scholarly journals Symbiodinium functional diversity and clade specificity under global change stressors

2017 ◽  
Author(s):  
S.W. Davies ◽  
J.B. Ries ◽  
A Marchetti ◽  
Rafaela Granzotti ◽  
K.D. Castillo
Keyword(s):  
Thermal Stress ◽  
Elevated Temperatures ◽  
Transcriptome Profiling ◽  
Photosynthetic Performance ◽  
Molecular Response ◽  
Functional Variation ◽  
Conserved Genes ◽  
Clade C ◽  
Highly Correlated ◽  
Photosynthetic Efficiencies

ABSTRACTCoral bleaching episodes are increasing in frequency, demanding examination of the physiological and molecular responses of corals and their Symbiodinium to climate change. Here we quantify bleaching and Symbiodinium photosynthetic performance of Siderastrea siderea from two reef zones after long-term exposure to thermal and CO2-acidification stress. Molecular response of in hospite Symbiodinium to these stressors was interrogated with RNAseq. Elevated temperatures reduced photosynthetic efficiency, which was highly correlated with bleaching status. However, photosynthetic efficiencies of forereef symbionts were more negatively affected by thermal stress than nearshore symbionts, indicating greater thermal tolerance in nearshore corals. At control temperatures, CO2-acidification had little effect on symbiont physiology, although forereef symbionts exhibited greater photosynthetic efficiencies than nearshore symbionts. Transcriptome profiling revealed that S. siderea were dominated by clade C Symbiodinium, except under thermal stress, which caused shifts to thermotolerant clade D. Comparative transcriptomics of conserved genes across symbiotic partners revealed few differentially expressed Symbiodinium genes when compared to corals. Instead of responding to stress, clade C transcriptomes varied by reef zone, with forereef Symbiodinium exhibiting enrichment of genes associated with photosynthesis. Our findings suggest that functional variation in photosynthetic architecture exists between forereef and nearshore Symbiodinium populations.

scholarly journals Warm temperatures, cool sponges: the effect of increased temperatures on the Antarctic sponge Isodictya sp.

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e8088 ◽  
Author(s):  
Marcelo González-Aravena ◽  
Nathan J. Kenny ◽  
Magdalena Osorio ◽  
Alejandro Font ◽  
Ana Riesgo ◽  
...  
Keyword(s):  
Thermal Stress ◽  
De Novo ◽  
Cold Water ◽  
Heat Exposure ◽  
Time Frame ◽  
Molecular Response ◽  
Short Term ◽  
Sres Scenarios ◽  
Ipcc Sres ◽  
The Antarctic

Although the cellular and molecular responses to exposure to relatively high temperatures (acute thermal stress or heat shock) have been studied previously, only sparse empirical evidence of how it affects cold-water species is available. As climate change becomes more pronounced in areas such as the Western Antarctic Peninsula, both long-term and occasional acute temperature rises will impact species found there, and it has become crucial to understand the capacity of these species to respond to such thermal stress. Here, we use the Antarctic sponge Isodictya sp. to investigate how sessile organisms (particularly Porifera) can adjust to acute short-term heat stress, by exposing this species to 3 and 5 °C for 4 h, corresponding to predicted temperatures under high-end 2080 IPCC-SRES scenarios. Assembling a de novo reference transcriptome (90,188 contigs, >93.7% metazoan BUSCO genes) we have begun to discern the molecular response employed by Isodictya to adjust to heat exposure. Our initial analyses suggest that TGF-β, ubiquitin and hedgehog cascades are involved, alongside other genes. However, the degree and type of response changed little from 3 to 5 °C in the time frame examined, suggesting that even moderate rises in temperature could cause stress at the limits of this organism’s capacity. Given the importance of sponges to Antarctic ecosystems, our findings are vital for discerning the consequences of short-term increases in Antarctic ocean temperature on these and other species.

