苹果多酚-壳寡糖微胶囊的制备表征及释放特性

为了有效提高未熟苹果多酚（apple polyphenols,APP）和壳寡糖（chitooligosaccharides,COS）多功能协调效应,该研究采用喷雾干燥法研制未成熟的苹果多酚-壳寡糖微胶囊（apple polyphenols-chitooligosaccharides microcapsule,APCM）,并测定了APCM的微胶囊粒度和分布,以及结构表征,并评价了模拟胃肠道消化模型对总多酚（total phenolic content,TPC）释放和健康益处功能的影响。激光粒度分析结果表明,APCM的平均粒径为32.98μm。跨度值最小为1.19,这意味着APCM比COS和APP更均匀、颗粒度更小。APP在1 237和1 194cm-1处观察到了清晰的峰形,在APCM中同一位置处未观察到。但是,APCM与APP具有相似的吸收带,这意味着APP与COS也可能通过范德华力和分子间氢键的方式形成APCM。模拟胃肠消化模型结果表明,APCM中多酚的释放发生在60 min以内。在模拟胃液消化系统（simulated gastric fluid,SGF）处理中,APCM释放的TPC从25.6%到76.5%不等,而在模拟肠液消化系统（simulated intestinal fluid,SIF）持续处理中,TPC释放量达到31.3%到97.6%。体外抗氧化活性和活性氧（reactive oxygen species,ROS）清除活性结果表明,相比与APP和COS,APCM对抗氧化能力指数、清除DPPH自由基、铁离子还原抗氧化力、?OH清除活性、O2?-清除活性和H2O2清除活性表现出更出色的清除自由基活性。此外,与APP或COS相比,APCM不仅表现出更高的糖还原酶抑制活性（P<0.05）,而且具有更好的血管紧张素I转换酶（Angiotensin I converting enzyme,ACE）抑制活性（P<0.05）。结果表明,APCM今后可在功能性食品或药物领域更大的研发潜力。     

Insecticidal activity and mode of action of 2,4‐diaminopyrimidines

Three 2,4‐diaminopyrimidines were tested against several insect species. They were active against lepidopteran pests with LC₅₀ values <3 mg liter⁻¹ for most species tested. They were also active against two‐spotted spider mite, Tetranychus urticae, (LC₅₀ 10–40 mg liter⁻¹). Folinate, but not hypoxanthine or thymidine was found to be an effective rescue agent, requiring a concentration of 100 mg liter⁻¹ diet to rescue half of the intoxicated larvae. The results confirm dihydrofolate reductase to be the site of action for these insecticides and are consistent with the mode of action of folinate rescue in mammals. © 2000 Society of Chemical Industry     

光强对生菜硝酸盐累积的影响

以意大利耐抽苔生菜为试验材料,研究了5个梯度(75,150,225,450,550mol/s·m2)光照强度处理对其叶绿素相对含量、干重等生理指标和硝酸盐累积的影响。结果表明,光照强度显著的影响植株生长及各测定指标。叶绿素含量与光强呈正相关;地上部分和地下部分硝酸盐的累积与光强呈负相关;光合速率的日变化出现第一个波峰的时间要比田间作物滞后;分析各指标后表明最适合生菜生长的光照强度为450mol/(s·m2),达到了低硝酸盐的累积与生长品质的统一。     

氮钾锌配施对烟草超氧化物歧化酶和硝酸还原酶活性及根系活力的影响

采用盆栽试验,研究了氮钾锌配施对烟草超氧化物歧化酶（SOD）活性、硝酸还原酶（NR）活性以及根系活力的影响,结果表明：随着氮、钾、锌用量的增加,超氧化物歧化酶（SOD）活性、硝酸还原酶心㈧活性以及根系活力呈现先增长后降低的趋势,其中旺长期受影响最大,以处理组合N1K1Zn1（氮150mg／kg,钾450mg／kg,锌80mg／kg）的效果最优,由此可见,适当的氮钾锌配施能提高烟草超氧化物歧化酶活性、硝酸还原酶活性以及根系活力。     

小麦新鲜根系铁氰化钾还原酶与氢、钾跨膜运输的关系

为研究麦根质膜氧化还原反应与钾离子吸收的关系,比较不同基因型小麦吸钾差异,以水培和短期生物吸收试验方法,检测到小麦根系铁氰化钾还原酶的存在,而且不同品种铁氰化钾还原酶还原活性不同。反应液中由于根系内外质子和钾离子的迁移,加与不加铁氰化钾,不同品种根系都引起了溶液pH的改变,但外部电子受体Fe(CN)63-的存在即铁氰化钾还原酶底物的存在加强了溶液pH改变（更多为降低）的程度。铁氰化钾还原也明显影响了根系钾离子的吸收或外排动态,但不同品种影响不同。小麦根细胞膜氧化还原系统明显影响质子和钾离子的跨膜运输,不同品种影响不同。     

