复合农药胁迫下黑土土壤微生物生态过程及分子生态学研究

利用传统及分子微生物生态学研究方法，研究了在乙草胺、甲胺磷、铜离子及二元组合胁迫下，黑土中六种类群微生物数量，细菌种群多样性，微生物碳源代谢（BloLoGGN）功能多样性及特征、土壤脱氢酶活性（DHA）、底物诱导呼吸强度（SIR）等土壤微生物特性的生态过程及变化规律。结果表明：所有农药处理，均对细菌、放线菌及磷细菌产生明显急性毒性效应；对土壤自生固氮菌及硅酸盐细菌生长产生长期的慢性毒性效应；对土壤真菌产生强烈的刺激效应，使土壤真菌数量显著升高。由165 ONA-PCR-DGGE方法对土壤细菌研究结果显示，所有农药胁迫均使土壤细菌多样度降低、细菌种群结构受到严重影响；土壤微生物群落代谢功能多样性及指纹特征因农药种类，浓度及组合不同，受到不同程度影响，功能多样性降低，代谢指纹特征被改变：所有农药组合处理均使土壤DHA受到长期抑制，对土壤底物诱导呼吸强度无显著影响，但改变了土壤DHA和S工R的动态变化规律。野外农药长期作用使土壤SIR与对照无显著差异，土壤DHA明显降低，土壤细菌、磷细菌、固氮菌及硅酸盐细菌数量明显减少，土壤真菌数量显著升高。由农药及其组合处理与土壤微生物群落生长剂量一效应关系，证明：三种农药对土壤微生物群落生长随投加农药种类、浓度和组合不同起促进或抑制双重作用；组合使相应单因子农药毒性增强，表现出协同或加和毒性效应；从清洁土壤中筛选出一株乙草胺耐受菌产酸克雷伯氏菌（Klebbsirlla oxytoca），在固体平板培养基上能耐受300omg·L-1乙草胺。

乙草胺、甲胺磷及其复合对黑土真菌的生态效应

农药对土壤微生物区系结构和功能的影响以及潜在的生态风险成为人们关注的热点之一。本文以中科院海伦生态站农田黑土作为实验土壤，采用室内模拟的方法，利用传统的（CFU和ergosterol）及分子微生物生态学技术（DGGE，real-time PcR，clolle library）研究了乙草胺、甲胺磷及其复合对黑土真菌的生态效应，并得出以下结果：经8周处理，中、高浓度乙草胺（150和250mgkg-1）对土壤真菌数量、生物量和可培养真菌种群多样性具有长期抑制效应。乙草胺处理8周后可培养真菌和土壤固氮微生物n州基因的种群结构不能得到恢复，而总的真菌结构可基本恢复。甲胺磷对土壤可培养真菌数量和生物量具有促进作用，以高浓度（250mgkg~(-1)）尤为显著。高浓度甲胺磷（25omgkg~(-1)）对nifH基因多样性有长期抑制效应。甲胺磷处理8周后可培养真菌种群结构不可恢复，而总的真菌和n积基因种群结构可部分恢复。两者复合后对真菌数量，生物量，多样性及n担基因多样性的影响无论是促进还是抑制其作用强度都大于单因子。处理8周后可培养真菌、总的真菌和n州基因三者的种群结构均不可恢复。克隆测序分析发现乙草胺、甲胺磷及其复合可明显促进植物致病真菌（colletolrichum；truncatum，Rhizoctonia zeae，Fusarium oxysporum）的生长，同时使土壤中常见的青霉菌数量减少，使农药处理后具有潜在的植物病害爆发的风险。本试验结果表明，乙草胺、甲胺磷及其复合对土壤真菌数量、结构、多样性和功能基因nifH的多样性及其种群组成有不同程度的影响，甚至产生某些不可逆的长期生态效应。复合处理对土壤真菌的影响要大于两个单因子作用，表现了明显的复合生态效应。一般来说受到午扰的真菌种群结构不容易自然恢复，因此建议在施用这两种农药过程中要避免大量、频繁的单独或复合施用。

青藏高原东缘青杨（Populus cathayana Rehd.）遗传多样性研究

青杨（Populus cathayana Rehd.）是青杨派杨树的主要树种之一，为我国特有乡土树种，其主要分布区之一是我国的青藏高原，集中分布地带在甘肃省中部及青海省东部，四川省西北部岷江上游和松潘等地区。本研究以青藏高原东缘青杨天然分布区的6个群体143个个体为材料，用AFLP、SSR和叶绿体SSR分子标记分析青杨天然群体的遗传多样性，分析其遗传结构和分化，比较6个群体间遗传多样性的高低和群体间的遗传关系。旨在为青杨基因资源评价、保护与保存、遗传改良策略制定等提供科学理论依据。通过以上研究，得出如下主要研究结果： 1 AFLP分子标记研究结果 采用4对选择性引物对6个青杨天然群体143个个体进行分析，扩增谱带分析共检测到175个位点，其中173个位点表现为多态，多态位点百分率高达98.9%。从整体上表现出较高的遗传多样性，Nei’s基因多样度(h)水平为0.306。从青杨天然群体位点分布来看，有高达20%的位点（32位点）为群体所特有，仅有9.14%的位点（16位点）在所有群体中存在。群体间的遗传分化极大，所有遗传变异中，有48.9%的遗传变异存在于群体间。在个体群丛（Individuals cluster）和主坐标（PCO analysis）分析中，青杨各群体未呈现任何地理模式，Mantel检测也显示各群体间遗传距离与地理距离无明显相关。研究认为，由于地理和空间上大尺度的隔离和地形地貌复杂使得群体间无法进行基因交流，导致群体间遗传分化极大，另外各群体在不同的选择压力下，经历各自独立的进化历程，这些都可能导致群体间遗传距离与地理距离的不相关。 2 SSR分子标记研究结果 在SSR分析中，7个位点在6个青杨天然群体143个个体中共检测到79个等位基因，每位点检测到的等位基因数在5-16之间，平均11.3个，总体上多态位点百分率达100%。平均观察杂合度和期望杂合度分别为0.792和0.802。Hardy-Weinberg平衡检验表明青杨大部分群体都处于非平衡状态，群体大部分位点都是偏离哈迪-温伯格平衡（76.3%），只有23.7%的测验满足哈迪-温伯格平衡。分析青杨天然群体内和群体间的遗传变异，基因分化系数（GST）为0.373，即有62.7%的遗传变异存在群体内，37.3%的遗传变异存在群体间。群体内的遗传变异高于群体间水平。根据各群体遗传距离UPGMA聚类分析，有来自相临分布区、近似气候类型的群体聚在一起的趋势，但Mantel检测反映遗传距离与地理距离间并无明显相关性。 3 cpSSR分子标记研究结果 分析来自青藏高原东缘6个青杨天然群体，所用cpSSR引物中有5对cpSSR引物（CCMP2、CCMP5、SCUO01、SCU03、SCU07）都表现较高的多态性，单个引物检测的片段数都在4以上。5对cpSSR引物共检测片段数26个，组成了12种叶绿体DNA单倍型。各群体的单倍型分布和频率有较大差异，群体单倍型多样性范围为0-0.4926，TS、JZ、PW和SHY群体单倍型多样性高于QHY和LED群体水平。本研究发现，分布在青藏高原东缘的青杨天然群体，群体间不存在共享的单倍型，各群体间存在极大的遗传分化（GST=0.9223）。从青藏高原东缘地区经历的地质历史事件来看，第四纪的冰期气候变迁可能是造成青杨现今遗传结构模式的主要因素之一。根据单倍型在各群体的分布情况，进行青杨群体聚类分析结果，各群体无明显的分组现象，青杨各群体也未呈现任何清晰地理模式。 由于不同分子标记在对群体遗传多样性检测能力与效率上存在差异，所以三种标记检测的青藏高原东缘青杨天然群体遗传多性水平也不尽一致，但在与用同种方法检测其它物种或同一物种不同种源群体比较，三种分子标记方法都揭示了青藏高原东缘青杨天然群体具有中等偏上的遗传多样性水平。结果分析表明，群体间遗传分化极大，这是由于青杨天然群体分布于青藏高原东缘，既有高原又有高山峡谷，由于地理和空间上大尺度的隔离和地形地貌复杂导致了基因流物理上的阻隔。三种分子标记研究结果经Mantel分析检测，遗传距离与地理距离之间都无明显相关性。