Effects of ionizing radiation on the growth and allyl isothiocyanate accumulation of Wasabia japonica in vitro and ex vitro

Mutations were induced in tissue-cultured wasabi (Wasabia japonica Matsumura) by treating in vitro-derived shoot tips with either γ-rays or X-rays at 0, 10, 20, 40 or 80 Gy. Doses of up to 40 Gy of either γ- or X-ray treatments resulted in a survival rate of more than 60% in culture after 3 mo. The use of γ- or X-rays at doses between 10 Gy and 40 Gy to induce mutation in W. japonica resulted in an alteration of the growth and allyl isothiocyanate (AITC) content of multiple shoots after 3 mo. in culture on Murashige and Skoog medium containing 5 μM N⁶-benzyladenine (BA). Putative mutants from the 40 Gy treatments of either γ- or X-rays exhibited a reduction in shoot weight, number, and height, whereas treatments of either γ-rays or X-rays at 10 Gy and 20 Gy doses showed no significant differences in shoot growth. All shoots treated with 80 Gy were either necrotic or irregenerable, while those treated with 40 Gy produced deformed leaves, from both types of ionizing radiation. Concentrations of AITC were measured by the use of gas chromatography-mass spectrometry (GC-MS). The accumulation of AITC was shown to decrease when doses increased in both γ- and X-ray treatments, compared with the controls. Positive responses were solely occurred at 18 mo. after transfer of in vitro rooted shoots to the shade house. The survival rate, rhizome weight and AITC content of plants derived from shoots treated with 20 Gy or 40 Gy of either γ-rays or X-rays were significantly greater than those of the controls.     

Identification and Determination of 1-Methylimidazole-4-Acetic Acid in Human Cerebrospinal Fluid by Gas Chromatography-Mass Spectrometry

Abstract: A method for the quantification of 1-methylimidazole-4-acetic acid in human CSF was developed. Methylimidazole-acetic acid was identified and quantitated in CSF. The method involves concentration of the compound on a cation exchanger, extraction of the methyl ester with ethyl acetate, and preparation of a heptafluorobutyryl derivate of the methyl ester, which is finally purified by chromatography on silica gel and quantitated by gas chromatography-mass spectrometry with the deuterated analogue as internal standard. The coefficient of variation at 1 ng/ml was 13%. The limit of sensitivity was about 0.2 ng/ml. The concentration of methylimidazole-acetic acid in lumbar CSF from healthy volunteers was below 1 ng/ml. Ventricular CSF contained higher concentrations than lumbar fluid. The existence of a rostrocaudal concentration gradient was established. There was a correlation between the concentration of methylimidazole-acetic acid and tele-methylhistamine in CSF. The concentration of methylimidazole-acetic acid in lumbar CSF from schizophrenic patients, patients with subarachnoidal haemorrhage, or patients with rheumatic disease was in the range of that in healthy volunteers.     

An improved clearing method for GUS assay inArabidopsis endosperm and seeds

Precise cellular localization of the GUS stain is notoriously difficult inArabidopsis seeds. Here we report an improved protocol for the clearing of seeds after GUS staining. Incubation in ethanol-acetic acid (EtAc) and Hoyer’s medium allows reliable cellular localization of the GUS, even in seeds from late developmental stages. This method also leads to the staining of nucleoli in the endosperm and embryo, facilitating nuclear counts in endosperm development. An erratum to this article is available at .     

Psidium guajava Paluma responses to environmental conditions and ozone concentrations in the urban forest of São Paulo,SE-Brazil

Tropospheric ozone concentrations (O₃) are continuously increasing with harmful effects on vegetation. Ozone uptake triggers oxidative stress that may promote adverse changes in various plant physiological processes. The aim of this study was to evaluate the relationship between meteorological conditions and O₃ exposure in foliar injuries, gas exchanges and antioxidant enzyme activity in Psidium guajava Paluma. Saplings of Paluma were exposed in a site contaminated by O_3. Foliar injuries, gas exchanges, and the activity of superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) were evaluated weekly. Results were analyzed by multivariate analysis. The O₃ exposure reduced carbon assimilation and induced the onset of foliar injuries. The enzymatic activities were more related to meteorological conditions than to O₃ exposure, indicating that these enzymes are not this species’ first line of defense. However, our finding indicates that Paluma may be considered a response indicator, given its presentation of foliar injuries even at low O₃ concentrations.     

Release of N-Acetylaspartylglutamate from Slices of Rat Cerebellum, Striatum, and Spinal Cord, and the Effect of Climbing Fiber Deprivation

Abstract: The release of endogenous N -acetylaspartylglutamate (NAAG) from slices of rat cerebellum, striatum, and spinal cord upon depolarization with 50 m M K⁺ was investigated. NAAG in superfusates was prepurified using an ion exchanger, esterified, and then quantified by gas chromatography-mass spectrometry. Deuterated NAAG was used as internal standard. A depolarization-induced release of NAAG was found in all three regions. The release was Ca²⁺ dependent to over 85% in cerebellum and striatum, but only to approximately 70% in spinal cord. In addition, the effect of lesions of the olivocerebellar pathway on the K⁺-induced release of NAAG was studied: Treatment of the animals with 3-acetylpyridine reduced the release of NAAG from cerebellar hemispheres significantly, by about 40% compared with controls. These results suggest that part of the NAAG released from cerebellar slices on depolarization is related to climbing fibers. Implications of these findings concerning possible physiological roles of NAAG in the three CNS regions are discussed.     

