Environmental controls on the carbon isotope composition of ecosystem-respired CO2 in contrasting forest ecosystems in Canada and the USA

We compared the carbon isotope composition of ecosystem-respired CO2 (delta13C(R)) from 11 forest ecosystems in Canada and the USA and examined differences among forest delta13C(R) responses to seasonal variations in environmental conditions from May to October 2004. Our experimental approach was based on the assumption that variation in delta13C(R) is a good proxy for short-term changes in photosynthetic discrimination and associated shifts in the integrated ecosystem-level intercellular to ambient CO2 ratio (c(i)/c(a)). We compared delta13C(R) responses for three functional groups: deciduous, boreal and coastal forests. The delta13C(R) values were well predicted for each group and the highest R2 values determined for the coastal, deciduous and boreal groups were 0.81, 0.80 and 0.56, respectively. Consistent with previous studies, the highest correlations between delta13C(R) and changes in environmental conditions were achieved when the environmental variables were averaged for 2, 3 or 4 days before delta13C(R) sample collection. The relationships between delta13C(R) and environmental conditions were consistent with leaf-level responses, and were most apparent within functional groups, providing support for our approach. However, there were differences among groups in the strength or significance, or both, of the relationships between delta13C(R) and some environmental factors. For example, vapor pressure deficit (VPD) and soil temperature were significant determinants of variation in delta13C(R) in the boreal group, whereas photosynthetic photon flux (PPF) was not; however, in the coastal group, variation in delta13C(R) was strongly correlated with changes in PPF, and there was no significant relationship with VPD. At a single site, comparisons between our delta13C(R) measurements in 2004 and published values suggested the potential application of delta13C(R) measurements to assess year-to-year variation in ecosystem physiological responses to changing environmental conditions, but showed that, in such an analysis, all environmental factors influencing carbon isotope discrimination during photosynthetic gas exchange must be considered.     

The nematicidal and proteomic effects of Huanong AVM (analog of avermectin) on the pine-wilt nematode, Bursaphelenchus xylophilus

Huanong AVM is a novel nematicide, which was synthesized from avermectin by selective oxidization of the hydroxyl group at C-4, followed by the reaction with glacial acetic acid. Effects of Huanong AVM on Bursaphelechus xylophilus are reported in this paper. Huanong AVM had strong nematicidal activity against B. xylophilus, with LC₅₀ values of 14.84 μg/mL, 12.49 μg/mL and 11.05 μg/mL, respectively, at 48 h, 72 h and 96 h after treatment. The proteins that responded to Huanong AVM were identified by proteomic analysis. 2-DE analysis revealed eighteen differentially accumulated protein spots. Five spots were successfully identified by MS analysis, and three Huanong AVM induced proteins were annotated in the database as LEVamisole resistant family member (lev-11), ACTin family member (act-4) and Hypothetical protein Y52B11A.10. Two Huanong AVM-up-regulated proteins were assigned as PIP Kinase family member (ppk-3) and Hypothetical protein B0432.6. These proteins are involved in signal transduction, maintaining cytoskeletal structure and LEVamisole resistance. These results point to pathways that are important for the mode of the action of Huanong AVM on B. xylophilus.     

FRP-钢复合管混凝土轴压短柱试验及应用研究

进行4个不同纤维类型和层数的圆形FRP-钢复合管混凝土短柱和1个对比短柱的轴压试验研究。试验研究结果表明：FRP-钢复合管混凝土的破坏过程基本都从试件中部开始发生FRP断裂，FRP逐渐丧失对钢管的约束力，在FRP断裂后构件保持一定的残余承载力，随着FRP的层数增加，极限荷载随之增加，在相同FRP层数的情况下，CFRP-钢复合管试件和BFRP-钢复合管试件对比，CFRP-钢复合管试件的混凝土峰值荷载较大，后者的延性提高效果明显，同时介绍FRP-钢复合管混凝土桥墩在试点工程中的应用情况。     

生态修复城市水系统研究进展

城市水系在维持城市的生态环境中占重要地位。由于经济利益的驱动,人们赖以生存的水环境发生了恶化。随着人们生态意识的觉醒,针对城市水系主要组成部分城市河道和景观水体的治理,产生了许多修复方法。     

竹节参引种驯化基地伴生植物调查研究

通过对竹节参引种栽培周围生长的植物种类进行调查,以探究那些伴生植物对引种驯化竹节参有利。结果表明,竹节参伴生植物共有27种,分属17科,主要是喜阴暗湿润的植物。其中主要伴生植物有苔藓类、黄鹌菜和弯曲碎米荠;偶见植物有鼠曲、茅梅、杠板归、龙葵、猪殃殃等。调查结果为竹节参引种驯化提供参考资料和有价值的建议。     

