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。     

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.     

黑叶猴和灰叶猴的线粒体DNA限制性片段长度多态研究

本文以15种限制性内切酶分析黑叶猴和灰叶猴种内及种间mtDNA多态。从各个样品中分别检出了41—50个酶切位点。综合15种限制内酶的酶切类型,在2只黑叶猴和2只灰叶猴中分别检出了两种限制性类型,并与其4个地理来源相对应。结合恒河猴和红面猴的资料,构建了4种猴科动物的分子系统树。结果表明,黑叶猴和灰叶猴种内的分歧分别始于30和35万年以前,两种叶猴的分离始于190万年以前,猴亚科和疣猴亚科的分离应早于1100万年。叶猴属在中国的扩散不是很晚才发生的。     

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。     

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.     

Inhibitory role of bone marrow mesenchymal stem cells-derived exosome in non-small-cell lung cancer: microRNA-30b-5p,EZH2 and PI3K/AKT pathway

Exosomal microRNA (miRNA) exerts potential roles in non-small-cell lung cancer (NSCLC). The current study elucidated the role of miR-30b-5p shuttled by bone marrow mesenchymal stem cells (BMSCs)-derived exosomes in treating NSCLC. Bioinformatics analysis was performed with NSCLC-related miRNA microarray GSE169587 and mRNA data GSE74706 obtained for collection of the differentially expressed miRNAs and mRNAs. The relationship between miR-30b-5p and EZH2 was predicted and confirmed. Exosomes were isolated from BMSCs and identified. BMSCs-derived exosomes overexpressing miR-30b-5p were used to establish subcutaneous tumorigenesis models to study the effects of miR-30b-5p, EZH2 and PI3K/AKT signalling pathway on tumour growth. A total of 86 BMSC-exo-miRNAs were differentially expressed in NSCLC. Bioinfomatics analysis found that BMSC-exo-miR-30b-5p could regulate NSCLC progression by targeting EZH2, which was verified by in vitro cell experiments. Besides, the target genes of miR-30b-5p were enriched in PI3K/AKT signalling pathway. Animal experiments validated that BMSC-exo-miR-30b-5p promoted NSCLC cell apoptosis and prevented tumorigenesis in nude mice via EZH2/PI3K/AKT axis. Collectively, the inhibitory role of BMSC-derived exosomes-loaded miR-30b-5p in NSCLC was achieved through blocking the EZH2/PI3K/AKT axis.     

酶法生产L-高苯丙氨酸的研究进展

L-高苯丙氨酸(L-homophenylalanine,L-HPA)作为一种重要的非天然氨基酸,是合成治疗高血压的普利类药物等的关键中间体,具有广阔的市场前景。目前L-高苯丙氨酸的合成主要依赖于化学法,但化学合成L-高苯丙氨酸具有原料昂贵、步骤繁琐和污染严重等缺点,限制了广泛应用。因此,国内外研究者对L-高苯丙氨酸的酶法生产进行了深入的研究。本文就目前酶法合成L-高苯丙氨酸的工艺,包括脱氢酶法、转氨酶法、海因酶法和脱羧酶法的研究进展进行了综述,为酶法合成L-高苯丙氨酸提供一定的借鉴,为最终实现L-高苯丙氨酸的酶法工业化生产奠定基础。