蒸散发广义互补原理中关键参数αe的时空变化特征及计算方法分析

蒸散发广义互补原理是实测数据稀少条件下估算蒸散发的重要方法, 其中准确估算参数α_e是应用该方法的关键。该研究利用中国不同气候和生态类型的8个通量站数据, 首先基于实测数据校准得到α_e年值及月值, 探究α_e的时空变异性并对比使用不同时间尺度的α_e对广义互补原理模型计算精度的影响。考虑到实际情况下蒸散发实测数据缺乏而无法校准得到α_e, 进一步探究两个基于干旱系数(AI)的α_e年值统计模型(下称Liu法和Brutsaert法)在站点尺度的适用性, 明确α_e是否可以利用AI确定, 最后探讨各计算方法的误差来源。主要结论如下: 1)季节变化影响α_e, 不同通量站α_e月值变化规律有所差异; 在空间变化上, 湿润站点α_e年值总体大于干旱站点。Liu法和Brutsaert法计算的α_e接近年校准值。2)在应用广义互补原理模型时, 使用校准α_e年值能取得较好的模拟精度, 使用各月份α_e时精度进一步提升。两种基于AI的免校准方法取得较好的模拟效果, 当缺少实测数据而无法校准α_e时, 基于AI计算α_e具有较大的潜力。3)使用校准α_e年值时广义互补原理模型能模拟出蒸散发的年内变化趋势, 但在部分月份估算值出现偏差。Liu法和Brutsaert法计算的蒸散发在干旱站点的夏季月份呈现低估现象, 原因可能在于高估了降雨集中的夏季月份的AI。结果也进一步验证了广义互补原理在估算广泛不同的自然环境下的蒸散发的潜力。     

How are neuronal thermosensitivity and lack of thermoreception related in the duck's hypothalamus? A tentative answer

1. 1.|In 15 conscious Pekin ducks, 40 “warm sensitive” hypothalamic neurons were identified according to their discharge rates at 40°C T_hy (F₄₀), local temperature coefficients (Δ/ΔT) and Q₁₀.

2. 2.|Q₁₀ and either F₄₀ or ΔF/ΔT were little or not related.

3. 3.|A positive correlation between F₄₀ and ΔF/ΔT was observed which was particularly close (r = 0.94 and 0.96) when the neurons were classified according to their Q₁₀ of <2 and >2.

4. 4.|The results suggest that neurons with positive temperature coefficients in the duck's hypothalamus mostly exhibit linear to exponential temperature-discharge relationships.

5. 5.|This is an contrast to observations on mammalian hypothalamic thermosensitive neurons and may relate to the absence of the thermosensory function in the duck's rostral brainstem.

Comparison of different European strains of Trichogramma aurosum (Hymenoptera: Trichogrammatidae) using fertility life tables

Life table parameters were assessed for seven strains of Trichogramma aurosum Sugonjaev and Sorokina (Hymenoptera: Trichogrammatidae) collected in different European countries, in order to compare their performance when reared on eggs of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) as a potential factitious host for mass-rearing. The average number of progeny per female, cumulative fertility and emergence rate did not differ significantly, whereas female longevity and sex ratio significantly differed between the seven parasitoid strains. The Danish strain survived the longest (6.05 days) and the Dutch strain survived the shortest (2.75 days). Progeny was always female-biased with varying proportions (57.7-96.7%). Survival rates started to decrease after 3 days for some of the strains studied. The mean cohort generation duration (T_c) was 11.40, 10.15, 10.62, 10.63, 9.28, 9.70 and 11.30 days for the Austrian, Luxemburgian, Belgian, French, Dutch, Danish and German strains, respectively. Population doubling time (D_t) was 4.50, 7.96, 3.56, 5.30, 5.23, 7.36 and 3.30 days, respectively. Daily intrinsic rate of increase (r_m) and finite rate of increase (exp. r_m) ranged between 0.087 and 0.210 and 1.091-1.233, respectively. The German strain might be a potential candidate for mass rearing and releases against the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), due to its high net reproduction rate (R₀=10.65 female), a high intrinsic rate of natural increase (r_m=0.210), a high finite rate of increase (exp. r_m=1.23), and a short population doubling time (D_t=3.3 days). The relevance of intra- and interstrain variability as well as the usefulness of fertility life tables for pre-introductory research is discussed.     

