墨红鲜花香气(头香)成分分析

利用 XAD-4憎水性吸附树脂采集墨红头香,以毛细管气相色谱双柱保留指数和 GC/MS/DS 联用方法鉴定头香的化学成份。共分离鉴定或初步鉴定了45种组份,其中含量较大的有乙酸芳樟酯(14.98%),柠檬烯(12.07%),甲基苯甲醚(9.88%),香茅醇(4.82%),乙酸巳酯(3.98%),β-石竹烯(4.55%),芳樟醇(3.18%),正巳醇(3.17%)等.     

松嫩平原羊草、虎尾草群落钙元素时空分布的比较研究

本文分析了松嫩平原羊草（Ｌｅｙｍｕｓｃｈｉｎｅｎｓｉｓ）群落和虎尾草（Ｃｈｌｏｒｉｓｖｉｒｇａｔａ）群落钙元素在土壤中和植物体中的分布特征及季节动态,以及土壤中钠钙含量的关系。结果表明,两种群落的土壤水溶性和交换性钙含量均为春秋两季较高,夏季较低,优势种植物体中钙的含量为羊草明显高于虎尾草,根部均高于其它部位。两种群落土壤中交换性钙的垂直分布均以表层最低,并随着土层深度而逐渐增加,其中羊草群落各土层的含量均高于虎尾草群落。     

红豆杉组织培养中褐变问题的研究

本研究针对红豆杉组织培养中经常遇到的褐变问题,采取多种方法进行试验,力求最大限度地避免或减轻褐变。结果表明,选择合适的外植体、培养基和培养条件是至关重要的,此外,抗氧化剂、金属离子螫合剂、热激处理和活性碳处理等方法可在一定程度上减轻褐变的程度。综合考虑各种因素,经过筛选可以获得生长良好的不发生褐变的组织。     

空气CO2增高条件下荔枝叶片光合作用和超氧自由基产率

研究结果表明,生长在77±5PaCO₂分压下30d的荔枝幼树,其光合速率较大气CO₂分压(39.3Pa)下的低23%,光下线粒体呼吸速率和不包含光下呼吸的CO₂补偿点亦略有降低.空气CO₂增高使叶片最大羧化速率(V_cmax)和最大电子传递速率(J_max)降低,表明大气增高CO₂分压下叶片的光系统I(PSI)能量水平较低,叶片超氧自由基产率亦降低39%,叶片感染荔枝霜疫霉病率则从生长在大气CO₂分压下的1.8%增至9.5%.可能较低光合和呼吸代谢诱致较低的超氧自由基产率,而使叶片易受病害侵染.叶片受病害侵染后表现为超氧自由基的激增.在全球大气CO₂分压增高趋势下须加强对荔枝霜疫霉病的控制.     

内蒙古锡林河流域不同植物群落中羊草和糙隐子草水分利用效率的变异

用稳定性同位素技术,研究了锡林河流域不同群落和生境下羊草(Leymus chinensis ( Trin.) Tzvel.)和糙隐子草(Cleistogenes squarrosa (Trin.) Keng.)叶片δ13C值及其水分利用效率的变化.结果表明,在不同生境下,羊草和糙隐子草叶片δ13C 值随土壤水分含量的降低而增大,并与不同土层土壤水分含量均表现出极显著的线性负相关关系;而二者的叶片水分含量与土壤水分含量无显著的相关关系.这一结果说明,羊草和糙隐子草的水分利用效率均随土壤水分含量的降低而提高,而叶片水分含量保持相对稳定.这两种植物可能通过调节气孔导度、提高水分利用效率和增强渗透调节能力等生理生态机制适应水分状况不同的生境,从而使它们能够在锡林河流域不同植物群落中广泛分布并成为建群种或优势种.     