scholarly journals Transcriptome Profiling of Shewanella oneidensis Gene Expression following Exposure to Acidic and Alkaline pH

2006 ◽  
Vol 188 (4) ◽  
pp. 1633-1642 ◽  
Author(s):  
Adam B. Leaphart ◽  
Dorothea K. Thompson ◽  
Katherine Huang ◽  
Eric Alm ◽  
Xiu-Feng Wan ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acid ◽  
Cell Envelope ◽  
Sulfur Metabolism ◽  
Shewanella Oneidensis ◽  
Acid Stress ◽  
Transcriptome Profiling ◽  
Molecular Response ◽  
Alkaline Ph ◽  
Expression Of Genes

ABSTRACT The molecular response of Shewanella oneidensis MR-1 to variations in extracellular pH was investigated based on genomewide gene expression profiling. Microarray analysis revealed that cells elicited both general and specific transcriptome responses when challenged with environmental acid (pH 4) or base (pH 10) conditions over a 60-min period. Global responses included the differential expression of genes functionally linked to amino acid metabolism, transcriptional regulation and signal transduction, transport, cell membrane structure, and oxidative stress protection. Response to acid stress included the elevated expression of genes encoding glycogen biosynthetic enzymes, phosphate transporters, and the RNA polymerase sigma-38 factor (rpoS), whereas the molecular response to alkaline pH was characterized by upregulation of nhaA and nhaR, which are predicted to encode an Na+/H+ antiporter and transcriptional activator, respectively, as well as sulfate transport and sulfur metabolism genes. Collectively, these results suggest that S. oneidensis modulates multiple transporters, cell envelope components, and pathways of amino acid consumption and central intermediary metabolism as part of its transcriptome response to changing external pH conditions.

173 HINDERING OF CLEAVAGE TIMING IN BOVINE PARTHENOTES DURING THE HOT SEASON

2007 ◽  
Vol 19 (1) ◽  
pp. 203 ◽  
Author(s):  
A. Aroyo ◽  
S. Yavin ◽  
Z. Roth ◽  
A. Arav
Keyword(s):  
Thermal Stress ◽  
Embryonic Development ◽  
Elevated Temperatures ◽  
Time Lapse ◽  
Cold Season ◽  
Seasonal Effects ◽  
Cell Stage ◽  
Developmental Potential ◽  
Hot Season

Heat stress is a major contributing factor to low fertility among dairy cattle, as reflected by the dramatic reduction in conception rate during the hot months. The effects of thermal stress on oocyte competence and embryonic development have been well documented. However, timing of embryonic cleavage, which may be considered a parameter for the identification of good-quality embryos, and its association with elevated temperatures have not been studied. Two experiments were performed to examine and characterize seasonal effects (i.e. thermal stress) on cleavage timing of bovine parthenogenetic embryos. Oocytes were aspirated from ovaries collected at the local abattoir in 2 seasons: cold (Dec–Apr) and hot (May–Nov). Matured oocytes were chemically activated (ionomycin followed by 6-DMAP) and cultured in vitro; cleavage timing to the 2- and 4-cell stages was observed and documented. The one-way ANOVA procedure was used for statistical analysis. In the first experiment (n = 5416 oocytes), cleavage was documented at specific time points during development post-activation. The peak in embryonic development to the 2-cell stage was earlier (22 to 27 vs. 27 to 40 h after activation) and the cleavage rate higher (39 vs. 21%; P < 0.0001) during the cold season relative to the hot season, respectively. Similarly, the peak in 4-cell-stage development was also observed earlier (46–52 vs. 52–70 h after activation) and corresponded with a higher proportion of developing embryos (33 vs. 21%; P < 0.0001) during the cold season as compared to the hot season, respectively. These results indicate that embryonic development is delayed and a lower proportion of embryos cleaved during the hot season. To better understand the delay in cleavage timing, a second experiment (n = 308 oocytes) was performed through two consecutive hot seasons. A time-lapse system (EmbryoGuard; IMT, Ltd., Ness-Ziona, Israel) was employed to collect accurate data on the first cleavage division, known to be indicative of embryo quality. The time-lapse system was pre-programmed to take photos at 1-h intervals such that culture dishes did not need to be removed from the incubator. Similar to the pattern noted for the hot season in the first experiment, a wide distribution of cleavage timing (18-40 h after activation) was observed. Further analysis revealed that embryos cleaved in 2 distinct waves: cleavage timing of the first wave (18 to 25 h after activation) was characterized by a time frame similar to that in the cold season, suggesting good-quality embryos; however, the second wave, from 27 to 40 h after activation, presented a delay in cleavage timing, suggesting that these late-cleaving embryos are of inferior quality. Taken together, the results of the 2 experiments lead to the assumption that oocytes harvested from lactating cows during the hot season are of reduced developmental potential, which may be explained, in part, by the pattern of 2 cleavage waves. Furthermore, cleavage timing appears to be a good indicator of embryo potential and may increase the chances of selecting better in vitro-derived embryos during the hot season for embryo transfer.

