外源茉莉酸对大豆中异戊烯黄酮Glyceollins及其前体Glycinol累积的影响

以中黄13号大豆种子为材料,取生长8天的健康子叶,在其表面挖出约2×2mm的伤口,将50μl不同浓度的茉莉酸溶液和1mM的硝酸银溶液滴在伤口处,黑暗中(25℃)保温不同时间后取样,经甲醇提取,用高压液相色谱(HPLC)测定其中异戊烯化异黄酮glyceollins及其前体glycinol 的累积情况.结果显示,健康子叶中没有glyceollins和glycinol的累积,1mM硝酸银比茉莉酸具有更强的诱导glyceollins和glycinol累积的能力,glyceollins的累积与茉莉酸浓度呈负相关.在各种处理中,glyceollinⅠ、Ⅱ、Ⅲ所占比例分别为:50%～80%、10%～40%和10%～20%,但是glyceollin三种异构体的比例随保温时间的延长而有所变化,glyceollin Ⅰ比例逐渐下降,glyceollin Ⅱ所占比例逐渐升高,在1mM硝酸银处理的子叶中表现更为明显.     

Soil CO2 efflux and extractable organic carbon fractions under simulated precipitation events in a Mediterranean Dehesa

The magnitude of CO₂ efflux pulses after rewetting a dry soil is highly variable and the factors regulating these pulses are poorly understood. In this field experiment, we aimed to study the C dynamics after simulated summer rainstorms in a Mediterranean open holm oak woodland (dehesa). We hypothesized that because the herbaceous cover is mostly dead during the summer in this ecosystem, the short-term CO₂ efflux (SR) after rewetting could mainly be explained by different measurable soil C fractions: i) K₂SO₄-extracted soil C (EOC); ii) microbial biomass C (MBC); or iii) chloroform-fumigated extracted C (CFE). On both grazed and abandoned dehesa sites, we simulated three summer rain events at two-week intervals and we measured SR discontinuously in three plots under tree canopy and in another three plots in open grassland. In each plot, C fractions and water content were estimated before (2 h) and after (36 h) each irrigation event. Following rewettings, SR increased up to ten times compared with non-irrigated plots. The CFE actually increased after rewetting in the first two irrigations but not in the third event, suggesting that the capacity of the soil to release labile organic C from soil aggregates or litter was reduced after each irrigation event. Overall, the C released as CO₂ in the first 24 h was related to the CFE existing before rewetting, which may help to explain the spatial variability in SR. However, the explained variability decreased after each irrigation, suggesting a change to a less labile composition of the CFE fraction as a consequence of multiple drying-rewetting cycles.     

Potential Utilization of Mixolab for Quality Evaluation of Bread Wheat Genotypes

The aim of this study was to determine the possibility of using Mixolab to assess the quality of different wheat genotypes. Mixolab data were compared with various flour quality characteristics and bread volume. The samples were chosen to represent a wide range in terms of grain and rheological properties and baking quality. There are eight paramaters used to evaluate a Mixolab curve. C1 and C2 are related to protein quality, whereas C3, C4 and C5 are related to the starch characteristics. Slopes α, β, γ are the indicators of protein weakening, starching speed, and enzymatic degradation. There were significant correlations between two Mixolab parameters (Stability and C2) and Zeleny sedimentation and Alveograph W values (P < 0.01). Some of the Mixolab parameters (C3, C4, C5) were correlated with Alveograph G and P/L value (P < 0.01). Mixolab values are generally in agreement with Farinograph values. There were significant negative correlations between most of the Mixolab parameters (Stability, C2, C3, C4) and Farinograph softening degree. Stability and C2 parameters of Mixolab were also significantly correlated with Farinograph stability values (P < 0.01). The correlation between Mixolab stability and Farinograph stability was considerably high (r = 0.907, P < 0.001). The Mixolab parameters C3, C4, and C5 were significantly correlated with bread volume. Significant correlations were observed between slope α and Zeleny sedimentation (P < 0.05), Alveograph W (P < 0.01), Farinograph softening degree (P < 0.001), and stability (P < 0.001) values.     

