scholarly journals The morning burst: Shifting daily patterns of ATP production in Drosophila and temporal windows for their improvement in ageing

2021 ◽  
Author(s):  
Harpreet Shinhmar ◽  
Jaimie Hoh Kam ◽  
John Mitrofanis ◽  
Chris Hogg ◽  
Glen Jeffery
Keyword(s):  
Mitochondrial Membrane ◽  
Cell Function ◽  
Complex Dynamic ◽  
Spare Capacity ◽  
Atp Production ◽  
Long Wavelength ◽  
Time Points ◽  
Dynamic Relationship ◽  
Temporal Windows ◽  
Wavelength Light

AbstractMitochondria produce energy for cell function via adenosine triphosphate (ATP) and are regulated by a molecular 24h clock. Here we use Drosophila melanogaster to reveal shifts in whole animal ATP production over 24h, showing a marked peak in the morning that declines around midday and remains low from then through to the following morning. Mitochondrial membrane potential and ATP production has been shown previously to improve after long wavelength exposure, but apparently not at all times. Hence, to explore this further we exposed flies to 670nm at different times. Exposures between 08.00 and 11.00 resulted in a significant increase in ATP, while exposures at other times had no effect. Within the morning window, not all times were equally effective, however, 670nm exposure mid-morning when ATP production was maximal did not increase ATP, possibly because mitochondria lacked spare capacity at this time. Hence, in the morning there is a complex dynamic relationship between long wavelength light and mitochondria. Mitochondrial function and the influence of long wavelengths are conserved across species from fly to human, and determining the time points for light administration to improve function in ageing and disease is of key importance. Our data progress this search and reveal the outline of these times.

scholarly journals Demonstration of epitaxial growth of strain-relaxed GaN films on graphene/SiC substrates for long wavelength light-emitting diodes

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Ye Yu ◽  
Tao Wang ◽  
Xiufang Chen ◽  
Lidong Zhang ◽  
Yang Wang ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Light Emitting Diodes ◽  
Nitrogen Plasma ◽  
Biaxial Stress ◽  
Organic Chemical ◽  
Graphene Surface ◽  
Light Emitting ◽  
Long Wavelength ◽  
Pre Treatment ◽  
Wavelength Light

AbstractStrain modulation is crucial for heteroepitaxy such as GaN on foreign substrates. Here, the epitaxy of strain-relaxed GaN films on graphene/SiC substrates by metal-organic chemical vapor deposition is demonstrated. Graphene was directly prepared on SiC substrates by thermal decomposition. Its pre-treatment with nitrogen-plasma can introduce C–N dangling bonds, which provides nucleation sites for subsequent epitaxial growth. The scanning transmission electron microscopy measurements confirm that part of graphene surface was etched by nitrogen-plasma. We study the growth behavior on different areas of graphene surface after pre-treatment, and propose a growth model to explain the epitaxial growth mechanism of GaN films on graphene. Significantly, graphene is found to be effective to reduce the biaxial stress in GaN films and the strain relaxation improves indium-atom incorporation in InGaN/GaN multiple quantum wells (MQWs) active region, which results in the obvious red-shift of light-emitting wavelength of InGaN/GaN MQWs. This work opens up a new way for the fabrication of GaN-based long wavelength light-emitting diodes.

scholarly journals A day in the life of mitochondria reveals shifting workloads

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tobias W. Weinrich ◽  
Jaimie Hoh Kam ◽  
Bill T. Ferrara ◽  
Elinor P. Thompson ◽  
John Mitrofanis ◽  
...  
Keyword(s):  
Complex I ◽  
Energy Capacity ◽  
Complex Activity ◽  
Spare Capacity ◽  
Atp Production ◽  
Cellular Energy ◽  
Changing Patterns ◽  
Differential Transcription ◽  
Stimulation Of

Abstract Mitochondria provide energy for cellular function. We examine daily changing patterns of mitochondrial function and metabolism in Drosophila in vivo in terms of their complex (I-IV) activity, ATP production, glycolysis, and whole fly respiration in the morning, afternoon and night. Complex activity and respiration showed significant and unexpected variation, peaking in the afternoon. However, ATP levels by contrast are >40% greater in the morning and lowest at night when glycolysis peaks. Complex activity modulation was at the protein level with no evidence for differential transcription over the day. Timing differences between increased ATP production and peaks of complex activity may result from more efficient ATP production early in the day leaving complex activity with spare capacity. Optical stimulation of mitochondria is only possible in the mornings when there is such spare capacity. These results provide first evidence of shifts in cellular energy capacity at the organism level. Understanding their translation may be significant to the chosen timing of energy demanding interventions to improve function and health.

