植物非生物胁迫相关转录因子研究方法

转录因子是一类能够与启动子区域顺式作用元件特异性结合的蛋白质,是一大类转录调控因子,也是植物中最大的基因家族之一。转录因子可以调节众多下游基因的表达,对植物的生长发育、形态建成、激素调节,以及抵抗多种生物和非生物胁迫具有重要作用。结合近年来转录因子的研究进展,归纳总结了植物非生物胁迫相关转录因子研究的主要策略和方法,包括转录因子结构域、亚细胞定位、转录激活作用、转录因子复合体以及转录因子功能的研究,为植物转录因子的相关研究提供理论和方法的参考。     

Generation of active oxygen species (AOS) and induction of β-Glucanase activity by fungal elicitor xylanase in the suspension cultured cells of Tobacco

It was investigated that active oxygen species (AOS) involved in the plant defense responses induced by fungal elicitor xylanase. When xylanase from the fungusTrichoderma viridae was treated to tobacco suspension cultured cells as an elicitor, β-glucanase activity was increased markedly. Lignin biosynthesis was also increased and peaked at 72 h after the treatment with xylanase. The treatment of H₂O₂ also dramatically increased β-glucanase activity at 24 h, which was much earlier than that of xylanase did. Using lucigenin-and luminol-dependent chemiluminescence, the effects of xylanase on oxidative burst were examined. Superoxide anion (O₂) production was peaked at 40 h and 52 h after xylanase treatment and hydrogen peroxide (H₂O₂) release was peaked at 44 h and 56 h, suggesting H₂O₂ burst was followed by O₂ generation. The scavengers of AOS, n-propyl gallate (PG) and mannitol, inhibited xylanase-induced β-glucanase activity by 85% and 50%, respectively. The activity of superoxide dismutase (SOD), which catalyzes the dismutation of O₂ to H₂O₂, began to increase from 24 h and reached to maximum at 48 h after xylanase treatment. Pretreatment of N,N,-diethyldithiocarbamate (DDC), known as a SOD inhibitor, caused the inhibition of H₂O₂ generation by 80% and reduced the β-glucanase activity by 60%. Treatment of 2,5-norbonadiene (NBD), a specific ethylene-action inhibitor, did not have any significant effect on xylanase-induced β-glucanase activity. This result suggested that ethylene did not involve in xylanase-induced response. Our results strongly suggest that the AOS generation is an essential component in plant defense response, in which cell wall degrading enzyme, glucanase, contributes to remove the necrotic tissue induced by pathogens.     

遥感数据支持下不同地表覆盖的区域蒸散

将地表能量平衡系统(SEBS)扩展成遥感日蒸散估算模型,利用MODIS遥感数据估算了黄淮海地区的区域蒸散,并在地理信息系统的支持下分析了不同地表覆盖下的区域蒸散统计分布特征.在缺乏各地表覆盖类型相应蒸散量实测值进行对比的情况下,以2001年4月17日估算的日蒸散量为例,通过各地表覆盖类型日蒸散量间的相互对比分析表明,SEBS估算的区域日蒸散量具有一定的合理性.分析结果表明：在黄淮海地区,荒地具有最低的蒸散量;森林、灌木、草地等地表覆盖类型具有中等的蒸散量;而水体、湿地以及耕地具有较高的蒸散量.可能由于包含绿地和水面,城镇用地的蒸散量也较高.土壤含水量的空间差异性导致森林、灌木、草地和耕地等地表覆盖类型的蒸散量具有明显的空间差异性.耕地蒸散量的空间差异性可以为制定合理、高效的农田灌溉计划提供指示作用.SEBS遥感日蒸散模型的局限性在于有可能低估水体和湿地等地表覆盖类型的蒸散量.     

Improved synthesis of 2′-deoxyadenosine and 5-methyluridine by Escherichia coli using an auto-induction system

Nucleoside analogues are used widely for the treatment of viral diseases and cancer, however the preparation of some important intermediates of these nucleoside analogues, including 2′-deoxyadenosine (dAR) and 5-methyluridine (5-MU), remains inconvenient. To optimize the synthesis of dAR and 5-MU, recombinant strains and auto-induction medium were employed in this study. E. coli BL21(DE3) strains overexpressing purine nucleoside phosphorylase (PNP), uridine phosphorylase (UP) and thymidine phosphorylase (TP) were constructed and cultured in auto-induction ZYM-Fe-5052 medium for 8 h. The cultures of these strains were then used directly to synthesize dAR and 5-MU. Under optimized conditions, 30 mM adenine was converted to 29 mM dAR in 1 h, and 32 mM 5-MU was obtained from 60 mM thymine, using 6% (v/v) cell solutions as biocatalysts. These results indicate that our convenient and efficient method is ideal for the preparation of dAR and 5-MU, and has potential for the preparation of other nucleoside analogue intermediates.     

