沙枣花蜜腺的发育解剖学研究

沙枣的花蜜腺位于花柱基部的筒状花盘上,属花盘蜜腺,其蜜腺位于花盘外方,由分履表皮和产蜜组织组成。分泌表皮具有角质层和变态的气孔器。产蜜组织在发育过程中,其液泡和淀粉粒都随着蜜腺的发育呈现一定的消长规律,最后形成的蜜汁由盘状蜜腺表面的气孔泌出。     

披针叶胡颓子中的一个新木脂素

从披针叶胡颓子（Elaeagnus lanceolata）的干燥枝叶中分离得到19个化合物,其中isoamericanol B（1）为一新化合物,经波谱学方法鉴定其结构为rel-（7′Z）-（7β,8α）-3-methoxy-4,9′-dihydroxy-3′,7-epox-y-8,4′-oxyneolign-7′-ene。     

山西翅果油树的适生区预测及其对气候变化的响应

研究濒危物种生境在气候变化下的响应对保护物种多样性和保持生态系统功能完整性具有重要意义.本文选取我国特有濒危植物翅果油树为研究对象,以该物种73个野外调查数据和35个环境因子为基础,应用最大熵模型对山西翅果油树当前的适生分布区进行预测;进而结合政府间气候变化专门委员会第五次评估报告发布的气候模式数据,探讨未来不同气候情景下山西翅果油树分布格局的变化趋势.结果表明:受试者工作特征曲线分析法的AUC值为0.987,表明模型的模拟精度很好且预测可靠性高;刀切法检验结果显示,降水量季节变化、温度年变化范围、年均温、等温线、表层土p H值和年降水量是影响翅果油树分布的主要环境因子,其累积贡献率达到了94.8%;当前,山西翅果油树的适生区主要集中在山西省吕梁山南部和中条山地带;未来不同气候情景下,到21世纪70年代翅果油树适生区面积均有不同幅度的缩减,低浓度情景(RCP 2.6)下呈先增后减趋势,中高浓度情景(RCP 4.5和RCP8.5)下响应较敏感且呈先减后增趋势.两个不同适生区的空间分布格局对气候变化也有不同的响应,吕梁山南部表现出纬度方向的轻微波动,而中条山地带则是海拔方向的迁移.     

白花地胆草单体EM-12诱导2774-C10细胞G_1/S期阻滞及细胞凋亡的分子机制研究

目的:研究白花地胆草(Elephantopus mollis H.B.K.)的乙醇提取物EM-12抗肿瘤作用分子机制。方法:MTT检测EM-12对卵巢癌细胞活性影响;克隆形成抑制实验检测EM-12对卵巢癌细胞增殖能力的影响;GO功能分析(gene ontology analysis)分析EM-12对卵巢癌2774-C10细胞的影响;PI单染检测细胞周期;Annexin V-FITC/PI双染法检测细胞凋亡;Western blotting检测细胞凋亡、周期相关蛋白。结果:MTT实验结果表明,EM-12可以显著抑制卵巢癌细胞的活性;RNASeq及GO功能分析表明EM-12诱导2774-C10发生G1/S期阻滞;克隆形成抑制实验结果表明,EM-12可以显著抑制卵巢癌细胞的增殖;流式细胞术结果表明,随着药物浓度的增加,凋亡率逐渐增加,并且G_1期细胞比例逐渐增加,S期细胞比例减少,发生G_1/S期阻滞。Western blotting结果表明,随着药物浓度的增加cyclin E_2、cyclin D_1、CDK2、CDK6蛋白水平下降,并伴随caspase-8、caspase-3活化及多聚ADP核糖聚合酶PARP酶切失活。结论:EM-12诱导卵巢癌细胞发生G_1/S期阻滞,且通过死亡受体通路诱导细胞凋亡。     

