根际温度对黄瓜幼苗生长及生理生化指标的影响

采用营养液栽培法,以‘春秋王2号’黄瓜为实验材料,研究了4个根际温度梯度处理(20℃、25℃、30℃、35℃)对其幼苗生长,地上部、地下部生理生化指标的影响,探讨根际温度对黄瓜幼苗生长的影响机理。结果显示:(1)黄瓜幼苗的株高、茎粗、叶面积和地上地下生物量在25℃处理下都明显大于其他3个处理,而在35℃处理下均显著降低。(2)20℃、25℃处理下,黄瓜幼苗叶片的净光合速率(Pn)均较大,此时其叶片与根系中的淀粉、蔗糖、总糖含量较高且明显高于30℃处理,35℃根际温度处理下叶片Pn严重下降。(3)根际30℃、35℃高温使得黄瓜幼苗叶片和根系中的POD活性升高,CAT活性降低;而叶片中SOD、APX活性均随根际温度的升高而增大,根系中则表现出了逐渐下降趋势。(4)叶片和根系的电解质渗漏率、丙二醛(MDA)含量在25℃下最低,而在35℃处理下最高;叶片中脯氨酸及可溶性蛋白含量在35℃处理下最高,但此时根系中含量显示最低。研究表明,4个根际温度中,25℃最适合黄瓜幼苗的生长,35℃高温直接作用部位(根系)的2种主要渗透调节物质脯氨酸及可溶性蛋白含量下降,此时叶片和根系中抗氧化酶活性的变化使得细胞膜受到了明显的过氧化伤害,根系受伤害程度加重,从而抑制了植株整体的生长。     

The hydrolysate of barley straw containing inhibitors can be used to produce cephalosporin C by solvent extraction using ethyl acetate

When the solvent extraction of the hydrolysate from barley straw was performed using ethyl acetate (EA), the logarithm of the partition coefficient (log P) of the phenols and furans for EA was found to be more than 1.00, which means that more than 90% of the inhibitors were removed from the hydrolysate layer. Cephalosporin C (CPC) was produced from the hydrolysate of dilute acid pretreatment (DAP) by Acremonium chrysogenum M35. A. chrysogenum M35 was cultured using the hydrolysate and the amount of CPC produced was found to be 10.35 g/L at 144 h. Also, the dry cell weight was about 101.5 g/L at 120 h. The utilization of the hydrolysate for CPC production was effective and the solvent extraction method for the removal of inhibitory substances could contribute to the biorefinery process.     

Activation of farnesoid X receptor attenuates hepatic injury in a murine model of alcoholic liver disease

Alcoholic liver disease (ALD) is a common cause of advanced liver disease, and considered as a major risk factor of morbidity and mortality worldwide. Hepatic cholestasis is a pathophysiological feature observed in all stages of ALD. The farnesoid X receptor (FXR) is a member of the nuclear hormone receptor superfamily, and plays an essential role in the regulation of bile acid, lipid and glucose homeostasis. However, the role of FXR in the pathogenesis and progression of ALD remains largely unknown. Mice were fed Lieber-DeCarli ethanol diet or an isocaloric control diet. We used a specific agonist of FXR WAY-362450 to study the effect of pharmacological activation of FXR in alcoholic liver disease. In this study, we demonstrated that FXR activity was impaired by chronic ethanol ingestion in a murine model of ALD. Activation of FXR by specific agonist WAY-362450 protected mice from the development of ALD. We also found that WAY-362450 treatment rescued FXR activity, suppressed ethanol-induced Cyp2e1 up-regulation and attenuated oxidative stress in liver. Our results highlight a key role of FXR in the modulation of ALD development, and propose specific FXR agonists for the treatment of ALD patients.     

The cardioprotective effects elicited by p66 ablation demonstrate the crucial role of mitochondrial ROS formation in ischemia/reperfusion injury

Although a major contribution to myocardial ischemia-reperfusion (I/R) injury is suggested to be provided by formation of reactive oxygen species (ROS) within mitochondria, sites and mechanisms are far from being elucidated. Besides a dysfunctional respiratory chain, other mitochondrial components, such as monoamine oxidase and p66^Shc, might be involved in oxidative stress. In particular, p66^Shc has been shown to catalyze the formation of H₂O₂.The relationship among p66^Shc, ROS production and cardiac damage was investigated by comparing hearts from p66^Shc knockout mice (p66^Shc−/−) and wild-type (WT) littermates. Perfused hearts were subjected to 40 min of global ischemia followed by 15 min of reperfusion. Hearts devoid of p66^Shc were significantly protected from I/R insult as shown by (i) reduced release of lactate dehydrogenase in the coronary effluent (25.7 ± 7.49% in p66^Shc−/− vs. 39.58 ± 5.17% in WT); (ii) decreased oxidative stress as shown by a 63% decrease in malondialdehyde formation and 40 ± 8% decrease in tropomyosin oxidation. The degree of protection was independent of aging.The cardioprotective efficacy associated with p66^Shc ablation was comparable with that afforded by other antioxidant interventions and could not be increased by antioxidant co-administration suggesting that p66^Shc is downstream of other pathways involved in ROS formation. In addition, the absence of p66^Shc did not affect the protection afforded by ischemic preconditioning.In conclusion, the absence of p66^Shc reduces the susceptibility to reperfusion injury by preventing oxidative stress. The present findings provide solid and direct evidence that mitochondrial ROS formation catalyzed by p66^Shc is causally related to reperfusion damage.     

