Dataset Information

Dual-compartment shotgun proteomics unravel thermal stress responses in reef-calcifiers and their photosymbionts

ABSTRACT: The proliferation of coral reef organisms, such as the key ecological engineers and carbonate producers’ large benthic foraminifera (LBF), greatly relies on the mutual association with photosymbiotic algae. With respect to global change impacts such as ocean warming, evaluating stress and acclimatization responses is highly important, but probing proteins and partitioning host and symbionts are major obstacles for studying LBF. We therefore applied a label-free quantitative proteomics approach to LBF holobionts in order to detect changes in the relative abundances of proteins in response to different thermal-stress scenarios. Subsequent identification allowed for the partial assignment of 1,618 proteins to either foraminiferal host or endosymbiotic diatoms. While single and episodic thermal-stress events only induced minor metabolic impacts, chronic thermal stress diminished photosynthesis-related proteins among the symbionts. Stress response and proteolysis-related proteins increased in abundance, illustrating the extent of damage. In contrast to the symbionts, host homeostasis was maintained through extensive repair mechanisms and high protein turnover. Metabolic pathways were adjusted to the symbiont loss by using alternative energy resources. However, linking proteome to physiological data revealed that resource redistribution impairs growth and certainly other functions that could disturb carbonate production. We show how compartment partitioning can give insights into interactions and stress response mechanisms in photosymbiotic reef-calcifiers.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Bacillariophyta Amphistegina

SUBMITTER: Bernhard Blank-Landeshammer

LAB HEAD: Albert Sickmann

PROVIDER: PXD008015 | Pride | 2018-02-27

REPOSITORIES: Pride

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Publications

Disentangling thermal stress responses in a reef-calcifier and its photosymbionts by shotgun proteomics.

Stuhr Marleen M Blank-Landeshammer Bernhard B Reymond Claire E CE Kollipara Laxmikanth L Sickmann Albert A Kucera Michal M Westphal Hildegard H

Scientific reports 20180223 1

The proliferation of key marine ecological engineers and carbonate producers often relies on their association with photosymbiotic algae. Evaluating stress responses of these organisms is important to predict their fate under future climate projections. Physiological approaches are limited in their ability to resolve the involved molecular mechanisms and attribute stress effects to the host or symbiont, while probing and partitioning of proteins cannot be applied in organisms where the host and ...[more]

PMID: 29476118

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Project description:The association with photosymbiotic algae is crucial for the proliferation of many coral reef organisms, but increases their sensitivity to environmental changes. Large benthic foraminifera (LBF) are a diverse group of carbonate producers harboring algal photosymbionts. They act as key ecological engineers and are widely used as bioindicators. As in corals, elevated temperatures and light intensities are known to induce bleaching in LBF, but the combined effects of ocean acidification and warming remain unclear. To shed light into the adaptive physiology of LBF, we linked the assessment of the holobiont and photosymbiont physiological condition (mortality, growth, coloration, and chlorophyll a) to a bottom-up proteomics approach that allows the examination of cellular responses of host and symbionts simultaneously. In a two-months experiment, we exposed Amphistegina lobifera to the combined effects of ocean acidification (400, 1000 and 2800 ppm pCO2) and warming (28-control and 31°C). More than 1,000 proteins were identified by label-free mass spectrometry-based whole proteome analysis and assigned to the host or photosymbionts. Photopigment concentrations declined in response to elevated pCO2, visible by discoloration. These indicate the reduction of photosymbiont densities under ocean acidification, despite the fertilizing effects suggested for high inorganic carbon availability, and imply metabolic adjustments. Increases of proteolytic proteins suggest active host regulation of photosymbiont density in order to maintain homeostasis with its algal photosymbionts. Growth rates, however, were unaffected by elevated pCO2 levels at control temperatures, but high pCO2 levels (2800 ppm, pH 7.52) combined with thermal stress (31°C) impaired growth, though mortality and shell dissolution was negligible. While growth was unaffected by intermediate pCO2 levels (1000 ppm, pH 7.98) combined with ocean warming, this treatment induced the most distinct proteome responses. These include the regulation of ion transporters and host cytoplasmic proteins that likely abet calcification under ocean acidification. This study reveals a highly complex cellular response in both the host and the photosymbiont, which appears to facilitate a high resilience potential of A. lobifera to end of the century ocean conditions. Nevertheless, our results imply that when pCO2 levels rise above 1000 ppm during persistent ocean warming or extreme heating events these adaptive mechanisms become disrupted.

