scholarly journals Differing biophysical properties underpin the unique signaling potentials within the plant phytochrome photoreceptor families

2021 ◽  
Vol 118 (22) ◽  
pp. e2105649118
Author(s):  
E. Sethe Burgie ◽  
Zachary T. K. Gannam ◽  
Katrice E. McLoughlin ◽  
Christopher D. Sherman ◽  
Alex S. Holehouse ◽  
...  
Keyword(s):  
Expression Patterns ◽  
Red Light ◽  
Strong Temperature Dependence ◽  
Turnover Rates ◽  
Biophysical Properties ◽  
Low Light ◽  
Temperature Perception ◽  
The Core ◽  
Light Fluence ◽  
Order Of Magnitude

Many aspects of photoperception by plants and microorganisms are initiated by the phytochrome (Phy) family of photoreceptors that detect light through interconversion between red light- (Pr) and far-red light-absorbing (Pfr) states. Plants synthesize a small family of Phy isoforms (PhyA to PhyE) that collectively regulate photomorphogenesis and temperature perception through redundant and unique actions. While the selective roles of these isoforms have been partially attributed to their differing abundances, expression patterns, affinities for downstream partners, and turnover rates, we show here from analysis of recombinant Arabidopsis chromoproteins that the Phy isoforms also display distinct biophysical properties. Included are a hypsochromic shift in the Pr absorption for PhyC and varying rates of Pfr to Pr thermal reversion, part of which can be attributed to the core photosensory module in each. Most strikingly, PhyB combines strong temperature dependence of thermal reversion with an order-of-magnitude faster rate to likely serve as the main physiological thermosensor, whereby thermal reversion competes with photoconversion. In addition, comparisons of Pfr occupancies for PhyA and PhyB under a range of red- and white-light fluence rates imply that low-light environments are effectively sensed by PhyA, while high-light environments, such as full sun, are effectively sensed by PhyB. Parallel analyses of the Phy isoforms from potato and maize showed that the unique features within the Arabidopsis family are conserved, thus indicating that the distinct biophysical properties among plant Phy isoforms emerged early in Phy evolution, likely to enable full interrogation of their light and temperature environments.

scholarly journals Megaparsec-scale structure around the protocluster core SPT2349–56 at z = 4.3

2020 ◽  
Vol 495 (3) ◽  
pp. 3124-3159 ◽  
Author(s):  
Ryley Hill ◽  
Scott Chapman ◽  
Douglas Scott ◽  
Yordanka Apostolovski ◽  
Manuel Aravena ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Far Infrared ◽  
Main Structure ◽  
Star Forming ◽  
Galaxy Groups ◽  
The Core ◽  
Order Of Magnitude ◽  
Number Counts ◽  
Limited Coverage

ABSTRACT We present an extensive ALMA spectroscopic follow-up programme of the $z\, {=}\, 4.3$ structure SPT2349–56, one of the most actively star-forming protocluster cores known, to identify additional members using their [C ii] 158 μm and CO(4–3) lines. In addition to robustly detecting the 14 previously published galaxies in this structure, we identify a further 15 associated galaxies at $z\, {=}\, 4.3$, resolving 55$\, {\pm }\,$5 per cent of the 870 μm flux density at 0.5 arcsec resolution compared to 21 arcsec single-dish data. These galaxies are distributed into a central core containing 23 galaxies extending out to 300 kpc in diameter, and a northern extension, offset from the core by 400 kpc, containing three galaxies. We discovered three additional galaxies in a red Herschel-SPIRE source 1.5 Mpc from the main structure, suggesting the existence of many other sources at the same redshift as SPT2349–56 that are not yet detected in the limited coverage of our data. An analysis of the velocity distribution of the central galaxies indicates that this region may be virialized with a mass of (9$\pm 5)\, {\times }\, 10^{12}$  M⊙, while the two offset galaxy groups are about 30 and 60 per cent less massive and show significant velocity offsets from the central group. We calculate the [C ii] and far-infrared number counts, and find evidence for a break in the [C ii] luminosity function. We estimate the average SFR density within the region of SPT2349–56 containing single-dish emission (a proper diameter of 720 kpc), assuming spherical symmetry, to be roughly 4$\, {\times }\, 10^4$ M⊙ yr−1 Mpc−3; this may be an order of magnitude greater than the most extreme examples seen in simulations.

