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.

scholarly journals Analysis of Nitrogenase Fe Protein Activity in Transplastomic Tobacco

2021 ◽  
Vol 3 ◽  
Author(s):  
Jose A. Aznar-Moreno ◽  
Xi Jiang ◽  
Stefan Burén ◽  
Luis M. Rubio
Keyword(s):  
Plastid Genome ◽  
Elevated Temperatures ◽  
Specific Activity ◽  
Constitutive Expression ◽  
Yeast Cells ◽  
Nitrogen Fertilizers ◽  
Protein Activity ◽  
Transplastomic Plants ◽  
Fe Protein

Integration of prokaryotic nitrogen fixation (nif) genes into the plastid genome for expression of functional nitrogenase components could render plants capable of assimilating atmospheric N2 making their crops less dependent of nitrogen fertilizers. The nitrogenase Fe protein component (NifH) has been used as proxy for expression and targeting of Nif proteins within plant and yeast cells. Here we use tobacco plants with the Azotobacter vinelandii nifH and nifM genes integrated into the plastid genome. NifH and its maturase NifM were constitutively produced in leaves, but not roots, during light and dark periods. Nif protein expression in transplastomic plants was stable throughout development. Chloroplast NifH was soluble, but it only showed in vitro activity when isolated from leaves collected at the end of the dark period. Exposing the plant extracts to elevated temperatures precipitated NifM and apo-NifH protein devoid of [Fe4S4] clusters, dramatically increasing the specific activity of remaining NifH protein. Our data indicate that the chloroplast endogenous [Fe-S] cluster biosynthesis was insufficient for complete NifH maturation, albeit a negative effect on NifH maturation due to excess NifM in the chloroplast cannot be excluded. NifH and NifM constitutive expression in transplastomic plants did not affect any of the following traits: seed size, germination time, germination ratio, seedling growth, emergence of the cotyledon and first leaves, chlorophyll content and plant height throughout development.

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 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.

Sectioned rubisco crystals in TEM

1990 ◽  
Vol 48 (3) ◽  
pp. 664-665
Author(s):  
Gunnel Karlsson ◽  
Jan-Olov Bovin ◽  
Michael Bosma
Keyword(s):  
Plant Cell ◽  
Carbon Fixation ◽  
Unit Cell ◽  
Protein Crystals ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Photosynthetic Carbon Fixation ◽  
Photosynthetic Carbon

RuBisCO (D-ribulose-l,5-biphosphate carboxylase/oxygenase) is the most aboundant enzyme in the plant cell and it catalyses the key carboxylation reaction of photosynthetic carbon fixation, but also the competing oxygenase reaction of photorespiation. In vitro crystallized RuBisCO has been studied earlier but this investigation concerns in vivo existance of RuBisCO crystals in anthers and leaves ofsugarbeets. For the identification of in vivo protein crystals it is important to be able to determinethe unit cell of cytochemically identified crystals in the same image. In order to obtain the best combination of optimal contrast and resolution we have studied different staining and electron accelerating voltages. It is known that embedding and sectioning can cause deformation and obscure the unit cell parameters.

Effect of Temperature, Velocity Gradient and I.V. Heparin on in Vitro Blood Coagulation and Platelet Aggregation

1967 ◽  
Vol 17 (01/02) ◽  
pp. 112-119 ◽  
Author(s):  
L Dintenfass ◽  
M. C Rozenberg
Keyword(s):  
Blood Coagulation ◽  
Velocity Gradient ◽  
Elevated Temperatures ◽  
Morphological Changes ◽  
Effect Of Temperature ◽  
Clotting Time ◽  
Progressive Change ◽  
Aggregation Of Platelets ◽  
Microscopic Techniques

SummaryA study of blood coagulation was carried out by observing changes in the blood viscosity of blood coagulating in the cone-in-cone viscometer. The clots were investigated by microscopic techniques.Immediately after blood is obtained by venepuncture, viscosity of blood remains constant for a certain “latent” period. The duration of this period depends not only on the intrinsic properties of the blood sample, but also on temperature and rate of shear used during blood storage. An increase of temperature decreases the clotting time ; also, an increase in the rate of shear decreases the clotting time.It is confirmed that morphological changes take place in blood coagula as a function of the velocity gradient at which such coagulation takes place. There is a progressive change from the red clot to white thrombus as the rates of shear increase. Aggregation of platelets increases as the rate of shear increases.This pattern is maintained with changes of temperature, although aggregation of platelets appears to be increased at elevated temperatures.Intravenously added heparin affects the clotting time and the aggregation of platelets in in vitro coagulation.