scholarly journals Global Molecular and Morphological Effects of 24-Hour Chromium(VI) Exposure on Shewanella oneidensis MR-1

2006 ◽  
Vol 72 (9) ◽  
pp. 6331-6344 ◽  
Author(s):  
Karuna Chourey ◽  
Melissa R. Thompson ◽  
Jennifer Morrell-Falvey ◽  
Nathan C. VerBerkmoes ◽  
Steven D. Brown ◽  
...  
Keyword(s):  
Untreated Control ◽  
Expression Profiles ◽  
Shewanella Oneidensis ◽  
Transcriptome Profiling ◽  
Molecular Response ◽  
Chromium Vi ◽  
Stress Protection ◽  
Gene And Protein Expression ◽  
Genes Encoding ◽  
Protein Expression Profiles

ABSTRACT The biological impact of 24-h (“chronic”) chromium(VI) [Cr(VI) or chromate] exposure on Shewanella oneidensis MR-1 was assessed by analyzing cellular morphology as well as genome-wide differential gene and protein expression profiles. Cells challenged aerobically with an initial chromate concentration of 0.3 mM in complex growth medium were compared to untreated control cells grown in the absence of chromate. At the 24-h time point at which cells were harvested for transcriptome and proteome analyses, no residual Cr(VI) was detected in the culture supernatant, thus suggesting the complete uptake and/or reduction of this metal by cells. In contrast to the untreated control cells, Cr(VI)-exposed cells formed apparently aseptate, nonmotile filaments that tended to aggregate. Transcriptome profiling and mass spectrometry-based proteomic characterization revealed that the principal molecular response to 24-h Cr(VI) exposure was the induction of prophage-related genes and their encoded products as well as a number of functionally undefined hypothetical genes that were located within the integrated phage regions of the MR-1 genome. In addition, genes with annotated functions in DNA metabolism, cell division, biosynthesis and degradation of the murein (peptidoglycan) sacculus, membrane response, and general environmental stress protection were upregulated, while genes encoding chemotaxis, motility, and transport/binding proteins were largely repressed under conditions of 24-h chromate treatment.

scholarly journals Coral Bleaching Resistance vs Susceptibility: The Role of Antioxidant Activity in Symbiotic Dinoflagellates

2021 ◽  
Author(s):  
◽  
Anne Wietheger
Keyword(s):  
Oxidative Stress ◽  
Antioxidant Activity ◽  
Thermal Stress ◽  
Coral Bleaching ◽  
Stress Responses ◽  
Antioxidant Activities ◽  
Photosynthetic Performance ◽  
Gulf Of Aqaba ◽  
Different Types ◽  
And Oxidative Stress

