Volubolin,a 4-phenyl-2H-1-benzopyran-2-one from Dalbergia volubilis

From the ether soluble portion of a methanolic extract of young non-green branches of Dalbergia volubilis, sitosterol, 7-hydroxy-4-methyl-2H-1-benz     

Seasonal changes in the Modulus of Elasticity of living branches of three coniferous species

The seasonal changes in the Modulus of Elasticity (E) of living branches ofCryptomeria japonica, Chamaecyparis obtusa andLarix leptolepis were investigated over a period of 1 year by means of a quick and non-destructive method previously introduced by the authors. Two sample trees were used for each species and 12 branches were selected from each tree. Readings of the experiments began in summer 1992 and were successively conducted in autumn 1992, winter 1993, spring 1993 and finally in summer 1993. Our investigations revealed that meanE values increased in cold seasons and decreased in warm or hot seasons. Mean values ofE estimated in summer (1993) were relatively close to those estimated in summer 1992 indicating that any changes that occurred were the direct result of the environmental factors prevailing in the intervening seasons. Extremely high meanE values were measured when the branches were in a frozen state in winter; 69.4%, 29.9% and 24.6% higher than the previous summer for branches ofCryptomeria japonica, Chamaecyparis obtusa andLarix leptolepis, respectively. This sharp increase over the initialE values measured in summer 1992 was quite likely due to the freezing effect of rime on the branches.     

Comparative phenological and water potential patterns of three Calligonum species in the eastern great Erg of Tunisia

Calligonum azel, C. comosum and C. arich (Polygonaceae) are three dominant and economically important species widely distributed in active sand dunes in the southern desert of Tunisia, which differ in growth form and may co-occur under the same climatic constraints. The aims of this work were to compare their phenological and water potential patterns, as well as branch, flower and fruit production during three years at monthly intervals. Predawn (Ψ_pd) and midday (Ψ_md) water potentials followed similar trends with a few exceptions. For all species, Ψ_md reached values more negative than −2.5 MPa during the hot and dry summer, with extremes in July. Ψ_pd differed between the species, and C. comosum attained the most negative values (−1.71 MPa). Seasonal differences in Ψ_pd were less pronounced for Calligonum species established in dunes as compared to C. comosum from interdunes. Spatial and temporal variations in soil water content provoked changes in water potentials of these species. Diurnal amplitudes resulting from the difference between Ψ_md and Ψ_pd were more pronounced during the dry season compared to the wet months. The phenological pattern of the three species showed a similar sequence of phenophases with growth activity occurring mostly between spring and summer. We found a species-dependent response to summer drought, as C. comosum ended all phenophases in June, while C. azel and C. arich extended their vegetative growth into the summer period of low precipitation. Water availability for the plants was better on the dune slopes. Differences were statistically significant among species, concerning green branch production and numbers of initially formed flowers and mature fruits. Our data suggest that changes in the studied parameters may depend on the rooting depth of the species.     

大兴安岭地区笃斯越橘基生枝条矿质养分特性

以大兴安岭地区3种主要立地类型的笃斯越橘为试验材料,通过分析由灌丛基部萌生的1~2年生(S1)、3年生(S2)、4年生(S3)、5年生(S4)、趋于衰老的多年生(S5)枝条叶片和茎部,以及衰老枝条(S6)的N、P、K、Ca、Mg、Mn含量分布规律及其与新梢生长的关系,明确矿质元素在笃斯越橘不同年龄基生枝上叶片及茎部的分布特性,探索矿质营养与笃斯越橘树体生长发育及衰老更新的关系。结果表明:(1)6种元素在不同年龄枝条分布呈现不同的规律,其中,N、P、K随基生枝条年龄增加大致呈下降趋势,叶片和茎部分别在S5、S6时期降到最小值;Ca在衰老枝条上含量最高,Mg元素在S1时期叶片上分布较高;Mn在不同年龄基生枝中波动较小,水湿地、山地类型叶片Mn元素随枝龄增加而提高,茎部则先增后减,在S5时期分布最高;N、P、K、Ca、Mg含量表现为叶片明显高于茎部,而塔头草甸类型茎部Mn略高于叶片,且茎部Mn含量高达2 000mg·kg~(-1)。(2)笃斯越橘的新梢生长量与叶片K、Mg以及茎部N、K、Mg含量呈极显著正相关关系,与叶片Ca、Mn以及茎部Ca含量呈显著或极显著负相关关系。(3)典型相关分析结果显示,影响笃斯越橘新梢生长量的矿质元素因子因基生枝条年龄而异;S1时期主要与叶片Mg含量有关,S2~S4阶段受茎部K、Ca、Mg影响最大,S5时期主要受叶片Ca含量影响。(4)笃斯越橘的衰老可能与Ca积累有关。     

Intriguing asexual life in marginal populations of the brown seaweed Fucus vesiculosus

Reproduction of attached large brown algae is known to occur only by sexual zygotes. Using microsatellites we show evolution of asexual reproduction in the bladder wrack promoting population persistence in the brackish water Baltic Sea (< 6 psu). Here a dwarf morph of Fucus vesiculosus is dominated by a single clone but clonal reproduction is also present in the common form of the species. We describe a possible mechanism for vegetative reproduction of attached algae, and conclude that clonality plays an important role in persistence and dispersal of these marginal populations, in which sexual reproduction is impaired by low salinity.     

