Electrical determination of viability in saline-treated mouse myeloma cells.

Suspension of mouse myeloma cells in phosphate buffered saline (PBS) induced a significant amount of cell death. The lethal effects of PBS include an increase in cell lysis, a decreased ability of cells to exclude trypan blue, and a decrease in the colony-forming ability of these cells. Dead cells were also detected on a Coulter counter by the increase in the fraction of cells with a smaller electrical size distribution (ESD). Comparing mixtures of live and dead cells by ESD and trypan-blue exclusion showed a high correlation of electrical size with viability (correlation coefficient = 0.98). Sizing of PBS-treated cells by light microscopy suggested that the altered ESD of the PBS-treated cells was due to a downward shift in the volume distribution. Light-scattering experiments also suggested a decrease in the size of cells after PBS treatment. An increase in permeability of the cell membrane may also contribute to these results. We conclude that electrical sizing is an excellent indicator of physical changes that result from PBS-induced cell death, and is an effective method for distinguishing live and dead mouse myeloma cells after PBS treatment.     

Countercurrent distribution of L line monolayer and suspension cell cultures in a 2-phase polymer system

The distribution of two sulines of L cells, differing in adhesive properties (monolayer and suspension cultures), have been investigated using polymer two-phase system dextran-500-polyenthylenglycol-600. By counter-current distribution it has been shown that most of the cells growing in monolayer have low coefficients of partition, unlike cells grown in suspension having a high coefficient of partition. It is supposed that differences revealed in properties of the cell surface may be associated with the ability of cells to form adhesive contacts.     

Countercurrent distribution in a 2-phase polymer system of cultured cells following their exposure to trypsin, versen, dimethyl sulfoxide and suboptimal temperature

A study was made of the effects of trypsin (0.25%) EDTA (0.02%), DMSO (10%) and suboptimal temperatures (16-18 degrees C) on the line L cells of monolayer and suspension cultures by the method of counter-current distribution in two-phase polymer system Dextran-500/poly (ethylene) glycol-6000. It has been shown that these agents cause the increase in number of cells with low partition coefficient, which is most expressed in the population of monolayer subline cells.     

Cell-cell affinity probed by countercurrent distribution in two-polymer aqueous phase systems

Aqueous solutions of dextran and of polyethylene glycol when mixed form immiscible liquid two-phase systems with a polyethylene glycol-rich top and a dextran-rich bottom. Such phases can be buffered and rendered isotonic and are suitable for the partition of cells. The partition coefficient of cells (i.e., their relative affinity for the top or bottom phase or their adsorption at the interface) depends on the polymer concentrations, on the ionic composition and concentration and, most sensitively, on their membrane surface properties. When two cell populations are mixed the partition coefficient of each is unaffected by the presence of the other population unless an interaction takes place between them. By countercurrent distribution of two cell populations, in a phase system selected such that the partition coefficient of one population is high (i.e., more cells in the top phase) and of the other low, one should be able to detect subtle interactions between cells in the two populations should they occur. Results of experiments with a model system consisting of human peripheral blood mononuclear cells and sheep red blood cells bear out the feasibility of this approach. At low ratios of sheep erythrocytes to mononuclear cells no interaction is apparent. With increasing ratios there is an increasing shift in the distribution curve of subpopulations of mononuclear cells (i.e., T-lymphocytes) as they interact with the sheep red cells. Substitution of rabbit red cells for sheep erythrocytes (at high ratios) reveals a small yet significant shift of a subpopulation of mononuclear cells as well. Distribution of human peripheral blood lymphocytes from patients with chronic lymphocytic leukemia (all B-lymphocytes) are essentially unaffected by the presence of sheep red cells. This sensitive new method, still in its infancy, holds out the hope for the detection of previously unknown cell-cell affinities and for probing suspected cell-cell interactions.     

