长白落叶松生殖生物学特性研究──Ⅰ．球花芽分化与早期发育

本文研究了长白落叶松（ＬａｒｉｘｏｌｇｅｎｓｉｓＨｅｎｒｙ）大小孢子叶球的分化及其分布规律．获得如下结果：（１）６月下旬芽鳞形成期终止,７月初进入小孢子叶分化期,７月未至８月上旬小孢子叶分化期结束．８月上旬进入小孢子囊分化期,８月下旬出现造孢细胞,９月中旬形成小孢子母细胞．１０月底小孢子母细胞保持在细线期阶段,小孢子叶球进入冬季休眠期．（２）９月初苞片原基开始形成,９月中旬珠鳞原基形成;１０月上旬出现胚珠原始体,１０月下旬大孢子母细胞形成,１０月底大孢子叶球芽进入冬季休眠．（３）小孢子叶球芽主要分布在树冠的中、下部．数量上远远大于大孢子叶球芽的数量,约为大孢子叶球芽的１９倍。大孢子叶球芽主要集中分布在树冠中部,而且树冠下部多于树冠上部。     

RGDS肽对大鼠主动脉球囊内膜剥脱后血管壁增殖的影响

在大鼠主动脉球囊内膜剥脱术后血管壁细胞过度增殖模型上,用合成的血小板膜纤维蛋白原受体（ｇｌｙｃｏｐｒｏｔｅｉｎⅡｂ／Ⅲａｃｏｍｐｌｅｘ,ＧＰⅡｂ／Ⅲａ）拮抗剂ＲＧＤＳ（Ａｒｇ－Ｇｌｙ－Ａｓｐ－Ｓｅｒ,５０μｍｏｌ·ｋｇ－１·ｄ－１）治疗可有效地抑制损伤血管壁的细胞计数增加和内膜增厚以及血管平滑肌细胞增殖,显著降低其血管组织３Ｈ－ＴｄＲ和３Ｈ－Ｌｅｕ的参入增加程度。实验结果提示ＲＧＤＳ肽作为血管成型术的辅佐剂,对于防治血管再狭窄可能具有潜在的临床应用前景。     

丙型肝炎病毒RNA打点杂交检测方法同RT－PCR方法的比较

采用ＨＣＶ基因组结构区Ｃ区ｃＤＮＡ探针和非结构区ＮＳ３－４区ｃＤＮＡ探针,建立了用打点杂交（ｄｏｔｂｌｏｔｈｙｂｒｉｄｉｚａｔｉｏｎ）检测血清中ＨＣＶＲＮＡ的方法,同采用ＨＣＶ基因组５’端非编码区的一对寡核苷酸引物通过逆转录－聚合酶链式反应（ＲＴ－ＰＣＲ）检测血清中ＨＣＶＲＮＡ的方法相比较,发现两种方法都能快速早期和特异地检出血清中ＨＣＶＲＮＡ,但ＲＴ－ＰＣＲ法敏感性优于ＲＮＡ打点杂交法。对于无血清学指标的慢性ＮＡＮＢ肝炎病人的诊断,可采用这两种方法。这两种方法的敏感性在很大程度上依赖于引物和探针的敏感性,以及ＲＮＡ提取方法。ＲＴ－ＰＣＲ法适用于诊断病毒血症和复制,打点杂交法适用于研究ＨＣＶＲＮＡ量的变化,对治疗的评价,以及为实验筛选较高滴度的ＨＣＶＲＮＡ阳性样本。     

Isolation of two novel corrinoid proteins from acetate-grown Methanosarcina barkeri.