Effect of the addition of inert cellulose substrates to grape must on Saccharomyces cerevisiae diversity and the evolution of alcoholic fermentation

AIMS: To study the addition of cellulose-based adjuvant as a resource to offset the negative effects produced by grape juice clarification during alcoholic fermentations. METHODS AND RESULTS: The effect of the addition of two kinds of inert cellulose substrates in white wine vinification was investigated in two different musts. In one of these musts, stuck fermentations were detected. One of the types of cellulose examined had a fining effect, which caused a decrease in the number of viable yeasts in the medium and altered the distribution and frequency of the clones, which performed the fermentation. The other cellulose substrate made the medium cloudier but did not alter the distribution of yeasts in comparison with the control. CONCLUSIONS: The behaviour of the inert cellulose substrates on vinification depends on its physical characteristics and its capacity for making the must cloudy. SIGNIFICANCE AND IMPACT OF THE STUDY: The addition of inert cellulose substrates in white wine vinification improves the fermentation process and the quality of wines obtained. This effect is more noticeable in difficult fermentations. One variety of cellulose showed an inhibitory effect on Torulaspora delbrueckii yeasts.     

Production of Antimicrobial Substances by Bacteria Isolated from Fermented Table Olives

Summary The production of antimicrobial substances was studied among 195 bacterial isolates from retail table olives. A total 86 isolates tested positive, and they clustered in 10 groups according to their inhibitory spectra. Many isolates (38.37%) produced strong inhibition against all bacteria tested (Listeria innocua, Lactococcus lactis, Bacillus cereus, B. megaterium, Staphylococcus aureus, Micrococcus luteus, Enterococcus faecalis, and Escherichia coli). The selected bacterial isolates were Gram-positive bacteria with rod morphology (62.67%), short rods (26.65%) or cocci (10.67%). Isolates producing antimicrobial substances may be useful as starters to enhance control of table olive fermentation and improve the safety of retail table olives.     

The oxidative damage of plasmid DNA by ascorbic acid derivatives in vitro: the first research on the relationship between the structure of ascorbic acid and the oxidative damage of plasmid DNA

To study the structure-function relationship of the oxidative-damage effect of ascorbic acid, we have focused on the interaction between plasmid DNA pUC19 and a series of ascorbic acid derivatives modified on different OH groups in the presence of transition metal ions. Some ascorbic acid derivatives can selectively cleave plasmid DNA from Form I to Form II in the presence of low concentration of Cu2+ just like ascorbic acid itself, while other derivatives oxidatively damage plasmid DNA slightly. We found that those derivatives with unattached 2-OH and 3-OH groups retain the ability to cleave the plasmid DNA. The derivatives that have been methylated on 2-OH or 3-OH can only cleave plasmid DNA softly, and those derivatives that have been protected on both 2-OH and 3-OH can hardly exert an oxidative damage on plasmid DNA under the same condition. Form these results, we can draw the conclusion that 2-OH and 3-OH groups of the ascorbic acid molecule contribute most to this biological activity.     

Changes in blood plasma volume in rats during ontogenesis

The dynamics of blood plasma volume were studied for the first time in rats during ontogenesis. The significance of blood plasma volume is estimated in the transport of physiologically active substances to cells and target organs during development. The blood plasma volume was measured in male and female rats during embryogenesis on day 18 (E18), perinatal development on E21 and day 3 of postnatal development (P3), and postnatal development on P15 and P30. Blood plasma volume was measured using Evans Blue dye method. Body mass was determined in the same animals and correlation was estimated between the blood plasma volume and body mass. The plasma volume increased 1.9-fold from E18 to E21, 1.4-fold from E21 to P3, 2.1-fold from P3 to P15, and 3.4-fold from P15 to P30. The body mass increased 5-fold from E18 to E21, 2-fold from E21 to P3, 2.3-fold from P3 to P15, and 3.2-fold from P15 to P30. The ratio of blood plasma to body mass was the highest on E18 (19%) and decreased twice by E21. This index varied from 5.4 to 4.8% during postnatal development. No sex-related differences in these indices were found in rats. The results obtained make it possible to determine the total content of physiologically active substances on the basis of their plasma concentration and, thereby, estimate the efficiency of secretory organs.     

香蕉果实成熟软化过程中细胞壁物质的变化

系统研究了香蕉果实软化过程中细胞壁物质―醇不溶性固形物(AIS)以及3种不同性质的果胶物质:水溶性果胶(WSP)、酸溶性果胶(HP)和碱溶性果胶(OHP)含量的变化。结果表明:随果实的成熟软化,AIS的含量不断降低,且在呼吸跃变时急剧降低;WSP的含量不断增加,HP和OHP的含量不断减少,且均表现出在早期变化量少,在果实硬度迅速降低时变化明显。该研究进一步证明细胞壁物质的变化是导致香蕉果实软化的主要原因。