The effect of gas double-dynamic on mass distribution in solid-state fermentation

The mass distribution regularity in substrate of solid-state fermentation (SSF) has rarely been reported due to the heterogeneity of solid medium and the lack of suitable instrument and method, which limited the comprehensive analysis and enhancement of the SSF performance. In this work, the distributions of water, biomass, and fermentation product in different medium depths of SSF were determined using near-infrared spectroscopy (NIRS) and the developed models. Based on the mass distribution regularity, the effects of gas double-dynamic on heat transfer, microbial growth and metabolism, and product distribution gradient were systematically investigated. Results indicated that the maximum temperature of substrate and the maximum carbon dioxide evolution rate (CER) were 39.5 °C and 2.48 mg/(h g) under static aeration solid-state fermentation (SASSF) and 33.9 °C and 5.38 mg/(h g) under gas double-dynamic solid-state fermentation (GDSSF), respectively, with the environmental temperature for fermentation of 30 ± 1 °C. The fermentation production (cellulase activity) ratios of the upper, middle, and lower levels were 1:0.90:0.78 at seventh day under SASSF and 1:0.95:0.89 at fifth day under GDSSF. Therefore, combined with NIRS analysis, gas double-dynamic could effectively strengthen the solid-state fermentation performance due to the enhancement of heat transfer, the stimulation of microbial metabolism and the increase of the homogeneity of fermentation products.     

Effects of Water on Enzyme Performance with an Emphasis on the Reactions in Supercritical Fluids

ABSTRACT

Enzymes require a certain level of water in their structures in order to maintain their natural conformation, allowing them to deliver their full functionality. Furthermore, as a modifier of the solvent, up to a certain level, water can modify the solvent properties such as polarity/polarizability as well as the solubility of the reactants and the products. In addition, depending on the type of the reaction, water can be a substrate (e.g., in hydrolysis) or a product (e.g., in esterolysis) of the enzymatic reaction, influencing the enzyme turnover in different ways. It is found that regardless of the type of reaction, the functionality of enzyme itself is maximum at an optimum level of water, beyond which the enzyme performance is declined due to the loss in enzyme stability. Furthermore, mass transfer limitations caused by pathway blockage and/or by reduced solubilities of the reactants and/or products can also affect the enzyme performance at higher water levels. Controlling water content of ingoing CO₂ and substrates as well as precise management of enzyme support and salt hydrates are important strategies to adjust water level in reaction media, especially in supercritical environments.     

气相色谱法测定食品中的抗氧化剂BHA，BHT，TBHQ

本文利用甲醇和石油醚直接提取油脂和含油脂食品中的抗氧化剂丁基羟基茴香醚(BHA),二丁基羟基甲苯(BHT),特丁基对苯二酚(TBHQ),建立同时测定这三种抗氧化剂的气相色谱方法。采用安捷伦HP-5毛细管柱(i.d.0.25μm×30.0m),氢火焰离子化检测器,外标法定量测量,经实验,样品加标回收率为95%-104%,检出限分别为BHA:0.22 mg/L,BHT:0.23 mg/L,TBHQ:0.33 mg/L。该方法具有前处理操作简便,灵敏度高,重现性好等优点。     

3种碱蓬属植物种子含油量及其脂肪酸组成研究

应用重量法和气相色谱-质谱联用技术（GC-MS）对吉林省西部盐碱地生长的碱蓬、角碱蓬和翅碱蓬3种野生植物的种子含油量及脂肪酸成分进行了测定和分析。结果表明：碱蓬、角碱蓬和翅碱蓬种子含油量分别为24．39％、15．67％和15．80％。不饱和脂肪酸含量分别为88．65％、88．30％、88．50％。尤其是亚油酸含量较高,分别达56．94％、59．35％和60．86％。利用盐碱荒地种植碱蓬属植物。充分开发其在食用、医疗保健方面的应用价值。具有巨大潜力和广阔前景。     

Structured fiber supports for gas phase biocatalysis

Pseudomonas cepaciae lipase adsorbed onto non-porous structured fiber supports in the form of woven fabrics, was used to catalyze hydrolysis and transesterification reactions in the gas phase. The enzyme adsorbed onto carbon fiber support exhibited much higher catalytic activity compared to the enzyme immobilized onto glass fiber carrier. The effect of temperature and relative humidity on reactions catalyzed by P. cepaciae lipase adsorbed onto structured fiber carbon support was studied in the gas system. Under the conditions investigated (up to 60 °C and 80% relative humidity), the immobilized enzyme showed a high thermostability and could be efficiently used to catalyze hydrolytic and transesterification reactions in continuous mode. Structured fiber supports, with a high specific surface area and a high mechanical resistance, showed a low-pressure drop during the passage of reactants through a reactor. The approach proposed in this study could be suitable for immobilization of a wide variety of enzymes.