较为一致的解释是，青杨分布区域地理和空间上大尺度的隔离和和地形地貌复杂导致群体之间不存在均匀扩散现象，另外各群体在不同的选择压力下，经历各自独立的进化历程，这些都可能导致群体间遗传距离与地理距离的不相关。 The wide geographical and climatic distribution of P. cathayana Rehd. indicates that there is a large amount of genetic diversity available, which can be exploited for conservation, breeding programs and afforestation schemes. The results are as follows: 1 Research results of AFLP genetic diversity In present study, genetic diversity was evaluated in the natural populations of P. cathayana originating from southern and eastern edge of the Qinghai-Tibetan Plateau of China by means of AFLP markers. For four primer combinations, a total of 175 bands were obtained, of which 173 (98.9%) were polymorphic. Six natural populations of P. cathayana possessed different levels of genetic diversity, high level of genetic differentiation existed among populations (GST=0.489) of P. cathayana. Individuals cluster and PCO analysis based on Jaccard’s similarity coefficient also showed evident population genetic structure with high level population genetic differentiation. The long evolutionary process coupled with genetic drift within populations, rather than contemporary gene flow, are the major forces shaping genetic structure of P. cathayana populations. Moreover, there is no correspondence between geographical and genetic distances in the populations of P. cathayana, seldom gene exchange among populations and different selection pressures may be the causes. Our finding of different levels of genetic diversity within population and high level of genetic differentiation among populations provided promising condition for further breeding or conservation programs. 2 Research results of SSR genetic diversity In this study, the genetic diversity of P. cathayana was investigated using microsatellite markers. In a total of 150 individuals collected from six natural populations in the southeastern part of the Qinghai-Tibetan Plateau in China, a high level of microsatellite polymorphism was detected. At the seven investigated microsatellite loci, the number of alleles per locus ranged from 5 to 16, with a mean of 11.3, the observed heterozygosities across populations ranged from 0.408 to 0.986, with a mean of 0.792, and the expected heterozygosities across populations ranged from 0.511 to 0.891, with a mean of 0.802. The proportion of genetic differentiation among populations accounted for 37.3% of the whole genetic diversity. The presence of such a high level of genetic diversity could be attributed to the features of the species and the habitats where the sampled populations occur: The southeastern part of the Qinghai-Tibetan Plateau is regarded as the natural distribution and variation center of the genus Populus in China. Variation in environmental conditions and selection pressures in different populations, and topographic dispersal barriers could be factors associated with the high level of genetic differentiation found among populations. The populations possessed significant heterozygosity excesses, which may be due to extensive population mixing at the local scale. The cluster analysis showed that the populations are not strictly grouped according to their geographic distances but the habitat characteristics also influence the divergence pattern. In addition, we suggest that population SHY should be regarded as an ecologically divergent species of P. cathayana. 