Methanotrophic Bacteria and Facilitated Transport of Pollutants in Aquifer Material

In situ stimulation of methanotrophic bacteria has been considered as a methodology for aquifer remediation. Chlorinated aliphatic hydrocarbons such as trichloroethylene are fortuitously oxidized by the methane monooxygenase produced by methanotrophic bacteria. Experimental results are presented that indicate that both colloidal suspensions containing methanotrophic cells and the soluble extracellular polymers produced by methanotrophic cells have the potential to enhance the transport and removal of other environmental contaminants such as polynuclear aromatic hydrocarbons and transition metals in aquifer material. Three well-characterized methanotrophic bacteria were used in the experiments: Methylomonas albus BG8 (a type I methanotroph), Methylosinus trichosporium OB3b (a type II methanotroph), and Methylocystis parvus OBBP (a type II methanotroph). Isotherms were obtained for sorption of two radiolabeled pollutants, [¹⁴C] phenanthrene and ¹⁰⁹Cd, onto an aquifer sand in the presence and absence of washed cells and their extracellular polymer. Column transport experiments were performed with the washed methanotrophic cells and phenanthrene. The distribution coefficients for Cd with extracellular polymers were of the same order as that obtained with the aquifer sand, indicating that polymers from the methanotrophic bacteria could act to increase the transport of Cd in a porous medium. Polymer from BG8 significantly reduced the apparent distribution coefficient for Cd with an aquifer sand. [¹⁴C] phenanthrene also sorbed to extracellular polymer and to washed, suspended methanotrophic cells. The exopolymer of BG8 and OBBP significantly reduced the apparent distribution coefficient (K_d) for phenanthrene with aquifer sand. The distribution coefficients for phenanthrene with the methanotrophic cells were an order of magnitude greater than those previously reported for other heterotrophic bacteria. Cells of the methanotrophs also significantly reduced the apparent K_d for phenanthrene with an aquifer sand. The three strains of methanotrophs tested displayed mobility in a column of packed sand, and strain OBBP reduced the retardation coefficient of phenanthrene with an aquifer sand by 27%. These data indicate that both extracellular polymer and mobile cells of methanotrophic bacteria display a capacity to facilitate the mobility of pollutant metals and polynuclear aromatic hydrocarbons in aquifer material.     

Flow cytometric analyses of intraplant nuclear DNA content variation induced by sticky chromosomes

BACKGROUND: In several plant species, sticky chromosomes are a consequence of genetic mutations or environmental effects on mitosis and meiosis. Sticky chromosomes result in an unequal distribution of genetic material in daughter cells. This unequal distribution is hypothesized to result in an increase in the coefficient of variation (CV) of the G1 peak of dividing cells. METHODS: The st1 mutant and a nonmutant line in the same genetic background of maize (Zea mays L.) were planted in a soilless mix. A wheat (Triticum aestivum L. em thell.) line was grown in both low and high aluminum-saturated soil. Both plant species were assessed for sticky chromosomes by Feulgen-stained mitotic analysis and flow cytometric analysis of propidium iodide (PI)-stained G1 nuclei. RESULTS: In the st1 mutant, a significant increase in the number of abnormal anaphase figures was observed. An increase in abnormal mitotic figures was observed in wheat plants grown in aluminum soil. Using flow cytometry, an increase in the CV of the G1/G0 peak was seen in the maize mutant and in wheat grown at high levels of aluminum saturation. This increase correlated with the number of abnormal anaphase cells observed. CONCLUSIONS: Flow cytometry was sensitive enough to detect the intraplant nuclear DNA variation associated with sticky chromosomes within a plant.     

Transferrin binding capacity as a marker of differentiation and maturation of rat erythroid cells fractionated by counter current distribution in aqueous polymer two-phase systems

Rat bone marrow cell populations, containing different proportions of erythroid cells, have been fractionated by counter-current distribution in the non-charge-sensitive dextran/polyethyleneglycol two-phase systems on the basis of hydrophobic cell surface properties. Cell fractions with a low distribution coefficient, which contain non-erythroid cells and early erythoblasts, showed a low transferrin binding capacity and a low haemoglobin/cell ratio whereas cell fractions with a high distribution coefficient, which contain intermediate-late erythroblasts and mature red cells, showed an elevated transferrin binding capacity and the highest haemoglobin/cell ratio. These results support transferrin binding capacity as a good marker parameter for the erythroid bone marrow cell differentiation and maturation processes.     

