scholarly journals Catalytic polymersomes to produce strong and long-lasting bioluminescence

Nanoscale ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 66-70
Author(s):  
Claire Elsa Meyer ◽  
Ioana Craciun ◽  
Cora-Ann Schoenenberger ◽  
Riccardo Wehr ◽  
Cornelia Gabriela Palivan
Keyword(s):  
Light Signal ◽  
Enzyme Protection

Polymersome-based bioluminescent nanocompartment to achieve enzyme protection and switch kinetics to produce a persistent light signal.

Effect of Calcium ion on the interaction between Thrombin and Heparin. Thermal Denaturation

1977 ◽  
Vol 38 (03) ◽  
pp. 0677-0684 ◽  
Author(s):  
Raymund Machovich ◽  
Péter Arányi
Keyword(s):  
Calcium Ions ◽  
Rate Constants ◽  
Thermal Denaturation ◽  
Time Course ◽  
Complex Analysis ◽  
Heat Inactivation ◽  
Second Phase ◽  
Denaturation Kinetics ◽  
Enzyme Protection ◽  
Enzyme Denaturation

SummaryHeat inactivation of thrombin at 54° C followed first order kinetics with a rate constant of 1.0 min−1 approximately. Addition of heparin resulted in protection against thermal denaturation and, at the same time, rendered denaturation kinetics more complex. Analysis of the biphasic curve of heat inactivation in the presence of heparin revealed that the rate constants of the second phase changed systematically with heparin concentrations. Namely, at 4.5 × 10−6M, 9 × 10−6M, 1.8 × 10−5M and 3.6 × 10−5M heparin concentrations, the rate constants were 0.27 min−1, 0.17 min−1, 0.11 min−1 and 0.06 min−1, respectively.Sulfate as well as phosphate ions displayed also enzyme protection against heat inactivation, however, the same effect was obtained already at a heparin concentration, lower by three orders of magnitude.The kinetics of enzyme denaturation was not affected by calcium ions, whereas in the presence of heparin the inactivation rate of thrombin changed, i. e. calcium ions abolished the biphasic character of time course of thermal denaturation.Thus, the data suggest that calcium ions contribute to the effect of heparin on thrombin.

scholarly journals A Novel Thin-Film Technique to Improve Accuracy of Fluorescence-Based Estimates for Periphytic Biofilms

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1464
Author(s):  
Leon Katona ◽  
Yvonne Vadeboncoeur ◽  
Christopher T. Nietch ◽  
Katie Hossler
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Light Attenuation ◽  
Pulse Amplitude ◽  
Light Signal ◽  
Photosynthetic Parameters ◽  
Pam Fluorometry ◽  
Attenuation Coefficients ◽  
Thin Film Technique ◽  
Relative Errors

Recent studies suggest that photophysiological parameters for intact substrates with depth (e.g., periphytic biofilms, microphytobenthos) are overestimated by pulse-amplitude modulated (PAM) fluorometry. This overestimation results from depth-integration effects, following the activation of deeper photosynthesizing layers by an attenuated light signal. To mitigate this error, we propose a novel slide-based thin-film technique in which fluorescence is measured on a vertically representative subsample of the biofilm, spread evenly on a microscope slide. We compared bias and precision for photosynthetic parameters estimated through conventional PAM fluorometry on intact biofilms and through our novel slide-based technique, both theoretically and empirically. Numerical simulations confirmed the consistent overestimation of key parameters for intact biofilms, with relative errors up to 145%, compared to, at most, 52% on thin films. Paired empirical observations likewise demonstrated that estimates based on intact biofilms were consistently higher (up to 248%, p<0.001) than estimates from thin films. Numerical simulation suggested greater precision with the slide-based technique for homogeneous biofilms, but potentially less precision for heterogeneous biofilms with improper subsampling. Our empirical comparison, however, demonstrated some improvement in precision with the slide-based technique (e.g., the coefficient of variation for the maximum electron transport rate was reduced 30%, p=0.009). We recommend the use of the slide-based technique, particularly for biofilms that are thick or have small light attenuation coefficients. Care should be taken, however, to obtain vertically representative subsamples of the biofilm for measurement.

scholarly journals Transcriptome Analysis of Light-Regulated Monoterpenes Biosynthesis in Leaves of Mentha canadensis L.