Photodynamic Therapy at Low-Light Fluence Rate: in vitro Assays on Colon Cancer Cells

2019 ◽  
Vol 25 (1) ◽  
pp. 1-6 ◽  
Author(s):  
J. A. Rodrigues ◽  
R. Amorim ◽  
M. F. Silva ◽  
F. Baltazar ◽  
R. F. Wolffenbuttel ◽  
...  
Keyword(s):  
Colon Cancer ◽  
Photodynamic Therapy ◽  
Cancer Cells ◽  
Fluence Rate ◽  
Colon Cancer Cells ◽  
Low Light ◽  
Light Fluence

scholarly journals Limit cycle dynamics can guide the evolution of gene regulatory networks towards point attractors

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Stuart P. Wilson ◽  
Sebastian S. James ◽  
Daniel J. Whiteley ◽  
Leah A. Krubitzer
Keyword(s):  
Gene Expression ◽  
Limit Cycles ◽  
Gene Networks ◽  
Regulatory Networks ◽  
Expression Patterns ◽  
Specific Gene ◽  
Boolean Models ◽  
A Genome ◽  
Order Of Magnitude ◽  
Accelerate Evolution

AbstractDevelopmental dynamics in Boolean models of gene networks self-organize, either into point attractors (stable repeating patterns of gene expression) or limit cycles (stable repeating sequences of patterns), depending on the network interactions specified by a genome of evolvable bits. Genome specifications for dynamics that can map specific gene expression patterns in early development onto specific point attractor patterns in later development are essentially impossible to discover by chance mutation alone, even for small networks. We show that selection for approximate mappings, dynamically maintained in the states comprising limit cycles, can accelerate evolution by at least an order of magnitude. These results suggest that self-organizing dynamics that occur within lifetimes can, in principle, guide natural selection across lifetimes.

scholarly journals GRID-SITES: Gridded Solar Iterative Temperature Emission Solver for Fast DEM Inversion

Solar Physics ◽  
2019 ◽  
Vol 294 (10) ◽  
Author(s):  
James Pickering ◽  
Huw Morgan
Keyword(s):  
Emission Measure ◽  
Inversion Method ◽  
Multiple Channels ◽  
Differential Emission Measure ◽  
The Core ◽  
Data Inversion ◽  
Core Method ◽  
Input Dataset ◽  
Order Of Magnitude ◽  
General Measurement

Abstract The increasing size of solar datasets demands highly efficient and robust analysis methods. This paper presents an approach that can increase the computational efficiency of differential emission measure (DEM) inversions by an order of magnitude or higher, with the efficiency factor increasing with the size of the input dataset. The method, named the Gridded Solar Iterative Temperature Emission Solver (Grid-SITES) is based on grouping pixels according to the similarity of their intensities in multiple channels, and solving for one DEM per group. This is shown to be a valid approach, given a sufficiently high number of grid bins for each channel. The increase in uncertainty arising from the quantisation of the input data is small compared to the general measurement and calibration uncertainties. In this paper, we use the Solar Iterative Temperature Emission Solver (SITES) as the core method for the DEM inversion, although Grid-SITES provides a general framework which may be used with any DEM inversion method, or indeed any large multi-dimensional data inversion problem. The method is particularly efficient for processing larger images, offering a factor of 30 increase in speed for a 10 megapixel image. For a time series of observations, the gridded results can be passed sequentially to each new image, with new populated bins added as required. This process leads to increasing efficiency with each new image, with potential for a ${\approx\,}100$≈100 increase in efficiency dependent on the size of the images.

scholarly journals TLD1433-Mediated Photodynamic Therapy with an Optical Surface Applicator in the Treatment of Lung Cancer Cells In Vitro

2020 ◽  
Vol 13 (7) ◽  
pp. 137 ◽  
Author(s):  
Sarah Chamberlain ◽  
Houston D. Cole ◽  
John Roque ◽  
David Bellnier ◽  
Sherri A. McFarland ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Photodynamic Therapy ◽  
Cell Viability ◽  
Light Propagation ◽  
Residual Disease ◽  
Red Light ◽  
Optical Surface ◽  
Light Fluence ◽  
532 Nm

Intra-operative photodynamic therapy (IO-PDT) in combination with surgery for the treatment of non-small cell lung cancer and malignant pleural mesothelioma has shown promise in improving overall survival in patients. Here, we developed a PDT platform consisting of a ruthenium-based photosensitizer (TLD1433) activated by an optical surface applicator (OSA) for the management of residual disease. Human lung adenocarcinoma (A549) cell viability was assessed after treatment with TLD1433-mediated PDT illuminated with either 532- or 630-nm light with a micro-lens laser fiber. This TLD1433-mediated PDT induced an EC50 of 1.98 μM (J/cm2) and 4807 μM (J/cm2) for green and red light, respectively. Cells were then treated with 10 µM TLD1433 in a 96-well plate with the OSA using two 2-cm radial diffusers, each transmitted 532 nm light at 50 mW/cm for 278 s. Monte Carlo simulations of the surface light propagation from the OSA computed light fluence (J/cm2) and irradiance (mW/cm2) distribution. In regions where 100% loss in cell viability was measured, the simulations suggest that >20 J/cm2 of 532 nm was delivered. Our studies indicate that TLD1433-mediated PDT with the OSA and light simulations have the potential to become a platform for treatment planning for IO-PDT.

