Enrichment of putative human epidermal stem cells based on cell size and collagen type IV adhesiveness

The enrichment and identification of human epidermal stem cells （EpSCs） are of paramount importance for both basic research and clinical application. Although several approaches for the enrichment of EpSCs have been established, enriching a pure population of viable EpSCs is still a challenging task. An improved approach is worth developing to enhance the purity and viability of EpSCs. Here we report that cell size combined with collagen type IV adhesiveness can be used in an improved approach to enrich pure and viable human EpSCs. We separated the rap- idly adherent keratinocytes into three populations that range in size from 5-7 μm （population A）, to 7-9 μm （population B）, to ≥9μm （population C） in diameter, and found that human putative EpSCs could be further enriched in population A with the smallest size. Among the three populations, population A displayed the highest density of plintegrin receptor, contained the highest percentage of cells in G0/G1 phase, showed the highest nucleus to cytoplasm ratio, and possessed the highest colony formation efficiency （CFE）. When injected into murine blastocysts, these cells participated in multi-tissue formation. More significantly, compared with a previous approach that sorted putative EpSCs according to pl-integrin antibody staining, the viability of the EpSCs enriched by the improved approach was significantly enhanced. Our results provide a putative strategy for the enrichment of human EpSCs, and encourage further study into the role of cell size in stem cell biology.

Errors Prediction for Vector-to-Raster Conversion Based on Map Load and Cell Size

Vector-to-raster conversion is a process accompanied with errors.The errors are classified into predicted errors before rasterization and actual errors after that.Accurate prediction of the errors is beneficial to developing reasonable rasterization technical schemes and to making products of high quality.Analyzing and establishing a quantitative relationship between the error and its affecting factors is the key to error prediction.In this study,land cover data of China at a scale of 1:250 000 were taken as an example for analyzing the relationship between rasterization errors and the density of arc length(DA),the density of polygon(DP) and the size of grid cells(SG).Significant correlations were found between the errors and DA,DP and SG.The correlation coefficient(R2) of a model established based on samples collected in a small region(Beijing) reaches 0.95,and the value of R2 is equal to 0.91 while the model was validated with samples from the whole nation.On the other hand,the R2 of a model established based on nationwide samples reaches 0.96,and R2 is equal to 0.91 while it was validated with the samples in Beijing.These models depict well the relationships between rasterization errors and their affecting factors(DA,DP and SG).The analyzing method established in this study can be applied to effectively predicting rasterization errors in other cases as well.

Organ-specific enhancement of metastasis by spontaneous ploidy duplication and cell size enlargement

Aneuploidy is commonly observed in breast cancer and is associated with poor prognosis. One frequent type of aneuploidy, hypertetraploidy, may derive from ploidy duplication of hyperdiploid cells. However, the pathological consequences of ploidy duplication in breast cancer progression have not been characterized. Here, we present an experimental system demonstrating spontaneous appearance of hypertetraploid cells from organ-specific metastatic variants of the MDA-MB-231 breast cancer cell line through ploidy duplication in vitro and in vivo. The hypertetraploid progenies showed increased metastatic potential to lung and brain, but not to bone, which may be partially explained by the distinct capillary structures in these organs that confer differential lodging advantages to tumor cells with enlarged size. Our results suggest a potential mechanistic link between ploidy duplication and enhancement of metastatic potentials, as was observed in previous clinical studies of breast cancer.

Industrial Preparation and Acid Resistance of Ultra-stable Y Zeolite with Small Cell Size Produced by Gas-phase Method

Small-cell HSY-S zeolite prepared by the gas-phase ultra-stable method had been researched and developed,and industrial preparation tests of HSY-S have been successfully carried out for the first time.The acid resistance of industrially prepared HSY-S was investigated by acid solutions with different pH values.The structures and properties of HSY-S and its acid-treated samples were characterized by XRD,XRF,BET,and IR.Results show that the HSY-S samples have the characteristics of high crystallinity,good stability,large specific surface area,and good acid resistance.

Relationship between Microcellular Foaming Injection Molding Process Parameters and Cell Size

In order to study the relationship between the main process parameters and the cell size, the mathematical model of cell growth of microcellular foaming injection process is built. Then numeric simulation is employed as experimental method, and the Taguchi method is used to analyze significance of effect of process parameters on the cell size. At last the process parameters are focused on melt temperature, injection time, mold temperature and pretidied volume. The significance order from big to small of the effect of each process parameters on cell size is melt temperature, pre-filled volume, injection time, and mold temperature. On the basis of above research, the effect of each process parameter on cell size is further researched. Appropriate reduction of the melt temperature and increase of the pre-filled volume can optimize the cell size effectively, while the effects of injection time and mold temperature on cell size are less significant.

