Decrease In Average Cell Size Research Articles

Exposure to High Dosage of Gold Nanoparticles Accelerates Growth Rate by Modulating Ribosomal Protein Expression.

Gold nanoparticles (AuNPs) have been utilized in various biomedical applications including diagnostics and drug delivery. However, the cellular and metabolic responses of cells to these particles remain poorly characterized. In this study, we used bacteria (Escherichia coli and Bacillus subtilis) and a fungus (Saccharomyces cerevisiae) as model organisms to investigate the cellular and metabolic effects of exposure to different concentrations of citrate-capped spherical AuNPs with diameters of 5 and 10 nm. In different growth media, the synthesized AuNPs displayed stability and microorganisms exhibited uniform levels of uptake. Exposure to a high concentration of AuNPs (1012 particles) resulted in a reduced cell division time and a 2-fold increase in cell density in both bacteria and fungus. The exposed cells exhibited a decrease in average cell size and an increase in the expression of FtsZ protein (cell division marker), further supporting an accelerated growth rate. Notably, exposure to such a high concentration of AuNPs did not induce DNA damage, envelope stress, or a general stress response in bacteria. Differential whole proteome analysis revealed modulation of ribosomal protein expression upon exposure to AuNPs in both E. coli and S.cerevisiae. Interestingly, the accelerated growth observed upon exposure to AuNPs was sensitive to sub-minimum inhibitory concentration (sub-MIC) concentration of drugs that specifically target ribosome assembly and recycling. Based upon these findings, we hypothesize that exposure to high concentrations of AuNPs induces stress on the translation machinery. This leads to an increase in the protein synthesis rate by modulating ribosome assembly, which results in the rapid proliferation of cells.

Enhancing interfacial interaction of immiscible PCL/PLA blends by in-situ crosslinking to improve the foamability

The immiscible between poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) significantly hinders the properties and application of the blends. In this work, the use of benzoyl peroxide (BPO) is an effective methods to improve the compatibility and foamability of immiscible PCL/PLA blends. The tensile test results showed a 41% increase in yield tensile strength and a 632% increase in elongation at break of the crosslinked PCL/PLA/0.6%BPO film compared to the pristine PCL/PLA blends, which demonstrate the enhancement of PCL/PLA interfacial interaction. The melt strength of the blends was gradually increased due to the improvement of interfacial interaction, which led to the decrease of average cell size and the increase of cell density of the PCL/PLA foam. Moreover, the open-cell structure was altered to a highly close-cell structure with increasing BPO content. Consequently, structural-tunable foams can be obtained by varying degrees of interfacial interaction.

Tuning of renewable sponge‐like polyurethane physical‐chemical and morphological properties using the pullulan as a reactive filler

AbstractThis study aimed to evaluate the effect of pullulan (Pull) on a renewable polyurethane sponge‐like scaffold synthesized from the Pull mixture with the castor oil‐based polyol and the prepolymer using the situ foaming method. The Pull contents on the sponge‐like are 5, 10, and 20 wt.%. The samples were evaluated by optical microscopy (OM), scanning electron microscopy (SEM), density, Fourier transform infrared spectroscopy (FTIR), contact angle, Thermogravimetry, X‐ray diffraction analysis (XRD), and compression strength test, respectively. FTIR results indicated that Pull was hydrogen‐bonded to PU foam chains and increased the sponge‐like scaffolds density, inducing a decrease in average cell size compared to the pristine PU, confirming that they act as nucleating agents. The Pull addition improved PU foams' hydrophobicity and mechanical properties and caused a thermal stability median between Pull and pristine PU. Thus, all renewable sponge‐like scaffolds were hydrophobics and presented appropriate mechanical behavior, exhibiting better physicochemical properties, and appearing as promising candidates for biomedical applications.

Effect of Zr on magnetic properties and electrical resistivity of Sm(CobalFe0.09Cu0.09Zrx)7.68 magnets

In this work, the effect of Zr content on magnetic properties and electrical resistivity of Sm(CobalFe0.09Cu0.09Zrx)7.68 (x = 0.020, 0.025, 0.030, 0.035) high temperature magnets has been investigated. More Zr content results in the decrease of average cell size and the increase of the density of lamellar structure. In addition, a large number of phase boundaries between lamellar phase and cellular structure have also been formed. The intrinsic coercivity of 550 °C enhances from 3.21 kOe to 6.05 kOe with the increase of Zr content. Furthermore, electrical resistivity shows obviously different variation in different directions with increasing Zr content. At room temperature and 127 °C, the electrical resistivity improves from 68.2 μΩ cm to 91.7 μΩ cm and from 87.1 μΩ cm to 103.3 μΩ cm with increasing x from 0.020 to 0.035 in the direction parallel to c-axis, respectively. However, there is only a slight increase in the electrical resistivity in the direction perpendicular to c-axis. The rise of electrical resistivity in different directions has been discussed. Research results indicate that increasing the density of the lamellar phase is an effective way to increase electrical resistivity in the 2:17-type Sm-Co magnets.

