Development of biosensor based on immobilized L-glutamate oxidase for determination of monosodium glutamate in food

A monosodium glutamate (MSG) biosensor with immobilized L-glutamate oxidase (L-GLOD) has been developed and studied for analysis of MSG in sauces, soup etc. The immobilized enzymatic membrane was attached with oxygen electrode with a push cap system. The detection limit of the sensor was 1 mg/dl and the standard curve was found to be linear upto 20 mg/dl. Response time of the sensor was 2 min. Cross-linking with glutaraldehyde in presence of Bovine Serum Albumin (BSA) as a spacer molecule has been used for immobilization. Optimization of the sensor was done with an increase in L-GLOD concentration (6.3-31.5 IU) and also with increase in loading volume of enzyme solution (5-20 microl). Optimization of pH and temperature was also studied. The permeability of O2 through different membrane was studied with and without immobilized L-GLOD. The enzymatic membrane was used for over 20 measurements and stability of the membrane was observed.     

不同碳源对大肠杆菌lpdA突变菌累积丙酮酸的影响

为了利用大肠杆菌构建模式"细胞工厂",必须了解在构建过程中各种因素的影响。本研究选用敲除了lpdA基因的大肠杆菌作为模型细胞,考察了该突变菌在合成培养基中利用葡萄糖、果糖、木糖和甘露糖累积丙酮酸的能力。结果显示,在初始糖浓度为10g/L的情况下,lpdA突变菌可以很好地利用葡萄糖、果糖、木糖和甘露糖转化丙酮酸,其得率分别达到了0.884g/g、0.802g/g、0.817g/g和0.808g/g,且在以葡萄糖、果糖和木糖发酵时,丙酮酸的积累过程与细胞生长偶联。甘露糖发酵的情况则不同:菌浓度很快达到平台期,随后丙酮酸积累和甘露糖消耗都表现为线性变化。当在考察了不同的接种量对lpdA突变菌发酵葡萄糖的影响时发现,大接种量能加快葡萄糖消耗速率、丙酮酸的积累速率和细胞生长速率,但丙酮酸得率却明显下降。这些结果对构建以大肠杆菌为母体的模式"细胞工厂"有参考价值。     

EFFECT OF COCAINE ON THE GROWTH OF LUPINUS ALBUS. A CONTRIBUTION TO THE COMPARATIVE PHARMACOLOGY OF ANIMAL AND PLANT PROTOPLASM

1. The effects of cocaine and its decomposition products were studied on the growth of the young roots of Lupinus albus. 2. The results obtained were compared with similar experiments on animal tissues. 3. It was found that, while cocaine is the most toxic of these compounds studied for animal tissues, it was of comparatively low toxicity in respect to its effect on the growth of roots. On the other hand, sodium benzoate, being practically non-toxic for animals, was the most toxic of the compounds studied for the plant roots.     

Effects of prolonged administration of high molecular levan on arterial blood gases, oxygen transport and acid base balance in rabbits.

The effect of daily intraperitoneal injections of 100 mg of high molecular levan for 4-6 weeks on a number of physiological parameters was studied in rabbits. The parameters studied included whole blood pH, blood gases and acid-base balance. Control rabbits were similarly treated with physiological saline. In five rabbits T-50 was determined after levan treatment. None of the studied parameters was significantly affected by the levan treatment.     

Effects of organic fluorosilicone compounds on the development of tumors in mice

The influence of new synthesized fluoro-silicium-organic complexes on the virus-induced Rauscher leukosis and cell-transferred MX-11 mouse sarcoma was studied. We also studied the cytotoxic effects of these complexes in vitro in the human CaOv cells. Two complexes from seven studied were cytotoxic for CaOv cells. Five complexes from seven studied diminished the mortality of animals with MX-11 tumors on the 27-th day of observation, but the total life duration of the animals in the experimental group was the same as in controls. One complex from seven studied increased the life duration of mice with MX-11 tumors. No effects were noted in relation to mice virus-induced Rauscher leukosis.     

