Verbascoside isolated from Tectona grandis mediates gastric protection in rats via inhibiting proton pump activity

Evidences have suggested that Tectona grandis (TG) attenuates gastric mucosal injury; however its mechanism has not yet been established. The aim of present study was to evaluate the gastroprotective mechanism of ethanolic extract of TG (E-EtOH), butanolic fraction (Fr-Bu) and to identify its active constituents. Anti-ulcer activities were evaluated against cold restraint (CRU) and pyloric ligation (PL) induced gastric ulcer models and further confirmed through H⁺ K⁺-ATPase inhibitory activity. Cytoprotective activity was evaluated in alcohol (AL) induced gastric ulcer model and further through PGE₂ level. E-EtOH and Fr-Bu attenuated ulcer formation in CRU. Moreover E-EtOH and Fr-Bu displayed potent anti-secretory activity as evident through reduced free acidity and pepsin activity in PL, confirmed further by in vitro inhibition of H⁺ K⁺-ATPase activity. In addition cytoprotective potential of E-EtOH and Fr-Bu were apparent with protection in AL model, increased PGE₂ content and enhanced mucin level in PL. Phytochemical investigations of Fr-Bu yielded terpenoides and a phenolic glycoside, verbascoside. The anti-secretory mechanism of verbascoside mediated apparently through inhibition of H⁺ K⁺-ATPase with corresponding decrease in plasma gastrin level, is novel to our finding. Gastroprotection elicited by TG might be through proton pump inhibition and consequent augmentation of the defensive mechanism.     

Transfer characteristics of nutrient elements through hydrological process of a Pinus tabulaeformis stand in the West Mountain of Beijing

Forest precipitation chemistry is a major issue in forest hydrology and forest ecology. Chemical contents in precipitation change significantly when different kinds of external chemical materials are added, removed, translocated and transformed to or in the forest ecosystem along with precipitation. The chemistry of precipitation was monitored and analyzed in a 31-year-old Pinus tabulaeformis forest in the West Mountain of Beijing. Movement patterns of nutrient elements in hydrological processes can be discovered by studying this monitored data. Also, the information is useful for diagnosing the function of ecosystems and evaluating the impact of the environment on the ecosystem. Samples of rainfall, throughfall and stemflow were collected on the site. In the lab, Ca²⁺ and Mg²⁺ were analyzed by flame atomic absorption and K⁺ and Na⁺ by flame emission. NH₄ ⁺-N was analyzed by indophenol blue colorimetry and NO₃ ⁻-N was analyzed by phenoldisulfonic acid colorimetry. The results showed that: 1) The concentration gradient of nutrient elements clearly changed except for Na⁺. The nutrients in stemflow were significantly higher than those of throughfall and rainfall as the precipitation passed through the P. tabulaeformis forest. The monthly patterns showed distinct differentiation. There are indications that a large amount of nutrients was leached from the canopy, which is a critical function of intra-ecosystem nutrient cycling to improve the efficiency of nutrient use. 2) The concentrations of NO₃ ⁻-N and K⁺ changed more than those of the other nutrient elements. The concentration of NO₃ ⁻-N in throughfall and stemflow was 4.4 times and 9.9 times higher than those in rainfall, respectively. The concentration of K⁺ in throughfall and stemflow was 4.1 times and 8.1 times higher than those in rainfall, respectively. 3) The leaching of nutrient elements from the stand was an important aspect of nutrient return to the P. tabulaeformis forest, which returned a total amount of nutrient of 54.1 kg/hm², with the contribution of Ca²⁺ and K⁺ much greater than that of other elements. Also, K⁺ was the most active element in leaching intensity. 4) Nutrient input through precipitation was the main source in the West Mountain of Beijing and the amount of nutrient added was 66.4 kg/hm², of which Ca²⁺ and N contributed much more than the other nutrient elements. When precipitation passes through the P. tabulaeformis forest, 121 kg/hm² of nutrient is added to the forest floor. Ca²⁺ recorded the greatest nutrient increase, with 61.2 kg/hm², followed by N (NH₄ ⁺-N and NO₃ ⁻-N), K⁺ and Mg²⁺, with 31.3 and 16.5, and 8.11 kg/hm², respectively. The least was Na⁺, 3.34 kg/hm². Translated from Acta Ecologica Sinica, 2006, 26(7): 2,101–2,107 [译自: 生态学报]     