Hydrogen-induced tolerance against osmotic stress in alfalfa seedlings involves ABA signaling

Plant and Soil - Cadmium (Cd) is a toxic metal in soils and its accumulation in plants poses severe problems to agricultural production and human health. Most of research has focused on the Cd...     

Derivatives of 1-(2-Deoxy-2-fluoro-β-D-arabinofuranosyl)-5-phenyluracil and 5-Benzyluracil. Synthesis and Biological Properties

Abstract

A number of 1-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)uracil and -cytosine nucleosides substituted at the 5 position with a nitrophenyl or nitrobenzyl group were synthesized from 5-phenyl- and 5-benzyluracil via condensation of the fluorinated sugar, followed by nitration. The corresponding amino analogues were also prepared by reduction of the nitro nucleosides. The uracil nucleosides were converted into the corresponding cytosine nucleosides by way of the triazole intermediates. None of these nucleosides exhibited significant activity against herpes simplex virus type 1 in Vero cells. However, cytosine nucleosides containing the o-nitrophenyl, p-nitrophenyl, p-nitrobenzyl or p-aminobenzyl substituent were found to be toxic (even at 1 μM) to uninfected Vero cells, although they were essentially nontoxic in HL-60 cells. The 5′-monophosphates of the uracil nucleosides were inhibitors of the reaction catalyzed by purified Ehrlich ascites carcinoma thymidylate synthase, the 5-phenyluracil nucleotides causing a strong inhibition, competitive vs dUMP, described by the K_i value of 0.01 μM.     

Glycoforms of UT-A3 urea transporter with poly-N-acetyllactosamine glycosylation have enhanced transport activity

Urea transporters UT-A1 and UT-A3 are both expressed in the kidney inner medulla. However, the function of UT-A3 remains unclear. Here, we found that UT-A3, which comprises only the NH(2)-terminal half of UT-A1, has a higher urea transport activity than UT-A1 in the oocyte and that this difference was associated with differences in N-glycosylation. Heterologously expressed UT-A3 is fully glycosylated with two glycoforms of 65 and 45 kDa. By contrast, UT-A1 expressed in HEK293 cells and oocytes exhibits only a 97-kDa glycosylation form. We further found that N-glycans of UT-A3 contain a large amount of poly-N-acetyllactosamine. This highly glycosylated UT-A3 is more stable and is enriched in lipid raft domains on the cell membrane. Kifunensine, an inhibitor of α-mannosidase that inhibits N-glycan processing beyond high-mannose-type N-glycans, significantly reduced UT-A3 urea transport activity. We then examined the native UT-A1 and UT-A3 glycosylation states from kidney inner medulla and found the ratio of 65 to 45 kDa in UT-A3 is higher than that of 117 to 97 kDa in UT-A1. The highly stable expression of highly glycosylated UT-A3 on the cell membrane in kidney inner medulla suggests that UT-A3 may have an important function in urea reabsorption.     

Development and characterization of 79 nuclear markers amplifying in viviparous and oviparous clades of the European common lizard

The European common lizard (Zootoca vivipara) is a widely distributed species across Europe and Asia exhibiting two reproductive modes (oviparity/viviparity), six major lineages and several sublineages. It has been used to tackle a large variety of research questions, nevertheless, few nuclear DNA sequence markers have been developed for this species. Here we developed 79 new nuclear DNA sequence markers using a clonation protocol. These markers were amplified in several oviparous and viviparous specimens including samples of all extant clades, to test the amplification success and their diversity. 49.4% of the markers were polymorphic and of those, 51.3% amplified in all and 94.9% amplified in 5–7 of the extant Z. vivipara clades. These new markers will be very useful for the study of the population structure, population dynamics, and micro/macro evolution of Z. vivipara. Cross-species amplification in four lizard species (Psammodromus edwardsianus, Podarcis muralis, Lacerta bilineata, and Takydromus sexlineatus) was positive in several of the markers, and six makers amplified in all five species. The large genetic distance between P. edwardsianus and Z. vivipara further suggests that these markers may as well be employed in many other species.