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 930
Author(s):  
Xu Yu ◽  
Xiwu Qi ◽  
Shumin Li ◽  
Hailing Fang ◽  
Yang Bai ◽  
...  
Keyword(s):  
Essential Oil ◽  
Transcriptome Analysis ◽  
Average Length ◽  
Glandular Trichomes ◽  
Signal Transduction Pathway ◽  
Glandular Trichome ◽  
Light Treatment ◽  
Light Signal ◽  
Environmental Aspect ◽  
Underlying Mechanisms

Light is a key environmental aspect that regulates secondary metabolic synthesis. The essential oil produced in mint (Mentha canadensis L.) leaves is used widely in the aromatics industry and in medicine. Under low-light treatment, significant reductions in peltate glandular trichome densities were observed. GC-MS analysis showed dramatically reduced essential oil and menthol contents. Light affected the peltate glandular trichomes’ development and essential oil yield production. However, the underlying mechanisms of this regulation were elusive. To identify the critical genes during light-regulated changes in oil content, following a 24 h darkness treatment and a 24 h recovery light treatment, leaves were collected for transcriptome analysis. A total of 95,579 unigenes were obtained, with an average length of 754 bp. About 56.58% of the unigenes were annotated using four public protein databases: 10,977 differentially expressed genes (DEGs) were found to be involved in the light signaling pathway and monoterpene synthesis pathway. Most of the TPs showed a similar expression pattern: downregulation after darkness treatment and upregulation after the return of light. In addition, the genes involved in the light signal transduction pathway were analyzed. A series of responsive transcription factors (TFs) were identified and could be used in metabolic engineering as an effective strategy for increasing essential oil yields.

scholarly journals Neurospora crassa Light Signal Transduction Is Affected by ROS

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Tatiana A. Belozerskaya ◽  
Natalia N. Gessler ◽  
Elena P. Isakova ◽  
Yulia I. Deryabina
Keyword(s):  
Neurospora Crassa ◽  
Zinc Fingers ◽  
White Collar ◽  
Photochemical Activity ◽  
Light Signal ◽  
Pas Domain ◽  
Light Responses ◽  
Expression Of Genes ◽  
Heterodimeric Complex ◽  
Light Signals

In the ascomycete fungus Neurospora crassa blue-violet light controls the expression of genes responsible for differentiation of reproductive structures, synthesis of secondary metabolites, and the circadian oscillator activity. A major photoreceptor in Neurospora cells is WCC, a heterodimeric complex formed by the PAS-domain-containing polypeptides WC-1 and WC-2, the products of genes white collar-1 and white collar-2. The photosignal transduction is started by photochemical activity of an excited FAD molecule noncovalently bound by the LOV domain (a specialized variant of the PAS domain). The presence of zinc fingers (the GATA-recognizing sequences) in both WC-1 and WC-2 proteins suggests that they might function as transcription factors. However, a critical analysis of the phototransduction mechanism considers the existence of residual light responses upon absence of WCC or its homologs in fungi. The data presented point at endogenous ROS generated by a photon stimulus as an alternative input to pass on light signals to downstream targets.

Reciprocal inhibition of voltage-gated potassium currents (IK(V)) by activation of cannabinoid CB1and dopamine D1receptors in ON bipolar cells of goldfish retina

2005 ◽  
Vol 22 (1) ◽  
pp. 55-63 ◽  
Author(s):  
SHIH-FANG FAN ◽  
STEPHEN YAZULLA
Keyword(s):  
G Protein ◽  
Receptor Agonist ◽  
Lucifer Yellow ◽  
Reciprocal Inhibition ◽  
Receptor Activation ◽  
Light Signal ◽  
Bipolar Cells ◽  
Protein G ◽  
Calcium Dependent ◽  
Voltage Dependent

Cannabinoid CB1receptor (viaGs) and dopamine D2receptor (viaGi/o) antagonistically modulate goldfish cone membrane currents. As ON bipolar cells have CB1and D1receptors, but not D2receptors, we focused on whether CB1receptor agonist and dopamine interact to modulate voltage-dependent outward membrane K+currentsIK(V)of the ON mixed rod/cone (Mb) bipolar cells. Whole-cell currents were recorded from Mb bipolar cells in goldfish retinal slices. Mb bipolar cells were identified by intracellular filling with Lucifer yellow. The bath solution was calcium-free and contained 1 mM cobalt to block indirect calcium-dependent effects. Dopamine (10 μM) consistently increasedIK(V)by a factor of 1.57 ± 0.12 (S.E.M.,n= 15). A CB receptor agonist, WIN 55212-2 (0.25–1 μM), had no effect, but 4 μM WIN 55212-2 suppressedIK(V)by 60%. IfIK(V)was first increased by 10 μM dopamine, application of WIN 55212-2 (0.25–1 μM) reversibly blocked the effect of dopamine even though these concentrations of WIN 55212-2 had no effect of their own. If WIN 55212-2 was applied first and dopamine (10 μM) was added to the WIN-containing solution, 0.1 μM WIN 55212-2 blocked the effect of dopamine. All effects of WIN 55212-2 were blocked by coapplication of SR 141716A (CB1antagonist) and pretreatment with pertussis toxin (blocker of Gi/o) indicating actionviaCB1receptor activation of G protein Gi/o. Coactivation of CB1and D1receptors on Mb bipolar cells produces reciprocal effects onIK(V). The CB1-evoked suppression ofIK(V)is mediated by G protein Gi/o, whereas the D1-evoked enhancement is mediated by G protein Gs. As dopamine is a retinal “light” signal, these data support our notion that endocannabinoids function as a “dark” signal, interacting with dopamine to set retinal sensitivity.

