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1.
Background
Algal-cnidarian symbiosis is one of the main factors contributing to the success of cnidarians, and is crucial for the maintenance of coral reefs. While loss of the symbionts (such as in coral bleaching) may cause the death of the cnidarian host, over-proliferation of the algae may also harm the host. Thus, there is a need for the host to regulate the population density of its symbionts. In the green hydra, Chlorohydra viridissima, the density of symbiotic algae may be controlled through host modulation of the algal cell cycle. Alternatively, Chlorohydra may actively expel their endosymbionts, although this phenomenon has only been observed under experimentally contrived stress conditions.Principal Findings
We show, using light and electron microscopy, that Chlorohydra actively expel endosymbiotic algal cells during predatory feeding on Artemia. This expulsion occurs as part of the apocrine mode of secretion from the endodermal digestive cells, but may also occur via an independent exocytotic mechanism.Significance
Our results demonstrate, for the first time, active expulsion of endosymbiotic algae from cnidarians under natural conditions. We suggest this phenomenon may represent a mechanism whereby cnidarians can expel excess symbiotic algae when an alternative form of nutrition is available in the form of prey. 相似文献2.
3.
Background
Many coral reef organisms are photosynthetic or have evolved in tight symbiosis with photosynthetic symbionts. As such, the tissues of reef organisms are often exposed to intense solar radiation in clear tropical waters and have adapted to trap and harness photosynthetically active radiation (PAR). High levels of ultraviolet radiation (UVR) associated with sunlight, however, represent a potential problem in terms of tissue damage.Methodology/Principal Findings
By measuring UVR and PAR reflectance from intact and ground bare coral skeletons we show that the property of calcium carbonate skeletons to absorb downwelling UVR to a significant extent, while reflecting PAR back to the overlying tissue, has biological advantages. We placed cnidarians on top of bare skeletons and a UVR reflective substrate and showed that under ambient UVR levels, UVR transmitted through the tissues of cnidarians placed on top of bare skeletons were four times lower compared to their counterparts placed on a UVR reflective white substrate. In accordance with the lower levels of UVR measured in cnidarians on top of coral skeletons, a similar drop in UVR damage to their DNA was detected. The skeletons emitted absorbed UVR as yellow fluorescence, which allows for safe dissipation of the otherwise harmful radiation.Conclusions/Significance
Our study presents a novel defensive role for coral skeletons and reveals that the strong UVR absorbance by the skeleton can contribute to the ability of corals, and potentially other calcifiers, to thrive under UVR levels that are detrimental to most marine life. 相似文献4.
Brent A Knack Akira Iguchi Chuya Shinzato David C Hayward Eldon E Ball David J Miller 《BMC evolutionary biology》2008,8(1):136
Background
Adhesion mediated through the integrin family of cell surface receptors is central to early development throughout the Metazoa, playing key roles in cell-extra cellular matrix adhesion and modulation of cadherin activity during the convergence and extension movements of gastrulation. It has been suggested that Caenorhabditis elegans, which has a single β and two α integrins, might reflect the ancestral integrin complement. Investigation of the integrin repertoire of anthozoan cnidarians such as the coral Acropora millepora is required to test this hypothesis and may provide insights into the original roles of these molecules. 相似文献5.
The respiration rate of the Caribbean reef coral Porites porites was shown to increase by a mean of 39% above the pre-illumination respiration rate when exposed for 3 h to light equivalent to that at 10 m depth on the reef. When exposed to a subsaturating irradiance of 140 E m-2 s-1, the respiration rate increased successively in a curvilinear form to 58% greater than the preillumination respiration rate after 80 min. It is suggested that this increase may be analogous to the elevation in respiration rate observed in cnidarians and other animals after feeding on particulate food and may represent energy expenditure in growth. If this elevated respiration rate is maintained over the whole of the daytime period, the current methodologies used for determining carbon and energy budgets in symbiotic cnidarians result in an underestimation of the 24 h energy expenditure. 相似文献
6.
