课程文献中心 更多>>

关键词： Sweet cherry   Surface pitting   Cell wall enzymes   Metabolomic  

摘要： One important physiological disorder in sweet cherry (Prunus avium L.) is surface pitting. This disorder involves irregular depressions on the fruit surface and occurs during harvest, but it develops during cold storage. The aim of this research was to understand the phenotypic characteristics and biochemical responses, referring to the metabolomic profile and the composition and disassembly of the cell wall, that underlie the susceptibility to pitting. The study was carried out using cultivars with contrasting pitting behaviors, such as Bing (resistant) and Sweetheart (sensitive), during ripening and postharvest storage. Induced pitting did not have a negative impact on quality parameters except visual quality in sweet cherries during cold storage, and firmness was not a key parameter that explained the susceptibility to pitting. The mechanical stress to induce pitting triggered a significant decline in pectin methylesterase (PME) activity on day 14 of storage for the Sweetheart cultivar. Intensified labeling for methylated homogalacturonan immunostaining of pitted mesocarp cells in Bing was observed. Xyloglucan showed more abundant labeling in pitted samples, which was more pronounced in Sweetheart fruit than Bing cherries. The metabolomic screening showed a higher content of organic acids and amino acids in the Sweetheart cultivar, while the Bing cultivar had higher contents of sorbitol and arabinitol. Proline and 2-oxoglutaric acid emerged as metabolites altered in response to mechanical stress in both cultivars. Furthermore, pitted Bing fruit elicits anthocyanin overexpression. The metabolomic analysis suggests that susceptibility to pitting could depend on the metabolic differences of each cultivar because the induced pitting did not greatly disrupt the studied metabolic responses.

关键词： Mannose   Mannose isomerase   Characterization   Pseudomonas syringae   Mannose production  

摘要： d-Mannose isomerase can reversibly catalyze d-fructose to d-mannose which has various beneficial effects. A novel d-mannose isomerase gene (PsMIaseA) from Pseudomonas syringae was cloned and expressed in Escherichia coli. The recombinant d-mannose isomerase (PsMIaseA) showed the highest amino acid sequence homogeneity of 50% with ManI from Thermobifda fusca. PsMIaseA was purified through Ni-NTA chromatography, and its specific activity was 818.6 U mg(-1). The optimal pH and temperature of PsMIaseA were pH 7.5 and 45 degrees C, respectively. The enzyme was stable within a wide pH range from 5.0 to 10.0. It could efficiently convert d-fructose to d-mannose without any metal ions. When PsMIaseA was incubated with 600 g/L d-fructose for 6 h, the space-time yield of d-mannose reached 27.2 g L-1 h(-1) with a maximum conversion ratio of 27%. Therefore, the d-mannose isomerase may be suitable for green production of d-mannose.

关键词： TiO2 nanoparticles   Oxidative damage   Biochemical toxicity   DNA damage   Eugenol   Wistar rats  

摘要： Titanium dioxide nanoparticles (TiO2 NPs) are widely used in food, edible dyes, and other commercial products. Human exposure to TiO2 NPs has raised concerns regarding their toxic potential. Various studies have evaluated the TiO2 NPs-induced toxicity, oxidative damage to the cellular components, and genotoxicity. In the present study, we examined whether co-treatment with the dietary antioxidant eugenol can attenuate or protect against TiO2 NPs-induced toxicity. We exposed the adult male Wistar rats to TiO2 NPs (150 mg/kg body weight) by intraperitoneal injection (i.p.) either alone or as co-treatment with eugenol (1-10 mg/kg body weight) once a day for 14 days. The untreated rats were supplied saline and served as control. Titanium (Ti) accumulation in various tissues was analyzed by inductively coupled plasma mass spectrometry. Serum levels of liver and kidney biomarkers and oxidative stress markers in the liver, kidney, and spleen were determined. A significant increase in hydrogen peroxide level confirmed that oxidative stress occurred in these tissues. TiO2 NPs induced oxidation of lipids, and decreased glutathione level and antioxidant enzyme activity in the kidney, liver, and spleen of treated rats. TiO2 NPs also increased the serum levels of alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, albumin, and total cholesterol and decreased the blood urea nitrogen, uric acid, and total bilirubin in serum, which indicates oxidative damage to the liver and kidney. In eugenol and TiO2 NPs co-treated rats, all these changes were mitigated. Single-cell gel electrophoresis (comet assay) of lymphocytes showed longer comet tail length in TiO2 NPs-treated groups, indicating DNA damage while tail length was reduced in eugenol and TiO2 NPs co-treated groups. Thus, it seems that eugenol can be used as a chemoprotective agent against TiO2 NPs-induced toxicity.

