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Gerhard Jarms - One of the best experts on this subject based on the ideXlab platform.
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Effects of low salinity on settlement and strobilation of scyphozoa (Cnidaria): Is the lion’s mane Cyanea capillata (L.) able to reproduce in the brackish Baltic Sea?
Hydrobiologia, 2010Co-Authors: Sabine Holst, Gerhard JarmsAbstract:Several species of scyphozoan medusae occur in river estuaries and other brackish waters but it is often unknown if the Planulae settle and the scyphopolyps reproduce in those low-salinity waters. In the present study, scyphozoan species from the German Bight (North Sea) were tested in laboratory experiments to investigate their tolerance of low salinity. Planula larvae released from medusae in salinity 32 were still active after the salinity was reduced to 10 ( Cyanea capillata , Cyanea lamarckii ) and to 7 ( Chrysaora hysoscella ) in laboratory treatments. Planulae did not settle on the undersides of floating substrates when salinity was reduced to
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effects of low salinity on settlement and strobilation of scyphozoa cnidaria is the lion s mane cyanea capillata l able to reproduce in the brackish baltic sea
Hydrobiologia, 2010Co-Authors: Sabine Holst, Gerhard JarmsAbstract:Several species of scyphozoan medusae occur in river estuaries and other brackish waters but it is often unknown if the Planulae settle and the scyphopolyps reproduce in those low-salinity waters. In the present study, scyphozoan species from the German Bight (North Sea) were tested in laboratory experiments to investigate their tolerance of low salinity. Planula larvae released from medusae in salinity 32 were still active after the salinity was reduced to 10 (Cyanea capillata, Cyanea lamarckii) and to 7 (Chrysaora hysoscella) in laboratory treatments. Planulae did not settle on the undersides of floating substrates when salinity was reduced to <20. By contrast, Planulae released from C. capillata medusae in Kiel Bight (western Baltic Sea) in salinity 15 developed into polyps in laboratory cultures. Polyps reared from Planulae in salinity 36 survived a reduction to 12 (C. capillata, C. lamarckii) and to 8 (Aurelia aurita). Polyps of all tested species strobilated and released young medusae (ephyrae) in salinity 12. These results show a high tolerance of Planulae and polyps to low salinity, indicating their possible occurrence in estuaries and brackish waters. In addition to laboratory observations, young C. capillata ephyrae were collected in the western Baltic Sea (Kiel Bight) in salinity 15, which indicates that they were probably released by a local polyp population. We suggest that the polyps of the painfully stinging lion’s mane, C. capillata, may be more widespread in the Baltic Sea than previously assumed and that the occurrence of the medusae may not only depend on inflow of water masses from the North Sea.
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life cycle of the rhizostome jellyfish rhizostoma octopus l scyphozoa rhizostomeae with studies on cnidocysts and statoliths
Marine Biology, 2007Co-Authors: Sabine Holst, Ilka Sotje, Henry Tiemann, Gerhard JarmsAbstract:Stages in the life cycle of the rhizostome jellyfish Rhizostoma octopus (L.) were reared in the laboratory from Planula to young medusa and are described here. Fertilization of eggs was external, and Planulae, 110–150 μm in length, appeared after 2 days. These settled and developed into the scyphistoma stage. Scyphistomae reached a maximum size of 2.3 mm, bore up to 24 tentacles, and had a large manubrium. Polyps reproduced asexually mainly by podocysts. Strobilation was induced by temperature change. Each strobila released up to five ephyrae that measured 2.7–5.8 mm in diameter at liberation. During transformation from newly released ephyra to young medusa, velar lappets appeared and increased in number, the manubrium developed eight branched oral arms with epaulettes, and a marginal gastric network arose. Only one cnidocyst type, the “a”-atrichous haploneme, was present in the Planula. In addition to these haplonemes, heterotrichous microbasic euryteles were observed in polyps, ephyrae, and medusae. Statoliths, located in the rhopalia, had a characteristic compact shape. These sensory structures increased in number and size with the growth of ephyrae and medusae.