岷江柏野生居群和迁地保护居群的遗传多样性比较

通过分析岷江柏的迁地保护居群和野生居群的遗传多样性、遗传结构及居群间基因流,判断迁地保 护岷江柏居群的遗传多样性水平,为其迁地保护提供理论基础。本研究利用GBS（Genotyping-by-Sequencing） 测序技术获得的SNP位点对四川大渡河双江口岷江柏迁地保护移栽苗、苗圃播种苗及3个野生居群进行主成分分析（PCA分析）、聚类分析、分子进化树、遗传多样性和遗传结构分析。经过GBS测序共获得高质量Clean Data 118 321 514 728 bp,并开发了1947 047个tags,从中鉴定到了1 259 610个SNP位点。系统发育进化树显示大部分移栽岷江柏居群和野生岷江柏聚在一起,居群结构分析结果显示交叉验证错误率的谷值确定最优分群数为1。4个岷江柏居群的观测杂合度（H_o）、期望杂合度（H_e）、Shannon信息指数I（S_hi）、近交系数（F_is）、多态信息含量（P_ic）的值分别为0.181 5~0.272 0、0.223 2~0.300 3、0.331 0~0.464 9、0.178 0~0.246 5和0.272 2~0.309 2,说明岷江柏居群的遗传多样性水平较高。移栽岷江柏居群的H_e=0.300 3,S_hi=0.464 9,岷江柏居群迁地保护居群遗传多样性总体水平略高于野生居群。野生岷江柏居群中白湾隧道（BW）_vs_松岗镇（SA）的遗传分化指数（F_st）较大,基因流（N_m）较小（F_st=0.091,N_m=2.496）,而迁地保护的岷江柏居群与野生岷江柏居群没有明显的遗传分化,居群间的基因交流频繁（F_st<0.05,基因流N_m>4）,说明没有明显的分群现象,岷江柏居群迁地保护居群遗传多样性较高。因此,移栽濒危植物是迁地保护过程中较好的方法,本文为以后野生岷江柏迁地保护提供参考,为其他树木种质资源的保存提供理论依据。     

利用直接法和间接法测定针阔混交林叶面积指数的季节动态

利用光学仪器法能够快速、高效地测定森林生态系统的叶面积指数(leaf area index, LAI)。然而, 评估该方法测定针阔混交林LAI季节动态准确性的研究较少。该研究基于凋落物法测定了小兴安岭地区阔叶红松(Pinus koraiensis)林LAI的季节动态, 其结果可代表真实的LAI。参考真实的LAI, 对半球摄影法(digital hemispherical photography, DHP)和LAI-2000植物冠层分析仪测定的有效叶面积指数(effective LAI, L_e)进行了评估。首先对DHP测定LAI过程中采用的不合理曝光模式(自动曝光)进行了系统校正。同时, 测定了光学仪器法估测LAI的主要影响因素(包括木质比例(woody-to-total area ratio, α)、集聚指数(clumping index, Ω_E)和针簇比(needle-to-shoot area ratio, γ_E))的季节变化。结果表明: 3种不同方法测定的LAI均表现为单峰型的季节变化, 8月初达到峰值。从5月至11月, DHP测定的L_e比真实的LAI低估50%-59%, 平均低估55%; 而LAI-2000植物冠层分析仪测定的L_e比真实的LAI低估19%-35%, 平均低估27%。DHP测定的L_e 经过自动曝光, α、Ω_E和γ_E校正后, 精度明显提高, 但仍比真实的LAI低估6%-15%, 平均低估9%; 相对而言, LAI-2000植物冠层分析仪测定的L_e经过α、Ω_E和γ_E校正后, 精度明显提高, 各时期与真实的LAI的差异均小于9%。研究结果表明, 考虑木质部和集聚效应对光学仪器法的影响后, DHP和LAI-2000植物冠层分析仪均能相对准确地测定针阔混交林LAI的季节动态, 其中, DHP的测定精度高于85%, 而LAI-2000植物冠层分析仪的测定精度高于91%。     