Vitamin D2 formation from post-harvest UV-B treatment of mushrooms (Agaricus bisporus) and retention during storage

The objectives of this research were to study the effects of high intensity (0.5, 0.75, and 1.0 mW/cm (2)), dose (0.5, 1.0, and 1.5 J/cm (2)), and postharvest time (1 and 4 days) on the vitamin D 2 formation in Portabella mushrooms ( Agaricus bisporus) as a result of UV-B exposure, as well as the vitamin D 2 degradation in treated mushrooms during storage. Within each intensity application, dose had the largest effect where more exposure converted more vitamin D 2 from ergosterol. Similar dose across each intensity application resulted in similar vitamin D 2 concentration. Practical commercial production requires as short a treatment time as possible, and intensity was a major factor from this standpoint where the time it took to achieve a similar vitamin D 2 concentration for similar dose exposure was significantly reduced as intensity increased. By using an intensity of 1.0 mW/cm (2) at a dose of 0.5 J/cm (2), the concentration of vitamin D 2 produced was 3.83 microg/g dry solids of mushrooms in 8 min, whereas using an intensity of 0.5 mW/cm (2) at a dose of 0.5 J/cm (2), the concentration of vitamin D 2 produced was 3.75microg/g dry solids of mushrooms in 18 min. Also, postharvest time did not have a significant effect on vitamin D 2 formation in mushrooms that were treated 1 and 4 days after harvest. Vitamin D 2 degraded in treated mushrooms during storage by apparent first-order kinetics, where the degradation rate constant was 0.025 h (-1). The information provided in this study will help mushroom producers develop commercial-scale UV treatment processes to add value to their crop while improving consumer health.     

Urinary cortisol as an additional tool to assess the welfare of pregnant sows kept in two types of housing

The use of urinary cortisol (UC) as an additional tool to evaluate sows welfare was assessed in two experiments. In a preliminary methodological experiment, the kinetics of cortisol excretion in urine was studied during an Adreno Cortico Trophic Hormone (ACTH) challenge test in 10 pregnant sows. In a second experiment, 96 primiparous sows of an experimental unit were assigned to two different housing systems: 48 animals were housed in individual pens (IP) and 48 animals in collective pens (CP) with 6 animals per pen. UC was measured at the beginning and at the end of pregnancy and compared with other welfare indicators such as behaviour or skin damage. In both experiments, UC was measured using a high pressure liquid chromatography assay. In experiment 1, UC was constant on the day before injection of ACTH, with no variations related to circadian rhythm. It began to rise 2 h after the injection, peaked between 2 to 5 h after then returned to the basal concentration on the day after the injection. In experiment 2, UC concentrations were not different between CP- and IP-housed sows but they were higher in sows exhibiting the less stereotypies in comparison with sows exhibiting the most stereotypies. The results of this study suggest that UC is a good indicator of acute stress, more convenient than plasma cortisol measurement since it is a non-invasive method avoiding restraint or catheterisation of sows. They also suggest that UC could also give additional information on the assessment of chronic stress and improve the evaluation of animal welfare if used in conjunction with other welfare indicators.     

Alterins Produced by Oyster-Associated Pseudoalteromonas Are Antibacterial Cyclolipopeptides with LPS-Binding Activity

Discovery after discovery, host-associated microbiota reveal a growing list of positive effects on host homeostasis by contributing to host nutrition, improving hosts’ immune systems and protecting hosts against pathogens. In that context, a collection of oyster associated bacteria producing antibacterial compounds have been established to evaluate their role in non-host-derived immunity. Here, we described alterins; potent anti-Gram negative compounds produced by Pseudoalteromonas hCg-6 and hCg-42 isolated from different healthy oyster hemolymph. The strains hCg-6 and hCg-42 produce a set of at least seven antibacterial compounds, ranging from 926 to 982 Da structurally characterized as cyclolipopeptides (CLPs). Alterins share the same cationic heptapeptidic cycle connected via an amido bond to different hydrophobic hydrocarbon tails. Their MICs disclosed a potent antibacterial activity directed against Gram-negative bacteria including oyster and human pathogens that may confer a beneficial defense mechanism to the host but also represents an untapped source of new antibiotics. The alterins’ mechanisms of action have been deciphered: after binding to lipopolysaccharides (LPS), alterins provoke a membrane depolarization and permeabilization leading to bacterial lysis. As hCg-6 and hCg-42 produced a set of natural derivatives, the structure/activity relationship linked to the carbon tail is clarified. We showed that the hydrocarbon tail determines the LPS-binding properties of alterins and consequently their antibacterial activities. Its length and saturation seem to play a major role in this interaction.     

外源茉莉酸对大豆异黄酮的影响

摘下生长8天的大豆子叶,在不同浓度茉莉酸溶液中浸泡一定时间,用甲醇提取大豆异黄酮,经高压液相色谱(HPLC)测定,研究子叶表面伤口、浸泡时间以及茉莉酸浓度对大豆异黄酮的影响.结果显示:在对照组(0.1%乙醇),子叶表面的伤口不影响异黄酮的分配比例;而用茉莉酸浸泡组,健康子叶中几乎不存在游离型的大豆甙元和染料木黄酮;丙二酰大豆甙和丙二酰染料木甙所占比例随着浸泡时间的延长而下降,大豆甙元和染料木黄酮所占比例随浸泡时间的延长而增加,大豆甙和染料木甙所占比例不随浸泡时间而变化;20μM茉莉酸溶液浸泡的子叶中异黄酮总量最低.