Hideyuki Yamashiro Hirosuke Oku Hideki Higa Isao Chinen Kazuhiko Sakai 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》1999,122(4):32
A survey of lipid composition was made for 15 cnidarians from Okinawa, Japan. Eleven zooxanthellate scleractinian corals, an azooxanthellate scleractinian coral Tubastrea sp., a soft coral Lobophytum crassum, a hydroid coral Millepora murrayi and a sea anemone Boloceroides sp. were examined to elucidate the total lipid content, fatty acid composition for each lipid class and sterol composition. All specimens contained monoalkyldiacylglycerol which migrated between the triacylglycerols and esters on thin layer chromatography (TLC). Analysis by high performance thin layer chromatography (HPTLC) and Gas chromatography-mass spectrometry (GC-MS) revealed that these cnidarians were rich in wax ester and triacylglycerol, and that palmitic acid (16:0) was the most abundant fatty acid component of these lipid classes, followed by stearic (18:0) and oleic (18:1, n-9) acid in order of concentration. Of 11 sterols separated, four sterols were identified. It is suggested that sterol composition may be more useful for the biochemical classification of these cnidarians than fatty acid composition. 相似文献
7.
Alejandro Reyes-Bermudez Zhiyi Lin David C Hayward David J Miller Eldon E Ball 《BMC evolutionary biology》2009,9(1):178-12
Background
The coral skeleton consists of CaCO3 deposited upon an organic matrix primarily as aragonite. Currently galaxin, from Galaxea fascicularis, is the only soluble protein component of the organic matrix that has been characterized from a coral. Three genes related to galaxin were identified in the coral Acropora millepora. 相似文献8.
Benyamin Rosental Zhanna Kozhekbaeva Nathaniel Fernhoff Jonathan M. Tsai Nikki Traylor-Knowles 《BMC cell biology》2017,18(1):30
Background
Generalized methods for understanding the cell biology of non-model species are quite rare, yet very much needed. In order to address this issue, we have modified a technique traditionally used in the biomedical field for ecological and evolutionary research. Fluorescent activated cell sorting (FACS) is often used for sorting and identifying cell populations. In this study, we developed a method to identify and isolate different cell populations in corals and other cnidarians.Methods
Using fluorescence-activated cell sorting (FACS), coral cell suspension were sorted into different cellular populations using fluorescent cell markers that are non-species specific. Over 30 different cell markers were tested. Additionally, cell suspension from Aiptasia pallida was also tested, and a phagocytosis test was done as a downstream functional assay.Results
We found that 24 of the screened markers positively labeled coral cells and 16 differentiated cell sub-populations. We identified 12 different cellular sub-populations using three markers, and found that each sub-population is primarily homogeneous. Lastly, we verified this technique in a sea anemone, Aiptasia pallida, and found that with minor modifications, a similar gating strategy can be successfully applied. Additionally, within A. pallida, we show elevated phagocytosis of sorted cells based on an immune associated marker.Conclusions
In this study, we successfully adapted FACS for isolating coral cell populations and conclude that this technique is translatable for future use in other species. This technique has the potential to be used for different types of studies on the cellular stress response and other immunological studies.9.
Background
Nitric oxide synthase (NOS) is an enzyme catalysing the conversion of L-arginine to L-citrulline and nitric oxide (NO), the latter being an essential messenger molecule for a range of biological processes. Whilst its role in higher vertebrates is well understood little is known about the role of this enzyme in early metazoan groups. For instance, NOS-mediated signalling has been associated with Cnidaria-algal symbioses, however controversy remains about the contribution of enzyme activities by the individual partners of these mutualistic relationships.Methodology/Principal Findings
Using a modified citrulline assay we successfully measured NOS activity in three cnidarian-algal symbioses: the sea anemone Aiptasia pallida, the hard coral Acropora millepora, and the soft coral Lobophytum pauciflorum, so demonstrating a wide distribution of this enzyme in the phylum Cnidaria. Further biochemical (citrulline assay) and histochemical (NADPH-diaphorase) investigations of NOS in the host tissue of L. pauciflorum revealed the cytosolic and calcium dependent nature of this enzyme and its in situ localisation within the coral''s gastrodermal tissue, the innermost layer of the body wall bearing the symbiotic algae. Interestingly, enzyme activity could not be detected in symbionts freshly isolated from the cnidarians, or in cultured algal symbionts.Conclusions/Significance
These results suggest that NOS-mediated NO release may be host-derived, a finding that has the potential to further refine our understanding of signalling events in cnidarian-algal symbioses. 相似文献10.