黑龙江省汤旺河和呼兰河流域森林对河川年径流量的影响

利用连续１７年的流域森林资源和水文资料,分析黑龙江省汤旺河和呼兰河流域森林对河川径流的调节效应,结果表明：（１）森林能使径流年内分配和年际变化趋于均匀,其调节径流能力与森林状况相关;（２）森林覆被率和单位面积蓄积与河川年径流量和年径流系数均呈正相关关系,森林具有增加年径流量和年径流系数的作用,但年径流量和年径流系数主要受年降雨量的影响。     

The effect of neuraminidase on the relative surface charge-associated properties of rat red blood cells of different ages

Approx. 70% of the sialic acid on the rat erythrocyte surface is susceptible to cleavage by neuraminidase (Vibrio cholerae). Neuraminidase treatment results in a reduction in the partition coefficient (K) of the red cells in a charged dextran-poly(ethylene glycol) aqueous phase system and in the electrophoretic mobility of the cells. Countercurrent distribution of rat neuraminidase-treated erythrocytes, containing 59Fe-labeled mature red cells of distinct age, indicates that (a) the electrophoretic mobilities of red cells in different cavities along the extraction train increase with increasing K, as is the case with untreated erythrocytes, and (b) the cell age-related differences in surface charge-associated properties are neither eliminated nor altered by the enzyme action.     

Variability of the duration of the cell cycle in pig embryo kidney cells in monolayer culture and correlation of the cycle duration in sister cells

The distribution of generation time of sister cells for the exponentially proliferating monolayer SPEV culture was obtained with time lapse cinemicrographic technique. The distribution is characterized by the average generation time equal to 24.3 hour, with the variation coefficient, asymmetry coefficient and correlation coefficient for sister pair cell being, respectively, 17%, 0.2 and 0.78. The results obtained are compared with the prediction of "a random transition" in the cell cycle.     

The discrete-time kinetic model analysis of DNA content distributions in experimental tumour cells.

A method was developed to analyse and characterize FMF measurements of DNA content distribution, utilizing the discrete time kinetic (DTK) model for cell kinetics analysis. The DTK model determines the time sequence of the cell age distribution during the proliferation of a tumor cell population and simulates the distribution pattern of the DNA content of cells in each age compartment of the cell cycle. The cells in one age compartment are distributed and spread into several compartments of the DNA content distribution to allow for different rates of DNA synthesis and instrument dispersion effects. It is assumed that the DNA content of cells in each age compartment has a Gaussian distribution. Thus, for a given cell age distribution the DNA content distribution depends on two parameters of the cells in each age compartment: the average DNA content and its coefficient of variation. As the DTK model generates the best fit DNA content distribution to the FMF measurement data, it enables one to estimate specific values of these two parameters in each stage of the cell cycle and to determine the fraction of cells in each cycle phase. The method was utilized to fit FMf measurements of DNA content distributions and to analyse their relationship tothe cell kinetic parameters, namely cell loss rate, cell cycle times and grwoth graction of exponentially growing Chinese hamster ovary cells in vitro and, also, with a wide range of coeffficients of variation, of the L1210 ascites tumour during the growth period.     

THE DISCRETE–TIME KINETIC MODEL ANALYSIS OF DNA CONTENT DISTRIBUTIONS IN EXPERIMENTAL TUMOUR CELLS

A method was developed to analyse and characterize FMF measurements of DNA content distribution, utilizing the discrete time kinetic (DTK) model for cell kinetics analysis. The DTK model determines the time sequence of the cell age distribution during the proliferation of a tumor cell population and simulates the distribution pattern of the DNA content of cells in each age compartment of the cell cycle. The cells in one age compartment are distributed and spread into several compartments of the DNA content distribution to allow for different rates of DNA synthesis and instrument dispersion effects. It is assumed that the DNA content of cells in each age compartment has a Gaussian distribution. Thus, for a given cell age distribution the DNA content distribution depends on two parameters of the cells in each age compartment: the average DNA content and its coefficient of variation. As the DTK model generates the best fit DNA content distribution to the FMF measurement data, it enables one to estimate specific values of these two parameters in each stage of the cell cycle and to determine the fraction of cells in each cycle phase. The method was utilized to fit FMF measurements of DNA content distributions and to analyse their relationship to the cell kinetic parameters, namely cell loss rate, cell cycle times and growth fraction of exponentially growing Chinese hamster ovary cells in vitro and, also, with a wide range of coefficients of variation, of the L1210 ascites tumour during the growth period.     

