水杨酸对大叶黄杨茎抗寒性和电阻抗图谱参数的影响

在抗寒锻炼前,对当年生大叶黄杨(Euonymus japonicus)扦插苗喷施不同浓度水杨酸,用电阻抗图谱(EIS)法和电导(EL)法估测茎的抗寒性,以探明抗寒锻炼期间水杨酸对大叶黄杨抗寒性和电阻抗图谱参数的影响,找到适合不经冷冻处理估测大叶黄杨茎抗寒性和经冷冻处理后测定其抗寒性的EIS参数。结果表明,水杨酸处理能够提高大叶黄杨茎的抗寒性,最适浓度为5.0mmol.L-1;不经冷冻处理茎的EIS参数电阻率r和r1、胞外电阻率re、胞内电阻率ri、弛豫时间τ、弛豫时间分布系数ψ与EL法测定的抗寒性有较高的相关性(r=0.70~0.87),说明不经冷冻处理样本用以上参数估测大叶黄杨茎抗寒性是可行的,r1为最佳参数;冷冻处理后茎的re、τ、ri求得的抗寒性与EL法测定的抗寒性有较高的相关性(r=0.85~0.94),说明冷冻处理后re、τ、ri可以作为测定大叶黄杨茎抗寒性的参数,re为最佳参数。     

电导法和电阻抗图谱法测定脱锻炼期间欧美杨×大青杨F_1子代抗寒性

利用电导（EL）法和电阻抗图谱（EIS）法对脱锻炼期间欧美杨‘107杨’（Populus×canadensis Moench cv.‘Neva’）×大青杨（P.ussuriensis Kom.）F1子代进行抗寒性测定,试图通过比较两种方法测定抗寒性结果的相关性,以确定EIS法快速测定‘107杨’×大青杨F1子代抗寒性的最佳参数。以8个杂种子代和母本‘107杨’3年生为试材,进行了电阻抗图谱法和电导法分析,结果表明：脱锻炼期间,各子代抗寒性均逐渐降低,依次为NK36〉NK41〉NK61〉NK57〉NK42〉NK60〉NK58〉NK56,均高于‘107杨’,EIS参数弛豫时间[EIS（τ）法]和EL法的抗寒性测定结果间存在明显的线性相关（R2=0.965）,但EIS法测定的抗寒性低于EL法,且未经冷冻处理样本的胞外电阻率（re）和弛豫时间（τ）与经冷冻处理EL测定的抗寒性有较高的相关性,R2分别为0.817和0.847。     

电导法和电阻抗图谱法测定脱锻炼期间欧美杨×大青杨F1子代抗寒性

利用电导(EL)法和电阻抗图谱(EIS)法对脱锻炼期间欧美杨‘107杨’(Populus×canadensis Moench cv.‘Neva’)×大青杨(P.ussuriensis Kom.)F1子代进行抗寒性测定,试图通过比较两种方法测定抗寒性结果的相关性,以确定EIS法快速测定‘107杨’×大青杨F1子代抗寒性的最佳参数。以8个杂种子代和母本‘107杨’3年生为试材,进行了电阻抗图谱法和电导法分析,结果表明:脱锻炼期间,各子代抗寒性均逐渐降低,依次为NK36>NK41>NK61>NK57>NK42>NK60>NK58>NK56,均高于‘107杨’,EIS参数弛豫时间[EIS(τ)法]和EL法的抗寒性测定结果间存在明显的线性相关(R2=0.965),但EIS法测定的抗寒性低于EL法,且未经冷冻处理样本的胞外电阻率(re)和弛豫时间(τ)与经冷冻处理EL测定的抗寒性有较高的相关性,R2分别为0.817和0.847。     