关键词： 2D L‐   COSY   MS fatigue   multiple sclerosis  

摘要： BACKGROUND AND PURPOSE Fatigue is the common symptom in patients with multiple sclerosis (MS), yet its pathophysiological mechanism is poorly understood. We investigated the metabolic changes in fatigue in a group of relapsing-remitting MS (RRMS) patients using MR two-dimensional localized correlated spectroscopy (2D L-COSY). METHODS Sixteen RRMS and 16 healthy controls were included in the study. Fatigue impact was assessed with the Modified Fatigue Impact Scale (MFIS). MR 2D L-COSY data were collected from the posterior cingulate cortex. Nonparametric statistical analysis was used to calculate the changes in creatine scaled metabolic ratios and their correlations with fatigue scores. RESULTS Compared to healthy controls, the RRMS group showed significantly higher fatigue and lower metabolic ratios for tyrosine, glutathione, homocarnosine (GSH+Hca), fucose-3, glutamine+glutamate (Glx), glycerophosphocholine (GPC), total choline, and N-acetylaspartate (NAA-2), while increased levels for isoleucine and glucose (P <= .05). Only GPC showed positive correlation with all fatigue domains (r = .537, P <= .05). On the other hand, Glx-upper, NAA-2, GSH+Hca, and fucose-3 showed negative correlations with all fatigue domains (r = -.345 to -.580, P <= .05). While tyrosine showed positive correlation with MFIS (r = .499, P <= .05), cognitive fatigue was negatively correlated with total GSH (r = -.530, P <= .05). No correlations were found between lesion load or brain volumes with fatigue score. CONCLUSIONS Our results suggest that fatigue in MS is strongly correlated with an imbalance in neurometabolites but not structural brain measurements.

关键词： Nonylphenol   Reactive oxygen species   Reproductive dysfunctions   Myricetin   Flavonol   Antioxidant  

摘要： Nonylphenol (NP) is an environmental contaminant, which induces testicular toxicity through oxidative stress. Myricetin (MYR) is a naturally occurring flavonol having powerful antioxidant activity. The current research was planned to examine the ameliorative role of MYR against NP-induced testicular damage. A total of 24 adult male Sprague-Dawley rats were randomly divided into 4 equivalent groups: control (0.1% DMSO), NP group (50 mg kg(-1)), NP + MYR group (50 mg kg(-1);100 mg kg(-1)), and MYR-treated group (100 mg kg(-1)). NP administration significantly (p < 0.05) decreased the activity of antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GSR), and protein content while significantly (p < 0.05) elevating the thiobarbituric acid reactive substances (TBARS) and reactive oxygen species (ROS) levels. Additionally, NP significantly (p < 0.05) reduced the sperm motility, gene expression of testicular steroidogenic enzymes (3 beta-HSD, 3 beta-hydroxysteroid dehydrogenase;17 beta-HSD, 17 beta-hydroxysteroid dehydrogenase;StAR, steroidogenic-acute regulatory protein), level of luteinizing hormone (LH), follicle-stimulating hormone (FSH), plasma testosterone, and daily sperm production (DSP). On the other hand, it raised the testicular cholesterol, dead sperms, and head, midpiece, and tail abnormalities along with abnormal histomorphometry. However, MYR remarkably abrogated NP-induced damages. In conclusion, the outcomes of the study suggest that MYR can effectively alleviate the NP-induced oxidative stress and testicular damages.

