scholarly journals Cold-induced switch in direction of chloroplast relocation occurs independently of changes in endogenous phototropin expression

2019 ◽  
Author(s):  
Yuta Fujii ◽  
Yuka Ogasawara ◽  
Yamato Takahashi ◽  
Momoko Sakata ◽  
Saori Tamura ◽  
...  
Keyword(s):  
Light Intensity ◽  
Avoidance Response ◽  
Cold Treatment ◽  
Marchantia Polymorpha ◽  
Strong Light ◽  
Weak Light ◽  
Chloroplast Relocation ◽  
Induced Changes ◽  
Light Avoidance ◽  
The Relationship

AbstractWhen exposed to fluctuating light intensity, chloroplasts move towards weak light (accumulation response), and away from strong light (avoidance response). In addition, cold treatment (5°C) induces the avoidance response even under weak light conditions (cold-avoidance response). These three responses are mediated by the phototropin (phot), which is a blue-light photoreceptor and has also been found to act as a thermosensory protein that perceives temperature variation. Our previous report indicated that cold-induced changes in phot biochemical activity initiate the cold-avoidance response. In this study, we further explored the induction mechanism of the cold-avoidance response in the liverwort Marchantia polymorpha and examined the relationship between changes in the amount of phot and the induction of the cold-avoidance response. The switch between the accumulation and avoidance responses occurs at a so-called ‘transitional’ light intensity. Our physiological experiments revealed that a cold-mediated decrease in the transitional light intensity leads to the induction of the cold-avoidance response. While artificial overexpression of phot decreased the transitional light intensity as much as cold treatment did, the amount of endogenous phot remained unchanged by cold treatment in wild-type M. polymorpha. Taken together, these findings show that the cold-avoidance response is initiated by a cold-mediated reduction of the transitional light intensity, independent of the amount of endogenous phot. This study provides a clue to understand the mechanism underlying the switch in direction of chloroplast relocation in response to light and temperature.

scholarly journals THE LEIOGNATHIDAE (TELEOSTS): AN HYPOTHESIS RELATING THEIR MEAN DEPTH OCCURRENCE TO THE INTENSITY OF THEIR COUNTERSHADING BIOLUMINESCENCE

2018 ◽  
Vol 19 ◽  
pp. 137-146 ◽  
Author(s):  
Daniel Pauly
Keyword(s):  
Light Intensity ◽  
Shallow Water ◽  
Quantitative Data ◽  
Incident Light ◽  
Diffuse Light ◽  
Strong Light ◽  
The Family ◽  
Weak Light ◽  
The Mean ◽  
Ranking Order

All species belonging to the Family Leiognathidae (genera Leiognathus, Secutor & Gazza) are bioluminescent. They emit during daytime a downward, diffuse light which tends to disrupt their silhouette, making them less discernible from beneath to potential predators. It is here assumed that the intensity of light emitted should correspond to the intensity of incident light at the depth at which each species generally occurs. Using published information on the relative intensity of emitted light in different species and quantitative data on the mean depth occurrence of the species, it is shown that there is a good correspondance in the ranking order of both light intensity and depth occurrence in five species (e.g. Secutor ruconius emits a strong light and occurs in shallow water; Leiognathus elongatus emits a weak light and occurs at greater depth). Species not fitting into this pattern (e.g. Leiognathus splendens emits a weak light but occurs in very shallow water) tend to occur in murky water, where less light is required for counterillumination.

scholarly journals Comparison of left ventricle mechanical dyssynchrony parameters in ischemic and non-ischemic patients using 13N-NH3 PET/CT

2021 ◽  
Author(s):  
Angelica Mazzoletti ◽  
Domenico Albano ◽  
Francesco Bertagna ◽  
Claudio Tinoco Mesquita ◽  
Raffaele Giubbini
Keyword(s):  
Myocardial Necrosis ◽  
Mechanical Dyssynchrony ◽  
Left Ventricular ◽  
Ischemic Group ◽  
Pet Ct ◽  
Left Ventricular Mechanical Dyssynchrony ◽  
Perfusion Defects ◽  
Induced Changes ◽  
The Relationship ◽  
Post Stress

