臭氧胁迫下硅对大豆抗氧化系统、生物量及产量的影响

在全球变化情景下,臭氧污染对作物产量将造成严重影响,臭氧将成为未来农业重要胁迫因素。研究缓解臭氧胁迫技术措施有利于保障粮食安全,其中硅元素添加可能是有效途径之一。利用开顶式同化箱(open top chambers,OTCs)装置,设置两个O3浓度(大气O3浓度<40μg/kg和高O3浓度约为80μg/kg)、两个硅浓度(0和100μg/g),研究不同O3浓度下硅对开花后大豆(Glycine max)株高、叶面积、叶绿素含量、抗氧化系统及产量的影响。结果表明:在无臭氧胁迫下,施硅可显著提高大豆根生物量、总生物量和单株籽粒重(14%、5%和20%)(P<0.05)。在O3胁迫下,施硅能使大豆维持较高的叶面积,显著提高大豆叶片叶绿素含量及SOD、POD、CAT活性,显著降低MDA含量,提高大豆根生物量、地上部生物量、总生物量、根冠比和单株籽粒重(29%,18%,19%,9%和17%)(P<0.05)。研究可为缓解O3对大豆危害提供合理可行的栽培管理措施与理论依据。     

基于临界氮浓度的小麦地上部氮亏缺模型

基于3年的大田试验,选择代表性的中蛋白小麦品种（扬麦16）和低蛋白小麦品种（宁麦13）,分别构建了小麦地上部干物质临界氮浓度(N_cnc)稀释曲线模型、氮营养指数（NNI）模型和氮亏缺(N_and)模型.结果表明： 小麦地上部干物质临界氮浓度稀释曲线模型具有明确的生物学意义,小麦临界氮浓度与地上部最大干物质（DM）符合幂函数关系（扬麦16为N_cnc=4.65DM^-0.44;宁麦13为N_cnc=4.33DM^-0.45）;小麦地上部氮营养指数模型可以准确诊断氮素营养状况;小麦地上部氮亏缺模型可以定量调控氮肥管理措施.利用2007-2008年的独立试验资料对小麦地上部干物质临界氮浓度稀释模型、氮营养指数模型和氮亏缺模型进行检验和测试,结果表明模型的准确性较高,普适性较强.本文所构建模型可以直接用于诊断调控小麦氮素营养,为小麦生产中精确施肥管理提供了较好的技术途径和理论基础.     

Plastid and nuclear phylogenomic incongruences and biogeographic implications of Magnolia s.l. (Magnoliaceae)

Magnoliaceae, an assemblage of early diverged angiosperms, comprises two subfamilies, speciose Magnolioideae with approximately 300 species in varying numbers of genera and monogeneric Liriodendroideae with two species in Liriodendron L. This family occupies a pivotal phylogenetic position with important insights into the diversification of early angiosperms, and shows intercontinentally disjunct distribution patterns between eastern Asia and the Americas. Widespread morphological homogeneity and slow substitution rates in Magnolia L. s.l. resulted in poorly supported phylogenetic relationships based on morphology or molecular evidence, which hampers our understanding of the genus’ temporal and spacial evolution. Here, based on the newly generated genome skimming data for 48 Magnolia s.l. species, we produced robust Magnolia phylogenies using genome-wide markers from both plastid genomes and single nucleotide polymorphism data. Contrasting the plastid and nuclear phylogenies revealed extensive cytonuclear conflicts in both shallow and deep relationships. ABBA-BABA and PhyloNet analyses suggested hybridization occurred within sect. Yulania, and sect. Magnolia, which is in concordance with the ploidy level of the species in these two sections. Divergence time estimates and biogeographic reconstruction indicated that the timing of the three tropical Magnolia disjunctions coincided with the mid-Eocene cooling climate and/or late Eocene climate deterioration, and two temperate disjunctions occurred much later, possibly during the warm periods of the Miocene, hence supporting the boreotropical flora concept of Magnolia s.l.     

产气荚膜梭菌α毒素在干酪乳杆菌中的诱导表达及小鼠口服免疫保护效力的测定

摘要: 【目的】构建产气荚膜梭菌（Clostridium perfringens, C．perfringens）α 毒素基因的重组干酪乳杆菌口服疫苗,为产气荚膜梭菌毒素中毒的防治提供有效方法。【方法】将构建的重组产气荚膜梭菌α毒素基因细胞表面型载体pPG1及分泌表达载体pPG2电转化乳酸乳杆菌（Lactobacillus casei L.casei）,获得阳性重组菌pPG1-α/ L.casei 393 乳酸乳杆菌表面表达系统和pPG2-α/ L.casei393乳酸乳杆菌分泌表达系统。重组菌以1%乳糖为诱导物,在MRS培养基中进行诱导,通过Western-blot和间接免疫荧光方法鉴定,确定目的蛋白的表达。将重组菌口服免疫BALB/c小鼠,收集免疫小鼠粪便及眼冲洗液及外生殖道黏液样本测定小鼠产生抗α毒素的特异性sIgA 抗体水平,采集小鼠血液样本测定血清中抗α毒素的特异性IgG抗体水平。并对免疫小鼠进行α毒素的腹腔攻毒实验及对获得的抗血清进行α毒素中和试验测定。【结果】重组干酪乳杆菌pPG1-α/ L.casei 393及pPG2-/ L.casei 393免疫小鼠能够产生明显的抗α毒素的sIgA 和IgG 抗体水平,其对α毒素中和试验结果为完全保护。腹腔攻毒实验结果为能抵抗3倍最小致死剂量的α毒素攻击。【结论】表达产气荚膜梭菌α毒素免疫保护性抗原的重组乳酸乳杆菌口服免疫动物能够产生良好的局部和系统体液免疫应答和免疫中和效力。     

