scholarly journals Thermally tolerant symbionts may explain Caribbean octocoral resilience to heat stress

2020 ◽  
Author(s):  
Jessie Pelosi ◽  
Katherine M. Eaton ◽  
Samantha Mychajliw ◽  
Casey P. terHorst ◽  
Mary Alice Coffroth
Keyword(s):  
Heat Stress ◽  
Thermal Tolerance ◽  
Elevated Temperatures ◽  
Model System ◽  
Sea Surface ◽  
Coral Reef Ecosystems ◽  
Historical Temperature ◽  
Broad Scale

AbstractCoral reef ecosystems are under threat from the frequent and severe impacts of anthropogenic climate change, particularly rising sea surface temperatures. The effects of thermal stress may be ameliorated by adaptation and/or acclimation of the host, symbiont, or holobiont (host + symbiont) to increased temperatures. We examined the role of the symbiont in promoting thermal tolerance of the holobiont, using Antillogorgia bipinnata (octocoral host) and Breviolum antillogorgium (symbiont) as a model system. We identified five distinct genotypes of B. antillogorgium from symbiont populations isolated from A. bipinnata colonies. Three symbiont genotypes were maintained at 26°C (ambient historical temperature) and two were maintained at 30°C (elevated historical temperature) for two years. We analyzed the in vitro growth rate and carrying capacity of each genotype at both ambient and elevated temperatures. All genotypes grew well at both temperature treatments, indicating thermal tolerance among these B. antillogorgium genotypes. We also inoculated juvenile A. bipinnata polyps with each of the five symbiont genotypes, and reared these polyps at both ambient and elevated temperatures. All genotypes were able to infect polyps at both temperature treatments. Survivorship of polyps at 30°C was significantly lower than survivorship at 26°C, but all treatments had surviving polyps at 56 days post-infection, suggestive of broad-scale thermal tolerance in this system. The widespread thermal tolerance observed in B. antillogorgium may play a part in the increased resilience of Caribbean octocorals during heat stress events.

scholarly journals Thermally tolerant symbionts may explain Caribbean octocoral resilience to heat stress

Coral Reefs ◽  
2021 ◽  
Author(s):  
Jessie Pelosi ◽  
Katherine M. Eaton ◽  
Samantha Mychajliw ◽  
Casey P. terHorst ◽  
Mary Alice Coffroth
Keyword(s):  
Heat Stress ◽  
Thermal Tolerance ◽  
Elevated Temperatures ◽  
Florida Keys ◽  
Coral Reef Ecosystems ◽  
History Of ◽  
Historical Temperature

AbstractCoral reef ecosystems are under threat from the frequent and severe impacts of anthropogenic climate change, particularly rising sea surface temperatures. The effects of thermal stress may be ameliorated by adaptation and/or acclimation of the host, symbiont, or holobiont (host + symbiont) to increased temperatures. We examined the role of the symbiont in promoting thermal tolerance of the holobiont, using Antillogorgia bipinnata (octocoral host) and Breviolum antillogorgium (symbiont) as a model system. We identified five distinct genotypes of B. antillogorgium from symbiont populations isolated from Antillogorgia colonies in the Florida Keys. Three symbiont genotypes were cultured and maintained at 26 °C (ambient historical temperature), and two were cultured and maintained at 30 °C (elevated historical temperature) for 2 yrs. We analyzed the growth rate and carrying capacity of each symbiont genotype at both ambient and elevated temperatures in culture (in vitro). All genotypes grew well at both temperatures, indicating that thermal tolerance exists among these B. antillogorgium cultures. However, a history of long-term growth at 30 °C did not yield better performance for B. antillogorgium at 30 °C (as compared to 26 °C), suggesting that prior culturing at the elevated temperature did not result in increased thermal tolerance. We then inoculated juvenile A. bipinnata polyps with each of the five symbiont genotypes and reared these polyps at both ambient and elevated temperatures (in hospite experiment). All genotypes established symbioses with polyps in both temperature treatments. Survivorship of polyps at 30 °C was significantly lower than survivorship at 26 °C, but all treatments had surviving polyps at 56 d post-infection. Our results suggest broad thermal tolerance in B. antillogorgium, which may play a part in the increased resilience of Caribbean octocorals during heat stress events.

scholarly journals Porphyromonas gingivalis lipopolysaccharide stimulation in human periodontal ligament stem cells: role of epigenetic modifications to the inflammation

