达乌里秦艽的传粉生物学研究

对达乌里秦艽3个自然居群和1个人工栽培居群进行了两年的传粉生态学研究.研究发现:(1)达乌里秦艽套袋花均不结实,说明雌雄异熟和雌雄异位这两种花部机制成功阻止了主动自交,且不存在无融合生殖现象.(2)隔离传粉昆虫导致花寿命明显延长,授粉会导致花冠提前闭合,说明达乌里秦艽的花寿命具有可塑性,可通过延长花寿命确保成功繁殖.(3)在一个自然居群中证明存在花粉限制,且该居群的花寿命显著长于另外两个没有花粉限制的自然居群.(4)在整个雌性持续期柱头都具有一定的可授性,且在第2天可授性最高,随后逐渐降低;开花后期柱头可授性降低,使植物维持花开放资源投入的产出将有可能降低.研究表明,达乌里秦艽在严重缺乏传粉者的情况下,延长花寿命仅能部分弥补传粉者的不足,该物种在部分居群中仍有可能存在花粉限制.     

Viability of the encysted metacercariae of Echinostoma caproni judged by light microscopy versus chemical excystation

The purpose of this study was to determine the viability of encysted metacercariae of Echinostoma caproni stored in Locke's solution 1:1 at 4 C for 1-24 wk. Viability was judged by light microscopy (LM) based on morphological characteristics of the encysted metacercariae versus chemical excystation of the cysts in a trypsin-bile salts excystation medium. The percent viability was very similar under both methods of assessment at 4, 8, and 16 wk poststorage. At 1 and 24 wk poststorage, viability was found to be about 2x greater based on excystation than using LM. We concluded that LM alone underestimated the viability of cysts and that determination of cyst viability was more accurate under assessment by chemical excystation.     

Coupling between neuronal firing rate, gamma LFP, and BOLD fMRI is related to interneuronal correlations

BACKGROUND: To what extent is activity of individual neurons coupled to the local field potential (LFP) and to blood-oxygenation-level dependent (BOLD) functional magnetic resonance imaging (fMRI)? This issue is of high significance for understanding brain function and for relating animal studies to fMRI, yet it is still under debate. RESULTS: Here we report data from simultaneous recordings of isolated unit activity and LFP by using multiple electrodes in the human auditory cortex. We found a wide range of coupling levels between the activity of individual neurons and gamma LFP. However, this large variability could be predominantly explained (r = 0.66) by the degree of firing-rate correlations between neighboring neurons. Importantly, this phenomenon occurred during both sensory stimulation and spontaneous activity. Concerning the coupling of neuronal activity to BOLD fMRI, we found that gamma LFP was well coupled to BOLD measured across different individuals (r = 0.62). By contrast, the coupling of single units to BOLD was highly variable and, again, tightly related to interneuronal-firing-rate correlations (r = 0.70). CONCLUSIONS: Our results offer a resolution to a central controversy regarding the coupling between neurons, LFP, and BOLD signals by demonstrating, for the first time, that the coupling of single units to the other measures is variable yet it is tightly related to the degree of interneuronal correlations in the human auditory cortex.     

新疆蓝刺头化学成分研究

以新疆蓝刺头(Echinops ritro L.)全草为研究材料,通过硅胶柱色谱,Sephadex LH-20柱色谱,重结晶等技术对新疆蓝刺头化学成分进行分离纯化,通过理化性质分析及1H-NMR,13C-NMR等技术对化合物结构进行鉴定.结果表明,共分离出5个化合物,分别是三萜类化合物蒲公英甾醇乙酰酯(化合物1)、蒲公英甾醇(化合物2)、黄酮苷类化合物金丝桃苷(化合物3)、胡萝卜苷(化合物4)与β-豆甾醇葡萄糖苷(化合物5).其中化合物1,2,5首次从该种植物中分离,化合物3为首次从该属植物中分离.     

