Found 297 results
Article
13 March 2023Design of Oscillatory Networks through Post-Translational Control of Network Components
Many essential functions in biological systems, including cell cycle progression and circadian rhythm regulation, are governed by the periodic behaviors of specific molecules. These periodic behaviors arise from the precise arrangement of components in biomolecular networks that generate oscillatory output signals. The dynamic properties of individual components of these networks, such as maturation delays and degradation rates, often play a key role in determining the network's oscillatory behavior. In this study, we explored the post-translational modulation of network components as a means to generate genetic circuits with oscillatory behaviors and perturb the oscillation features. Specifically, we used the NanoDeg platform—A bifunctional molecule consisting of a target-specific nanobody and a degron tag—to control the degradation rates of the circuit’s components and predicted the effect of NanoDeg-mediated post-translational depletion of a key circuit component on the behavior of a series of proto-oscillating network topologies. We modeled the behavior of two main classes of oscillators, namely relaxation oscillator topologies (the activator-repressor and the Goodwin oscillator) and ring oscillator topologies (repressilators). We identified two main mechanisms by which non-oscillating networks could be induced to oscillate through post-translational modulation of network components: an increase in the separation of timescales of network components and mitigation of the leaky expression of network components. These results are in agreement with previous findings describing the effect of timescale separation and mitigation of leaky expression on oscillatory behaviors. This work thus validates the use of tools to control protein degradation rates as a strategy to modulate existing oscillatory signals and construct oscillatory networks. In addition, this study provides the design rules to implement such an approach based on the control of protein degradation rates using the NanoDeg platform, which does not require genetic manipulation of the network components and can be adapted to virtually any cellular protein. This work also establishes a framework to explore the use of tools for post-translational perturbations of biomolecular networks and generates desired behaviors of the network output.
Perspective
07 March 2023Pulsed Ultraviolet C as a Potential Treatment for COVID-19
Currently, low dose radiotherapy (LDRT) is being tested for treating life-threatening pneumonia in COVID-19 patients. Despite the debates over the clinical use of LDRT, some clinical trials have been completed, and most are still ongoing. Ultraviolet C (UVC) irradiation has been proven to be highly efficient in inactivating the coronaviruses, yet is considerably safer than LDRT. This makes UVC an excellent candidate for treating COVID-19 infection, especially in case of severe pneumonia as well as the post COVID-19 pulmonary fibrosis. However, the major challenge in using UVC is its delivery to the lungs, the target organ of COVID-19, due to its low penetrability through biological tissues. We propose to overcome this challenge (i) by using pulsed UVC technologies which dramatically increase the penetrability of UVC through matter, and (ii) by integrating the pulsed UVC technologies into a laser bronchoscope, thus allowing UVC irradiation to reach deeper into the lungs. Although the exact characteristics of such a treatment should yet to be experimentally defined, this approach might be much safer and not less efficient than LDRT.
Article
03 March 2023SnS2 Quantum Dots Decorated MoS2 Nanosheets Enabling Efficient Photocatalytic H2 Evolution in CO2 Saturated Water
SnS2/MoS2 heterojunction nanocomposite was prepared by a one-step hydrothermal synthesis method. The nanocomposite exhibited much improved photocatalytic hydrogen evolution performance in CO2 saturated solution compared with pure MoS2 and SnS2 samples. The improved photocatalytic activity was attributed to the S-scheme heterojunction structure between SnS2 quantum dots and MoS2 nanosheets which facilitate electron-hole separation both in MoS2 and SnS2. In the S-scheme structure, the strong reduction ability of SnS2 quantum dots was well maintained for the improved H2 evolution. In situ DRIFT studies allowed us to suggest reaction pathways from CO2 and H2O to photocatalytic H2, CO, and CH4 generation.