3 Research results of cpSSR genetic diversity Genetic diversity of six natural populations of P. cathayana originating from the southeastern part of the Qinghai-Tibetan Plateau in China was studied by use of cpSSR markers. Based on 5 pairs of polymorphic primers screened from 12 pairs of primers, twenty-six different length fragments and twelve different kinds of haplotypes were reduced in 143 samples. There were significant variant haplotypes among the populations．There were no shared haplotypes found among populations, analysis of molecular variance indicated that a high proportion of the total genetic variance was attributable to variations among populations (92.23%). The pattern of genetic structure which is associated with spatial separation, variation in environmental conditions and selection pressures in different populations, is also the result of geological historical factor. A molecular phylogenetic tree based on the 12 haplotypes showed that the populations are not strictly grouped according to their geographic distances.

川西青杨组(Section Tacamahaca Spach)不同种的亲缘关系分析

青杨组（Section Tacamahaca Spach）杨树是我国重要的乡土经济树种，目前对其分子遗传变异和系统进化的研究还很少，尤其是在青杨组杨树遗传资源极为丰富的川西地区，杨树的分子进化及亲缘关系的研究极为缺乏，非常不利于该树种遗传资源的开发和利用。本研究从川西地区收集了青杨（Populus cathayana）、青海杨（P. prezewalskii）、滇杨（P. yunnanensis）、康定杨（P. kangdingensis）、西南杨（P. schneideri）、小叶杨（P.simonii）和三脉青杨（P. trinervis）这7 个青杨组树种的10 个群体，利用多种分子标记手段对其种间的亲缘关系进行比较，并结合形态和地史资料进行了全面的研究和评价，得到了如下的主要研究结果： 1. SSR 和ISSR 位点变异丰富。通过10 对引物对50 个杨树个体的DNA 样品进行了SSR 分析，所有位点展现了丰富的群体间和种间的多态性，多态位点率达到了100%，每位点的等位基因数变化范围为5 ~ 17，平均为11.9 个；通过11 条ISSR 随机引物对供试的混合DNA 样品进行分析，共检测到130 个标记，其中多态性标记为119 个，多态百分率为91.5%。研究认为，SSR 单个标记能展现高水平信息，而ISSR 单个引物能探测更多数量多态性。通过两个标记的遗传距离、聚类图和PCA 分析，表明：同一种内不同群体间的同源性最高；康定杨和西南杨有较近的亲缘关系；小叶杨和三脉青杨聚合在一起，显示了其相互较近的亲缘关系；滇杨与其它杨树种可能存在着较远的亲缘关系。 2. 采用4 对选择性引物对7 个青杨组杨树种10 个群体进行AFLP 分析，总共扩增出284 个位点，其中200 个位点显示出了多态性，多态位点百分比为70.4%，平均多态带为50 条。TE-AFLP 的分析总共扩增出192 个位点，其中139 个位点显示出了多态性，多态位点百分比为72.4%，平均多态带为34.7 条。比较的结果表明AFLP、TE-AFLP 的遗传信息含量比较接近，略小于ISSR，大约仅为SSR 的1/3；但这两个基于AFLP 的标记系统的信息探察能力也远大于ISSR 和SSR 标记系统。这两个分子标记的聚类结果，显示小叶杨、三脉青杨和滇杨三个种聚为一组，其中小叶杨与三脉青杨的亲缘关系更近；其它几个杨树种聚为一类，西南杨与青杨表现出较近的亲缘关系。 3. 所有7 对cpSSR 引物中，仅有4 个叶绿体位点在种间具有多态性，而在种内群体中并不具有多态性，共检测出13 个条带，组合成了4 种不同的单倍型；对于cpDNA的5 对引物，共检测出了73 条酶切片段，其中52 条是多态带，组合成了9 种不同的单倍型；而5 对mtDNA 通用引物未能检测出多态性的条带，表现出线粒体的保守性。叶绿体的聚类分析认为，小叶杨、三脉青杨和滇杨有较近的母性起源，且依次聚合；其余四种杨树聚为一类，并且康定杨与西南杨表现出最近的亲缘关系，并依次与青杨和青海杨聚合。 4. 根据本文的分子数据，结合形态和生境分布资料分析认为：青杨组杨树种内群体间的遗传变异程度是小于种间的遗传差异，显示了与传统分类一致的结果；三脉青杨和小叶杨有很近的亲缘关系，可能拥有相同的祖先类群；滇杨与小叶杨和三脉青杨之间具有一定的亲缘关系，特别是在其母性祖先的起源上有着一定的同源性；西南杨与青杨和康定杨均保持着较近的亲缘关系，且有可能是这两个种原始祖先杂交后所形成的。 Although western Sichuan is regarded as a natural distribution and variation center forthe Section Tacahamaca of the Populus species in China, little is currently known about themajority of poplar species occurring in this region. In the present study, molecular data wereutilized to determine the genetic relationships among Populus species in Section Tacamahacain western Sichuan including P. cathayana, P. prezewalskii, P. yunnanensis, P. kangdingensis,P. schneideri, P. simonii and