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1.
Potassium Transport in Enteromorpha intestinalis (L.) Link: II. EFFECTS OF MEDIUM COMPOSITION AND METABOLIC INHIBITORS 总被引:2,自引:0,他引:2
In springwater (25.5 mol m3 Cl, 20.4 mol m3Na+, 0.14 mol m3 K+) Enteromorpha intestinalis couldnot survive for more than a few weeks unless provided with 0.5mol m3 K+ in the medium or alternatively exposed to seawaterfor 1 day per week. Maintenance of a cytoplasmic K+ level ofabout 200 mol m3 is critical for the maintenance of normalmetabolic activity. Net gains of intracellular K+ occurred whenthe plants were transferred from low-salinity to seawater; converselylarge net losses occurred when plants were transferred fromseawater to springwater. These two processes were not simplythe reverse of one another; net gain of K+ involved a largeincrease in the tracer flux both into and out of the cell butnet loss of K+ virtually halted the tracer flux into the cell.Any injury incurred by rapid salinity changes was short-lived;plants were rapidly able to adjust intracellular [K1.K+). K+(orto some extent Rb+) was found to be necessary in the effluxmedium for 42K+ exchange to occur. The osmotic concentrationof the medium was also important but extracellular Na+ and Clconcentrationswere not critical. K+ influx and efflux in both springwaterand seawater were largely independent of light and were sensitivein varying degrees to a range of common metabolic inhibitorsand uncouplers. The results are best explained by the presenceof an active K+ influx, generated by an ATP-dependent K+ pumpat the plasmalemma. Key words: Enteromorpha, Potassium transport, Salinity changes, Uncouplers, Inhibitors 相似文献
2.
SODIUM TRANSPORT IN ENTEROMORPHA INTESTINALIS (L.) LINK 总被引:1,自引:1,他引:0
3.
The permeability (P) of a lipophilic cation, triphenylmethylphosphonium(TPMP+) which is frequently used as a membrane potential probe,has been measured in Chara australis (Charophyceae). PTPMP+across biological membranes is usually thought to be very highbut this is not the case across the plasmalemma of Chara. Thepermeability of TPMP+ across the plasmalemma was found to betypical of inorganic cations, about 1.0 nm s1. Estimateswere made of the permeability of lipophilic cations across someother cell membranes, based on previously published work. Thepermeability of TPMP+ across the plasma membranes of the redalga, Griffithsia monilis and the blue-green alga, Anabaenavariabilis was about 25 nm s1. The permeabilityof TPMP+ across the plasma membranes of eukaryotes and prokaryotesappears to be similar. The permeability of lipophilic cationsacross the cristae of isolated mitochondria are exceptionallyhigh, about 170 nm s1. TPMP+ did not behave as a thiamineanalogue in Chara, unlike in the case of yeast. The means ofentry of TPMP+ into the Chara cell, driven by the electrochemicalgradient across the plasmalemma, has not been identified. Thepresence of a second lipophilic cation probe, DDA+ (dibenzyldimethylammonium),caused a decrease in the uptake flux of TPMP+; this suggeststhat the two lipophilic cations compete for the same site atthe surface of the plasmalemma. Key words: Chara australis, TPMP+, Permeability, Lipophilic cation 相似文献
4.
immunocytochemical localization of urokinase-type plasminogen activator in lewis lung carcinoma 总被引:1,自引:0,他引:1
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L Skriver LI Larsson V Kielberg LS Nielsen PB Andresen P Kristensen K Dano 《The Journal of cell biology》1984,99(2):753-758
The invasively growing and metasizing Lewis lung carcinoma consistently contained urokinase-type plasminogen activator (u-PA) enzyme activity. When investigated immunocytochemically with antibodies against u-PA, different parts of individual tumors showed a pronounced heterogeneity in staining intensity. Strong staining was found in areas with invasive growth and degradation of surrounding normal tissue, while other areas were completely devoid of staining. Immunoreactivity occurred both with a perinuclear cytoplasmic localization in tumor cells and associated with apparently extracellular material. SDS PAGE of tumor extracts, under both reducing and nonreducing conditions, followed by immunoblotting, showed only one immunocytochemically stainable band with an electrophoretic mobility corresponding to that of purified proenzyme to u-PA, while no two-chain u-PA was detected. This indicates that the major part of the activator in Lewis lung carcinoma is present as one-chain pro-u-PA. 相似文献
5.