广州市酸雨对不同森林冠层淋溶规律的研究

１９９８年４月至１９９９年３月对广州市白云山马尾松林和常绿阔叶林、广州市龙眼洞马尾松林两试验点进行了酸雨的监测,并测定和分析了林内穿透雨物理量及化学量,旨在探讨酸雨对不同森林冠层养分淋溶规律的影响。结果表明：（１）广州市酸雨占次数的７９．７％或占降雨量的９５．１％。（２）酸雨通过林冠层后,ｐＨ值明显增加。（３）在马尾松林和常绿阔叶林中,某些单次降雨出现ＳＯ４＾２－、ＮＯ３＾－、ＮＨ４＾＋Ａｌ＾３＋、Ｎａ＾＋的负淋溶现象,说明森林对这些离子（特别是ＮＯ３＾－、Ａａ＾３＋）具有吸收作用;阔叶林全年的ＮＯ３＾－和Ａｌ＾３＋净淋溶为负值,说明阔叶林比马尾松林对这两种离子具有更强的吸收能力。（４）雨水酸度增加（即ｐＨ值减小）,明显提高阳离子Ｃａ＾２＋、Ｍｇ＾２＋、Ｋ＾＋和Ｎａ＾＋冠层淋溶面分率。（５）ＮＨ４＾＋、ＳＯ４＾     

Spice oil cinnamaldehyde exhibits potent anticandidal activity against fluconazole resistant clinical isolates

Fluconazole resistance is becoming an important clinical concern. We studied the in vitro effects of cinnamaldehyde against 18 fluconazole-resistant Candida isolates. MIC₉₀ of cinnamaldehyde against different Candida isolates ranged 100–500 μg/ml. Growth and sensitivity of the organisms were significantly affected by cinnamaldehyde at different concentrations. The rapid irreversible action of this compound on fungal cells suggested membrane-located targets for its action. Insight studies to mechanism suggested that cinnamaldehyde exerts its antifungal activity by targeting sterol biosynthesis and plasma membrane ATPase activity. Inhibition of H⁺-ATPase leads to intracellular acidification and cell death. Toxicity against H9c2 rat cardiac myoblasts was studied to exclude the possibility of further associated cytotoxicity. The observed selectively fungicidal characteristics against fluconazole-resistant Candida isolates signify a promising candidature of this essential oil as an antifungal agent in treatments for candidosis.     

Nutrient element contents of cutting seedlings of hybrid species （ Liriodendron chinense x tulipifera）

The cutting seedlings ofLiriodendron chinense xtulipifera were treated with the different concentrations of auxin (treatment₁: IBA of 50 g·kg⁻¹+NAA of 300 g·kg⁻¹; treatment₂; IBA of 100 g·kg⁻¹+NAA of 300 g·kg⁻¹). The biomass nutrient element contents for different organs (root, stem, leaf) of cutting seedling ofLiriodendron chinense xtulipifera were measured by the dry method, Kjeldahl method and Atomic Absorption Spectroscopy method. The result showed that the biomass of root, stem, and leaf of the cutting seedling treated with auxin was all remarkably increased. The contents of element C in root, stem and leaf had no significant difference between the control and auxin treatments, while the contents of N, P, K and Ca in stem were much lower than that in leaf and root. Variance analysis showed that for the same organ with different concentration treatment of auxin, the four nutrient elements (N, P, K, and Ca) had no significant difference in contents, while there existed significant or very significant difference in contents of the four nutrient elements in different organs with the same concentration auxin treatment. The N, P, K and Ca contents were very low in cutting seedlings; as a result, additional fertilizer should be applied to the seedlings when they were planted in the field. Foundation item: This paper was supported by Jiangsu Province Science Foundation (BE96350). Biography: ZHANG Xiao-ping, (1972-), female, Ph. Doctor in Nanjing Forestry University. Nanjing 210037, P. R. China. Responsible editor: Zhu Hong     

