Alkaloids and other constituents from Tribulus terrestris

Three new compounds, terrestribisamide, 25R-spirost-4-en-3,12-dione and tribulusterine, together with 10 known compounds, N-p-coumaroyltyramine, terrestriamide, hecogenin, aurantiamide acetate, xanthosine, fatty acid ester, ferulic acid, vanillin, p-hydroxybenzoic acid and β-sitosterol, were isolated and characterized from dried fruits of Tribulus terrestris. Structures of these compounds were determined by spectral analysis.     

八种新烟碱类杀虫剂对地熊蜂工蜂的毒性及风险评估

【目的】评价新烟碱类杀虫剂对地熊蜂Bombus terrestris工蜂的毒性和生态风险性,为温室施用新烟碱类杀虫剂提供科学依据。【方法】分别采用饲喂法和接触法测定了噻虫嗪、噻虫胺、啶虫脒、吡虫啉、烯啶虫胺、呋虫胺、噻虫啉和氟吡呋喃酮8种新烟碱类杀虫剂对地熊蜂成年工蜂的急性经口和急性接触毒性。同时评估了8种新烟碱类杀虫剂对地熊蜂工蜂的生态风险性。【结果】8种杀虫剂经饲喂法测定,噻虫胺对地熊蜂成年工蜂的毒性最高,24 h和48 h的LD 50值分别为0.0433和0.0330μg a.i./蜂;氟吡呋喃酮毒性最低,24 h和48 h的LD 50值分别为72.4119和67.9079μg a.i./蜂。接触法测定的毒性与饲喂法测得的结果一致,噻虫胺的毒性最高,24 h和48 h的LD 50值分别为0.0220和0.0192μg a.i./蜂;氟吡呋喃酮的毒性最低,24 h和48 h的LD 50值分别为141.7641和130.3062μg a.i./蜂。生态风险评估表明,啶虫脒、噻虫啉和氟吡呋喃酮对地熊蜂成年工蜂的经口毒性和接触毒性均表现为低风险,吡虫啉、烯啶虫胺和呋虫胺的毒性表现为中等风险。噻虫嗪和噻虫胺对地熊蜂成年工蜂的经口毒性表现为中等风险,而接触毒性则表现为高风险。【结论】检测的8种新烟碱类杀虫剂中啶虫脒、噻虫啉与氟吡呋喃酮对地熊蜂成年工蜂的毒性为低毒,而噻虫嗪、噻虫胺、吡虫啉、烯啶虫胺、呋虫胺这5种杀虫剂均为高毒。在设施蔬菜花期使用地熊蜂授粉时,建议禁用这5种中、高风险的新烟碱类杀虫剂,以避免对熊蜂授粉的危害,而另3种低风险药剂可根据田间试验情况合理施用。     

Litter effects on seedling establishment interact with seed position and earthworm activity

Seedling establishment is influenced by litter cover and by seed predators, but little is known about interactions between these two factors. We tested their effects on emergence of five typical grassland species in a microcosm experiment. We manipulated the amounts of grass litter, seed sowing position and earthworm activity to determine whether: (i) the protective effect of litter against seed predation depends on cover amount and seed sowing position, i.e., on top or beneath litter; (ii) seed transport by earthworms changes the effect of seed sowing position on seedling emergence; and (iii) seeds transported into deeper soil layers by earthworms are still germinable. Litter cover and presence of earthworms lowered seedling emergence. The impact of seed position increased with seed size. Emergence of large-seeded species was reduced when sown on the surface. Additionally, we found an important seed position × earthworm interaction related to seed size. Emergence of large-seeded species sown on top of the litter was up to three times higher when earthworms were present than without earthworms. Earthworms also significantly altered the depth distribution of seeds in the soil and across treatments: on average 6% of seeds germinated after burial. In contrast to the seed position effect, we found no size effect on mobility and germinability of seeds after burial in the soil. Nevertheless, the fate of different-sized seeds may differ. While burial will remove large seeds from the regeneration pool, it may enhance seed bank build up in small-seeded species. Consequently, changes in the amount of litter cover and the invertebrate community play a significant role in plant community composition.     

