| 1. |
- Dylus, D.V., et al.
(författare)
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Large-scale gene expression study in the ophiuroid Amphiura filiformis provides insights into evolution of gene regulatory networks
- 2016
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Ingår i: EvoDevo. - : Springer Science and Business Media LLC. - 2041-9139. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- © 2016 Dylus et al. Background: The evolutionary mechanisms involved in shaping complex gene regulatory networks (GRN) that encode for morphologically similar structures in distantly related animals remain elusive. In this context, echinoderm larval skeletons found in brittle stars and sea urchins provide an ideal system. Here, we characterize for the first time the development of the larval skeleton in the ophiuroid Amphiura filiformis and compare it systematically with its counterpart in sea urchin. Results: We show that ophiuroids and euechinoids, that split at least 480 Million years ago (Mya), have remarkable similarities in tempo and mode of skeletal development. Despite morphological and ontological similarities, our high-resolution study of the dynamics of genetic regulatory states in A. filiformis highlights numerous differences in the architecture of their underlying GRNs. Importantly, the A.filiformis pplx, the closest gene to the sea urchin double negative gate (DNG) repressor pmar1, fails to drive the skeletogenic program in sea urchin, showing important evolutionary differences in protein function. hesC, the second repressor of the DNG, is co-expressed with most of the genes that are repressed in sea urchin, indicating the absence of direct repression of tbr, ets1/2, and delta in A. filiformis. Furthermore, the absence of expression in later stages of brittle star skeleton development of key regulatory genes, such as foxb and dri, shows significantly different regulatory states. Conclusion: Our data fill up an important gap in the picture of larval mesoderm in echinoderms and allows us to explore the evolutionary implications relative to the recently established phylogeny of echinoderm classes. In light of recent studies on other echinoderms, our data highlight a high evolutionary plasticity of the same nodes throughout evolution of echinoderm skeletogenesis. Finally, gene duplication, protein function diversification, and cis-regulatory element evolution all contributed to shape the regulatory program for larval skeletogenesis in different branches of echinoderms.
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| 2. |
- Georgian, Samuel E., et al.
(författare)
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Biogeographic variability in the physiological response of the cold-water coral Lophelia pertusa to ocean acidification
- 2016
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Ingår i: Marine Ecology. - : Wiley. - 0173-9565 .- 1439-0485. ; 37:6
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Tidskriftsartikel (refereegranskat)abstract
- While ocean acidification is a global issue, the severity of ecosystem effects is likely to vary considerably at regional scales. The lack of understanding of how biogeographically separated populations will respond to acidification hampers our ability to predict the future of vital ecosystems. Cold-water corals are important drivers of biodiversity in ocean basins across the world and are considered one of the most vulnerable ecosystems to ocean acidification. We tested the short-term physiological response of the cold-water coral Lophelia pertusa to three pH treatments (pH = 7.9, 7.75 and 7.6) for Gulf of Mexico (USA) and Tisler Reef (Norway) populations, and found that reductions in seawater pH elicited contrasting responses. Gulf of Mexico corals exhibited reductions in net calcification, respiration and prey capture rates with decreasing pH. In contrast, Tisler Reef corals showed only slight reductions in net calcification rates under decreased pH conditions while significantly elevating respiration and capture rates. These differences are likely the result of environmental differences (depth, pH, food supply) between the two regions, invoking the potential for local adaptation or acclimatization to alter their response to global change. However, it is also possible that variations in the methodology used in the experiments contributed to the observed differences. Regardless, these results provide insights into the resilience of L. pertusa to ocean acidification as well as the potential influence of regional differences on the viability of species in future oceans.
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| 3. |
- Hernroth, Bodil, 1951-, et al.
(författare)
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Immune suppression of the echinoderm Asterias rubens (L.) following long-term ocean acidification
- 2011
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Ingår i: Aquatic Toxicology. - 0166-445X .- 1879-1514. ; 103:3-4, s. 222-224
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Tidskriftsartikel (refereegranskat)abstract
- We compared effects of exposure to predict near-future (2100) ocean acidification (OA; pH 7.7) and normal seawater (Control; pH 8.1) on immune and stress responses in the adult sea star Asterias rubens. Analyses were made after one week and after six months of continuous exposure. Following one week exposure to acidified water, the pH of coelomic fluid was significantly reduced. Levels of the chaperon Hsp70 were elevated while key cellular players in immunity, coelomocytes. were reduced by approximately 50%. Following long-term exposure (six months) levels of Hsp70 returned to control values, whereas immunity was further impaired, evidenced by the reduced phagocytic capacity of coelomocytes and inhibited activation of p38 MAP-kinase. Such impacts of reduced seawater pH may have serious consequences for resistance to pathogens in a future acidified ocean.
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| 4. |
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| 5. |
- Hernroth, Bodil, 1951, et al.