C2H2-reduction byErythrina poeppigiana in a Costa Rican coffee plantation

Acetylene reduction activity by root nodules of the legumeErythrina poeppigiana, growing as shade tree in a Costa Rican coffee plantation, was estimated. The mean activity found was 15.7 nmole C₂H₄ · mg (dry weight)^–1 · h^–1. Root nodules collected at different distances from theErythrina stem showed the same activity per dry weight unit. However, as the biomass of the nodules was highest near the stem, was the acetylene reduction activity (expressed per soil volume) maximal near theErythrina stem and declined with distance.     

Diversity and bioactivity of bacterial endophyte community of Cupressaceae

The plant family Cupressaceae (Coniferales) harbours diverse endophytic fungi with antifungal, antibacterial and antiproliferative activities. Here, endophytic association of a broad bacterial community with the healthy foliar tissues of Cupressus arizonica, Cupressus sempervirens, Juniperus communis and Thuja orientalis (Cupressaceae) is shown. We isolated over 69 endophytic bacterial strains of Proteobacteria, Bacilli and Actinobacteria from Cupressaceae. The initial screening for antifungal activity against Pyricularia oryzae identified eleven superior bacterial strains which were identified as Brevundimonas diminuta CAE₂₄ (G^?, Caulobacteraceae, Alphaproteobacteria); Stenotrophomonas maltophilia CAE₂₃, CSE₄, CSE₁₂, CSE₄₂, CSE₄₉ and CSE₆₂ (G^?, Xanthomonadaceae, Gammaproteobacteria); Bacillus pumilus CSE₆₆ and Bacillus subtilis POE₂₆ (G⁺, Bacillaceae, Bacilli); and Microbacterium resistens CSE₁₉ (G⁺, Microbacteriaceae, Actinobacteria). The dominant isolated bacterial species was S. maltophilia. This species represented 63.6% of the superior strains which was ubiquitous and also non‐host specific. In addition, the superior bacterial strains produced bioactive secondary metabolites and volatile compounds (VOCs) with antifungal activity against the fungal pathogens of Cupressaceae, that is Diplodia seriata, Phaeobotryon cupressi and Spencermartinsia viticola. The antagonistic activity of the endophytic bacteria on the target fungi was also confirmed in vitro. To our knowledge, this is the first to document such an endophytic bacterial community in Cupressaceae and its bioactivity. These findings may find application in organic agroforestry for plant disease biocontrol and in biopharmacy for lead molecule discovery.     

Effects of elevated CO2 concentrations on photosynthesis, dark respiration and RuBPcase activity of three species seedlings in Changbai Mountain

Two-year-old seedlings ofPinus koraiensis, Pinus sylvestriformis andFraxinus mandshurica were treated in open-top chambers with elevated CO₂ concentrations (700 μL·L⁻¹, 500 μL·L⁻¹) and ambient CO₂ concentrations (350 μL·L⁻¹) in Changbai Mountain from June to Sept. in 1999 and 2001. The net photosynthetic rate, dark respiration rate, ribulose-1,5-bisphosphate carboxlase (RuBPcase) activity, and chlorophyll content were analyzed. The results indicated the RuBPcase activity of the three species seedlings increased at elevated CO₂ concentrations. The elevated CO₂ concentrations stimulated the net photosynthetic rates of three tree species exceptP. sylvestriformis grown under 500 μL·L⁻¹ CO₂ concentration. The dark respiration rates ofP. koraiensis andP. sylvestriformis increased under concentration of 700 μL·L⁻¹ CO₂, out that ofF. mandshurica decreased under both concentrations 700 μL·L⁻¹ and 500 μL·L⁻¹ CO₂. The seedlings ofF. mandshurica decreased in chlorophyll contents at elevated CO₂ concentrations. Foundation item: This paper was supported by the National Natural Science Foundation of China (No. 30070158). Knowledge Innovation Item of Chinese Academy of Sciences (KZCX2-406) and “Hundred Scientists” Project of Chinese Academy of Sciences. Biography: Zhou Yu-mei (1973-) Ph. Doctor, Assistant Research fellow Institute of Applied Ecology. Chinese Academy of Sciences. Shenyang 110016. P.R. China. Responsible editor: Song Funan     