Metabolomic profiling of three brain regions from a postnatal infected Borna disease virus Hu-H1 rat model

Neonatal rat infection with Borna disease virus (BDV), termed neonatal Borna disease, is an established model for investigating the BDV-associated pathogenesis of neurodevelopmental abnormalities. BDV produces a persistent noncytolytic infection in all culture cell systems assayed to date, while persistent infection in neonatal rats results in a progressive loss of hippocampal granule cells, cerebellar Purkinje cells, and cortical GABA-ergic neurons. Persistent infection also results in behavioral deficits including hyperactivity, cognitive impairment, and abnormal social behavior. However, the molecular mechanisms underlying the neuronal degeneration and behavioral abnormalities remain unclear. Using a metabolomic approach based on gas chromatography coupled with mass spectrometry in conjunction with statistical pattern recognition, the metabolic changes in response to BDV Hu-H1 infection were characterized in the rat hippocampus, cerebellum, and cortex. Metabonomic profiling revealed significant perturbations in nucleotide (e.g., adenosine, uracil, inosine, adenosine-5′-monophosphate, uridine-5′-monophosphate, d-ribose 5-phosphate, and sedoheptulose 7-phosphate), amino acid (e.g., lysine, glycine, phenylalanine, tyrosine, proline, serine, cysteine, aspartic acid, pyroglutamic acid, and γ-aminobutyric acid), lipid (e.g., cholesterol, myristic acid, stearic acid, palmitic acid, 1-monopalmitoylglycerol, and arachidonic acid), and energy (e.g., glucose, lactose, 3-phosphoglyceric acid, and pyruvic acid) metabolites. These metabolites participate in pathways crucial to viral proliferation and neurotransmitter homeostasis. This metabolomic profiling study provides insight into the pathogenic mechanisms of BDV and new directions with which to investigate the in vivo effects of persistent BDV infection.     

植物对土壤中铀的吸收与富集

核工业发展导致重金属铀排放和扩散,并造成了地表土壤的污染,对人类的生存环境产生了极其不利的影响。如何修复铀污染土壤成为亟待解决的问题。近年来发展起来的植物修复技术以其成本低廉、安全和环保的特点成为修复铀污染土壤的新选择。寻找理想的铀富集植物是这一技术的基础和关键。该文通过实验模拟铀污染的土壤（土壤中铀的浓度为100 mg.kg–1）,进行一次和二次铀污染土壤的植物修复后,从4个方面对植物修复铀污染土壤效果进行评估,即富集铀的浓度、生物提取量、生物富集系数（BFS）和转运系数（TFS）。实验结果表明：第1次修复时,四季香油麦菜（Lactuca dolichophylla）地上部富集铀的浓度为1.67×103 mg.kg–1,生物富集系数和转移系数均大于3;第2次修复时,麦冬（Ophiopogon japoni-cus）富集铀的浓度与第1次修复相比变化不大,而吊兰（Chlorophytum comosum）、四季豆（Phaseolus vulgaris）和艾蒿（Artemisia lavandulaefolia）富集铀的浓度与第1次修复相比均减少4–8倍;施加土壤改良剂鸡粪肥、海藻肥和柠檬酸后发现海藻肥和柠檬酸能够增强植物对铀污染土壤的修复;对两次修复土壤中铀的形态进行对比分析,发现二次修复时土壤中生物有效态铀的含量降低,造成第2次修复的难度增加。     

解淀粉芽胞杆菌启动基因的克隆及其对地衣杆菌α-淀粉酶基因的调控

用大肠杆菌启动基因探针质粒pHE5克隆了解淀粉芽胞杆菌的启动基因。供体菌DNA的HindⅢ片段与pHE5重组后转化大肠杆菌,获得一批带启动基因的抗四环素转化子,其中四株的抗性达到200μg/mL,从这四株高抗性转化子中提取质粒,并对其中的一个重组质粒pAE23的插入片段进行限制性图谱分析和缺失研究,获得了一个缺失了部份片段,四环素抗性仍达到200μg/mL的衍生质粒pAED23,经酶切分析证明其上的启动基因位于0.8kb的EcoR Ⅰ—HindⅢ片段上。点杂交分析证实该片段来自解淀粉芽胞杆菌的DNA。将地衣杆菌的α-淀粉酶基因亚克隆至pAED23启动基因下游的HindⅢ位点上能增强该基因在大肠杆菌中的表达。