<p>Coral bleaching, the loss of symbiotic dinoflagellate algae (genus Symbiodinium) and/or photosynthetic algal pigments from their coral host has become a regular occurrence in the last few decades due to increasing seawater temperatures. A key consideration in bleaching susceptibility is the symbiotic alga‘s physiology and its capacity to deal with abiotic stress; oxidative stress is of particular interest given that this can arise from thermally induced photosynthetic dysfunction. The aim of this study was to compare the effects of thermal and oxidative stress on the photosynthetic performance of a range of Symbiodinium clades and types (i.e. sub-clades) in different states of symbiosis (in hospite, freshly isolated and in culture). Whether the responses to these two stressors are related was investigated; in particular, it was hypothesised that more thermally sensitive types would be more sensitive to oxidative stress. Furthermore, the study aimed to elucidate the role of antioxidants in the observed stress responses. The specific objectives were 1) to establish whether different types of cultured Symbiodinium have dissimilar sensitivities to oxidative stress, induced by hydrogen peroxide (H₂O₂), and whether these are related to their thermal sensitivities; 2) measure the activity and relative amounts of specific reactive oxygen species (ROS) in different types of cultured Symbiodinium in response to thermal and oxidative stress induced by H₂O₂; 3) measure total antioxidant activity in different cultured Symbiodinium types when under oxidative stress; and 4) compare and contrast the responses of different Symbiodinium types to thermal and oxidative stress when in hospite (i.e. in corals) and freshly isolated. In this study, I showed that different Symbiodinium clades and types can differ widely in their responses to both thermal and oxidative stress. This was indicated by photosynthetic performance measured by chlorophyll fluorescence, and differences in the quantity of specific ROS measured via fluorescent probes and flow cytometry. For instance, when adding H₂O₂ to Symbiodinium F1, originally from Hawaii, a decrease of > 99% in maximum quantum yield (Fv/Fm) was displayed, while there was no change in Fv/Fm in the temperate Symbiodinium A1, freshly isolated from the anemone Anthopleura aureoradiata from New Zealand. When comparing the difference in ROS production between the control (26 °C) and a thermal stress treatment (35 °C), type E1 from Okinawa showed no difference in any of the measured ROS. In contrast, a different A1 type from the Gulf of Aqaba displayed an increase in the overall production of ROS, and more specifically in the production of superoxide. Symbiodinium types also displayed differential oxidative stress resistance, which was apparent from their antioxidant activities; in particular, total antioxidant capacity was measured by the ferric reducing antioxidant potential (FRAP) and cellular antioxidant activity (CAA) assays. For example, the aforementioned Symbiodinium types, A1 from the Gulf of Aqaba and F1, increased their antioxidant activities with increasing H₂O₂ concentrations. Meanwhile, type E1 displayed higher baseline levels of antioxidants in comparison to the other two types (A1, F1), which then decreased with increasing H₂O₂. Specific activities of superoxide dismutase and ascorbate peroxidase were also measured. Stress susceptibility appears to be related both to Symbiodinium type and geographic origin, but greater sensitivity to thermal stress did not necessarily correlate with greater susceptibility to oxidative stress. The exact relationship between thermal and oxidative sensitivities in Symbiodinium spp. remains elusive, but it is suggested that different types might follow different strategies for dealing with stress. I propose that some Symbiodinium types rely more on photo-protection when exposed to thermal stress (and hence cope less with oxidative stress), while other types depend more on antioxidants and oxidative stress resistance. The latter might be the better strategy for types from more variable environments, such as higher latitude reefs or intertidal regions, where potentially stressful conditions may be encountered more frequently. This study gives new insights into the variability of stress responses in the genus Symbiodinium, and the complex relationship between thermal and oxidative stress. The implications of these findings for coral bleaching susceptibility and the biogeographic distribution of different Symbiodinium types are discussed.</p>

scholarly journals Transcriptome Profiling Revealed Candidate Genes, Pathways and Transcription Factors Related to Nitrogen Utilization and Excessive Nitrogen Stress in Perennial Ryegrass