盐胁迫下硝态氮对囊果碱蓬根系发育和氮吸收的影响

The effiects of NaCl salinity and NO₃^- on growth, root morphology, and nitrogen uptake of a halophyte Suaeda physophora were evaluated in a factorial experiment with four concentrations of NaCl (1, 150, 300, and 450 mmol L^-1) and three NO₃^- levels (0.05, 5, and 10 mmol L^-1) in solution culture for 30 d. Addition of NO₃^- at 10 mmol L^-1 significantly improved the shoot (P < 0.001) and root (P < 0.001) growth and the promotive effect of NO₃^- was more pronounced on root dry weight despite the high NaCl concentration in the culture solution, leading to a significant increase in the root:shoot ratio (P < 0.01). Lateral root length, but not primary root length, considerably increased with increasing NaCl salinity and NO₃^- levels (P < 0.001), implying that Na⁺ and NO₃^- in the culture solution simultaneously stimulated lateral root growth. Concentrations of Na⁺ in plant tissues were also significantly increased by higher NaCl treatments (P < 0.001). At 10 mmol L^-1 NO₃^- , the concentrations of NO₃^- and total nitrogen and nitrate reductase activities in the roots were remarkably reduced by increasing salinity (P < 0.001), but were unaffected in the shoots. The results indicated that the fine lateral root development and effective nitrogen uptake of the shoots might contribute to high salt tolerance of S. physophora under adequate NO₃^- supply.     

施肥对土壤及黄瓜中稳定性氮同位素丰度的影响

研究不同肥料配施对土壤、黄瓜及其叶片中稳定性氮同位素丰度(1δ5N‰)及硝酸盐和硝酸还原酶活性的影响。结果表明,随着配施有机肥比例的降低,黄瓜中1δ5N呈现先低后高再低的趋势;各处理单施化肥初期时黄瓜中1δ5N与有机肥60%和40%配施处理间差异显著(P0.05),中期时与有机肥60%、40%配施处理及对照间的差异显著(P0.05),末期时与有机肥60%配施处理间有差异(P0.05),与其他不同配施时差异不显著(P0.05);相同处理的不同采摘时期黄瓜中1δ5N差异不显著(P0.05)。不同处理时叶片与黄瓜间的1δ5N呈正相关(r=0.9836),其1δ5N主要受不同肥料配施处理的影响。随着有机肥比例的降低,黄瓜中硝酸盐含量逐渐降低,与黄瓜中1δ5N间的线性相关性差(r=0.6568);而叶片中硝酸还原酶活性逐渐提高,其中对照处理、100%、80%和60%有机肥处理时与叶片中δ15N丰度呈正相关(r=0.9187);60%、40%、20%有机肥和100%化肥处理时与叶片中1δ5N呈负相关(r=-0.9773)。总体来看,可以初步利用1δ5N作为标记来区分有机肥和化肥种植的黄瓜,但需要进一步研究1δ5N在作物中的分馏和分布规律。     

Functional stability of the nitrate-reducing community in grassland soils towards high nitrate supply

To study the effects of short-term fluctuation of nitrate concentrations on the nitrate-reducing community, repacked soil cores were amended with 0, 100 and soil and incubated for 3, 7 and 14 days, respectively. The nitrate reductase activity was determined in a laboratory-based enzyme assay. In parallel, the community structure of nitrate-reducing microorganisms was characterised by RFLP-PCR using the functional gene narG, which encodes the catalytic site of the membrane-bound nitrate reductase. The community structure remained constant over the experimental period indicating that this functional community is characterised by a high resistance towards fluctuating nitrate concentrations. Decreases in nitrate concentration as well as increase in pH values indicated a very active nitrate-reducing community under nitrate addition. Surprisingly, inhibition of nitrite reductase by 2,4-dinitrophenol, which is a precondition for the measurement of nitrate reductase activity, could not be achieved in the treatment despite increased concentrations of the inhibitor. However, comparison of the nitrate reductase in the control and the treatment showed a significant increase in the latter at day 3. No further differences were observed at days 7 and 14, which suggests a high resilience of the nitrate reductase activity.     

The stereoisomerism of second generation anticoagulant rodenticides: a way to improve this class of molecules to meet the requirements of society?

Second generation anticoagulant rodenticides (SGAR) are generally highly efficient for rodent management even towards warfarin‐resistant rodents. Nevertheless, because of their long tissue‐persistence, they are very associated with non‐target exposure of wildlife and have been identified as ‘Candidates for Substitution’ by the European Union's competent authority. A promising way to reduce ecotoxicity issues associated to SGAR could be the improvement of SGAR based on their stereoisomery, and due to this improvement, positioning about SGAR might be reconsidered. © 2018 Society of Chemical Industry