Utility of multivariate analyses in examining foliage composition and soil nutrition in a factorial fertilizer experiment

The data for this paper were derived from a previously reported field trial with Pinus radiata which was treated with fertilizer at planting and three subsequent occasions. The experiment tested factorial combinations of urea (n), dicalcium phosphate (p), gypsum (s) and potassium chloride plus trace elements (b).At 5 years-of-age bole development was substantially increased by p alone, but p and n in combination increased growth further still. Urea, applied alone, had no, or retardive effects. Foliage concentrations of N, P, K, Ca, Mg, Fe and Mn were raised by p or n and p in combination, but Zn concentrations were not changed. Urea alone caused significantly lower Fe, Mg, Ca, and K concentrations in foliage.The 16 fertilizer combinations created a series of diverse soil nutrient conditions. For the ameliorative treatments (p and np), soils were characterized by high levels of total P and N, and exchangeable NH ₄ ⁺ and Ca ²⁺ whereas soils treated with n alone had low levels of the cations Mg²⁺, Ca²⁺, and Na⁺, but higher A1³⁺. While not contributing to stem growth, the s and b treatments also formed unique soil nutrient concentrations; s induced appreciable increases in Ca²⁺ while b resulted in a 3.5-fold increase in K⁺.Multivariate statistical analyses aided examination of the experimental data, whereas univariate analyses became cumbersome or repetitive, or gave no insight into individual contributions to overall variation. Eigenvalues extracted from discriminant analyses did provide this information, and ranked effects in order of importance. The effects of urea fertilizer on concentration of a number of elements in the foliage and on soil nutrient status were small but had marked effects on growth. It is envisaged that multivariate techniques can be utilized with other trial data, provided such experiments are soundly designed and adequately replicated.     

短期NaCl胁迫对西伯利亚白刺幼苗Na~+、K~+分配和平衡的影响

[目的]为探究西伯利亚白刺盐适应机制。[方法]以1年生西伯利亚白刺水培幼苗为材料,研究不同浓度NaCl(0、200、300 mmol·L-1)胁迫24 h后根系Na~+、K~+离子流的动态变化(利用扫描离子选择微电极技术,SIET)及植株各器官中Na~+、K~+含量的静态变化(利用电感耦合等离子体光谱仪,ICP-OES)。[结果]表明:(1)短期NaCl胁迫显著提高了西伯利亚白刺根、茎、叶中Na~+含量,其中,叶中Na~+含量是根中的3倍以上;西伯利亚白刺根、茎、叶中K~+含量保持稳定或上升;(2)盐胁迫下,西伯利亚白刺根、茎、叶中K~+/Na~+呈下降趋势,其中,在200、300 mmol·L-1NaCl胁迫下,根中K~+/Na~+差异不显著;(3)离子流结果显示,NaCl胁迫显著提高了西伯利亚白刺根系Na~+的外流;对照和200 mmol·L-1NaCl胁迫下,K~+净流量分别为156、159 pmol·cm-2·s-1,差异不显著;300 mmol·L-1NaCl胁迫显著提高了K~+的内流,净流量为-370 pmol·cm-2·s-1。[结论]综合分析认为,西伯利亚白刺通过叶片对Na~+区隔,加强根系对Na~+的外排和K~+内流,进而维持植株根系K~+/Na~+的相对平衡,以此适应盐渍环境。     