中华猕猴桃和美味猕猴桃的倍性变异及地理分布研究

根据已有的猕猴桃自然地理分布资料,通过对中华猕猴桃（Actinidia chinensis）和美味猕猴桃（A．deliciosa）野外分布居群的详细调查,利用流式细胞技术对我国西部高原台地向中东部丘陵平原过渡地带6个纯中华猕猴桃、1个纯美味猕猴桃和5个中华／美味猕猴桃同域分布居群共276个个体的倍性进行了检测。结果表明：（1）中华猕猴桃存在二倍体和四倍体,美味猕猴桃存在四倍体、五倍体和六倍体;（2）中华猕猴桃和美昧猕猴桃在经度和纬度的分布上存在显著差异（P〈0．05）,中华猕猴桃在经度上偏东分布而美味猕猴桃偏西,纬度分布上中华猕猴桃偏南而美味猕猴桃偏北;而且不同倍性小种在经、纬度分布上呈现显著差异（P〈0．05）,二倍体、四倍体、六倍体的分布在经度上依次从东到西、纬度上从南到北;（3）中华猕猴桃和美味猕猴桃不同倍性小种的海拔分布存在显著性差异（P〈0．05）,二倍体小种分布海拔最低,四倍体小种次之,六倍体小种海拔分布最高,但通过LSD分析四倍体个体和六倍体个体在海拔分布上不存在显著差异（P〉0．05）。通过对中华／美味猕猴桃这两种具有重要经济价值的果树的倍性变异及地理分布的探讨,提出了猕猴桃倍性小种分布的上述规律并给猕猴桃种质资源收集、评价、创新和可持续利用方面提供了初步的研究基础,尤其是为我国猕猴桃新品种选育提供了基础数据和科学依据。     

Analysis of novel angiotensin-I-converting enzyme inhibitory peptides from protease-hydrolyzed marine shrimp Acetes chinensis.

Acetes chinensis is an underutilized shrimp species thriving in the Bo Hai Gulf of China. In a previous study, we had used the protease from Bacillus sp. SM98011 to digest this kind of shrimp and found that the oligopeptide-enriched hydrolysate possessed antioxidant activity and high angiotensin I-converting enzyme (ACE) inhibitory activity with an IC50 value of 0.97 mg/ml. In this paper, by ultrafiltration, gel permeation chromatography and reversed-phase high-performance liquid chromatography (RP-HPLC), five peptides with high ACE inhibitory activity were purified from the shrimp hydrolysates and their sequences were identified by amino acid composition analysis and molecular weight (MW) analysis. Three of them, FCVLRP (a), IFVPAF (f) and KPPETV (j), were novel ACE inhibitory peptides. Their IC50 values were 12.3 microM, 3.4 microM and 24.1 microM, respectively, and their recoveries were 30 mg/100 g (solid basis of shrimp), 19 mg/100 g and 33 mg/100 g, respectively. Lineweaver-Burk plots for the three novel peptides showed that they are all competitive inhibitors. To test the ACE inhibitory activity of peptide a, f, j after they were digested by digestive enzymes in vivo, 12 derived peptides from FCVLRP and IFVPAF were synthesized based on their amino acid sequences and the cleavage sites of digestive enzymes. No digestive enzyme cleavage site was found in KPPETV. The IC50 values of the derived peptides were determined and the result showed that except for VPAF, FC and FCVL, the ACE inhibitory activity of the other nine derived peptides did not significantly change when compared with their original peptides. Surprisingly, five peptides had lower IC50 values than their original peptides, particularly for RP (IC50 value = 0.39 microM), which is about 30 times lower than its original peptide and almost the lowest IC50 value for ACE inhibitory peptides reported. Therefore, the novel peptides identified from A. chinensis hydrolysates probably still maintain a high ACE inhibitory activity even if they are digested in vivo. This is the first report about novel ACE inhibitory peptides from hydrolysates of marine shrimp A. chinensis. The novel peptides from hydrolysate of A. chinensis and some of their derived peptides with high ACE inhibitory activity probably have potential in the treatment of hypertension or in clinical nutrition.     

