转无毒基因马铃薯抗晚疫病的研究

晚疫病菌(Phytophthora infestans)引起的马铃薯晚疫病是危害全球马铃薯生产的严重病害.通过基因工程方法把外源基因导入植物体内以增强抗病性被证明是一条行之有效的途径.应用植物基因工程技术将具有能激活植物自身防御系统的无毒基因与适合于植物背景、非专一性的病原物诱导启动子组合成嵌合基因构建到植物表达载体中.通过农杆菌或基因枪的介导转化植物,可筛选出高效广谱的抗真菌和细菌病害的转基因植株.本研究从病原细菌Pseudomonas syringae PV.tomato中获得的无毒基因avrD(0*93kb)和从病原真菌Phytophthora parasitica中获得的无毒基因Elicitin(0.294kb)分别与非专一性病原物诱导启动子Pill和BG组成含2个嵌合基因(Pill-avrD,BG-Elicitin)的植物表达载体pYH144和pYHEt.通过农杆菌LBA4404介导转化马铃薯,其中用pYH144载体转化2个品种(克新1号,2号),用pYHEt载体转化3个品种(Desiree,克新2号,4号),通过组织培养分别获得潮霉素(HygromycinB)标记的转基因马铃薯试管苗.将转基因试管苗扩繁,应用马铃薯脱毒微型种薯生产技术获得转无毒基因微型薯,在温室(15～25℃和湿度高)条件下,观察转无毒基因马铃薯植株中对晚疫病菌自然感染的抗性.1998年和1999年(每年的3-5月)的温室试验初步表明用avrD和elicitin基因分别转化的转无毒基因马铃薯植株都具有较明显的对晚疫病菌侵染的抗性,大部分转基因植株不表现或表现轻微的感病症状,对照植株(未转化)则表现明显的感病症状.转基因植株生长正常,且在感染后期(恢复期)生长良好.对照植株在恢复期生长弱和缓慢.在获得较多数量的转无毒基因马铃薯微型种薯的时候,将进行人工接种晚疫病菌和田间种植试验,从中筛选出抗真菌病和细菌病的转基因马铃薯株系.     

牛肉变质过程中微生物区系变化研究

微生物是引起牛肉变质的主要因素。未包装肉在 4℃条件下冷藏 7d后变质 ,表面带菌量达 3.3× 10 8个·cm-2 ,内部为 6 .8× 10 7个·g-1。保藏过程中微生物区系变化表现为革兰氏阴性杆菌上升 ,革兰氏阳性球菌下降 ,革兰氏阳性杆菌基本不变 ,变质时菌系变得简单。普通真空包装在 4℃条件下保存 3周后带菌量内外分别为 1.7× 10 7个·cm-2 和 1.8× 10 7个·g-1。在保藏过程中革兰氏阳性杆菌比例上升 ,革兰氏阴性杆菌上升不显著 ,革兰氏阳性球菌比例下降     

辣椒育苗基质配方施肥的研究

采用３因素２次通用旋转组合设计法，研究辣椒育苗基质的配方施肥技术，建立了配方配方优化模型，并计算出适合于重庆地区辣椒育苗基质的施肥方案。即尿素０．８８ｋｇ／ｍ＾３，过磷酸钙２０ｋｇ／ｍ＾３和不施钾肥。     

苎麻叶饲用效果及苎麻叶配制浓缩饲料的研究

苎麻叶按干物质计算含蛋白质在20%以上,可作各类畜禽的饲料,用鲜、干苎麻叶进行兔、鸡、猪的饲养试验表明,用鲜叶喂肉兔,其增重效果和饲料报酬优于牛皮菜和蕹菜;用占日粮4%和8%以上的苎麻叶干粉饲喂肉鸡和蛋鸡,对增重、性成熟和产蛋等均无不良影响;生长肥育猪的日粮中加入15%的苎麻叶粉,平均日增重和饲料消耗与对照组相近,用苎麻叶粉配制浓缩饲料喂生长肥育猪,平均日增重可达617～626 g,材肉比为3.27:1和3.48:1,优于普通配合饲料。     

固定在颗粒活性炭中的TiO_2光催化降解阿特拉津

利用30W低压汞灯作光源,采用固定颗粒活性炭中的TiO2(TiO2/GAC)作光催化剂,在浅盘反应器中考察了阿特拉津溶液的光催化降解。结果表明,在平均光强为4.38mW·cm-2,光催化剂投加量为7.0g·L-1,阿特拉津初始浓度为21.9mg·L-1,3wt%H2O2用量为30μL·15mL-1,投加方式为1次·2h-1,光照时间为6～10h时,去除率可达92.7%～94.7%,TOC去除率可达67.1%～78.3%。光催化剂增至10g·L-1,H2O2用量一次性加60μL,光照时间为3～4h时,去除率可达91.6%～93.7%,TOC去除率可达65.9%～73.9%。通过组合实验和紫外光谱图分析,估计了体系中影响去除率的光催化、吸附、光降解、H2O2的作用性质和大小,并估计了降解途径,认为同时存在侧链脱烷基反应和OH取代Cl的反应,在有H2O2存在时,使前反应较强。TOC值测定表明阿特拉津已从8个碳降至含2～3个碳的物质。     