Metformin Collaborates With PINK1/Mfn2 Overexpression Prevented Isoproterenol-Induced Cardiomyocyte Injury By Improving Mitochondrial Function

2021 ◽  
Author(s):  
Zhuang Ma ◽  
Zuheng Liu ◽  
Yuting Xue ◽  
Hao Zhang ◽  
Wenjun Xiong ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Energy Metabolism ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Biogenesis ◽  
Mitochondrial Membrane ◽  
Mitochondrial Morphology ◽  
Dependent Manner ◽  
Combination Strategy ◽  
Mitochondrial Energy Metabolism ◽  
Atp Production

Abstract Background: Both mitochondrial quality control and energy metabolism are critical in maintaining the physiological function of cardiomyocytes. Previous studies indicated that PGC-1α is a transcription co-activator in promoting mitochondrial energy metabolism which would be beneficial for cardiomyocytes. However, PGC-1α overexpression in heart tissues could also result in the development of cardiomyopathy. This discrepancy in vivo and in vitro might be due to neglecting the elimination of damaged mitochondrial. Thus, an integration strategy of mitochondrial biogenesis and mitophagy might be beneficial.Methods: We studied the function of PINK1 in mitophagy in isoproterenol (Iso)-induced cardiomyocyte injury. Adenovirus was used to provoke an overexpression of the PINK1/Mfn2 protein. Mitochondrial morphology was examined via electron microscopy and confocal microscopy. Cardiomyocytes injury were measured by mitochondrial membrane potential (MMP), reactive oxygen species (ROS) and apoptosis. Metformin was used to increase mitochondrial biogenesis, the level of which was detected via immunoblotting. Additionally, mitochondrial respiratory function was measured by ATP production and oxygen consumption rate (OCR). Results: Cardiomyocytes treated with Iso had high levels of PINK1 and low levels of Mfn2 in a time-dependent manner. PINK1 overexpression promoted mitophagy, alleviated Iso-induced reduction in MMP, reduced ROS production and the apoptotic rate. In addition to increasing mitophagy, metformin could promote mitochondrial biogenensis and the overexpression of Mfn2 induce mitochondrial fusion. Moreover, metformin treatment and PINK1/Mfn2 overexpression reduced the mitochondrial dysfunction by inhibiting the generation of ROS, and leading to an increase in both ATP production and mitochondrial membrane potential in Iso-induced cardiomyocytes injury. Conclusion: Our findings indicate that a combination strategy may help ameliorate myocardial injury through mitophagy and mitochondrial biogenesis.

Light Trapping in Thin Film Silicon n-i-p Solar Cells - Gains and Losses

2008 ◽  
Vol 1101 ◽  
Author(s):  
Ruud E.I. Schropp ◽  
Hongbo Li ◽  
Jatin K. Rath ◽  
Ronald H. Franken
Keyword(s):  
Thin Film ◽  
Light Trapping ◽  
Structural Defects ◽  
Metallic Surface ◽  
Textured Surfaces ◽  
Long Wavelength ◽  
Thin Film Silicon ◽  
Internal Surfaces ◽  
Gains And Losses ◽  
Wavelength Light

AbstractThin film silicon solar cell technology frequently makes use of rough or textured surfaces in order to enhance light absorption within the thin absorber layers by scattering and total internal reflection (“light trapping”). The rough morphology of the optically functional internal surfaces both in superstrate and substrate cells however, not only has a beneficial effect on light scattering properties, but on the other hand may also have deleterious effects on the microscopic structure of the deposited layers, in particular if these layers are nanocrystalline. The narrow valleys in the surface morphology may lead to structural defects, such as cavities and pinholes. By adjusting the morphology, these defects can be avoided.However, even when structural defects in layers directly deposited on rough interfaces are avoided, the obtained optically defined maximum current density is still much lower than expected. For instance, in n-i-p structures the rough interface (the textured back reflector consisting of nanostructured Ag coated with ZnO) is located at the back of the cell, where only long wavelength light is present. The natively textured Ag film is sputtered at elevated temperature and optimized for diffusely reflecting this long wavelength light. From experiments we infer that the nanostructured metallic surface also gives rise to plasmon absorption in the red and near IR, and that this leads to a parasitic absorption, i.e. at least part of the absorbed energy is not re-emitted to the active layers.

scholarly journals The hyperopic effect of narrow-band long-wavelength light in tree shrews increases non-linearly with duration

2018 ◽  
Vol 146-147 ◽  
pp. 9-17 ◽  
Author(s):  
Alexander H. Ward ◽  
Thomas T. Norton ◽  
Carrie E. Huisingh ◽  
Timothy J. Gawne
Keyword(s):  
Narrow Band ◽  
Tree Shrews ◽  
Long Wavelength ◽  
Wavelength Light

Practical infra-red illumination and observation techniques for wildlife studies using ICI-962 perspex

2003 ◽  
Vol 25 (2) ◽  
pp. 201 ◽  
Author(s):  
C Marks ◽  
F Busana ◽  
F Gigliotti ◽  
M Lindeman
Keyword(s):  
Uv Light ◽  
Ultra Violet ◽  
Ir Radiation ◽  
Long Wavelength ◽  
Non Invasive ◽  
Radiation Sources ◽  
Infra Red ◽  
Invaluable Tool ◽  
Free Ranging ◽  
Wavelength Light

MAMMALS do not normally visually perceive infrared (IR) or ultra-violet (UV) light that exists on either side of the visual spectrum from 390 to 760 nanometers (nm) (Wolken 1975). There is no evidence to suggest that nocturnal mammals have become more sensitive to long wavelength light as an adaptive response (Lythgoe 1979), although some reptiles can sense longer wavelength, thermal IR radiation (Barrett et al. 1970). Because it is not perceived, and is unlikely to affect animal behaviour, IR observation can be an invaluable tool for wildlife researchers. This paper describes the construction and use of simple IR radiation sources that can be used for non-invasive behavioural observations of captive and free-ranging mammals.

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