scholarly journals Osmoregulation and the Anthozoan-Dinoflagellate Symbiosis

2021 ◽  
Author(s):  
◽  
Michael Cowlin
Keyword(s):  
Osmotic Stress ◽  
Stress Responses ◽  
High Performance ◽  
Stable State ◽  
Organic Osmolytes ◽  
Physiological Indicators ◽  
Host Cytoplasm ◽  
Saline Treatment ◽  
Tropical Coral ◽  
Osmotic Treatment

<p>This study investigated the responses of the temperate anemone Anthopleura aureoradiata, and the tropical coral Acropora aspera to osmotic stress and the role that free amino acids (FAAs) may play in the osmoregulatory mechanism of these anthozoan-dinoflagellate symbioses. Specimens were exposed to a range of hypo- and hyper-saline conditions for durations of 1, 12, 48 and 96 hours, whereupon respiration and photosynthetic rates were measured as physiological indicators of osmotic stress. High performance liquid chromatography was used to quantify 15 FAAs within the anthozoan host tissues to establish the response of FAA pools to osmotic stress and whether FAAs are used in an osmoregulatory capacity. Aposymbiotic specimens of A. aureoradiata were similarly tested to establish if the presence of symbiotic dinoflagellates alters the host’s capacity to respond to osmotic stress given that the symbionts are known to release FAAs into the host cytoplasm. In A. aureoradiata, significant changes in respiration were only observed with exposure to the extreme hypo-osmotic salinity of 12‰, with respiration decreasing by 67% after 1 hour of exposure. No significant changes in respiration were seen at 25, 43 or 50‰, despite a 52% decrease in respiration seen at the hyper-saline treatment of 50‰. The response of the coral A. aspera was markedly different, showing an increase in respiration in response to hypo-salinity (22 and 28‰). Interestingly, the most pronounced respiratory increase of up to 460% occurred in the less extreme hypo-saline treatment of 28‰. The response of photosynthesis also showed differences between the two species. In the symbiotic A. aureoradiata, photosynthesis declined by 61% after the 1 hour exposure to 12‰ and further decreased to 72% below control rates after 96 hours. While in A. aspera, photosynthesis showed no significant deviation from control levels at any of the treatment salinities. FAA pools in both A. aureoradiata and A. aspera showed significant responses to osmotic stress. In symbiotic A. aureoradiata, exposure to 12‰ caused total FAA pools to decline by 50% after 1 hour, after which a seemingly stable state was reached. A hyper-osmotic treatment of 50‰ resulted in a similar trend with a more than 50% decrease after 1 hour of exposure. In A. aspera, the response of the FAA pool was markedly different, with the concentration increasing by up to 200% with exposure to 22‰ and by more than 260% at 28‰. Interestingly, one on the main constituents of FAA pools in A. aureoradiata, Taurine (15% of FAA pools at 35‰), was not present in measurable quantities within A. aspera host tissue. In aposymbiotic individuals of A. aureoradiata exposed to extreme hypo- and hyper-saline treatments of 12 and 50‰ a significant impact on respiration was only observed at 12‰, with a 77% decrease in respiration after 96 hours. Changes in FAA pools of aposymbiotic A. aureoradiata were only seen after 12 hours exposure to 50‰ with a significant 26% decrease. However, the direct comparison between symbiotic and aposymbiotic A. aureoradiata did serve to highlight the contribution of symbiont-derived FAAs to the host pool of FAAs, with FAA pools in aposymbiotic anemones up to 41% lower than those found in symbiotic anemones. The results seen here were not suggestive of FAAs being regulated for the explicit use as compatible organic osmolytes. Rather, changes in FAA pools showed changes consistent with other stress responses. Moreover, the response of anthozoan-dinoflagellate symbioses to osmotic stress appears to be species specific, or at least taxa specific, as the responses of respiration, photosynthesis and FAA pools were very different between the temperate anemone A. aureoradiata and the tropical coral A. aspera. Nevertheless, differences in the respiratory response between symbiotic and apo-symbiotic anemones did indicate some influence of the dinoflagellate symbionts on the ability of the anthozoan host to mediate osmotic stress. It may therefore be that other symbiont-derived compounds are utilised as compatible organic osmolytes (COOs), with a primary candidate being glycerol. This warrants further investigation.</p>

scholarly journals Osmoregulation and the Anthozoan-Dinoflagellate Symbiosis

2021 ◽  
Author(s):  
◽  
Michael Cowlin
Keyword(s):  
Osmotic Stress ◽  
Stress Responses ◽  
High Performance ◽  
Stable State ◽  
Organic Osmolytes ◽  
Physiological Indicators ◽  
Host Cytoplasm ◽  
Saline Treatment ◽  
Tropical Coral ◽  
Osmotic Treatment