6.
The cyanobacterium Synechococcus R-2 (Anacystis nidulans, S. leopoliensis) PCC 7942 has a sodium-dependent chloride transporter 总被引:1,自引:1,他引:0
R. J. RITCHIE 《Plant, cell & environment》1992,15(2):163-177
Synechococcus R-2 (PCC 7942) actively accumulated Cl? in the light and dark, under control conditions (BG-11 media: pHo, 7·5; [Na+]o, 18 mol m?3; [Cl?]o, 0·508 molm?3). In BG-11 medium [Cl?], was 17·2±0·848 mol m?3 (light), electrochemical potential of Cl? (ΔμCl?i,o) =+211±2mV; [Cl?]i= 1·24±0·11 mol m?3(dark), ΔμCl?i,o=+133±4mV. Cl? fluxes, but not permeabilities, were much higher in the light: ?Cl?i,o= 4·01±5·4 nmol m?2 s?1, PCl?i,o= 47±5pm s?1 (light); ?Cl?i,o= 0·395±0·071 nmol m?2 s?1, PCl?i,o= 69±14 pm s?1 (dark). Chloride fluxes are inhibited by acid pHo (pHo 5; ?Cl?i,o= 0·14±0·04 nmol m?2 s?1); optimal at pHo 7·5 and not strongly inhibited by alkaline pHo (pHo 10; ?Cl?1i,o= 1·7±0·14 nmol m?2 s?1). A Cl?in/2H+in coporter could not account for the accumulation of Cl? alkaline pHo. Permeability of Cl? is very low, below 100pm s?1 under all conditions used, and appears to be maximal at pHo 7·5 (50–70 pm s?1) and minimal in acid pHo (20pm s?1). DCCD (dicyclohexyl-carbodiimide) inhibited ?Cl?i,o in the light about 75% and [Cl?]i fell to 2·2±0·26 (4) mol m?3. Valinomycin had no effect but monensin severely inhibited Cl? uptake ([Cl?]i= 1·02±0·32 mol m?3; ?Cl?i,o= 0·20±0·1 nmol m?2 s?1). Vanadate (200 mmol m?3) accelerated the Cl? flux (?Cl?i,o= 5·28±0·64 nmol m?2 s?1) but slightly decreased accumulation of Cl? ([Cl?], = 13·9±1·3 mol m?3) in BG-11 medium but had no significant effect in Na+-free media. DCMU (dichlorophenyldimethylurea) did not reduce [Cl?], or ?Cl?i,o to that found in the dark ([Cl?]i= 8·41±0·76 mol m?3; ?Cl?i,o= 2·06±0·36 nmol m?2 s?1). Synechococcus also actively accumulated Cl? in Na+-free media, [Cl?]i was lower but ΔΨi,o hyperpolarized in Na+-free media and so the ΔμCl?i,o was little changed ([Cl?]i= 7·98±0·698 mol m?3; ΔμCl?i,o=+203±3 mV). Net Cl? uptake was stimulated by Na+; Li+ acted as a partial analogue for Na+. Synechococcus has a Na+ activated Cl? transporter which is probably a primary 2Cl?/ATP pump. The Cl? pump is voltage sensitive. ΔμCl?i,o is directly proportional to ΔΨi,o(P»0·01%): ΔμCl?i,o= -1·487 (±0·102) ×ΔΨi,o, r= -0·983, n= 31. The ΔμCl?i,o increased (more positive) as the Δμi,o became more negative. The ΔμCl?i,o has no known function, but might provide a driving force for the uptake of micronutrients. 相似文献
7.
Abstract Post-construction avifauna investigations were undertaken at Project West Wind, Meridian Energy Limited's 62-turbine wind farm on the Wellington south coast. These investigations were required in accordance with the resource consent conditions to quantify the level of avian mortalities occurring at the wind farm, particularly in regard to New Zealand falcon (Falco novaeseelandiae), kākā (Nestor meridionalis) and kererū (Hemiphaga novaeseelandiae). This is the first comprehensive study at a New Zealand operating wind farm. The methods included three field components necessary to calculate annual estimates of mortalities across the wind farm site: routine turbine searches; carcass detection trials; and carcass removal trials. Results from years 1 and 2 of a three-year programme are presented. To date, mortalities have been recorded for 17 taxa at 18 of the 24 study turbines. There have been no recorded mortalities of falcon, kākā or kererū. Australasian harrier (Circus approximans) has been the species for which the most mortalities have been recorded. Overall estimated annual mortality rates for years 1 and 2 were calculated to be approximately six and five birds per turbine respectively. 相似文献
8.