Abstract Background-Aim The relationship between perfusion pattern and stress-induced changes in Left Ventricular Mechanical Dyssynchrony (LVMD) has been previously described with controversial results using stress-rest perfusion imaging studies. The aim of this study was to assess the relationship between perfusion pattern and stress-induced changes in LVMD usingo regadenoson/rest13N-NH3 PET/CT. Methods There were 74 patients who underwent stress-rest 13N-NH PET/CT from January 2014 to October 2018 excluding patients with left bundle branch block, ventricular pacing and myocardial necrosis. The patients were divided into those with reversible perfusion defects at stress (Ischemic group, n = 18) and patients without reversible perfusion defects (non-ischemic group, n = 56). The LVMD parameters included: phase standard deviation (PSD) and phase histogram bandwidth (PHB), after stress and at rest. The ΔPSD (post-stressPSD-restPSD) and ΔPHB (post-stressPHB—restPHB) were calculated to measure stress-induced changes in LVMD. Results There were no significant differences in LVMD parameters between post-stress and at rest in both groups. The PSD post-stress, ΔPSD and PHB post-stress were significantly higher in the ischemic group. Conclusions Using a vasodilator as a stress, the PSD and PHB post-stress and ΔPSD were significantly higher in the ischemic patients than the non-ischemic group, while there were no significant differences in each cohort between stress and rest indices.

scholarly journals Response of Photosynthesis and Chlorophyll Fluorescence Parameters of Castanopsis kawakamii Seedlings to Forest Gaps

Forests ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 21
Author(s):  
Zhong-sheng He ◽  
Rong Tang ◽  
Meng-jia Li ◽  
Meng-ran Jin ◽  
Cong Xin ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Light Intensity ◽  
Seedling Growth ◽  
Group Treatment ◽  
Control Group ◽  
Low Light ◽  
Chlorophyll Fluorescence Parameters ◽  
Forest Gaps ◽  
Low Light Intensity ◽  
Weak Light

Light is a major environmental factor limiting the growth and survival of plants. The heterogeneity of the light environment after gap formation in forest influences the leaf chlorophyll contents, net photosynthetic rate (Pn), and chlorophyll fluorescence, thus influencing the growth and regeneration of Castanopsis kawakamii seedlings. The aim of this study was to explore the effects of weak light on the photosynthetic physiology of C. kawakamii seedlings in forest gaps and non-gaps. The results showed that (1) the contents of chlorophyll a (Chl-a), chlorophyll b (Chl-b), and total chlorophyll (Chl-T) in forest gaps were lower than in non-gaps. Seedlings tended to increase chlorophyll content to absorb light energy to adapt to low light intensity in non-gap environments. (2) The Pn values of C. kawakamii seedlings in forest gaps were significantly higher than in non-gaps, and forest gaps could improve the seedlings’ photosynthetic capacity. (3) The C. kawakamii seedlings in forest gaps were more sensitive to weak light and control group treatment, especially the tall seedlings, indicating that seedlings require more light to satisfy their growth needs in the winter. The seedlings in non-gaps demonstrated better adaptability to low light intensity. The light intensity was not adequate in weak light conditions and limited seedling growth. We suggest that partial forest selection cutting could improve light intensity in non-gaps, thus promoting seedling growth and regeneration of C. kawakamii more effectively in this forest.

CS Intensity, Amobarbital Sodium and the Conditioned Avoidance Response

1966 ◽  
Vol 18 (2) ◽  
pp. 645-646 ◽  
Author(s):  
Barbara J. Powell ◽  
M. E. Ogle ◽  
L. K. Martin ◽  
D. K. Kamano
Keyword(s):  
Avoidance Response ◽  
Avoidance Performance ◽  
Conditioned Avoidance ◽  
Conditioned Avoidance Response ◽  
Drug Condition ◽  
Marked Decline ◽  
Amobarbital Sodium ◽  
The Relationship ◽  
Better Than

In studying the relationship between level of CS intensity (light) and drug condition (amobarbital sodium) in the acquisition of the conditioned avoidance response of the white rat in a jump-box task, data showed that both variables influenced avoidance performance. Although the over-all performance of drugged Ss was better than that of those given a placebo, primary differences occurred at 50,000 and 800,000 peak candles of CS intensity; performance of Ss under placebo showed a marked decline at 800,000 peak candles.