CaCl2对金叶女贞茎抗寒性和电阻抗图谱参数的影响

为探明CaC l2处理对金叶女贞（Ligustrum vicaryi）茎抗寒性和电阻抗图谱参数的影响,找出抗寒性和电阻抗图谱参数的关系,2006年9月15日开始对金叶女贞当年生扦插苗进行CaC l2处理,对照为清水;分别用电阻抗图谱法和电导法估测其抗寒性,并进行比较分析。结果表明：CaC l2处理能在抗寒锻炼初期使金叶女贞茎的抗寒性提高3.5℃,金叶女贞茎的抗寒性与未冷冻处理茎的弛豫时间τ、冷冻处理后茎的胞外电阻率re、含水量之间均存在较高的相关性。     

测定植物抗寒性的电阻抗图谱法

电阻抗图谱(electrical impedance spectroscopy,EIS)分析作为测定植物抗寒性的一种方法,在农业、林业和园艺领域的应用正在不断扩大。该文从EIS的原理入手,讨论了影响电阻抗特性的生理和物理因子;介绍了测定EIS适用的模型;阐述了用EIS测定抗寒性的方法。在EIS分析中,胞外电阻率(re)是确定抗寒性最适用的一个参数,弛豫时间(τ1)是精确度最高的参数。     

春季白皮松实生苗的脱锻炼与再锻炼

春季测定二年生白皮松实生苗脱锻炼期间针叶和茎的抗寒性和估测脱锻炼结束后经低温(4℃)处理1周后幼苗的再锻炼能力,以及测定低温处理前后不同器官干物质含量的结果表明:脱锻炼后,一年生针叶的最小抗寒性为-10.4℃,一年生茎为-6.7℃.在低温诱导下,白皮松苗具有再锻炼能力,一年生针叶和茎的抗寒性分别增强约7和9℃;一年生针叶和茎的抗寒性均高于当年生的.再锻炼期间,一年生针叶和茎的抗寒性与干物质含量呈正相关.     

电阻抗图谱法在刺槐种质资源抗寒性测定中的应用

电阻抗图谱(EIS)法作为测定植物抗寒性的一种方法,在农业、林业和园艺领域的应用正在不断扩大,本文以12个刺槐种质资源4年生试验林当年生枝条为材料,应用EIS法对各刺槐种质资源抗寒性进行了测定,对比分析了6个参数(τ、ψ、r、r1、re、ri)的数学意义,并与电导率法进行了对比.结果表明:在刺槐种质资源抗寒性研究中,胞外电阻率(re)是最适用的一个参数,能够较好反映出不同种质资源抗寒能力;采用EIS法测定不同种质资源抗寒性结果与传统的电导率法测定结果基本一致,但省时、不需温育,具有更大的优越性.     

CaCl2对金叶女贞茎抗寒性和电阻抗图谱参数的影响

为探明CaCl₂处理对金叶女贞(Ligustrum vicaryi)茎抗寒性和电阻抗图谱参数的影响,找出抗寒性和电阻抗图谱参数的关系,2006年9月15日开始对金叶女贞当年生扦插苗进行CaCl₂处理,对照为清水;分别用电阻抗图谱法和电导法估测其抗寒性,并进行比较分析。结果表明：CaCl₂处理能在抗寒锻炼初期使金叶女贞茎的抗寒性提高3.5℃,金叶女贞茎的抗寒性与未冷冻处理茎的弛豫时间τ、冷冻处理后茎的胞外电阻率r_e、含水量之间均存在较高的相关性。     