Enzymes in the process of neuronal differentiation of the hen spinal ganglion, spinal cord and tectum opticum. A cytophotometric histochemical study

Changes in the activity of 13 enzymes are described in the process of cytodifferentiation of the nerve cells of spinal ganglion, the motor neurons of spinal cord and large nerve cells of the III layer of tectum opticum in 7, 10 and 21 day old chick embryos. Cytophotometry was performed with MZFV-1 (LOMO) by means of plug-method. A relatively high activity of glucose-6-phosphat dehydrogenase, diaphorase, alpha-glycerophosphate dehydrogenase and, partially, acetylcholine esterase was found already in the 7 days old embryo. The activity of monoamine oxidase, aldolase-glyceroaldehyde phosphate dehydrogenase, isocitrate dehydrogenase, glutamate dehydrogenase increased markedly on the 21st day. When studying the reciprocal distribution of two enzymes in separate cells, pairs of enzymes with a high value of correlation coefficient were found. The cytodifferentiation was found to be accompanied by changes in the coefficient of correlation of the same pair of enzymes.     

Possible role of genetic factor(s) on age-related increase of peripheral CD4+CD8+ double positive T cells in cynomolgus monkeys.

Mature TCR alpha beta T cells in peripheral blood are generally classified into either CD4 single positive (sp) T cells or CD8sp T cells. Several studies demonstrated that considerable amounts of CD4+CD8+ double positive (DP) T cells exist in peripheral blood of human and several animals. In particular, we previously reported that peripheral DP T cells increase in an age-related manner in cynomolgus monkeys (Macaca fascicularis), but the finding that DP T cells in some aged monkeys were maintained at a low proportion (under 5%), suggests that the increase in peripheral DP T cells might be genetically controlled in cynomolgus monkeys. To test this hypothesis, 24 families were randomly selected and used in a formal genetic analysis of the proportion of DP T cells. Parents and offspring in selected families were classified into DP-High and DP-Low groups based on a 5% cutoff level of DP T cells. The cutoff value was set by analysis of the distribution of the proportion of DP T cells. Nine out of 13 offspring (69.2%) with DP-High x DP-High parents belonged to the DP-High group, whereas three out of nine offspring (33.3%) belonged to DP-High group in the case of DP-High x DP-Low mating pairs. No offspring (0%) of two offspring with DP-Low x DP-Low parents belonged to the DP-High group. In addition, heritability (h2: narrow sense) obtained from the regression coefficient of offspring on mid-parent values was 0.54 +/- 0.19. Both findings suggest that increases in DP T cells in cynomolgus monkeys may be genetically controlled.     

Differential effect of neuraminidase-treatment on the surface charge-associated properties of rat reticulocytes and erythrocytes. Studies by partitioning in two-polymer aqueous phases

Rat reticulocytes undergo charge-associated surface changes, detectable by cell partitioning in charged dextran-poly(ethylene glycol) aqueous phase systems, as they become mature erythrocytes. Young reticulocytes have a lower partition coefficient, i.e., quantity of cells in the top phase as a percentage of total cells added, than do mature erythrocytes. Sialic acid is the main charge-bearing group on red blood cells and, in the case of the rat, most of the sialic acid can be removed by treatment of the cells with neuraminidase (Vibrio cholerae). By combining isotopic 59Fe-labeling of reticulocytes with countercurrent distribution of the entire red blood cell population in charged dextran-poly(ethylene glycol) aqueous phases we have now studied the relative effect of neuraminidase-treatment on rat reticulocytes and mature erythrocytes. It was found that neuraminidase-treatment (a) does not eliminate surface differences, detectable by partitioning, between rat reticulocytes and erythrocytes and (b) reduces the partition coefficient of mature erythrocytes to a greater extent than the partition coefficient of reticulocytes indicating a differential effect of this enzyme on the two cell populations.     

