光枝勾儿茶内生真菌多样性及抑菌活性研究

为探索贵州苗药光枝勾儿茶内生真菌类群特征、分布部位及其抑菌活性,该研究采用传统方法对贵州省贵阳市和黔西市光枝勾儿茶内生真菌进行分离,并基于分子生物学及统计学对其分类地位进行鉴定及多样性评价,最后通过微量肉汤倍比稀释法筛选具有抑菌活性的菌株。结果表明:(1)从光枝勾儿茶中分离到191 株内生真菌,隶属于3 个门5 个纲10 个目15 个科19 个属,优势属为叶点霉属(Phyllosticta)、间座壳属(Diaporthe)、葡萄座腔菌属(Botryosphaeria)和刺盘孢属(Colletotrichum)。(2)黔西光枝勾儿茶内生真菌香农-维纳多样性指数(H''_Q=2.112)较贵阳(H''_G=1.801)高,索伦森相似性指数Cs_G-Q为0.923,不同组织香农-维纳多样性指数为茎(H''_S=2.004)>根(H''_R=1.764)>叶(H''_L=1.654)>果实(H''_F=1.473),茎和叶内生真菌的索伦森相似性最高(Cs_S-L=0.667)。(3)筛选出的21株内生真菌对供试菌大肠杆菌(Escherichia coli)、金黄色葡萄球菌(Staphylococcus aureus)和沙门氏菌(Salmonella enterica)具有抑菌效果,其中Diaporthe sp. QX4G6对大肠杆菌、金黄色葡萄球菌和沙门氏菌的最小抑菌浓度分别为12.5、6.25、12.5 mg·mL^-1,最小杀菌浓度分别为12.5、6.25、12.5 mg·mL^-1。以上研究结果揭示了光枝勾儿茶蕴藏丰富的内生真菌资源,不同地区及组织内生真菌类群组成有差异,多个分离菌株具有抗菌活性,为光枝勾儿茶内生真菌天然抗菌药物或药源研发奠定了基础。     

三疣梭子蟹卵巢发育过程中主要类胡萝卜素组成变化及其与抗氧化性能的关系

实验研究了三疣梭子蟹(Portunus trituberculatus)卵巢发育过程中(Ⅰ—V期)组织色泽、类胡萝卜素组成与含量、抗氧化和非特异性免疫指标的变化规律,进一步探讨了肝胰腺中类胡萝卜素含量变化与抗氧化指标的关系。结果表明:(1)卵巢发育期间,卵巢指数(GSI)显著增加(P<0.05),肝胰腺指数(HSI)整体呈先升后降的趋势;卵巢的红度(a*)值和黄度(b*)值、肝胰腺的亮度(L*)值和b*值均呈显著上升趋势,但卵巢中L*值呈下降趋势。(2)在卵巢发育过程中,卵巢中的总类胡萝卜素、虾青素、叶黄素和β-胡萝卜素含量均为先升后降的趋势,虾青素含量在Ⅳ期最高;肝胰腺中的虾青素含量呈上升趋势,而β-胡萝卜素含量为显著下降趋势;内表皮中的总类胡萝卜素、虾青素、叶黄素、海胆烯酮和β-胡萝卜素含量均呈现下降趋势;就不同组织中类胡萝卜素含量而言,内表皮中虾青素含量最高。卵巢和肝胰腺的L*值与总类胡萝卜素含量呈显著负相关,卵巢的a*值和b*值均与总类胡萝卜素、虾青素、叶黄素、海胆烯酮和β-胡萝卜素含量呈显著正相关。肝胰腺的a*值与各类胡萝卜素含量无显著相关性, b*值仅与虾青素含量呈显...     

色氨酸阻遏物与其操纵基因复合物的圆二色性研究

用圆二色性谱来确定色氨酸阻遏物与其操纵基因复合物在溶液中的构象变化。色氨酸阻遏物的圆二色性图谱表明它是一种富含α螺旋的蛋白质,通过比较加入Ｌ－Ｔｒｐ前和后的圆二色性谱,发现活性的与非活性的色酸阻遏物二级结构变化很小,ｔｒｐ Ｐ／Ｏ的圆二色性谱与它的单健、双链理论计算曲线对比,可近拟推测操纵基因在溶液中的存在状态。用色氨酸阻遏物对ｔｒｐ Ｐ／Ｏ进行确定,可以从中找出蛋白质与核酸结合的平衡点。从平衡时     

棉纤维发育过程中细胞壁超微结构变化的研究

应用X射线衍射法研究了棉纤维发育过程中细胞壁超微结构变化的动态规律.其结果是:次生壁S_2层的平均微纤丝螺旋角随花后生长天数的增加而逐渐变小:纤维素微晶粒间的取向度逐渐变大;花后5—14天内,结晶度缓慢增加,14—17天内陡然增加,17天后缓慢趋向最大值.     

不同配体与同一膜受体结合的初步探讨

研究了伴刀豆球蛋白A(ConA)和层粘连蛋白(LN)与巨噬细胞膜受体竞争结合,初步推测两个配体与同一膜受体结合的可能性.结果表明,LN可以竞争抑制FTTC-ConA与巨噬细胞膜受体的结合,说明ConA和LN两种配体各自的巨噬细胞膜受体中有部分可能是共同的,而加入ConA反而增加巨噬细胞膜上结合的FITC-LN量,这可能是因为ConA和LN的分子特性导致的.     