Measuring seasonal dynamics of leaf area index in a mixed conifer-broadleaved forest with direct and indirect methods

利用光学仪器法能够快速、高效地测定森林生态系统的叶面积指数(leaf area index, LAI)。然而, 评估该方法测定针阔混交林LAI季节动态准确性的研究较少。该研究基于凋落物法测定了小兴安岭地区阔叶红松(Pinus koraiensis)林LAI的季节动态, 其结果可代表真实的LAI。参考真实的LAI, 对半球摄影法(digital hemispherical photography, DHP)和LAI-2000植物冠层分析仪测定的有效叶面积指数(effective LAI, L_e)进行了评估。首先对DHP测定LAI过程中采用的不合理曝光模式(自动曝光)进行了系统校正。同时, 测定了光学仪器法估测LAI的主要影响因素(包括木质比例(woody-to-total area ratio, α)、集聚指数(clumping index, Ω_E)和针簇比(needle-to-shoot area ratio, γ_E))的季节变化。结果表明: 3种不同方法测定的LAI均表现为单峰型的季节变化, 8月初达到峰值。从5月至11月, DHP测定的L_e比真实的LAI低估50%-59%, 平均低估55%; 而LAI-2000植物冠层分析仪测定的L_e比真实的LAI低估19%-35%, 平均低估27%。DHP测定的L_e 经过自动曝光, α、Ω_E和γ_E校正后, 精度明显提高, 但仍比真实的LAI低估6%-15%, 平均低估9%; 相对而言, LAI-2000植物冠层分析仪测定的L_e经过α、Ω_E和γ_E校正后, 精度明显提高, 各时期与真实的LAI的差异均小于9%。研究结果表明, 考虑木质部和集聚效应对光学仪器法的影响后, DHP和LAI-2000植物冠层分析仪均能相对准确地测定针阔混交林LAI的季节动态, 其中, DHP的测定精度高于85%, 而LAI-2000植物冠层分析仪的测定精度高于91%。     

不同光脉冲方案对光下最大荧光参数及其计算参数的影响

光下最大荧光(F_m′)是植物生理生态研究中的重要参数,一般采用饱和脉冲(RF)方案来估计.然而,光系统Ⅱ(PSⅡ)受体库的反馈调节会影响RF方案对F_m′估计的准确性.为消除PSⅡ受体库反馈调节的影响,根据光脉冲强度(Q′)与叶绿素荧光(F′)的线性关系提出多相脉冲(MPF)方案,估算Q′无穷大时的F′(即F_m′).本研究采用MPF和RF方案分别对苦槠、青冈和乌桕3个树种叶片的叶绿素荧光和气体交换数据进行同步测量,并对两种方案估计的F_m′及其计算参数PSⅡ光化学效率(Φ_PSII)、PSⅡ的电子传递速率(J)、最大电子传递速率(J_max)、叶肉导度(g_m)和叶绿体内CO₂浓度(C_c)等光合参数进行比较,分析两种方案对3个树种叶片6个光合参数的影响.结果表明: 当光合有效辐射(PAR)<200 μmol·m^-2·s^-1时,两种方案对苦槠、青冈和乌桕叶片F_m′、Φ_PSII和J的估计无显著影响;当PAR>200 μmol·m^-2·s^-1时,采用MPF方案获得的苦槠、青冈和乌桕的F_m′分别比RF方案获得的F_m′高3.5%～5.2%、11.7%～18.0%和3.2%～7.1%;当PAR>200 μmol·m^-2·s^-1时,采用MPF方案获得的Φ_PSII、J和J_max分别不同程度地大于RF方案获得的参数,g_m和C_c分别不同程度地小于RF方案获得的参数.说明当PAR较低(<200μmol·m^-2·s^-1)时,MPF与RF方案对植物叶片F_m′、Φ_PSII、J的估计没有显著影响;当PAR较高(≥200μmol·m^-2·s^-1)时,MPF与RF方案对植物叶片F_m′、Φ_PSII、J、J_max、g_m和C_c的估计有显著影响,且RF方案对植物叶片的F_m′、Φ_PSII、J和J_max比MPF方案分别有不同程度的低估,对g_m和C_c则有不同程度的高估.     

