| 1. |
- Dylus, D.V., et al.
(författare)
-
Large-scale gene expression study in the ophiuroid Amphiura filiformis provides insights into evolution of gene regulatory networks
- 2016
-
Ingår i: EvoDevo. - : Springer Science and Business Media LLC. - 2041-9139. ; 7:1
-
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.
|
|
| 2. |
- Hernroth, Bodil, 1951-, et al.
(författare)
-
Immune suppression of the echinoderm Asterias rubens (L.) following long-term ocean acidification
- 2011
-
Ingår i: Aquatic Toxicology. - 0166-445X .- 1879-1514. ; 103:3-4, s. 222-224
-
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.
|
|
| 3. |
|
|
| 4. |
- Hernroth, Bodil, 1951, et al.
(författare)
-
Possibility of Mixed Progenitor Cells in Sea Star Arm Regeneration
- 2010
-
Ingår i: Journal of Experimental Zoology Part B-Molecular and Developmental Evolution. - : Wiley. - 1552-5007 .- 1552-5015. ; 314B:6, s. 457-468
-
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.
|
|
| 5. |
- Jagers, Sverker C., 1967, et al.
(författare)
-
On the preconditions for large-scale collective action
- 2020
-
Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 49:7, s. 1282-1296
-
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.
|
|
| 6. |
|
|
| 7. |
- Perry, D, et al.
(författare)
-
Global environmental changes negatively impact temperate seagrass ecosystems
- 2019
-
Ingår i: Ecosphere. - : Wiley. - 2150-8925. ; 10:12, s. 1-18
-
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.
|
|
| 8. |
- Ramachandra, Rashmi, et al.
(författare)
-
A Potential Role for Chondroitin Sulfate/Dermatan Sulfate in Arm Regeneration in Amphiura filiformis.
- 2017
-
Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 27:5, s. 438-449
-
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.
|
|
| 9. |
- Andersson, Pia, et al.
(författare)
-
Marine Acidification : On effects and monitoring of marine acidification in the seas surrounding Sweden
- 2008. - 2008:92
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Surface waters in the world oceans have already experienced a pH reduction of about 0.1 units (OSPAR, 2006.) The trend indicates further decrease of pH and is most probably due to increased uptake of atmospheric CO2 and less buffering capacity of ocean waters. The trend is similar in the waters surrounding Sweden. RESEARCH NEEDS Since there is an alarming absence of information regarding the effects of near-future levels of ocean acidification on Swedish marine taxa, there is a clear research need on: • investigations of the effects of ocean acidification on the early life-history stages of key ecosystem-structuring species, and commercially important species of fish and shellfish • ecosystem-level mesocosm studies of the impacts of ocean acidification on Swedish marine systems • improved regional-scale modelling of acidification mechanisms in Swedish coastal waters • testable ecosystem-scale food-web models to articulate with regional acidification models • improved definition of chemical equilibrium constants between pH, AT and CO2 in low saline waters. ACTIONS TO IMPROVE MONITORING At present, pH and AT are monitored monthly at standard depths at 7 stations in Skagerrak, Kattegat and Baltic Proper within the national monitoring programme. Of these are 2 located in coastal waters (Halland and Småland; Type 5 and 9). We recommend that Sweden work to improve the status of pH and AT to be Core variables instead of Main variables in HELCOM COMBINE “High frequency Sampling” program taking into account the last 15 years negative trends in pH in waters surrounding Sweden as well as in the global oceans. We recommend that besides the standard para-meters monitored in the national monitoring program, pH, AT and DIC should be monitored. For completeness, primary production should also be monitored. Below are three monitoring recommendations, where the first is divided into a lowest level and a recommended level. 1. Lowest level: Within the national monitoring program, at least one station per open sea area and all costal stations measure acidification parameters on a monthly basis in the entire water column at standardized depths. The national and regional monitoring programmes should be upgraded in the Gulf of Bothnia so that pH and AT is monitored at standard depths at least monthly at one station each in the Bothnian Bay and Bothnian Sea. Also 2 coastal stations in the Gulf of Bothnia should be established. In addition, one coastal station should be established within Type 14 in the Baltic Proper. 1. Recommended level: the national monitoring program should have at least one station per open sea area and if the area is characterized by strong gradients or other features, there should be more than one station. Some of the stations in the regional monitoring programmes should be upgraded with acidification parameters, for a better geographical coverage. The acidification parameters should be measured on a monthly basis in the entire water column at standardized depths. 2. We recommend that an investigative monitoring is established by extending the parameters that are needed to firmly improve the chemical stability constants between pH, AT, DIC and pCO2 in low saline waters. This can be done by just extending the sampling program at selected monitoring stations. Sampling should cover a period of 2 to 3 years. 3. We recommend that direct water measurement of pCO2 for monitoring purposes should be assessed after the recommendation above is evaluated and that ongoing research projects on pCO2 measurements using ferryboxes are finalised. RECOGNISED PROBLEM AREAS • There are only few long time series of acidification parameters. The time period of measurements is rather short. • The geographical coverage of measurements is rather limited in the waters surrounding Sweden. • The chemical stability constants between pH, AT, DIC and pCO2 are not optimized in low saline waters. • pH budgets are difficult to calculate. • Models need to be improved in order to display present and future small and large scale scenarios. • Little is known of the biological, ecological and economical effects of the current and near future marine acidification. Further research is required.
|
|
| 10. |
- Gustafsson, Erik, 1977-, et al.
(författare)
-
Havsförsurning ytterligare etthot mot Östersjöns ekosystem
- 2024
-
Annan publikation (populärvet., debatt m.m.)abstract
- Havsförsurningen väntas de kommande decennierna bli påtaglig även i Östersjön. För det redan hårt pressade ekosystemet innebär det ytterligare en belastning. Den samlade effekten av försurningen och annan miljöpåverkan kan stressa arter och minska den biologiska mångfalden. För att skydda den unika miljön och den framtida matproduktionen krävs både kraftigt minskade koldioxidutsläpp och åtgärder mot övergödning, överfiske och utsläpp av farliga ämnen.
|
|
