植物大年结实研究概述

大年结实指一个指物种群在不同年份同时产生具有很大变化的种子产量,这种生殖特征普遍存在于多年生植物中,是植物有性生殖过程中的一个重要进化对策。植物种子产量的周期性变化和种群内不同个体结实的同步程度是植物大年结实的两个重要特征。本文对大年结实的有关假说以及各自依据和缺陷进行了分析,讨论了植物种群内不同个体生殖同步性的程度和时间尺度的延续和空间尺度的异质性。     

西藏野生芥菜型油菜构件种群相互关系及其与气候因素的灰色关联度分析

以生物构件理论为基础,运用灰色关联分析技术对西藏野生芥菜型油菜种群构件结构与环境因子的关系进行了研究。结果表明:1)每株角果数、每角果粒数和粒重是产量构成的重要指标,随着每株角果数、每角果粒数和粒重的增大,西藏野生芥菜型油菜的产量明显增加,它们之间的构件因子关联度较大;2)主茎系统是西藏野生芥菜型油菜植株的基础,其间的关联性显示了西藏野生芥菜型油菜植株构件组成的整合作用;3)一级分枝长度、一级分枝角果数、二级分枝数、一级分枝粗度之间有较大的关联度,但与一级分枝发生高度关联度相对较小;4)研究的7个环境因子与西藏野生芥菜型油菜种群的生长关系均较密切,且温度是影响西藏野生芥菜型油菜分布和生命活动相对重要的环境因子,而降水为次要因子。     

凝血酶调节蛋白基因防治血管内膜增生狭窄的实验研究

目的:观察凝血酶调节蛋白(Thrombomodulin,TM)基因转染兔髂动脉损伤模型后,对动脉血管内膜增生狭窄的防治作用。方法:用注射式加压转染的方式对兔动脉壁转染pcDNA3.1/hTM质粒,再制造动脉损伤-阻滞模型,于术后3天、7天、14天、28天用免疫组化的方法观察TM蛋白在各组血管腔内的表达,术后14天、28天用彩色多普勒观察活体吻合口内径和血流流速;再做病理切片Verhoeff染色,观察血管内膜增生的程度、部位,计算血管内膜面积、中膜面积和血管狭窄率。结果:术后3天、7天、14天、28天hTM质粒转染组中hTM表达一直保持在高水平,7天达到高峰,14天、28天虽有所下降但是表达强度仍然高于载体质粒转染组合空白对照组。在术后14天、28天彩色多普勒观察测量吻合口内径:hTM质粒转染组分别为1.93mm±0.34mm,1.89mm±0.28mm;载体质粒转染组为1.59mm±0.43mm,1.38mm±0.28mm;空白对照组1.46mm±0.25mm,1.44mm±0.32mm。在这两个时间点,hTM质粒转染组血管狭窄率为32±23%,37±14%;载体质粒转染组为58±21%,63±17%;空白对照组为58±19%,61±23%。结论:hTM基因在转染动脉壁后能减少动脉损伤-阻滞模型在后期的血管内膜增生,改善血管的狭窄状况。     

Isolation and characterization of 11 microsatellite loci in the mangrove crab, Ucides cordatus (Ocypodidae: Ucidinae)

Eleven polymorphic microsatellite loci were described for the mangrove crab, Ucides cordatus, an important fishery resource on the Brazilian coast. The number of alleles observed at each locus varied between eight and 23. Observed and expected mean heterozygosities were 0.791 and 0.893 respectively. Amplification of all loci was highly successful, under the same polymerase chain reaction conditions. With the exception of P2D3, all loci adhered to the assumptions of the Hardy-Weinberg equilibrium and did not present deviations reflecting linkage disequilibrium. Given this, these markers will be extremely useful in future management programmes for U. cordatus stocks.     

Morphological and functional aspects of volatile-producing glands in bees (Hymenoptera: Apidae)

Abstract In this paper we focus on the occurrence and morphological aspects of exocrine glands in several bee species. Morphology of head labial, mandibular, Dufour, and abdominal tegumentar glands was investigated under light microscopy, scanning electron microscopy and transmission electron microscopy. Most of such glands present cells with cytoplasm homogeneous and acidophilic, or contain small apparently empty vacuoles. The cytoplasm cells' ultrastructure showed a well developed smooth endoplasmic reticulum, many polymorphic mitochondria, rare Golgi, lipid droplets, myelin figures, and many basal and apical plasma membrane infoldings. All these results are discussed in the text.     