NaCl胁迫下沙枣幼苗的离子代谢特性

[Objective]To further understand the ion metabolism characteristics of Elaeagnus angustifolia L. under NaCl stress.[Method]The seedlings of two E. angustifolia L. provenances, which were Alaer (salt tolerance provenance) and Yinchuan (salt sensitive provenance), were treated by three NaCl concentrations (0,150,300 mmol·L^-1) and sampled at the 7th day and the 30th day to measure the Na⁺ , K⁺, Ca²⁺, and Mg²⁺ contents, K⁺/Na⁺ ratio and selective absorption and transportation of K⁺ in tissues (roots, stems and leaves). [Result]The results showed that the Na⁺ content in the organizations of E. angustifolia L. sharply increased with the increase of NaCl concentration. With prolonging of stress time, the Na⁺ content increased in roots, and decreased in stems and leaves. After seedlings of the two provenances were treated with 150 mmol·L^-1 NaCl for 7 days, the Na⁺ content was 2.10 times and 2.23 times in leaves, respectively, compared with the control groups, and was 1.79 times and 1.57 times in root. Meanwhile, the difference between two provenances showed a expanding trend with the increase of NaCl concentration and stress time. With the increase of NaCl concentration and extension of stress time, the K⁺ content, Ca²⁺ content and K⁺/Na⁺ ratio in organizations decreased gradually. Meanwhile, the Alaer provenance seedlings accumulated more Na⁺ in roots and less Na⁺ in leaves than that of Yinchuan provenance, and the K⁺ content, Ca²⁺ content and K⁺/Na⁺ ratio decreased less in the Alaer provenance seedlings than those of Yinchuan provenance. With the increase of NaCl concentration, the Mg²⁺ content in leaf gradually decrease, but the Mg²⁺ content in root increased 22.8~64.4% after salt stress for 7 days, and Alaer provenance seedlings increased more than Yinchuan provenance. After 30 days, there was non-significant difference with the control group on the Mg²⁺ content of root. K⁺ selective absorption of E. angustifolia L. seedlings significantly increased with increasing salt concentration of the media at the 7th days, whereas not obvious at the 30th days. When the concentration of NaCl in the media increased, the change of K⁺ selective transportation was not significant. [Conclusion]E. angustifolia L. seedlings increase Mg²⁺ content and K⁺ selective absorption in the roots at the early stage of salt stress to adapt saline environment. The salt-tolerance E. angustifolia L. provenance can cut off more Na⁺ in roots and reduce Na⁺ content in leaves, which cause less K⁺, Ca²⁺ and Mg²⁺ contents loss, especially the roots and leaves, so as to ensure that all kinds of metabolisms can go well.     

Characterization and role of glucose-6-phosphate dehydrogenase of Populus suaveolens in induction of freezing resistance

Glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) was purified from the leaves of 8-week-old Populus suaveolens cuttings. The enzyme activity in the absence and presence of reduced dithiothreitol (DTT_red) was determined. The results show that the G6PDH activity is not inactivated by pre-incubation with DTT_red, indicating that the purified enzyme probably presented in cytosol of P. suaveolens. The catalytic characteristics and kinetic parameters of cytosolic G6PDH purified from P. suaveolens cuttings were also studied. The results show that G6PDH is characterized by K _m value of 360 μmol·L⁻¹ for G6P and 16 μmol·L⁻¹ for NADP, a pH range of 7.3-8.9, and the maximum activity around pH 8.2. The enzyme activity is inhibited by various metabolites such as NADPH, NADH, GTP, UTP, ATP, AMP, ADP, CoA, acetyl CoA, fructose-6-phosphate (F6P), erythrose-4-phosphate (E4P), ribose-5-phosphate (R5P) and 3-phosphoglycerate (3-PG) (all at 1 mmol·L⁻¹ except for NADPH and NADH) to different extents. NADPH is the most effective inhibitor of enzyme activity, with an inhibition of 72.0%. The addition of metal ions such as MgCl₂, CaCl₂ and KCl (all 1.0 mmol·L⁻¹) to the standard reaction mixture has no remarkable influence on the cytosolic G6PDH activity. However, CdCl₂ (1.0 mmol·L⁻¹) causes high inhibitory effect on the enzyme activity. To explore the role of G6PDH on the enhancement of freezing resistance induced by freezing acclimation, the changes in the cytosolic G6PDH activity and freezing resistance (expressed as LT₅₀) of P. suaveolens cuttings during freezing acclimation at −20 °C were investigated. The results reveal that freezing acclimation decreases LT₅₀ of cuttings, and increases the activity of cytosolic G6PDH compared with control ones, while 2 d of de-acclimation at 25 °C result in a decrease in cytosolic G6PDH activity, and caused an increase in LT₅₀. Furthermore, the change in cytosolic G6PDH activity is found to be closely correlated to the degree of freezing resistance of cuttings during freezing acclimation. It is suggested that cytosolic G6PDH may be involved in the induction of freezing resistance of cuttings. [Supported by the Foundation of State-designated Base for Biology Researching and Teaching in Beijing Forestry University]     

