Dynamics of the processes leading to the acquisition of sensitivity to very low fluence of photons inDatura feroxseeds

2013 ◽  
Vol 23 (4) ◽  
pp. 233-239
Author(s):  
Gabriela Alejandra Auge ◽  
Lucila de Miguel
Keyword(s):  
Physiological State ◽  
Red Light ◽  
Light Sensitivity ◽  
Growth Potential ◽  
Soil Tillage ◽  
Phytochrome A ◽  
Light Stimulation ◽  
Endosperm Weakening ◽  
Signalling Network ◽  
Stimulation Of

AbstractSoil tillage operations stimulate germination of buried seeds in cultivated lands, allowing them to perceive light as a germination-promoting factor. The time of burial and the effect of changing environmental factors affect the physiological state of the seeds, which may lead to an extreme light-sensitivity and very low fluence response (VLFR) through phytochrome A. This paper describes the influence of the progressive process of dormancy breakage, which is accompanied by the acquisition of extreme light-sensitivity, on processes associated with endosperm weakening and embryo growth potential in the VLFR-mediated promotion ofDatura feroxseed germination. Our results show that endosperm weakening is mainly limited by β-mannosidase enzyme activity after far-red light stimulation, which is highly dependent on the dormancy level of the seeds. In addition, stimulation of the embryo growth potential by far-red irradiation did not require an extreme light-sensitivity to very low fluence of photons to reach its maximum response, and it was not completely correlated with expansin gene expression in the embryo. Our work indicates that responses of endosperm weakening and embryo growth potential to far-red irradiation, dependent on dormancy level, have different requirements for stimulation by the signalling network initiated by phytochrome A during the course of the very low fluence response inDatura feroxseeds.

scholarly journals Red LED Light Acts on the Mitochondrial Electron Chain of Donkey Sperm and Its Effects Depend on the Time of Exposure to Light

2020 ◽  
Vol 8 ◽  
Author(s):  
Jaime Catalán ◽  
Marion Papas ◽  
Lina Trujillo-Rojas ◽  
Olga Blanco-Prieto ◽  
Sebastián Bonilla-Correal ◽  
...  
Keyword(s):  
Red Light ◽  
Specific Inhibitor ◽  
Motile Sperm ◽  
Light Stimulation ◽  
Led Light ◽  
Mitochondrial Atp Synthase ◽  
Red Led ◽  
Oligomycin A ◽  
Rate Of Oxygen Consumption ◽  
Stimulation Of

This work aimed to investigate how stimulation of donkey sperm with red LED light affects mitochondrial function. For this purpose, freshly diluted donkey semen was stimulated with red light for 1, 5, and 10 min, in the presence or absence of oligomycin A (Omy A), a specific inhibitor of mitochondrial ATP synthase, or FCCP, a specific disruptor of mitochondrial electron chain. The results obtained in the present study indicated that the effects of red LED light on fresh donkey sperm function are related to changes in mitochondria function. In effect, irradiation of donkey sperm resulted in an increase in mitochondrial membrane potential (MMP), the activity of cytochrome C oxidase and the rate of oxygen consumption. In addition, in the absence of oligomycin A and FCCP, light-stimulation augmented the average path velocity (VAP) and modified the structure of motile sperm subpopulations, increasing the fastest and most linear subpopulation. In contrast, the presence of either Omy A or FCCP abolished the aforementioned effects. Interestingly, our results also showed that the effects of red light depend on the exposure time applied, as indicated by the observed differences between irradiation protocols. In conclusion, our results suggest that exposing fresh donkey sperm to red light modulates the function of their mitochondria through affecting the activity of the electron chain. However, the extent of this effect depends on the irradiation pattern and does not exclude the existence of other mechanisms, such as those related to thermotaxis.

scholarly journals Light Stimulation of Active Transport in Hydrodictyon africanum

1967 ◽  
Vol 50 (6) ◽  
pp. 1627-1640 ◽  
Author(s):  
J. A. Raven
Keyword(s):  
Active Transport ◽  
Photosystem 2 ◽  
Red Light ◽  
Gas Mixtures ◽  
Light Stimulation ◽  
Cyclic Photophosphorylation ◽  
Na Efflux ◽  
Stimulation Of

The mechanism of light stimulation of active K and Cl influx and active Na efflux, in Hydrodictyon africanum has been investigated using different wavelengths of red light and different gas mixtures, and the inhibitors DCMU and CCCP. The active Cl influx requires photosystem 2, since its relative quantal efficiency falls with increasing wavelength of red light, and it is as sensitive to the inhibitor DCMU as is photosynthesis; it is relatively insensitive to the uncoupler CCCP. The active K influx and active Na efflux are inhibited by CCCP, but the relative quantal efficiency of these processes increases with increasing wavelength of red light, and they are relatively insensitive to DCMU. These cation fluxes can be supported by cyclic photophosphorylation, whereas Cl influx needs photosystem 2 but probably not ATP.