Polylactic Acid (PLA) Foaming: Design of Experiments for Cell Size Control

In this study, a design of experiments (DoE) approach was used to develop a PLA open-cell foam morphology using the compression molding technique. The effect of three molding parameters (foaming time, mold opening temperature, and weight concentration of the ADA blowing agent) on the cellular structure was investigated. A regression equation relating the average cell size to the above three processing parameters was developed from the DoE and the analysis of variance (ANOVA) was used to find the best dimensional fitting parameters based on the experimental data. With the help of the DoE technique, we were able to develop various foam morphologies having different average cell size distribution levels, which is important in the development of open-cell PLA scaffolds for bone regeneration for which the control of cell morphology is crucial for osteoblasts proliferation. For example, at a constant ADA weight concentration of 5.95 wt%, we were able to develop a narrow average cell size distribution ranging between 275 and 300 μm by varying the mold opening temperature between 106°C and 112°C, while maintaining the foaming time constant at 8 min, or by varying the mold foaming time between 6 and 11 min and maintaining the mold opening temperature at 109°C.

Effects of cell size on compressive properties of aluminum foam

The effects of cell size on the quasi-static and dynamic compressive properties of open cell aluminum foams produced by infiltrating process were studied experimentally. The quasi-static and dynamic compressive tests were carried out on MTS 810 system and SHPB(split Hopkinson pressure bar) respectively. It is found that the elastic moduli and compressive strengths of the studied aluminum foam are not only dependent on the relative density but also dependent on the cell size of the foam under both quasi-static loading and dynamic loading. The foams studied show a significant strain rate sensitivity, the flow strength can be improved as much as 112%, and the cell size also has a sound influence on the strain rate sensitivity of the foams. The foams of middle cell size exhibit the highest elastic modulus, the highest flow strength and the most significant strain rate sensitivity.

Cell Size Dependent Responses of Phytoplankton Assemblages to Nitrate and Phosphate Additions in Surface Waters of the Northern South China Sea

Bioavailability of nitrogen (N) and phosphorus (P) is known to affect marine phytoplankton physiology, thus influencing their primary productivity;and it’s of general interest to see how the N or/and P additions affect the differently cell-sized phytoplankton assemblages. Data from the northern South China Sea showed that P addition increased up to 6 times of total chl a content within 24 h in the estuarine water;and N+P addition increased more than 20 times of chl a within 144 h in the pelagic water. The P addition powered 18.0% and 149% increase in the carbon fixation of larger (>3 μm) and smaller (

Cell Size versus Taxonomic Composition as Determinants of As (III &V) Sensitivity in the Estuarine Diatom Communities

Despite scarce studies have analyzed the relative growth inhibition of As (III) and As (V) to diatom, clear pattern of interspecies difference have been shown, identifying cell size as a key property determining the sensitivity of diatom to As. Evidence from cultures suggests that cell size is a key factor in determining the extent of arsenic (III) & (V) stress of diatom, with relatively lesser effects of As (V) than As (III) on small cells. Cent percent growth inhibition was observed for large size group (Coscinodiscus radiatus, Surirella, Amphipleura, Thalassiothrix, Cyclotella and Thalassiosira decipiens) relative to smaller size group (Skeletonema cf. costatum, Navicula rhombica, Amphora hyaline, Nitzschia longissima except Thalassisira. Interspecies differences in As tolerance by diatom in the mangrove ecosystem indicates cell size could be only one factor contributing to these differences. The results show that 81.7% of total arsenic was uptaken from culture media originally amended with arsenic. Looking to the extreme tolerance and arsenic removal efficiency, application of the species with smaller cell size relative to the other tested diatom for bioremediation purpose can be envisaged.

Comparison of Ground Water Bacterial Cell Sizes from the Agricultural, Domestic and Industrial Areas of Mysore District, Karnataka State, India

