High light stress reduces dinoflagellate predation on phytoplankton through both direct and indirect responses

2020 ◽  
Vol 84 ◽  
pp. 43-57
Author(s):  
SL Strom ◽  
O Barberi ◽  
C Mazur ◽  
K Bright ◽  
K Fredrickson
Keyword(s):  
Stress Responses ◽  
Physiological Condition ◽  
Light Exposure ◽  
Light Stress ◽  
High Light ◽  
Chemical Signaling ◽  
Predator Prey ◽  
Oxyrrhis Marina ◽  
Acquisition Strategies ◽  
Protist Species

This study investigated the influence of light stress on predator-prey interactions between phytoplankton and heterotrophic dinoflagellates. Among the studied phytoplankton species (dinoflagellates, cryptophytes, and prymnesiophytes), the coccolithophore Emiliania huxleyi was particularly sensitive to light stress, as evidenced by photosynthetic efficiency (Fv/Fm) responses and flow cytometry measures of physiological condition. In addition, E. huxleyi was the only studied prey species that experienced reduced dinoflagellate predation when light stressed: predation on stressed E. huxleyi decreased by an average of 49% relative to controls (range: 23-80%). These light stress and predation responses applied to both calcifying and non-calcifying E. huxleyi strains. High light exposure led to elevated production of dissolved dimethylsulfoniopropionate (DMSP) in one strain of E. huxleyi, a signal that was associated with decreased predation. Direct effects of light stress on the 2 dinoflagellate predators also differed. Predation by Amphidinium longum was strongly decreased by UV exposure, while predation by Oxyrrhis marina was largely unaffected. Our findings highlight the deep diversity that is characteristic of the planktonic protists, and point to chemical signaling as a means by which the effects of light stress can propagate into predation interactions. When defining the ecological niche of planktonic protist species, stress responses should be considered along with the resource acquisition strategies that support growth.

scholarly journals Glutathione and zeaxanthin formation during high light stress in foliose lichens

2008 ◽  
Vol 53 (No. 8) ◽  
pp. 340-344 ◽  
Author(s):  
J. Štepigová ◽  
H. Vráblíková ◽  
J. Lang ◽  
K. Večeřová ◽  
M. Barták
Keyword(s):  
Xanthophyll Cycle ◽  
Light Exposure ◽  
Light Stress ◽  
High Light ◽  
Short Term ◽  
Xanthophyll Cycle Pigments ◽  
High Light Stress ◽  
Fluorescence Label ◽  
Thiol Binding ◽  
Pure Acetone

In the presented study, we describe techniques for glutathione and pigment determination in lichens used in our laboratory. Glutathione and xanthophyll cycle pigments, especially zeaxanthin, are important antioxidants protecting plants against various stresses. In our laboratory, the high light stress in lichens has been intensively studied for several years. We extract glutathione in HCl and determine it by thiol-binding fluorescence label monobromobimane. For pigment determination, homogenized lichen thalli are extracted with pure acetone. According to our results, the total amount of glutathione decreases after a short-term high light exposure, while the amount of zeaxanthin increases.

Photobiology of the symbiotic acoel flatworm Symsagittifera roscoffensis: algal symbiont photoacclimation and host photobehaviour

2010 ◽  
Vol 91 (1) ◽  
pp. 163-171 ◽  
Author(s):  
João Serôdio ◽  
Raquel Silva ◽  
João Ezequiel ◽  
Ricardo Calado
Keyword(s):  
Photosynthetic Activity ◽  
Light Exposure ◽  
Light Stress ◽  
Photosynthetic Apparatus ◽  
Light Response ◽  
High Light ◽  
Symbiotic Association ◽  
Light Levels ◽  
Light Gradient ◽  
Custom Made

