鸭粪提取物对水稻纹枯病菌的影响及其有效成分分析

为探明稻鸭共养模式抑制水稻纹枯病发生的原因,以稻鸭共养模式的鸭粪提取物为研究对象,对其抑菌活性及有效成分进行了测定和分析,以期为水稻纹枯病生物防治提供新的途径。结果表明:鸭粪乙醇提取物对水稻纹枯病菌有抑制作用,24h内最高菌丝生长抑制率和EC50分别为88.64%、26.11mg·mL-1;鸭粪乙醇提取物经萃取分离得到石油醚和乙酸乙酯两种组分,其中石油醚组分抑菌效果较弱,乙酸乙酯组分抑菌能力较强,其对水稻纹枯病菌抑制率为89.70%,EC50为15.52mg·mL-1;对乙酸乙酯组分进行硅胶柱层析分离得到5种流份,其中第2流份有显著抑菌活性,在24h和48h内对水稻纹枯病菌的抑制率分别为89.58%和80.36%。GC-MS分析表明,鸭粪的抑菌物质主要为酚酸类和含硫醇有机物质,进一步纯化和鉴定有待研究。     

Cytotoxicity of cycloartane triterpenoids from aerial part of Cimicifuga foetida

Our previous study had demonstrated cytotoxicity of EtOAc fraction from aerial part of Cimicifuga foetida on various cancer cell lines. In the present study, we investigated the cytotoxicity of five cycloartane triterpenoids isolated from the EtOAc fraction. Compounds (1,2,3) showed moderate cytotoxic activity on R-HepG2 cells and drug resistant sub line R-HepG2 but exhibited less toxicity against primary cultured normal mouse hepatocytes. Compounds (4) and (5) were inactive on all tested cell lines.     

Catechin transformation as influenced by aluminum

Polyphenols (catechins) are vital biomolecules in tea plants (Camellia sinensis), which are well-known as typical Al accumulators. However, the interaction between Al and catechin remains obscured. The objective of the present study was to investigate the effect of Al on the transformation of (+)-catechin. Solutions with OH/Al molar ratios of 2.5 (pH 5.5) and 3.0 (pH 7.0) prepared at Al/catechin molar ratios (R) of 0, 0.2, 0.4, 0.6, 0.8, and 1.0 were aged for 7 and 30 days, respectively. The precipitates were collected and examined by wet chemistry, X-ray diffraction, transmission electron microscopy, electron spin resonance (ESR), cross-polarization magic angle (CPMAS) 13C nuclear magnetic resonance (13C NMR) analyses, and Fourier transformation infrared absorption spectrometry (FT-IR). The weight of the precipitates increased with increasing Al/catechin molar ratios and with prolonged aging. The molar ratios of Al/catechin in the precipitates increased with increasing initial Al/catechin molar ratios and were close to the initial solution Al/catechin molar ratios. The chemical analysis and spectroscopic studies indicated that Al was bonded with catechin, forming a 1:1 type complex. The reaction of crystalline catechin with Al resulted in the formation of X-ray noncrystalline precipitates. The solid-state CPMAS 13C NMR spectra of the precipitates show the change in chemical shifts of catechin as a result of catechin complexation with Al. The FT-IR spectra of the Al-catechin precipitates also show the loss of absorption bands of several functional groups compared with catechin. The FT-IR data substantiate this reasoning. The ESR spectra of the precipitates show a single symmetrical line devoid of any fine splitting, indicating the presence of free radicals of semiquinones, which are commonly present in humified materials.     

FucP mediates fucose to regulate T3SS in Edwardsiella piscicida and promotes intestinal colonization in Tilapia

Aquaculture International - Edwardsiella piscicida (E. piscicida) is a common pathogen in freshwater and marine environments and an important intestinal pathogen of fish. Fucose large presence in...     