Growth and physiological responses of chestnut calli to crude extracts of virulent and hypovirulent strains of Cryphonectria parasitica

The effect of crude extracts (CEs) of virulent (V‐E4) and hypovirulent (H‐E13) Cryphonectria parasitica strains on growth and physiological activities of chestnut calli was investigated on cell cultures obtained from either a susceptible Castanea sativa or a resistant Castanea mollissima chestnut species. The V‐E4 CEs significantly reduced calli fresh weight in both species when used at 50 and 500 μg g^–1 and, in general, showed an inhibitory effect on either O₂ uptake and H⁺‐ATPase activity. Only the highest (500 μg g^–1) concentration of H‐E13 CEs had a detrimental effect on callus growth, whereas the lowest one (5 μg g^–1) induced a slight, but significant early increase in callus fresh weight of both genotypes. The O₂ uptake and H⁺‐ATPase activity were enhanced by the presence of H‐E13 CEs. The decrease of callus growth and physiological activities, caused by V‐E4 CEs, was attributed to toxic compounds produced by the C. parasitica virulent strain, whereas the stimulatory effects of H‐E13 CEs on the overall callus metabolism seemed to be due either to the lack or very reduced amount of phytotoxic compounds and to growth‐regulating substances produced only by the hypovirulent strain of the fungus.     

Dissolved organic carbon and nitrogen in precipitation, throughfall and stemflow fromSchima superba andCunninghamia lanceolata plantations in subtropical China

Despite growing attention to the role of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in forest nutrient cycling, their monthly concentration dynamics in forest ecosystems, especially in subtropical forests only were little known. The goal of this study is to measure the concentrations and monthly dynamics of DOC and DON in precipitation, throughfall and stemflow for two plantations ofSchima superba (SS) and Chinese fir (Cunninghamia lanceolata, CF) in Jianou, Fujian, China. Samples of precipitation, throughfall and stemflow were collected on a rain event base from January 2002 to December 2002. Upon collection, all water samples were analyzed for DOC, NO₃ ⁻−N, NH₄ ⁺−N and total dissolved N (TDN). DON was calculated by subtracting NO₃ ⁻−N and NH₄ ⁺−N from TDN. The results showed that the precipitation had a mean DOC concentration of 1.7 mg·L⁻¹ and DON concentration of 0.13 mg·L⁻¹. The mean DOC and DON concentrations in throughfall were 11.2 and 0.24 mg·L⁻¹ in the SS and 10.3 and 0.19 mg·L⁻¹ in the CF respectively. Stemflow DOC and DON concentrations in the CF (19.1 and 0.66 mg·L⁻¹ respectively) were significantly higher than those in the SS (17.6 and 0.48 mg·L⁻¹ respectively). No clear monthly variation in precipitation DOC concentration was found in our study, while DON concentration in precipitation tended to be higher in summer or autumn. The monthly variations of DON concentrations were very similar in throughfall and stemflow at both forests, showing an increase at the beginning of the rainy season in March. In contrast, monthly changes of the DOC concentrations in throughfall of the SS and CF were different to those in stemflow. Throughfall DOC concentrations were higher from February to April, while relatively higher DOC concentrations in stemflow were found during September–November period. Foundation item: This study was supported by the Teaching and Research Award program for MOE P.R.C. (TRAPOYT). Biography: Guo Jian-fen (1977-), female, Ph. Doctor in College of Life Science, Xiamen University, Xiamen 361005, P.R. China. Responsible editor: Zhu Hong     

