Creation and analysis of a novel chimeric promoter for the complete containment of pollen- and seed-mediated gene flow

Effective containment of gene flow in transgenic plants requires a promoter that is highly specific for male and female gametes or tissues. Here, we report the creation of a novel pollen-, stigma- and carpel-specific (PSC) promoter through the fusion of the pollen-specific LAT52 and carpel-specific AGL5 enhancers to a stigma-specific SLG promoter. Gene expression analysis showed that fusion of the LAT52 enhancer to the SLG promoter enables the latter to gain pollen-specific activity while the acquirement of carpel-specific activity requires the correct orientation of the inserted AGL5 enhancer in the PSC promoter, and only a forward- but not a reverse-oriented one is functional. The resulting fPSC promoter, when fused to DT-A, generated at least three aberrant gynoecium phenotypes. Type I plants exhibited shortened stigmatic tissues, resembling plants containing the DT-A gene controlled by the SLG promoter. However, type II and III plants displayed partial or complete ablation of gynoecia, and were unable to support the reproductive process. Type II and III plants also produced severely perturbed anthers and pollen in comparison to type I or SLG::DT-A plants, and transgenic pollen grains were unable, when out-crossed with control plants, to pass the transgene to the next generation in all plants examined, indicating that they are selectively eliminated. This tissue-specific ablation or perturbation is highly specific, and does not compromise vegetative growth. Evidently, the fPSC promoter faithfully acquires tissue specificity from the incorporated enhancers and promoter, and should have a practical application for transgene containment in non-fruit and -grain producing plant crops.     

深海白色侧齿霉遗传转化体系建立及渗透压调控相关的EaSHO1基因功能

海洋中具有丰富的动植物及微生物资源,海洋真菌是其重要组成之一。我们前期的研究发现一株深海真菌白色侧齿霉Engyodontium album能产生具有抑菌活性的次级代谢产物engyodontiumin A,该化合物能抑制黑曲霉、金黄色葡萄球菌及创伤弧菌等病原菌的生长,是一种潜在的海洋源抗菌药物。目前,该菌遗传转化体系尚未建立,不利于开展次级代谢产物合成调控机制及其他功能基因研究。本研究成功制备了深海白色侧齿霉菌的原生质体,建立了借助聚乙二醇3350介导的原生质体转化体系,并将pCT74-sGFP载体成功导入白色侧齿霉的原生质体中,结果显示外源GFP能稳定表达。此外,为了明确白色侧齿霉菌是否能够开展基因敲除研究,通过氨基酸序列同源比对,我们选取酵母高渗甘油信号途径中的同源基因EaSHO1进行初步探究。利用同源重组的方法成功将目的基因EaSHO1的开放阅读框(ORF)替换成潮霉素磷酸转移酶基因(HPH),由此获得EaSHO1基因敲除突变体,并对突变体进行Southern杂交验证及初步的表型分析。结果表明,EaSHO1缺失不影响白色侧齿霉菌的营养生长及对高盐胁迫的响应,亚细胞定位结果显示EaS...     

Biocontrol Potential of Steinernema thermophilum and Its Symbiont Xenorhabdus indica Against Lepidopteran Pests: Virulence to Egg and Larval Stages

Under laboratory conditions, the biocontrol potential of Steinernema thermophilum was tested against eggs and larval stages of two important lepidopteran insect pests, Helicoverpa armigera and Spodoptera litura (polyphagous pests), as well as Galleria mellonella (used as a model host). In terms of host susceptibility of lepidopteran larvae to S. thermophilum, based on the LC₅₀ 36 hr after treatment, G. mellonella (LC₅₀ = 16.28 IJ/larva) was found to be more susceptible than S. litura (LC₅₀ = 85 IJ/larva), whereas neither host was found to be significantly different from H. armigera (LC₅₀ = 54.68 IJ/larva). In addition to virulence to the larval stages, ovicidal activity up to 84% was observed at 200 IJ/50 and 100 eggs of H. armigera and S. litura, respectively. To our knowledge this is the first report of entomopathogenic nematode pathogenicity to lepidopteran eggs. Production of infective juvenile (IJ) nematodes/insect larva was also measured and found to be positively correlated with rate of IJ for H. armigera (r = 0.990), S. litura (r = 0.892), as well as G. mellonella (r = 0.834). Both Phase I and Phase II of symbiotic bacteria Xenorhabdus indica were tested separately against neonates of H. armigera and S. litura by feeding assays and found to be virulent to the target pests; phase variation did not affect the level of virulence. Thus S. thermophilum as well as the nematode’s symbiotic bacteria applied separately have the potential to be developed as biocontrol agents for key lepidopteran pests.     