Differential effect of neuraminidase-treatment on the surface charge-associated properties of rat reticulocytes and erythrocytes: Studies by partitioning in two-polymer aqueous phases

Rat reticulocytes undergo charge-associated surface changes, detectable by cell partitioning in charged dextran-poly(ethylene glycol) aqueous phase systems, as they become mature erythrocytes. Young reticulocytes have a lower partition coefficient, i.e., quantity of cells in the top phase as a percentage of total cells added, than do mature erythrocytes. Sialic acid is the main charge-bearing group on red blood cells and, in the case of the rat, most of the sialic acid can be removed by treatment of the cells with neuraminidase (Vibrio cholerae). By combining isotopic ⁵⁹Fe-labeling of reticulocytes with countercurrent distribution of the entire red blood cell population in charged dextran-poly(ethylene glycol) aqueous phases we have now studied the relative effect of neuraminidase-treatment on rat reticulocytes and mature erythrocytes. It was found that neuraminidase-treatment (a) does not eliminate surface differences, detectable by partitioning, between rat reticulocytes and erythrocytes and (b) reduces the partition coefficient of mature erythrocytes to a greater extent than the partition coefficient of reticulocytes indicating a differential effect of this enzyme on the two cell populations.     

TNF-α influences the lateral dynamics of TNF receptor I in living cells

In mammalian cells, inflammation is mainly mediated by the binding of tumor necrosis factor alpha to tumor necrosis factor receptor 1. In this study, we investigated lateral dynamics of TNF-R1 before and after ligand binding using high-density single-particle tracking in combination with photoactivated localization microscopy. Our single-molecule data indicates the presence of tumor necrosis factor receptor 1 with different mobilities in the plasma membrane, suggesting different molecular organizations. Cholesterol depletion led to a decrease of slow receptor species and a strong increase in the average diffusion coefficient. Moreover, as a consequence of tumor necrosis factor-alpha treatment, the mean diffusion coefficient moderately increased while its distribution narrowed. Based on our observation, we propose a refined mechanism on the structural arrangement and activation of tumor necrosis factor receptor 1 in the plasma membrane.     

考虑生化刺激的细胞分裂的力学模型

为了解释动物细胞胞质分裂的力学机理 ,基于大量的细胞卵裂实验数据 ,在Zinemanas和Nir的流体动力学模型基础上 ,对微丝的局部集中函数改为随同质膜移动 ,增加了由于生化刺激引起主动微丝的影响系数。数值计算表明 :此模型能较好的预测细胞在胞质分裂过程中 ,细胞的总体和局部变形 ,以及卵裂沟处的张力和细胞内压。     

Analysis of diffusion and relaxation behavior of water in apple parenchymal cells

It has been demonstrated by an example of apple parenchymal cells that NMR spectroscopy can be used to analyze the relaxation and diffusion of water molecules in plant cells. With small diffusion times, three relaxation components have been distinguished, which correspond to water in a vacuole, in the cytoplasm, and in intercellular liquid. The coefficient of self-diffusion corresponding to these components have been determined. With large diffusion times, it is possible to distinguish two components. For the slowly relaxing component (which corresponds to water in a vacuole), the regime of restricted diffusion was observed. For a quickly relaxing component, an anomalous increase in the coefficient of self-diffusion with the time of diffusion took place.     

The transport of univalent thallium across the human erythrocyte membrane

Transport of 204Tl was studied in human erythrocytes incubated in isotonic salt solutions at pH 7.4 and 37 degrees C. 204Tl was rapidly accumulated in cells up to the constant level within a 10 minutes incubation (t0.5 = 3.5 min). The rate of uptake and the distribution ratio decreased in the presence of 0.1 mM ouabain and 0.5-1.0 mM furosemide (t0.5 = 5 min). A broad variability of the coefficient 204Tl distribution was observed in the intact erythrocytes due to a ouabain-sensitive component which was seen to decrease with the increase in Tl+ concentration in the medium (0.005-0.2 mM), and also to depend on the medium ion composition. On the contrary, a passive distribution of 204Tl in the presence of ouabain and furosemide was relatively constant within 1.1-1.5. The steady state distribution of 204Tl was declined after a substitution of Cl- by sucrose in the medium due to depolarization of erythrocyte membrane. On the other side, 204Tl uptake by the cells was raised during hyperpolarization of the membrane in the presence of valinomycin.