Two corrinoid proteins with molecular sizes of 480 and 29 kDa are stably methylated by [2-14C]acetate-derived intermediates in cell extracts of aceticlastic Methanosarcina barkeri when methylreductase is inhibited by the addition of bromoethanesulfonic acid. Both 14CH3-proteins have been isolated to near homogeneity and found to be abundant soluble proteins. The larger protein possesses two subunits, of 41.4 and 30.4 kDa, in an equimolar ratio, suggesting an alpha 6 beta 6 conformation with six bound methylated corrinoids per 480-kDa molecule. The 29-kDa protein is a monomer in solution and possesses only one methylated corrinoid. All methyl groups on both proteins are photolabile, but the methylated corrinoid bound to the 29-kDa protein undergoes photolysis at a higher rate than that bound to the 480-kDa protein. The two proteins possess discrete N termini and do not appear to be forms of the same protein in equilibrium. Neither protein has an Fe4S4 cluster, and both have UV-visible spectra most similar to that of a base-on methylated corrinoid. A previously identified methylated protein, designated the unknown A 14CH3-protein, copurifies with the 480-kDa protein and has the same subunit composition. The methyl groups of both isolated 14CH3-proteins are converted to methane in cell extracts. The methylated proteins that accumulate in extracts in the presence of bromoethanesulfonic acid are demethylated by the addition of coenzyme M. Both isolated proteins are abundant novel corrinoid proteins that can methylate and be methylated by intermediates of the methanogenic pathway.     

A new computational method for cable theory problems.

We discuss a new computational procedure for solving the linear cable equation on a tree of arbitrary geometry. The method is based on a simple set of diagrammatic rules implemented using an efficient computer algorithm. Unlike most other methods, this technique is particularly useful for determining the short-time behavior of the membrane potential. Examples are presented and the convergence and accuracy of the method are discussed.     

猫延髓吻侧腹外侧区NPY、SOM和NT免疫反应物质的分布

生理学研究表明,延髓吻侧腹外侧区(RVL)在维持血压稳定方面起着关键的作用。本文用免疫组化ABC技术,观察了猫RVL神经肽Y(NPY)、生长抑素(SOM)和神经降压肽(NT)免疫反应(IR)细胞和纤维的分布,以便为研究此区血压调节功能的机制提供形态学资料。结果表明:NPY—、SOM—IR细胞和少量NT—IR细胞主要分布于旁巨细胞外侧核、外侧网状核吻侧部以及外侧网状核背侧紧邻的网状结构。这些细胞从RVL尾侧向吻侧逐渐减少。NPY—IR纤维分布于旁巨细胞外侧核以及外侧网状核吻侧部的腹内侧区。NT—IR纤维较多,可见两丛中等密度的NT—IR纤维:一丛位于旁巨细胞外侧核;另一丛位于面后核、疑核以及二核紧邻的区域。此外还可见少量SOM—IR纤维。     

发酵乳杆菌CSC-19胞外粗多糖提取物抑制单核细胞增生李斯特菌生物被膜形成能力的研究

【目的】筛选能有效抑制单核细胞增生李斯特菌(Listeria monocytogenes,LM)形成生物被膜的乳酸菌,分析其活性成分并进行功能表征。【方法】采用结晶紫染色法筛选抑制LM形成生物被膜的不同乳酸菌提取物;通过酸中和、蛋白酶处理及热处理,推测抑制生物被膜活性物质以胞外多糖(extracellular crude polysaccharide,ECP)为主;乙醇沉淀法提取目标乳酸菌分离株胞外粗多糖,分析其抑制生物被膜形成活性和对LM生长的影响;运用激光共聚焦扫描显微镜(laser confocal scanning microscopy,LCSM)和扫描电子显微镜(scanning electron microscopy,SEM)观察胞外粗多糖对生物被膜细胞形态和结构的影响。【结果】发酵乳杆菌CSC-19发酵上清液对1516-2LM生物被膜的抑制率为81.7%;经热和蛋白酶处理后,发酵上清抑制生物被膜形成的活性未发生显著变化(P>0.05),表明发酵上清液中抑制生物被膜形成的物质可能为胞外多糖;在不抑制LM生长的条件下所提取的胞外粗多糖抑制生物被膜形成能力具有浓度依赖性。激光共聚焦扫描显微镜和扫描电子显微镜结果显示,胞外粗多糖显著抑制了生物被膜的形成能力,生物被膜三维、有组织的蜂窝状结构被破坏,仅有少量的粘附细胞分散于细胞爬片表面。【结论】发酵乳杆菌CSC-19胞外粗多糖能有效抑制LM生物被膜的形成,有望应用于高效防控该菌污染食品。     

Gut microbiome helps honeybee (Apis mellifera) resist the stress of toxic nectar plant (Bidens pilosa) exposure: Evidence for survival and immunity