2017 ◽  
Vol 61 (3) ◽  
Author(s):  
Francesca Diomede ◽  
Soundara Rajan Thangavelu ◽  
Ilaria Merciaro ◽  
Monica D'Orazio ◽  
Placido Bramanti ◽  
...  
Keyword(s):  
Stem Cells ◽  
Porphyromonas Gingivalis ◽  
Inflammatory Disease ◽  
Periodontal Ligament ◽  
Model System ◽  
Epigenetic Mechanism ◽  
Periodontal Ligament Stem Cells ◽  
Porphyromonas Gingivalis Lipopolysaccharide

<p>Periodontitis is a chronic oral inflammatory disease produced by bacteria. Gingival retraction and bone and connective tissues resorption are the hallmarks of this disease. Chronic periodontitis may contribute to the risk of onset or progression of neuroinflammatory pathological conditions, such as Alzheimer’s disease. The main goal of the present study was to investigate if the role of epigenetic modulations is involved in periodontitis using human periodontal ligament stem cells (hPDLSCs) as an <em>in vitro</em> model system. hPDLSCs were treated with lipopolysaccharide of <em>Porphyromonas gingivalis</em> and the expression of proteins associated with DNA methylation and histone acetylation, such as DNMT1 and p300, respectively, and inflammatory transcription factor NF-kB, were examined. Immunofluorescence, Western blot and next generation sequencing results demonstrated that <em>P. gingivalis </em>lipopolysaccharide significantly reduced DNA methylase DNMT1, while it markedly upregulated the level of histone acetyltransferase p300 and NF-kB in hPDLSCs. Our results showed that <em>P. gingivalis </em>lipopolysaccharide markedly regulate the genes involved in epigenetic mechanism, which may result in inflammation induction. We propose that <em>P. gingivalis </em>lipopolysaccharide-treated hPDLSCs could be a potential in vitro model system to study epigenetics modulations associated with periodontitis, which might be helpful to identify novel biomarkers linked to this oral inflammatory disease.</p>

scholarly journals DNA methylation regulates transcriptional homeostasis of algal endosymbiosis in the coral modelAiptasia

2017 ◽  
Author(s):  
Yong Li ◽  
Yi Jin Liew ◽  
Guoxin Cui ◽  
Maha J Cziesielski ◽  
Noura Zahran ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Molecular Mechanisms ◽  
Model System ◽  
Epigenetic Mechanism ◽  
Symbiotic Relationship ◽  
Epigenetic Mechanisms ◽  
Genome Wide ◽  
Spurious Transcription ◽  
Coral Reef Ecosystems

The symbiotic relationship between cnidarians and dinoflagellates is the cornerstone of coral reef ecosystems. Although research is focusing on the molecular mechanisms underlying this symbiosis, the role of epigenetic mechanisms, which have been implicated in transcriptional regulation and acclimation to environmental change, is unknown. To assess the role of DNA methylation in the cnidarian-dinoflagellate symbiosis, we analyzed genome-wide CpG methylation, histone associations, and transcriptomic states of symbiotic and aposymbiotic anemones in the model systemAiptasia. We find methylated genes are marked by histone H3K36me3 and show significant reduction of spurious transcription and transcriptional noise, revealing a role of DNA methylation in the maintenance of transcriptional homeostasis. Changes in DNA methylation and expression show enrichment for symbiosis-related processes such as immunity, apoptosis, phagocytosis recognition and phagosome formation, and unveil intricate interactions between the underlying pathways. Our results demonstrate that DNA methylation provides an epigenetic mechanism of transcriptional homeostasis during symbiosis.

The Role of CXCR4 Inhibitors as Novel Antiangiogenesis Agents in Cancer Therapy.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1296-1296
Author(s):  
Irene M. Ghobrial ◽  
Michael M. Timm ◽  
Karen E. Hedin ◽  
Thomas E. Witzig
Keyword(s):  
Endothelial Cells ◽  
Map Kinase ◽  
Kinase Inhibitor ◽  
Negative Control ◽  
Model System ◽  
Significant Inhibition ◽  
Inhibitory Antibody ◽  
Inhibition Of Angiogenesis