<p>This study investigated the responses of the temperate anemone Anthopleura aureoradiata, and the tropical coral Acropora aspera to osmotic stress and the role that free amino acids (FAAs) may play in the osmoregulatory mechanism of these anthozoan-dinoflagellate symbioses. Specimens were exposed to a range of hypo- and hyper-saline conditions for durations of 1, 12, 48 and 96 hours, whereupon respiration and photosynthetic rates were measured as physiological indicators of osmotic stress. High performance liquid chromatography was used to quantify 15 FAAs within the anthozoan host tissues to establish the response of FAA pools to osmotic stress and whether FAAs are used in an osmoregulatory capacity. Aposymbiotic specimens of A. aureoradiata were similarly tested to establish if the presence of symbiotic dinoflagellates alters the host’s capacity to respond to osmotic stress given that the symbionts are known to release FAAs into the host cytoplasm. In A. aureoradiata, significant changes in respiration were only observed with exposure to the extreme hypo-osmotic salinity of 12‰, with respiration decreasing by 67% after 1 hour of exposure. No significant changes in respiration were seen at 25, 43 or 50‰, despite a 52% decrease in respiration seen at the hyper-saline treatment of 50‰. The response of the coral A. aspera was markedly different, showing an increase in respiration in response to hypo-salinity (22 and 28‰). Interestingly, the most pronounced respiratory increase of up to 460% occurred in the less extreme hypo-saline treatment of 28‰. The response of photosynthesis also showed differences between the two species. In the symbiotic A. aureoradiata, photosynthesis declined by 61% after the 1 hour exposure to 12‰ and further decreased to 72% below control rates after 96 hours. While in A. aspera, photosynthesis showed no significant deviation from control levels at any of the treatment salinities. FAA pools in both A. aureoradiata and A. aspera showed significant responses to osmotic stress. In symbiotic A. aureoradiata, exposure to 12‰ caused total FAA pools to decline by 50% after 1 hour, after which a seemingly stable state was reached. A hyper-osmotic treatment of 50‰ resulted in a similar trend with a more than 50% decrease after 1 hour of exposure. In A. aspera, the response of the FAA pool was markedly different, with the concentration increasing by up to 200% with exposure to 22‰ and by more than 260% at 28‰. Interestingly, one on the main constituents of FAA pools in A. aureoradiata, Taurine (15% of FAA pools at 35‰), was not present in measurable quantities within A. aspera host tissue. In aposymbiotic individuals of A. aureoradiata exposed to extreme hypo- and hyper-saline treatments of 12 and 50‰ a significant impact on respiration was only observed at 12‰, with a 77% decrease in respiration after 96 hours. Changes in FAA pools of aposymbiotic A. aureoradiata were only seen after 12 hours exposure to 50‰ with a significant 26% decrease. However, the direct comparison between symbiotic and aposymbiotic A. aureoradiata did serve to highlight the contribution of symbiont-derived FAAs to the host pool of FAAs, with FAA pools in aposymbiotic anemones up to 41% lower than those found in symbiotic anemones. The results seen here were not suggestive of FAAs being regulated for the explicit use as compatible organic osmolytes. Rather, changes in FAA pools showed changes consistent with other stress responses. Moreover, the response of anthozoan-dinoflagellate symbioses to osmotic stress appears to be species specific, or at least taxa specific, as the responses of respiration, photosynthesis and FAA pools were very different between the temperate anemone A. aureoradiata and the tropical coral A. aspera. Nevertheless, differences in the respiratory response between symbiotic and apo-symbiotic anemones did indicate some influence of the dinoflagellate symbionts on the ability of the anthozoan host to mediate osmotic stress. It may therefore be that other symbiont-derived compounds are utilised as compatible organic osmolytes (COOs), with a primary candidate being glycerol. This warrants further investigation.</p>

A versatile proline/alanine transporter in the unicellular pathogen Leishmania donovani regulates amino acid homoeostasis and osmotic stress responses