scholarly journals Role of blue and red light in stomatal dynamic behaviour

2019 ◽  
Vol 71 (7) ◽  
pp. 2253-2269 ◽  
Author(s):  
Jack S A Matthews ◽  
Silvere Vialet-Chabrand ◽  
Tracy Lawson
Keyword(s):  
Blue Light ◽  
Red Light ◽  
Light Response ◽  
Early Morning ◽  
Stomatal Opening ◽  
Carbon Gain ◽  
Blue Light Response ◽  
Order Of Magnitude ◽  
Photosynthetic Responses ◽  
Novel Target

Abstract Plants experience changes in light intensity and quality due to variations in solar angle and shading from clouds and overlapping leaves. Stomatal opening to increasing irradiance is often an order of magnitude slower than photosynthetic responses, which can result in CO2 diffusional limitations on leaf photosynthesis, as well as unnecessary water loss when stomata continue to open after photosynthesis has reached saturation. Stomatal opening to light is driven by two distinct pathways; the ‘red’ or photosynthetic response that occurs at high fluence rates and saturates with photosynthesis, and is thought to be the main mechanism that coordinates stomatal behaviour with photosynthesis; and the guard cell-specific ‘blue’ light response that saturates at low fluence rates, and is often considered independent of photosynthesis, and important for early morning stomatal opening. Here we review the literature on these complicated signal transduction pathways and osmoregulatory processes in guard cells that are influenced by the light environment. We discuss the possibility of tuning the sensitivity and magnitude of stomatal response to blue light which potentially represents a novel target to develop ideotypes with the ‘ideal’ balance between carbon gain, evaporative cooling, and maintenance of hydraulic status that is crucial for maximizing crop performance and productivity.

High Rayleigh number thermal convection in a shallow laterally heated cavity

1993 ◽  
Vol 440 (1909) ◽  
pp. 273-289 ◽  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Rayleigh Number ◽  
Hadley Circulation ◽  
Large Contribution ◽  
The Core ◽  
Vertical Boundary ◽  
Order Of Magnitude ◽  
End Wall ◽  
Lateral Heat

The flow near the end of a shallow laterally heated cavity enters a nonlinear convective régime when the Rayleigh number R , based on cavity height, is of the same order of magnitude as the aspect ratio L (length/height). In the present work the asymptotic structure of the flow that develops in the limit as is R/L →∞ considered for the case where the horizontal surfaces of the cavity are thermally insulated. A model is discussed in which the formation of a vertical boundary layer on the end wall involves an unexpectedly large contribution to the local ambient temperature field. Expulsion of fluid from the base of the layer, and its subsequent return to the core through a horizontal boundary layer, maintains the necessary lateral heat transfer in the cavity. Implications of the model for the flow throughout the cavity are also discussed. The evolution of the end-zones leads to a change in the amplitude of the main Hadley circulation when R = O ( L 12/7 ). Various properties of the solution for this new régime are determined, including the Nusselt number for the lateral heat transfer, which is found to be proportional to L 3/7 . A comparison is made with both numerical and experimental results.

Identification of preferential flow effects on hydraulic conductivity measurements using a fluorescent tracer

2000 ◽  
Vol 37 (2) ◽  
pp. 479-484
Author(s):  
Tom A Al ◽  
David W Blowes
Keyword(s):  
Hydraulic Conductivity ◽  
Measurement Errors ◽  
Preferential Flow ◽  
Conductivity Measurements ◽  
Fine Grained ◽  
The Core ◽  
Core Samples ◽  
Dye Tracer ◽  
Order Of Magnitude ◽  
Constant Head

Core samples were collected from fractured and unfractured zones within fine-grained, unconsolidated mine tailings. The hydraulic conductivity of the core samples was measured in a constant-head permeameter. A fluorescent dye tracer was added to the constant-head reservoir in the permeameter. The tests were run for approximately 48 h, then the cores were sectioned to observe the distribution of dye. Flow through the fractures results in hydraulic conductivity measurements up to one order of magnitude greater than that of unfractured tailings. Observations of the dye distribution in samples following permeameter measurements are used to identify cases where preferential flow in fractures has influenced the hydraulic conductivity measurements. The dye tracer distribution also indicates where measurement errors may be suspected due to flow leakage around the core sample.Key words: tracers, hydraulic conductivity, fractures, tailings.