The additive genetic effects of traits can be used to predict evolutionary trajectories,
such as responses to selection. Non-additive genetic and maternal environmental effects
can also change evolutionary trajectories and influence phenotypes, but these effects have
received less attention by researchers. We partitioned the phenotypic variance of survival
and fitness-related traits into additive genetic, non-additive genetic and maternal
environmental effects using a full-factorial breeding design within two allopatric
populations of Atlantic salmon (Salmo salar). Maternal environmental effects were
large at early life stages, but decreased during development, with non-additive genetic
effects being most significant at later juvenile stages (alevin and fry). Non-additive
genetic effects were also, on average, larger than additive genetic effects. The
populations, generally, did not differ in the trait values or inferred genetic
architecture of the traits. Any differences between the populations for trait values could
be explained by maternal environmental effects. We discuss whether the similarities in
architectures of these populations is the result of natural selection across a common
juvenile environment. 相似文献
9.
Narayana PB Fazolini André LS Cruz Miriam BF Werneck Jo?o PB Viola Clarissa M Maya-Monteiro Patrícia T Bozza 《Cell cycle (Georgetown, Tex.)》2015,14(16):2667-2676
Accumulating evidence suggests that obesity and enhanced inflammatory reactions are predisposing conditions for developing colon cancer. Obesity is associated with high levels of circulating leptin. Leptin is an adipocytokine that is secreted by adipose tissue and modulates immune response and inflammation. Lipid droplets (LD) are organelles involved in lipid metabolism and production of inflammatory mediators, and increased numbers of LD were observed in human colon cancer. Leptin induces the formation of LD in macrophages in a PI3K/mTOR pathway-dependent manner. Moreover, the mTOR is a serine/threonine kinase that plays a key role in cellular growth and is frequently altered in tumors. We therefore investigated the role of leptin in the modulation of mTOR pathway and regulation of lipid metabolism and inflammatory phenotype in intestinal epithelial cells (IEC-6 cells). We show that leptin promotes a dose- and time-dependent enhancement of LD formation. The biogenesis of LD was accompanied by enhanced CXCL1/CINC-1, CCL2/MCP-1 and TGF-β production and increased COX-2 expression in these cells. We demonstrated that leptin-induced increased phosphorylation of STAT3 and AKT and a dose and time-dependent mTORC activation with enhanced phosphorilation of the downstream protein P70S6K protein. Pre-treatment with rapamycin significantly inhibited leptin effects in LD formation, COX-2 and TGF-β production in IEC-6 cells. Moreover, leptin was able to stimulate the proliferation of epithelial cells on a mTOR-dependent manner. We conclude that leptin regulates lipid metabolism, cytokine production and proliferation of intestinal cells through a mechanism largely dependent on activation of the mTOR pathway, thus suggesting that leptin-induced mTOR activation may contribute to the obesity-related enhanced susceptibility to colon carcinoma. 相似文献
10.
R Gon?alves LA Szmuchrowski LS Prado BP Couto JCQ Machado VO Damasceno JA Lamounier 《Biology of sport / Institute of Sport》2015,32(3):255-260
The aim of this study was to assess the suitability of body mass index, waist circumference, waist-to-height ratio and aerobic fitness as predictors of cardiovascular risk factor clustering in children. A cross-sectional study was conducted with 290 school boys and girls from 6 to 10 years old, randomly selected. Blood was collected after a 12-hour fasting period. Blood pressure, waist circumference (WC), height and weight were evaluated according to international standards. Aerobic fitness (AF) was assessed by the 20-metre shuttle-run test. Clustering was considered when three of these factors were present: high systolic or diastolic blood pressure, high low-density lipoprotein (LDL) cholesterol, high triglycerides, high plasma glucose, high insulin concentrations and low high-density lipoprotein (HDL) cholesterol. A ROC curve identified the cut-off points of body mass index (BMI), WC, waist-to-height ratio (WHtR) and AF as predictors of risk factor clustering. BMI, WC and WHR resulted in significant areas under the ROC curves, which was not observed for AF. The anthropometric variables were good predictors of cardiovascular risk factor clustering in both sexes, whereas aerobic fitness should not be used to identify cardiovascular risk factor clustering in these children. 相似文献