Allozyme differentiation in four species of the Crocus cartwrightianus group and in cultivated saffron (Crocus sativus)

The genetic variability and divergence of four species of the genus Crocus L., related to Crocus cartwrightianus group, namely Crocus thomasii Ten., Crocus hadriaticus Herbert, Crocus oreocreticus B.L. Burtt, C. cartwrightianus Herbert, has been studied by means of starch gel isozyme electrophoresis. For each population the following enzymatic loci were analyzed: PGI-1, PGI-2, G6PDH-1, G6PDH-2, IDH-1, IDH-2, 6PGDH-1, 6PGDH-2, SKDH-1, SKDH-2, AK-1 and AK-2. The genetic variability was estimated through the parameters A (mean number of alleles per locus), P (percent of polymorphic loci), H_o (mean observed heterozygosity), and H_e (mean expected heterozygosity). The genetic differentiation has been assayed by Wrigth's F-statistics, and the genetic divergence by Nei's index. Our data confirmed that the taxa are distinct species, in spite of their similar morphology and karyology. C. thomasii is more genetically similar to C. cartwrightianus and C. oreocreticus than to C. hadriaticus. We hypothesized an autopolyploid origin of saffron, probably from C. cartwrightianus, considering the genotypic classes of Crocus sativus and the other related species of the C. cartwrightianus group studied here.     

Green plastids, maximal PSII photochemical efficiency and starch content of inner stem tissues of three Mediterranean woody species during the year

Wood and pith of 1–2-year-old stems of three woody species with different life strategies common in the Mediterranean basin were studied during the year regarding (i) the occurrence of green plastids, (ii) their maximal photosystem II photochemical efficiency (F_v/F_m) and (iii) their starch content. Green plastids were identified from the red chlorophyll auto-fluorescence under epi-fluorescence microscope, F_v/F_m was estimated using imaging-PAM fluorometry and starch content was recorded under bright field microscope after iodine staining. The evergreen sclerophyll Nerium oleander, the summer deciduous Euphorbia acanthothamnos and the winter deciduous species Platanus orientalis were selected for the study.

Epi-fluorescence microscopy revealed that (i) all species possess abundant green plastids in their wood ray and pith cells throughout the year. In the winter deciduous species chlorophyll fluorescence was found to be strong during the leafless period. By contrast, in the evergreen and the summer deciduous species chlorophyll fluorescence was found uniformly bright during the year; (ii) F_v/F_m value variation during the year seems to be species-specific: in the wood of N. oleander it remains unchanged whereas in the pith it is low during spring–summer; in both tissues of E. acanthothamnos F_v/F_m value reaches maximal value during spring and in P. orientalis during autumn; (iii) in N. oleander and E. acanthothamnos starch is accumulated during spring, whereas in P. orientalis starch content is high during winter.

The scanning electron microscopy (SEM) investigation revealed that the stem epidermis of all three species lacks stomata and formation of lenticels is delayed. Provided that gas exchange is therefore minimized and that PSII photochemical efficiency of inner stem tissues is relatively high, it is further supported that green plastids of wood ray and pith cells may help toward the re-fixation of the internally respired CO₂.     

