Kinetic Modeling of Saccharomyces cerevisiae Central Carbon Metabolism: Achievements, Limitations, and Opportunities

Central carbon metabolism comprises the metabolic pathways in the cell that process nutrients into energy, building blocks and byproducts. To unravel the regulation of this network upon glucose perturbation, several metabolic models have been developed for the microorganism Saccharomyces cerevisiae. These dynamic representations have focused on glycolysis and answered multiple research questions, but no commonly applicable model has been presented. This review systematically evaluates the literature to describe the current advances, limitations, and opportunities. Different kinetic models have unraveled key kinetic glycolytic mechanisms. Nevertheless, some uncertainties regarding model topology and parameter values still limit the application to specific cases. Progressive improvements in experimental measurement technologies as well as advances in computational tools create new opportunities to further extend the model scale. Notably, models need to be made more complex to consider the multiple layers of glycolytic regulation and external physiological variables regulating the bioprocess, opening new possibilities for extrapolation and validation. Finally, the onset of new data representative of individual cells will cause these models to evolve from depicting an average cell in an industrial fermenter, to characterizing the heterogeneity of the population, opening new and unseen possibilities for industrial fermentation improvement.

An ultra-sensitive and easy-to-use multiplexed single-cell proteomic analysis

Proteins analysis from an average cell population often overlooks the cellular heterogeneity of expressed effector molecules, and knowledge about the regulations of key biological processes may remain obscure. Therefore, the necessity of single-cell proteomics (SCP) technologies arises. Without microfluidic chip, expensive ultrasonic equipment, or reformed liquid chromatogram (LC) system, we established an Ultra-sensitive and Easy-to-use multiplexed Single-Cell Proteomic workflow (UE-SCP). Specifically, the flexible sorting system ensured outstanding cell activity, high accuracy, remarkable efficiency, and robustness during single-cell isolation. Multiplex isobaric labeling realized the high-throughput analysis in trapped ion mobility spectrometry coupled with quadrupole time-of-flight mass spectrometry (timsTOF MS). Using this pipeline, we achieved single-cell protein quantities to a depth of over 2,000 protein groups in two human cell lines, Hela and HEK-293T. A small batch experiment can identify and quantify more than 3200 protein groups in 32 single cells, while a large batch experiment can identify and quantify about 4000 protein groups in 96 single cells. All the 128 single cells from different cell lines could been unsupervised clustered based on their proteomes. After the integration of data quality control, data cleaning, and data analysis, we are confident that our UE-SCP platform will be easy-to-marketing popularization and will promote biological applications of single-cell proteomics.

Efficiency Enhancement of Photovoltaic Module Using An Aluminum Foam Matrix Filled With Phase Change Material (PCM) Under Hot Climate Conditions

In the present work, a passive cooling strategy combining an aluminium foam matrix (AFM) with PCM was employed to regulate the temperature of a photovoltaic (PV) system The comparison between three PV modules was established ,the first one was conventional without any changes ,the second one was PV combined with PCM (PV-PCM) and the last one was PV combined with modified PCM which contain an aluminum foam matrix embedded in it (PV-PCM/AFM).Outdoor experiments were carried out in the hot weather of Benha, Egypt, which is situated at latitude 30.466° North and longitude 31.185° East. A comparison of the three PV designs was given and analysed, based on PV surface temperature, PCM temperature, open-circuit voltage, output power generated, and electrical efficiency. It was observed that using composite PCM resulted in better heat absorption from the PV module and better temperature distribution inside the PCM enclosure. Furthermore, the results indicated that against the unmodified PV system, the average cell’s temperature in the PV-PCM system was dropped by 13.3% and its electrical power was enhanced by 9%. Meanwhile, the average cell temperature in the PV-PCM/AFM configuration was reduced by 21.6% while the enhancement of the electrical power was at 14%. Furthermore, the findings demonstrated that, as compared to unmodified PCM, AFM impregnation accelerated the melting of modified PCM by roughly 37%.

Localized Peptidoglycan Biosynthesis in Chlamydia trachomatis Conforms to the Polarized Division and Cell Size Reduction Developmental Models

Cell size regulation in bacteria is a function of two basic cellular processes: the expansion of the cell envelope and its constriction at spatially defined points at what will eventually become the division plane. In most bacterial species, both cell wall expansion and restriction are dependent on peptidoglycan (PG), a structural polymer comprised of sugars and amino acids that imparts strength and rigidity to bacterial membranes. Pathogenic Chlamydia species are unique in that their cell walls contain very little PG, which is restricted almost entirely to the apparent division plane of the microbe’s replicative forms. Very little is known about the degree to which PG affects the size and shape of C. trachomatis during its division process, and recent studies suggest the process is initiated via a polarized mechanism. We conducted an imaging study to ascertain the dimensions, orientation, and relative density of chlamydial PG throughout the organism’s developmental cycle. Our analysis indicates that PG in replicating C. trachomatis can be associated with four, broad structural forms; polar/septal disks, small/thick rings, large rings, and small/thin rings. We found that PG density appeared to be highest in septal disks and small/thick rings, indicating that these structures likely have high PG synthesis to degradation ratios. We also discovered that as C. trachomatis progresses through its developmental cycle PG structures, on average, decrease in total volume, indicating that the average cell volume of chlamydial RBs likely decreases over time. When cells infected with C. trachomatis are treated with inhibitors of critical components of the microbe’s two distinct PG synthases, we observed drastic differences in the ratio of PG synthesis to degradation, as well as the volume and shape of PG-containing structures. Overall, our results suggest that C. trachomatis PG synthases differentially regulate the expansion and contraction of the PG ring during both the expansion and constriction of the microbe’s cell membrane during cell growth and division, respectively.