Tamar Lotan - One of the best experts on this subject based on the ideXlab platform.
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Signaling via GABAB receptors regulates early development and neurogenesis in the basal metazoan Nematostella vectensis
2019Co-Authors: Shani Levy, Vera Brekhman, Arnau Sebé-pedrós, Anna Bakhman, Mickey Kosloff, Tamar LotanAbstract:The metabotropic gamma-amino-butyric acid B receptor (GABA B R) is a G protein-coupled receptor that mediates neuronal inhibition by the neurotransmitter GABA. Here, we identified putative GABA B receptors and signaling modulators in the basal sea anemone Nematostella vectensis . Activation of GABA B R signaling reversibly arrests Planula-to-polyp transformation during early development and affects the neurogenic program. We identified four Nematostella GABA B R homologs that have the conserved 3D extracellular domains and residues needed for binding of GABA and the GABA B R agonist baclofen. Transcriptomic analysis, combined with spatial analysis of baclofen-treated Planulae, revealed that baclofen down-regulated pro-neural factors such as NvSoxB(2) , NvNeuroD1 and NvElav1 . Baclofen also inhibited neuron development and extended neurites, resulting in an under-developed and less organized nervous system. Our results shed light on cnidarian development and suggest an evolutionarily conserved function for GABA B R in regulation of neurogenesis, highlighting Nematostella as a new model system to study GABA B R signaling.
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Transcriptome profiling of the dynamic life cycle of the scypohozoan jellyfish Aurelia aurita
BMC Genomics, 2015Co-Authors: Vera Brekhman, Noa Sher, Brian Haas, Assaf Malik, Tamar LotanAbstract:BackgroundThe moon jellyfish Aurelia aurita is a widespread scyphozoan species that forms large seasonal blooms. Here we provide the first comprehensive view of the entire complex life of the Aurelia Red Sea strain by employing transcriptomic profiling of each stage from Planula to mature medusa.ResultsA de novo transcriptome was assembled from Illumina RNA-Seq data generated from six stages throughout the Aurelia life cycle. Transcript expression profiling yielded clusters of annotated transcripts with functions related to each specific life-cycle stage. Free-swimming Planulae were found highly enriched for functions related to cilia and microtubules, and the drastic morphogenetic process undergone by the Planula while establishing the future body of the polyp may be mediated by specifically expressed Wnt ligands. Specific transcripts related to sensory functions were found in the strobila and the ephyra, whereas extracellular matrix functions were enriched in the medusa due to high expression of transcripts such as collagen, fibrillin and laminin, presumably involved in mesoglea development. The CL390-like gene, suggested to act as a strobilation hormone, was also highly expressed in the advanced strobila of the Red Sea species, and in the medusa stage we identified betaine-homocysteine methyltransferase, an enzyme that may play an important part in maintaining equilibrium of the medusa’s bell. Finally, we identified the transcription factors participating in the Aurelia life-cycle and found that 70% of these 487 identified transcription factors were expressed in a developmental-stage-specific manner.ConclusionsThis study provides the first scyphozoan transcriptome covering the entire developmental trajectory of the life cycle of Aurelia. It highlights the importance of numerous stage-specific transcription factors in driving morphological and functional changes throughout this complex metamorphosis, and is expected to be a valuable resource to the community.