Effect of light intensity on assimilation characteristics of detached tea leaves

1964 ◽  
Vol 63 (2) ◽  
pp. 265-271 ◽  
Author(s):  
D. N. Barua
Keyword(s):  
Light Intensity ◽  
Chlorophyll Concentration ◽  
Leaf Lamina ◽  
Tea Leaves ◽  
Tungsten Filament ◽  
Strong Light ◽  
Filament Lamp ◽  
Sun Leaves ◽  
Different Sources ◽  
Effect Of Light

Photosynthetic rates of detached, mature tea leaves from four different sources were determined in excess CO2 and light of 4, 10, 16 and 32 klux intensities from a tungsten-filament lamp. Temperature was maintained at 25°C. The assimilation rates were significantly different for the four sources both in weak and in strong light. Neither thickness of the leaf lamina nor chlorophyll concentration could explain the cause of this difference.The effect of shade adaptation on the subsequent rate of assimilation was examined in one of the four sources of leaf. Shade-adapted leaves had significantly higher rates of photosynthesis at the weakest light intensity of 4 klux and lower rates in 16 and 32 klux intensities than the corresponding sun leaves.

scholarly journals Caracterización ficológica en manantiales de la cuenca baja del sistema hidrológico del Pánuco, México

2017 ◽  
pp. 21 ◽  
Author(s):  
Javier Carmona-Jiménez ◽  
Gustavo Montejano-Zurita
Keyword(s):  
Environmental Factors ◽  
Light Intensity ◽  
Current Velocity ◽  
Growth Forms ◽  
Factors Affecting ◽  
Similarities And Differences ◽  
The Relationship

The results of a phycofloristic study on three springs in the Huasteca Potosina region are presented; 67 species are reported. Floristic similarities and differences among the springsare analized, as well as the relationship between species and environmental factors. Microhabitas were defined in the springs as well as the principal algal asociations that characterize them. Light intensity and current velocity are the most important factors affecting the predominant growth forms present in this type of habitat.

scholarly journals Describing the Relationship between a Weather Event and Climate Change: A New Statistical Approach

2020 ◽  
Vol 33 (15) ◽  
pp. 6297-6314 ◽  
Author(s):  
Aurélien Ribes ◽  
Soulivanh Thao ◽  
Julien Cattiaux
Keyword(s):  
Climate Change ◽  
Sources Of Information ◽  
Single Model ◽  
Coupled Models ◽  
Weather Event ◽  
Event Attribution ◽  
Transient Simulations ◽  
Induced Changes ◽  
The Relationship

AbstractDescribing the relationship between a weather event and climate change—a science usually termed event attribution—involves quantifying the extent to which human influence has affected the frequency or the strength of an observed event. In this study we show how event attribution can be implemented through the application of nonstationary statistics to transient simulations, typically covering the 1850–2100 period. The use of existing CMIP-style simulations has many advantages, including their availability for a large range of coupled models and the fact that they are not conditional to a given oceanic state. We develop a technique for providing a multimodel synthesis, consistent with the uncertainty analysis of long-term changes. Last, we describe how model estimates can be combined with historical observations to provide a single diagnosis accounting for both sources of information. The potential of this new method is illustrated using the 2003 European heat wave and under a Gaussian assumption. Results suggest that (i) it is feasible to perform event attribution using transient simulations and nonstationary statistics, even for a single model; (ii) the use of multimodel synthesis in event attribution is highly desirable given the spread in single-model estimates; and (iii) merging models and observations substantially reduces uncertainties in human-induced changes. Investigating transient simulations also enables us to derive insightful diagnostics of how the targeted event will be affected by climate change in the future.

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