Exogenous phospholipase A2 affects inflammatory gene expression in primary bovine mammary epithelial cells

2019 ◽  
Vol 86 (2) ◽  
pp. 177-180
Author(s):  
Jacqueline P. Kurz ◽  
Mark P. Richards ◽  
Matthew Garcia ◽  
Zhongde Wang
Keyword(s):  
Epithelial Cells ◽  
Phospholipase A2 ◽  
Inflammatory Responses ◽  
Mammary Epithelial Cells ◽  
Constitutive Expression ◽  
Mammary Epithelial ◽  
Inflammatory Factors ◽  
Bovine Mammary Epithelial Cells ◽  
Lps Challenge

AbstractThis Research Communication addresses the hypothesis that exogenously administered phospholipase A2 (PLA2) affects the inflammatory responses of bovine mammary epithelial cells (bMEC) in vitro with the aim of providing preliminary justification of investigation into the uses of exogenously administered PLA2 to manage or treat bovine mastitis. Primary bMEC lines from 11 lactating Holstein dairy cows were established and the expression of 14 pro-inflammatory genes compared under unchallenged and lipopolysaccharide (LPS)-challenged conditions, with and without concurrent treatment with bovine pancreatic PLA2G1B, a secreted form of PLA2. No differences in the expression of these genes were noted between PLA2-treated and untreated bMEC under unchallenged conditions. Following LPS challenge, untreated bMEC exhibited significant downregulation of CXCL8, IL1B, CCL20, and CXCL1. In contrast, PLA2-treated bMEC exhibited significant downregulation of IL1B and CCL20 only. These findings indicate that exogenous PLA2 affects the expression of some pro-inflammatory factors in immune-stimulated bMEC, but does not influence the constitutive expression of these factors. Further investigation of the influence of exogenous PLA2 in the bovine mammary gland is justified.

scholarly journals Hsp90 Binds and Regulates the Ligand-Inducible α Subunit of Eukaryotic Translation Initiation Factor Kinase Gcn2

1999 ◽  
Vol 19 (12) ◽  
pp. 8422-8432 ◽  
Author(s):  
Olivier Donzé ◽  
Didier Picard
Keyword(s):  
Amino Acid ◽  
Constitutive Expression ◽  
Amino Acid Starvation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Restrictive Temperature ◽  
Α Subunit ◽  
Macbecin I

ABSTRACT The protein kinase Gcn2 stimulates translation of the yeast transcription factor Gcn4 upon amino acid starvation. Using genetic and biochemical approaches, we show that Gcn2 is regulated by the molecular chaperone Hsp90 in budding yeast Saccharomyces cerevisiae. Specifically, we found that (i) several Hsp90 mutant strains exhibit constitutive expression of a GCN4-lacZ reporter plasmid; (ii) Gcn2 and Hsp90 form a complex in vitro as well as in vivo; (iii) the specific inhibitors of Hsp90, geldanamycin and macbecin I, enhance the association of Gcn2 with Hsp90 and inhibit its kinase activity in vitro; (iv) in vivo, macbecin I strongly reduces the levels of Gcn2; (v) in a strain expressing the temperature-sensitive Hsp90 mutant G170D, both the accumulation and activity of Gcn2 are abolished at the restrictive temperature; and (vi) the Hsp90 cochaperones Cdc37, Sti1, and Sba1 are required for the response to amino acid starvation. Taken together, these data identify Gcn2 as a novel target for Hsp90, which plays a crucial role for the maturation and regulation of Gcn2.

scholarly journals R-BPMV-Mediated Resistance to Bean pod mottle virus in Phaseolus vulgaris L. Is Heat-Stable but Elevated Temperatures Boost Viral Infection in Susceptible Genotypes

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1239
Author(s):  
Chouaïb Meziadi ◽  
Julie Lintz ◽  
Masoud Naderpour ◽  
Charlotte Gautier ◽  
Sophie Blanchet ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Phaseolus Vulgaris ◽  
Elevated Temperatures ◽  
Heat Waves ◽  
Dominant Gene ◽  
Atmospheric Temperature ◽  
Mottle Virus ◽  
Bean Pod Mottle Virus ◽  
Heat Stable ◽  
The Impact

In the context of climate change, elevated temperature is a major concern due to the impact on plant–pathogen interactions. Although atmospheric temperature is predicted to increase in the next century, heat waves during summer seasons have already become a current problem. Elevated temperatures strongly influence plant–virus interactions, the most drastic effect being a breakdown of plant viral resistance conferred by some major resistance genes. In this work, we focused on the R-BPMV gene, a major resistance gene against Bean pod mottle virus in Phaseolus vulgaris. We inoculated different BPMV constructs in order to study the behavior of the R-BPMV-mediated resistance at normal (20 °C) and elevated temperatures (constant 25, 30, and 35 °C). Our results show that R-BPMV mediates a temperature-dependent phenotype of resistance from hypersensitive reaction at 20 °C to chlorotic lesions at 35 °C in the resistant genotype BAT93. BPMV is detected in inoculated leaves but not in systemic ones, suggesting that the resistance remains heat-stable up to 35 °C. R-BPMV segregates as an incompletely dominant gene in an F2 population. We also investigated the impact of elevated temperature on BPMV infection in susceptible genotypes, and our results reveal that elevated temperatures boost BPMV infection both locally and systemically in susceptible genotypes.