CO2储存通量估算方法对森林生态系统碳收支估测的影响

准确测定森林生态系统中CO₂储存通量(F_s)对于以涡动协方差(EC)法估算生态系统碳收支具有重要意义,而F_s不同算法引起的森林碳收支估测误差还未被全面评估。本研究利用2018年帽儿山落叶阔叶林的开路EC系统和8层CO₂/H₂O廓线系统(AP100, Campbell Scientific Inc., USA)数据,比较了2-min平均廓线(P_{2 min})、30-min平均廓线(P_{30 min})和30-min平均EC单点法(P_s)3种不同方法估算的F_s对净生态系统交换(NEE)、生态系统呼吸(R_e)和总初级生产力(GPP)估算结果的影响。结果表明: F_s估算方法对森林碳通量的影响总体上随时间尺度增大而不断增大,表明通量数据插补和拆分会进一步放大F_s估算方法的影响。在年尺度上,P_{2 min}法和P_s法的NEE分别比P_{30 min}法的低36.3%和29.4%;P_{2 min}法的R_e比P_{30 min}法和P_s法高8.7%;而P_{2 min}法的GPP比P_{30 min}法的高5.4%,P_s法则比P_{30 min}法的低2.1%。传统的P_{30 min}法忽略了CO₂浓度的瞬时变化,P_s法缺少林冠层内部CO₂浓度变化,因此两者低估了真实R_e。近似瞬时廓线的方法(2-min平均)具有更高的时间与空间分辨率,能够更加准确地估算非平坦地形和复杂冠层结构的森林碳收支,这对解决EC法在复杂条件下森林R_e和GPP低估、净碳汇高估具有重要启示。     

Extracting absolute titanium-alkyl and-hydride bond enthalpies from relative D(TiR(H)) in (silox)2(Bu3SiNH)TiR: electronegativity and ECT models

Relative D(Ti-R)_rel have been measured previously for (silox)₂(^tBu₃SiNH)TiR (1-R). Pauling and Matcha equations of D(MR) that contain elements of electronegativity, D(MM), D(HH) and D(RH) were used to estimate absolute D(TiR) in 1 with minimal success. The electronegativity approaches need a variety of substituents with a wide spread in χ_R, hence examination of 1-H and 1-R are heavily and incorrectly weighted by D(TiH)-D(TiR). Absolute D(TiR) generated in this manner approach those of related systems only when χX_Ti = 2.9, a value shown to be irrational. Drago's ECT parameters were used in the hope that the three parameter fit would compensate for inadequacies in electronegativity-based methods. The limited set of alkyl parameters available, and a lack of distinguishing parameters that can significantly differentiate one alkyl from another, render this potentially useful method imprecise.     

The radiosensitivity of spermatogonial stem cells in C3H/101 F1 hybrid mice

The radiosensitivity of spermatogonial stem cells of C3H/HeH × 101/H F₁ hybrid mice was determined by counting undifferentiated spermatogonia at 10 days after X-irradiation. During the spermatogenic cycle, differences in radiosensitivity were found, which were correlated with the proliferative activity of the spermatogonial stem cells. In stage VIII_irr, during quiescence, the spermatogonial stem cells were most radiosensitive with a D₀ of 1.4 Gy. In stages XI_irr−V_irr, when the cells were proliferatively active, the D₀ was about 2.6 Gy. Based on the D₀ values for sensitive and resistant spermatogonia and on the D₀ for the total population, a ratio of 45:55% of sensitive to resistant spermatogonial stem cells was estimated for cell killing.

When the present data were compared with data on translocation induction obtained in mice of the same genotype, a close fit was obtained when the translocation yield (Y; in % abnormal cells) after a radiation dose D was described by Y = e^τD, with τ = 1 for the sensitive and τ = 0.1 for the resistant spermatogonial stem cells, with a maximal e^τD of 100.     

东江外来齐氏罗非鱼个体繁殖力初步研究

于2011年1月至2011年12月,逐月在东江采集齐氏罗非鱼样本, 研究其个体繁殖力。结果表明, 齐氏罗非鱼属于多次产卵类型, 在东江的繁殖期约为5月初到10月底。个体绝对繁殖力(F)在4913~13129粒之间, 平均为7991粒;一次产卵量(F_b)在1997~6369粒之间, 平均为4114粒;体长相对繁殖力(F_L)在49~83粒/mm之间, 平均为62粒/mm;体质量相对繁殖力(F_W)在66~154粒/g之间, 平均为98粒/g。个体绝对繁殖力及一次产卵量与体长(L)呈幂函数相关, 与体质量(W)及净体质量(W_n)呈线性相关。相关回归式分别为:F=2.186L^1.6886 ;F_b =0.7243L^1.7796;F=50.184W + 3627.3;F_b=25.008W + 1952.2;F=58.783 W_n + 3553.4, F_b=28.939 W_n +1942。     

Calculation of vertical ground reaction force estimates during running from positional data

The purpose of this study was to calculate, as a function of time, segmental contributions to the vertical ground reaction force F_z from positional data for the landing phase in running. In order to evaluate the accuracy of the method, time histories of the sum of the segmental contributions were compared to F_z(t) measured directly by a force plate.