Einfluss der Rotlichtstimulation auf die Fruchtbarkeit von Ebersperma

2019 ◽  
Vol 47 (05) ◽  
pp. 328-329
Keyword(s):  
Artificial Insemination ◽  
Red Light ◽  
Light Stimulation ◽  
Boar Semen ◽  
Stimulation Of

Blanco Prieto O, Catalán J, Lleonart M et al. Red-light stimulation of boar semen prior to artificial insemination improves field fertility in farms: A worldwide survey. Reprod Dom Anim 2019; 54: 1145–1148 In der weltweiten Schweinezucht ist die künstliche Besamung (KB) mit flüssigkonserviertem Sperma die vorherrschende Methode in der Reproduktion. Aus diesem Grund spielt die Optimierung der KB und damit der Reproduktionsleistung eine wichtige wirtschaftliche Rolle. Mehreren Studien zufolge kann die Rotlichtstimulation mit verschiedenen Lichtquellen die Beweglichkeit und In-vitro-Fertilisationsfähigkeit der Spermien von Säugetieren verbessern. Bei Ebersperma ließ sich zeigen, dass eine LED-basierte Rotlichtstimulation die Befruchtungsfähigkeit in vivo erhöht. Andere Studien ergaben variable Effekte der Rotlichtstimulation auf die in vitro untersuchten Spermienqualitätsparameter. Ziel dieser Studie war daher zu überprüfen, ob die Rotlichtstimulation mit dem Gerät MaXipig® unmittelbar vor der KB die mit dem behandelten Ebersperma erzielte Reproduktionsleistung steigert.

Red‐light stimulation of boar semen prior to artificial insemination improves field fertility in farms: A worldwide survey

2019 ◽  
Vol 54 (8) ◽  
pp. 1145-1148 ◽  
Author(s):  
Olga Blanco Prieto ◽  
Jaime Catalán ◽  
Marcel Lleonart ◽  
Sergi Bonet ◽  
Marc Yeste ◽  
...  
Keyword(s):  
Artificial Insemination ◽  
Red Light ◽  
Light Stimulation ◽  
Boar Semen ◽  
Stimulation Of

Far-Red Light Blocks Greening of Arabidopsis Seedlings via a Phytochrome A: Mediated Change in Plastid Development

1996 ◽  
Vol 8 (4) ◽  
pp. 601 ◽  
Author(s):  
Simon A. Barnes ◽  
Naoko K. Nishizawa ◽  
Ronaldo B. Quaggio ◽  
Garry C. Whitelam ◽  
Nam-Hai Chua
Keyword(s):  
Red Light ◽  
Phytochrome A ◽  
Plastid Development

Market exits during the pandemic

2021 ◽  
pp. 113-133
Author(s):  
E. V. Bessonova ◽  
S. M. Myakisheva ◽  
A. N. Tsvetkova
Keyword(s):  
Growth Potential ◽  
Efficiency Enhancement ◽  
High Productivity ◽  
Young Firms ◽  
Lower Productivity ◽  
Fast Development ◽  
Negative Effect ◽  
Positive Effect ◽  
Substantial Rise ◽  
Stimulation Of

The new coronavirus pandemic has triggered an economic crisis different from other crises in the acuteness and non-uniformity of its impact on various sectors of the economy. This paper analyzes how the dynamics of firms entering and exiting the market have changed in this environment and which groups of firms have shown to be the most vulnerable to the negative effect of the crisis. Our analysis shows that the number of newly registered firms dwindled sharply in the period of the toughest restrictions imposed to curtail the infection spread in April — May 2020. The recovery which followed in the subsequent months has failed to compensate for the spring’s slump, which may suggest a “scarring impact” of the crisis. July and October 2020 saw a substantial rise in companies’ exits from the market. The crisis has hurt not only the hardest hit industries but also other areas of economic activity. Liquidations rose most extensively among young firms aged less than three years. Relatively higher productivity firms exited less often than lower productivity companies. This may suggest a “cleansing effect” of the crisis. But with the redundant labor being unable to move to more productive firms, the positive effect of the crisis may be brought to naught. Therefore, for the consequences of the crisis to be remedied, incentives should be provided to new firms’ entries and support for efficient companies, especially for young firms showing growth potential. Stimulation of growth in the number of high-productivity firms should go hand in hand with the creation of conditions for new entities’ fast development, expansion, and efficiency enhancement.

scholarly journals Reversible Actuation Ability upon Light Stimulation of the Smart Systems with Controllably Grafted Graphene Oxide with Poly (Glycidyl Methacrylate) and PDMS Elastomer: Effect of Compatibility and Graphene Oxide Reduction on the Photo-Actuation Performance

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 832 ◽  
Author(s):  
Josef Osicka ◽  
Miroslav Mrlik ◽  
Marketa Ilcikova ◽  
Barbora Hanulikova ◽  
Pavel Urbanek ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Glycidyl Methacrylate ◽  
Mechanical Response ◽  
Dynamic Mechanical Properties ◽  
Light Stimulation ◽  
Smart Systems ◽  
Elastomeric Matrix ◽  
Chain Mobility ◽  
Angle Measurements ◽  
Stimulation Of

