Effects of Monoterpenoids, Acting Alone or in Pairs, on Seed Germination and Subsequent Seedling Growth

We compared the potential allelopathic activity of 47 monoterpe- noids of different chemical groups, by estimating their effect on seed germination and subsequent growth of Lactuca sativa seedlings. Apart from individual compounds, eleven pairs at different proportions were also tested. As a group, the hydrocarbons, except for (+)-3-carene, were the least inhibitory. Of the oxygenated compounds, the least inhibitory were the acetates; whenever the free hydroxyl group of an alcohol turned into a carboxyl group, the activity of the resulting ester was markedly lower (against both germination and seedling growth). Twenty-four compounds were extremely active against seedling growth (inhibiting it by more than 85%), but only five against seed germination. The compounds that were most active against both processes belonged to the groups of ketones and alcohols; they were terpinen-4-ol, dihydrocarvone, and two carvone stereoisomers. We used a model to investigate whether compounds acted independently when applied in pairs. The combined effect varied. In half of the cases, it followed the pattern expected under the assumption of independence; in the rest, either synergistic or antagonistic interactions were found in both germination and elongation. However, even in cases of synergistic interactions, the level of inhibition was not comparable to that of a single extremely active compound, unless such a compound already participated in the combination. The specific structural factors that operate and determine the activity of monoterpenoids still remain rather obscure. The same holds true for the combined effect; its character cannot in general be predicted on the basis of individual compounds acting alone.     

Soil and leaf nutrient interactions following application of calcium silicate slag to sugarcane

In certain areas of the Everglades Agricultural Area, plant and ratoon sugarcane (Saccharum L.) yields are increased by application of Si from calcium silicate slag. The greatest yield responses are obtained in the plant crop the first year after application of slag and when plant uptake of Si is increased. Magnesium deficiencies have been reported after slag application. The objective of this study was to quantify interactions of soil and leaf nutrients on sugarcane grown on a Terra Ceia muck (Euic, hyperthermic Typic Medisaprist) that had previously received calcium silicate slag. Slag was applied at five rates, and yields were evaluated from plant, first-ratoon, and second-ratoon (stubble) crops at two locations. Soil and leaf from each crop were sampled for nutrient analysis and the results were used to interpret the yield data. Although slag increased cane yield by as much as 39% and sugar yield by 50%, for each 100 mg L^–1 drop in extractable soil Mg, cane yields declined by 5.3 Mg ha^–1 and sugar yields by 0.9 Mg ha^–1. At leaf Si concentrations exceeding 10 g kg^–1, optimum cane and sugar yields were observed, while leaf Mg concentrations approached critical leaf concentrations below 1.5 g kg^–1. Estimates of total leaf nutrient uptake during each crop indicated that uptake of Mg did not meet nutrient demands at high biomass production. Nutrient antagonism between Si and Mg is suggested. Low soil Mg may contribute to the marked crop responses to slag and for the decline in stubble production. Application of a magnesium fertilizer may be necessary to maintain high nutrient availability.Contribution from the University of Florida, Institute of Food and Agricultural Sciences. Florida Agric. Exp. Stn., Journal Series no. R-00859.     

Out of Context: NMDA Receptor Antagonism in the Avian 'Prefrontal Cortex' Impairs Context Processing in a Conditional Discrimination Task.

Processing of context information is implicated in prefrontal functions as response selection or attention. N-methyl-D-aspartate (NMDA) receptors in the mammalian prefrontal cortex (PFC) and in the nidopallium caudolaterale (NCL) of birds, the avian functional equivalent of the PFC, are involved in learning, which also requires processing of context. The authors investigated the role of NMDA receptors in the pigeon (Columba livia) NCL for context processing and response selection in a simultaneous-matching-to-sample task with 2 trial types, requiring either processing of context information, delivered by a conditional stimulus (context dependent), or only recall of a stimulus-response association (fixed response). The competitive NMDA antagonist DL-2-amino-5-phosphonovaleric acid impaired performance only in context-dependent trials. Therefore, NMDA receptors in the avian PFC participate in response selection requiring context processing rather than in response selection per se. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparative Cytotoxicity of Artemisinin and Cisplatin and Their Interactions with Chlorogenic Acids in MCF7 Breast Cancer Cells

In parts of Africa and Asia, self‐medication with a hot water infusion of Artemisia annua (Artemisia tea) is a common practice for a number of ailments including malaria and cancer. In our earlier work, such an extract showed better potency than artemisinin alone against both chloroquine‐sensitive and ‐resistant parasites. In this study, in vitro tests of the infusion in MCF7 cells showed high IC₅₀ values (>200 μM ). The combination of artemisinin and 3‐caffeoylquinic acid (3CA), two major components in the extract, was strongly antagonistic and gave a near total loss of cytotoxicity for artemisinin. We observed that the interaction of 3CAs with another cytotoxic compound, cisplatin, showed potentiation of activity by 2.5‐fold. The chelation of cellular iron by 3CA is hypothesized as a possible explanation for the loss of artemisinin activity.     