The symbiotic association between the acoel flatworm Symsagittifera roscoffensis and the prasinophyte microalgae Tetraselmis convolutae was studied regarding its photophysiology and photobehaviour. The photoacclimation status and the photophysiological responses to high light of the algal endosymbiont were studied non-destructively on individual S. roscoffensis using pulse amplitude modulated fluorometry. Specimens collected in an intertidal sandy shore were characterized regarding the maximum quantum yield of photosystem II (PSII), Fv/Fm, and the light response of photosynthetic activity, by constructing rapid light-response curves of the relative electron transport rate of PSII, rETR. The studied population could be considered as high light-acclimated when compared with other intertidal photosynthetic organisms (e.g. macroalgae), with the light-saturation parameter Ek averaging 250 μmol m−2 s−1. Light stress experiments showed S. roscoffensis to be able to withstand the exposure to high light without displaying signs of photoinhibition, suggesting the operation of efficient physiological photoprotective processes. The photobehaviour of S. roscoffensis was studied by characterizing the distribution of the flatworms under a light gradient, using a custom-made photoaccumulation chamber. The results showed a photoaccumulation pattern evidencing a clear avoidance of extreme low or high light levels, and with maximum photoaccumulation values being found for a range of irradiances (150–400 μmol m−2 s−1) that generally coincided with the optima for photosynthetic activity. This matching between the optimum light levels for photosynthetic activity and photoaccumulation suggested that S. roscoffensis may use vertical migration as a form of behavioural photoprotection. This behavioural response may be used to rapidly and flexibly control light exposure, avoiding photodamage to the endosymbiont photosynthetic apparatus by direct exposure to sunlight.

Diverse roles for chloroplast stromal and thylakoid-bound ascorbate peroxidases in plant stress responses

2008 ◽  
Vol 412 (2) ◽  
pp. 275-285 ◽  
Author(s):  
Saijaliisa Kangasjärvi ◽  
Anna Lepistö ◽  
Kati Hännikäinen ◽  
Mirva Piippo ◽  
Eeva-Maria Luomala ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stress Responses ◽  
Double Mutant ◽  
Light Stress ◽  
Plant Stress ◽  
Optimal Growth ◽  
Sudden Onset ◽  
High Light ◽  
Mature Leaves ◽  
Ascorbate Peroxidases

Photosynthetic light reactions comprise a significant source of hydrogen peroxide (H2O2) in illuminated leaves. APXs (ascorbate peroxidases) reduce H2O2 to water and play an important role in the antioxidant system of plants. In the present study we addressed the significance of chloroplast APXs in stress tolerance and signalling in Arabidopsis thaliana. To this end, T-DNA (transfer DNA) insertion mutants tapx, sapx and tapx sapx, lacking the tAPX (thylakoid-bound APX), sAPX (stromal APX) or both respectively, were characterized. Photo-oxidative stress during germination led to bleaching of chloroplasts in sapx single-mutant and particularly in the tapx sapx double-mutant plants, whereas the greening process of wild-type and tapx plants was only partially impaired. Mature leaves of tapx sapx double mutants were also susceptible to short-term photo-oxidative stress induced by high light or methyl viologen treatments. After a 2-week acclimation period under high light or under low temperature, none of the mutants exhibited enhanced stress symptoms. Immunoblot analysis revealed that high-light-stress-acclimated tapx sapx double mutants compensated for the absence of tAPX and sAPX by increasing the level of 2-cysteine peroxiredoxin. Furthermore, the absence of tAPX and sAPX induced alterations in the transcriptomic profile of tapx sapx double-mutant plants already under quite optimal growth conditions. We conclude that sAPX is particularly important for photoprotection during the early greening process. In mature leaves, tAPX and sAPX are functionally redundant, and crucial upon sudden onset of oxidative stress. Moreover, chloroplast APXs contribute to chloroplast retrograde signalling pathways upon slight fluctuations in the accumulation of H2O2 in chloroplasts.

A mutation in the purine biosynthetic enzyme ATASE2 impacts high light signalling and acclimation responses in green and chlorotic sectors of Arabidopsis leaves

2011 ◽  
Vol 38 (5) ◽  
pp. 401 ◽  
Author(s):  
Nick S. Woo ◽  
Matthew J. Gordon ◽  
Stephen R. Graham ◽  
Jan Bart Rossel ◽  
Murray R. Badger ◽  
...  
Keyword(s):  
Stress Responses ◽  
Light Stress ◽  
High Light ◽  
Purine Biosynthesis ◽  
Dependent Manner ◽  
Phosphoribosyl Pyrophosphate ◽  
Partial Shading ◽  
High Light Stress ◽  
Genes Encoding ◽  
Photosynthesis Genes