Distribution and N2-fixing activity of Frankia strains in relation to soil depth

The qualitative and quantitative distribution of Frankia strains infective on Elaeagnus angustifolia L. from different depths in the same soil (10–20 cm; 30–40 cm; 50–60 cm) were compared. The soil samples collected from a natural stand devoid of Elaeagnaceae were planted with Elaeagnus angustifolia L. seedlings. All plants became nodulated, demonstrating that Frankia strains were present at least down to 60 cm in the soil. The decreased density of Frankia strains was correlated to the decline of soil organic matter content with soil depth. DNA extracted from nodules produced on Elaeagnus angustifolia L. seedlings were polymerase chain reaction (PCR) characterized by amplifying the nif D-K intergenic spacer (IGS), using the polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) analysis. This showed the presence of seven nif-Hae III profiles within this Frankia community. Diversity of Frankia strains was maintained throughout the soil column, but the relative distribution of strains varied. Some nif-Hae III profiles were only found in the deeper soil, suggesting different selective advantages to withstand the constraints of soil depth. ¹⁵N₂ experiments indicated that all the strains tested had N₂-fixing activity. However, efficiency was not significantly different among nodules of different nif-Hae III profiles. Therefore, N₂-fixing activity does not seem to be the main factor responsible for the different distribution of Frankia strains at different soil depths.     

Ecophysiological differences among Leymus mollis populations across a subarctic dune system caused by environmental, not genetic, factors

Plant species that persist during succession, from the colonization to the stabilization stages, face major environmental changes. Such changes are believed to have significant effects on species performance. In subarctic coastal dune systems, Leymus mollis colonizes the embryo dunes, on the upper limit of the beach. It reaches its maximum density on the foredune, but also grows on older, stabilized ridges. This paper reports on the phenotypic variations of some ecophysiological traits associated with the persistence of L. mollis on a dune system on the east coast of Hudson Bay (northern Quebec). Leymus mollis ramets tend to have a lower net carbon assimilation rate and water use efficiency, and a higher substomatal CO₂ concentration on the stabilized dune than on the foredune. However, these physiological differences cannot be explained by differences in leaf morphology or nitrogen content. Under controlled conditions, ecophysiological differences observed in the field disappear, suggesting that these are not genetic but determined by environmental changes along the foredune-stabilized dune gradient. We propose that higher net carbon assimilation rate on the foredune might be related to higher sink strength in relation to the growth-stimulating effect of sand burial.     

EM-3通过Stat3通路诱导鼻咽癌细胞凋亡和G_2/M期阻滞并降低SP细胞比例

目的:研究白花地胆草(Elephantopus mollis H.B.K)的乙醇提取物EM-3抗肿瘤作用分子机制。方法:MTT、克隆形成抑制和细胞划痕实验检测EM-3对鼻咽癌细胞增殖、迁移能力的影响;Annexin V-FITC/PI双染法检测细胞凋亡;PI单染检测细胞周期;超速流式分选细胞仪检测鼻咽癌CNE2-S18肿瘤干细胞样SP细胞(side population cell)比例;Western blotting检测细胞凋亡、周期、侵袭迁移及肿瘤干细胞相关蛋白表达变化。结果:MTT、克隆形成抑制和细胞划痕实验结果表明,EM-3可以显著抑制鼻咽癌细胞的增殖,随着药物浓度的增大,细胞克隆数逐渐减少,体积逐渐变小,而且能够显著抑制鼻咽癌细胞的迁移;流式细胞术结果表明随着药物浓度的增加,凋亡率逐渐增加,并且G_2/M期细胞比例逐渐增加;超速流式分选细胞仪结果表明,EM-3可以显著降低CNE2-S18肿瘤干细胞样SP细胞的比例;Western blotting结果表明,随着药物浓度的增加,x IAP、Bcl-2、Cyclin D1、MMP2(药物高浓度)、MMP9、p-Met、Oct4(药物高浓度)及Sox2蛋白表达减少,而Cyclin B1、Bax蛋白表达增多,并伴随Caspase-9、Caspase-3活化及多聚ADP核糖聚合酶PARP酶切失活。结论:EM-3通过抑制Stat3通路诱导鼻咽癌细胞发生凋亡,并诱导G_2/M期阻滞。此外,EM-3经MMPs途径抑制鼻咽癌细胞迁移,同时可以有效降低CNE2-S18肿瘤干细胞样SP细胞干性。     