基于电阻抗图谱估测金丝楸茎和叶可溶性糖含量的模型

以金丝楸(Catalpa bungei C.A.Mey)为试材,在抗寒锻炼期间分析其茎和叶的电阻抗图谱(electrical impedance spectroscopy,EIS)、可溶性糖含量及细胞膜透性。将茎和叶的EIS参数分别与相应的可溶性糖含量进行线性和非线性回归分析,选取最佳EIS参数构建估测模型,并对模型的精度进行检验,同时,用电阻抗图谱法和电解质渗出率法对金丝楸的抗寒性进行测定。结果表明:1)随着抗寒锻炼的进程,金丝楸茎和叶的可溶性糖含量均呈上升趋势。2)抗寒锻炼期间,金丝楸茎的EIS单弧逐渐变大,弧顶电抗值呈现下降趋势。叶的EIS单弧先变大后变小,弧顶电抗值呈现先减小后增大的趋势。3)金丝楸茎高频电阻率r为估测茎可溶性糖含量的最佳EIS参数,叶弛豫时间分布系数ψ为估测叶可溶性糖含量的最佳EIS参数,分别构建最佳估测模型r=-0.0177x2+0.889x+8.5912和ψ=0.0068x3-0.2023x2+1.2192x+18.4860,对模型进行检验,预测精度分别达到91.62%和81.06%。4)采用电解质渗出率法与高频电阻率r和弛豫时间分布系数ψ测定的茎和叶的抗寒性较为接近,平均绝对误差值分别为3.01和2.83。     

涝胁迫下白桦叶和茎含水量的电阻抗图谱估测

通过人工模拟涝胁迫, 在不同时期测定涝胁迫下白桦(Betula platyphylla)叶和茎的电阻抗图谱(electrical impedance spectroscopy, EIS)和相应叶和茎的含水量及细胞膜透性。对叶和茎EIS参数与其含水量以及细胞膜透性数据分别进行相关分析, 采用单变量线性和非线性回归技术, 选取部分样本数据建立涝胁迫下白桦叶和茎的含水量估测模型, 并利用其余的样本对模型进行检验。用EIS法和电导法估测其耐涝时间。取得如下结果。(1) 随着涝胁迫时间的延长, 涝处理中白桦叶和茎的含水量均呈下降趋势。(2) 涝胁迫下叶的EIS中弧顶电抗值呈降低的趋势, 而茎的EIS中弧顶电抗值呈先升高, 后降低的趋势。(3) 涝胁迫下白桦叶和茎的含水量及细胞膜透性与部分EIS参数显著相关, 并通过选取相关性最佳的EIS参数, 构建了涝胁迫下叶和茎含水量的估算模型。其中, 高频电阻率(r)对叶和茎含水量的估算效果最好, 最佳估算模型分别为y_叶=1.066 8e^−0.11x和y_茎=0.000 7x²+0.003 7x+0.525 4。对以上模型进行测试和检验, 均取得了较为理想的预测精度, 分别为84.30%和94.34%。表明可以用EIS信息估测涝胁迫下白桦叶和茎的含水量, 其估算模型有较高的可靠性与普适性。(4) 白桦实生苗可忍受30天以上涝害胁迫。该研究结果对利用EIS技术监测逆境下林木生理状况及生长趋势具有实用价值。     

Fluorescence anisotropy studies of molecularly imprinted polymers.

A molecularly imprinted polymer (MIP) is a biomimetic material that can be used as a biochemical sensing element. We studied the steady-state and time-resolved fluorescence and fluorescence anisotropy of anthracene-imprinted polyurethane. We compared MIPs with imprinted analytes present, MIPs with the imprinted analytes extracted, MIPs with rebound analytes, non-imprinted control polymers (non-MIPs) and non-MIPs bound with analytes to understand MIP's binding behaviour. MIPs and non-MIPs had similar steady-state fluorescence anisotropy in the range 0.11-0.24. Anthracene rebound in MIPs and non-MIPs had a fluorescence lifetime of tau = 0.64 ns and a rotational correlation time of phi(F) = 1.2-1.5 ns, both of which were shorter than that of MIPs with imprinted analytes present (tau = 2.03 ns and phi(F) = 2.7 ns). The steady-state anisotropy of polymer solutions increased exponentially with polymerization time and might be used to characterize the polymerization extent in situ.     

Kinetics of the growth of Toxoplasma gondii (RH strain) in mice.