Capacity of stem water conductivity for two eucalyptus ( Eucalyptus urophylla ) plantations in South China

The sap flux density (SFD) was used as a measure of water capacity through stems of eucalyptus in this paper. It was found that daily SFD increased with daily vapor pressure deficit (VPD) in nonlinear regression Y=AX ³+BX ²+CX+D (R ²=0.702 1, n=135, p=0.01) at both sites (Hetou and Jijia) in the Leizhou Peninsula, Guangdong Province, China, where Y was daily SFD, X was mean daily VPD, A, B, C, D were constants. But extremely high VPD might limit stem water conductivity. The environmental factors, such as air vapor pressure deficit (VPD), solar radiation (RAD), etc., were the main determinants of SFD for E. urophylla plantations. The upper threshold of diurnal SFD was 51.55–55.65 mL·cm⁻²·h⁻¹ under the selected extremely high environmental conditions.     

A laboratory study on the activity of <Emphasis Type="Italic">Steinernema feltiae</Emphasis> (Rhabditida: Steinernematidae) Rioja strain against horticultural insect pests

The potential of the entomopathogenic nematode Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) Rioja strain was assessed under laboratory conditions. Last instar larvae of Leptinotarsa decemlineata Say (Coleptera: Chrysomelidae), Spodoptera littoralis Boisdouval (Lepidoptera: Noctuidae) and Trichoplusia ni Hübner (Lepidoptera: Noctuidae) were exposed to infective juveniles (IJs) under laboratory conditions. Larval mortality, days to larval death, infection cycle length, and reproductive potential were recorded. Efficacy was assessed performing dose–response experiments. The results indicate that control of L. decemlineata with S. feltiae Rioja strain is not economically profitable (LC₅₀ = 99.61 IJs/cm²), whereas results obtained for T. ni (LC₅₀ = 0.27 IJs/cm²) are promising. Due to the life cycle of this insect, the efficacy needs to be investigated in foliar application studies. The effects on S. littoralis (LC₅₀ = 0.69 IJs/cm²) was considered the most suitable for development of the Rioja strain as a biocontrol agent for soil application.     

Effect of NaCl stress on ion distribution in roots and growth of Cyclocarya paliurus seedlings

We studied ion distribution in roots and the growth of Cyclocarya paliurus seedlings of three provenances, Huangshan in Anhui, Jiujiang in Jiangxi and Kunming in Yunnan, under conditions of 0, 1, 3 and 5 g/L NaCl stress using X-ray microanalysis. Results show that under NaCl stress of 3 and 5 g/L, the relative contents of Na⁺ and Cl⁻ in root tissues increased, while the relative contents of K⁺, Ca²⁺ and Mg²⁺ decreased. With an increase in salinity, the relative content of Na⁺ in the epidermis and cortex of the root increased, while the relative content of Cl⁻ in the stele and cortex of the root increased markedly. Thus, ions in the root tissues were unbalanced and the ratios K⁺/Na⁺ and Ca²⁺/Na⁺ decreased, while Na⁺/(K⁺+ Na⁺+Ca²⁺+Mg²⁺) increased. The decrease of the K⁺/Na⁺ ratio and the substantial increase of Cl⁻ in root tissues contributed to a decline in seedlings survival and reduced the increments for seedling leaf area, height, basal diameter as well biomass. Our preliminary conclusion is that the level of salt tolerance for the tested provenance seedlings was in the order of Huangshan > Kunming > Jiujiang, and the threshold of salt tolerance for C. paliurus seedlings was about 1 g/L. __________ Translated from Scientia Silvae Sinica, 2008, 44(6): 66–72 [틫自: 쇖튵뿆톧]     

