Project description:<p>As a well-known pseudo-persistent environmental pollutant, oxybenzone (BP-3) and its related organic ultraviolet (UV) filters have been verified to directly contribute to the increasing mortality rate of coral reefs. Previous studies have revealed the potential role of symbiotic Symbiodiniaceae in protecting corals from the toxic effects of UV filters. However, the detailed protection mechanism(s) have not been explained. Here, the impacts of BP-3 on the symbiotic Symbiodiniaceae <em>Cladocopium goreaui</em> were explored. <em>C. goreaui</em> cells exhibited distinct cell growth at different BP-3 doses, with increasing growth at the lower concentration (2 mg/L) and rapid death at a higher concentration (20 mg/L). Furthermore, <em>C. goreaui</em> cells showed a significant BP-3 uptake at the lower BP-3 concentration. BP-3 absorbing cells exhibited elevated photosynthetic efficiency, and decreased cellular carbon and nitrogen contents. Besides, the derivatives of BP-3 and aromatic amino acid metabolism highly responded to BP-3 absorption and biodegradation. Our physiological and metabolic results reveal that the symbiotic Symbiodiniaceae could resist the toxicity of a range of BP-3 through promoting cell division, photosynthesis and reprogramming amino acid metabolism. This study provides novel insights into the influences of organic UV filters to coral reef ecosystems, which urgently needs increasing attention and management.</p>
Project description:Reef-building corals live in a mutualistic relationship with photosynthetic algae (family Symbiodiniaceae) that usually provide the bulk of the energy required by the coral host. This relationship is very sensitive to temperature stress, with as little as 1°C increase above mean in sea surface temperatures (SSTs) often leading to the collapse of the association. The meta-stability of these associations has led to interest in the potential of more stress tolerant algae to supplement or substitute for the normal Symbiodiniaceae mutualists. In this respect, the apicomplexan-like microalga Chromera is of particular interest as it is considerably more temperature tolerant than are most members of the Symbiodiniaceae. Here we generated a de novo transcriptome for a Chromera strain isolated from a GBR coral (“GBR Chromera”) and compared to those of the reference strain of Chromera (“Sydney Chromera”), and to those of Symbiodiniaceae algae (Fugacium, Cladocopium and Breviolum), as well as the apicomplexan parasite, Plasmodium falciparum. By contrast with the Symbiodiniaceae, the two Chromera strains had a high level of sequence similarity evident by very low levels of divergence in orthologous genes. Although surveys of specific KEGG categories provided few general criteria by which true coral mutualists might be identified, they provide a molecular rationalization for the near ubiquitous association of Cladocopium strains with Indo-Pacific reef corals in general and with Acropora spp. in particular. In addition, HSP20 genes may underlie the higher thermal tolerance shown by Chromera compared to Symbiodiniaceae
Project description:Dinoflagellates are phytoplanktonic organisms found in both freshwater and marine habitats. They are often studied because related to harmful algal blooms responsible for impacts on ecosystem functioning, economic damages for aquaculture and fishery industries and/or deleterious impacts for human health. In addition they are also known to produce bioactive compounds, such as for the treatment of cancer or beneficial effects for the treatment of Alzheimer’s disease. The dinoflagellate Amphidinium sp. is a cosmopolitan dinoflagellate species known to produce both cytotoxic and beneficial compounds. However, several studies reported that environmental changes (e.g. nutrient starvation, UV radiation and ocean acidification) may alter this production. The aim of this study was to sequence the full transcriptome of the dinoflagellate Amphidinium carterae in both nitrogen- starved and -repleted culturing conditions (1) to evaluated its response to nitrogen starvation, (2) to look for possible polyketide synthases (PKSs), involved in the synthesis of various compounds, in this studied clone, (3) if present, to evaluate if nutrient starvation can influence PKS activity, (4) to test strain cytotoxicity on human cells and (5) to look for other possible enzymes/proteins of biotechnological interest.
Project description:af09_lignin - dml6 - Transcriptome analysis of lignin mutants and UV stress effect on secondary wall synthesis - DML6 vs S DML6+UV vs S+UV S vs S+UV DML6 vs DML6+UV Keywords: normal vs disease comparison,treated vs untreated comparison
Project description:The physiology and cellular mechanisms of the dinoflagellate symbionts of cnidarians, the Symbiodiniaceae, change as a response to symbiosis, nutrient availability, and their surrounding microhabitat, but the underlying processes are poorly understood. Here, we employed liquid chromatography–mass spectrometry-based proteomics to elucidate the changes associated with the symbiotic and nutritional states of Breviolum minutum, a native symbiont of the sea anemone Exaiptasia diaphana. Both symbiosis and nutritional state had significant impacts on the B. minutum proteome. B. minutum in hospite showed increased abundance of proteins that are involved in phosphoinositol manipulation (e.g., glycerophosphoinositol permease 1 and phosphatidylinositol phosphatase), potentially as a means of interpartner signalling to prevent host phagosomal maturation. Proteins involved in carbon concentration and fixation (e.g. carbonic anhydrase, V-type ATPase) and nitrogen assimilation (e.g. glutamine synthase) were upregulated in ex hospite B. minutum, possibly due to nitrogen limitation by host in hospite and a lack of host carbon concentration mechanisms when ex hospite, respectively. Photosystem proteins increased in abundance at high nutrient levels, as were proteins involved in antioxidant mechanisms (e.g. superoxide dismutase, glutathione s-transferase). Proteins involved in iron metabolism was also affected by nutrient state, indicating increased iron demand and uptake in low nutrient treatments. These results provide better insight on the cellular mechanisms of symbiosis and provides potential target pathways for investigating a functional cnidarian-dinoflagellate symbiosis.
Project description:Background: The molecular machinery underpinning the establishment of this relationship is not well understood. This is especially true of the symbiont side, as previous attempts to understand the interaction between coral larvae and Symbiodiniaceae have focused nearly exclusively on the host Results: The transcriptomic response of C. goreaui to the symbiotic state was complex, the most obvious feature of which was extensive and generalized downregulation of gene expression. Included in this “symbiosis-derived transcriptional repression” were a range of stress response and immune-related genes. In contrast, a range of genes implicated in metabolism were upregulated in the symbiotic state. Consistent with previous ecological studies, this transcriptomic response of C. goreaui suggests that active translocation of metabolites to the host may begin early in the colonization process, and thus that the mutualistic relationship is established at the larval stage Conclusions: This study provides novel insights into the transcriptomic remodelling that occurs in C. goreaui during transition to a symbiotic lifestyle, with important implications for understanding the establishment of symbiosis between corals and their dinoflagellate partners.
Project description:This experiment tests the effect of physiological dose of UV-B radiation on wild-type and uvr8-1 (UV Resistance Locus 8) and hy5-1 transcription factor mutants of Arabidopsis. Keywords: strain, stress response