2012 ◽  
Vol 449 (2) ◽  
pp. 555-566 ◽  
Author(s):  
Ehud Inbar ◽  
Doreen Schlisselberg ◽  
Marianne Suter Grotemeyer ◽  
Doris Rentsch ◽  
Dan Zilberstein
Keyword(s):  
Amino Acid ◽  
Osmotic Stress ◽  
Stress Responses ◽  
Leishmania Donovani ◽  
Carbon Sources ◽  
Cell Volume Regulation ◽  
Organic Osmolytes ◽  
Neutral Amino Acid Transporter ◽  
The Family ◽  
Varying Environments

Unlike all other organisms, parasitic protozoa of the family Trypanosomatidae maintain a large cellular pool of proline that, together with the alanine pool, serve as alternative carbon sources as well as reservoirs of organic osmolytes. These reflect adaptation to their insect vectors whose haemolymphs are exceptionally rich in the two amino acids. In the present study we identify and characterize a new neutral amino acid transporter, LdAAP24, that translocates proline and alanine across the Leishmania donovani plasma membrane. This transporter fulfils multiple functions: it is the sole supplier for the intracellular pool of proline and contributes to the alanine pool; it is essential for cell volume regulation after osmotic stress; and it regulates the transport and homoeostasis of glutamate and arginine, none of which are its substrates. Notably, we provide evidence that proline and alanine exhibit different roles in the parasitic response to hypotonic shock; alanine affects swelling, whereas proline influences the rate of volume recovery. On the basis of our data we suggest that LdAAP24 plays a key role in parasite adaptation to its varying environments in host and vector, a phenomenon essential for successful parasitism.

scholarly journals Physiological and Psychological Effects of Watching Videos of Different Durations Showing Urban Bamboo Forests with Varied Structures

2020 ◽  
Vol 17 (10) ◽  
pp. 3434
Author(s):  
Yuqian Wang ◽  
Mingyan Jiang ◽  
Yinshu Huang ◽  
Zhiyi Sheng ◽  
Xiao Huang ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Skin Conductance ◽  
Human Body ◽  
Stable State ◽  
Mean Value ◽  
Psychological Effects ◽  
Physiological Indicators ◽  
Psychological Indicators ◽  
Before And After ◽  
Long Time

This study illustrated the physiological and psychological effects of watching videos of different durations showing bamboo forests with varied structures. Physiological indicators, including EEG (electroencephalogram), blood pressure, skin conductance, and pulse, were monitored in 180 Chinese university students (mean age: 20.72 ± 2.56 years) while they were watching bamboo videos. Before and after watching the videos, their psychological indicators, including positive and negative moods, were measured using the Profile of Mood States questionnaire. After watching the bamboo videos of different durations, all of the physiological indicators responded to the stimulation after only 1 min. The indicators showed different trends at 1, 3 and 5 min. EEG decreased and then was maintained at a stable level after 1 min, and the high β, low β, and α waves had no significant differences between 1, 3 and 5 min. Blood pressure dropped to a stable state after 3 min, and the decline was significantly different greater after 3 min than after 1 min. Skin conductance increased for 1 to 5 min, and it did not stabilize after a long time (5 min). Pulse decreased after 1 min but increased after 5 min. After watching the videos with bamboo of varying structures, the physiological and psychological indicators showed significantly different changes. Skin conductance significantly increased (mean value: 6.78%), and the amount of sweat was more effectively reduced, thereby reducing tension, when the students viewed videos of sympodial bamboo forests compared with monopodial bamboo forests. Bamboo forests with a higher canopy density (0.83–0.85) could significantly decrease α waves (mean value: 1.50 Hz), relaxing the human body. High β and low β waves showed greater decreases, with tension reduced more effectively, when bamboo forests with a low tilt ratio (< 1.5%) were viewed. Bamboo forests with neat undergrowth could have more beneficial physiological and psychological effects on the human body.

scholarly journals Osmotic Stress or Ionic Composition: Which Affects the Early Growth of Crop Species More?