Erythrocyte sorbitol dehydrogenase of selected non-mammalian vertebrates

Erythrocyte sorbitol dehydrogenase activity (EC 1.1.1.14) from selected non-mammalian vertebrates was studied showing great variability not related to their phylogenetical position. The Michaelis-Menten constant (Km) for sorbitol exhibited moderate low values in the studied animals. In snakes the Km for sorbitol was low with moderate activity of sorbitol dehydrogenase, suggesting that the enzyme could reach maximum activity with lower sorbitol concentration in comparison to other vertebrates. In the snakes the enzyme showed the same affinity for all the studied polyols, indicating that we are probably dealing with a very ancient enzyme, an unspecific enzyme.     

云南秋海棠挥发物抗微生物活性的研究

对云南产的16种秋海棠属（Begonia L．）植物进行了挥发物抗微生物活性实验,其中14种秋海棠为首次报道。结果表明,在所研究的16种秋海棠中,有8种秋海棠具有抗葡萄球菌（Staphyllococcus epidermidis）活性。而抗大肠杆菌（Escherichia coli）活性最强的是厚壁秋海棠（Begonia silletensis C．B．Clarke）,假厚叶秋海棠（B．pseudodryadis C．Y．Wu）和秋海棠（B．grandis Dryand．）。只有铁甲秋海棠（B．masoniana Irmsch．）和毛叶秋海棠（B．rex Putz．）对白假丝酵母菌（Candida albicans）有抗性。作为室内盆栽花卉被广泛应用的秋海棠,不仅可以美化室内环境,而且还可以作为药用和净化室内环境的生态产品进行推广应用。     

Some properties of acetylcholinesterase from rat retina.

Acetylcholinesterase (AChE, EC 3.1.1.7) of rat retina was studied with respect to its kinetic and other properties, and a comparison was made with the enzyme from brain. The subcellular distribution of the retinal AChE showed that the enzyme was concentrated in the synaptosomal-mitochondrial fraction although in the brain the AChE was distributed more evenly between the fractions studied. The enzyme from both retina and brain was easily solubilised and exhibited a Km of the order of 10(-4) M. The pH optimum was 8.3-8.6 for the AChE from both tissues for both the soluble and particulate enzyme.     

BIOSYNTHESIS OF RIBONUCLEIC ACID IN RAT BRAIN SLICES

The incorporation of uridine into RNA in brain slices was studied. Optimal conditions for uridine incorporation were determined. The characteristics of the product suggest that de novo DNA-directcd synthesis of fairly high molecular weight material takes place. Incorporation into RNA of several areas of brain was studied. The incorporation was also studied as a function of the age of the animal. Finally, an apparent correlation was observed between the decrease in uridine incorporation with age and the increase of the enzyme uridine nucleosidase which hydrolyses uridine to uracil, a material which cannot be incorporated into RNA.     

Reduction of active elastase concentration by means of immobilized inhibitors: a novel therapeutic approach

The inhibitory power of three different active Nylon membranes, separately loaded with three different protease inhibitors, was studied with the aim of reducing the increased elastase concentration occurring during hemodialysis or extracorporeal blood circulation in patients undergoing cardiopulmonary bypass. Chemical grafting was carried out to make the inert Nylon membrane suitable for the immobilization of the inhibitors. The behavior of immobilized alpha(1)-antitrypsin, bovine pancreatic trypsin inhibitor (BPTI), or elastatinal was separately studied. alpha(1)-Antitrypsin and BPTI were covalently immobilized by means of a diazotization process, whereas elastatinal was covalently attached via a condensation process mediated by glutaraldehyde. The inhibitory power of each membrane type was studied as a function of the amount of immobilized inhibitor and temperature. All active membranes have shown good inhibitory power. The most efficient membrane was that loaded with alpha(1)-antitrypsin, the less efficient that with BPTI.     

