scholarly journals A multifaceted analysis reveals two distinct phases of chloroplast biogenesis during de-etiolation in Arabidopsis

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Rosa Pipitone ◽  
Simona Eicke ◽  
Barbara Pfister ◽  
Gaetan Glauser ◽  
Denis Falconet ◽  
...  
Keyword(s):  
Thylakoid Membrane ◽  
Structural Data ◽  
Chloroplast Biogenesis ◽  
Time Resolved ◽  
Growth And Survival ◽  
Chloroplast Differentiation ◽  
Relative Contribution ◽  
Membrane Surfaces ◽  
Sequence Of Events ◽  
Block Face

Light triggers chloroplast differentiation whereby the etioplast transforms into a photosynthesizing chloroplast and the thylakoid rapidly emerges. However, the sequence of events during chloroplast differentiation remains poorly understood. Using Serial Block Face Scanning Electron Microscopy (SBF-SEM), we generated a series of chloroplast 3D reconstructions during differentiation, revealing chloroplast number and volume and the extent of envelope and thylakoid membrane surfaces. Furthermore, we used quantitative lipid and whole proteome data to complement the (ultra)structural data, providing a time-resolved, multi-dimensional description of chloroplast differentiation. This showed two distinct phases of chloroplast biogenesis: an initial photosynthesis-enabling ‘Structure Establishment Phase’ followed by a ‘Chloroplast Proliferation Phase’ during cell expansion. Moreover, these data detail thylakoid membrane expansion during de-etiolation at the seedling level and the relative contribution and differential regulation of proteins and lipids at each developmental stage. Altogether, we establish a roadmap for chloroplast differentiation, a critical process for plant photoautotrophic growth and survival.

scholarly journals Two distinct phases of chloroplast biogenesis during de-etiolation in Arabidopsis thaliana

2020 ◽  
Author(s):  
Rosa Pipitone ◽  
Simona Eicke ◽  
Barbara Pfister ◽  
Gaetan Glauser ◽  
Denis Falconet ◽  
...  
Keyword(s):  
Thylakoid Membrane ◽  
Structural Data ◽  
Chloroplast Biogenesis ◽  
Time Resolved ◽  
Growth And Survival ◽  
Chloroplast Differentiation ◽  
Relative Contribution ◽  
Membrane Surfaces ◽  
Sequence Of Events ◽  
Block Face

AbstractLight triggers chloroplast differentiation whereby the etioplast transforms into a photosynthesizing chloroplast and the thylakoid rapidly emerges. However, the sequence of events during chloroplast differentiation remains poorly understood. Using Serial Block Face Scanning Electron Microscopy (SBF-SEM), we generated a series of chloroplast 3D reconstructions during differentiation, revealing chloroplast number and volume and the extent of envelope and thylakoid membrane surfaces. Furthermore, we used quantitative lipid and whole proteome data to complement the (ultra)structural data, providing a time-resolved, multi-dimensional description of chloroplast differentiation. This showed two distinct phases of chloroplast biogenesis: an initial photosynthesis-enabling ‘Structure Establishment Phase’ followed by a ‘Chloroplast Proliferation Phase’ during cell expansion. Moreover, these data detail thylakoid membrane expansion during de-etiolation at the seedling level and the relative contribution and differential regulation of proteins and lipids at each developmental stage. Altogether, we establish a roadmap for chloroplast differentiation, a critical process for plant photoautotrophic growth and survival.