Honeybee (Apis mellifera) ingestion of toxic nectar plants can threaten their health and survival. However, little is known about how to help honeybees mitigate the effects of toxic nectar plant poisoning. We exposed honeybees to different concentrations of Bidens pilosa flower extracts and found that B. pilosa exposure significantly reduced honeybee survival in a dose-dependent manner. By measuring changes in detoxification and antioxidant enzymes and the gut microbiome, we found that superoxide dismutase, glutathione-S-transferase and carboxylesterase activities were significantly activated with increasing concentrations of B. pilosa and that different concentrations of B. pilosa exposure changed the structure of the honeybee gut microbiome, causing a significant reduction in the abundance of Bartonella (p < 0.001) and an increase in Lactobacillus. Importantly, by using Germ-Free bees, we found that colonization by the gut microbes Bartonella apis and Apilactobacillus kunkeei (original classification as Lactobacillus kunkeei) significantly increased the resistance of honeybees to B. pilosa and significantly upregulated bee-associated immune genes. These results suggest that honeybee detoxification systems possess a level of resistance to the toxic nectar plant B. pilosa and that the gut microbes B. apis and A. kunkeei may augment resistance to B. pilosa stress by improving host immunity.     

TaTPP-7A positively feedback regulates grain filling and wheat grain yield through T6P-SnRK1 signalling pathway and sugar–ABA interaction

Grain size and filling are two key determinants of grain thousand-kernel weight (TKW) and crop yield, therefore they have undergone strong selection since cereal was domesticated. Genetic dissection of the two traits will improve yield potential in crops. A quantitative trait locus significantly associated with wheat grain TKW was detected on chromosome 7AS flanked by a simple sequence repeat marker of Wmc17 in Chinese wheat 262 mini-core collection by genome-wide association study. Combined with the bulked segregant RNA-sequencing (BSR-seq) analysis of an F₂ genetic segregation population with extremely different TKW traits, a candidate trehalose-6-phosphate phosphatase gene located at 135.0 Mb (CS V1.0), designated as TaTPP-7A, was identified. This gene was specifically expressed in developing grains and strongly influenced grain filling and size. Overexpression (OE) of TaTPP-7A in wheat enhanced grain TKW and wheat yield greatly. Detailed analysis revealed that OE of TaTPP-7A significantly increased the expression levels of starch synthesis- and senescence-related genes involved in abscisic acid (ABA) and ethylene pathways. Moreover, most of the sucrose metabolism and starch regulation-related genes were potentially regulated by SnRK1. In addition, TaTPP-7A is a crucial domestication- and breeding-targeted gene and it feedback regulates sucrose lysis, flux, and utilization in the grain endosperm mainly through the T6P-SnRK1 pathway and sugar–ABA interaction. Thus, we confirmed the T6P signalling pathway as the central regulatory system for sucrose allocation and source–sink interactions in wheat grains and propose that the trehalose pathway components have great potential to increase yields in cereal crops.     

Investigations of interaction mechanism and conformational variation of serum albumin affected by artemisinin and dihydroartemisinin

In this work, binding interactions of artemisinin (ART) and dihydroartemisinin (DHA) with human serum albumin (HSA) and bovine serum albumin (BSA) were investigated thoroughly to illustrate the conformational variation of serum albumin. Experimental results indicated that ART and DHA bound strongly with the site I of serum albumins via hydrogen bond (H-bond) and van der Waals force and subsequently statically quenched the intrinsic fluorescence of serum albumins through concentration-dependent manner. The quenching abilities of two drugs on the intrinsic fluorescence of HSA were much higher than the quenching abilities of two drugs on the intrinsic fluorescence of BSA. Both ART and DHA, especially DHA, caused the conformational variation of serum albumins and reduced the α-helix structure content of serum albumins. DHA with hydrophilic hydroxyl group bound with HSA more strongly, suggesting the important roles of the chemical polarity and the hydrophilicity during the binding interactions of two drugs with serum albumins. These results reveal the molecular understanding of binding interactions between ART derivatives and serum albumins, providing vital information for the future application of ART derivatives in biological and clinical areas.