Profiling of selected indigenous rice (Oryza sativa L.) landraces of Rarh Bengal in relation to osmotic stress tolerance

A total of ten rare indigenous rice landraces of West Bengal were screened for germination potential and seedling growth under varying concentrations of sodium chloride (NaCl) and polyethylene glycol (PEG) solutions as osmotic stress inducing agents. Among the studied rice landraces Kelas and Bhut Moori showed highest degree of tolerance to induced osmotic stresses. Proline content of the studied lines was also determined. Genetic relationship among the studied rice landraces was assessed with 22 previously reported osmotic stress tolerance linked Simple Sequence Repeat (SSR) markers. The identified allelic variants in form of amplified products size (molecular weight) for each SSR marker were documented to find out allele mining set for the linked markers of the studied genotypes in relation to osmotic stress tolerance. A Microsatellite Panel was constructed for the different allelic forms (size of amplified products) of each used marker. Among 22 SSR markers, ten showed unique alleles in form of single specific amplified product for the studied four genotypes which can be used for varietal identification. Genetic relationship among the studied rice lines was determined and a dendrogram was constructed to reveal their genetic inter-relationship. Polymorphism Information Content (PIC) for each used marker was also calculated for the studied rice lines.     

Simultaneous determination of ten active components in traditional Chinese medicinal products containing both Gegen (Pueraria lobata) and Danshen (Salvia miltiorrhiza) by high-performance liquid chromatography

In order to facilitate the quality control of Traditional Chinese Medicine (TCM) products containing both Gegen (Pueraria lobata) and Danshen (Salvia miltiorrhiza), a new and simple HPLC method for the simultaneous determination of 10 active components in these products has been developed. The chromatographic separation was carried out on a C(18) column eluted with a mobile phase consisting of 0.1% acetic acid in water and 0.1% acetic acid in acetonitrile with gradient elution. The eluent was monitored by a photodiode array UV detector at a wavelength of 250 nm for Gegen components including puerarin, daidzein 8-C-apiosyl-glucoside, daidzin and daidzein, and at 270 nm for Danshen components including danshensu, protocatechuic aldehyde, salvianolic acid B, cryptotanshinone, tanshinone I and tanshinone IIa. Excellent chromatographic separation was achieved for all studied compounds with good linearity (r(2)> 0.999) over the studied concentration ranges. The developed method has been applied to the simultaneous determination of the 10 studied compounds in commercially available products containing both Gegen and Danshen. The TCM product samples were extracted by sonication with a mixture of methanol:water (80:20) containing 0.5% acetic acid. Extraction recoveries for all studied compounds were in the range of 96.01-106.18%. The intra-day and inter-day variations were less than 7.25 and 5.44%, respectively, for all studied compounds. The developed method has not only proved to be effective in the simultaneous determination of the 10 components, but also provides a convenient quality control approach for TCM products containing both Gegen and Danshen.     

Perception of effort in isometric and dynamic muscular contraction.

The perception of muscular effort was studied using estimation and production methods in the adductor pollicis and quadriceps. A psychometric scale (percentage magnitude) was used. Static contractions were studied in the adductor pollicis, and both dynamic (isokinetic) and static contractions were studied in quadriceps. Linear and logarithmic equations were fitted for the perceived effort as a percentage of the maximum in relation to the produced percentage maximal force or torque. The logarithmic exponent was around or above 1.0. No significant difference was found between mean exponent and intercept values for the adductor pollicis and the quadriceps, or when estimated or produced values for the two muscles were compared. There was no difference in the same subjects between the equations for static and dynamic contractions with low angular velocity of the quadriceps.     

Stability of recombinant plasmids on the continuous culture of Bifidobacterium animalis ATCC 27536

Bifidobacterium animalis ATCC 27536 represents among bifidobacteria a host-model for cloning experiments. The segregational and structural stabilities of a family of cloning vectors with different molecular weights but sharing a common core were studied in continuous fermentation of the hosting B. animalis without selective pressure. The rate of plasmid loss (R) and the specific growth rate difference (delta mu) between plasmid-free and plasmid-carrying cells were calculated for each plasmid and their relationship with plasmid size was studied. It was observed that both R and the numerical value of delta mu increased exponentially with plasmid size. The exponential functions correlating the specific growth rate difference and the rate of plasmid loss with the plasmid molecular weight were determined. Furthermore, the smallest of the plasmids studied, pLAV (4.3-kb) was thoroughly characterized by means of its complete nucleotide sequence. It was found that it contained an extra DNA fragment, the first bifidobacterial insertion sequence characterised, named IS 1999.     