Phytoplankton composition,dominance and abundance as indicators of environmental compartmentalization in Jurumirim Reservoir (Paranapanema River), São Paulo,Brazil

Patterns in the spatial and temporal composition, dominance and abundance of the phytoplankton community of the Jurumirim Reservoir (Brazil) were studied during one year at ten different sampling stations. The main phytoplankton associations were characterized by diatoms and blue-green algae, in distinctive patterns of dominance. The main species were Microcystis aeruginosa Küetz, Anabaena circinalis Rabenhorst, A. spiroides Kleb., A. solitaria Kleb., Aulacoseira cf. italica Grunow and A. granulata (Ehr.) Simon. A high growth of Aulacoseira was observed in the upstream zones of the reservoir in spring, at the beginning of the seasonal rainy period. This growth was a response to increased flow rates and input of fresh nutrients by the main feeder rivers. A high concentration of blue-green algae, especially Anabaena circinalis and A. spiroides, was observed in winter (dry season) in the lacustrine part of the reservoir, towards the dam. These algae benefitted from the longer water retention times and greater internal circulation of nutrients in the absence of a thermocline at this time of the year. Among the Cyanophyceae, there was an alternation between M. aeruginosa, more abundant in summer, and Anabaena, dominant in autumn and winter. A conspicuous growth of Anabaena occurred in a diverticle of the reservoir, sheltered from the main advective processes that predominate in the central channel. Higher phytoplankton diversity was associated with the contact zone between riverine and lacustrine systems.     

Sequence and diversity of T-cell receptor alpha V, J, and C genes of the owl monkey Aotus nancymaae

 We cloned and sequenced TcR alpha chain cDNA of three healthy Aotus nancymaae monkeys. Fifteen different TRAJ segments and 9 different TRAV genes were identified in the 29 rearrangements analyzed. As expected from the greater phylogenetic distance, A. nancymaae TRA gene sequences diverged more from the human sequences than those of the chimpanzee or the rhesus macaque. However, no Aotus TRAJ segment or TRAV gene was found which lacked a human counterpart. These counterparts were AJ02, AJ05, AJ09, AJ15, AJ22, AJ23, AJ28, AJ30, AJ32, AJ34, AJ37, AJ40, AJ42, AJ45, AJ52 and AV2S1, AV2S3, AV3S1, AV8S1, AV12S1, AV15S1, ADV21S1/DV5, AV22S1S and AV23S1, respectively. In most cases the identity of amino acid sequences between corresponding Aotus and human genes was greater than 80%. This marked conservation of TRA gene sequences indicates a close structural relationship of Aotus and human TcR and demonstrates that the TcR repertoire in primates is remarkably stable. The results support the concept of using Aotus monkeys, which are susceptible to infection with the human malaria parasite Plasmodium falciparum, as an animal model for the evaluation of molecularly defined malaria vaccine candidates. Received: 15 January 1998 / Revised: 23 March 1998     

南亚热带丘陵赤红壤区农业可持续发展的土壤水分管理

南亚热带丘陵赤红壤地区水热资源丰富,可大力发展荔枝、龙眼、香蕉、芒果等岭南佳果基地和高效益的蔬菜的种植,是广东省以至全国的一块得天独厚的宝地.本文分析了南亚热带的自然概况、广东南亚热带地区的优势及丘陵赤红壤的特征.研究了广东省南亚热带丘陵赤红壤受气候因素的制约,土壤贮水库容和有效库容小,下层非饱和导水率及土壤水力扩散度低等水分特性及问题.提出了改善生态环境,利用生物或工程措施截流降雨、减少地表径流,提高降雨入流率从而增加土壤贮水量和有效贮水量,通过改良土壤,提高土壤保水性能和土壤供水能力,采取防止或减缓土壤水分蒸发措施,发展节水灌溉技术等土壤水分调控与管理技术措施.     