细胞分裂素在离体蒜苔内的运转

离体蒜苔饲喂带~3H 标记的6-苄基腺嘌呤(BA)后在暗中25℃下放置,分别在第3、5、10、15、20天取样,进行放射性物质的分布分析。结果表明:(1)BA 能沿着苔茎大量、长距离地上运,并在顶端的珠蒜中积累;(2)BA 的这种运转具有很强的向顶极性;(3)这种运转是一个平缓而稳定的过程,珠蒜中 BA 的积累与时间成较好的线性关系;(4)顶端的珠蒜对 BA 的上运是必不可少的。根据以上结果,本文对蒜苔内 BA 的运转机理及意义进行了讨论。     

变黄黑文衣,中国黑文衣属地衣一新记录种

通过对文字衣科黑文衣属形态学、解剖学、化学与分子生物学的研究,发现中国新记录种1种,即变黄黑文衣(Phaeographis flavescens Dal-Forno&Eliasaro),该种主要特征为地衣体壳状,表面浅黄绿色,无光泽,光滑;子囊盘弯曲,多分支,聚生于假子座中;盘缘黑色,相邻线盘之间有小缝隙,盘面较平坦,黑色,覆有白色粉霜;子囊层无色透明,侧丝顶端分支;子囊含8个子囊孢子;子囊孢子褐色,横隔透镜型,(4～)6胞室,大小19～25.5μm×6～7μm,I+紫红色。该种分布于云南和福建,该研究丰富了对中国黑文衣属物种组成与分布的认知。     

High-Resolution Performance of Polycaprolactone Functionalized with Guanidinium Ionic Liquid for Gas Chromatography

This work firstly reported a new polycaprolactone based material functionalized with guanidinium ionic liquid (PCL-GIL) as the stationary phase with high resolution performance for capillary gas chromatography (GC). It is composed of polycaprolactone (PCL) and guanidinium ionic liquid (GIL) with amphiphilic conformation. The PCL-GIL capillary column coated by static method exhibited high column efficiency of 3942 plates/m and moderate polarity. As a result, the PCL-GIL column exhibited high-resolution capability. For a mixture of 27 analytes with a wide ranging polarity and outperformed the PCL-2OH and HP-35 columns, showing its advantageous separation capability for analytes of diverse types. Moreover, the PCL-GIL column showed high resolving capability for various positional isomers and cis-/trans-isomers, including alkylbenzenes, chlorobenzenes, naphthalenes, bromonitrobenzenes, chloronitrobenzenes, benzaldehydes, phenols, alcohols, respectively. In a word, PCL derivatized by GIL units as a new type of stationary phase has a promising future in GC separations.     

珍稀濒危植物峨眉含笑种实表型性状的空间变异特征

通过分析珍稀濒危植物峨眉含笑（Michelia wilsonii）种子与果实的表型性状特征,研究其变异规律和空间自相关性,为峨眉含笑天然种群的保护利用工作提供依据。以雅安周公山的峨眉含笑为研究对象,测定12项种实表型性状指标,采用变异系数和半方差函数,探究峨眉含笑种实的空间变异特征。结果显示：（1）峨眉含笑种实表型性状的平均变异系数为27.59%,种实的形态变异程度最小,种子性状的变异程度比果实性状更为丰富。（2）聚合果下部的种子败育率与蓇葖败育率最高,分别为18.32%和38.22%;中部的败育率最低,分别为15.05%和23.45%。（3）半方差函数模型以指数和球状模型为主,呈聚集分布。除果实长、种子纵径和种子败育率外,其余9项指标具有中高等强度的空间自相关性。（4）9项指标的各向异性比接近于1,空间异质性表现为各向同性。因此,峨眉含笑种实表型性状在中等尺度的空间范围内具有丰富的变异性。     

A short-chain carbonyl reductase mutant is an efficient catalyst in the production of (R)-1,3-butanediol

R-1,3-butanediol (R-1,3-BDO) is an important chiral intermediate of penem and carbapenem synthesis. Among the different synthesis methods to obtain pure enantiomer R-1,3-BDO, oxidation–reduction cascades catalysed by enzymes are promising strategies for its production. Dehydrogenases have been used for the reduction step, but the enantio-selectivity is not high enough for further organic synthesis efforts. Here, a short-chain carbonyl reductase (LnRCR) was evaluated for the reduction step and developed via protein engineering. After docking result analysis with the substrate 4-hydroxy-2-butanone (4H2B), residues were selected for virtual mutagenesis, their substrate-binding energies were compared, and four sites were selected for saturation mutagenesis. High-throughput screening helped identify a Ser154Lys mutant which increased the catalytic efficiency by 115% compared to the parent enzyme. Computer-aided simulations indicated that after single residue replacement, movements in two flexible areas (VTDPAF and SVGFANK) facilitated the volumetric compression of the 4H2B-binding pocket. The number of hydrogen bonds between the stabilized 4H2B-binding pocket of the mutant enzyme and substrate was higher (from four to six) than the wild-type enzyme, while the substrate-binding energy was decreased (from −17.0 kJ/mol to −29.1 kJ/mol). Consequently, the catalytic efficiency increased by approximately 115% and enantio-selectivity increased from 95% to 99%. Our findings indicate that compact and stable substrate-binding pockets are critical for enzyme catalysis. Lastly, the utilization of a microbe expressing the Ser154Lys mutant enzyme was proven to be a robust process to conduct the oxidation–reduction cascade at larger scales.