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transcriptome profiling of the dynamic life cycle of the scypohozoan jellyfish aurelia aurita
BMC Genomics, 2015Co-Authors: Vera Brekhman, Noa Sher, Assaf Malik, Brian J Haas, Tamar LotanAbstract:The moon jellyfish Aurelia aurita is a widespread scyphozoan species that forms large seasonal blooms. Here we provide the first comprehensive view of the entire complex life of the Aurelia Red Sea strain by employing transcriptomic profiling of each stage from Planula to mature medusa. A de novo transcriptome was assembled from Illumina RNA-Seq data generated from six stages throughout the Aurelia life cycle. Transcript expression profiling yielded clusters of annotated transcripts with functions related to each specific life-cycle stage. Free-swimming Planulae were found highly enriched for functions related to cilia and microtubules, and the drastic morphogenetic process undergone by the Planula while establishing the future body of the polyp may be mediated by specifically expressed Wnt ligands. Specific transcripts related to sensory functions were found in the strobila and the ephyra, whereas extracellular matrix functions were enriched in the medusa due to high expression of transcripts such as collagen, fibrillin and laminin, presumably involved in mesoglea development. The CL390-like gene, suggested to act as a strobilation hormone, was also highly expressed in the advanced strobila of the Red Sea species, and in the medusa stage we identified betaine-homocysteine methyltransferase, an enzyme that may play an important part in maintaining equilibrium of the medusa’s bell. Finally, we identified the transcription factors participating in the Aurelia life-cycle and found that 70% of these 487 identified transcription factors were expressed in a developmental-stage-specific manner. This study provides the first scyphozoan transcriptome covering the entire developmental trajectory of the life cycle of Aurelia. It highlights the importance of numerous stage-specific transcription factors in driving morphological and functional changes throughout this complex metamorphosis, and is expected to be a valuable resource to the community.
D. K. Hofmann - One of the best experts on this subject based on the ideXlab platform.
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The Effects of the UV-Blocker Oxybenzone (Benzophenone-3) on Planulae Swimming and Metamorphosis of the Scyphozoans Cassiopea xamachana and Cassiopea frondosa
Oceans, 2020Co-Authors: William K. Fitt, D. K. HofmannAbstract:Benzophenones are UV-blockers found in most common sunscreens. The ability of Scyphozoan Planula larvae of Cassiopea xamachana and C. frondosa to swim and complete metamorphosis in concentrations 0–228 µg/L benzophenone-3 (oxybenzone) was tested. Planulae of both species swam in erratic patterns, 25–30% slower, and experienced significant death (p < 0.05) in the highest concentrations of oxybenzone tested, whereas the larvae exhibited normal swimming patterns and no death in ≤2.28 µg/L oxybenzone. In addition, metamorphosis decreased 10–30% over 3 days for both species maintained in 228 µg/L oxybenzone. These effects do not involve symbiotic dinoflagellates, as Planulae larvae of Cassiopea sp. are aposymbiotic. It is concluded that oxybenzone can have a detrimental impact on these jellyfish.
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an endogenous peptide is involved in internal control of metamorphosis in the marine invertebrate cassiopea xamachana cnidaria scyphozoa
Development Genes and Evolution, 2003Co-Authors: C Thieme, D. K. HofmannAbstract:In the metagenetic life-cycle of the scyphozoan Cassiopea xamachana metamorphosis of Planula-larvae or larva-like buds to polyps is triggered by specific external cues which are transmitted inside the larva or bud where internal signals finally coordinate the initiation of metamorphosis. This study deals with an endogenous metamorphosis inducer present in Planulae and buds of Cassiopea. The inductive cue is localized in the basal part of the buds and can be characterized as a peptide with an apparent molecular weight of about 7,000 Da. Further purification was performed via reversed phase HPLC on a C18 column. Additional inhibitor assays revealed that protein kinase C and PI3 kinase, two known elements of the metamorphosis-inducing signal transduction cascade in Cassiopea, may act downstream of the endogenous inducing peptide.