Nathaniel M Evans Alberto Lindner Ekaterina V Raikova Allen G Collins Paulyn Cartwright 《BMC evolutionary biology》2008,8(1):139
Background
Polypodium hydriforme is a parasite with an unusual life cycle and peculiar morphology, both of which have made its systematic position uncertain. Polypodium has traditionally been considered a cnidarian because it possesses nematocysts, the stinging structures characteristic of this phylum. However, recent molecular phylogenetic studies using 18S rDNA sequence data have challenged this interpretation, and have shown that Polypodium is a close relative to myxozoans and together they share a closer affinity to bilaterians than cnidarians. Due to the variable rates of 18S rDNA sequences, these results have been suggested to be an artifact of long-branch attraction (LBA). A recent study, using multiple protein coding markers, shows that the myxozoan Buddenbrockia, is nested within cnidarians. Polypodium was not included in this study. To further investigate the phylogenetic placement of Polypodium, we have performed phylogenetic analyses of metazoans with 18S and partial 28S rDNA sequences in a large dataset that includes Polypodium and a comprehensive sampling of cnidarian taxa. 相似文献11.
Oliver Selmoni Gaël Lecellier Véronique Berteaux-Lecellier Stéphane Joost 《Global Ecology and Biogeography》2023,32(5):622-632
Motivation
Host to intricate networks of marine species, coral reefs are among the most biologically diverse ecosystems on Earth. Over the past few decades, major degradations of coral reefs have been observed worldwide, which is largely attributed to the effects of climate change and local stressors related to human activities. Now more than ever, characterizing how the environment shapes the dynamics of the reef ecosystem (e.g., shifts in species abundance, community changes, emergence of locally adapted populations) is key to uncovering the environmental drivers of reef degradation, and developing efficient conservation strategies in response. To achieve these objectives, it is pivotal that environmental data describing the processes driving such ecosystem dynamics, which occur across specific spatial and temporal scales, are easily accessible to coral reef researchers and conservation stakeholders alike.Main types of variable contained
Multiple environmental variables characterizing various facets of the reef environment, including water chemistry and physics (e.g., temperature, pH, chlorophyll concentration), local anthropogenic pressures (e.g., boat traffic, distance from agricultural or urban areas) and sea currents patterns.Spatial location and grain
Worldwide reef cells of 5 by 5 km.Time period and grain
Last 3–4 decades, monthly and yearly resolution.Major taxa and level of measurement
Environmental data important for coral reefs and associated biodiversity.Software format
Interactive web application available at https://recifs.epfl.ch . 相似文献12.
Kinya Yasui James D. Reimer Yunhuan Liu Xiaoyong Yao Daisuke Kubo Degan Shu Yong Li 《PloS one》2013,8(6)
Background
Microfossils of the genus Punctatus include developmental stages such as blastula, gastrula, and hatchlings, and represent the most complete developmental sequence of animals available from the earliest Cambrian. Despite the extremely well-preserved specimens, the evolutionary position of Punctatus has relied only on their conical remains and they have been tentatively assigned to cnidarians. We present a new interpretation of the Punctatus body plan based on the developmental reconstruction aided by recent advances in developmental biology.Results
Punctatus developed from a rather large egg, gastrulated in a mode of invagination from a coeloblastura, and then formed a mouth directly from the blastopore. Spiny benthic hatchlings were distinguishable from swimming or crawling ciliate larvae found in cnidarians and sponges. A mouth appeared at the perihatching embryonic stage and was renewed periodically during growth, and old mouths transformed into the body wall, thus elongating the body. Growing animals retained a small blind gut in a large body cavity without partitioning by septa and did not form tentacles, pedal discs or holdfasts externally. A growth center at the oral pole was sufficient for body patterning throughout life, and the body patterning did not show any bias from radial symmetry.Conclusions
Contrary to proposed cnidarian affinity, the Punctatus body plan has basic differences from that of cnidarians, especially concerning a spacious body cavity separating ectoderm from endoderm. The lack of many basic cnidarian characters in the body patterning of Punctatus leads us to consider its own taxonomic group, potentially outside of Cnidaria. 相似文献13.