THE INTERACTION OF ENZYMES AND HORMONES

PEDIATRICS ◽  
1960 ◽  
Vol 26 (3) ◽  
pp. 476-481
Author(s):  
Abraham White
Keyword(s):  
Direct Effect ◽  
Chemical Reactions ◽  
Elevated Temperatures ◽  
Enzyme System ◽  
Enzymic Activity ◽  
Hormone Interaction ◽  
Indirect Influence ◽  
Rare Exception ◽  
Hormonal Action

The majority of living forms depend for their functioning upon two classes of biocatalysts, the enzymes and the hormones. These biocatalysts permit the diverse chemical reactions of the organism to proceed at 38°C with a specificity and at rates frequently unattainable in vitro at elevated temperatures with similar reactants. The physiologic importance of enzymes and hormones is evident not only under normal circumstances, but is reflected clinically in the diverse descriptions of errors of metabolism, due to lack or deficiency of one or more enzymes, and the numerous hypo- and hyperfunctioning states resulting from imbalance of hormonal supply. Inasmuch as both enzymes and hormones function, with rare exception, to accelerate the rates of processes in cells, investigators have sought possible interrelationships and interactions of enzymes and hormones, particularly as a basis for the mechanism of hormonal action. It has seemed logical to hypothesize that hormones, while not essential for reactions to proceed but nevertheless affecting the rates of reactions, may function by altering either the concentration or activity of the prime cellular catalysts, the enzymes. This proposed influence of hormones on enzymic activity might be a primary, direct effect achieved by the hormone participating as an integral part of an enzyme system, or an indirect influence based upon the hormone altering the concentration of available enzyme and/or substrate utilized by a particular enzyme. It is the purpose of this presentation to describe a relatively few, but better defined, examples of the more direct relationships of enzymes and hormones. Five examples of enzyme-hormone interaction will be presented, based on the criterion that an effect of the hormone has been demonstrated on addition of the hormone in vitro to a purifled, or partially purified, enzyme system.

scholarly journals Thermal tolerance of the zoea I stage of four Neotropical crab species (Crustacea: Decapoda)

2018 ◽  
Vol 35 ◽  
pp. 1-5
Author(s):  
Adriana P. Rebolledo ◽  
Rachel Collin
Keyword(s):  
Thermal Tolerance ◽  
Elevated Temperatures ◽  
Marine Invertebrates ◽  
Negative Impact ◽  
Larval Survival ◽  
Crab Species ◽  
Marine Habitat ◽  
Mangrove Species ◽  
Larval Stages ◽  
Carry Over

. Although larval stages are often considered particularly vulnerable to stressors, for many marine invertebrates studies of thermal tolerance have focused on adults. Here we determined the upper thermal limit (LT50) of the zoea I of four Caribbean crab species (Macrocoelomatrispinosum, Aratuspisonii, Armasesricordi, and Minucarapax) and compared their thermal tolerance over time and among species. The zoea from the subtidal species M.trispinosum and tree climbing mangrove species A.pisonii had a lower thermal tolerance, 35 and 38.5 °C respectively, than did the semiterrestrial A.ricordi and M.rapax. In all four species tested, the estimates of thermal tolerance depend on the duration of exposure to elevated temperatures. Longer exposures to thermal stress produce lower estimates of LT50, which decreased by ~1 °C from a two- to a six-hour exposure. Crab embryos develop on the abdomen of the mother until the larvae are ready to hatch. Therefore, the thermal tolerances of the embryos which need to coincide with the environmental conditions experienced by the adult stage, may carry over into the early zoea stage. Our results suggest that semiterrestrial species, in which embryos may need to withstand higher temperatures than embryos of subtidal species also produce larvae with higher thermal tolerances. Over the short term, the larvae of these tropical crab species can withstand significantly higher temperatures than those experienced in their marine habitat. Longer term rearing studies are necessary to determine the temperature at which chronic exposure has a negative impact on embryonic and larval survival.

Sign in / Sign up

Export Citation Format

Share Document