A two-year study on temporal variations in the ground water heterotrophic bacterial cell sizes of free living bacteria (FLB) and particle bound bacteria (PBB) from the agricultural, domestic and industrial areas was carried out from February 2005 to January 2007. The overall mean cell length of FLB and PBB was similar in all the ground water studied. However, the season wise grouped data revealed significant seasonal changes in cell length of FLB and PBB, as smaller bacteria were noticed during rainy season in the ground water in agricultural area in both the years, and only in the second year of study in domestic and industrial areas. Generally, it was noticed that there were summer maximum and rainy minimum values of the cell length of PBB in the ground water in agricultural, domestic and industrial areas in the second year of study. The Pearson's correlations showed the presence of 8 (in agricultural area), 5 (in domestic) and 3 (in industrial) significant correlations with environmental (Physico-chemical) parameters, respectively. The regression analysis revealed that as much as 12% of variation in the mean length of FLB was due to NO3 (+) in agricultural area and 9% due to total solids (+) in domestic area. However, the 8 % variation in bacterial cell size of FLB was due to Mg (+) in industrial area. Whereas, 13 % variation in mean length of PBB was due to SO4 (+) in agricultural area and 10% due to total anions of strong acid (TASA) (+) in domestic area. Furthermore, 10 % of variation was due to PO4 (+) in industrial area. Thus, the statistical analysis revealed that several environmental variables were potentially responsible for some of the temporal variations in aquatic heterotrophic bacterial cell size, suggesting probably the stressed environment in these ecosystems.

Sucrose-responsive osmoregulation of plant cell size by a long non-coding RNA

In plants,sugars are the key source of energy and metabolic building blocks.The systemic transport of sugars is essential for plant growth and morphogenesis.Plants evolved intricate molecular networks to effectively distribute sugars.The dynamic distribution of these osmotically active compounds is a handy tool for regulating cell turgor pressure,an instructive force in developmental biology.In this study,we have investigated the molecular mechanism behind the dual role of the receptor-like kinase CANAR.We functionally characterized a long non-coding RNA,CARMA,as a negative regulator of CANAR.Sugarresponsive CARMA specifically fine-tunes CANAR expression in the phloem,the route of sugar transport.Our genetic,molecular,microscopy,and biophysical data suggest that the CARMA–CANAR module controls the shoot-to-root phloem transport of sugars,allows cells to flexibly adapt to the external osmolality by appropriate water uptake,and thus adjust the size of vascular cell types during organ growth and development.Our study identifies a nexus of plant vascular tissue formation with cell internal pressure monitoring,revealing a novel functional aspect of long non-coding RNAs in developmental biology.

Effects of plug tray cell size on the growth of Atractylodes Chinensis (DC) Koidz seedlings

Atractylodes Chinensis(DC)Koidz is a perennial herb often used as a prescription medicine for influenza,to invigorate the spleen and remove dampness.The quality of the herb is determined by the quality of the seedlings.The traditional A.chinensis seedling production technique has nonuniform seedlings and low mechanisation.The plug seedling technique was used to produce A.Chinensis seedlings.This study was conducted to determine the growth characteristics of A.Chinensis seedlings according to the cell size of plug trays and number of days after sowing.Plant height,stem diameter,rhizome diameter,number of leaves,leaf area,and shoot dry and fresh weight of A.Chinensis seedlings were significantly higher in the P32-D treatment than in the P72,P50,and P32 treatments,but not significantly different from the P28-D treatment 60 d after sowing.The P28-D treatment resulted in a considerable drop in rhizome fresh weight and healthy seedling index,both of which are key indicators for assessing seedling quality.Although the differences in Pn among treatments were not significantly different,Tr was considerably greater in A.Chinensis seedlings treated with P32-D and P28-D than in the other three treatments.The P32-D and P28-D treatments had considerably greater potential maximum photochemical efficiency of PSII,quantum yield of photosystem II,photochemical quenching and electron transport rate than the other three treatments.Root vitality of A.Chinensis seedlings was significantly stronger in the P32-D treatment than in the other four treatments,and it was 1.9 times higher than in the P28-D treatment.The soluble protein,soluble sugar,and starch contents of A.Chinensis seedlings were highest in the P32-D treatment,but the differences among treatments were not significant.LUE,EUE,PY and EY were significantly higher in the P32-D treatment than in the other four treatments,being 1.3,1.3,1.4 and 1.4 times higher than in P28-D,respectively.On the other hand,as for the change in the growth of A.Chinensis seedlings according to the number of days after sowing,the growth of shoots and rhizome was most vigorous at the 60 d after sowing,while the fresh weight of the rhizome,which can be considered as an indicator of root growth,increased steadily during the experiment but slowed down after 60 d.As a result,32-cell deepened plug trays and a seedling nursery for a period of 60-75 d are recommended for commercial cultivation of A.Chinensis seedlings.This will provide technical support for production in A.Chinensis seedling.