P.trinervis. The results are as fellows: 1. The genetic variation at SSR and ISSR loci was abundant. All the 10 SSR loci werepolymorphic, and the number of alleles per locus varied from 5 to 17 with a mean valueequaling 11.9. Based on the 11 ISSR primers, 130 clear and reproducible DNA fragmentswere generated, of which 119 (91.5%) were polymorphic. Our results reveal that single SSRlocus can present more genetic information, while more polymorphic bands can be detectedby single ISSR primer. Moreover, the genetic distance, cluster and PCA analysisdemonstrated that: a close relationship among accessions of the same species and suggestedmonophyly in P. przewalskii and P. cathayana; P. schneideri is genetically highly similar to P.kangdingensis; P. trinervis and P. simonii have a close genetic affinity; P. yunnanensis isdistinct from the other species. 2. Genetic relationships of poplar species in Section Tacamahaca from western Sichuanwere evaluated by means of AFLP and TE-AFLP. For four AFLP primer combinations, atotal of 284 bands were obtained of which 200 (70.4%) were polymorphic with the average of50 polymorphic bands. For four TE-AFLP primer combinations, a total of 192 band wereobtained of which 139 (72.4%) were polymorphic with the average of 34.7 polymorphicbands. Our results indicate that the genetic information of AFLP is similar to that ofTE-AFLP, and little less than that of ISSR, but only about 1/3 of that of SSR. However, theability of information detection of the two AFLP-based markers is much higher than that ofISSR and SSR. In addition, the cluster analysis of AFLP, TE-AFLP and combined data revealthat: P. yunnanensis, P. trinervis and P. simonii clustered together, and P. trinervis and P.simonii showed more closed affinity; the other four poplar species clustered together, P.cathayana and P. schneideri showed more closed origin especially. 3. The cpSSR analysis for seven Populus species belonging to the Section Tacamahaca.Four out of the seven analyzed chloroplast loci were polymorphic, whereas none of the lociwere polymorphic across the accessions within a species. 13 bands and 4 different kinds ofhaplotypes were reduced. Based on 5 pairs of cpDNA primers, 73 fragments (52 polymorphic)and 9 kinds of haplotypes were produced. However, none of the polymorphic was detected bythe 5 mtDNA primer pairs, revealing conservation of mtDNA region. The cluster analysis ofcpDNA revealed that: similar maternal phylogeny among P. yunnanensis, P. trinervis and P.simonii; the other four species clustered together, P. schneideri and P. kangdingensis showedmore closed maternal lineage especially. 4. Our molecular data, morphological characters and nature habitat revealed that: sameto the traditional taxonomy assignment, genetic variation within a same Populus species islower than that among Populus species in Section Tacamahaca; P. yunnanensis may share itschloroplast ancestor with P. trinervis and P. simonii; moreover, sister genetic relationship of P.trinervis and P. simonii indicated their similar origin; P. schneideri clustered with P.kangdingensis and P. cathayana, respectively, and may have derived from an ancienthybridization event involving the ancestors of the two species.

