METABOLIC RESPONSES OF BAKER'S YEAST TO GLUCOSE ADDITION DURING AEROBIC STARVATION

The kinetics and extent of glucose uptake, ethanol and acetate production, glucose-induced medium acidification and endogenous respiration were studied in baker's yeast starved aerobically for 0, 28, 54 and 96 h in saline (9 g litre^?1 NaCI) at 35°C. Except for the last interval, prolonged starvation brought about an overall increase in most parameters; the transient increase in endogenous respiration observed after glucose addition was lowered with proceeding starvation. A 96 h starvation brought about a change in the kinetics of ethanol production, sharp increase in acetate production and a strong reduction of both the extent and the rate of glucose-induced acidification and of endogenous metabolism.     

Yeast mutants affected in viability upon starvation have a modified phospholipid composition

Selection of mutations, based on the suppression of rvs161Δ defects, was performed. Ten mutants were obtained, ranged amongst four complementation groups, named SUR1, SUR2, SUR3 and SUR4. All sur mutations also suppress a mutation in another gene, RVS167, indicating that all six genes are involved in the same biological pathway. The sur mutant cells have abnormal morphologies in stationary phase, i.e. dumbbell-like in sur1, sur2 or sur3 strains and multibudded in sur4 strains. Several phenotypic characteristics of the physiological suppressors as well as the rvs161Δ strain itself led us to analyse the phospholipid composition of the mutants. The assays show an overall decrease of the phospholipid amounts and modifications in the relative contents of some phospholipid classes in sur mutant cells.     

The problem of obesity: fundamental concepts of energy metabolism gone awry.

The growing prevalence and complex issues related to obesity continue to draw the interest and concern of health researchers and practitioners. This review summarizes pertinent background information on the multiple factors involved in the causes of obesity. Factors such as percentage of body fat, upper- vs. lower-body obesity, family history, past dieting history, and underlying medical conditions should be assessed on an individual basis and applied in the development of successful weight-reducing strategies. The recommended approach to nonpharmacologic intervention for weight loss is to first educate individuals about fat storage and energy balance and then focus on the development of positive behavioral skills such as wise food selections, favorable eating patterns, and regular physical activity. Although preventive measures such as positive eating patterns and exercise habits are ideally acquired in childhood and adolescence, successful weight management can still be achieved in adulthood. The information presented in the following sections provides clinicians with essential material to assist individuals in developing realistic goals at the outset of a weight-control program.     

Mobilisation of bacteria in a fine-grained residual soil by electrophoresis

An investigation of electrokinetic bacterial mobilisation in a residual soil from gneiss is presented here. The experimental program aimed at assessing the efficacy of electrophoresis against the electro-osmotic flow to transport endospores of Bacillus subtilis LBBMA 155 and nitrogen-starved cells of Pseudomonas sp. LBBMA 81. Electrokinesis was performed on a low hydraulic reconstituted clayey soil column submitted to a 5mA electrical current for 24h. Cells were coccoid-shaped and characterised as possessing low surface hydrophobicity and less than 1microm in diameter. Distribution coefficient for B. subtilis in the soil was between 16.8 and 19.9 times higher than that for Pseudomonas sp. Distribution coefficient for B. subtilis between eluate and anionic exchange column was 11.8 times higher than that for Pseudomonas sp. After the electrokinesis, it was shown that cells and endospores were distributed hyperbolically through the soil probe and moved against the electro-osmotic flow; however, endospores were transported throughout all soil core and starved cells only till half of its length. The higher transport efficiency of B. subtilis endospores was attributed to their higher negative charge on cell surface. These results demonstrate that electrokinesis can be used for bacteria transport in soils with low hydraulic conductivity, even against the electro-osmotic flow.     

Use of Starved Cells of a Klebsiella Pneumoniae Strain Isolated from a Brazilian Oil Reservoir in a Transport and Plugging Experiment in a Sandstone Core

Abstract:

Microbial biomass can be used as a plugging agent in high-permeability zones in applications of microbial enhanced oil recover (MEOR) technology to oil-bearing strata. Laboratory tests have shown that bacterial cells, reduced in size by starvation, can penetrate more deeply when injected into a porous medium and also grow therein after nutrient is added. Transport and growth of Klebsiella pneumoniae starved cells through a Rio Bonito sandstone core (440 mD of permeability) were tested, to verify application to oil recovery. The injection of starved cells followed by nutrient medium at a flow rate of 1.8 mL/h, promoted cell growth in the core, which raised the inner pressure from 0.016 to 13.7 psi, resulting in a 99.9% reduction in the permeability of the core. The biobarrier formed persisted during the injection of 4 pore volumes of brine into the core at a flow rate of 1.8 mL/h, keeping the permeability reduced to 99.7%.     