2021 ◽  
Author(s):  
Yinruizhi Li ◽  
Mengdi Wang ◽  
Ke Teng ◽  
Di Dong ◽  
Zhuocheng Liu ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Perennial Ryegrass ◽  
Expression Patterns ◽  
Enrichment Analysis ◽  
Transcriptome Profiling ◽  
Nitrogen Utilization ◽  
Utilization Efficiency ◽  
Nitrogen Stress ◽  
Molecular Response ◽  
Stress Effect

Abstract Ryegrass (Lolium perenne L.) is a type of the high quality forage grasses, which can be a good nutritional source for herbivorous livestock. However, improving the nitrogen utilization efficiency and avoiding the nitrate toxicity caused by excessive nitrogen have long been the challenging tasks in ryegrass. The molecular response mechanism of ryegrass to nitrogen, especially under the condition of excessive nitrogen, remains unclear. In this study, the transcription of perennial ryegrass at different nitrogen levels was identified by high-throughput next-generation RNA sequencing. Phenotypic characterizations showed that ryegrass in treatment N0.5 had a better growth state than the other three groups. Treatments N1 and N10 contained excessive nitrogen, which had a stress effect on plant growth. Analysis of differentially expressed genes indicated that 345 and 104 genes are involved in the regulation of nitrogen utilization and excessive nitrogen stress, respectively. GO enrichment analysis revealed that the plant response to nitrogen was mainly enriched in two categories, including “biological process” and “molecular function”. KEGG enrichment analysis suggested that “Photosynthesis-antenna proteins” may respond positively to nitrogen under appropriate nitrogen conditions, whereas “steroid biosynthesis”, “carotenoid biosynthesis” and “C5-branched dibasic acid metabolism” were identified as the top significantly enriched pathways in response to excessive nitrogen. Transcription factor analysis showed that 21 TFs related to nitrogen utilization were classified into 10 transcription factor families, especially the AP2-EREBP and MYB TF families. Four TFs related to excessive nitrogen stress were identified, including LOB, NAC, AP2-EREBP and HB. The expression patterns of these selected genes were also analyzed.

scholarly journals Thermal Stress and Bleaching in the Cnidarian-Dinoflagellate Symbiosis: The Application of Metabolomics

2021 ◽  
Author(s):  
◽  
Katie E. Hillyer
Keyword(s):  
Thermal Stress ◽  
Coral Reefs ◽  
Metabolite Profiling ◽  
Alternative Energy ◽  
Metabolic Networks ◽  
Elevated Temperatures ◽  
Central Metabolism ◽  
Diverse Range ◽  
Thermally Induced ◽  
Profiling Techniques

