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- 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. |
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| 3. |
- 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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| 4. |
- 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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