光触发增强葡萄糖氧化酶催化活性的等离子体囊泡用于程序化光热-饥饿疗法

在肿瘤的饥饿治疗及协同治疗中,基于葡萄糖氧化酶(GOx)的纳米诊疗剂展现出具大的应用前景.自组装等离子体金囊泡(GV),由于具有独特的光学性能、巨大空腔和强局域表面等离子体共振等特性,可作为协同治疗的多功能纳米载体.本文中,我们开发了一种装载GOx的GV(GV-GOx)用于光触发释放GOx,同时增强GOx的催化活性,从而实现程序化光热-饥饿治疗.在近红外激光照射下,由于GV具有等离子体耦合效应, GV-GOx可以产生很强的局部高热,引起封装的GOx释放,同时高热可提高GOx催化活性,从而增强肿瘤的饥饿效应.此外,高光热效应可促进细胞对GV-GOx的摄取,并可通过活体光声/光热双模态成像对协同治疗进行有效监测.令人印象深刻的是,协同光热/饥饿疗法能完全消融4T1荷瘤小鼠的肿瘤,抗肿瘤效果明显优于单一疗法,且没有明显的系统毒性.本工作展示了一种光触发的纳米平台,可用于癌症协同治疗.     

程序化饥饿与光动力协同癌症治疗研究（英文）

协同治疗是指将多种治疗方法联合在一起使用,从而显著增强治疗效果.然而,如何设计出理想的组合以最大限度地发挥协同效应仍是肿瘤治疗的一大挑战.在此,我们构建了一种由葡萄糖氧化酶修饰的上转换纳米制剂,用于程序化的肿瘤饥饿-光动力协同治疗研究.葡萄糖氧化酶催化氧化肿瘤内的葡萄糖并产生过氧化氢,该过程消耗葡萄糖和氧气,使得肿瘤细胞缺乏营养物质处于"饥饿"状态,导致细胞死亡.并且在980 nm的近红外光激发下,上转换纳米颗粒激发产生紫外可见光,将双氧水裂解成毒性更强的羟基自由基,进一步杀死肿瘤细胞.体外和体内实验均证实这种饥饿-光动力协同治疗明显优于任何单一治疗.本研究为设计程序可控的饥饿-光动力协同治疗提供了理论支撑.     

太湖流域不同种浮萍淀粉积累的研究

对在太湖采集的15株浮萍进行分子鉴定,从中筛选出3株高淀粉含量浮萍作为供试材料,对其生长培养基进行优化,并研究饥饿条件对其生长和淀粉积累的影响。结果表明:采集到的浮萍分布于5个种,分别为Lemna aequinoctialis,Lemna minor,Lemna turionfera,Spirodela polyrhiza,Landoltia punctata;与SH培养基相比,改良的培养基SH-1和SH-2均能显著促进浮萍的生长;在饥饿试验中,筛选的3种浮萍S.polyrhizza,L.aequinoctialis和L.punctata每周的生长速率(以鲜重计)分别为18.64,20.77和16.52g/m2,饥饿培养33 d后,淀粉含量分别达到20.6%,21.98%和24.30%,较饥饿前分别增加了73.4%,75.4%和137.5%。相较于S.polyrhiza和L.aequinoctialis,L.punctata在淀粉积累方面表现出一定的优势。     

在线氮饥饿处理对谷氨酰胺合成的促进作用

氮饥饿处理是提高谷氨酰胺合成酶活性的重要手段 ,文中设计了在线氮饥饿处理过程 ,考察了氮饥饿处理对谷氨酸棒杆菌突变株NS61 1的谷氨酰胺合成酶活性及谷氨酰胺合成能力的影响。当初始氮源的供应量受到限制时 ,菌体在生长后期处于氮饥饿状态 ,这种氮饥饿处理使菌体内的谷氨酰胺合成酶的活性提高 2倍以上 ,而谷氨酰胺的累积量提高了69%。