Time-resolved small angle scattering: kinetic and structural data from proteins in solution

2000 ◽  
Vol 33 (3) ◽  
pp. 548-551 ◽  
Author(s):  
M. Roessle ◽  
E. Manakova ◽  
I. Lauer ◽  
T. Nawroth ◽  
J. Holzinger ◽  
...  
Keyword(s):  
Small Angle ◽  
Structural Data ◽  
Small Angle Scattering ◽  
Time Resolved ◽  
Angle Scattering

Synthesis and Photophysical Properties of a Conformationally Flexible Mixed Porphyrin Star-Pentamer

2009 ◽  
Vol 62 (7) ◽  
pp. 692 ◽  
Author(s):  
Toby D. M. Bell ◽  
Sheshanath V. Bhosale ◽  
Kenneth P. Ghiggino ◽  
Steven J. Langford ◽  
Clint P. Woodward
Keyword(s):  
Energy Transfer ◽  
Photophysical Properties ◽  
Fluorescence Decay ◽  
High Yield ◽  
Free Base ◽  
Time Resolved ◽  
Zinc Porphyrin ◽  
Relative Contribution ◽  
Synthetic Strategy ◽  
Decay Times

The synthesis of a porphyrin star-pentamer bearing a free-base porphyrin core and four zinc(ii) metalloporphyrins, which are tethered by a conformationally flexible linker about the central porphyrin’s antipody, is described. The synthetic strategy is highlighted by the use of olefin cross metathesis to link the five chromophores together in a directed fashion in high yield. Photoexcitation into the Soret absorption band of the zinc porphyrin chromophores at 425 nm leads to a substantial enhancement of central free-base porphyrin fluorescence, indicating energy transfer from the photoexcited zinc porphyrin (outer periphery) to central free-base porphyrin. Time-resolved fluorescence decay profiles required three exponential decay components for satisfactory fitting. These are attributed to emission from the central free-base porphyrin and to two different rates of energy transfer from the zinc porphyrins to the free-base porphyrin. The faster of these decay components equates to an energy-transfer rate constant of 3.7 × 109 s–1 and an efficiency of 83%, whereas the other is essentially unquenched with respect to reported values for zinc porphyrin fluorescence decay times. The relative contribution of these two components to the initial fluorescence decay is ~3:2, similar to the 5:4 ratio of cis and trans geometric isomers present in the pentamer.

Isoelectric points of spinach thylakoid membrane surfaces as determined by cross partition

1979 ◽  
Vol 552 (2) ◽  
pp. 238-246 ◽  
Author(s):  
Hans-Erik Åkerlund ◽  
Bertil Andersson ◽  
Agneta Persson ◽  
Per-Åke Albertsson
Keyword(s):  
Thylakoid Membrane ◽  
Membrane Surfaces ◽  
Isoelectric Points ◽  
Spinach Thylakoid

Measurements of convective and radiative heating in wildland fires

2013 ◽  
Vol 22 (2) ◽  
pp. 157 ◽  
Author(s):  
David Frankman ◽  
Brent W. Webb ◽  
Bret W. Butler ◽  
Daniel Jimenez ◽  
Jason M. Forthofer ◽  
...  
Keyword(s):  
Fast Response ◽  
Radiative Heating ◽  
Radiative Energy ◽  
Convective Heating ◽  
Wildland Fires ◽  
Ambient Conditions ◽  
Heating Rates ◽  
Total Energy Release ◽  
Time Resolved ◽  
Relative Contribution

Time-resolved irradiance and convective heating and cooling of fast-response thermopile sensors were measured in 13 natural and prescribed wildland fires under a variety of fuel and ambient conditions. It was shown that a sensor exposed to the fire environment was subject to rapid fluctuations of convective transfer whereas irradiance measured by a windowed sensor was much less variable in time, increasing nearly monotonically with the approach of the flame front and largely declining with its passage. Irradiance beneath two crown fires peaked at 200 and 300 kW m–2, peak irradiance associated with fires in surface fuels reached 100 kW m–2 and the peak for three instances of burning in shrub fuels was 132 kW m–2. The fire radiative energy accounted for 79% of the variance in fuel consumption. Convective heating at the sensor surface varied from 15% to values exceeding the radiative flux. Detailed measurements of convective and radiative heating rates in wildland fires are presented. Results indicate that the relative contribution of each to total energy release is dependent on fuel and environment.

