Inhibition of protein tyrosine phosphatase 1B by lupeol and lupenone isolated from Sorbus commixta

Protein tyrosine phosphatase 1B (PTP1B) appears to be an attractive target for the development of new drugs for type 2 diabetes and obesity. In our preliminary test, a MeOH extract of the stem barks of Sorbus commixta Hedl. (Rosaceae) showed strong PTP1B inhibitory activity. Bioassay?guided fractionation of the MeOH extract resulted in the isolation of two lupane?type triterpenes, lupenone (1) and lupeol (2). Compounds 1 and 2 inhibited PTP1B with IC₅₀ values of 13.7 ± 2.1 and 5.6 ± 0.9 μM, respectively. Kinetic studies revealed that both the compounds 1 and 2 are non?competitive inhibitors of PTP1B that decrease V_max values with no effect on K_m values.     

Leaflet morphometric variation of service tree (Sorbus domestica L.) in the Balkan Peninsula

Abstract

In most European countries, the service tree (Sorbus domestica L.) is a rare and threatened species and its conservation has been recognised as a priority. The aim of this study was to asses its morphologic variation in the western and central part of the Balkan Peninsula and in southern Central Europe. Three populations were analysed: one in Serbia, one in Bosnia and Herzegovina and one in Slovenia. In each population 30 trees were selected, and from each tree 30 leaves were collected for morphometric analysis based on nine leaflet morphological traits. Univariate (ANOVA) and multivariate (MANOVA) analysis of variance were used to estimate the variation within- and between populations and a discriminant analysis was performed to examine the structure of the between-population differences. The values of particular morphological traits found in our study did not differ considerably from the values reported elsewhere. The results revealed significant within- and between population variation. Variation within populations was highly significant for all the scored leaf morphological traits, while variation between populations was significant for all the studied traits except for the leaflet length. The discrimination between the three populations was significant. High percentages of correctly classified samples demonstrate good discriminating employability of the analysed leaf morphological traits and indicate differentiation of the analysed populations.     

龙苍沟国家森林公园7种花楸属植物的叶解剖特征及其环境适应性

采用石蜡切片法对四川省龙苍沟国家森林公园内7种花楸属（Sorbus）植物的叶解剖特征进行研究,探究其结构特征与生境的相关性。结果显示：7种植物的叶片均为典型的背腹叶;叶片厚度介于108.16~208.21 μm,种间差异极显著（P<0.01）;上表皮厚度均大于下表皮厚度,且复叶物种的下表皮细胞均有乳突;栅栏组织由1~2层细胞构成,仅多对西康花楸（S. prattii var. aestivalis）的栅海比（栅栏组织与海绵组织的厚度比）为1.93,其余6种植物的栅海比均小于1;中脉维管束均呈心型,为典型的外韧型维管束,种间中脉突起度存在极显著差异（P<0.01）。各解剖结构中,上、下表皮可塑性最大,在生境中具有较强的潜在适应能力;中脉可塑性最小,整体结构较为稳定。栅栏组织、海绵组织和中脉组织是7种植物中种间差异最大的解剖结构。叶解剖结构与生境因子的相关性分析表明,栅栏组织厚度、栅海比和紧密度与年降水量、最暖季降水和海拔正相关（P<0.05）,与季节性温差负相关（P<0.05）;中脉直径和突起度与季节性温差呈正相关（P<0.01）,与年降水量、最暖季降水和海拔正相关负相关（P<0.05）。叶解剖结构性状的适应性变化,体现了7种花楸属植物在龙苍沟国家森林公园的生存策略。     

花楸属一新种——天堂花楸

本新种与黄山花楸(Sorbus amabilis Cheng ex Yü)近缘,区别在于前者羽状小叶6～7对,边缘圆钝锯齿,托叶宽披针形,花部雄蕊20枚,10长,10短,复伞房果序排列紧密,果多达160～195粒。     

Aphid galls accumulate high concentrations of amino acids: a support for the nutrition hypothesis for gall formation