In this report, we investigate the altered APX2 expression 13 (alx13) mutation of Arabidopsis thaliana, a mutation in glutamine phosphoribosyl pyrophosphate amidotransferase 2 (ATASE2), the primary isoform of the enzyme mediating the first committed step of purine biosynthesis. Light-dependent leaf variegation was exhibited by alx13 plants, with partial shading of alx13 rosettes revealing that the development of chlorosis in emerging leaves is influenced by the growth irradiance of established leaves. Chlorotic sectors arose from emerging green alx13 leaves during a phase of rapid cell division and expansion, which shows that each new cell’s fate is independent of its progenitor. In conjunction with the variegated phenotype, alx13 plants showed altered high light stress responses, including changed expression of genes encoding proteins with antioxidative functions, impaired anthocyanin production and over-accumulation of reactive oxygen species. These characteristics were observed in both photosynthetically-normal green tissues and chlorotic tissues. Chlorotic tissues of alx13 leaves accumulated mRNAs of nuclear-encoded photosynthesis genes that are repressed in other variegated mutants of Arabidopsis. Thus, defective purine biosynthesis impairs chloroplast biogenesis in a light-dependent manner and alters the induction of high light stress pathways and nuclear-encoded photosynthesis genes.

scholarly journals Stress Responses of Shade-Treated Tea Leaves to High Light Exposure after Removal of Shading

Plants ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 302 ◽  
Author(s):  
Satoshi Sano ◽  
Tetsuyuki Takemoto ◽  
Akira Ogihara ◽  
Kengo Suzuki ◽  
Takehiro Masumura ◽  
...  
Keyword(s):  
Stress Responses ◽  
Light Exposure ◽  
Culture Method ◽  
High Light ◽  
Rapid Decline ◽  
Chl A ◽  
Oxidative Damages ◽  
Young Leaves ◽  
Antioxidant Defense Systems ◽  
Tea Plants

High-quality green tea is produced from buds and young leaves grown by the covering-culture method, which employs shading treatment for tea plants (Camellia sinensis L.). Shading treatment improves the quality of tea, but shaded tea plants undergo sudden exposures to high light (HL) at the end of the treatment by shade removal. In this study, the stress response of shaded tea plants to HL illumination was examined in field condition. Chl a/b ratio was lower in shaded plants than nonshaded control, but it increased due to exposure to HL after 14 days. Rapid decline in Fv/Fm values and increases in carbonylated protein level were induced by HL illumination in the shaded leaves on the first day, and they recovered thereafter between a period of one and two weeks. These results revealed that shaded tea plants temporarily suffered from oxidative damages caused by HL exposure, but they could also recover from these damages in 2 weeks. The activities of antioxidant enzymes, total ascorbate level, and ascorbate/dehydroascorbate ratio were decreased and increased in response to low light and HL conditions, respectively, suggesting that the upregulation of antioxidant defense systems plays a role in the protection of the shaded tea plants from HL stress.

scholarly journals PENGARUH APLIKASI CAHAYA TERHADAP SPERMATOZOA MENCIT JANTAN (MUS MUSCULUS L)

2013 ◽  
Vol 1 (1) ◽  
Author(s):  
Junita Iriandini ◽  
Lydia Tendean ◽  
Benny Wantouw
Keyword(s):  
Psychological Stress ◽  
Mus Musculus ◽  
Stress Responses ◽  
Light Exposure ◽  
Light Stress ◽  
Experimental Studies ◽  
Endocrine System ◽  
Randomized Design ◽  
Completely Randomized Design