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reproduction in the red sea soft coral heteroxenia fuscescens seasonality and long term record 1991 to 1997
Marine Biology, 1999Co-Authors: R Bendavidzaslow, D. K. Hofmann, G Henning, Yehuda BenayahuAbstract:Heteroxenia fuscescens is a common zooxanthellate soft coral on the shallow reefs in the Gulf of Eilat, northern Red Sea. In the Red Sea, during its prolonged Planulation, H. fuscescens is subjected to a seasonal environmental regime that alternates between stratified warm summer waters and upwelling of low-temperature winter waters. To examine the possible relationship between these seasonal fluctuations and the reproductive characteristics of H. fuscescens, we monitored its breeding activity for a 6-year period, including the percentage of colonies releasing Planulae, number of Planulae released per colony per night (fecundity), Planula size and percentage of released deformed Planulae. During summer and fall the combined average percentage of Planulating colonies of H. fuscescens was significantly higher than in winter and spring. In addition, fecundity was greater during the summer than the rest of the year. Planulae released during summer were longer, with almost zero percent deformation. During the rest of the year they were shorter, with a higher percentage of deformation. The current study indicates that although H. fuscescens reproduces all year round, the quantity and quality of its reproductive features are subject to seasonal variability. In the Gulf of Eilat seasonal changes in the abiotic features of the water may have an impact on its reproduction. During summer, primary productivity reaches a distinctive maximum up to a depth of about 40 m. The winter upwelling waters introduce nutrients from the depths into the upper 200 m, and especially into the major primary productivity zone, thereby triggering the annual phytoplankton bloom. Because colonies of H. fuscescens gain nutritional benefit from uptake of organic material dissolved in the water and by carbon fixation by zooxanthellae, we␣suggest that the seasonal fluctuations in the species' reproductive traits are related to these fluctuations in nutrient and light levels.
Yehuda Benayahu - One of the best experts on this subject based on the ideXlab platform.
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the effect of bacteria on Planula larvae settlement and metamorphosis in the octocoral rhytisma fulvum fulvum
PLOS ONE, 2019Co-Authors: Isabel Freire, Yehuda Benayahu, Eldad Gutnerhoch, Andrea Muras, Ana OteroAbstract:While increasing evidence supports a key role of bacteria in coral larvae settlement and development, the relative importance of environmentally-acquired versus vertically-transferred bacterial population is not clear. Here we have attempted to elucidate the role of post-brooding-acquired bacteria on the development of Planula-larvae of the octocoral Rhytisma f. fulvum, in an in vitro cultivation system employing different types of filtered (FSW) and autoclaved (ASW) seawater and with the addition of native bacteria. A good development of larvae was obtained in polystyrene 6-well cell culture plates in the absence of natural reef substrata, achieving a 60-80% of larvae entering metamorphosis after 32 days, even in bacteria-free seawater, indicating that the bacteria acquired during the brooding period are sufficient to support Planulae development. No significant difference in Planulae attachment and development was observed when using 0.45 μm or 0.22 μm FSW, although autoclaving the 0.45 μm FSW negatively affected larval development, indicating the presence of beneficial bacteria. Autoclaving the different FSW homogenized the development of the larvae among the different treatments. The addition of bacterial strains isolated from the different FSW did not cause any significant effect on Planulae development, although some specific strains of the genus Alteromonas seem to be beneficial for larvae development. Light was beneficial for Planulae development after day 20, although no Symbiodinium cells could be observed, indicating either that light acts as a positive cue for larval development or the presence of beneficial phototrophic bacteria in the coral microbiome. The feasibility of obtaining advanced metamorphosed larvae in sterilized water provides an invaluable tool for studying the physiological role of the bacterial symbionts in the coral holobiont and the specificity of bacteria-coral interactions.
