, which are important primary and carbonate producers in coral reefs, produce high-Mg calcite shells, whose solubility can exceed that of aragonite produced by corals, making them the "first responder" in coral reefs to the decreasing carbonate saturation state of seawater. Here we report results of culture experiments performed to assess the effects of ongoing ocean acidification on the calcification of symbiont-bearing reef foraminifers using a high-precision pCO2 control system. Living clone individuals of three foraminiferal species (Baculogypsina sphaerulata, Calcarina gaudichaudii, and Amphisorus hemprichii) were subjected to seawater at five pCO2 levels from 260 to 970 μatm. Cultured individuals were maintained for about 12 weeks in an indoor flow-through system under constant water temperature, light intensity, and photoperiod. After the experiments, the shell diameter and weight of each cultured specimen were measured. Net calcification of B. sphaerulata and C. gaudichaudii, which secrete a hyaline shell and host diatom symbionts, increased under intermediate levels of pCO2 (580 and/or 770 μatm) and decreased at a higher pCO2 level (970 μatm). Net calcification of A. hemprichii, which secretes a porcelaneous shell and hosts dinoflagellate symbionts, tended to decrease at elevated pCO2. Observed different responses between hyaline and porcelaneous species are possibly caused by the relative importance of elevated pCO2, which induces CO2 fertilization effects by algal symbionts, versus associated changes in seawater carbonate chemistry, which decreases a carbonate concentration. Our findings suggest that ongoing ocean acidification might favor symbiont-bearing reef foraminifers with hyaline shells at intermediate pCO2 levels (580 to 770 μatm) but be unfavorable to those with either hyaline or porcelaneous shells at higher pCO2 levels (near 1000 μatm).
Tesis sobre el tema "Corals Dinoflagellates Corals Dinoflagellates Symbiosis. Coral reef ecology"
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Robison, Jennifer D. "The photophysiology of symbiotic dinoflagellates (Symbiodinium) under varying light and thermal conditions and the implications for coral bleaching". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 8.14 Mb., 97 p, 2006. http://proquest.umi.com/pqdlink?did=1163244091&Fmt=7&clientId=8331&RQT=309&VName=PQD.
Texto completoLibros sobre el tema "Corals Dinoflagellates Corals Dinoflagellates Symbiosis. Coral reef ecology"
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Kirchman, David L. Symbioses and microbes. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198789406.003.0014.
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The book ends with a chapter devoted to discussing interactions between microbes and higher plants and animals. Symbiosis is sometimes used to describe all interactions, even negative ones, between organisms in persistent, close contact. This chapter focuses on interactions that benefit both partners (mutualism), or one partner while being neutral to the other (commensalism). Microbes are essential to the health and ecology of vertebrates, including Homo sapiens. Microbial cells outnumber human cells on our bodies, aiding in digestion and warding off pathogens. In consortia similar to the anaerobic food chain of anoxic sediments, microbes are essential in the digestion of plant material by deer, cattle, and sheep. Different types of microbes form symbiotic relationships with insects and help to explain their huge success in the biosphere. Protozoa are crucial for wood-boring insects, symbiotic bacteria in the genus Buchnera provide sugars to host aphids while obtaining essential amino acids in exchange, and fungi thrive in subterranean gardens before being harvested for food by ants. Symbiotic dinoflagellates directly provide organic material to support coral growth in exchange for ammonium and other nutrients. Corals are now threatened worldwide by rising oceanic temperatures, decreasing pH, and other human-caused environmental changes. At hydrothermal vents in some deep oceans, sulfur-oxidizing bacteria fuel an entire ecosystem and endosymbiotic bacteria support the growth of giant tube worms. Higher plants also have many symbiotic relationships with bacteria and fungi. Symbiotic nitrogen-fixing bacteria in legumes and other plants fix more nitrogen than free-living bacteria. Fungi associated with plant roots (“mycorrhizal”) are even more common and potentially provide plants with phosphorus as well as nitrogen. Symbiotic microbes can provide other services to their hosts, such as producing bioluminescence, needed for camouflage against predators. In the case of the bobtail squid, bioluminescence is only turned on when populations of the symbiotic bacteria reach critical levels, determined by a quorum sensing mechanism.
Capítulos de libros sobre el tema "Corals Dinoflagellates Corals Dinoflagellates Symbiosis. Coral reef ecology"
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Sheppard, Charles. "3. The architects of a reef". En Coral Reefs: A Very Short Introduction, 20–41. Oxford University Press, 2021. http://dx.doi.org/10.1093/actrade/9780198869825.003.0003.
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Coral reefs are tropical ecosystems but show global patterns. The Caribbean has about 60 reef-building coral species, while Southeast Asia has nearly 1,000, this number broadly diminishing with distance east and west from the Southeast Asian region. Diversity of corals also diminishes broadly with distance north and south of the equator. While basic patterns exist, there are several kinds of reef in the same sense that there are different kinds of forests, sometimes forming near-monocultures, sometimes with more diverse mixtures of species. Their key to success is that they house vast numbers of captive dinoflagellates that photosynthesize in a close symbiosis, which explains how these complex ecosystems persist in the absence of substantial fields of large, visible seaweeds. All deposit limestone in its aragonite form, in a way characteristic to each species, which has been used for distinguishing between species. The basic unit of a coral, the polyp, reproduces sexually, but more importantly by asexual budding, which allows for the growth of large colonies of polyps, all clones. Numerous other organisms have crucial associations with the coral polyp: bacteria and archaea especially, the whole forming what is now termed the coral holobiont. Aside from photosynthesis, corals have nematocysts in their tentacles to capture zooplankton food. Corals compete for space using these stinging cells also, amongst other methods. On any reef, soft corals are numerous, especially in the Caribbean, though these do not deposit limestone rock. Calcareous algae are crucial reef-building components too, particularly in the shallows.
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Sheppard, Charles. "5. Microbial engines of the coral reef". En Coral Reefs: A Very Short Introduction, 58–67. Oxford University Press, 2021. http://dx.doi.org/10.1093/actrade/9780198869825.003.0005.
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The symbiosis between corals and the dinoflagellates—zooxanthellae—is the key to a tight recycling of nutrients on reefs that generally thrive best in nutrient poor parts of the oceans. But several other mechanisms and species groups aid transmission of organic matter and energy along the numerous food chains of a reef. Viruses, bacteria, and archaea are key to the recycling of carbon and organic compounds, making the ‘microbial loop’, one key but invisible aspect to how the reef functions. Cyanobacteria, formerly blue-green algae, are a major part of the micro-benthos too, and are important primary producers. Protists are also hugely abundant—larger, single-celled organisms which are eukaryotes with cells with nuclei, and this group has species that exist in planktonic and benthic forms. Foraminifera are important protists, being abundant and having calcareous tests, so that they are significant sand producers in some areas. Finally, zooplankton provide food for numerous reef species, and indeed larvae from all species form part of the plankton temporarily too.