卧龙自然保护区不同海拔的中国沙棘(Hippophae rhamnoides subsp. sinensis)天然群体的遗传多样性分析

中国沙棘是一种雌雄异株、风媒传粉的灌木或乔木，在中国西南的卧龙自然保护区有广泛的分布。本研究以采集于四川卧龙自然保护区5 个海拔(1800 m、2200 m、2600 m、3000 m、3400 m)梯度的中国沙棘天然群体为材料，以ISSR 和AFLP 标记技术研究其遗传多样性水平及其遗传结构，旨在了解卧龙地区中国沙棘天然群体的遗传多样性水平以及遗传多样性在群体间、群体内以及雌雄亚群体间的分布和特征，为中国沙棘树种的遗传改良及种质资源保存提供遗传研究背景与实验依据。同时探讨ISSR、AFLP 和RAPD三种标记对中国沙棘天然群体的遗传变异水平和群体间遗传结构的评估能力和各自的优缺点。研究得出以下主要结论： 1. ISSR和AFLP分析都表明卧龙自然保护区的中国沙棘群体拥有较高的遗传变异水平(h = 0.249，HT = 0.305)。出现这种结果的主要原因可能与卧龙自然保护区多变的气候条件和生境的异质度大有关。 2. ISSR 和AFLP 都揭示出卧龙自然保护区中国沙棘群体的遗传多样性随着海拔的增加发生显著的变化，表现为中海拔群体(2200 m 和2600 m)比高海拔群体(3000 m 和3400 m)和低海拔群体(1800 m)有更高的遗传多样性的趋势。出现这种趋势的可能解释是低海拔群体处在相对高温和相对干旱的环境，高海拔群体受到低温和紫外线胁迫，而中海拔群体存在中国沙棘生长的适宜环境。 3. ISSR 和AFLP 分析都表明：卧龙自然保护区中国沙棘的遗传结构遵循分布范围广、交配系统以异交为主的木本植物的通常模式，即大多数的遗传变异存在于群体内，只有少部分的遗传变异存在于群体间。 4. 经Mantel 检测表明，卧龙自然保护区中国沙棘群体间的海拔距离和对应遗传距离之间存在显著的正相关关系，即随着垂直海拔距离的增加，群体间的遗传距离也随之增加。Mantel 检测结果以及聚类分析将卧龙自然保护区5 个不同海拔的中国沙棘群体分为低、中、高海拔群体三组的研究结果都表明，海拔很可能是限制群体间基因交流的主要因素。 5. ISSR 分析发现同一海拔的雌雄亚群体首先聚类的研究结果表明，同一海拔的雌雄亚群体在遗传上最相似。方差分析结果表明只有3.8%的总遗传变异存在于雌雄亚群体间，这可能与雌雄植株间的交配和遗传物质的混合有关。 6. ISSR、AFLP 和RAPD 分析都表明卧龙自然保护区不同海拔的中国沙棘天然群体的遗传多样性水平较高。它们的分析结果估算得到的Nei's 平均基因多样度(h)分别为0.249、0.214 和0.170。从该结果可以看出ISSR 和AFLP 比RAPD 检测到更多的遗传多态性,这很可能是不同标记检测的基因组的位点不同所致。 7. 依据对不同标记系统的比较分析，认为ISSR、AFLP 和RAPD 三种分子标记系统都能成功地用于调查卧龙自然保护区不同海拔的中国沙棘群体的遗传变异水平及遗传变异结构，提供关于中国沙棘天然群体多态性水平和遗传变异分布的有用信息。在三者中，AFLP 具有最高效能指数和标记指数，在确定种间分类关系或鉴别个体方面是一种比较理想的标记。 Hippophae rhamnoides subsp. sinensis, a dioecious and deciduous shrub species,occupies a wide range of habitats in the Wolong Nature Reserve, Southwest China. Ourpresent study investigated the pattern of genetic variation and differentiation among fivenatural populations of H. rhamnoides subsp. sinensis, occurring along an altitudinal gradientthat varied from 1,800 to 3,400 m above sea level in the Wolong Natural Reserve, by usingISSR and AFLP markers to guide its genetic improvement and germplasm conservation. And,comparative study of ISSR, AFLP and RAPD was performed to detect their capacity toestimating the level and pattern of genetic variation occurring among the five elevationpopulations of H. rhamnoides subsp. sinensis, and to discuss their application to the study onplant genetics. The results were list following: 1. The ISSR and AFLP analysis conducted for the H. rhamnoides subsp. sinensispopulations located in the Wolong Natural Reserve of China revealed the presence of highlevels of genetic variation (h = 0.249, HT = 0.305). Besides such features as relatively widedistribution, dominantly outcrossing mating system, and effective seed dispersal by small animals and birds, it is sometimes argued that hard climatic conditions and heterogeneous habitats may also contribute to high levels of diversity. 