两种氟虫双酰胺复配制剂拌种对直播晚稻蓟马的控制效果及水稻生长的影响

为筛选直播晚稻蓟马的防治药剂,采用拌种法在大田试验了两种氟虫双酰胺复配制剂对直播水稻蓟马的控制效果,并考查了其对二化螟、稻纵卷叶螟的兼治效应及对水稻生长的影响。结果表明,48%氟虫双酰胺?噻虫啉SC 4~8 g a.i./kg种子处理拌种,可有效控制水稻苗期稻蓟马危害,药后14天杀虫和保叶效果分别为88.89%~95.03%和85.63%~91.67%,药后21天分别为87.64%~94.49%和78.86%~89.69%;2 g a.i./kg种子处理防效明显下降。同时,对二化螟具有兼治效果,并可刺激稻苗生长,提高水稻生长后期结实率和产量,而对稻纵卷叶螟防效较低。10%氟虫双酰胺?阿维菌素SC 1.5~3 g a.i./kg种子拌种对二化螟具有较好的控制效果,对稻蓟马和稻纵卷叶螟防效较低。因此,48%氟虫双酰胺?噻虫啉SC 4~8 g a.i./kg种子处理拌种可推荐用于水稻苗期稻蓟马和二化螟防治,而10%氟虫双酰胺?阿维菌素SC拌种处理不宜用于水稻苗期稻蓟马治理。     

三线闭壳龟、黄喉拟水龟、黄缘盒龟及其地方品系外部形态特征比较研究

本文首次对中国珍稀龟类三线闭壳龟（Cuora Trifasciata）、黄喉拟水龟(Mauremys mutica)、黄缘盒龟(Cistoclemmys flavomarginatas)及其地方品系的外部形态特征和差异进行了比较研究,为制定相应的龟类种质标准,保护和合理利用龟类资源提供技术资料。     

不同供氮水平下野慈菇营养元素（N）的生殖分配

通过不同氮水平稻田杂草野慈菇（Sagittatia trifolia）的取样测定,研究了野慈菇在开花前期、盛花期和结实期各构件的营养元素（N）生殖分配特点。结果表明：从开花前期到结实期,野慈菇各器官中的全氮含量及总氮含量基本呈增加趋势,根茎中氮元素分配比例上升,叶中氮元素分配比例下降,生殖器官中氮元素分配比例上升;在盛花期,氮元素分配格局表现为：叶>根茎>花>生殖附属器官（花葶）,随着供氮量的增加,根茎中氮元素分配呈增大趋势,叶中氮元素分配呈减小趋势,氮元素生殖分配比例为：N2>N3>N1>CK;在结实期分配格局,则为：根茎>叶>果>生殖附属器官（花葶）,优先将氮元素分配给营养贮藏器官--根茎,随着供氮量的增加,根茎中氮元素分配呈下降趋势,叶中氮元素分配呈上升趋势,氮元素生殖分配比例为：N3>N2>CK>N1;同时,在低供氮量下（CK和N1）,野慈菇以无性繁殖为主;在高供氮量下（N2和N3）,野慈菇则以有性繁殖为主。     

基于农户意愿的农村居民点宜居性调查研究——以重庆潼南县桂林街道八角村为例

农村居民点的宜居性将会影响居民点聚集效益的形成及农村集体建设用地的集约利用水平。笔者在对研究区实际调研的基础上,运用农户入户调查法、GIS技术,依据农户意愿对现存农村居民点进行宜居性调查研究。结果表明,宜居农村居民点应具有的条件包括：农户可接受的耕作半径、生产方便;道路通达度较高;满足农民下一代受教育的需求;完善的基础设施建设。     

广宁县竹子资源培育利用展望

对广宁县竹林资源及其分布进行了概述,探究了广宁县主要乡土竹种:青皮竹、茶秆竹的培育技术.分析了广宁县竹林资源的应用情况,试图阐明今后一段时间内广宁县竹林资源的研究方向和利用趋势.     

早竹覆盖栽培的衰老生理机制

研究不同覆盖时间不同年龄竹林的内源激紊、营养和C/N的变化,揭示早竹覆盖栽培衰老生理机制,丰富植物衰老理论和指导退化竹林更新复壮.结果表明:1)覆盖促进早竹衰老是从竹鞭衰老开始的,与竹叶关系不大.2)根部GA3/ABA、IAA/ABA、(GA3+IAA)/ABA激素比值调控竹子衰老,(GA3+IAA)/ABA降低到一定阚值时触动竹鞭的衰老,反之,比值高抑制衰老;且以GA3/ABA为主,IAA/ABA为辅;而不是一般植物根部CTK合成量减少和向地上部分运输减少所致,CTK不是主要的衰老抑制型激素,没有参与早竹激素衰老调控,显示早竹衰老激素调控机制的特殊性,这是由竹子的生物学特性所决定的.3)早竹衰老不是由于营养亏缺和C/N比值的升高所引发,C/N比值的升高是激素调控的结果,而不是导致竹子衰老的原因,竹子的衰老是由激素调控.