Microcellular chlorinated polyethylene (CM) rubber foam by using N2 as blowing agent

Microcellular Chlorinated Polyethylene (CM) foams were prepared through the batch-foaming method by using nitrogen as blowing agent. The effects of varying curing time, curing temperature, crosslinking agent content, carbon black content on the cell structure and physical-mechanical properties of CM foam were investigated by scanning electron microscopy (SEM) and universal testing machine (UTM) respectively. The effect of the crosslink density on the CM foaming by varying curing time, curing temperature and crosslink agent revealed that there must be a minimum crosslink density attained in the vulcanizates for its effective foaming. However, when increasing the crosslink density of the vulvanizates beyond the sufficient crosslink density needed for foaming, the average cell sizes of the foams decreased and cell density increased. Expansion of the foams reduce its mechanical properties whereas increase of crosslink density of the matrix improved the mechanical properties. The existence of carbon black caused a decrease in average cell size and increase in cell density for the CM foams, resulting significant increase in mechanical properties of CM foams with increase of carbon black content. The observed phenomenon is attributed with good reinforcing behavior of carbon black to the CM foams.

Wind drives microbial eukaryote communities in a temperate closed lagoon

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 78:187-200 (2017) - DOI: https://doi.org/10.3354/ame01814 Wind drives microbial eukaryote communities in a temperate closed lagoon Bérangère Péquin1, Vani Mohit1, Timothée Poisot2, Réjean Tremblay3, Connie Lovejoy1,* 1Département de Biologie, Québec-Océan, Institut de Biologie Intégrative et des Systèmes (IBIS), 1045 avenue de la Médecine, Université Laval, Québec G1V 0A6, Canada 2Québec Centre for Biodiversity Sciences and Département de Sciences Biologiques Université de Montréal, 90 Avenue Vincent d’Indy, Montréal, Québec H2V 2S9, Canada 3Institut des Sciences de la Mer (ISMER), Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec G5L 3A1, Canada *Corresponding author: connie.lovejoy@bio.ulaval.ca ABSTRACT: Phylogenetically diverse pico- (cells <2 µm diameter) and nanoplanktonic (2–20 µm) microbial eukaryotes are ubiquitous in coastal ecosystems; however, there is little understanding of the intrinsic (biological) and extrinsic (abiotic) factors that influence species composition in these communities. We investigated the microbial eukaryotes in the Havre-aux-Maisons Lagoon (Magdalen Islands, Gulf of St. Lawrence), which lacks riverine inputs and has little exchange with the surrounding gulf. We hypothesized that intrinsic successional processes and nutrient drawdown in the lagoon would lead to a decrease in average cell size over the summer. Samples for nutrients, cell concentrations from flow cytometry (FCM), and taxonomic identity using high throughput amplicon sequencing of the V4 region of the 18S rRNA gene were collected on 10 occasions between June and October 2009 and analysed in the context of physical and climatological data. Ratios of pico- to nanophytoplankton indicated no decline in average cell size over the summer, with picophytoplankton concentrations more variable. The microbial eukaryotic communities formed 3 major clusters based on phylogeny and UniFrac analysis. Taxonomically, dinoflagellates were dominant in the largest cluster, while picophytoplankton and nanoflagellates dominated the 2 other clusters. The concentrations of eukaryotic picophytoplankton increased in early summer, but decreased following periods with lower average wind speeds and increased following higher average winds. During periods with lower average wind speeds, dinoflagellates dominated. The clear impact of wind was consistent with climatological events indirectly influencing biotic interactions and picophytoplankton species composition. KEY WORDS: Dinoflagellates · Coastal processes · Microbial community selection · 18S rRNA gene Full text in pdf format Supplementary material PreviousCite this article as: Péquin B, Mohit V, Poisot T, Tremblay R, Lovejoy C (2017) Wind drives microbial eukaryote communities in a temperate closed lagoon. Aquat Microb Ecol 78:187-200. https://doi.org/10.3354/ame01814 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 78, No. 3. Online publication date: March 10, 2017 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2017 Inter-Research.

Exfoliative cytology: A possible tool in age estimation in forensic odontology.

Introduction:Age determination of unknown human bodies is important in the setting of a crime investigation or a mass disaster because the age at death, birth date, and year of death as well as gender can guide investigators to the correct identity among a large number of possible matches.Objective:The study was undertaken with an aim to estimate the age of an individual from their buccal smears by comparing the average cell size using image analysis morphometric software.Materials and Methods:Buccal smears were collected from 100 apparently healthy individuals. After fixation in 95% alcohol, the smears were stained using standard Papanicolaou laboratory procedure. The average cell size was measured using Dewinter's image analysis software version 4.3. Statistical analysis of the data was done using one-way ANOVA, Bonferroni procedures.Results:The results showed significant decrease in average cell size of individual with increase in age. The difference was highly significant in age group of above 60 years.Conclusion:Age-related alterations are observed in buccal smears.