Light Signal Transduction in Higher Plants

2004 ◽  
Vol 38 (1) ◽  
pp. 87-117 ◽  
Author(s):  
Meng Chen ◽  
Joanne Chory ◽  
Christian Fankhauser
Keyword(s):  
Signal Transduction ◽  
Higher Plants ◽  
Light Signal ◽  
Light Signal Transduction

scholarly journals Gravitational wave detectors with broadband high frequency sensitivity

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Michael A. Page ◽  
Maxim Goryachev ◽  
Haixing Miao ◽  
Yanbei Chen ◽  
Yiqiu Ma ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
White Light ◽  
High Frequency ◽  
Phononic Crystal ◽  
Optical Power ◽  
Light Signal ◽  
Acoustic Cavity ◽  
Silicon Nitride Membrane ◽  
Gravitational Wave Detectors ◽  
Crystal Quartz

AbstractGravitational waves from the neutron star coalescence GW170817 were observed from the inspiral, but not the high frequency postmerger nuclear matter motion. Optomechanical white light signal recycling has been proposed for achieving broadband sensitivity in gravitational wave detectors, but has been reliant on development of suitable ultra-low loss mechanical components. Here we show demonstrated optomechanical resonators that meet loss requirements for a white light signal recycling interferometer with strain sensitivity below 10−24 Hz−1/2 at a few kHz. Experimental data for two resonators are combined with analytic models of interferometers similar to LIGO to demonstrate enhancement across a broader band of frequencies versus dual-recycled Fabry-Perot Michelson detectors. Candidate resonators are a silicon nitride membrane acoustically isolated by a phononic crystal, and a single-crystal quartz acoustic cavity. Optical power requirements favour the membrane resonator, while thermal noise performance favours the quartz resonator. Both could be implemented as add-on components to existing detectors.

Measuring clock jitter and data signals for bit error detection in optical transceiver systems

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mahmoud M. A. Eid ◽  
Ahmed Nabih Zaki Rashed ◽  
Md. Anowar Kabir ◽  
Md. Mehedi Hassan
Keyword(s):  
Error Detection ◽  
Pulse Generator ◽  
Signal Amplitude ◽  
Electrical Signal ◽  
Light Signal ◽  
Eye Diagram ◽  
Clock Jitter ◽  
Low Pass ◽  
Sequence Generator ◽  
Histogram Feature

AbstractThis work demonstrates how to measure jitter using the eye diagram Analyzer histogram feature. Bit sequence generator is employed with the NRZ Pulse generator with the electrical jitter in order to measure the signal amplitude level. We have modulated the light signal from CW Laser with the electrical signal by Mach-Zehnder Modulator through 5 km fiber cables. The signal can be amplified with a gain of 7 dB with the presence of transimpedence amplifier. The combination of electrical signal and signal from noise source can be filtered by using the low pass Gaussian filter.

The Design of the Solar Panels Automatic Tracking Controller

2014 ◽  
Vol 953-954 ◽  
pp. 123-127
Author(s):  
Rong Xia Sun ◽  
Xiao Ning Sun ◽  
Shuo Nan Wang
Keyword(s):  
Control Device ◽  
Light Signal ◽  
Control Circuit ◽  
Signal Acquisition ◽  
Single Chip ◽  
Level Control ◽  
Physical Test ◽  
Automatic Tracking ◽  
Tracking Controller ◽  
Driving Circuit

In this paper, the design is with the single chip microcomputer as the core of automatic tracking controller. The system is mainly composed of the signal acquisition part, the signal conditioning part, a control circuit and a drive circuit. The signal collection circuit composed of photosensitive resistance sensors to collect light signal, signal conversion circuit with voltage follower LM324 convert the change of light intensity to the change of the voltage, through the voltage comparator LM393 produce high and low level control stepping motor rotation; Control circuit use the AT89S52 as the main control device, output different control signals to the driving circuit; Driving circuit use the ULN2003 as driver stepper motor. Is obtained by simulation debugging, physical test, the error rate is less than 5%, in order to realize the efficient utilization of solar energy.

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