HPLC法测定银州柴胡中五种皂苷的含量

首次建立HPLC法同时测定银州柴胡中柴胡皂苷a、c、d、e和f五种皂苷含量的方法。流动相为乙腈-水梯度洗脱,柱子为HibarRT RP-18(4.6 mm×250 mm,5μm),流速1.0 mL/min,柱温30℃,检测波长210 nm。柴胡皂苷a、c、d、e和f的线性范围及相关系数分别为:21.78～43.56μg(r=0.9993),3.94～9.85μg(r=0.9994),20.68～51.70μg(r=0.9998),1.67～5.57μg(r=0.9997),1.91～6.70μg(r=0.9992);柴胡皂苷a、d的加样回收率分别为101.5%和98.5%。该方法操作简便,结果准确,重现性好,为柴胡药材多指标质量分析方法的建立和银州柴胡药用提供了参考依据。     

反相高效液相色谱法测定升麻药材中升麻苷H-1的含量

建立升麻药材中升麻苷H-1含量测定的反相高效液相色谱分析方法。使用H&E XP ODS-A色谱柱(4.6 mm×250 mm5,μm),流动相为乙腈-水-磷酸(35∶65∶0.4),流速为1 mL/min,柱温为26℃,检测波长203nm。测得升麻苷H-1线性范围为0.95～28.5μg/mL(r=0.9999),平均回收率(n=6)为99.35%(RSD=2.79%),不同来源批次升麻药材含量测定结果表明,升麻药材中升麻苷H-1含量为0.53%～1.09%,综合分析批样品含量测定结果,建议升麻药材中含升麻苷H-1应不低于0.4%。本方法简便、准确、重复性好、专属性强,可作为升麻药材质量控制方法。     

6-Carboxyfluorescein and structurally similar molecules inhibit DNA binding and repair by O⁶-alkylguanine DNA alkyltransferase

Human O⁶-alkylguanine-DNA alkyltransferase (AGT) repairs mutagenic O⁶-alkylguanine and O⁴-alkylthymine adducts in single-stranded and duplex DNAs. These activities protect normal cells and tumor cells against drugs that alkylate DNA; drugs that inactivate AGT are under test as chemotherapeutic enhancers. In studies using 6-carboxyfluorescein (FAM)-labeled DNAs, AGT reduced the fluorescence intensity by ∼40% at binding saturation, whether the FAM was located at the 5′ or the 3′ end of the DNA. AGT protected residual fluorescence from quenching, indicating a solute-inaccessible binding site for FAM. Sedimentation equilibrium analyses showed that saturating AGT-stoichiometries were higher with FAM-labeled DNAs than with unlabeled DNAs, suggesting that the FAM provides a protein binding site that is not present in unlabeled DNAs. Additional fluorescence and sedimentation measurements showed that AGT forms a 1:1 complex with free FAM. Active site benzylation experiments and docking calculations support models in which the primary binding site is located in or near the active site of the enzyme. Electrophoretic analyses show that FAM inhibits DNA binding (IC₅₀ ∼ 76 μM) and repair of DNA containing an O⁶-methylguanine residue (IC₅₀ ∼ 63 μM). Similar results were obtained with other polycyclic aromatic compounds. These observations demonstrate the existence of a new class of non-covalent AGT-inhibitors. After optimization for binding-affinity, members of this class might be useful in cancer chemotherapy.     

GABA_A受体在酒精依赖中作用的研究进展

酒精依赖的产生机制是由特定的GABAA受体亚单位介导的,并且能够影响其它GABAA受体亚单位,使其对一定剂量的酒精敏感。此外酒精还可以通过细胞内信号转导途径影响GABA在大脑不同区域及核团单元的表达。焦虑、抗惊厥、镇静催眠、认知功能障碍等由酒精依赖产生的现象或者机制,均与GABA受体的介导有关。这些机制包括酒精对GABAA受体的直接或间接的作用,以及GABA的合成和释放。因此对GABAA受体功能的研究,将有助于人们关注酒精依赖现象及其治疗手段,为寻找酒精依赖治疗药物和治疗酒精中毒的机制的提供新线索。     

认知负荷对色词Stroop干扰效应的影响

目的:依据负荷理论,认知负荷会导致选择性注意任务中干扰刺激干扰效应的增加.本研究目的在于检验两种类型的认知负荷对色词Stroop干扰效应的影响.方法:实验一通过比较色词Stroop任务与言语工作记忆任务同时进行的双任务区组(高负荷条件)与单任务区组(低负荷条件)来检验认知负荷对构成Stroop干扰效应的语义冲突及反应冲突产生的影响.实验二则通过比较色词Stroop任务与言语工作记忆任务相协调的双任务区组(高负荷条件)与单任务区组(低负荷条件)来操纵认知负荷.结果:实验一的结果显示工作记忆负荷变化对语义冲突及反应冲突均不产生影响.实验二发现虽然在反应时指标上认知负荷与一致性之间未产生显著交互作用,但在错误率指标上两者交互作用达到显著,说明在高认知负荷条件下反应冲突显著增加了.结论:认知负荷对选择性注意任务中干扰刺激干扰效应的影响取决于认知负荷类型及冲突所发生的水平.