铁岭地区稻瘟病近年发生动态分析

1993-2000年，在铁岭地区3个县区的生产田和试验田中的72个品种（系）上，采集了98份1000余个稻瘟病标样；采用单孢分离法分离应用有效单孢菌株52个；经中国7个鉴别品种上鉴定，52个单孢菌株划分为7群15个生理小种，填补了铁岭地区稻瘟病菌生理小种鉴定的空白。铁岭地区稻瘟病菌优势种群为ZD群，ZE群和ZF群；采用室内苗期和田间成株期结合的鉴定方式，鉴定铁岭地区水稻品种（系）35个；其中表现较为抗病的材料有：铁8711，开原7号，铁188，开9725，铁8958，开9909等。     

Isotopic evidence for massive oxidation of organic matter following the great oxidation event

The stable isotope record of marine carbon indicates that the Proterozoic Eon began and ended with extreme fluctuations in the carbon cycle. In both the Paleoproterozoic [2500 to 1600 million years ago (Ma)] and Neoproterozoic (1000 to 542 Ma), extended intervals of anomalously high carbon isotope ratios (δ(13)C) indicate high rates of organic matter burial and release of oxygen to the atmosphere; in the Neoproterozoic, the high δ(13)C interval was punctuated by abrupt swings to low δ(13)C, indicating massive oxidation of organic matter. We report a Paleoproterozoic negative δ(13)C excursion that is similar in magnitude and apparent duration to the Neoproterozoic anomaly. This Shunga-Francevillian anomaly may reflect intense oxidative weathering of rocks as the result of the initial establishment of an oxygen-rich atmosphere.     

Role for the membrane receptor guanylyl cyclase-C in attention deficiency and hyperactive behavior

Midbrain dopamine neurons regulate many important behavioral processes, and their dysfunctions are associated with several human neuropsychiatric disorders such as attention deficit hyperactivity disorder (ADHD) and schizophrenia. Here, we report that these neurons in mice selectively express guanylyl cyclase-C (GC-C), a membrane receptor previously thought to be expressed mainly in the intestine. GC-C activation potentiates the excitatory responses mediated by glutamate and acetylcholine receptors via the activity of guanosine 3',5'-monophosphate-dependent protein kinase (PKG). Mice in which GC-C has been knocked out exhibit hyperactivity and attention deficits. Moreover, their behavioral phenotypes are reversed by ADHD therapeutics and a PKG activator. These results indicate important behavioral and physiological functions for the GC-C/PKG signaling pathway within the brain and suggest new therapeutic targets for neuropsychiatric disorders related to the malfunctions of midbrain dopamine neurons.     

The three-dimensional structure of canine parvovirus and its functional implications

The three-dimensional atomic structure of a single-stranded DNA virus has been determined. Infectious virions of canine parvovirus contain 60 protein subunits that are predominantly VP-2. The central structural motif of VP-2 has the same topology (an eight-stranded antiparallel beta barrel) as has been found in many other icosahedral viruses but represents only about one-third of the capsid protein. There is a 22 angstrom (A) long protrusion on the threefold axes, a 15 A deep canyon circulating about each of the five cylindrical structures at the fivefold axes, and a 15 A deep depression at the twofold axes. By analogy with rhinoviruses, the canyon may be the site of receptor attachment. Residues related to the antigenic properties of the virus are found on the threefold protrusions. Some of the amino termini of VP-2 run to the exterior in full but not empty virions, which is consistent with the observation that some VP-2 polypeptides in full particles can be cleaved by trypsin. Eleven nucleotides are seen in each of 60 symmetry-related pockets on the interior surface of the capsid and together account for 13 percent of the genome.     

铁锰结核的元素组成及微形态特征

本文研究了钙质变性土中铁锰结核的矿质全量组成、微量元素丰度，微形态特征以及土壤和铁锰结核中各形态铁锰氧化物的组成特点，结果表明，铁锰结核中仍以ＳｉＯ２含量最高，但Ｆｅ２Ｏ３含量增加超过了Ａｌ２Ｏ３、ＭｎＯ含量大大超过了Ｋ２Ｏ、Ｎａ２Ｏ、ＴｉＯ２和ＭｇＯ的含量，所测定的９种微量元素中以Ｂａ含量最高，其次是Ｖ、Ｎｉ、Ｃｏ３种铁族元素，Ｃｕ和Ｐｂ含量也较高，但Ｚｎ和Ｃｒ含量较低，一般黑土层中的结核较小，