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biochemical composition metabolism and amino acid transport in Planula larvae of the soft coral heteroxenia fuscescens
Journal of Experimental Zoology, 2000Co-Authors: Revital Bendavidzaslow, Yehuda BenayahuAbstract:We determined the monthly percentage of biochemical components in Planulae of the soft coral Heteroxenia fuscescens, for a 3-year period, and evaluated the findings in relation to seasonal fluctuations in water temperature. We determined the biochemical profile and metabolic rate of aging Planulae and examined the possible absorption of dissolved organic material (DOM) from the water by the Planulae. Our study is the first to present a long-term biochemical profile of Planulae. They contained an average of 2.2% ash, 51.5% lipid, 33.6% protein, and 1.3% carbohydrate. Calculation of the average energetic content of a Planula revealed a value of 1. 63 J Planula(-1). Significant seasonal differences in Planulae weight were noted between the summer and the other seasons. A significant decrease (41%) from the initial weight, 0.029 mg, took place in the Planulae dry weight within 15 days. Significant decreases over time were also found in lipid (50%) and carbohydrate (83%) concentration but not in protein (20%). Metabolic rates of a Planula was 0.06 microl O(2) Planula(-1) hr(-1). The study shows for the first time that a soft coral Planulae can take up dissolved free amino acids from seawater. Even though each of the amino acids was initially present at equimolar concentrations, there was a much faster uptake for the neutral, nonpolar amino acids, than for polar and basic ones. The potential contribution to the metabolic demand of Planulae, from the uptake of amino acids, is estimated to be 11%. It is suggested that this uptake does not appear to be due to energetic considerations, but may have a more significant impact on their nitrogen budget.
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reproduction in the red sea soft coral heteroxenia fuscescens seasonality and long term record 1991 to 1997
Marine Biology, 1999Co-Authors: R Bendavidzaslow, D. K. Hofmann, G Henning, Yehuda BenayahuAbstract:Heteroxenia fuscescens is a common zooxanthellate soft coral on the shallow reefs in the Gulf of Eilat, northern Red Sea. In the Red Sea, during its prolonged Planulation, H. fuscescens is subjected to a seasonal environmental regime that alternates between stratified warm summer waters and upwelling of low-temperature winter waters. To examine the possible relationship between these seasonal fluctuations and the reproductive characteristics of H. fuscescens, we monitored its breeding activity for a 6-year period, including the percentage of colonies releasing Planulae, number of Planulae released per colony per night (fecundity), Planula size and percentage of released deformed Planulae. During summer and fall the combined average percentage of Planulating colonies of H. fuscescens was significantly higher than in winter and spring. In addition, fecundity was greater during the summer than the rest of the year. Planulae released during summer were longer, with almost zero percent deformation. During the rest of the year they were shorter, with a higher percentage of deformation. The current study indicates that although H. fuscescens reproduces all year round, the quantity and quality of its reproductive features are subject to seasonal variability. In the Gulf of Eilat seasonal changes in the abiotic features of the water may have an impact on its reproduction. During summer, primary productivity reaches a distinctive maximum up to a depth of about 40 m. The winter upwelling waters introduce nutrients from the depths into the upper 200 m, and especially into the major primary productivity zone, thereby triggering the annual phytoplankton bloom. Because colonies of H. fuscescens gain nutritional benefit from uptake of organic material dissolved in the water and by carbon fixation by zooxanthellae, we␣suggest that the seasonal fluctuations in the species' reproductive traits are related to these fluctuations in nutrient and light levels.
Vera Brekhman - One of the best experts on this subject based on the ideXlab platform.
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Signaling via GABAB receptors regulates early development and neurogenesis in the basal metazoan Nematostella vectensis
2019Co-Authors: Shani Levy, Vera Brekhman, Arnau Sebé-pedrós, Anna Bakhman, Mickey Kosloff, Tamar LotanAbstract:The metabotropic gamma-amino-butyric acid B receptor (GABA B R) is a G protein-coupled receptor that mediates neuronal inhibition by the neurotransmitter GABA. Here, we identified putative GABA B receptors and signaling modulators in the basal sea anemone Nematostella vectensis . Activation of GABA B R signaling reversibly arrests Planula-to-polyp transformation during early development and affects the neurogenic program. We identified four Nematostella GABA B R homologs that have the conserved 3D extracellular domains and residues needed for binding of GABA and the GABA B R agonist baclofen. Transcriptomic analysis, combined with spatial analysis of baclofen-treated Planulae, revealed that baclofen down-regulated pro-neural factors such as NvSoxB(2) , NvNeuroD1 and NvElav1 . Baclofen also inhibited neuron development and extended neurites, resulting in an under-developed and less organized nervous system. Our results shed light on cnidarian development and suggest an evolutionarily conserved function for GABA B R in regulation of neurogenesis, highlighting Nematostella as a new model system to study GABA B R signaling.