关键词： Arginine   Biochemical   Enamel   Fluoride   Varnish  

摘要： Objective: To examine the biochemical components of multi-species biofilm on the arginine (Arg)-sodium fluoride (NaF) varnish-treated enamel following bacterial pH-cycling. Methods: L-arginine (at 1%, 2%, & 4% w/v.) was incorporated in a 5% NaF varnish. The experimental and control groups were: 1%, 2%, 4% Arg-NaF, NaF, and no treatment. Enamel blocks were prepared, acid-etched, varnishtreated and then subjected to 72 h bacterial pH-cycling in an oral biofilm reactor. The organic (carbohydrates, proteins, amyloids, and eDNA) and inorganic components (calcium, inorganic phosphate, F) were assayed for the obtained biofilm suspensions. The biofilms were stained for exopolysaccharides (EPS)/bacteria and the respective proportions of live/dead bacteria was determined using confocal imaging. Results: The total carbohydrate content of the biofilm was the lowest for the 2% and 4% Arg-NaF (p < 0.05). Except for 2% Arg-NaF, the biofilm proteins for 4% Arg-NaF were significantly higher than the other groups (p < 0.05). The amyloids for Arg-NaF groups were significantly lower than the controls (p < 0.05). The eDNA for 4% Arg-NaF was significantly higher than the controls (p < 0.05). The 2% and 4% Arg-NaF-treated enamel had increased biofilm Pi and F compared to the NaF-treated enamel (p < 0.05). The proportion of biofilm EPS matrix to bacteria was significantly reduced in Arg-NaF groups compared to the controls (p < 0.05). The dead bacterial proportions of 4% Arg-NaF were significantly higher than the controls (p < 0.05). Conclusion: Higher concentrations (i.e. 2%/4%) of Arg in 5% NaF varnish have the potential to modulate the biochemical composition of the biofilm growing on the treated enamel.

关键词： Drosophila melanogaster   CG2139   Aspartate/glutamate carrier (AGC)   Aralar   Citrin   Phylogenetic footprint  

摘要： Background: In man two mitochondrial aspartate/glutamate carrier (AGC) isoforms, known as aralar and citrin, are required to accomplish several metabolic pathways. In order to fill the existing gap of knowledge in Drosophila melanogaster, we have studied aralar1 gene, orthologue of human AGC-encoding genes in this organism. Methods: The blastp algorithm and the "reciprocal best hit" approach have been used to identify the human orthologue of AGCs in Drosophilidae and non-Drosophilidae. Aralar1 proteins have been overexpressed in Escherichia coli and functionally reconstituted into liposomes for transport assays. Results: The transcriptional organization of aralar1 comprises six isoforms, three constitutively expressed (aralar1-RA, RD and RF), and the remaining three distributed during the development or in different tissues (aralar1-RB, RC and RE). Aralar1-PA and Aralar1-PE, representative of all isoforms, have been biochemically characterized. Recombinant Aralar1-PA and Aralar1-PE proteins share similar efficiency to exchange glutamate against aspartate, and same substrate affinities than the human isoforms. Interestingly, although Aralar1-PA and Aralar1-PE diverge only in their EF-hand 8, they greatly differ in their specific activities and substrate specificity. Conclusions: The tight regulation of aralar1 transcripts expression and the high request of aspartate and glutamate during early embryogenesis suggest a crucial role of Aralar1 in this Drosophila developmental stage. Furthermore, biochemical characterization and calcium sensitivity have identified Aralar1-PA and Aralar1-PE as the human aralar and citrin counterparts, respectively. General significance: The functional characterization of the fruit fly mitochondrial AGC transporter represents a crucial step toward a complete understanding of the metabolic events acting during early embryogenesis.