Project description:Southern California (USA) populations of the intertidal marine snail Chlorostoma (formerly Tegula) funebralis are generally exposed to higher air and water temperatures than northern California populations. Previous studies have shown that southern populations are more tolerant of heat stress than northern populations. To assess the potential role of gene regulation in these regional differences, we examined transcriptome responses to thermal stress in two southern and two northern populations of C. funebralis. Snails from the four populations were acclimated to a common lab environment, exposed to a heat stress representative of natural low tide conditions, and then analyzed using RNA-Seq to characterize changes in gene expression associated with stress and differences in expression across geographic regions. Changes in expression following stress were dominated by genes involved in apoptosis, the inflammatory response, response to mis and unfolded proteins, and ubiquitination of proteins. Heat shock proteins (Hsps) were up-regulated in both northern and southern populations. However, while the magnitude of the response was significantly greater in northern populations for the majority of Hsp70s, the southern populations showed a greater up-regulation for roughly half of the Hsp40s, which are co-chaperones for Hsp70s. Differential expression analysis of the control versus treatment genes in the northern and southern populations respectively revealed that 56 genes, many involved in the inflammation and immune response, responded to heat stress only in the northern populations. Moreover, several of the molecular chaperones and antioxidant genes that were not differentially expressed in the southern populations instead showed higher constitutive expression under control conditions compared to the northern populations. The expression levels of some of these constitutive genes such as superoxide dismutase were also found to positively correlate with survival following heat stress. This suggests that expression of these genes has evolved a degree of M-bM-^@M-^\frontloadingM-bM-^@M-^] that may contribute to the higher thermal tolerance of southern populations. mRNA profiles of northern and southern California heat-stressed and control C. funebralis were generated by 100bp paired end sequencing, in duplicate, using Illumina HiSeq2000.

Project description:Microarray technology provides a powerful tool for gene discovery studies, but the development of microarrays for individual species can be expensive and time-consuming. In this study, we test the suitability of a Danio rerio oligonucleotide microarray for application in a species with few genomic resources, the coral reef fish Pomacentrus moluccensis. Coral reef fishes are expected to experience rising sea surface temperatures due to climate change. How well tropical reef fish species will respond to these increased temperatures and which genes are important for resistance and adaptation to elevated temperatures is not known. Microarray technology may help identify candidate genes for thermal stress resistance in coral reef fishes. Results from a comparative genomic DNA hybridisation experiment and direct sequence comparisons indicate that for most genes there is significant sequence similarity between P. moluccensis and D. rerio, suggesting that the D. rerio array is applicable to P. moluccensis. Heterologous microarray experiments on heat-stressed P. moluccensis identified changes in transcript abundance at 120 gene loci, with many genes involved in protein processing, transcription, and cell growth. Changes in transcript abundance for a selection of candidate genes were confirmed by quantitative real-time PCR. We have demonstrated that heterologous microarrays can be successfully employed to study non-model organisms. Such a strategy thus greatly enhances the applicability of microarray technology to the field of environmental and functional genomics and will be useful for investigating the molecular basis of thermal adaptation in coral reef fishes. Keywords: stress response, comparative genomic hybridization (CGH) Common reference design [Stress response_P. moluccensis]: four individual treatment fish (heat-stressed) are contrasted in four microarray hybridisations against a pooled control consisting of four fish kept at ambient temperature. All eight fish employed in this analysis were wild-captured and are biological replicates. The experiment included dye-swap, i.e. stressed fish were labelled red in two hybridisations and green in the other two hybridisations. Common reference design [CGH_P. moluccensis and D. rerio]: four individual P. moluccensis gDNA samples are contrasted in four microarray hybridisations against a pooled gDNA sample consisting of three D. rerio. The experiment included dye-swaps.

Dataset Information

Dual-compartment shotgun proteomics unravel thermal stress responses in reef-calcifiers and their photosymbionts

Publications

Disentangling thermal stress responses in a reef-calcifier and its photosymbionts by shotgun proteomics.

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