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 435
Author(s):  
Agnieszka Ludwiczak ◽  
Monika Osiak ◽  
Stefany Cárdenas-Pérez ◽  
Sandra Lubińska-Mielińska ◽  
Agnieszka Piernik
Keyword(s):  
Osmotic Stress ◽  
Stress Responses ◽  
Ionic Composition ◽  
Degradation Process ◽  
Early Growth ◽  
Cultivated Plants ◽  
C3 Plants ◽  
Growth Stages ◽  
Crop Species ◽  
Ionic Salt

Salinization is a key soil degradation process. An estimated 20% of total cultivated lands and 33% of irrigated agricultural lands worldwide are affected by high salinity. Much research has investigated the influence of salt (mainly NaCl) on plants, but very little is known about how this is related to natural salinity and osmotic stress. Therefore, our study was conducted to determine the osmotic and ionic salt stress responses of selected C3 and C4 cultivated plants. We focused on the early growth stages as those critical for plant development. We applied natural brine to simulate natural salinity and to compare its effect to NaCl solution. We assessed traits related to germination ability, seedlings and plantlet morphology, growth indexes, and biomass and water accumulation. Our results demonstrate that the effects of salinity on growth are strongest among plantlets. Salinity most affected water absorption in C3 plants (28% of total traits variation), but plant length in C4 plants (17–27%). Compensatory effect of ions from brine were suggested by the higher model plants’ growth success of ca 5–7% under brine compared to the NaCl condition. However, trait differences indicated that osmotic stress was the main stress factor affecting the studied plants.

scholarly journals Screening for Osmotic Stress Responses in Rice Varieties under Drought Condition

Rice Science ◽  
2017 ◽  
Vol 24 (5) ◽  
pp. 253-263 ◽  
Author(s):  
Simon Swapna ◽  
Korukkanvilakath Samban Shylaraj
Keyword(s):  
Osmotic Stress ◽  
Stress Responses ◽  
Drought Condition ◽  
Rice Varieties

scholarly journals Activated Expression of PHT Genes Contributes to Osmotic Stress Resistance under Low Phosphorus Levels in Malus

2018 ◽  
Vol 143 (6) ◽  
pp. 436-445
Author(s):  
Tingting Sun ◽  
Tingting Pei ◽  
Zhijun Zhang ◽  
Mingjun Li ◽  
Linlin Huang ◽  
...  
Keyword(s):  
Osmotic Stress ◽  
Stress Resistance ◽  
Molecular Mechanisms ◽  
Photosynthetic Parameters ◽  
Plant Responses ◽  
Malus Prunifolia ◽  
Physiological Indicators ◽  
Malus Sieversii ◽  
Low Phosphorus ◽  
Osmotic Stress Resistance

Osmotic adjustments play a fundamental role in plant responses to water deficit. For apple (Malus domestica) trees growing in the primary production areas of China, drought and low phosphorus (P) levels are the main sources of abiotic stress. Although tolerance to drought and low P are important breeding goals for cultivar improvement, there is little information on natural variation within Malus for these traits or the molecular mechanisms that may mediate tolerance. In this study, it was found that in plants grown under conditions of osmotic and low P stress, electrolyte leakage and photosynthetic parameters were significantly higher, but chlorophyll concentrations were lower compared with nonstressed plants. These physiological indicators revealed that, under low P condition, the order of osmotic stress resistance (high to low) was Malus sieversii (Ms) → Malus prunifolia (Mp) → Malus hupehensis (Mh). Expression of the phosphorus transporter genes PHT1;7, PHT1;12, and PHT2;1 in the roots and PHT1;12 and PHT4;5 in the leaves was positively correlated with plant osmotic resistance. It is proposed that the highly expressed PHT genes might improve P absorption and transport efficiency, resulting in the high osmotic stress resistance under low P level conditions in Malus species.

scholarly journals Implementation on the dSPACE 1104 of VOC-SVM based anti-windup PI Controller of a three-phase PWM rectifier

2021 ◽  
Vol 12 (3) ◽  
pp. 1586
Author(s):  
J. Lamterkati ◽  
L. Ouboubker ◽  
M. Khafallah ◽  
A. El afia
Keyword(s):  
High Performance ◽  
Pulse Width Modulation ◽  
Control Method ◽  
Stable State ◽  
Switching Frequency ◽  
Pwm Rectifier ◽  
External Loop ◽  
Three Phase ◽  
Dspace 1104 ◽  
Controller Board