This study is focused on the controllable reduction of the graphene oxide (GO) during the surface-initiated atom transfer radical polymerization technique of glycidyl methacrylate (GMA). The successful modification was confirmed using TGA-FTIR analysis and TEM microscopy observation of the polymer shell. The simultaneous reduction of the GO particles was confirmed indirectly via TGA and directly via Raman spectroscopy and electrical conductivity investigations. Enhanced compatibility of the GO-PGMA particles with a polydimethylsiloxane (PDMS) elastomeric matrix was proven using contact angle measurements. Prepared composites were further investigated through the dielectric spectroscopy to provide information about the polymer chain mobility through the activation energy. Dynamic mechanical properties investigation showed an excellent mechanical response on the dynamic stimulation at a broad temperature range. Thermal conductivity evaluation also confirmed the further photo-actuation capability properties at light stimulation of various intensities and proved that composite material consisting of GO-PGMA particles provide systems with a significantly enhanced capability in comparison with neat GO as well as neat PDMS matrix.

scholarly journals Modulating the Blood-Brain Barrier by Light Stimulation of Molecular-Targeted Nanoparticles

2020 ◽  
Author(s):  
Xiaoqing Li ◽  
Vamsidhara Vemireddy ◽  
Qi Cai ◽  
Hejian Xiong ◽  
Peiyuan Kang ◽  
...  
Keyword(s):  
Tight Junction ◽  
Tight Junctions ◽  
Blood Brain Barrier ◽  
Therapeutic Interventions ◽  
Brain Barrier ◽  
Light Stimulation ◽  
Targeted Nanoparticles ◽  
Blood Brain ◽  
The Brain ◽  
Stimulation Of

AbstractThe blood-brain barrier (BBB) tightly regulates the entry of molecules into the brain by tight junctions that seals the paracellular space and receptor-mediated transcytosis. It remains elusive to selectively modulate these mechanisms and to overcome BBB without significant neurotoxicity. Here we report that light stimulation of tight junction-targeted plasmonic nanoparticles selectively opens up the paracellular route to allow diffusion through the compromised tight junction and into the brain parenchyma. The BBB modulation does not impair vascular dynamics and associated neurovascular coupling, or cause significant neural injury. It further allows antibody and adeno-associated virus delivery into local brain regions. This novel method offers the first evidence of selectively modulating BBB tight junctions and opens new avenues for therapeutic interventions in the central nervous system.One Sentence SummaryGentle stimulation of molecular-targeted nanoparticles selectively opens up the paracellular pathway and allows macromolecules and gene therapy vectors into the brain.

scholarly journals Stimulus-secretion coupling in the neurohypophysis of the jerboa Jaculus orientalis.

1994 ◽  
Vol 195 (1) ◽  
pp. 19-34
Author(s):  
A Raji ◽  
J J Nordmann
Keyword(s):  
Time Course ◽  
Physiological State ◽  
Nerve Endings ◽  
Neurosecretory System ◽  
Channel Blockers ◽  
Vasopressin Release ◽  
Oxytocin Release ◽  
Stimulus Secretion Coupling ◽  
Stimulation Of

1. In many mammals, severe dehydration is known to cause exhaustion of the vasopressin content of the neural lobe. Here, we have examined the physiological state of the neurohypophysis of the jerboa Jaculus orientalis, a rodent inhabitant of a semi-desert climate. 2. Isolated neurohypophyses and neurosecretory nerve endings were perfused in vitro and vasopressin and oxytocin release were determined by radioimmunoassay. 3. Electrical stimulation of the neurohypophysis with bursts of pulses mimicking the activity of hypersecreting neuroendocrine neurones induced similar increases of secretion in both control animals and animals dehydrated for up to 2 months. Neurohormone release was greatly potentiated when the bursts of pulses were separated by silent intervals. 4. Prolonged stimulation of neurohypophyses from both control and dehydrated animals induced a sustained increase of vasopressin release; in contrast, oxytocin release under similar conditions showed a biphasic secretory pattern consisting of a transient increase that subsequently decreased to a steady level whose amplitude was similar to that for vasopressin. 5. K(+)-induced secretion was largely inhibited by the Ca2+ channel blockers nicardipine and omega-conotoxin, suggesting that in this neurosecretory system both L- and N-type calcium channels play a major role in stimulus-secretion coupling. Depolarization of isolated nerve endings using a fast-flow perifusion system showed that there was no difference in the amplitude and the time course of the secretory response in dehydrated and hydrated animals. 6. The results demonstrate that, despite the climatic conditions in which the jerboas live, their neural lobes retain the capacity to release, upon depolarization of the plasma membrane of the nerve endings, large amounts of neurohormone. It is concluded that the neurohypophyseal peptidergic release system in the dehydrated jerboa functions adequately even under extreme environmental stress.

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