The human body was modeled as a system of seven rigid segments. During running the positions of markers defining these segments were monitored using a video analysis system operating at 200 Hz. Special care was taken to minimize marker movement relative to the mass centers of segments, and low-pass cutoff frequencies of 50 Hz (markers defining leg segments) and 15–20 Hz (markers defining upper body) were used in filtering the position time histories so as to ensure that high signal frequencies were preserved. The magnitude of the high-frequency peak in F_z, also known as ‘impact force peak’, was estimated with errors <10%, while the time of occurrence of the peak was estimated with errors <5 ms. It would appear that the positional data were sufficiently accurate to be used for calculation of intersegmental forces and moments during the landing phase in running.

Analysis of the segmental contributions to F_z(t) revealed that the first peak in F_z has its origin in the contribution of support leg segments, while its magnitude is determined primarily by the contribution of the rest of the body. These contributions could be varied independently by changing running style. It follows that if the possible relationship between ‘impact force peaks’ and injuries is to be investigated, or if the effects of running shoe and surface construction on these force peaks are to be evaluated, the calculation of segmental contributions to F_z(t) is a more suitable approach than measuring only F_z(t).     

Determination of effective diffusion coefficient of substrate in gel particles with immobilized biocatalyst

A method of determining of the effective diffusion coefficient of substrate in a particle, where the diffusion and consumption of substrate by biocatalytic reaction are present simultaneously, was designed and experimentally verified. The method is based on measuring the overall rate of heterogeneous biocatalytic reaction in particles of varying diameter. The effective diffusion coefficient, D_e, was determined by fitting the measured reaction rates with the solution of the reaction-diffusion equation. The method is tailored for cases where the enzyme reaction is governed by the Michaelis-Menten kinetics. The value of K_m required for the solution of the mathematical model was adopted from the measurement of the kinetics of free cells, whereas the rate parameter, k₂, was optimized together with D_e. As an experimental model, the sucrose hydrolysis catalyzed by Ca-alginate-entrapped yeast cells was examined. The particle diameter varied in the range of 1.2–3.9 mm and the initial reaction rates were measured in a batch-stirred reactor at a sucrose concentration of 100 m . The D_e of sucrose at 30°C was found to be 2.9 · 10⁻¹⁰ m²s⁻¹.     

Excitation spectra for Photosystem I and Photosystem II in chloroplasts and the spectral characteristics of the distribution of quanta between the two photosystems

The parameters listed in the title were determined within the context of a model for the photochemical apparatus of photosynthesis.

The fluorescence of variable yield at 750 nm at −196 °C is due to energy transfer from Photosystem II to Photosystem I. Fluorescence excitation spectra were measured at −196 °C at the minimum, F_O, level and the maximum, F_M, level of the emission at 750 nm. The difference spectrum, F_M–F_O, which represents the excitation spectrum for F_V is presented as a pure Photosystem II excitation spectrum. This spectrum shows a maximum at 677 nm, attributable to the antenna chlorophyll a of Photosystem II units, with a shoulder at 670 nm and a smaller maximum at 650 nm, presumably due to chlorophyll a and chlorophyll b of the light-harvesting chlorophyll complex.

Fluorescence at the F_O level at 750 nm can be considered in two parts; one part due to the fraction of absorbed quanta, , which excites Photosystem I more-or-less directly and another part due to energy transfer from Photosystem II to Photosystem I. The latter contribution can be estimated from the ratio of F_O/F_V measured at 692 nm and the extent of F_V at 750 nm. According to this procedure the excitation spectrum of Photosystem I at −196 °C was determined by subtracting 1/3 of the excitation spectrum of F_V at 750 nm from the excitation spectrum of F_O at 750 nm. The spectrum shows a relatively sharp maximum at 681 nm due to the antenna chlorophyll a of Photosystem I units with probably some energy transfer from the light-harvesting chlorophyll complex.