A method is described for obtaining maximum yield of Toxoplasma tachyzoites from the peritoneal cavity of infected mice. Mice injected with 10² parasites contain more Toxoplasma in this site at the time of death than mice injected with larger numbers. The host does not mount a detectable humoral response to the parasite.     

A Photochemical Mechanism for Homochirogenesis. Part 2

A theoretical investigation of the photochemistry of racemic compounds with circularly polarized light was undertaken. The exact solutions of the differential equations by numerical integration to the approximate solutions used in an earlier article were compared. The exact solutions showed that sequential reactions yield enhanced optical activities in the products. For irreversible reactions, all enantiomeric excesses are lost if the reactions are carried to completion, but appreciable resolution occurs in many cases for partial conversion. For reversible reactions, significant enantiomeric excesses are found at the photostationary state. Chirality 25:16‐21, 2013. © 2012 Wiley Periodicals, Inc.     

精氨酸氨化方法的干扰因素分析

精氨酸氨化方法的干扰因素分析林启美（中国农业大学土壤和水科学系,北京１０００９４）ＴｈｅＩｎｔｅｒｆｅｒｉｎｇＦａｃｔｏｒｓｏｆＡｒｇｉｎｉｎｅＡｍｍｏｎｉｆｉｃａｔｉｏｎＭｅｔｈｏｄ．ＬｉｎＱｉｍｅｉ（ＤｅｐａｒｔｍｅｎｔｏｆＳｏｉｌａｎｄＷａｔｅ...     

Aggregation states of mitochondrial malate dehydrogenase.

The oligomeric state of fluorescein-labeled mitochondrial malate dehydrogenase (L-malate NAD+ oxidoreductase; mMDH; EC 1.1.1.37), as a function of protein concentration, has been examined using steady-state and dynamic polarization methodologies. A "global" rotational relaxation time of 103 +/- 7 ns was found for micromolar concentrations of mMDH-fluorescein, which is consistent with the reported size and shape of mMDH. Dilution of the mMDH-fluorescein conjugates, prepared using a phosphate buffer protocol, to nanomolar concentrations had no significant effect on the rotational relaxation time of the adduct, indicating that the dimer-monomer dissociation constant for mMDH is below 10(-9) M. In contrast to reports in the literature suggesting a pH-dependent dissociation of mMDH, the oligomeric state of this mMDH-fluorescein preparation remained unchanged between pH 5.0 and 8.0. Application of hydrostatic pressure up to 2.5 kilobars was ineffective in dissociating the mMDH dimer. However, the mMDH dimer was completely dissociated in 1.5 M guanidinium hydrochloride. Dilution of a mMDH-fluorescein conjugate, prepared using a Tris buffer protocol, did show dissociation, which can be attributed to aggregates present in these preparations. These results are considered in light of the disparities in the literature concerning the properties of the mMDH dimer-monomer equilibrium.     

Coexistence of ecologically similar colonising species. II. Population differentiation in Drosophila aldrichi and D. Buzzatii for competitive effects and responses at different temperatures and allozyme variation in D. aldrichi

Drosophila aldrichi and D. buzzatii are cactophilic species that colonised Australia about 55–60 years ago. They are sympatric only in Australia. Thus they may be in the process of adapting to new environments and to each other, and diversifying among local, possibly isolated, populations. Larval competitive effects for three populations of each species (Roma, Planet Downs, and Binjour) were measured on semi-natural cactus rots at three temperatures, with preadult viability, developmental time and adult body weight scored for each sex and species. Populations of both species varied in their responses to the other species as competitor, and one D. buzzatii population (Roma) reduced larval performance of D. aldrichi significantly more than did other D. buzzatii populations. Geographic divergence for the three traits was similar in both species, with a relative performance index derived from these traits highest for Roma, second for Binjour, and least for the Planet Downs population of each species. The Roma D. aldrichi population was the most different from the other populations for the performance index and in terms of genetic distances derived from allozyme frequencies. Additionally, comparisons of climatic variables among the population localities showed that the Roma environment was most different from the others. Differential natural selection in different areas of the cactus distribution may be a major cause of population divergence in both species. Drosophila aldrichi is superior for some fitness components at the highest temperature. Thus temperature variation throughout the cactus distribution may contribute to the different ranges of these two species, with competitive exclusion of D. aldrichi in the southern, cooler region of the cactus distribution, but coexistence in the northern, warmer region.     