Balanced biosynthesis and trigger threshold resulting in a double adder mechanism of cell size control

How cells accomplish cell size homeostasis is a fascinating topic, and several cell size regulation mechanisms were proposed: timer, sizer, and adder. Recently the adder model has received a great deal of attention. Adder property was also found in the DNA replication cycle. This paper aims to explain the adder phenomenon both in the division-centric picture and replication-centric picture at the molecular level. We established a self-replication model, and the system reached a steady state quickly based on evolution rules. We collected tens of thousands of cells in the same trajectory and calculated the Pearson correlation coefficient between biological variables to decide which regulatory mechanism was adopted by cells. Our simulation results confirmed the double-adder mechanism. Chromosome replication initiation and cell division control are independent and regulated by respective proteins.Cell size homeostasis originates from division control and has nothing to do with replication initiation control. At a slow growth rate, the deviation from adder toward sizer comes from a significant division protein degradation rate when division protein is auto-inhibited. Our results indicated the two necessary conditions in the double-adder mechanism: one is balanced biosynthesis, and the other is that there is a protein trigger threshold to inspire DNA replication initiation and cell division. Our results give insight to the regulatory mechanism of cell size and instructive to synthetic biology.

Epidermal Patterning Genes Impose Non‐cell Autonomous Cell Size Determination and have Additional Roles in Root Meristem Size Control

The regulation of cellular growth is of vital importance for embryonic and postembryonic patterning. Growth regulation in the epidermis has importance for organ growth rates in roots and shoots, proposing epidermal cells as an interesting model for cellular growth regulation. Here we assessed whether the root epidermis is a suitable model system to address cell size determination. In Arabidopsis thaliana L., root epidermal cells are regularly spaced in neighbouring tricho-（root hair） and atrichoblast （non-hair） cells, showing already distinct cell size regulation in the root meristem. We determined cell sizes in the root meristem and at the onset of cellular elongation, revealing that not only division rates but also cellular shape is distinct in tricho-and atrichoblasts. Intriguingly, epidermal-patterning mutants, failing to define differential vacuolization in neighbouring epidermal cell files, also display non-differential growth. Using these epidermal-patterning mutants, we show that polarized growth behaviour of epidermal tricho-and atrichoblast is interdependent, suggesting non-cell autonomous signals to integrate tissue expansion. Besides the interweaved cell-type-dependent growth mechanism, we reveal an additional role for epidermal patterning genes in root meristem size and organ growth regulation. We conclude that epidermal cells represent a suitable model system to study cell size determination and interdependent tissue growth.

Fruit size control by a zinc finger protein regulating pericarp cell size in tomato

Fruit size is largely defined by the number and size of cells in the fruit.Endoreduplication–a specialized cell cycle–is highly associated with cell expansion during tomato fruit growth.However,how endoreduplication coupled with cell size is regulated remains poorly understood.In this study,we identified a zinc finger gene SlPZF1(Solanum lycopersicum PERICARP-ASSOCIATED ZINC FINGER PROTEIN 1)that was highly expressed in the pericarp of developing fruits.Plants with altered SlPZF1 expression produced smaller fruits due to the reduction in cell size associated with weakened endoreduplication.Overexpressing SlPZF1 delayed cell division phase by enhancing early expression of several key cell cycle regulators including SlCYCD3;1 and two plant specific mitotic cyclin-dependent protein kinase(SlCDKB1 and SlCDKB2)in the pericarp tissue.Furthermore,we identified 14 putative SlPZF1 interacting proteins(PZFIs)via yeast two hybrid screening.Several PZFIs,including Pre-mRNA-splicing factor(SlSMP1/PZFI4),PAPA-1-like conserved region family protein(PZFI6),Fanconi anemia complex components(PZFI3 and PZFI10)and bHLH transcription factor LONESOME HIGHWAY(SILHW/PZFI14),are putatively involved in cell cycle regulation.Our results demonstrate that fruit growth in tomato requires balanced expression of the novel cell size regulator SlPZF1.

Study on cell size variation in overdriven gaseous detonations

The cell size variation in overdriven gaseous detonations is studied in hydrogen/oxygen and acetylene/oxygen mixtures.The local self-similarity of Mach reflection of detonations on the wedge in the far field renders the presence of a steady overdriven Mach stem to be possible.The study focuses on the cell size change of overdriven Mach stem on the wedge surface other than on the sidewall.The detonation cell pattern on the wedge surface has a complicated process of three-stage pattern,i.e.,the cells decreasing from large to small size,and then increasing asymptotically to a medium size and keeping constant.The cell size ratio with increasing the degree of overdrive is also examined.It is found that the ratio decays as the degree of overdrive increases.However,as the wedge angle increases to a critical value,finer cells are not created on the smoke foils.Ng’s model used to predict the cell size is also found to be valid only for detonations with relative large instability parameters,but presents large errors for highly overdriven detonations with low instability.A modification to Ng’s model is proposed based on the experimental results.