Abstract: Light as a form of physical and psychological stress responses activated central and peripheral endocrine system in general interfere with the process of spermatogenesis especially the quantity and quality of the sperm of mice consisted of concentration, morphology and motility. The purpose of this study was to determine the effect of the application of the quality of light as well as the mechanism of spermatozoa of mice. Experimental studies with a completely randomized design done in November and December 2012 using 27 mice as a sample for 30 days, each consist of nine mice as a control, nine mice were given 4 lamp light exposure (12 volts) and 9 others mice were given a presentation by 8 light exposure (24 volt). The results of this study found that the percentage of motility in the first nine treated mice by 25.22% abnormal and in the second treatment 35.66% were abnormal; concentration of spermatozoa in the first treatment were  7.43X105 abnormal and the second treatment 6.45X105 were abnormal; morphology of spermatozoa in the first treatment were 57.88% abnormal and 67.22% abnormal in the second treatment. The conclusion of this study found that the provision of light affect the quality of spermatozoa of mice include motility, morphology, concentration; and the higher the light application, the lower the quality spermatozoa in mice will be. Keywords: Light, Stress, Spermatozoa Quality of mice  Abstrak: Cahaya merupakan bentuk stress fisik dan psikologis mengaktifkan respon sentral dan perifer sistem endokrin yang secara umum mengganggu proses spermatogenesis khususnya terhadap kuantitas dan kualitas spermatozoa mencit terdiri dari konsentrasi, morfologi dan motilitas. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh aplikasi cahaya serta mekanismenya terhadap kualitas spermatozoa mencit. Penelitian eksperimental dengan rancangan acak lengkap di lakukan pada bulan November sampai Desember 2012 dengan menggunakan sampel sebanyak 27 ekor mencit selama 30 hari, masing-masing terdiri dari 9 ekor mencit sebagai kontrol, 9 mencit di beri pemaparan  cahaya sebanyak 4 lampu (12 volt) dan 9 mencit lainnya di beri pemaparan cahaya sebanyak 8 lampu (24 volt). Hasil dari peneltian ini didapatkan persentase motilitas pada 9 mencit perlakuan pertama  sebesar 25,22% abnormal dan pada perlakuan kedua 35,66% abnormal, konsentrasi spermatozoa pada perlakukan pertama 7,43x105 abnormal dan pada perlakuan kedua 6,45x105 abnormal, morfologi spermatozoa pada perlakukan pertama 57,88% abnormal dan pada perlakuan kedua 67,22% abnormal. Kesimpulan dari penelitian ini didapatkan bahwa pemberian cahaya lampu berpengaruh terhadap kualitas spermatozoa mencit dalam hal ini motilitas, morfologi, konsentrasi dan semakin aplikasi cahaya di naikkan maka kualitas spermatozoa mencit akan menurun. Kata kunci: Cahaya, Stres, Kualitas Spermatozoa mencit.

scholarly journals Structural changes of the thylakoid membrane network induced by high light stress in plant chloroplasts

2014 ◽  
Vol 369 (1640) ◽  
pp. 20130225 ◽  
Author(s):  
Helmut Kirchhoff
Keyword(s):  
Thylakoid Membrane ◽  
Structural Changes ◽  
Light Exposure ◽  
Light Stress ◽  
Photosynthetic Apparatus ◽  
Membrane System ◽  
Thylakoid Membranes ◽  
High Light ◽  
Irreversible Damage ◽  
Repair Cycle

Land plants live in a challenging environment dominated by unpredictable changes. A particular problem is fluctuation in sunlight intensity that can cause irreversible damage of components of the photosynthetic apparatus in thylakoid membranes under high light conditions. Although a battery of photoprotective mechanisms minimize damage, photoinhibition of the photosystem II (PSII) complex occurs. Plants have evolved a multi-step PSII repair cycle that allows efficient recovery from photooxidative PSII damage. An important feature of the repair cycle is its subcompartmentalization to stacked grana thylakoids and unstacked thylakoid regions. Thus, understanding the crosstalk between stacked and unstacked thylakoid membranes is essential to understand the PSII repair cycle. This review summarizes recent progress in our understanding of high-light-induced structural changes of the thylakoid membrane system and correlates these changes to the efficiency of the PSII repair cycle. The role of reversible protein phosphorylation for structural alterations is discussed. It turns out that dynamic changes in thylakoid membrane architecture triggered by high light exposure are central for efficient repair of PSII.

scholarly journals The Role of Chloroplast Gene Expression in Plant Responses to Environmental Stress

2020 ◽  
Vol 21 (17) ◽  
pp. 6082 ◽  
Author(s):  
Yi Zhang ◽  
Aihong Zhang ◽  
Xiuming Li ◽  
Congming Lu
Keyword(s):  
Gene Expression ◽  
Environmental Stress ◽  
Stress Responses ◽  
Light Stress ◽  
High Light ◽  
Plant Responses ◽  
Chloroplast Gene ◽  
Chloroplast Gene Expression ◽  
Endosymbiotic Origin

Chloroplasts are plant organelles that carry out photosynthesis, produce various metabolites, and sense changes in the external environment. Given their endosymbiotic origin, chloroplasts have retained independent genomes and gene-expression machinery. Most genes from the prokaryotic ancestors of chloroplasts were transferred into the nucleus over the course of evolution. However, the importance of chloroplast gene expression in environmental stress responses have recently become more apparent. Here, we discuss the emerging roles of the distinct chloroplast gene expression processes in plant responses to environmental stresses. For example, the transcription and translation of psbA play an important role in high-light stress responses. A better understanding of the connection between chloroplast gene expression and environmental stress responses is crucial for breeding stress-tolerant crops better able to cope with the rapidly changing environment.