Production Enhancement of Human Adipose-Derived Mesenchymal Stem Cells By Low-Intensity Ultrasound Stimulation

Background: Low-intensity ultrasound (LIUS) has been used to increase the proliferation rate of various stem cells including human adipose-derived mesenchymal stem cells (hAdMSCs). hAdMSCs is now commercially produced for various therapeutic applications. The purpose of this study was to show feasibility of enhancing the productivity of cell culture during 16-day cell culturing and increasing proliferation rate of hAdMSCs by LIUS stimulation with appropriate ultrasound parameters. Methods: Beam patterns of 5 and 10 MHz ultrasound transducers were measured to confirm the area of stimulation. The intensity of sound waves transmitted through a Petri-dish was measured in situ for quantitative evaluation. Bromodeoxyuridine (BrdU) incorporation assay was performed to search for appropriate parameters for LIUS stimulation of hAdMSCs. Cell culture medium supplemented with 8% fetal bovine serum (FBS) in a 35 mm Petri-dish was used for 16 days with subculture from 2 to 6 passage. Results: A frequency of 5 MHz, an intensity of 300 , a duration of 10 minutes per day, and continuous waves with 100% duty cycle were the best parameters according to the BrdU assay of proliferation rate of hAdMSCs. LIUS stimulation group had about 3.25-fold greater number of cells from passage 2 to 6 compared with the control group. Doubling time was decreased to 4.44 hours in average. Cell viability was the same between the control and LIUS stimulation groups.Conclusions: This study of enchanced proliferation rate and cell culture productivity of hAdMSCs by LIUS stimulation may lay the foundation for the application of LIUS stimulation in cell therapeutic industry by reducing the production cost and time required for cell therapy.

Effect of rare earth nucleating agent on supercritical CO2 foaming behavior of block copolymerized polypropylene

The rare earth nucleating agent was used to modify block copolymerized polypropylene (PPB) in foaming process. The results show that the crystallization of PPB and the melting temperature of β-crystal increased gradually with increased β-crystal nucleating agent content. The total crystallinity decreased with amount of addition increasing, and the relative content of β-crystal increased first and then decreased. When β-crystal nucleating agent content was 0.4 wt%, the relative β-crystal content reached the maximum value of 95.27%, and the final crystal grain refinement significantly. The addition of rare earth β-crystal nucleating agent has a good effect on improving the uniformity of foam cells. Under the same content of β-crystal nucleating agent and pressure, the average cell diameter and expansion ratio increased with the saturation temperature increasing. After the foaming temperature reaches 155°C, the expansion ratio began to decrease, which was also consistent with the changed trend of relative β-crystal content. At the same content of temperature and relative β-crystal, as the foaming pressure increased, the cell diameter decreased gradually, and the expansion ratio increased first, and then decreased.

Biovolume Method for Foraminiferal Biomass Assessment: Evaluation of Geometric Models and Incorporation of Species Mean Cell Occupancy

ABSTRACT Foraminifers are widespread, highly abundant protists and active participants in marine carbon cycling. Their biomass might represent almost half of the total meiobenthic biomass in the deep sea. Foraminiferal biomass is frequently assessed through geometric models and biovolume estimates due to its non-destructive nature, which allows estimates of individuals from palaeoecological, museum, and living samples. To increase the accuracy of foraminiferal biovolume and biomass assessment we evaluate and propose geometric models for 207 foraminiferal taxa and the species’ average cell occupancy of the test. Individual test dimensions were measured to calculate volume (µm³), and the percent of cell occupancy (PCO) of the test was measured to assess the biovolume (µm³). These data were converted into individual biomass measurements (µg Corg ind−1). Our high intra- and interspecific PCO variance suggest that a mean PCO for each species represents the natural variability of occupancy more accurately than a predetermined fixed percentage for the whole assemblage, as previously asserted in the literature. Regression equations based on the relationship between test dimensions and volumes are presented. The geometric models, the PCO adjustment, and the equations will reduce time, effort, and discrepancies in foraminiferal biovolume and biomass assessments. Therefore, these results can improve the use and reliability of foraminiferal biomass in the future, facilitating its use in (1) distinct approaches including carbon flux estimations, (2) determining the effects of climate change on the marine trophic webs, and (3) environmental monitoring programs.