Abstract Angiogenesis plays an important role in tumor growth. Endothelial cells express the chemokine receptor CXCR4, and interact with its ligand SDF-1/CXCL12. Previous studies have demonstrated that the ERK MAP kinase and the PI3Kinase pathways are activated in response to SDF-1 stimulation. In this study, we investigate the effect of the role of inhibitors of CXCR4, ERK MAP kinase and PI3Kinase on angiogenesis. The AngioKit (TCS Cellworks, U.K) is a 24 well plate in which human endothelial cells are co-cultured with other human myoblasts and fibroblasts in a specially designed medium. Control wells in the kit include media alone, VEGF (+control) and suramin (-control). Test samples were added on the day the kits arrive, then changed on days 4, 7, and 9, and stained on day 11 with CD31 (PECAM). The wells are then photographed and subjected to image analysis. The software measures angiogenesis as total tubule length per well in microns. Test samples can then be compared to the control wells to determine the drugs affect on angiogenesis in vitro. The following drugs were tested in this angiogenesis model system, a human CXCR4 neutralizing antibody (MAB 171, R&D systems, MN), SDF-1, the MAP kinase inhibitor PD098059, and the PI3Kinase inhibitor LY294002. Treatment with the CXCR4 inhibitory antibody, PD098059, and LY294002 caused marked decrease in angiogenesis (below the level of the negative control suramin). Inhibition of angiogenesis below the level of suramin was first detected at 1mg/ml CXCR4 antibody, and10mg/ml CXCR4 antibody resulted in complete inhibition of angiogenesis. The effect of PD098059 on angiogenesis was dependent on its concentration; 20mM PD098059 inhibited angiogenesis while lower concentrations did not. These results are consistent with the drug’s known concentration-dependent inhibition of MEK-1 and indicate that the MEK-1 inhibitor leads to angiostasis secondary to its specific inhibitory effect on MEK-1. The lowest level tested of 1μM LY294002 led to inhibition of angiogenesis, and 50μM of LY294002 led to complete abrogation of angiogenesis. SDF-1 has been reported to be angiogenic. In this model system, the effect of SDF-1 alone on angiogenesis was subtle. However, the endothelial cells used in this model system may be secreting endogenous SDF-1 leading to the saturation of the CXCR4 receptor and minimal effects of exogenous SDF-1 stimulation. This was demonstrated by the significant effect of the CXCR4 inhibitor on angiogenesis without the addition of exogenous SDF-1. These results indicate that CXCR4 inhibition and its downstream pathways PI3K and ERK MAP kinase lead to significant inhibition of angiogenesis, and suggest that selective inhibitors of CXCR4 may be useful agents to inhibit angiogenesis.

scholarly journals Heat-evolved microalgal symbionts increase coral bleaching tolerance

2020 ◽  
Vol 6 (20) ◽  
pp. eaba2498 ◽  
Author(s):  
P. Buerger ◽  
C. Alvarez-Roa ◽  
C. W. Coppin ◽  
S. L. Pearce ◽  
L. J. Chakravarti ◽  
...  
Keyword(s):  
Coral Bleaching ◽  
Thermal Tolerance ◽  
Carbon Fixation ◽  
Elevated Temperatures ◽  
Heat Waves ◽  
Constitutive Expression ◽  
Coral Host ◽  
Laboratory Evolution ◽  
Climate Resilience

Coral reefs worldwide are suffering mass mortalities from marine heat waves. With the aim of enhancing coral bleaching tolerance, we evolved 10 clonal strains of a common coral microalgal endosymbiont at elevated temperatures (31°C) for 4 years in the laboratory. All 10 heat-evolved strains had expanded their thermal tolerance in vitro following laboratory evolution. After reintroduction into coral host larvae, 3 of the 10 heat-evolved endosymbionts also increased the holobionts’ bleaching tolerance. Although lower levels of secreted reactive oxygen species (ROS) accompanied thermal tolerance of the heat-evolved algae, reduced ROS secretion alone did not predict thermal tolerance in symbiosis. The more tolerant symbiosis exhibited additional higher constitutive expression of algal carbon fixation genes and coral heat tolerance genes. These findings demonstrate that coral stock with enhanced climate resilience can be developed through ex hospite laboratory evolution of their microalgal endosymbionts.