(författare)
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Possibility of Mixed Progenitor Cells in Sea Star Arm Regeneration
- 2010
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Ingår i: Journal of Experimental Zoology Part B-Molecular and Developmental Evolution. - : Wiley. - 1552-5007 .- 1552-5015. ; 314B:6, s. 457-468
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Tidskriftsartikel (refereegranskat)abstract
- In contrast to most vertebrates, invertebrate deuterostome echinoderms, such as the sea star Asterias rubens, undergo regeneration of lost body parts. The current hypothesis suggests that differentiated cells are the main source for regenerating arm in sea stars, but there is little information regarding the origin and identity of these cells. Here, we show that several organs distant to the regenerating arm responded by proliferation, most significantly in the coelomic epithelium and larger cells of the pyloric caeca. Analyzing markers for proliferating cells and parameters indicating cell ageing, such as levels of DNA damage, pigment, and lipofuscin contents as well as telomere length and telomerase activity, we suggest that cells contributing to the new arm likely originate from progenitors rather than differentiated cells. This is the first study showing that cells of mixed origin may be recruited from more distant sources of stem/progenitor cells in a sea star, and the first described indication of a role for pyloric caeca in arm regeneration. Data on growth rate during arm regeneration further indicate that regeneration is at the expense of whole animal growth. We propose a new working hypothesis for arm regeneration in sea stars involving four phases: wound healing by coelomocytes, migration of distant progenitor cells of mixed origin including from pyloric caeca, proliferation in these organs to compensate for cell loss, and finally, local proliferation in the regenerating arm J. Exp. Zool. (Mol. Dev. Evol.) 3148:457-468, 2010. (C) 2010 Wiley-Liss, Inc.
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| 6. |
- Jagers, Sverker C., 1967, et al.
(författare)
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On the preconditions for large-scale collective action
- 2020
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 49:7
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Tidskriftsartikel (refereegranskat)abstract
- The phenomenon of collective action and the origin of collective action problems have been extensively and systematically studied in the social sciences. Yet, while we have substantial knowledge about the factors promoting collective action at the local level, we know far less about how these insights travel to large-scale collective action problems. Such problems, however, are at the heart of humanity's most pressing challenges, including climate change, large-scale natural resource depletion, biodiversity loss, nuclear proliferation, antibiotic resistance due to overconsumption of antibiotics, and pollution. In this paper, we suggest an analytical framework that captures the theoretical understanding of preconditions for large-scale collective action. This analytical framework aims at supporting future empirical analyses of how to cope with and overcome larger-scale collective action problems. More specifically, we (i) define and describe the main characteristics of a large-scale collective action problem and (ii) explain why voluntary and, in particular, spontaneous large-scale collective action among individual actors becomes more improbable as the collective action problem becomes larger, thus demanding interventions by an external authority (a third party) for such action to be generated. Based on this, we (iii) outline an analytical framework that illustrates the connection between third-party interventions and large-scale collective action. We conclude by suggesting avenues for future research.
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| 7. |
- Perry, D, et al.
(författare)
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Global environmental changes negatively impact temperate seagrass ecosystems
- 2019
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Ingår i: Ecosphere. - : Wiley. - 2150-8925. ; 10:12, s. 1-18
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Tidskriftsartikel (refereegranskat)abstract
- The oceans are increasingly affected by multiple aspects of global change, with substantial impacts on ecosystem functioning and food-web dynamics. While the effects of single factors have been extensively studied, it has become increasingly evident that there is a need to unravel the complexities related to a multiple stressor environment. In a mesocosm experimental study, we exposed a simplified, multi-trophic seagrass ecosystem (composed of seagrass, two shrimp species, and two intermediate predatory fish species) to three global change factors consisting of simulated storm events (Storms), heat shocks (Heat), and ocean acidification (OA), and the combination of all three factors (All). The most striking result indicated that when all factors were combined, there was a negative influence at all trophic levels, while the treatments with individual factors revealed species-specific response patterns. It appeared, however, that single factors may drive the multi-stressor response. All single factors (i.e., Storms, Heat, and OA) had either negative, neutral, or positive effects on fish and shrimp, whereas no effect was recorded for any single stressor on seagrass plants. The findings demonstrate that when several global change factors appear simultaneously, they can have deleterious impacts on seagrass ecosystems, and that the nature of factors and food-web composition may determine the sensitivity level of the system. In a global change scenario, this may have serious and applicable implications for the future of temperate seagrass ecosystems.
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| 8. |
- Ramachandra, Rashmi, et al.
(författare)
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A Potential Role for Chondroitin Sulfate/Dermatan Sulfate in Arm Regeneration in Amphiura filiformis.