scholarly journals Development of a Novel Targeting System for Lethal Photosensitization of Antibiotic-Resistant Strains of Staphylococcus aureus

2005 ◽  
Vol 49 (9) ◽  
pp. 3690-3696 ◽  
Author(s):  
Michelle L. Embleton ◽  
Sean P. Nair ◽  
Wendy Heywood ◽  
Dev C. Menon ◽  
Barry D. Cookson ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Agents ◽  
Red Light ◽  
Low Light ◽  
Antibiotic Resistant ◽  
Low Concentrations ◽  
Molar Equivalent ◽  
Resistant Strains ◽  
Covalently Linked ◽  
Host Tissues

ABSTRACT Light-activated antimicrobial agents (photosensitizers) are promising alternatives to antibiotics for the treatment of topical infections. To improve efficacy and avoid possible damage to host tissues, targeting of the photosensitizer to the infecting organism is desirable, and this has previously been achieved using antibodies and chemical modification of the agent. In this study we investigated the possibility of using a bacteriophage to deliver the photosensitizer tin(IV) chlorin e6 (SnCe6) to Staphylococcus aureus. SnCe6 was covalently linked to S. aureus bacteriophage 75, and the ability of the conjugate to kill various strains of S. aureus when exposed to red light was determined. Substantial kills of methicillin- and vancomycin-intermediate strains of S. aureus were achieved using low concentrations of the conjugate (containing 1.5 μg/ml SnCe6) and low light doses (21 J/cm2). Under these conditions, the viability of human epithelial cells (in the absence of bacteria) was largely unaffected. On a molar equivalent basis, the conjugate was a more effective bactericide than the unconjugated SnCe6, and killing was not growth phase dependent. The conjugate was effective against vancomycin-intermediate strains of S. aureus even after growth in vancomycin. The results of this study have demonstrated that a bacteriophage can be used to deliver a photosensitizer to a target organism, resulting in enhanced and selective killing of the organism. Such attributes are desirable in an agent to be used in the photodynamic therapy of infectious diseases.

scholarly journals Measurement of Cyanine Dye Photobleaching in Photosensitizer Cyanine Dye Conjugates Could Help in Optimizing Light Dosimetry for Improved Photodynamic Therapy of Cancer

Molecules ◽  
2018 ◽  
Vol 23 (8) ◽  
pp. 1842 ◽  
Author(s):  
Nadine James ◽  
Ravindra Cheruku ◽  
Joseph Missert ◽  
Ulas Sunar ◽  
Ravindra Pandey
Keyword(s):  
Photodynamic Therapy ◽  
Fluorescence Imaging ◽  
Tumor Response ◽  
Cyanine Dye ◽  
Fluence Rate ◽  
Low Light ◽  
Light Dosimetry ◽  
Light Fluence ◽  
Photodynamic Therapy Of Cancer

Photodynamic therapy (PDT) of cancer is dependent on three primary components: photosensitizer (PS), light and oxygen. Because these components are interdependent and vary during the dynamic process of PDT, assessing PDT efficacy may not be trivial. Therefore, it has become necessary to develop pre-treatment planning, on-line monitoring and dosimetry strategies during PDT, which become more critical for two or more chromophore systems, for example, PS-CD (Photosensitizer-Cyanine dye) conjugates developed in our laboratory for fluorescence-imaging and PDT of cancer. In this study, we observed a significant impact of variable light dosimetry; (i) high light fluence and fluence rate (light dose: 135 J/cm2, fluence rate: 75 mW/cm2) and (ii) low light fluence and fluence rate (128 J/cm2 and 14 mW/cm2 and 128 J/cm2 and 7 mW/cm2) in photobleaching of the individual chromophores of PS-CD conjugates and their long-term tumor response. The fluorescence at the near-infrared (NIR) region of the PS-NIR fluorophore conjugate was assessed intermittently via fluorescence imaging. The loss of fluorescence, photobleaching, caused by singlet oxygen from the PS was mapped continuously during PDT. The tumor responses (BALB/c mice bearing Colon26 tumors) were assessed after PDT by measuring tumor sizes daily. Our results showed distinctive photobleaching kinetics rates between the PS and CD. Interestingly, compared to higher light fluence, the tumors exposed at low light fluence showed reduced photobleaching and enhanced long-term PDT efficacy. The presence of NIR fluorophore in PS-CD conjugates provides an opportunity of fluorescence imaging and monitoring the photobleaching rate of the CD moiety for large and deeply seated tumors and assessing PDT tumor response in real-time.

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