中国明对虾过氧化物还原酶基因在大肠杆菌中的重组表达、产物纯化及活性测定

过氧化物还原酶（Prx）是生物体内广泛存在的一类酶,在消除过氧化氢和抗氧化胁迫中起着重要的作用。本研究采用PCR扩增编码中国明对虾Prx成熟肽的基因,并克隆到大肠杆菌表达载体pCR®T7/NT TOPO® TA中进行体外重组表达。重组质粒转化大肠杆菌BL21 (DE3) pLysS后,经IPTG诱导表达产生包涵体形式的目的蛋白。对重组蛋白进行LC–ESI–MS分析,结果表明融合蛋白的四个肽段与中国明对虾Prx相应肽段完全一致。将重组蛋白通过金属螯合柱进行纯化,进而透析、复性,最后获得了具有较高过氧化物酶活性的重组Prx。中国明对虾Prx的成功表达,为深入研究其在中国明对虾免疫反应和抗氧化胁迫中的作用奠定了基础。     

虎纹蛙选择体温和热耐受性在个体发育过程中的变化

体温是影响变温动物表现的最重要生理学变量。检测了国家二级保护动物虎纹蛙的雌性亚成体、雄性亚成体、幼体和蝌蚪这4个发育阶段的选择体温和热耐受性。单因子方差分析表明,虎纹蛙选择体温、耐受低温、耐受高温和温度耐受范围的组间差异均显著,幼体的选择体温(24.13℃)显著低于雌性亚成体(28.06℃)、雄性亚成体(29.27℃)和蝌蚪(28.23℃),雌性亚成体、雄性亚成体和蝌蚪之间差异不显著;幼体的耐受低温(13.85℃)显著高于雌性亚成体(11.27℃)、雄性亚成体(10.84℃)和蝌蚪(10.74℃),雌性亚成体、雄性亚成体和蝌蚪之间差异不显著;幼体具有显著低的耐受高温(35.48℃)、蝌蚪具有显著高的耐受高温(43.31℃),雌性亚成体(39.55℃)和雄性亚成体(39.02℃)的耐受高温差异不显著;幼体(21.62℃)具有显著小的温度耐受范围、蝌蚪(32.58℃)具有显著大的温度耐受范围,雌性亚成体(28.28℃)和雄性亚成体(28.18℃)的温度耐受范围差异不显著。虎纹蛙幼体和亚成体体温和水温之间在降温速度和升温速度的相关关系均显著。用回归剩余值去除水温变化速度对体温变化的影响,双因子方差分析(降温和升温速度为重复检验设置)表明,幼体的体温变化速度显著大于亚成体,两性亚成体间差异不显著;温度变化类型(降温和升温)和两因子的交互作用对体温变化的影响不显著。基本热生态位分离和体温调节能力的发育限制是形成上述现象的最可能的原因。     

Recent population decline and selection shape diversity of taxol-related genes

Taxanes are defensive metabolites produced by Taxus species (yews) and used in anticancer therapies. Despite their medical interest, patterns of natural diversity in taxane-related genes are unknown. We examined variation at five main genes of Taxus baccata in the Iberian Peninsula, a region where unique yew genetic resources are endangered. We looked at several gene features and applied complementary neutrality tests, including diversity/divergence tests, tests solely based on site frequency spectrum (SFS) and Zeng's compound tests. To account for specific demography, microsatellite data were used to infer historical changes in population size based on an Approximate Bayesian Computation (ABC) approach. Polymorphism-divergence tests pointed to positive selection for genes TBT and TAT and balancing selection for DBAT. In addition, neutrality tests based on SFS found that while a recent reduction in population size may explain most statistics' values, selection may still be in action in genes TBT and DBAT, at least in some populations. Molecular signatures on taxol genes suggest the action of frequent selective waves with different direction or intensity, possibly related to varying adaptive pressures produced by the host-enemy co-evolution on defence-related genes. Such natural selection processes may have produced taxane variants still undiscovered.