- 2017
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 27:5, s. 438-449
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Tidskriftsartikel (refereegranskat)abstract
- Glycosaminoglycans (GAGs), such as chondroitin sulfate (CS) and dermatan sulfate (DS) from various vertebrate and invertebrate sources are known to be involved in diverse cellular mechanisms during repair and regenerative processes. Recently, we have identified CS/DS as the major GAG in the brittlestar Amphiura filiformis, with high proportions of di- and tri-O-sulfated disaccharide units. As this echinoderm is known for its exceptional regeneration capacity, we aimed to explore the role of these GAG chains during A. filiformis arm regeneration. Analysis of CS/DS chains during the regeneration process revealed an increase in the proportion of the tri-O-sulfated disaccharides. Conversely, treatment of A. filiformis with sodium chlorate, a potent inhibitor of sulfation reactions in GAG biosynthesis, resulted in a significant reduction in arm growth rates with total inhibition at concentrations higher than 5 mM. Differentiation was less impacted by sodium chlorate exposure or even slightly increased at 1-2 mM. Based on the structural changes observed during arm regeneration we identified chondroitin synthase, chondroitin-4-O-sulfotransferase 2 and dermatan-4-O-sulfotransferase as candidate genes and sought to correlate their expression with the expression of the A. filiformis orthologue of bone morphogenetic factors, AfBMP2/4. Quantitative amplification by real-time PCR indicated increased expression of chondroitin synthase and chondroitin-4-O-sulfotransferase 2, with a corresponding increase in AfBMP2/4 during regeneration relative to nonregenerating controls. Our findings suggest that proper sulfation of GAGs is important for A. filiformis arm regeneration and that these molecules may participate in mechanisms controlling cell proliferation.
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| 9. |
- Arnberg, M., et al.
(författare)
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Effects of oil and global environmental drivers on two keystone marine invertebrates
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Ocean warming (OW) and acidification (OA) are key features of global change and are predicted to have negative consequences for marine species and ecosystems. At a smaller scale increasing oil and gas activities at northern high latitudes could lead to greater risk of petroleum pollution, potentially exacerbating the effects of such global stressors. However, knowledge of combined effects is limited. This study employed a scenario-based, collapsed design to investigate the impact of one local acute stressor (North Sea crude oil) and two chronic global drivers (pH for OA and temperature for OW), alone or in combination on aspects of the biology of larval stages of two key invertebrates: the northern shrimp (Pandalus borealis) and the green sea urchin (Strongylocentrotus droebachiensis). Both local and global drivers had negative effects on survival, development and growth of the larval stages. These effects were species- and stage-dependent. No statistical interactions were observed between local and global drivers and the combined effects of the two drivers were approximately equal to the sum of their separate effects. This study highlights the importance of adjusting regulation associated with oil spill prevention to maximize the resilience of marine organisms to predicted future global conditions. © 2018, The Author(s).
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| 10. |
- Bach, Lennart T, et al.
(författare)
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Influence of Ocean Acidification on a Natural Winter-to-Summer Plankton Succession: First Insights from a Long-Term Mesocosm Study Draw Attention to Periods of Low Nutrient Concentrations
- 2016
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- Every year, the oceans absorb about 30% of anthropogenic carbon dioxide (CO2) leading to a re-equilibration of the marine carbonate system and decreasing seawater pH. Today, there is increasing awareness that these changes-summarized by the term ocean acidification (OA)-could differentially affect the competitive ability of marine organisms, thereby provoking a restructuring of marine ecosystems and biogeochemical element cycles. In winter 2013, we deployed ten pelagic mesocosms in the Gullmar Fjord at the Swedish west coast in order to study the effect of OA on plankton ecology and biogeochemistry under close to natural conditions. Five of the ten mesocosms were left unperturbed and served as controls (similar to 380 mu atm pCO(2)), whereas the others were enriched with CO2-saturated water to simulate realistic end-of-the-century carbonate chemistry conditions (mu 760 mu atm pCO(2)). We ran the experiment for 113 days which allowed us to study the influence of high CO2 on an entire winter-to-summer plankton succession and to investigate the potential of some plankton organisms for evolutionary adaptation to OA in their natural environment. This paper is the first in a PLOS collection and provides a detailed overview on the experimental design, important events, and the key complexities of such a "long-term mesocosm" approach. Furthermore, we analyzed whether simulated end-of-the-century carbonate chemistry conditions could lead to a significant restructuring of the plankton community in the course of the succession. At the level of detail analyzed in this overview paper we found that CO2-induced differences in plankton community composition were non-detectable during most of the succession except for a period where a phytoplankton bloom was fueled by remineralized nutrients. These results indicate: (1) Long-term studies with pelagic ecosystems are necessary to uncover OA-sensitive stages of succession. (2) Plankton communities fueled by regenerated nutrients may be more responsive to changing carbonate chemistry than those having access to high inorganic nutrient concentrations and may deserve particular attention in future studies.
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