Phosphorus benefits of different legume crops to subsequent wheat grown in different soils of Western Australia

Certain legume crops, including white lupin (Lupinus albus L.), mobilise soil-bound phosphorus (P) through root exudates. The changes in the rhizosphere enhance P availability to these crops, and possibly to subsequent crops growing in the same soil. We conducted a pot experiment to compare phosphorus acquisition of three legume species with that of wheat, and to determine whether the legume crops influence growth and P uptake of a subsequent wheat crop. Field pea (Pisum sativum L.), faba bean (Vicia faba L.), white lupin (Lupinus albus L.) and wheat (Triticum aestivum L.) were grown in three different soils to which we added no or 20 mg P kg^–1 soil (P0, P20). Growth, P content and rhizosphere carboxylates varied significantly amongst crops, soils and P levels. Total P content of the plants was increased with applied phosphorus. Phosphorus content of faba bean was 3.9 and 8.8 mg/pot, at P0 and P20, respectively, which was about double that of all other species at the respective P levels. Field pea and white lupin had large amounts of rhizosphere carboxylates, whereas wheat and faba bean had negligible amounts in all three soils at both P levels. Wheat grew better after legumes than after wheat in all three soils. The effect of the previous plant species was greater when these previous species had received P fertiliser. All the legumes increased plant biomass of subsequent wheat significantly over the unplanted pots in all the soils. Faba bean was unparalleled in promoting subsequent wheat growth on all fertilised soils. This experiment clearly demonstrated a residual benefit of the legume crops on the growth of the subsequent wheat crop due to enhanced P uptake. Faba bean appeared to be a suitable P-mobilising legume crop plant for use in rotations with wheat.     

Assessment of the repellent effect of Lippia alba essential oil and major monoterpenes on the cattle tick Rhipicephalus microplus

The control of Rhipicephalus microplus (Ixodida: Ixodidae) is achieved using synthetic acaricides. However, resistant tick populations are widespread around the world. Plant essential oils can act as repellents, keeping ticks away from hosts and decreasing the selection pressure on synthetic acaricides. The aim of this study was to evaluate the in vitro repellent effect of Lippia alba essential oil on R. microplus larvae. Leaves from two L. alba genotypes maintained under the same agronomic and environmental conditions were collected. Essential oil was extracted by hydrodistillation and analysed by gas chromatography–mass spectrometry (GC‐MS). The major monoterpenes detected in the chemical analysis were commercially acquired and tested. For the repellency test, a glass rod was vertically fixed to measure active climbing of approximately 30 R. microplus larvae aged 14–21 days in response to essential oils and monoterpenes. Repellency was evaluated at 1 h, 3 h and 5 h after treatment. Variation in repellent action was detected between the genotypes. The major monoterpenes identified in the essential oils (limonene and carvone) showed low repellent effects in comparison with intact essential oils. Thus, the present results showed that L. alba essential oil contains bioactive compounds with great repellent activity against ticks that varies according to the plant genotype.     

Synergism of thymol,carvacrol and eugenol in larvae of the cattle tick,Rhipicephalus microplus,and brown dog tick,Rhipicephalus sanguineus

The effects of combinations of the monoterpenes thymol and carvacrol and the phenylpropanoid eugenol in larvae of Rhipicephalus microplus (Canestrini, 1888) (Acari: Ixodidae) and Rhipicephalus sanguineus sensu lato (s.l.) (Acari: Ixodidae) were assessed by the larval packet test. The CompuSyn program was used to make qualitative assessments of the effects (synergistic, additive and antagonistic) of the associations. The effects of all combinations tested against R. microplus larvae were synergistic, with combination indices (CIs) <0.70. When tested against R. sanguineus, eight of the mixtures showed a synergistic effect (CI < 0.70); only the carvacrol + thymol mixture at LC₅₀ presented a moderate synergistic effect, with CIs between 0.70–0.90. This study is the first to determine the effects of the interactions of these substances in the control of these two tick species. The combinations of carvacrol + thymol, carvacrol + eugenol and thymol + eugenol have synergistic effects in R. microplus and R. sanguineus s.l. larvae.     

安徽大别山木本植物幼树小枝薄壁组织组成特征初探

木本植物次生木质部轴向薄壁组织和射线薄壁组织在物质存储和转运等功能中起着重要的作用, 剖析次生木质部薄壁组织组成有助于深入探究其功能, 而小枝木质部薄壁组织组成特征还缺乏研究。该研究以天马国家级自然保护区内的18种木本植物幼树为研究对象, 测算了各物种小枝木质部薄壁组织的组成含量并检测了其谱系信号, 结合有关树干薄壁组织含量数据集, 初步探讨木本植物小枝木质部薄壁组织含量特征。研究结果表明: (1) 18种木本植物幼树小枝的薄壁组织总含量为9.96%-18.56%, 平均为14.80%; 其中射线薄壁组织含量为7.74%-15.45%, 高于轴向薄壁组织的含量(1.13%-7.49%); (2)小枝中薄壁组织总含量呈低于树干的趋势, 其中小枝射线薄壁组织含量低于树干, 而轴向薄壁组织含量高于树干, 这可能是由器官差异和生活史阶段差异造成的; (3)轴向薄壁组织的含量具有显著的谱系信号, 即物种亲缘关系越近其含量越相近。该研究初步验证了木本植物次生木质部薄壁组织的谱系信号, 同时暗示了器官和生活史阶段差异对薄壁组织含量具有重要影响。