The nutrition hypothesis for the adaptive significance of insect gall formation postulates that galls accumulate higher concentrations of nutritive compounds than uninfested plant tissue, resulting in a high performance of the gall former. This hypothesis has been supported by some taxa of gall insects, but not by taxa such as cynipid wasps. Aphid galls are expected to require higher levels of nitrogen than other insects’ galls with a single inhabitant, because aphid galls are required to sustain a number of aphids reproducing parthenogenetically over two generations. The present study tested this hypothesis by evaluating aphid performance and amino acid concentration in phloem sap, using the aphid Rhopalosiphum insertum (Walker) (Homoptera: Aphididae), which establishes colonies on leaves of Sorbus commixta Hedlund or in galls of the aphid Sorbaphis chaetosiphon Shaposhnikov (Homoptera: Aphididae). We prepared the gall and non‐gall treatments on trees of S. commixta, in which R. insertum fundatrices were reared and allowed to reproduce. In S. chaetosiphon galls, R. insertum colonies propagated more rapidly, and the second generation grew larger and more fecund than on ungalled leaves. The amount of amino acids exuding from cut galled leaves was fivefold that in ungalled leaves; however, there was no significant difference in the amino acid composition between galled and ungalled leaves. In the intact leaves, total amino acid concentration in the phloem sap declined rapidly from late April to late May; however, the galls retained this high amino acid concentration in developing leaves for 1 month. These results indicate that the improved performance in R. insertum is ascribed to the increased concentration of amino acids in galled leaves. We suggest that S. chaetosiphon galls function to promote the breakdown of leaf protein, leading to an increased performance of gall‐inhabiting aphids.     

Natural regeneration of trees in urban woodlands

Abstract. We studied tree regeneration, a key process for the existence of urban woodlands. We hypothesized that, besides the usual biological factors, anthropogenic ones (fragmentation, wear, pollution etc.) determine the regeneration success of tree species in urban woodlands. To test this hypothesis, within an observational setting, we collected data from 30 urban woodlands in the cities of Helsinki and Vantaa, Finland. We defined the number of living saplings (30–200 cm in height) as an indicator of regeneration success and used regression analysis to test different factors as independent variables. The results showed that different tree species responded differently to urban pressure. The regeneration of Picea abies decreased with increasing fragmentation of the forest landscape, whereas for the other most common (deciduous) species, regeneration increased. Wear, measured as total path area per study site, had a negative effect on regeneration success. An a posteriori examination of the data suggested that coarse woody debris might promote regeneration. We conclude that, although tree regeneration in general is not threatened in urban woodlands in the area we studied, the species composition may gradually change. We discuss some management implications for counteracting the urban pressures on tree regeneration.     

花楸腋芽增殖途径快繁技术研究

选用花楸茎节为外植体进行组培腋芽增殖途径研究,结果表明：利于花楸生长的最适宜基本培养基为MS培养基;芽诱导培养基为1/2MS+6-BA 2.5 mg·L^-1+2.4-D 0.5 mg·L^-1;增殖培养基为MS+6-BA（1.600~2.100）mg·L^-1+NAA（0.140~0.230） mg·L^-1,平均繁殖系数达到13倍以上;继代壮苗培养的最佳培养基为MS+6-BA 0.2 mg·L^-1+IBA 0.2 mg·L^-1;在1/2MS+IBA 0.3 mg·L^-1培养基上,平均生根数为5.96,生根率达90.20%。将生根后的组培苗移栽至腐殖土：泥炭土：河沙（比例为3：2：1）的基质中,成活率达95.55%。     

花楸(Sorbus pohuashanensis)导管分子穿孔板的类型及演化

对花楸茎次生木质部进行离析研究,发现其导管穿孔板有两种类型,即网状穿孔板和单穿孔板,并且还有5种过渡类型,具不同类型穿孔板的导管分子有3种类型,即两端均为网状穿孔板的导管分子;一端为网状穿孔板,另一端为单穿孔板的导管分子;两端的均为单穿孔板的导管分子,在花楸个体发育过程中穿孔板类型的演化重演了系统发育过程中导管网状穿孔板演化成单穿孔板的过程。