关键词： acetogens   CO2 fixation   Wood-Ljungdahl pathway   electron bifurcation   genetic tools   metabolic engineering   biofuel   hydrogen storage  

摘要： The review discusses the present-day data on the biochemistry, bioenergetics, and genetics of acetogens, as well as their biotechnological potential. Acetogens are anaerobic gram-positive bacteria capable of growth on gaseous substrates: CO2, CO, H-2. These bacteria have a characteristic biochemical pathway of CO2 reduction to acetyl-CoA, termed the reductive acetyl-CoA pathway or the Wood-Ljungdahl pathway. This is the only pathway of CO2 fixation coupled to energy storage. Due to their efficient non-photosynthetic CO2 fixation, acetogens may be used for production of chemicals and biofuel in the expected economy based on renewable energy and resources. The shortcomings of acetogens growing on gaseous substrates are low energy provision and a narrow spectrum of terminal metabolites, primarily acetic acid and ethanol with low amounts of butanol and butyric acid. Acetogens are capable of heterotrophic growth on such substrates as sugars, lactate, or alcohols. Mixotrophy, i.e., simultaneous utilization of different substrates by acetogens, is a promising approach to increasing the energy provision. Application of the methods of metabolic engineering is required both for successful coupling of different metabolic pathways and for broadening the range of synthesized products. Genetic tools for the transformation of genomes of acetogens have been considerably improved in recent years.

关键词： Piper betle   Essential oil   Constituents   Detoxifying enzymes   Ovipositional deterrence   Toxicity   Vector  

摘要： Housefly, Musca domestica L. is a pest of public health importance and is responsible for spreading diseases like typhoid, diarrhoea, plague etc. Indiscriminate reliance on synthetic insecticides has led to development of insecticide resistance and ill effect to humans and nontarget animals. This demands an alternative and safer pest control option. This study evaluates the biological effect of Piper betle L essential oil and its constituent eugenol, eugenol acetate, and beta-caryophyllene on the housefly. The major components present in P. betel EO were safrole (44.25%), eugenol (5.16%), beta-caryophyllene (5.98%), beta -selinene (5.93%), alpha-selinene (5.27%) and eugenol acetate (9.77%). Eugenol caused 4.5fold higher ovicidal activity (EC50 86.99 mu g/ml) than P. betle EO (EC50 390.37 mu g/ml). Eugenol caused fumigant toxicity to adults (LC50 88.38 mg/dm(3)). On contact toxicity by topical application, eugenol acetate, eugenol and beta-caryophyllene caused higher mortality to larval and adult stages than EO. FESEM (Field Emission Scanning Electron Microscope) images reveal that exposure to P. betle EO causes the shrinkage of the larval cuticle. Both EO and eugenol induced the detoxifying enzymes Carboxyl esterase (Car E) and Glutathione S - transferases (GST) in larvae and adults. EO and eugenol at 0.2% caused effective repellence and oviposition deterrence to M. domestica adults and this merits their use as alternative strategy to manage M. domestica.

关键词： Estrus synchronization   Fertility   Hair goat   Oxidative stress   Progesterone  

摘要： The aim of this study was to investigate the relationship between different estrus synchronization protocols, some fertility parameters and serum biochemical parameters including total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), thyroid stimulating hormone (TSH), estradiol (E2) and progesterone (P4) in Hair goats. The study was carried out on 150 female Hair goats during the breeding season. Goats were divided into three groups as control (n = 50), short-term (n = 50) and long-term (n = 50) groups. Control group did not receive any treatment, short-term group received intravaginal P4 (7 d) combined with GnRH (on days 0 and 9) and PGF2? (on day 7), and long-term group received intravaginal P4 (12 d) combined with pregnant mare?s serum gonadotropin (on day 12) and GnRH (on day 13). In control group, blood samples were collected at the beginning (first measurement) and 7th day (second measurement) of the study. In short-term and long-term groups, blood samples were collected at the time of sponge insertion (first measurement) and withdrawal (second measurement). Serum TAS, TOS, P4, E2, TSH levels were measured on all sampling days, and OSI was calculated. All the groups were observed for estrus behavior and those showing the signs of estrus were allowed for mating. Transrectal ultrasound examination was performed to diagnose pregnancy approximately 40 days after mating. The onset of estrus was earlier in short-term group compared to long-term group (P < 0.001). The estrus and pregnancy rates were significantly higher in short-term group compared to other groups (P < 0.05). At the time of first measurement, E2 level in short-term group and P4 level in long-term group were higher and lower than the other groups, respectively (P < 0.05). At the time of second measurement, TAS, TOS, OSI and E2 levels were significantly different in short-term group compared to control and long-term groups (P < 0.01). Additionally, P4 level in control