Assessment of Biosafety and Implantation Feasibility of Novel Phakic Refractive Lens

Purpose: To investigate the biosafety and implantation feasibility of newly developed phakic refractive lens (PRL) in rabbit eyes. Methods: The PRLs, including short PRL (S-PRL), large PRL (L-PRL), and large grooved PRL (LG-PRL), were prepared by molding liquid medical silicon. The in vitro cytotoxicity of the above PRLs was evaluated by incubating them with human lens epithelial cells (HLECs) and then measuring cell viability by CCK-8 assay. In vitro cell adhesion of PRLs was assessed by culturing HLECs on PRL film surface and calculating the cell number and average cell area after stained with Calcein-AM and fluorescent. The implantation feasibility was appraised by observing the relative positions of S-PRL, L-PRL or LG-PRL implanted in the posterior chamber of rabbit eyes by optical coherence tomography, and calculating their retention ratio postoperatively. The intraocular pressure (IOP) of S-PRL, L-PRL, LG-PRL and control groups of rabbit eyes was compared to evaluate the biosafety of implantation.Results: The results of in vitro cytotoxicity showed no significant difference of cell viability was observed in the S-PRL, L-PRL or LG-PRL groups compared to the control group throughout the whole experiment. The HLECs cultured on the PRL film surface presented similar cell number, but smaller average cell area (53.8% vs 100%) when compared to the control group, which implied obvious adhesion inhibition on HLECs caused by PRL film. After implantation of S-PRL, L-PRL or LG-PRL into the posterior chamber of rabbit eyes, no obvious inflammation and IOP elevation were observed at each time point in all sample groups compared to the control group, which indicated that PRL samples had good implantation biosafety. Most of the implanted L-PRL and LG-PRL kept in the correct location, while only less of the S-PRL was at the right site. That was, L-PRL and LG-PRL had proper relative position and high retention ratio in the posterior chamber of rabbit eyes. L-PRL and S-PRL samples tended to attach to iris surface, while LG-PRL sample constructed enough space on the iris surface by its grooves surrounding the central optical zone, which was conducive to circulation of aqueous humor.Conclusions: The newly developed LG-PRL sample presented good biosafety in terms of the negligible in vitro cytotoxicity, ocular inflammation and IOP fluctuations. The LG-PRL provided the best implantation feasibility due to the more proper relative position, available space for aqueous humor circulation, and high retention ratio in the posterior chamber of rabbit eyes among the three kinds of PRL samples. Thus, LG-PRL is a promising alternative with appropriate size and surface structure to more effectively correct refractive errors.

Experimental Research on Detonation Cell Size of a Purified Biogas-Oxygen Mixture

Interest in alternative and renewable energy sources has risen significantly in recent years. Biogas is a prime example of a promising, alternative fuel that might be a possible replacement for fossil fuels. It is a mixture consisting mainly of CH4 and CO2 with various additions. Biogas is easily storable and as such is a more reliable and stable source of energy than solar and wind sources, which suffer from unreliability due to their dependence on weather conditions. In this paper, the authors report experimental results of detonation of a biogas-oxygen mixture. The composition of the biogas was 70% CH4 + 30% CO2 and the experiments were carried out for a range of equivalence ratios (Φ = 0.5 ÷ 1.5) and initial pressures (0.6 ÷ 1.6 bar). The aim of the research was to analyze the cellular structure of detonation. The soot foil technique was used to determine the width of the detonation cells (λ). The conducted experiments and subsequent analysis of the detonation cell size confirm that both the increase in the initial pressure of the mixture or move away from stoichiometric (Φ = 1) composition is accompanied by a decrease in the width of the detonation cell. The authors also argue that due to the unstable cellular structure of the detonation, it is insufficient to report only the average cell size. Instead, the researchers propose more detailed statistical description assured values.

Effect of X-ray radiation on the nanomechanical properties of the erythrocyte surface of rats on a high-cholesterol diet

Objective. To reveal changes in the structural and nanomechanical properties of the erythrocyte surface caused by the action of X-ray radiation in vitro on the whole blood of rats on a high-cholesterol diet using the method of atomic-force microscopy.Materials and methods. The blood of male Wistar rats being on a high-cholesterol diet for two months was exposed to X-ray radiation (320 kV) at doses of 1 and 100 Gy. The structural, elastic and adhesive properties of the surface of isolated and glutaraldehyde-fxed erythrocytes at the nanoscale were studied using the atomic- force microscope BioScope Resolve in PeakForce QNM mode in air.Results. The study has identifed an increase in the stiffness of the erythrocyte surface at a dose of 1 Gy and its decrease to almost control values at a dose of 100 Gy, which was accompanied by an increase in the size of the average cell of the erythrocyte membrane skeleton. At the same time, no signifcant changes in the morphology, adhesive properties and roughness of the relief of erythrocytes have been found.Conclusion. The obtained data indicate that X-ray radiation (1–100 Gy) induces the dose-depending reorganization of the structure and changes in the stiffness of the erythrocyte surface layer at the nanoscale without changing the cell morphology for rats on a high-cholesterol diet.