纳美芬对腹腔镜胆囊切除术患者术后呼吸抑制的拮抗作用

目的：探讨纳美芬对腹腔镜胆囊切除术患者术后呼吸抑制的拮抗作用。方法将110例行腹腔镜胆囊切除术患者根据术后使用拮抗药物的不同分为 A 组和 B 组,每组55例。A 组在手术结束后5 min 静脉推注盐酸纳美芬注射液0．25μg·kg－1,B 组在手术结束后5 min 静脉推注纳洛酮1μg·kg－1。观察2组给予拮抗药前,给予拮抗药后2、10 min,拔管后5 min 收缩压（SBP）、舒张压（DBP）、心率（HR）、平均动脉压（MAP）和血氧饱和度（SpO2）的变化以及给予拮抗药后10 min 呼吸恢复率、拔管时间和不良反应（包括躁动、高血压、心动过速、过敏反应和肺水肿）的情况,并对2组拔管后5 min 意识状况及拔管后30 min 镇痛情况进行评分（分别采用 Ramsay 和VAS 评分）。结果A 组拔管时间为（5．4±0．3）min,B 组拔管时间为（6．1±0．4）min,2组比较差异无统计学意义（P ＞0．05）。2组给予拮抗药后2、10 min 和拔管后5 min 时 SBP、DBP、SpO2比较差异均无统计学意义（均 P ＞0．05）,A 组给予拮抗药后10 min 呼吸恢复率明显高于 B 组（P ＜0．05）,2组拔管后30 min VAS 和拔管后5 min Ramsay 得分比较差异均无统计学意义（均 P ＞0．05）。A 组恶心、躁动、转氨酶升高1例（1．8％）,B 组恶心、躁动、转氨酶升高2例（3．6％）,2组比较差异无统计学意义（P ＞0．05）。结论纳美芬可安全、有效地拮抗腹腔镜胆囊切除术患者术后引起的呼吸抑制,且患者呼吸恢复率优于纳洛酮。     

乳酸菌的生物拮抗作用

论述了乳酸菌的生物拮抗作用,包括对致病菌和乳酸菌之间的拮抗。并简要论述了产生拮抗作用的可能因素或机理,为乳酸菌进一步开发提供一种理论依据。     

酸菜腌制及保藏方法的研究进展

酸菜的乳酸菌发酵作用、蛋白质分解作用以及风味形成过程赋予了产品特有的风味,因而受到越来越多人的喜爱。但是酸菜生产的季节性以及人们常年性需求之间的矛盾使得酸菜能够长期保藏显得尤为重要。但是酸菜在保藏过程中由于生物的、物理的以及化学作用使其容易腐败变质。为此,本文通过文献调研,分别从酸菜自身,外部工艺条件等角度出发,较全面地阐述了有效地延长酸菜保质期的方法,特别地强调了生物防腐剂以及拮抗微生物的应用前景。本文内容从食品安全以及市场化前景角度展望了未来酸菜腌制及保藏的发展方向,为相关领域的研究提供思路。     

Interaction intimacy organizes networks of antagonistic interactions in different ways

Interaction intimacy, the degree of biological integration between interacting individuals, shapes the ecology and evolution of species interactions. A major question in ecology is whether interaction intimacy also shapes the way interactions are organized within communities. We combined analyses of network structure and food web models to test the role of interaction intimacy in determining patterns of antagonistic interactions, such as host–parasite, predator–prey and plant–herbivore interactions. Networks describing interactions with low intimacy were more connected, more nested and less modular than high-intimacy networks. Moreover, the performance of the models differed across networks with different levels of intimacy. All models reproduced well low-intimacy networks, whereas the more elaborate models were also capable of reproducing networks depicting interactions with higher levels of intimacy. Our results indicate the key role of interaction intimacy in organizing antagonisms, suggesting that greater interaction intimacy might be associated with greater complexity in the assembly rules shaping ecological networks.     

Efficacy of six grain protectants applied alone or in combination against three species of coleoptera

Laboratory experiments were carried out to establish whether there were synergistic or antagonistic interactions in combination treatments of certain grain protectants. Six protectants were applied alone, or in combination, against Rhyzopertha dominica (F.) in stored maize and wheat, and Sitophilus oryzae (L.) and Tribolium castaneum (Herbst) in stored wheat. There were four organophosphorus (OP) insecticides (fenitrothion, chlorpyrifos-methyl, pirimiphos-methyl and methacrifos), one juvenile hormone analogue (methoprene) and one synergised pyrethroid (deltamethrin+piperonyl butoxide); and combination treatments consisted of either methoprene or synergised deltamethrin plus an OP insecticide. Based on the levels of control of adult progeny and periods of protection, there were no interactions between protectants. The results show that there is no need to alter field application rates to compensate for antagonism or to take advantage of synergism. They also support the view that application rates for combination treatments can be estimated from experiments on individual protectants using target species or strains.