AmbiPack: A systematic algorithm for packing of macromolecular structures with ambiguous distance constraints

The determination of structures of multimers presents interesting new challenges. The structure(s) of the individual monomers must be found and the transformations to produce the packing interfaces must be described. A substantial difficulty results from ambiguities in assigning intermolecular distance measurements (from nuclear magnetic resonance, for example) to particular intermolecular interfaces in the structure. Here we present a rapid and efficient method to solve the packing and the assignment problems simultaneously given rigid monomer structures and (potentially ambiguous) intermolecular distance measurements. A promising application of this algorithm is to couple it with a monomer searching protocol such that each monomer structure consistent with intramolecular constraints can be subsequently input to the current algorithm to check whether it is consistent with (potentially ambiguous) intermolecular constraints. The algorithm AmbiPack uses a hierarchical division of the search space and the branch-and-bound algorithm to eliminate infeasible regions of the space. Local search methods are then focused on the remaining space. The algorithm generally runs faster as more constraints are included because more regions of the search space can be eliminated. This is not the case for other methods, for which additional constraints increase the complexity of the search space. The algorithm presented is guaranteed to find all solutions to a predetermined resolution. This resolution can be chosen arbitrarily to produce outputs at various level of detail. Illustrative applications are presented for the P22 tailspike protein (a trimer) and portions of β-amyloid (an ordered aggregate). Proteins 32:26–42, 1998. © 1998 Wiley-Liss, Inc.     

不同氮肥基追比例对高温胁迫下小麦籽粒产量和品质的影响

选用强筋小麦品种济麦20、烟农19、藁麦8901做试验材料,设置不同氮肥基追比例和籽粒灌浆中后期高温胁迫处理,研究了不同氮肥基追比例对高温胁迫条件下小麦籽粒产量和品质的影响.研究结果表明,追氮比例由50%增加到70%,3个品种的千粒重、籽粒产量、粗蛋白含量、湿面筋含量、醇溶蛋白含量、谷蛋白含量、HMW-GS含量、LMW-GS含量、HMW-GS/LMW-GS比值显著提高.济麦20和烟农19的谷蛋白大聚合体含量、谷蛋白大聚合体体积加权平均粒径和表面积加权平均粒径因追氮比例提高而升高, 藁麦8901则无显著变化.济麦20和烟农19的面团形成时间、面团稳定时间因追氮比例提高而延长, 藁麦8901基本不受影响.追氮比例由50%增加到70%,3个品种的籽粒支链淀粉/直链淀粉比值显著降低,淀粉糊化高峰黏度、低谷黏度、稀懈值、最终黏度和反弹值相应降低.总之,提高氮肥追施比例可在一定程度上缓解灌浆期高温胁迫对小麦粒重和蛋白质质量的不利影响,但对淀粉质量产生负面效应,且品种间存在差异.     

Syntheses and 1D structures of organic-inorganic hydrid polymers combining M(ClO4)2 (M = Cd, Zn) junctions and the semi-flexible bis-pyridyl ligand 3-pmpmd (N,N′-bis(3-pyridylmethyl)pyromellitic diimide)

Two 1D organic-inorganic coordination polymers, [Cd(3-pmpmd)(CH₃CN)₂(H₂O)₂]_n · 2n(ClO₄)₂ (1) and [Zn(3-pmpmd)_1.5(H₂O)₂]_n · 2n(ClO₄)₂ · nCH₃CN (2), were obtained from M(ClO₄)₂ (M = Cd, Zn) and the semi-flexible 3,3′-N-donor bis-pyridyl ligand 3-pmpmd: 1 has an 1D zigzag framework with 3-pmpmd in the Z_T-mode (anti, trans-) conformation, while 2 has an 1D rod and loop network with 3-pmpmd in both Z_T- and Z_C-mode (anti, cis-) conformations. Results showed that the metal ions could influence the coordination mode of a semi-flexible bis-pyridyl ligand.