补充蒺藜提取物对男子拳击运动员肩、肘关节爆发力和耐力的影响

目的:研究补充蒺藜提取物对力量训练和耐力训练的男子拳击运动员肩、肘关节的爆发力和耐力的影响。方法:15名青少年男子拳击运动员随机分为训练对照组(n=7)和训练+蒺藜组(n=8,完成所有测试项目的n=6)。两组运动员同时进行3周大强度力量训练,休息4周,再进行3周中强度耐力训练,每周训练6d。训练+蒺藜组运动员每日上午训练前服用1250mg的蒺藜提取物胶囊,而对照组服用安慰剂。训练前、力量训练和耐力训练后,用瑞士CONTREX等速肌力测试仪检测两组运动员肩关节的屈伸肌、收展肌和肘关节的屈伸肌在90°/s和120°/s角速度运动时的相对峰力矩(峰力矩/体重)、相对平均功率(平均功率/体重)、相对总功(总功/体重)、做功疲劳度和屈伸肌(和收展肌)峰力矩比。结果:与训练前比较,力量训练和耐力训练可降低男拳击运动员肩和肘关节屈伸肌的相对总功(90°/s和120°/s),增加肩关节屈肌做功疲劳度(120°/s)(P均<0.05);与对照组比较,补充蒺藜提取物可改善男拳击运动员力量训练所致肩关节屈伸肌相对总功的减少及屈肌做功疲劳度的增加,以及耐力训练所致肘关节屈伸肌相对总功的降低(P均<0.05);其余各检测指标无显著差异。结论:补充蒺藜提取物可改善力量训练所致肩关节、耐力训练所致肘关节的屈伸肌爆发力和耐力的降低;但不影响肩关节收展肌的爆发力和耐力,也不影响肩和肘关节的稳定性。     

Density-related changes in selection pattern for major histocompatibility complex genes in fluctuating populations of voles

Host-pathogen interactions are of particular interest in studies of the interplay between population dynamics and natural selection. The major histocompatibility complex (MHC) genes of demographically fluctuating species are highly suitable markers for such studies, because they are involved in initiating the immune response against pathogens and display a high level of adaptive genetic variation. We investigated whether two MHC class II genes (DQA1, DRB) were subjected to contemporary selection during increases in the density of fossorial water vole (Arvicola terrestris) populations, by comparing the neutral genetic structure of seven populations with that estimated from MHC genes. Tests for heterozygosity excess indicated that DQA1 was subject to intense balancing selection. No such selection operated on neutral markers. This pattern of selection became more marked with increasing abundance. In the low-abundance phase, when populations were geographically isolated, both overall differentiation and isolation-by-distance were more marked for MHC genes than for neutral markers. Model-based simulations identified DQA1 as an outlier (i.e. under selection) in a single population, suggesting the action of local selection in fragmented populations. The differences between MHC and neutral markers gradually disappeared with increasing effective migration between sites. In the high-abundance year, DQA1 displayed significantly lower levels of overall differentiation than the neutral markers. This gene therefore displayed stronger homogenization than observed under drift and migration alone. The observed signs of selection were much weaker for DRB. Spatial and temporal fluctuations in parasite pressure and locus-specific selection are probably the most plausible mechanisms underlying the observed changes in selection pattern during the demographic cycle.     

Development and characterization of novel microsatellite markers for the common earthworm (Lumbricus terrestris L.)

We developed and characterized 10 highly polymorphic microsatellite loci from an SSR‐enriched genomic DNA library of the common earthworm (Lumbricus terrestris L). Characterization of these loci using 32 individuals revealed high levels of genetic diversity, five to 18 alleles per locus and a high observed and expected heterozygosity. These loci will be used for paternity analysis and population genetic studies of the co‐evolution between L. terrestris and its parasites.