<p><span>The study made in this paper concerns the use of the voltage-oriented control (VOC) of three-phase pulse width modulation (PWM) rectifier with constant switching frequency. This control method, called voltage-oriented controlwith space vector modulation (VOC-SVM). The proposed control scheme has been founded on the transformation between stationary (α-β) and and synchronously rotating (d-q) coordinate system, it is based on two cascaded control loops so that a fast inner loop controls the grid current and an external loop DC-link voltage, while the DC-bus voltage is maintained at the desired level and ansured the unity power factor operation. So, the stable state performance and robustness against the load’s disturbance of PWM rectifiers are boths improved. The proposed scheme has been implemented and simulated in MATLAB/Simulink environment. The control system of the VOC-SVM strategy has been built based on dSPACE system with DS1104 controller board. The results obtained show the validity of the model and its control method. Compared with the conventional SPWM method, the VOC-SVM ensures high performance and fast transient response.</span></p>

scholarly journals The build-up of osmotic stress responses within the growing root apex using kinematics and RNA-sequencing

2016 ◽  
Vol 67 (21) ◽  
pp. 5961-5973 ◽  
Author(s):  
Mathilde Royer ◽  
David Cohen ◽  
Nathalie Aubry ◽  
Vera Vendramin ◽  
Simone Scalabrin ◽  
...  
Keyword(s):  
Osmotic Stress ◽  
Rna Sequencing ◽  
Stress Responses ◽  
Root Apex

scholarly journals High-Level Expression, Purification and Initial Characterization of Recombinant Arabidopsis Histidine Kinase AHK1

Plants ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 304 ◽  
Author(s):  
Alexander Hofmann ◽  
Sophia Müller ◽  
Thomas Drechsler ◽  
Mareike Berleth ◽  
Katharina Caesar ◽  
...  
Keyword(s):  
Osmotic Stress ◽  
Stress Responses ◽  
Histidine Kinase ◽  
Degradation Products ◽  
Polyacrylamide Gel Electrophoresis ◽  
Gel Filtration ◽  
Cd Spectroscopy ◽  
Single Step ◽  
Signaling Mechanism ◽  
Wide Range

Plants employ a number of phosphorylation cascades in response to a wide range of environmental stimuli. Previous studies in Arabidopsis and yeast indicate that histidine kinase AHK1 is a positive regulator of drought and osmotic stress responses. Based on these studies AHK1 was proposed a plant osmosensor, although the molecular basis of plant osmosensing still remains unknown. To understand the molecular role and signaling mechanism of AHK1 in osmotic stress, we have expressed and purified full-length AHK1 from Arabidopsis in a bacterial host to allow for studies on the isolated transmembrane receptor. Purification of the recombinant protein solubilized from the host membranes was achieved in a single step by metal-affinity chromatography. Analysis of the purified AHK1 by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting show a single band indicating that the preparation is highly pure and devoid of contaminants or degradation products. In addition, gel filtration experiments indicate that the preparation is homogenous and monodisperse. Finally, CD-spectroscopy, phosphorylation activity, dimerization studies, and protein–protein interaction with plant phosphorylation targeting AHP2 demonstrate that the purified protein is functionally folded and acts as phospho-His or phospho-Asp phosphatase. Hence, the expression and purification of recombinant AHK1 reported here provide a basis for further detailed functional and structural studies of the receptor, which might help to understand plant osmosensing and osmosignaling on the molecular level.

scholarly journals Plant growth under suboptimal water conditions: early responses and methods to study them

2020 ◽  
Vol 71 (5) ◽  
pp. 1706-1722 ◽  
Author(s):  
Marieke Dubois ◽  
Dirk Inzé
Keyword(s):  
Plant Growth ◽  
Osmotic Stress ◽  
Stress Responses ◽  
Soil Drought ◽  
Growth Media ◽  
Plant Responses ◽  
Short Term ◽  
Environmental Constraint ◽  
Early Stress ◽  
Different Types

Abstract Drought stress forms a major environmental constraint during the life cycle of plants, often decreasing plant yield and in extreme cases threatening survival. The molecular and physiological responses induced by drought have been the topic of extensive research during the past decades. Because soil-based approaches to studying drought responses are often challenging due to low throughput and insufficient control of the conditions, osmotic stress assays in plates were developed to mimic drought. Addition of compounds such as polyethylene glycol, mannitol, sorbitol, or NaCl to controlled growth media has become increasingly popular since it offers the advantage of accurate control of stress level and onset. These osmotic stress assays enabled the discovery of very early stress responses, occurring within seconds or minutes following osmotic stress exposure. In this review, we construct a detailed timeline of early responses to osmotic stress, with a focus on how they initiate plant growth arrest. We further discuss the specific responses triggered by different types and severities of osmotic stress. Finally, we compare short-term plant responses under osmotic stress versus in-soil drought and discuss the advantages, disadvantages, and future of these plate-based proxies for drought.

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