A role for Fas II in the stabilization of motor neuron branches during pruning in Drosophila

During insect metamorphosis, the nervous system is extensively remodeled resulting in the development of new circuits that will execute adult-specific behaviors. The peripheral remodeling seen during development of innervation to the Dorsal Longitudinal (flight) Muscle (DLM) in Drosophila involves an initial retraction of larval neuromuscular junctions followed by adult-specific branch outgrowth. Subsequently, a phase of pruning occurs during which motor neuron branches are pruned back to reveal the stereotypic pattern of multiple contact points (or arbors) along the length of each DLM fiber. In this study, we show that the cell adhesion molecule, Fasciclin II (Fas II), is important for generating the stereotypic pattern. In Fas II hypomorphs, the number of contact points is increased, and the phenotype is rescued by targeted expression of Fas II in either synaptic partner. Arbor development has three distinct phases: outgrowth and elaboration, pruning and stabilization, and expansion of stabilized arbors. Fas II is expressed during the first two phases. A subset of branches is labeled during the elaboration phase, which is likely to initiate a stabilization pathway allowing branches to survive the pruning phase. However, since not all Fas II positive branches are retained, we propose that it primes branches for stabilization. Our data suggest that Fas II functions to restrict branch length and arbor expanse.     

藿香枝叶多糖的提取工艺及其清除羟基自由基作用研究

采用苯酚-硫酸,并以超声法辅助提取野生藿香枝叶中的多糖,设计L9(34)正交试验考察料液比、pH和超声提取时间对藿香枝叶中多糖提取的影响,并对藿香多糖进行清除.OH试验。结果表明,藿香多糖的最佳提取工艺为料液比1∶10,超声提取30min,pH值为6,可使藿香多糖的提取率高达7.50%。藿香多糖对羟基自由基有显著地清除效果,表明其有抗氧化作用。     

Intra-specific hybridization: generator of genetic diversification and heterosis in Andrographis paniculata Nees. A bridge from extinction to survival

Andrographis paniculata (AP) has been stated as a low-diverse, endangered and red-listed plant species. Self-pollinated mating system, being an introduced species and experiencing a bottleneck as well as over exploitation cause such a consequence. Inter and intra-specific hybridizations have been suggested as essential techniques for generating genetic diversity. To test the effect of intra-specific hybridization on diversification and heterosis of AP, seven accessions were outcrossed manually in all 21 possible combinations. Three types of markers including morphological, phytochemical and RAPD markers were employed to evaluate the mentioned hypothesis. The results revealed that hybridization acted as a powerful engine for diversification of AP as it caused heterotic expression of the studied traits, simultaneously. Initially, it seems that additive and non-additive gene effects both can be considered as the genetic basis of heterosis in AP for the investigated traits. Agronomic and morphological traits were differentiated from each other, while positive heterosis was recorded mainly for agronomic traits but not for the morphological traits. Intra-specific hybridization increased the genetic diversity in AP population. Nevertheless, a part of this variation could also be attributed to the negative heterosis. The current exploration demonstrated the first ever conducted manual intra-specific hybridization among AP accessions in a mass scale. However, the 17 RAPD primers produced a monomorph pattern, but perhaps increasing the number of markers can feature a new genetic profile in this plant.     

不同灌溉量对头状沙拐枣幼苗生长和生理特性的影响

采用盆栽试验,分析了不同水分梯度下(田间持水量的30%、40%、50%、60%和85%)头状沙拐枣幼苗的干物质累积分配特征及生理生化特性,以探明头状沙拐枣幼苗能够良好生长的土壤水分条件。结果表明:(1)随灌溉量增加,沙拐枣幼苗同化枝的干物质累积量显著增加,但在最高灌溉量下同化枝出现严重病害。(2)在生长旺季,增加灌溉量后,同化枝的干物质分配比例也均显著增加,平均可占整株的39.5%;季末,分配比例受灌溉量的影响明显减弱,平均占整株的12.3%。(3)在整个生长季同化枝的全氮和硝态氮含量均处于较高水平,随灌溉量增加全氮含量有降低趋势,硝态氮含量则波动变化。(4)灌溉量对植株同化枝生理特性的影响主要表现在生长旺季。在最低灌溉量下,同化枝丙二醛含量明显较高,但植物可通过大量累积脯氨酸和可溶性糖来降低体内水势,以提高植物抗旱性;在最高和最低灌溉量下,同化枝硝酸还原酶活性和叶绿素含量均显著下降。研究认为,沙拐枣幼苗虽具有较强的抗旱性,但灌溉量过低或过高对同化枝的生长、氮素还原和叶绿素累积均有明显的抑制,因此中等灌溉量(田间持水量的50%~60%)对头状沙拐枣幼苗生长更有利。