257 DEVELOPMENT OF HEAT-STRESSED OVA MATURED IN THE PRESENCE OF A PROSTAGLANDIN F2ALPHA RECEPTOR ANTAGONIST

2009 ◽  
Vol 21 (1) ◽  
pp. 226
Author(s):  
A. M. Ward ◽  
F. N. Schrick ◽  
R. R. Payton ◽  
E. Peixoto ◽  
J. L. Edwards
Keyword(s):  
Heat Stress ◽  
Receptor Antagonist ◽  
Fixed Effects ◽  
In Vitro Maturation ◽  
Elevated Temperatures ◽  
Block Design ◽  
Developmental Competence ◽  
In Vitro Production ◽  
Blastocyst Development

Studies in the literature have shown that cumulus–oocyte complexes produce PGF2α, that ova and cumulus cells have PGF2α receptors, and that PGF2α addition to maturing ova, above what would normally be produced, decreases blastocyst development. Because previous studies have shown elevated systemic and tissue levels of PGF2α as a consequence of heat stress, it was hypothesized that detrimental effects of exposing maturing ova to elevated temperatures may be mediated in part through heat-induced increases in PGF2α. To test this hypothesis, cumulus–oocyte complexes were matured at 38.5 or 41.0°C in the presence of a PGF2α receptor antagonist (AL-8810). Preattachment embryo development of AL-8810-treated ova was compared with development of ova matured in media with or without diluent (DMSO added at the same concentration as AL-8810; diluent and developmental controls, respectively), resulting in 6 total treatment combinations. Data were analyzed as a randomized block design (blocking on oocyte collection date) with fixed effects of maturation temperature, AL-8810, and the respective interaction included in the statistical model. In experimental replicates in which the effects of heat stress decreased blastocyst development greater than 10% (n = 14), a significant maturation temperature × AL-8810 interaction was noted when evaluating blastocyst development (P = 0.05). Specifically, when ova were heat stressed during the first 12 h of in vitro maturation, blastocyst development was reduced in developmental and diluent controls (26.2 v. 18.8 and 24.4 v. 19.9, respectively; SEM = 1.6). In contrast, when ova were matured under the same conditions but in the presence of a PGF2α receptor antagonist, the effects of heat stress to reduce blastocyst development after in vitro fertilization were no longer observed (22.5 v. 22.5; SEM = 1.6). When using abattoir-derived ovaries, it is not uncommon to collect, on occasion, ova that are developmentally challenged (i.e. blastocyst development is less than the 20 to 50% expected). In this experiment, this occurred on 5 occasions. Data from these experimental replicates were analyzed and reported separately because previous efforts had shown that the responsiveness of ova to changes in culture environment differs depending on the level of developmental competence. Relevant to this study, addition of AL-8810 to developmentally challenged ova matured under thermoneutral conditions increased cleavage (60.4 v. 55.4%, respectively; P = 0.06) and blastocyst development (17.7 v. 13.7%, respectively; P = 0.07). In summary, data illustrate that developmentally challenged ova, heat-stressed or otherwise, are susceptible to detrimental effects of PGF2α. The ability to increase blastocyst development approaching or exceeding the values expected for competent ova suggests the usefulness of a PGF2α receptor antagonist during in vitro maturation to improve the efficiency of in vitro production procedures.

The Role of DNA Polymerase in the Production of UV-Induced Mutations in an in Vitro Model System

1994 ◽  
Vol 726 (1 DNA Damage) ◽  
pp. 364-366
Author(s):  
DAPHNA SAGHER ◽  
EDITH TURKINGTON ◽  
SONIA ACHARYA ◽  
BERNARD STRAUSS
Keyword(s):  
Dna Polymerase ◽  
In Vitro Model ◽  
Model System ◽  
Induced Mutations ◽  
In Vitro Model System ◽  
Vitro Model

scholarly journals A stutter in the coiled coil domain of E.coli co-chaperone GrpE connects structure with function

2020 ◽  
Author(s):  
Tulsi Upadhyay ◽  
Vaibhav V Karekar ◽  
Ishu Saraogi
Keyword(s):  
Heat Stress ◽  
Coiled Coil ◽  
Bacterial Survival ◽  
Nucleotide Exchange ◽  
E Coli ◽  
Coiled Coil Domain ◽  
Nucleotide Exchange Factor ◽  
First Time

AbstractIn bacteria, the co-chaperone GrpE acts as a nucleotide exchange factor and plays an important role in controlling the chaperone cycle of DnaK. The functional form of GrpE is an asymmetric dimer, consisting of a long non-ideal coiled-coil. During heat stress, this region partially unfolds and prevents DnaK nucleotide exchange, ultimately ceasing the chaperone cycle. In this study, we elucidate the role of thermal unfolding of the coiled-coil domain of E. coli GrpE in regulating its co-chaperonic activity. The presence of a stutter disrupts the regular heptad arrangement typically found in an ideal coiled coil resulting in structural distortion. Introduction of hydrophobic residues at the stutter altered the structural stability of the coiled-coil. Using an in vitro FRET assay, we show for the first time that the enhanced stability of GrpE resulted in an increased affinity for DnaK. However, the mutants were defective in in vitro functional assays, and were unable to support bacterial growth at heat shock temperature in a grpE-deleted E. coli strain. This work provides valuable insights into the functional role of a stutter in the GrpE coiled-coil, and its role in regulating the DnaK-chaperone cycle for bacterial survival during heat stress. More generally, our findings illustrate how a sequence specific stutter in a coiled-coil domain regulates the structure function trade-off in proteins.