Catherine E. Sheppard Gareth J. Williams Dan A. Exton Sally A. Keith 《Global Ecology and Biogeography》2023,32(3):435-449
Aim
Biodiversity loss is impacting essential ecosystem functions and services across the globe. Recently, our interest in the benefits of biodiversity for ecosystem function has shifted focus from measurements of species richness to functional diversity and composition. However, the additional importance of other community characteristics, such as species evenness and co-occurrence, for diversity-driven ecosystem function is less known. We used herbivorous coral reef fish as a model system to investigate how co-occurrence of different functional groups, rather than purely functional diversity, within an assemblage might affect the coral reef benthic state.Location
Western Atlantic.Time period
2007–2017.Major taxa studied
Herbivorous reef fish.Methods
We analysed benthic and fish assemblage data from 601 sites across 12 countries in the western Atlantic. Using diversity–interaction models, we investigated how the composition and relative abundances of reef fish functional groups were correlated with benthic cover and estimates of coral calcification rates. We used statistical interactions to explore the importance of co-occurrence of herbivorous fish functional groups for the coral reef benthic state.Results
We found that co-occurrence of herbivorous fish functional groups, in addition to functional diversity, was correlated with reduced algal cover and increased coral accretion. Moreover, pairwise statistical interactions between functional groups were significantly correlated with an improvement in the coral reef benthic state.Main conclusions
Our results support the idea that functional group co-occurrence, in addition to functional diversity, within herbivorous fish offers additional benefits to the coral reef benthic state. We identify farming damselfish and excavating parrotfish as potential key determinants of the coral reef benthic state and highlight that co-occurrence of cropping and scraping herbivores might promote coral accretion. Our findings support the argument that protecting herbivore abundance without regard to the species and functional groups present is not enough to preserve coral reef health and that fine-scale community composition must be considered. 相似文献14.
15.
Félix Landry Yuan Takehisa Yamakita Timothy C. Bonebrake Shelby E. McIlroy 《Diversity & distributions》2023,29(11):1388-1401
Aim
The capacity for poleward range expansions beyond the tropics in corals hinges on ecophysiological constraints and resulting responses to climatic variability. We aimed to determine how future warming will affect coral habitat suitability at the poleward range edges of these foundational species in the Northwest Pacific.Location
Northwest Pacific.Methods
We generated models integrating thermal physiological constraints of corals adapted to extreme seasonality in Hong Kong, specifically the minimum annual temperature and the proportion of time annually spent at seasonal extremes. With these models, we projected habitat suitability for five coral species under current and future climatic conditions across the Northwest Pacific.Results
Climate model projections reveal an easing of thermal constraints on the leading-edge of coral ecophysiological limits with an expansion of thermally suitable habitat poleward by 2°–7° in latitude depending on the coral species and model considered. We also highlight a potential divergence of present and future thermal regimes that may lead to a mismatch in suitability for corals currently inhabiting high latitude reefs.Main Conclusions
Understanding the thermal constraints on coral distributions and defining the potential range of corals under climate change is critical for adaptive management that focuses on coral conservation and ensuring ecosystem function of existing subtropical and temperate ecosystems. 相似文献16.
17.