The wavelength dependence of was determined from fluorescence measurements at 692 and 750 nm at −196 °C. is constant to within a few percent from 400 to 680 nm, the maximum deviation being at 515 nm where shows a broad maximum increasing from 0.30 to 0.34. At wavelengths between 680 and 700 nm, increases to unity as Photosystem I becomes the dominant absorber in the photochemical apparatus.     

Fractal structure and conformational entropy of protein chain

The structures of 25 proteins arbitrarily chosen are investigated by fractal geometry, and their fractal dimensions (D_f) and conformational entropies S(N₀) are calculated by Havlin—Ben Avraham and Monte Carlo method, respectively. Comparison of the D_f and S(N₀) gives the relation: D_f = 1.532 - 3.00 × 10⁻⁴ S(N₀). The entropy data obtained by Monte Carlo method for the chain of random self-avoiding walks confirm the prediction of renormalization group: S(N₀) = 1.544N₀ + 0.1667 In N₀ + 0.1570 where N₀ is the number of residues in a protein chain. Both the D_f and S(N₀) reflect the conformational properties of a protein molecular chain. The idea resulting from the present communication suggests that the thermodynamic behaviours of proteins may be related to multifractals.     

基于SSR技术对黄河三角洲二色补血草遗传多样性研究

应用GENALEX6.502、ARLEQUINversion3.5、STRUCTUREv2.3.4、STRUCTURE Harvester、CLUMP和Distruct等软件进行遗传参数估算、主成分分析、遗传变异分析及遗传结构分析。在这项研究中,我们系统地从分布在中国黄河三角洲的12个二色补血草居群中采集到202份个体。我们通过使用共显性的微卫星标记探索微地理遗传结构,旨在解决黄河三角洲二色补血草居群结构和动态问题。结果表明：二色补血草呈中等程度的遗传分化,遗传变异主要存在于居群内,微弱的遗传分化存在于居群间,为（F_ST=0.067）。香农信息指数平均是1.037,基因流平均是4.106,观测杂合度和期望杂合度平均值分别是0.43和0.529。通过分析二色补血草群体的遗传多样性和遗传结构,旨在为资源的管理、保护和利用提供依据。总之,保护遗传多样性时,应保存尽可能多的居群和特异单株。     

A new technology of modulated Chl a fluorescence image: In vivo measurement of the PSII maximum photochemical efficiency and its heterogeneity within leaves

The spatial photosynthetic heterogeneity within leaves is an important prerequisite for the studies on the photosynthetic model, the mechanism(s) of photoinhibition and light protection, etc. However, currently the in vivo measurement of the spatial photosynthetic heterogeneity within leaves is difficult. The present study improved the device assembled by Vogelmann & Evans (2002), thereby acquired the photosystem II (PSII) maximum photochemical efficiency (F_v/F_m) images within leaves. Finally, these images were processed and data of F_v/F_m and its spatial variations could be obtained, with the aid of MATLAB software. Based on the innovative technique, an investigation of the effects of strong light on the F_v/F_m and its spatial heterogeneity within leaves has been carried out. It was found that F_v/F_m within leaves was not homogonous. Strong light led to a general decrease of F_v/F_m (PSII photoinhibition) across leaf section, and the palisade tissue close to the epidermis layer had high tolerance to photoinhibition. Compared with control, short-term photoinhibition caused a larger spatial variation of F_v/F_m within leaves, which may be related to the chloroplast-avoidance response induced by high-fluence. On the contrary, long-term light inhibition led to a smaller spatial variation of F_v/F_m within leaves, indicating such mechanism is no longer effective. Compared to other types of chlorophyll fluoremeter, the device in the present study can in vivo obtain the panoramic picture of F_v/F_m within leaves, providing a powerful tool for the studies on the mechanism(s) attributed to the spatial heterogeneity of photosynthetic capacity of leaf, which is critical for the understanding on several hot spots in the research field of photosynthesis.