scholarly journals Gut Microbiota of Drosophila subobscura Contributes to Its Heat Tolerance and Is Sensitive to Transient Thermal Stress

2021 ◽  
Vol 12 ◽  
Author(s):  
Angélica Jaramillo ◽  
Luis E. Castañeda
Keyword(s):  
Heat Stress ◽  
Community Structure ◽  
Thermal Stress ◽  
Gut Microbiota ◽  
Heat Tolerance ◽  
Thermal Tolerance ◽  
Drosophila Subobscura ◽  
Transient Thermal ◽  
The Impact

The gut microbiota can contribute to host physiology leading to an increase of resistance to abiotic stress conditions. For instance, temperature has profound effects on ectotherms, and the role of the gut microbiota on the thermal tolerance of ectotherms is a matter of recent research. However, most of these studies have been focused on single static temperatures instead of evaluating thermal tolerance in a wide range of stressful temperatures. Additionally, there is evidence supporting that the gut microbiota is sensitive to environmental temperature, which induces changes in its composition and diversity. These studies have evaluated the effects of thermal acclimation (&gt;2 weeks) on the gut microbiota, but we know little about the impact of transient thermal stress on the composition and diversity of the gut microbiota. Thus, we investigated the role of the gut microbiota on the heat tolerance of Drosophila subobscura by measuring the heat tolerance of conventional and axenic flies exposed to different heat stressful temperatures (35, 36, 37, and 38°C) and estimating the heat tolerance landscape for both microbiota treatments. Conventional flies exposed to mild heat conditions exhibited higher thermal tolerance than axenic flies, whereas at higher stressful temperatures there were no differences between axenic and conventional flies. We also assessed the impact of transient heat stress on the taxonomical abundance, diversity, and community structure of the gut microbiota, comparing non-stressed flies (exposed to 21°C) and heat-stressed flies (exposed to 34°C) from both sexes. Bacterial diversity indices, bacterial abundances, and community structure changed between non-stressed and heat-stressed flies, and this response was sex-dependent. In general, our findings provide evidence that the gut microbiota influences heat tolerance and that heat stress modifies the gut microbiota at the taxonomical and structural levels. These results demonstrate that the gut microbiota contributes to heat tolerance and is also highly sensitive to transient heat stress, which could have important consequences on host fitness, population risk extinction, and the vulnerability of ectotherms to current and future climatic conditions.

scholarly journals Molecular Chaperones in the Yeast Endoplasmic Reticulum Maintain the Solubility of Proteins for Retrotranslocation and Degradation

2001 ◽  
Vol 153 (5) ◽  
pp. 1061-1070 ◽  
Author(s):  
Shuh-ichi Nishikawa ◽  
Sheara W. Fewell ◽  
Yoshihito Kato ◽  
Jeffrey L. Brodsky ◽  
Toshiya Endo
Keyword(s):  
Endoplasmic Reticulum ◽  
Molecular Chaperone ◽  
Molecular Chaperones ◽  
Elevated Temperatures ◽  
Carboxypeptidase Y ◽  
Mutant Form ◽  
Genes Encoding

Endoplasmic reticulum (ER)-associated degradation (ERAD) is the process by which aberrant proteins in the ER lumen are exported back to the cytosol and degraded by the proteasome. Although ER molecular chaperones are required for ERAD, their specific role(s) in this process have been ill defined. To understand how one group of interacting lumenal chaperones facilitates ERAD, the fates of pro–α-factor and a mutant form of carboxypeptidase Y were examined both in vivo and in vitro. We found that these ERAD substrates are stabilized and aggregate in the ER at elevated temperatures when BiP, the lumenal Hsp70 molecular chaperone, is mutated, or when the genes encoding the J domain–containing proteins Jem1p and Scj1p are deleted. In contrast, deletion of JEM1 and SCJ1 had little effect on the ERAD of a membrane protein. These results suggest that one role of the BiP, Jem1p, and Scj1p chaperones is to maintain lumenal ERAD substrates in a retrotranslocation-competent state.

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