Autumnal changes in tissue nitrogen of autumn olive,black alder and eastern cottonwood

Two experiments were conducted to determine patterns of N change in tissues of autumn olive (Elaeagnus umbellata Thunb.) and black alder (Alnus glutinosa [L.] Gaertn.) during autumn in central Illinois, U.S.A. In the first study leaf nitrogen concentrations of autumn olive decreased 40% at an infertile minespoil site and 39% at a fertile prairie site throughout autumn whereas nitrogen concentrations in respective bark samples increased by 39% and 37%. Salt-extractable protein concentrations increased in bark and decreased in leaves over the sampling period. Free amino acid concentrations of autumn olive leaves decreased over the course of the experiment from peak concentrations in August. Asparagine, glutamic acid and proline were major constituents of the free amino acid pools in leaves. Total phosphorus concentrations of autumn olive leaves declined by 40–46% during autumn while bark concentrations of P did not significantly change.In the second experiment non-nodulated seedlings of alder receiving a low level of N-fertilization did not exhibit net resorption of leaf N during autumn whereas foliar N concentration of contrasting nonactinorhizal cottonwood plants (Populus deltoides Bartr. ex. Marsh) under the same fertilization regime decreased by 27% after the first frost. A gradual but significant decrease of 38% in foliar N concentration of nodulated alder seedlings grown under a low N-fertilization regime was associated with the cessation of nitrogenase activity during autumn in nodules. Compared with the low N fertilization regime, the higher level of N-fertilization resulted in smaller autumnal decreases of foliar N concentration in nodulated alder (17%) and in cottonwood (20%); but there was no decrease in foliar N concentration in non-nodulated alder. The higher level of N-fertilization promoted a greater accumulation of N in the roots than in the bark of both tree species after the first frost.Our results suggest that black alder lackingFrankia symbionts does not exhibit net leaf N resorption and that autumnal decreases in leaf N ofFrankia-nodulated black alder result primarily from declining foliar N import relative to export due to low temperature inhibition of N₂ fixation. In contrast, autumn olive exhibited greater and more precipitous autumnal declines in foliar N concentration than those of alder, and the pattern of N decline was unaffected by site fertility.     

Isolation and characterization of Frankia from nodules of actinorhizal plants of Pakistan

Frankia strains have been isolated from actinorhizal nodules of Alnus (2 strains), Casuarina (5 strains), Coriaria (1 strain), Datisca (3 strains), Elaeagnus (1 strain) and Hippophae (1 strain). The isolates were characterized for their growth on various carbon and nitrogen sources, nitrogen-fining ability in culture and nodulation of seedlings of the original host plant.     

The acetylene reduction assay inactivates root nodule uptake hydrogenase in some actinorhizal plants

Actinorhizal nodules do not usually evolve H₂ due to the action of an uptake hydrogenase. We have found that nodules of several Frankia symbioses evolved large amounts of H₂ gas when returned to air following exposure to 10 kPa C₂HT₂ during an acetylene reduction assay. Increased H₂ evolution in air persisted for several days when intact root systems of Alnus incana (L.) Moench (inoculated with Frankia UGL 011101) were treated with 10 kPa C.H₂ for 1 h. Full recovery of uptake hydrogenase activity required 4 to 8 days. Studies with crude homogenates of nodules of the same plants showed that hydrogenase (measured amperometrically with phenazine metho-sulfate as electron acceptor) was directly affected, since activity in treated nodules was only 10% of that in untreated nodules. A survey of actinorhizal symbioses revealed variation in the effect of an acetylene reduction assay on hydrogen metabolism. Nodules of three species, including Alnus rubra Bong, inoculated with Frankia HFPArD. showed complete inactivation of hydrogenase. H₂ evolution in air was 25% of the C₂H₂ reduction rate and H, evolution in Ar/O₂ was equal to the QH₂ reduction rate. Two symbioses, Ceanothus americanus L. (soil inoculant) and Batista glomerata Baill. (soil inoculant) showed no change following an acetylene reduction assay. A third group of symbioses showed an intermediate response.