Madin–Darby canine kidney cells are increased in aerobic glycolysis when cultured on flat and stiff collagen‐coated surfaces rather than in physiological 3‐D cultures

We investigate the influence of the dimensionality and the biochemistry of the culture system on the cellular functionality by analyzing the protein expression levels in Madin–Darby canine kidney (MDCK) cells grown in 3‐D and 2‐D substrates. We cultured MDCK cells on a hard and flat 2‐D uncoated plastic surface, on a 2‐D collagen‐coated plastic surface and in 3‐D collagen gel and employed 2‐D gel electrophoresis, MALDI‐TOF‐MS, and LC‐MS/MS analysis to identify the differentially regulated proteins. We found significant differences in the expression of antioxidant proteins, actin‐binding proteins, glycolytic enzymes, and heat‐shock proteins/chaperons among the three types of cultures. While MDCK cells cultured in 3‐D collagen up‐regulate antioxidant proteins and proteins involved in the dynamic remodeling of the actin cytoskeleton, 2‐D collagen‐coated plastic surfaces induce the up‐regulation of glycolytic enzymes. Our data shows that the culture conditions have profound effects on the physiology of the cell. Culture in 3‐D collagen induces a differentiated polarized phenotype. In contrast, collagen‐coated 2‐D substrates favor a tumor‐like phenotype with increased glycolysis. Thus, the suitability of 2‐D cultures to study the physiological behavior of cells, especially in drug discovery, bioprocessing, and toxicology, should be carefully reconsidered.     

我国公立医院提升文化力路径探究

通过对公立医院文化力缺失的原因及其重要性的分析,提出公立医院提升文化力的路径。以文化力的提升形成医院的文化合力,并籍此来化解医患矛盾,创造和谐医患关系,树立医院文化形象,提升医院核心竞争力。     

Cultural transmission of tool use by Indo-Pacific bottlenose dolphins (Tursiops sp.) provides access to a novel foraging niche

Culturally transmitted tool use has important ecological and evolutionary consequences and has been proposed as a significant driver of human evolution. Such evidence is still scarce in other animals. In cetaceans, tool use has been inferred using indirect evidence in one population of Indo-Pacific bottlenose dolphins (Tursiops sp.), where particular dolphins (‘spongers’) use marine sponges during foraging. To date, evidence of whether this foraging tactic actually provides access to novel food items is lacking. We used fatty acid (FA) signature analysis to identify dietary differences between spongers and non-spongers, analysing data from 11 spongers and 27 non-spongers from two different study sites. Both univariate and multivariate analyses revealed significant differences in FA profiles between spongers and non-spongers between and within study sites. Moreover, FA profiles differed significantly between spongers and non-spongers foraging within the same deep channel habitat, whereas the profiles of non-spongers from deep channel and shallow habitats at this site could not be distinguished. Our results indicate that sponge use by bottlenose dolphins is linked to significant differences in diet. It appears that cultural transmission of tool use in dolphins, as in humans, allows the exploitation of an otherwise unused niche.     

Comparison of the pacemaker properties of chick embryonic atrial and ventricular heart cells

Summary We have investigated the pacemaker properties of aggregates of cells dissociated from the atria and ventricles of 10 to 14-day-old chick embryonic hearts using a two-microelectrode current and voltage-clamp technique. These preparations usually beat spontaneously and rhythmically in tissue culture medium containing 1.3mm potassium with a beat rate typically in the range of 15–60 beats per minute. The beat rate results show considerable variability, which precludes any statistically significant comparison between the spontaneous activity of atrial and ventricular cell preparations at 10–14 days of development. However, the shapes of pacemaker voltage changes do exhibit differences characteristic of cell type. Spontaneous atrial preparations rapidly depolarize from maximum diastolic potential (–90 mV) to a plateau range of pacemaker potentials (–80 to –75 mV). The membrane subsequently depolarizes more gradually until threshold (–65 mV) is reached. In contrast, spontaneously beating ventricular cell preparations slowly hyperpolarize after maximum diastolic potential to the –100 to –95 mV range before gradually depolarizing toward threshold. Voltage-clamp analysis reveals a virtual lack of any time-dependent pacemaker current in atrial preparations. These preparations are characterized by an approximately linear background current (I _bg) having a slope resistance of 100 K cm². Ventricular preparations have a potassium ion pacemaker current with slow kinetics (I _{K 2}), and a second time-dependent component (I _x) which is activated at potentials positive to –65 mV. The background current of these preparations displays inward rectification. Computer simulations of pacemaking reveal that the initial rapid phase of pacemaker depolarization in atrial cells is determined by the membrane time constant, which is the product of membrane capacitance and the slope resistance ofI _bg. The hyperpolarization after maximum diastolic potential of ventricular cells is caused byI _{K 2}. The final slow phase of depolarization in both cell types is caused in part by the steady-state amplitude of the fast inward sodium current (I _Na). This component has negative slope conductance which effectively increases the slope resistance in the vicinity of threshold compared to TTX-treated preparations. This mechanism is sufficient to produce interbeat intervals several seconds in duration, even in the absence of time-dependent pacemaker current, provided that the background current is at the appropriate level.     