scholarly journals PENGARUH APLIKASI CAHAYA TERHADAP SPERMATOZOA MENCIT JANTAN (MUS MUSCULUS L)

2013 ◽  
Vol 1 (1) ◽  
Author(s):  
Junita Iriandini ◽  
Lydia Tendean ◽  
Benny Wantouw
Keyword(s):  
Psychological Stress ◽  
Mus Musculus ◽  
Stress Responses ◽  
Light Exposure ◽  
Light Stress ◽  
Experimental Studies ◽  
Endocrine System ◽  
Randomized Design ◽  
Completely Randomized Design

Abstrak: Cahaya merupakan bentuk stress fisik dan psikologis mengaktifkan respon sentral dan perifer sistem endokrin yang secara umum mengganggu proses spermatogenesis khususnya terhadap kuantitas dan kualitas spermatozoa mencit terdiri dari konsentrasi, morfologi dan motilitas. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh aplikasi cahaya serta mekanismenya terhadap kualitas spermatozoa mencit. Penelitian eksperimental dengan rancangan acak lengkap di lakukan pada bulan November sampai Desember 2012 dengan menggunakan sampel sebanyak 27 ekor mencit selama 30 hari, masing-masing terdiri dari 9 ekor mencit sebagai kontrol, 9 mencit di beri pemaparan  cahaya sebanyak 4 lampu (12 volt) dan 9 mencit lainnya di beri pemaparan cahaya sebanyak 8 lampu (24 volt). Hasil dari peneltian ini didapatkan persentase motilitas pada 9 mencit perlakuan pertama  sebesar 25,22% abnormal dan pada perlakuan kedua 35,66% abnormal, konsentrasi spermatozoa pada perlakukan pertama 7,43x105 abnormal dan pada perlakuan kedua 6,45x105 abnormal, morfologi spermatozoa pada perlakukan pertama 57,88% abnormal dan pada perlakuan kedua 67,22% abnormal. Kesimpulan dari penelitian ini didapatkan bahwa pemberian cahaya lampu berpengaruh terhadap kualitas spermatozoa mencit dalam hal ini motilitas, morfologi, konsentrasi dan semakin aplikasi cahaya di naikkan maka kualitas spermatozoa mencit akan menurun. Kata kunci : Cahaya, Stres, Kualitas Spermatozoa mencit.  Abstract: Light as a form of physical and psychological stress responses activated central and peripheral endocrine system in general interfere with the process of spermatogenesis especially the quantity and quality of the sperm of mice consisted of concentration, morphology and motility. The purpose of this study was to determine the effect of the application of the quality of light as well as the mechanism of spermatozoa of mice. Experimental studies with a completely randomized design done in November and December 2012 using 27 mice as a sample for 30 days, each consist of nine mice as a control, nine mice were given 4 lamp light exposure (12 volts) and 9 others mice were given a presentation by 8 light exposure (24 volt). The results of this study found that the percentage of motility in the first nine treated mice by 25.22% abnormal and in the second treatment 35.66% were abnormal; concentration of spermatozoa in the first treatment were  7.43X105 abnormal and the second treatment 6.45X105 were abnormal; morphology of spermatozoa in the first treatment were 57.88% abnormal and 67.22% abnormal in the second treatment. The conclusion of this study found that the provision of light affect the quality of spermatozoa of mice include motility, morphology, concentration; and the higher the light application, the lower the quality spermatozoa in mice will be. Keywords: Light, Stress, Spermatozoa Quality of mice

Photosynthetic responses of Coffea arabica leaves to a short-term high light exposure in relation to N availability

1997 ◽  
Vol 101 (1) ◽  
pp. 229-239 ◽  
Author(s):  
Jose C. Ramalho ◽  
Thos L. Pons ◽  
Henri W. Groeneveld ◽  
M. Antonieta Nunes
Keyword(s):  
Coffea Arabica ◽  
Light Exposure ◽  
High Light ◽  
N Availability ◽  
Short Term ◽  
Photosynthetic Responses
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