2. Genetic diversity of H. rhamnoides subsp. sinensis populations was found to varysignificantly with changing elevation, showing a trend that mid-elevation populations (2,200m and 2,600 m) were genetically more diverse than both low-elevation (1,800 m) andhigh-elevation populations (3,000 m and 3,400 m). H. rhamnoides subsp. sinensis is thoughtto be stressed by drought and high temperature at low elevations, and by low temperature athigh elevations. The high genetic variability present in the mid-elevation populations of H.rhamnoides subsp. sinensis is assumed to be related to a greater plant density in the middlealtitudinal zone, where favorable ecological conditions permit its continuous distributioncovering the zone from 2,200 m to 2,600 m above sea level. 3. The genetic structure of H. rhamnoides subsp. sinensis revealed by ISSRs andAFLPs followed the general pattern detected in woody species with widespread distributionsand outcrossing mating systems. Such plants possess more genetic diversity withinpopulations and less variation among populations than species with other combinations oftraits. 4. In the present study, Mantel tests showed positive correlations between altitudinaldistances and genetic distances among populations or subpopulations. The observedrelationship between altitude and genetic distances, and the result of the cluster analysisincluding populations or male subpopulations and classifying the groups into three altitudeclusters suggest that altitude is a major factor that restricts gene flow between populationsand subpopulations. 5. The analysis of molecular variance showed that only 3.8% of the variability residedbetween female and male subpopulations. Such a very restricted proportion of the totalmolecular variance between female and male subpopulations is due to common sexuality andmixing of genetic material between females and males. 6. The analysis based on ISSRs, AFLPs and RAPDs all revealed relatively high levelsof genetic variation among different altitudinal populations of H. rhamnoides subsp. sinensisin Wolong Natural Reserve of China. Their estimates of mean Nei’s gene diversity is equal to0.249, 0.214 and 0.170 respectively, suggesting the higher capacity of detecting geneticvariation of ISSR and AFLP than RAPD. It might be ascribed to their distinct sensitivity todifferent type of genetic variation. 7. Based on the coparative study on ISSR, AFLP and RAPD, we drew a conclusion thatthey all successfully reveal some useful information concerning the level and pattern ofgenetic vatiation occurring among different elevation populations of H. rhamnoides subsp.sinensis. AFLP is a ideal tool to taxonomic study and individual identification for theirhighest efficiency index and marker index among the three marker systems.

小麦胚乳蛋白组分和Glu-B3位点基因核心编码区差异与小麦品质关系的研究

小麦加工品质改良已成为我国小麦育种的主要目标之一。特别是我国加入WTO以后，对小麦产品的质量提出了更高的要求，小麦品质改良的任务将更加艰巨和重要，小麦胚乳蛋白是影响小麦加工品质性状的重要因素。因此，深入了解小麦胚乳蛋白对加工品质性状的影响及其分子基础，为品质改良提供理论依据和科学指导，对加速我国小麦品质育种和优质小麦生产具有重要意义。本研究选用在麦谷蛋白5个基因位点(Glu-A1、Glu-B1、Glu-D1、Glu-B3和Glu-D3)上均含不同等位基因的小麦品种99G45和京771及Pm97034和京771杂交F9代共164个麦谷蛋白纯合系，及228个中国推广普通小麦品种和高代育成品系为试材，研究了麦谷蛋白Glu-1和Glu-3位点基因等位变异对籽粒蛋白、湿面筋含量、Zeleny沉降值和SDS沉降值间的关系；本研究还利用小麦A、B和D基因组中低分子量麦谷蛋白亚基（LMW-GS）基因特异引物，通过PCR方法克隆了1个Glu-A3位点和3个Glu-B3位点LMW-GS基因片段，在此基础上分析了不同等位基因对品质造成差异的分子基础；另外，本研究对中国近年推广的部分品种和育成的高代品系资源的多样性进行了分析。现将主要研究结果简述如下： 1. 对来自三个麦区的148份材料的醇溶蛋白组成进行了分析，结果表明，各麦区醇溶蛋白模式具有较大差异。