Demonstration of 2',3'-Cyclic Nucleotide 3'-Phosphohydrolase in Cultured Human Schwann Cells

Abstract: Schwann cell cultures were established from adult human sural nerve biopsies. 2'3'-Cyclic nucleotide 3'-phosphohydrolase (CNPase) activity was estimated in the homogenates of those cells by a sensitive isotope assay using [³H]2',3'-cyclic AMP as substrate. A high level of CNPase activity was observed in cultured Schwann cells, whereas cultured human muscle and skin fibroblasts contained negligible levels of CNPase activity. CNPase of human Schwann cells followed typical enzyme-substrate kinetics, with an apparent K _m of 1.6 m M for 2',3'-cyclic AMP, and the enzyme was stimulated by detergents such as Triton X-100 and deoxycholate. It was inhibited by p -chloromercuricbenzoate and 2'-AMP. These properties are typical of CNPase isolated from adult brain and spinal cord. CNPase can serve as a new biochemical marker of normal cultured human Schwann cells and can be useful in analyzing the properties of cultured Schwann cells from patients with dysschwannian neuropathies.     

Optimizing nutritional conditions for the liquid culture production of effective fungal biological control agents

Spores of fungal pathogens of weeds and insects are unique in their ability to actively infect and kill their pest host. While these capabilities are advantageous in terms of their use as a contact biological control agent, or biopesticide, they also require special consideration during spore production. Directed approaches to medium optimization must consider not only spore yield but also spore qualities such as desiccation tolerance, stability as a dry preparation, and biocontrol efficacy. Nutritional conditions during culture growth and sporulation should direct the accumulation of appropriate endogenous reserves so that newly formed spores possess these advantageous qualities. Studies with the bioherbicidal fungus Colletotrichum truncatum and with the bioinsecticidal fungus Paecilomyces fumosoroseus have demonstrated the impact of nutrition on spore ‘fitness’ for use as a biological control agent. The optimization strategy used in these nutritional studies as well as a comparison of the results are presented. Received 06 February 1997/ Accepted in revised form 29 May 1997     

Conversion of DOPA to tetrahydroisoquinolines and stizolobic acid in a callus culture of Stizolobium hassjoo

Isolation and identification of l-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline and l-1-methyl-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline from seeds and callus of S. hassjoo are described. Administration of [β-¹⁴C]-labelled DOPA to a callus culture of this legume resulted in the incorporation of radioactivity into l-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, l-1-methyl-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline and stizolobic acid, which was confirmed by constant specific radioactivity after co-crystallization with authentic samples of each compound.     

Use of a non-volatile thiocarbamate to select for herbicide-tolerant tobacco cell lines

A method is described for using the non-volatile thiocarbamate R-14705 (S-3-methylpyridyl N,N-di-butyl-thiocarbamate) to select for herbicide-tolerant tobacco in cell culture. Properties of two selected cell lines are described. Both lines were stably resistant to R-14705 in the absence of continuous selection, and showed significant cross-resistance to commercial thiocarbamate herbicides. The concept of using analogs to solve problems caused by physical properties of a potential selective agent is discussed.     

毛叶秋海棠叶片组织培养快速繁殖

毛叶秋海棠（Begonia rex Puts.）通常是用叶片进行繁殖。但繁殖系数不高,在短期内要得到大量繁殖植株是有困难的。采用离休叶片进行组织培养,能够做到快速无性繁殖。