scholarly journals All-Atom Simulation of the HET-s Prion Replication

2020 ◽  
Author(s):  
Luca Terruzzi ◽  
Giovanni Spagnolli ◽  
Alberto Boldrini ◽  
Jesús R. Requena ◽  
Emiliano Biasini ◽  
...  
Keyword(s):  
Structural Data ◽  
Md Simulations ◽  
Iterative Refinement ◽  
Common Mechanism ◽  
Path Sampling ◽  
Sampling Protocol ◽  
Time Resolved ◽  
Full Reconstruction ◽  
Prion Propagation ◽  
Protein Particles

AbstractPrions are self-replicative protein particles lacking nucleic acids. Originally discovered for causing infectious neurodegenerative disorders, they have also been found to play several physiological roles in a variety of species. Functional and pathogenic prions share a common mechanism of replication, characterized by the ability of an amyloid conformer to propagate by inducing the conversion of its physiological, soluble counterpart. In this work, we focus on the propagation of the prion forming domain of HET-s, a physiological fungal prion for which high-resolution structural data are available. Since time-resolved biophysical experiments cannot yield a full reconstruction of prion replication, we resort to computational methods. To overcome the computational limitations of plain Molecular Dynamics (MD) simulations, we adopt a special type of biased dynamics called ratchet-and-pawl MD (rMD). The accuracy of this enhanced path sampling protocol strongly depends on the choice of the collective variable (CV) used to define the biasing force. Since for prion propagation a reliable reaction coordinate (RC) is not yet available, we resort to the recently developed Self-Consistent Path Sampling (SCPS). Indeed, in such an approach the CV where the biasing force is applied is not heuristically postulated but is calculated through an iterative refinement procedure. Our atomistic reconstruction of the HET-s replication shows remarkable similarities with a previously reported mechanism of mammalian PrPSc propagation obtained with a different computational protocol. Together, these results indicate that the propagation of prions generated by evolutionary distant proteins shares common features. In particular, in both these cases, prions propagate their conformation through a very similar templating mechanism.

scholarly journals Ice formation and solvent nanoconfinement in protein crystals

IUCrJ ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 346-356 ◽  
Author(s):  
David W. Moreau ◽  
Hakan Atakisi ◽  
Robert E. Thorne
Keyword(s):  
Protein Structure ◽  
Thick Layer ◽  
Structural Data ◽  
Model Systems ◽  
Host Protein ◽  
Protein Crystals ◽  
Ice Formation ◽  
Data Sets ◽  
Time Resolved ◽  
X Ray

Ice formation within protein crystals is a major obstacle to the cryocrystallographic study of protein structure, and has limited studies of how the structural ensemble of a protein evolves with temperature in the biophysically interesting range from ∼260 K to the protein–solvent glass transition near 200 K. Using protein crystals with solvent cavities as large as ∼70 Å, time-resolved X-ray diffraction was used to study the response of protein and internal solvent during rapid cooling. Solvent nanoconfinement suppresses freezing temperatures and ice-nucleation rates so that ice-free, low-mosaicity diffraction data can be reliably collected down to 200 K without the use of cryoprotectants. Hexagonal ice (Ih) forms in external solvent, but internal crystal solvent forms stacking-disordered ice (Isd) with a near-random stacking of cubic and hexagonal planes. Analysis of powder diffraction from internal ice and single-crystal diffraction from the host protein structure shows that the maximum crystallizable solvent fraction decreases with decreasing crystal solvent-cavity size, and that an ∼6 Å thick layer of solvent adjacent to the protein surface cannot crystallize. These results establish protein crystals as excellent model systems for the study of nanoconfined solvent. By combining fast cooling, intense X-ray beams and fast X-ray detectors, complete structural data sets for high-value targets, including membrane proteins and large complexes, may be collected at ∼220–240 K that have much lower mosaicities and comparableBfactors, and that may allow more confident identification of ligand binding than in current cryocrystallographic practice.

scholarly journals TIME-RESOLVED IMAGING SPECTROSCOPY OF PLANT ADAPTATIONS TO CHANGES IN THE LIGHT ENVIRONMENT AND APPLICABILITY TO SCREENING MUTANTS