Improvement of carbon dioxide biofixation in a photobioreactor using Anabaena sp. PCC 7120

The biological photosynthetic process is useful and environmentally benign compared with other carbon dioxide (CO₂) mitigation processes. In the present study, Anabaena sp. PCC 7120 was utilized for carbon dioxide mitigation. A customized airlift photobioreactor was found to provide higher light utilization efficiency and a higher rate of CO₂ biofixation compared with that of a bubble column. The maximum biomass concentrations were 0.71 and 1.13 g L^?1 in the bubble column and airlift photobioreactor, respectively, using BG11₀ medium under aerated conditions. A lower mixing time in the airlift photobioreactor compared with that of the bubble column resulted in improved mass transfer. The CO₂ biofixation rate of Anabaena sp. PCC 7120 was determined using different phosphate concentrations at a light intensity of 120 μE m^?2 s^?1 and 5% (v/v) CO₂-enriched air in the airlift photobioreactor. However, it was observed that the specific growth rate was independent at higher light intensity. In addition, it was observed that increased light intensity, phosphate and CO₂ concentrations could enhance the CO₂ biofixation efficiency to a greater extent.     

Abdominal Waggings and Variation of Their Rate of Occurrence in the Social Wasp, Polistes dominulus Christ. I. Quantitative Analysis

The quantitative study of abdominal waggings in Polistes dominulus Christ, covering a total of 16,000 sequences of movements observed in 13 colonies (mono- and polygyne), showed or confirmed the following points. The same form of abdominal wagging, very frequent in this species, is carried out by foundresses in two contexts: when they are caring for their brood and during aggressive encounters with other adults. While the dominant female shows this behavior most often, it predominantly concerns aggressive waggings (0.51 sequence per social interaction for alpha females, 0.12 and 0.04 for beta and gamma); the movements related to feeding larvae are distributed much better among the foundresses of Polygyne nests (0.38 sequence per cell check for alpha, 0.24 and 0.21 for beta and gamma). The number of waggings carried out by the workers is negligible in normally constituted colonies (0.006 and 0.01, respectively, for the two contexts). The rate of occurrence of abdominal waggings changes with time. This change is opposite and symmetrical for the two types of waggings, although we were not able to establish any correlation between the number of the movements linked to feeding the larvae and the abundance or the composition of the brood. Abdominal wagging therefore appears as a means of communication between the different members in Polistes society, used in varying degrees by all foundresses; the change of its rate of occurrence over time suggests a possible influence on larvae, hence on the future status of newborn wasps (workers or future foundresses).     

Patterns of temporal variation in Lake Titicaca. A high altitude tropical lake. I. Background,physical and chemical processes,and primary production

A statistical analysis is presented of patterns of variation in some physical, chemical, and biological variables for a 6 year series of data from the tropical, high altitude Lake Titicaca (Peru-Bolivia). ANOVA techniques and autocorrelation analyses were used to partition the variance in Titicaca, and in some comparison tropical and temperate series, into components with repeatable annual cycles and components attributable to other kinds of patterns.In Titicaca, insolation and stratification are highly seasonal in pattern of variation, although the amount of variance relative to means is small compared to temperate lakes. However, the seasonal pattern of physical variation is only weakly imposed on chemical and biological processes, to judge from analyses of silicate, oxygen, and primary production series. Comparable temperate series of primary production and chlorophyll a are much more seasonal.