Effects of developmental plasticity on heat tolerance may be mediated by changes in cell size in Drosophila melanogaster

There is a growing interest in the physiology underpinning heat tolerance of ectotherms and their responses to the ongoing rise in temperature.However,there is no consensus about the underlying physiological mechanisms.According to''the maintain aerobic scope and regulate oxygen supply^hypothesis,responses to warming at different organizational levels contribute to the ability to safeguard energy metabolism via aerobic pathways.At the cellular level,a decrease in cell size increases the capacity for the uptake of resources(e.g.,food and oxygen),but the maintenance of electrochemical gradients across cellular membranes implies greater energetic costs in small cells.In this study,we investigated how different rearing temperatures atTected cell size and heat tolerance in the fruit fly Drosophila melanogaster.We tested the hypothesis that smallcr-celled flies are more tolerant to acute,intense heat stress whereas larger-celled flies are more tolerant to chronic,mild heat stress.We used the thermal tolerance landscape framework,which incorporates the intensity and duration of thermal challenge.Rearing temperatures strongly affected both cell size and survival times.We found different effects of developmental plasticity on tolerance to either chronic or acute heat stress.Warm-reared flies had both smaller cells and exhibited higher survival times under acute,intense heat stress when compared to cold-reared flies.However,under chronic,mild heat stress,the situation was reversed and cold-reared flies,consisting of larger cells,showed better survival.These differences in heat tolerance could have resulted from direct effects of rearing temperature or they may be mediated by the correlated changes in cell size.Notably,our results are consistent with the idea that a smaller cell size may confer tolerance to acute temperatures via enhanced oxygen supply,while a larger cell may confer greater tolerance to chronic and less intense heat stress via more efTicient use of resources.

Wide grain 4,encoding an alpha-tubulin,regulates grain size by affecting cell expansion in rice

Rice is one of the three most important food crops in the world.Increasing rice yield is an effective way to ensure food security.Grain size is a key factor affecting rice yield;however,the genetic and molecular mechanisms regulating grain size have not been fully investigated.In this study,we identified a rice mutant,wide grain 4-D(wg4-D),that exhibited a significant increase in grain width and a decrease in grain length.Histological analysis demonstrated that WG4 affects cell expansion thereby regulating grain size.MutMap-based gene mapping and complementary transgenic experiments revealed that WG4 encodes an alpha-tubulin,OsTubA1.A SNP mutation in WG4 affected the arrangement of cortical microtubules and caused a wide-grain phenotype.WG4 is located in nuclei and cytoplasm and expressed in various tissues.Our results provide insights into the function of tubulin in rice and identifies novel targets the regulation of grain size in crop breeding.

Cell size: a key determinant of meristematic potential in plant protoplasts

Metabolic pathway reconstruction and gene edits for native natural product synthesis in single plant cells are considered to be less complicated when compared to the production of non-native metabolites.Being an efficient eukaryotic system,plants encompass suitable post-translational modifications.However,slow cell division rate and heterogeneous nature is an impediment for consistent product retrieval from plant cells.Plant cell synchrony can be attained in cultures developed in vitro.Isolated plant protoplasts capable of division,can potentially enhance the unimpaired yield of target bioactives,similar to microbes and unicellular eukaryotes.Evidence from yeast experiments suggests that‘critical cell size’and division rates for enhancement machinery,primarily depend on culture conditions and nutrient availability.The cell size control mechanisms in Arabidopsis shoot apical meristem is analogous to yeast notably,fission yeast.If protoplasts isolated from plants are subjected to cell size studies and cell cycle progression in culture,it will answer the underlying molecular mechanisms such as,unicellular to multicellular transition states,longevity,senescence,‘cell-size resetting’during organogenesis,and adaptation to external cues.

Observation of Cell-Size Variation under Environmental Stress by Fluorescence Correlation Spectroscopy without Objective Image Magnification

Fluorescence correlation spectroscopy （FCS） without objective image magnification （without using con-focal microscope） was applied to observe the variation in cell size of Escherichia coli （E. coli） induced by the anti-cancer agent MitomycinC （MMC）. In the system without image magnification followed in this study, the suspension of E. coli cells was stirred, and the difference in movement due to the different cell sizes induced by the compulsive solution flow was detected. The addition of 0.1-0.4 pg/L of MMC elongated the E. coli cell length from about 3.6 to 7.8μm. The flow cell （i.d. = about 1 mm） also produced a size-dependent correlation curve, The present system is not based on single molecular FCS but is inexpensive and effective at observing the variation in cell size induced by environmental changes.