在ω区,A7、B、E、F、G、J、P、Q、S和U仅存在于西南秋播麦区；A3、M、N、R、W和X仅存在于黄淮特种麦区；K仅存在于北方冬麦区；A6是北方冬麦区出现频率最高的带型模式，而西南秋播麦区中D出现的频率最高。ω-区的E、H和M几种模式是以前国内外未曾报道的。且初步确定，这些模式对品质性状具有正效应。至于γ区,A、B、D、E和F在各区均有出现，其中B和E在各区出现的频率都很高，在26.1-39.6％之间。相反，H 仅出现在黄淮特种麦区，J仅限于西南秋播麦区。对于β-区醇溶蛋白，B型模式在所有区中都相当高，而模式A仅存在于第三区.对于α-区，模式A在Ⅲ区而模式D在Ⅱ区出现的频率很高。1BL.1RS易位系在中国小麦品种中出现频率高达41.2％，在I, II和Ⅲ麦区的出现频率分别为 45.5、43.5和35.2%。各生态区模式的差异可能是品种适应不同生态条件和人为选择的结果，但这有待进一步证明。由于醇溶蛋白位点（Gli-1）与LMW-GS位点（Glu-3）紧密连锁，本结果可为下面确定普通小麦LMW-GS等位基因变异所用。 2. 利用Gli-1与Glu-3的紧密连锁，以228个小麦品种/系为材料，首次对中国小麦品种麦谷蛋白亚基的6个位点进行综合分析，研究小麦籽粒蛋白与品质性状间的关系，结果表明6个高分子量（HMW）和低分子量（LMW）麦谷蛋白位点对蛋白质含量的效应大小为，Glu-D1>Glu-B3>Glu-A1=Glu-B1> Glu-A3=Glu-D3；对GMP含量的效应大小为, Glu-A3>Glu-B3>Glu-D1> Glu-B1>Glu-A1>Glu-D3；对湿面筋含量的效应大小为, Glu-B1>Glu-B3= Glu-D3>Glu-A3>Glu-A1>Glu-D1；对Zeleny沉降值的效应大小为, Glu-A1> Glu-B3>Glu-D3>Glu-D1>Glu-B1>Glu-A3；对SDS沉降值的效应大小为, Glu-B3>Glu-A1=Glu-D1=Glu-A3>Glu-D3>Glu-B1。对蛋白含量而言，各位点的最佳组合方式为1、17+18、5+10、Glu-A3e、Glu-B3g、Glu-D3b；对湿面筋含量而言，各位点的最佳组合方式为1、6+8、5+10、Glu-A3d、Glu-B3c、Glu-D3b；对Zeleny沉降值而言，各位点的最佳组合方式为N、17+18、5+10、Glu-A3d、Glu-B3d、Glu-D3b；对SDS沉降值而言，各位点的最佳组合方式为1、7+8、2.2+12、Glu-A3b、Glu-B3g、Glu-D3b。另外，分析了稀有亚基对5+12与2.2+12与品质性状的关系，认为5+12对品质有负效应，2.2+12对品质有正效应。在品质育种时，应对优异组合或优异亚基加以利用。 3. 首次利用重组自交系（RILs）为材料，研究麦谷蛋白亚基表达量与品质性状的关系，通过对重组自交系中各HMW-GS表达量的分析，认为，就单个亚基的表达量而言，7亚基最高；其次为2亚基、5亚基、12亚基和10亚基；亚基9和1的表达量最小；N亚基不表达。对成对出现的亚基对而言，x型和y型亚基的总表达量2+12>5+10>7+9>17+18。就单个亚基与品质性状的关系而言，仅有10亚基的表达量与蛋白含量的相关性达5%的显著水平，2亚基的表达量与湿面筋含量呈负相关，显著水平也达5%，其余单个亚基对品质性状均无显著影响；就x型/y型亚基的比例来看，2/12和5/10对湿面筋含量都有显著的负效应；对某一位点等位基因控制的亚基表达总量来看，2+12对SDS沉降值有显著负效应。另外，本研究得出：2＋12的亚基对的负效应主要体现在2亚基上，且在同一位点上，x型亚基的表达量大于y型。所以推导稀有亚基组合2+10很可能也是劣质亚基。 4. 以 Glu-A1、Glu-B1、Glu-D1、Glu-B3和Glu-D3作为5个因素对99G45/京771和Pm97034/京771杂交后代的蛋白质含量和SDS沉降值进行多因素方差分析。结果表明，Glu-A1和Glu-D3对蛋白含量的加性效应达5％显著水平；Glu-D1 * Glu-D3对蛋白质含量的互作效应也达5%显著水平；其余位点的加性和互作效应对蛋白质含量的影响均不显著。对SDS 沉降值而言，Glu-D1的加性效应最大,贡献率为4.2 % ,达1 %显著水平,其次是Glu-B1位点,贡献率为3.3% ,达5%显著水平。其余位点对SDS 沉降值的加性和互作效应均未达5%显著水平。总体而言, 各位点对蛋白含量的效应大小为Glu-D3 > Glu-A1 > Glu-D1>Glu-B1>Glu-B3；对SDS沉降值的效应大小为Glu-D1>Glu-B1> Glu-D3>Glu-A1> Glu-B3。Glu-D1和Glu-D3位点上等位基因变异对蛋白含量有显著或极显著影响，含Glu-D1d和Glu-D3 GD、Glu-D3 JD基因的株系分别比含Glu-D1a和Glu-D3 PD基因的株系有较高的蛋白含量；在该遗传背景下，麦谷蛋白各基因位点对蛋白含量的效应大小依次排列为：Glu-A1位点1>N；Glu-B1位点7+9>17+18>14+15；Glu-D1位点5+10>2+12；Glu-B3位点GB>JB>PB；Glu-D3位点GB>JB>PB。对SDS沉降值的效应大小依次排列为：Glu-A1位点1>N；Glu-B1位点7+9=17+18>14+15；Glu-D1位点5+10>2+12；Glu-B3位点GB>JB>PB；Glu-D3位点GB>JB>PB。所以，对蛋白含量和SDS沉降值均较好的组合为1，7+9，5+10，GB，GD。 5. 因为GB和PB对品质的效应有显著差异，选取LMW-GS位点特异扩增引物对京771、99G45和Pm97034的Glu-B3位点进行扩增，结果得到三个不一样的扩增片段（Genebank号为DQ539657－DQ539659），得到的基因片段与Genebank中已报道的同类序列高度同源。通过克隆片段组成的分析，发现对Pm97034的序列较京771和99G45段少一个7氨基酸的重复单元，这可能是它较另外两个片段对面筋强度影响小的主要原因；另外，在99G45的序列中，124位处出现L（亮氨酸）代替P（脯氨酸），158位处出现了T（苏氨酸）代换M(蛋氨酸)，这可能是99G45Glu-B3位点序列对SDS沉降值的效应显著优于Pm97034的原因。 6．通过对RILs各位点同普通小麦品种（系）各位点与品质关系的比较，发现对SDS沉降值的效应，各位点在不同研究材料中是不同的，普通小麦中：Glu-B3>Glu-A1=Glu-D1=Glu-A3>Glu-D3>Glu-B1，RILs中：Glu-D1>Glu-B1> Glu-D3>Glu-A1> Glu-B3。利用重组自交系材料（完全排除了1BL/1RS易位干扰）所得到的结果与Gupta and MacRitchie (1994)所得结论一致。进一步证实了1BL/1RS易位对小麦品质的重要影响。对蛋白含量而言，普通小麦品种（系）中，Glu-D1>Glu-B3>Glu-A1=Glu-B1> Glu-A3=Glu-D3，RILs中，Glu-D3 > Glu-A1 > Glu-D1>Glu-B1>Glu-B3，和对SDS沉降值的效应一样，推断在非1BL/1RS易位的情况下，各位点对其效应应为Glu-D3 > Glu-A1 > Glu-D1>Glu-B1>Glu-B3。 