Monomorphism of isoenzyme loci in natural and cultivated amaranth (Amaranthus L.) populations

Starch gel electrophoresis was used for isozyme analysis of ADH, GDH, MDH, IDH, and ME in populations of amaranth. Experiments were performed with 93 populations and 4 cultivars. Some populations proved to be polymorphic, and this fact allowed analysis of the genetic control of the enzymes listed. The populations examined showed poor allozyme variability. Monomorphism for all loci studied was observed in 73 populations and 4 varieties. Starch gel electrophoresis was used for isozyme analysis ofADH, GDH, MDH, IDH, and ME in populations of amaranth. Experiments were performed with 93 populations and 4 cultivars. Some populations proved to be polymorphic, and this fact allowed analysis of the genetic control of the enzymes listed. The populations examined showed poor allozyme variability. Monomorphism for all loci studied was observed in 73 populations and 4 varieties. Only some populations demonstrated rare polymorphism for a single locus each: Adh, Mdh 2, Gdh, Idh 1, Idh 2, or Mod 2. The results demonstrate genetic monomorphism of amaranth for the studied loci.     

Coimmobilization of substrate and biocatalyst: A method for bioconversion of poorly soluble substances in water milieu

Coimmobilization of biocatalyst and substrate was studied as a method to increase the conversion rate in systems with substrates of extremely low solubility in water. The system studied was the conversion of hydrocortisone to prednisolone by Arthrobacter simplex. As a matrix for coimmobilization, alginate turned out to be superior to agar and agarose. After the reaction was complete, the beads were solubilized, andthe cells recovered for reuse, by centrifugation, whereas the prednisolone was extracted from the supernatant.     

Properties of a collagen and monomycin complex]

The prolonged effect of a single application of a collagen-monomycin sponge was studied experimentally on albino rats on a model of a skin flat wound. The monomycin levels in the blood and tissues in the area of the sponge application for 14 days were determined by the biological method. The therapeutically effective concentration of monomycin, i.e. 3.8 gemma/ml was maintained in the general blood flow for 2 weeks. During this period the local antibiotic concentration was almost 5 times higher. The toxic effect of the collagen-monomycin complex was studied on rabbits and albino rats for 2 months with respect to the indices of the protein metabolism and the content of residual nitrogen and urea. The activity of cholinestrerase and the content of histamine in the blood were determined. No significant changes in the studied tests were observed during the period of the chronic experiment. The microstructure of the organs of the test animals did not differ from that of the intact animals. The collagen-monomycin complex had a prolonged antibacterial effect and was not toxic with respect to the the test animal.     

Sterol affinity of Candida albicans cells resistant to polyene antibiotics]

The affinity levels of sterols in the sensitive and resistant cultures of C. albicans for polyenic antibiotics were studied comparatively. The affinity level was determined by liberation of potassium under the effect of the antibiotic participating in interaction with the sterol. The protective effect of the sterol suspended in solution and included into the composition of the liposomes from egg lecithin was studied. It was found that the sterols of the resistant cultures of C. albicans had the same (or even somewhat higher) affinity to amphotericin B as those from the sensitive cultures. The data indicate that resistance of the strains studied is not based on the loss of the sterol capacity for binding polyenic antibiotics.     

桃花粉离体萌发和花粉管生长特性研究

采用花粉离体萌发法研究不同培养基组分和培养条件对桃花粉萌发和花粉管生长的影响,同时对不同贮藏温度下的桃花粉寿命进行研究.结果表明:固体培养基与液体培养基对桃的花粉萌发率和花粉管长度影响差异不显著;10%蔗糖是大多数桃品种花粉的最适萌发条件;硼能提高桃花粉的萌发率,但对花粉管的生长没有促进作用;桃花粉在20℃～25℃的培养温度下萌发率最高,花粉管最长;桃花粉萌发率和花粉管长度在培养前3 h内上升最快,3～5 h上升趋势减弱,5 h后基本停止;随着贮藏温度的升高和贮藏时间的延长,花粉生活力呈降低的趋势.