Influence of modified starches on properties of gluten-free dough and bread. Part II: Quality and staling of gluten-free bread

The aim of the study was to check the quality of gluten-free bread produced basing on the recipes, in which part of native starch was replaced with high amylose corn starch (HACS), acetylated distarch adipate (ADA), and hydroxypropyl distarch phosphate (HDP). The application 10 or 15% of chemically modified starches (HDP, ADA) caused the increase in volume of the obtained gluten-free loaves. The changes were accompanied by a decrease of average cell size, and an increase in their number. Due to the addition of modified starch crumb structure became more elastic, which was revealed in the results of stress relaxation. A slight decrease in hardness and chewiness of the crumb was also observed on the day of baking, and its extent depended on the level of modified starch, and was a little more pronounced in case of starch adipate. In comparison to the chemically modified starches, HACS deteriorated structural and mechanical properties of the crumb, which is probably related to their resistance to pasting and divergence in retrogradation pattern, where amylose component is more important than amylopectin.

Injection Molded Solid and Microcellular Polylactide Compounded with Recycled Paper Shopping Bag Fibers

Abstract Recycled paper shopping bag fibers were melt-compounded using a batch mixer with biobased/biodegradable polylactide (PLA) at 10 and 30 wt.% using silane as a coupling agent. These PLA/fiber composites were then injection molded to produce both solid and microcellular tensile bars. The mechanical properties (specific modulus, specific tensile strength, specific toughness, and strain at break) of the neat PLA and PLA composites were tested and the cell morphology of the microcellular samples was examined using scanning electron microscopy. It was observed that the addition of the recycled paper shopping bag fibers resulted in an increase in cell density and decrease in average cell size for the microcellular components when compared with the neat PLA. The addition of the fibers increased the specific modulus of both solid and microcellular components, and high fiber contents (30 wt.%) resulted in an increase in specific tensile strength, yet yielded a decrease in the strain at break and specific toughness. The storage modulus was also improved with the addition of 10 and 30 wt.% fibers for both solid and microcellular components.

Consequences of pelagic food‐web changes during a long‐term lake oligotrophication process

Changes in the pelagic communities of Lago Maggiore (Italy) during 1983–1995, when the lake underwent a process of oligotrophication caused by a gradual phosphorus abatement, were analyzed. Events in the plankton after a large increase of Bythotrephes longimunus starting in 1988 were strikingly similar to those in Lake Michigan after the initial Bythotrephes cederstroemii invasion. They included a decrease in numbers of Daphnia, assumed to be caused by Bythotrephes predation, and an increase in the body size of Daphnia. In Lago Maggiore, these changes took place with a stable fish stock. As Lehman initially found in Lake Michigan, herbivory did not constrain the maximum phytoplankton biomass. However, a significant negative correlation (P &lt; 0.01) existed between Daphnia and phytoplankton cell numbers over the whole long−term period. It is concluded that, although chlorophyll and biovolume changes are dependent on phosphorus reduction, the observed increase in cell numbers of phytoplankton and the decrease in average cell size may depend not only on phosphorus decline but also web during lake oligotrophication.

Kinetics of chicken embryonic thymocyte development in ovo and in organ culture.

Thymocyte development was monitored in an embryonic thymus organ culture system to establish a model in the chicken in which the functional nature of the thymic microenvironment could be assessed. Thymus lobes were removed from 10-day-old embryos and cultured for 2-10 days. Cell yield increased to a maximum in 4-8 days of culture with a corresponding decrease in average cell size. An initial thymocyte population of predominantly CD3-CD4-CD8- cells gave rise to all CD3/CD4/CD8-defined subpopulations in vitro, maintaining high levels of CD3-CD4-CD8+ and CD3+CD4-CD8+ cells and a low representation of CD3-CD4+CD8-, CD3+CD4+CD8-, CD3-CD4+CD8+ and CD3+CD4+CD8+ thymocytes. This is the first observation of a CD3-CD4+CD8- population in the chicken. Developmental kinetics of CD3+ cells were similar to that in the embryo, suggesting that the in vitro environment is sufficient to promote and maintain thymocyte maturation. Thymocytes of both the gamma delta and alpha beta T cell receptor (TcR) lineages developed in that order, confirming in ovo data and the lineage potential of the first wave of thymocyte precursors. One unusual finding was a relative accumulation of gamma delta TcR+ thymocytes in culture, incorporating all CD4/CD8 subsets, including a previously undetected population, CD4+CD8-. This may indicate a favorable developmental environment or simply a lack of normal cellular emigration. A detailed comparison with T cell development in the embryo demonstrated that the chicken thymus organ culture system reflects thymic events in ovo during a limited time period and thus should prove useful in the identification of functionally relevant thymic molecules.