密花核果木抗肿瘤有效部位的筛选研究

采用3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐(MTT)法,以2种人肿瘤细胞株(SGC-7901、SPCA-1)为研究对象,对海南地区核果木属植物密花核果木的抗肿瘤有效部位进行筛选研究。采用硅胶柱色谱分离技术对石油醚、氯仿萃取部位进行进一步的分离,获得不同极性组分。抗肿瘤活性试验结果表明,石油醚、氯仿萃取部位及其不同极性组分显示不同程度的肿瘤细胞增殖抑制活性,是其抗肿瘤有效部位。     

宽叶十万错抗氧化性测定

采用分光光度法,并以抗坏血酸为阳性对照,考察宽叶十万错浸膏的多酚含量及其对1,1-二苯基-2-三硝基苯肼(DPPH)自由基、2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵(ABTS)自由基及羟自由基的清除活性。结果表明:宽叶十万错浸膏的多酚含量为197μg·mg-1,对DPPH自由基、ABTS自由基及羟自由基均具有一定的清除活性。结果表明,宽叶十万错具有一定的抗氧化活性,对人体具有良好的营养保健功效。     

无损检测在日本落叶松材性育种中的应用前景探讨

使用 Pilodyn和微秒计对20个日本落叶松无性系进行无损检测,研究无性系间无损检测指标的表型和遗传变异,结果表明：应力波速( SWV)的表型变异系数和遗传变异系数分别为5.09%和3.57%,低于 Pilodyn南向测定值(Ps)和北向测定值(Pn);3个无损检测指标无性系重复力的分布范围为0.34～0.48,说明它们受中等强度的遗传控制。研究无损检测指标与各材质性状间的关系,结果表明： Ps和 Pn与生长轮密度、早材密度、生长轮壁腔比和早材壁腔比呈极显著负相关; SWV与生长轮微纤丝角、早材微纤丝角和晚材微纤丝角呈极显著负相关,但与生长轮弹性模量、早材弹性模量和晚材弹性模量呈极显著正相关。多元回归分析表明,对 Ps,Pn和 SWV 贡献率排名前2位的材质性状分别为生长轮密度和早材壁腔比、生长轮密度和生长轮壁腔比以及早材微纤丝角和生长轮弹性模量。建立无损检测指标与相对应材质性状的线性回归方程,发现 Ps与生长轮密度间方程的决定系数(0.340)略小于 Pn与生长轮密度的决定系数(0.360); SWV 与早材微纤丝角、生长轮弹性模量间方程的决定系数分别为0.348和0.316。     

余甘子各器官多糖含量分析

研究通过分析比较了余甘子各器官之间、同品种不同植株之间、不同余甘子品种之间以及与野生资源之间的多糖含量。结果表明,余甘子各器官皆含有多糖类化合物,且差异均极显著,大小顺序为:鲜果肉(4.382%)>枝(4.169%)>干果肉(3.530%)>芽(2.951%)>根(2.162%)>老叶(1.750%)>幼叶(1.410%)>种子(0.965%)。不同品种余甘子同一器官的多糖含量也存在极显著差异。野生余甘与粉甘间鲜果肉和种子的多糖含量表现出极显著差异,其中2个野生植株(A、C)鲜果肉多糖含量高于粉甘,5个野生植株种子多糖含量均高于粉甘,3个野生植株(B、D、E)枝多糖含量高于粉甘。     

鸡第四脑室底壁和侧壁扫描电镜结构观察

本实验用扫描电镜对8只产蛋高峰期母鸡第四脑室底壁和侧壁进行了观察,结果表明,鸡第四脑室布满草丛状纤毛和毡样微缄毛,纤毛的分布在不同区域有一定差别.室底壁正中沟纤毛最为稀疏,在其两侧各有一条纤毛密集带,由密集带向外,纤毛密度逐渐减小;侧壁纤毛较底壁稀疏,侧壁后部的纤毛比前部更密.室管膜细胞可分为多纤毛细胞和少纤毛细胞,前者主要分布于底壁的两侧和侧壁的中后部,后者主要分布于底壁的正中沟和侧壁的前部.鸡第四脑室中存在着神经元样细胞、神经胶质样细胞和类组织细胞,各类细胞见于该脑室的各部,还发现有独立的神经纤维穿行于第四脑室壁的表面.