甘薯叶的挥发性化学成分的研究

本文对甘薯(Ipomoea batatas Lam.)叶中挥发性化学成分采用气相色谱/质谱法进行了定性、定量分析,从92个色谱峰中鉴定出17个化合物,含量占总组成的95.09％,主要成分为棕榈酸(占47.62％)相亚麻油酸(占16.62％)。     

Transport of mercury by the Katun river,West Siberia

Some results of a 2-year study of mercury pollution of the Katun river (Siberia) are summarised. Measurements of water flow, sediment transport and mercury concentrations were made and used to calculate the amount of mercury transported by the river. The distribution of transport between water phase and suspended material is calculated. It is concluded that suspended sediments play the main role in this process. The significance of different fractions of suspended sediment is also discussed.     

Aspects of modelling sediment transport and night conditions in Lake Marken

In lake Marken (Markermeer), a shallow lake in the Netherlands, sediment transport and suspended solids concentration are dominated by wind induced resuspension of sediment. The suspended solids concentration in the lake determines the attenuation of light. A 2-dimensional sediment transport model, STRESS-2d, was used to estimate the special distribution of the silt content for periods with different wind conditions. The model was calibrated using measured values of the fall velocity distributions of sediment, freshly deposited material and suspended solids. The specific light attenuation coefficient of the various sediment classes was also measured and used in the light attenuation model, CLEAR, together with simulation results from the STRESS-2d model, to simulate the light attenuation variations in time and space. By comparison of the simulation results for different scenarios, the influence of regional planning features on the sediment balance and the light attenuation can quantified. A provisional example of this method is presented.     

Wild-induced resuspension in a small shallow lake

Resuspension of inorganic sediments in a very shallow Swedish lake is studied using settling sediment traps and measurements of suspended matter. Theoretical aspects of resuspension dynamics is discussed emphasizing special shallow lake aspects. Bottom shear stress distribution is computed for different wind conditions.     

Selection by parasitoid females among closely related hosts based on volatiles: Identifying relevant chemical cues

Parasitoid fitness is influenced by the ability to overcome host defense strategies and by the ability of parasitoid females to select high‐quality host individuals. When females are unable to differentiate among hosts, their fitness will decrease with an increasing abundance of resistant hosts. To understand the effect of mixed host populations on female fitness, it is therefore necessary to investigate the ability of female parasitoids to select among hosts. Here, we used behavioral assays, headspace volatile collection, and electrophysiology to study the ability of Asecodes parviclava to use olfactory cues to select between a susceptible host (Galerucella calmariensis) and a resistant host (Galerucella pusilla) from a distance. Our studies show that parasitoid females have the capacity to distinguish the two hosts and that the selection behavior is acquired through experiences during earlier life stages. Further, we identified two volatiles (α‐terpinolene and [E]‐β‐ocimene) which amounts differ between the two plant–herbivore systems and that caused behavioral and electrophysiological responses. The consequence of this selection behavior is that females have the capacity to avoid laying eggs in G. pusilla, where the egg mortality is higher due to much stronger immune responses toward A. parviclava than in larvae of G. calmariensis.     

Modification of chrysanthemum odour and taste with chrysanthemol synthase induces strong dual resistance against cotton aphids

Aphids are pests of chrysanthemum that employ plant volatiles to select host plants and ingest cell contents to probe host quality before engaging in prolonged feeding and reproduction. Changes in volatile and nonvolatile metabolite profiles can disrupt aphid–plant interactions and provide new methods of pest control. Chrysanthemol synthase (CHS) from Tanacetum cinerariifolium represents the first committed step in the biosynthesis of pyrethrin ester insecticides, but no biological role for the chrysanthemol product alone has yet been documented. In this study, the TcCHS gene was over‐expressed in Chrysanthemum morifolium and resulted in both the emission of volatile chrysanthemol (ca. 47 pmol/h/gFW) and accumulation of a chrysanthemol glycoside derivative, identified by NMR as chrysanthemyl‐6‐O‐malonyl‐β‐D‐glucopyranoside (ca. 1.1 mM), with no detrimental phenotypic effects. Dual‐choice assays separately assaying these compounds in pure form and as part of the headspace and extract demonstrated independent bioactivity of both components against the cotton aphid (Aphis gossypii). Performance assays showed that the TcCHS plants significantly reduced aphid reproduction, consistent with disturbance of aphid probing activities on these plants as revealed by electropenetrogram (EPG) studies. In open‐field trials, aphid population development was very strongly impaired demonstrating the robustness and high impact of the trait. The results suggest that expression of the TcCHS gene induces a dual defence system, with both repellence by chrysanthemol odour and deterrence by its nonvolatile glycoside, introducing a promising new option for engineering aphid control into plants.     

冷饭团不同部位挥发性成分及抗氧化活性分析

为较全面地认识冷饭团(Kadsura coccinea)植株挥发性成分及其抗氧化活性,该研究以其根、茎、叶为材料,采用水蒸气蒸馏提取法(方法 a)和顶空-固相微萃取法(SPME)(方法 b)结合气相色谱-质谱联用技术(GC-MS)与计算机检索技术,对冷饭团植株各部位挥发性成分进行了提取分析,并采用DPPH法对其抗氧化活性进行测试。结果表明:(1)两种提取方法检测出的挥发性成分种类及含量存在一定差异,用方法a和方法 b分别在根、茎、叶中共鉴定出挥发性化合物98和117种;其中根中分别有59与68种(占总挥发性物质的83.5%,93.8%)、茎中54和56种(占总挥发性物质的88.9%,94.9%)、叶中36和42种(占总挥发性物质的89.6%,97.7%)。(2)根、茎、叶中两种方法检出共同化合物种类及含量基本相同,主要有石竹烯、蒎烯、榄香烯、毕澄茄油烯、古巴烯、毕澄茄烯、d-苦橙花醇等,这些成分也是各部分挥发物的主要成分(含量超过70%)。(3)根、茎、叶中挥发性物质质量浓度达到20 mg·m L~(-1)时,清除DPPH自由基效率均超过97%,表现出很好的抗氧化活性。     