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Transcriptome profiling of the dynamic life cycle of the scypohozoan jellyfish Aurelia aurita
BMC Genomics, 2015Co-Authors: Vera Brekhman, Noa Sher, Brian Haas, Assaf Malik, Tamar LotanAbstract:BackgroundThe moon jellyfish Aurelia aurita is a widespread scyphozoan species that forms large seasonal blooms. Here we provide the first comprehensive view of the entire complex life of the Aurelia Red Sea strain by employing transcriptomic profiling of each stage from Planula to mature medusa.ResultsA de novo transcriptome was assembled from Illumina RNA-Seq data generated from six stages throughout the Aurelia life cycle. Transcript expression profiling yielded clusters of annotated transcripts with functions related to each specific life-cycle stage. Free-swimming Planulae were found highly enriched for functions related to cilia and microtubules, and the drastic morphogenetic process undergone by the Planula while establishing the future body of the polyp may be mediated by specifically expressed Wnt ligands. Specific transcripts related to sensory functions were found in the strobila and the ephyra, whereas extracellular matrix functions were enriched in the medusa due to high expression of transcripts such as collagen, fibrillin and laminin, presumably involved in mesoglea development. The CL390-like gene, suggested to act as a strobilation hormone, was also highly expressed in the advanced strobila of the Red Sea species, and in the medusa stage we identified betaine-homocysteine methyltransferase, an enzyme that may play an important part in maintaining equilibrium of the medusa’s bell. Finally, we identified the transcription factors participating in the Aurelia life-cycle and found that 70% of these 487 identified transcription factors were expressed in a developmental-stage-specific manner.ConclusionsThis study provides the first scyphozoan transcriptome covering the entire developmental trajectory of the life cycle of Aurelia. It highlights the importance of numerous stage-specific transcription factors in driving morphological and functional changes throughout this complex metamorphosis, and is expected to be a valuable resource to the community.
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transcriptome profiling of the dynamic life cycle of the scypohozoan jellyfish aurelia aurita
BMC Genomics, 2015Co-Authors: Vera Brekhman, Noa Sher, Assaf Malik, Brian J Haas, Tamar LotanAbstract:The moon jellyfish Aurelia aurita is a widespread scyphozoan species that forms large seasonal blooms. Here we provide the first comprehensive view of the entire complex life of the Aurelia Red Sea strain by employing transcriptomic profiling of each stage from Planula to mature medusa. A de novo transcriptome was assembled from Illumina RNA-Seq data generated from six stages throughout the Aurelia life cycle. Transcript expression profiling yielded clusters of annotated transcripts with functions related to each specific life-cycle stage. Free-swimming Planulae were found highly enriched for functions related to cilia and microtubules, and the drastic morphogenetic process undergone by the Planula while establishing the future body of the polyp may be mediated by specifically expressed Wnt ligands. Specific transcripts related to sensory functions were found in the strobila and the ephyra, whereas extracellular matrix functions were enriched in the medusa due to high expression of transcripts such as collagen, fibrillin and laminin, presumably involved in mesoglea development. The CL390-like gene, suggested to act as a strobilation hormone, was also highly expressed in the advanced strobila of the Red Sea species, and in the medusa stage we identified betaine-homocysteine methyltransferase, an enzyme that may play an important part in maintaining equilibrium of the medusa’s bell. Finally, we identified the transcription factors participating in the Aurelia life-cycle and found that 70% of these 487 identified transcription factors were expressed in a developmental-stage-specific manner. This study provides the first scyphozoan transcriptome covering the entire developmental trajectory of the life cycle of Aurelia. It highlights the importance of numerous stage-specific transcription factors in driving morphological and functional changes throughout this complex metamorphosis, and is expected to be a valuable resource to the community.
