东方山羊豆水通道蛋白基因的克隆及初步分析

根据已知EST片段结合RT-PCR和RACE技术,从东方山羊豆(Galega Orientalis)中克隆到一个水通道蛋白(AQP)基因,命名为GoAQP(GenBank登录号:HM 803185)。测序和生物信息学分析表明,此序列全长1258bp,开放读码框(ORF)870 bp,编码289个氨基酸。GoAQP包含MIP家族信号序列HINPAVT/SFG,高等植物PIP高度保守序列GGANXXXXGY和TGI/TNPARSL/FGAAI/VI/VF/YN。与拟南芥AQP基因家族的系统进化分析表明,GoAQP属于PIP1亚型AQP蛋白。Real-Time PCR检测结果表明,GoAQP基因在根中表达量最高,茎中表达量最少;且受NaCl和PEG胁迫表达上调,NaCl表达呈双峰分布。因此GoAQP基因可能参与了东方山羊豆耐盐性调控。同时成功构建超表达载体pCAMBIA-1302-GoAQP,为转基因验证基因功能创造了基础。     

Determinants for successful reforestation of abandoned pastures in the Andes: Soil conditions and vegetation cover

The Andes of Ecuador are known for their outstanding biodiversity but also as the region with the highest deforestation rate in South America. This process is accompanied by accelerating degradation and loss of environmental services. Despite an extraordinary richness in native tree diversity, more than 90% of all forest plantations established in Ecuador consist of exotic species, primarily Eucalyptus spp. and Pinus spp. This is mainly due to the lack of information about the autecological and synecological requirements of the native species.     

Application of mycorrhizal roots improves growth of tropical tree seedlings in the nursery: a step towards reforestation with native species in the Andes of Ecuador

Most tree species in tropical mountain rain forests are naturally associated with arbuscular mycorrhizal fungi. Previous studies in southern Ecuador of 115 tree species revealed that only three species were not associated with arbuscular mycorrhizal fungi. Seedlings of tropical tree species raised in the nursery may need to be associated with arbuscular mycorrhizal fungi to survive transplantation shock in higher numbers. Methods for establishing plantations with native tree species are not yet established for Ecuador. Thus, we investigated the feasibility of using mycorrhizal roots of seedlings of Inga acreana, Tabebuia chrysantha, Cedrela montana and Heliocarpus americanus that had trapped mycorrhizal fungi from forest humus in the nursery to inoculate C. montana and H. americanus with native arbuscular mycorrhizal fungi. Inoculation with either a mixture of mycorrhizal roots from the four species or only with mycorrhizal roots from the same tree species were compared with effects of moderate fertilization. Assessment of plant growth and mycorrhizal status of 6-months-old Cedrela montana and Heliocarpus americanus revealed an improvement in growth and diverse associated fungi through mycorrhizal root inoculation in comparison with moderate fertilization. Moderate fertilization did not suppress mycorrhization.     

东方山羊豆GoGID基因表达载体构建及紫花苜蓿转化

根据已经克隆得到的东方山羊豆赤霉素受体(GoGID)基因,扩增编码区cDNA.以pBI121为基础载体,采用酶切连接法,构建植物超表达载体pBI121-GoGID.酶切鉴定表明:目的基因已经正确插入载体中,超表达载体构建成功.采用CaCl₂冻融法将重组载体转入农杆菌菌株中.以叶片为外植体,采用农杆菌介导的愈伤组织培养法,转化紫花苜蓿(Medicage sativa),得到抗性苗.对载体携带的nptⅡ基因、GUS基因进行PCR检测均成阳性,表明目的基因已成功导入紫花苜蓿基因组中.同时对转基因植株进行Southern-blot及RT-PCR检测,并均得到目的条带.本研究为进一步分析GoGID基因对紫花苜蓿生物量影响奠定了基础.     

Dipolar antiferromagnetism and quantum criticality in LiErF₄

Magnetism has been predicted to occur in systems in which dipolar interactions dominate exchange. We present neutron scattering, specific heat, and magnetic susceptibility data for LiErF(4), establishing it as a model dipolar-coupled antiferromagnet with planar spin-anisotropy and a quantum phase transition in applied field H(c|| = 4.0 ± 0.1 kilo-oersteds. We discovered non-mean-field critical scaling for the classical phase transition at the antiferromagnetic transition temperature that is consistent with the two-dimensional XY/h(4) universality class; in accord with this, the quantum phase transition at H(c) exhibits three-dimensional classical behavior. The effective dimensional reduction may be a consequence of the intrinsic frustrated nature of the dipolar interaction, which strengthens the role of fluctuations.     

Predictive thresholds for plague in Kazakhstan

In Kazakhstan and elsewhere in central Asia, the bacterium Yersinia pestis circulates in natural populations of gerbils, which are the source of human cases of bubonic plague. Our analysis of field data collected between 1955 and 1996 shows that plague invades, fades out, and reinvades in response to fluctuations in the abundance of its main reservoir host, the great gerbil (Rhombomys opimus). This is a rare empirical example of the two types of abundance thresholds for infectious disease-invasion and persistence- operating in a single wildlife population. We parameterized predictive models that should reduce the costs of plague surveillance in central Asia and thereby encourage its continuance.     

Dynamic oxygen mapping in the root zone by fluorescence dye imaging combined with neutron radiography

Purpose  

The rooted zone of a soil, more precisely the rhizosphere, is a very dynamic system. Some of the key processes are water uptake and root respiration. We have developed a novel method for measuring the real-time distribution of water and oxygen concentration in the rhizosphere as a biogeochemical interface in soil. This enables understanding where and when roots are active in respect to root respiration and water uptake and how the soil responds to it.