Mathematical modeling of ethanol production in solid-state fermentation based on solid medium’ dry weight variation

In this work, mathematical modeling of ethanol production in solid-state fermentation (SSF) has been done based on the variation in the dry weight of solid medium. This method was previously used for mathematical modeling of enzyme production; however, the model should be modified to predict the production of a volatile compound like ethanol. The experimental results of bioethanol production from the mixture of carob pods and wheat bran by Zymomonas mobilis in SSF were used for the model validation. Exponential and logistic kinetic models were used for modeling the growth of microorganism. In both cases, the model predictions matched well with the experimental results during the exponential growth phase, indicating the good ability of solid medium weight variation method for modeling a volatile product formation in solid-state fermentation. In addition, using logistic model, better predictions were obtained.     

Associations of rumen parameters with feed efficiency and sampling routine in beef cattle

Characterizing ruminal parameters in the context of sampling routine and feed efficiency is fundamental to understand the efficiency of feed utilization in the bovine. Therefore, we evaluated microbial and volatile fatty acid (VFA) profiles, rumen papillae epithelial and stratum corneum thickness and rumen pH (RpH) and temperature (RT) in feedlot cattle. In all, 48 cattle (32 steers plus 16 bulls), fed a high moisture corn and haylage-based ration, underwent a productive performance test to determine residual feed intake (RFI) using feed intake, growth, BW and composition traits. Rumen fluid was collected, then RpH and RT logger were inserted 5.5±1 days before slaughter. At slaughter, the logger was recovered and rumen fluid and rumen tissue were sampled. The relative daily time spent in specific RpH and RT ranges were determined. Polynomial regression analysis was used to characterize RpH and RT circadian patterns. Animals were divided into efficient and inefficient groups based on RFI to compare productive performance and ruminal parameters. Efficient animals consumed 1.8 kg/day less dry matter than inefficient cattle (P⩽0.05) while achieving the same productive performance (P⩾0.10). Ruminal bacteria population was higher (P⩽0.05) (7.6×10¹¹ v. 4.3×10¹¹ copy number of 16S rRNA gene/ml rumen fluid) and methanogen population was lower (P⩽0.05) (2.3×10⁹ v. 4.9×10⁹ copy number of 16S rRNA gene/ml rumen fluid) in efficient compared with inefficient cattle at slaughter with no differences (P⩾0.10) between samples collected on-farm. No differences (P⩾0.10) in rumen fluid VFA were also observed between feed efficiency groups either on-farm or at slaughter. However, increased (P⩽0.05) acetate, and decreased (P⩽0.05) propionate, butyrate, valerate and caproate concentrations were observed at slaughter compared with on-farm. Efficient had increased (P⩽0.05) rumen epithelium thickness (136 v. 126 µm) compared with inefficient cattle. Efficient animals also spent 318% and 93.2% more time (P⩽0.05) in acidotic (4.14% v. 1.30%) (pH⩽5.6) and optimal (5.6<pH<6.0) (8.53% v. 4.42%) RpH range compared with inefficient cattle. The circadian patterns revealed lower (P⩽0.05) RpH and no differences (P⩾0.10) in RT pre-, during, and post-prandial periods in efficient compared with inefficient cattle. In essence, superior feed efficiency in cattle seems linked to rumen features consistent with improved efficiency of feed utilization. Microbial abundance, rumen epithelial histomorphology, and RpH, may serve as indicators for feed efficiency in cattle. The divergences of assessments made on-farm and at slaughter should be considered in the development of proxies for feed efficiency.     

Moult in the Loggerhead Shrike Lanius ludovicianus is influenced by sex,latitude and migration

We investigated moult strategies in Loggerhead Shrikes by examining first prebasic or preformative moult patterns and by assessing the general location where individual feathers were grown using stable hydrogen isotope (δ²H) analysis. We tested the relative importance of factors known to impact moult timing and pattern, including age, sex, body size, food availability and migration. Migratory Shrikes showed evidence of suspended moult, in which feathers are moulted on both the breeding and the non‐breeding grounds with a suspension of moult during migration. Extent of moult was best explained by sex, longitude, migratory behaviour and breeding‐ground latitude. Male Hatch Year (HY) Shrikes replaced more feathers on the breeding grounds prior to migration than did HY females and moulted more extensively on the breeding grounds than did females. Non‐migratory HY Shrikes underwent a more extensive preformative moult than migratory HY Shrikes. Individuals in more southerly migratory populations moulted more extensively on the breeding grounds than did those breeding further north. Our data also indicate that individuals in the northeastern populations moulted more extensively on the breeding grounds than did those in the north and southwest. Our study underlines the complex structure and variation in moult possible within species, revealing surprising levels of differentiation between sexes and age cohorts, linked to environmental factors on the breeding grounds. Our study highlights the utility of an intrinsic marker, specifically δ²H analysis, to test hypotheses regarding the evolutionary and ecological forces driving moult. Although the methodology has not commonly been applied to this area of research, our results indicate that it can provide unprecedented insight into inter‐ and intra‐specific adaptive response to constraints, whereby individuals maximize fitness.