降雨特征对兴安落叶松林降雨再分配过程中钾元素影响分析

[目的]以大兴安岭地区兴安落叶松林为研究对象,分析降雨特征对兴安落叶松林降雨再分配过程中K~+的影响。[方法]对林外降雨、穿透雨、灌木穿透雨、树干径流和枯透水进行了野外观测、取样和室内实验测定。[结果]结果表明:(1)研究期间兴安落叶松林林外降雨总量为266.0 mm,平均次降雨强度0.074 mm·min~(-1);降雨再分配过程中K~+含量平均值排序为枯透水树干径流灌木穿透雨穿透雨林外降雨,其中林外降雨中K~+含量在0.227 2.631 mg·L~(-1)之间,变化幅度较大,穿透雨中K~+含量波动在2.198 3.053 mg·L~(-1)之间,枯透水中K~+含量波动较小,稳定在3.077 3.281 mg·L~(-1)之间。(2)降雨量和降雨历时对降雨再分配过程中K~+含量均表现为正相关,随降雨量和降雨历时的增加K+含量的增加幅度呈上升趋势;而降雨强度和降雨间隔期对K~+含量增加幅度的影响则反之,但当降雨强度大于0.041 mm·min~(-1)时,K+含量的增加幅度开始出现转折,呈上升趋势;当降雨间隔期增大至233.28 h时,K~+含量的增加幅度趋于稳定。(3)影响林外降雨中K~+含量的主导因子是降雨间隔期,影响穿透雨、灌木穿透雨和树干径流中K~+含量的主导因子均为林外降雨量,而对枯透水中K~+含量起主导作用的则为降雨强度。[结论]降雨量、降雨历时、降雨强度以及降雨间隔期均会对降雨再分配过程中各个层次的K~+含量产生不同程度的影响。降雨再分配过程中K~+含量平均值大小排序为枯透水树干径流灌木穿透雨穿透雨林外降雨,其中大气降雨中K~+含量在5月和9月较高,穿透雨中K~+含量在5—10月呈波动式变化,灌木穿透雨中K~+含量变化幅度较大,而树干径流和枯透水中K~+含量较稳定。降雨量和降雨历时对降雨再分配过程中K~+含量的影响均表现为正相关。对林外降雨中K~+含量影响程度由大到小排序依次为降雨间隔期降雨强度降雨历时降雨量,穿透雨中K~+含量与各影响因素的灰关联度大小顺序依次为降雨量降雨历时降雨强度降雨间隔期,灌木穿透雨和树干径流中K~+含量与各影响因素的灰关联度排序和穿透雨一致,影响的主导因子均为降雨量,枯透水中K~+含量与各影响因素的灰关联度大小顺序依次为降雨强度降雨间隔期降雨历时降雨量。     

Partial characterization of stress-induced carboxylesterase from adults of <Emphasis Type="Italic">Stegobium paniceum</Emphasis> and <Emphasis Type="Italic">Lasioderma serricorne</Emphasis> (Coleoptera: Anobiidae) subjected to CO<Subscript>2</Subscript>-enriched atmosphere

The kinetics effects of carbon dioxide enriched atmosphere on carboxylesterase (CarE) activity from Stegobium paniceum and Lasioderma serricorne were comparatively investigated here. The results showed that L. serricorne had significantly greater specific activity of CarE than S. paniceum [0.399 vs. 0.358 mmol (min mg)⁻¹]. Moreover, CarE of L. serricorne expressed a higher affinity (i.e. lower K _m value) to the substrate α-naphthyl acetate than S. paniceum (0.1 vs. 0.8 mM). The in vitro kinetics of CarE showed that there were no significant effects of controlled atmosphere on the affinity of carboxylexterase to α-naphthyl acetate for both pests besides increased of V _max values. Such result draws attention to the higher tolerance of L. serricorne to CO₂-enriched atmosphere and the necessary care required for managing this species with such a control tactic. The information also suggests a potential effect of esterases in mitigating the toxic effect of controlled atmosphere in insect pest species.