HortScience ◽  
1994 ◽  
Vol 29 (4) ◽  
pp. 249b-249
Author(s):  
Sylvain L. Dubé ◽  
John F. Allen
Keyword(s):  
Energy Balance ◽  
Physiological State ◽  
Imaging Spectroscopy ◽  
State Transitions ◽  
Time Resolved ◽  
Growth And Survival ◽  
Plant Adaptations ◽  
Physico Chemical ◽  
Time Resolved Imaging ◽  
Kinetics Of

Photosynthesis, a major determinant in growth and survival of plants, is very sensitive to the energy balance of the processes triggered by the physico-chemical environment. It is, therefore, an excellent indicator of the plants' physiological state. Fundamental events in photosynthesis can be studied non-invasively and non-destructively by examining there-emission of absorbed light energy as chlorophyll a fluorescence. In this study we present digitized consecutive images of fluorescence of intact leaves of Arabidopsis sp. The relative intensity and kinetics of fluorescence of several AOI (areas of interests) of each image have been analyzed and compared. We demonstrate the feasibility of this technique for studying the physiology of light adaptations (state-transitions) of several organisms simultaneously and its applicability in indentifying mutants. Implications of this technique to the horticulture industry will be discussed.

A temperature-jump technique for time-resolved cryo-transmission Electron Microscopy

1989 ◽  
Vol 47 ◽  
pp. 742-743
Author(s):  
H. Chestnut ◽  
D. P. Siegel ◽  
J. L. Burns ◽  
Y. Talmon
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Liquid Crystalline ◽  
Temperature Jump ◽  
Specimen Preparation ◽  
Thin Specimen ◽  
Time Resolved ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Focused Beam

Transmission electron microscopy of rapidly-frozen, hydrated specimens (cryo-TEM) is a powerful way of examining labile microstructures. This technique avoids some artifacts associated with conventional preparative methods. Use of a controlled environment vitrification system (CEVS) for specimen preparation reduces the risk of unwanted sample changes due to evaporation, and permits the examination of specimens vitrified from a defined temperature. Studies of dynamic processes with time resolution on the order of seconds, in which the process was initiated by changes in sample pH, have been conducted. We now report the development of an optical method for increasing specimen temperature immediately before vitrification. Using our method, processes that are regulated by temperature can be initiated in less than 500 msec on the specimen grid. The ensuing events can then be captured by plunge-freezing within an additional 200 msec.Dimyristoylphosphatidylcholine (DMPC) liposomes, produced by extrusion, were used as test specimens. DMPC undergoes a gel/liquid crystalline transition at 24°C, inducing a change in liposome morphology from polyhedral to spherical. Five-μl aliquots of DMPC dispersions were placed on holey-carbon-filmed copper grids mounted in the CEVS environmental chamber, and maintained at 6-8°C and 80% relative humidity. Immediately before the temperature jump most of the sample was blotted away with filter paper, leaving a thin specimen film on the grid. Upon pressing the trigger, an electronic control circuit generated this timed sequence of events. First, a solenoid-activated shutter was opened to heat the specimen by exposing it for a variable time to the focused beam of a 75W Xenon arc lamp. Simultaneously, a solenoid-activated cryogen shutter in the bottom of the CEVS was opened. Next, the lamp shutter was closed after the desired heating interval. Finally, a solenoid-activated cable release was used to trigger a spring-loaded plunger in the CEVS, propelling the sample into a reservoir of liquid ethane. Vitrified samples were subsequently transferred to a Zeiss EM902 TEM, operated in zero-loss brightfield mode, for examination at −163°C.

Spectral Characterizations of Lanthanide Interactions with Thylakoid Membrane Surfaces

1995 ◽  
pp. 2185-2188
Author(s):  
Kerry K. Karukstis ◽  
Marie Y. Kao ◽  
Daniel A. Savin ◽  
Rachel A. Bittker ◽  
Karla J. Kaphengst ◽  
...  
Keyword(s):  
Thylakoid Membrane ◽  
Membrane Surfaces ◽  
Spectral Characterizations
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