<p>Reef-building corals form critical ecosystems, which provide a diverse range of goods and services. Their success is based on a complex symbiosis between cnidarian host, dinoflagellate algae (genus Symbiodinium) and associated microorganisms (together termed the holobiont). Under functional conditions nutrients are efficiently recycled within the holobiont; however, under conditions of thermal stress, this dynamic relationship can dysfunction, resulting in the loss of symbionts (bleaching). Mass coral bleaching associated with elevated temperatures is a major threat to the long-term persistence of coral reefs. Further study is therefore necessary in order to elucidate the cellular and metabolic networks associated with function in the symbiosis and to determine change elicited by exposure to thermal stress. Metabolomics is the study of small compounds (metabolites) in a cell, tissue or whole organism. The metabolome comprises thousands of components, which will respond rapidly to change, reflecting a combination of genotype, phenotype and the environment. As a result, the study of these metabolic networks serves as a sensitive tool for the detection and elucidation of cellular responses to abiotic stress in complex systems.  This thesis presents outputs of gas chromatography-mass spectrometry-based metabolite profiling techniques, which have been applied to the study of thermal stress and bleaching in the cnidarian-dinoflagellate symbiosis. In Chapter 2 these techniques were developed and applied to the model symbiotic cnidarian Aiptasia sp., and its homologous symbiont (Symbiodinium ITS 2 type B1), to characterise both ambient and thermally-induced metabolite profiles (amino and non-amino organic acids) in both partners. Thermal stress, symbiont photodamage and associated bleaching, resulted in characteristic modifications to the free metabolite pools of both partners. These changes differed between partners and were associated with modifications to central metabolism, biosynthesis, catabolism of stores and homeostatic responses to thermal and oxidative stress.  In Chapter 3 metabolite profiling techniques (focussing this time on carbohydrate pools) were once again applied to the study of thermally-induced changes to the free pools of the coral Acropora aspera and its symbionts (dominant Symbiodinium ITS 2 type C3) at differing stages of symbiont photodamage and thermal stress. Additionally, targeted analysis was employed to quantify these changes in terms of absolute amounts. Once again exposure to elevated temperatures resulted in symbiont photodamage, bleaching and characteristic modifications to the free metabolite pools of symbiont and host, which differed between partners and with the duration of thermal stress. These changes were associated with increased turnover of a number of networks including: energy-generating pathways, antioxidant networks, ROS-associated damage and damage signalling, and were also indicative of potential alterations to the composition of the associated microbial holobiont.  Finally in Chapter 4, metabolite profiling techniques optimized in Chapter 2 and 3 were coupled to 13C labelling in both Aiptasia sp. and A. aspera, in order to further investigate the questions raised in these preceding studies. Once again changes were observed to central metabolism, biosynthesis and alternative energy-generation modes in symbiont and host, in both symbioses. Interestingly however, in all cases there was continued fixation of carbon, production- and translocation of mobile products by the remaining symbionts in hospite. This suggests that even during the later stages of bleaching, symbionts are, at least in part, metabolically functional in terms of photosynthate provision.  This study therefore serves as an important first step in developing the application of metabolomics-based techniques to the study of thermal stress in the cnidarian-dinoflagellate symbiosis. The power of these techniques lies in the capacity to simultaneously assess rapid and often post-translational change in a highly repeatable and quantitative manner. With the use of these methods, this study has shown how metabolic, homeostatic and acclimatory networks interact to elicit change in each partner of the symbiosis during thermal stress and how these responses vary between symbiotic partners. Further understanding of these networks, individual sensitivities- and enhanced resistance to thermal stress are essential if we are to better understand the capacity of coral reefs to acclimate and persist in the face of climate change.</p>

Thermal Stress Effects of Thin Superconducting Films

1968 ◽  
Vol 26 ◽  
pp. 386-387
Author(s):  
M. Connella ◽  
R. J. Deck ◽  
R. H. Morriss
Keyword(s):  
Thermal Stress ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
Superconducting Films ◽  
Temperature Cycle ◽  
Superconducting Properties ◽  
Replication Method ◽  
Thermal Expansion Coefficients ◽  
Before And After ◽  
The Difference

In order to completely understand the role of microstructural defects in superconductivity, it is very desirable to have quantitative correlations between superconducting properties and structural properties. This research is part of a study to correlate grain-sizes with “flux creep phenomena” which occur in the mixed state of Type II superconducting films. Since the superconducting properties in our study must be observed at liquid helium temperatures, whereas the films are evaporated at elevated temperatures, the structural changes produced in some films by cycling to 4.2°K have been investigated.As the temperature of a film is lowered, the difference in thermal expansion coefficients of a film and its substrate results in thermal stress. This stress can produce structural changes. Films have been examined by electron microscopy techniques before and after a temperature cycle down to 4.2°K and back to room temperature. All temperature cycles were carried out in approximately 20 minutes. Both transmission and replication techniques have been employed. The direct replication method was employed using carbon. The carbon replica was separated from the film and post-shadowed with Pt-C.

Sign in / Sign up

Export Citation Format

Share Document