Article
07 February 2023Production of Highly Modified C30-carotenoids with Singlet Oxygen-quenching Activities, 5-glucosyl-5,6-dihydro-4,4’-diapolycopen-4’-oic Acid, and Its Three Intermediates Using Genes from Planococcus maritimus Strain iso-3
Planococcus maritimus strain iso-3 was previously isolated from intertidal sediment in the North Sea and was found to produce a highly modified C30-carotenoid, methyl-5-glucosyl-5,6-dihydro-4,4’-diapolycopenoate, as the final product. In this study, we analyzed the function of the carotenoid terminal oxidase crtP (renamed cruO) and aldehyde dehydrogenase aldH genes in P. maritimus strain iso-3 and elucidated the carotenoid biosynthetic pathway for this strain at the gene level. We produced four novel C30-carotenoids with potent singlet oxygen-quenching activities, 5-glucosyl-5,6-dihydro-4,4’-diapolycopen-4’-oic acid and its three intermediates, which were obtained using E. coli cells carrying the cruO (and aldH) gene(s) in addition to the known P. maritimus carotenogenic genes.
Article
07 February 2023Plasmon Enhanced Nickel(II) Catalyst for Photocatalytic Lignin Model Cleavage
Photocatalytic-induced cleaving of the ether C–O bond in model lignin compounds was studied with a closely-coupled compo-site material consisting of Ni(OH)2 and gold nanoparticles (NPs) on a zirconia support (Au/ZrO2–Ni(OH)2). The three important ether bond types consisting of α-O-4, β-O-4, and 4-O-5 linkages can all be cleaved using this catalyst at reaction temperatures 40, 85 and 95 °C when under low-flux visible light irradiation. The Au NPs action as a light-harvesting antenna provided light-generated hot electrons that reduced Ni2+ to Ni0. The Ni0 was the active catalytic site where reductive cleavage of ether C–O bonds occurred while it was oxidized to Ni2+ to complete the catalysis cycle. The plasmonic antenna system with supported Ni(OH)2 exhibited better ability for the catalytic reductive ether cleavages under visible light irradiation compared to photocata-lysts of Au NPs and Ni2+ ions immobilized on alumina fibers.
Article
30 January 2023Metal-Free Lewis Pair Catalysts for a One-Pot Terpolymerization of Propylene Oxide, ʟ-Lactide and CO2
Multiblock and di-/tri-block copolymers are successfully synthesized for the first time via the metal-free terpolymerization of propylene oxide (PO), ʟ-lactide (LA) and CO2 in one-pot/one-step and one-pot/two-step protocols respectively. Firstly, triethyl borane (TEB) and bis(triphenylphosphine)iminium chloride (PPNCl) Lewis pair is employed in the ring-opening polymerization of LA, wherein the catalytic efficiency is significantly correlated to the TEB/PPNCl feed ratio. Next, a series of TEB/base pairs are selected to synthesize the PO/LA/CO2 terpolymer (PPCLA) in one-pot/one-step strategy. In PPCLA synthesis, LA exhibits the fastest reaction rate but severe transesterification is almost unavoidable, resulting in low molecular weight products. In order to prepare high-molecular-weight terpolymers, a one-pot/two-step methodology has to be applied. By this method, the copolymerization of PO/CO2 proceeds first to form poly(propylene carbonate) (PPC) macroinitiators, which triggers the polymerization of LA to polylactide (PLA), leading to PLA-PPC or PLA-PPC-PLA block copolymers. The synthesized PLA-PPC-PLA block copolymers display improved thermal stability compared with PPC.
Article
28 January 2023Current Challenges to the Sustainable Development of Rural Communities in Russia's Central Chernozem Region
The rural community system in the Central Chernozem Economic Region in Russia is undergoing a radical transformation under the interrelated influence of fundamental factors that have rendered the development of many communities unsustainable. This paper analyses the role of urbanisation processes in population changes and transformation of rural community systems in the region; determines the level of horizontal mobility among the rural population, as well as its impact on settlement evolution; assesses the share of small and extremely small communities in settlement composition; and outlines these communities’ future development prospects. The authors believe that the socio-demographic “desertification” of peripheral municipalities can pose challenges to rural development: a shortage of labour resources, changes in population quality, and problems of innovation diffusion. The study recommends improving the comfort of the living environment and accelerating the technical re-equipment and automation of agricultural production.