High diversity and host specificity observed among symbiotic dinoflagellates in reef coral communities from Hawaii 总被引:11,自引:0,他引:11
Todd C. LaJeunesse Daniel J. Thornhill Evelyn F. Cox Frank G. Stanton William K. Fitt Gregory W. Schmidt 《Coral reefs (Online)》2004,23(4):596-603
The Hawaiian Islands represent one of the most geographically remote locations in the Indo-Pacific, and are a refuge for rare, endemic life. The diversity of symbiotic dinoflagellates (Symbiodinium sp.) inhabiting zooxanthellate corals and other symbiotic cnidarians from the High Islands region was surveyed. From the 18 host genera examined, there were 20 genetically distinct symbiont types (17 in clade C, 1 in clade A, 1 in clade B, and 1 in clade D) distinguished by internal transcribed spacer region 2 sequences. Most types were found to associate with a particular host genus or species and nearly half of them have not been identified in surveys of Western and Eastern Pacific hosts. A clear dominant generalist symbiont is lacking among Hawaiian cnidarians. This is in marked contrast with the symbiont community structures of the western Pacific and Caribbean, which are dominated by a few prevalent generalist symbionts inhabiting numerous host taxa. Geographic isolation, low host diversity, and a high proportion of coral species that directly transmit their symbionts from generation to generation are implicated in the formation of a coral reef community exhibiting high symbiont diversity and specificity.Communicated by H.R. Lasker 相似文献
18.
Nataly Gutierrez-Isaza Eugenia M. Sampayo Catherine E. Lovelock Steven J. Dalton Carrie A. Sims Selina Ward John M. Pandolfi 《Global Ecology and Biogeography》2023,32(3):421-434
Aim
The aims were to test the role of temperature in latitudinal patterns of egg size and investigate maternal investment trade-offs among coral taxa.Location
Global, from 34° S to 34° N.Time period
1981–2020.Major taxa studied
Reef coral species from the order Scleractinia.Methods
We compiled a comprehensive geo-referenced global dataset of egg sizes (diameter or volume) and fecundity (number of eggs per area) for colonial corals (Scleractinia; 123 species, 5359 observations and 39 localities), substantially enhanced by new field collections (>88% of observations). We used Bayesian phylogenetic multilevel models to test for Rass' rule (a hypothesized negative relationship between egg size and temperature); we also included other environmental variables and life history traits. We also tested whether a trade-off exists between egg size and fecundity in broadcast spawning hermaphroditic corals with horizontal symbiont transmission (HHT).Results
We found a significant relationship between coral egg size and symbiont transmission. Eggs from coral species with vertical symbiont transmission were c. 18.8% smaller than those from species with horizontal symbiont transmission. We also found non-significant relationships between egg size and sea surface temperature (SST) for broadcast spawning corals and between egg size and fecundity specifically for HHT species.Main conclusions
Contrary to recognized latitudinal patterns of egg size across taxa, our study does not provide support for Rass' rule in corals. Additionally, our findings do not support a maternal investment trade-off between egg size and fecundity for HHT species. Our study used a phylogenetic framework that should be a standard practice when studying interspecific variation, including investigation of maternal investment and identification of the influence of multiple predictors on larval fitness (egg size), in addition to trade-offs affecting propagule influx (fecundity). Both these functional traits are vital and have direct consequences for population maintenance and connectivity in sessile organisms, such as corals. 相似文献19.
Vibrio Zinc-Metalloprotease Causes Photoinactivation of Coral Endosymbionts and Coral Tissue Lesions
Meir Sussman Jos C. Mieog Jason Doyle Steven Victor Bette L. Willis David G. Bourne 《PloS one》2009,4(2)
Background
Coral diseases are emerging as a serious threat to coral reefs worldwide. Of nine coral infectious diseases, whose pathogens have been characterized, six are caused by agents from the family Vibrionacae, raising questions as to their origin and role in coral disease aetiology.Methodology/Principal Findings
Here we report on a Vibrio zinc-metalloprotease causing rapid photoinactivation of susceptible Symbiodinium endosymbionts followed by lesions in coral tissue. Symbiodinium photosystem II inactivation was diagnosed by an imaging pulse amplitude modulation fluorometer in two bioassays, performed by exposing Symbiodinium cells and coral juveniles to non-inhibited and EDTA-inhibited supernatants derived from coral white syndrome pathogens.Conclusion/Significance
These findings demonstrate a common virulence factor from four phylogenetically related coral pathogens, suggesting that zinc-metalloproteases may play an important role in Vibrio pathogenicity in scleractinian corals. 相似文献20.