对同一位点的等位基因而言，普通小麦和重组自交系中Glu-A1和Glu-D1上的等位基因对品质性状的贡献是一致的，但Glu-B1上的等位基因对SDS沉降值的贡献发生了变化，普通小麦中17+18>7+9，RILs中7+9>17+18，这可能也是1BL/1RS造成的。 Baking quality improved is one of the main object of wheat bread in China. The overall objective of the present studies was to increase the understanding about protein quality in wheat, i.e. to make it possible to improve the production of wheat with desired quality for different end-uses. With the analysis of gluten protein in RILs, 99G45/Jing 771 and Pm97034/Jing, and 228 wheat cultivars or lines in China, the correlations between glutenin compositions and protein content, glutenin macropolymer(GMP), wet gluten content, Zeleny sedimentation value and SDS sedimentation value contentand breadmaking quality were studied. Also a rapid and efficient detection method of geneticpolymorphism at Glu-B3 loci in wheat was established using polymerase chain reaction(PCR).The results obtained were as follows: 1. Cultivated Chinese wheat germplasm has been a valuable genetic resource in international plant breeding. Patterns of gliadin among cultivated Chinese accessions are unknown, despite the proven value and potential novelty. The objective of this work was to analyse the diversity within improved Chinese wheat germplasm. The electrophoretic banding patterns of gliadin in common wheat cultivars and advanced lines were determined by acid-polyacrylamide gel electrophoresis. For 148 leading commercial cultivars and promising advanced lines used in our study, 48 patterns were identified, 29 corresponding to ω-gliadin, 9 to γ-gliadin, 5 to β-gliadin and 5 to α-gliadin. The most frequent patterns were A6 in ω; B in γ; B in β and A in the region of α. 116 band types appeared in the148 samples: 94 accessions had unique gliadin types, and 22 gliadin types while not unique were found in 54 accessions. The gliadin patterns of Chinese wheat cultivars and lines greatly differed from the patterns of wheat lines from other countries. Three patterns, E, J, H, M, N and O in the ω-zone had not previously been reported. Three wheat zones，the Northern Winter Wheat Region, the Yellow and Huai Valley River valleys Winter Wheat Region and the Southwestern Winter Wheat Region，in China showed different frequencies in their gliadin patterns. This information can be used to monitor genetic diversity with Chinese wheat germplasm. 2. To analyse the relationship between the loci and characteristics quality, we utilized the 228 cultivars/lines. The results showed that : For protein content, Glu-D1 >Glu-B3>Glu-A1=Glu-B1>Glu-A3=Glu-D3. For GMP content, Glu-A3>Glu-B3 >Glu-D1>Glu-B1>Glu-A1>Glu-D3. For wet gluten content, Glu-B1>Glu-B3= Glu-D3>Glu-A3>Glu-A1>Glu-D1. For Zeleny sedimentation value, Glu-A1>Glu-B3> Glu-D3>Glu-D1>Glu-B1>Glu-A3, For SDS sedimentation value, Glu-B3>Glu-A1= Glu-D1= lu-A3>Glu-D3>Glu-B1。For protein content, the best combination of 6 loci is (1,17+18,5+10,Glu-A3e, Glu-B3g,Glu-D3b). For wet gluten content, the best combination of 6 loci is (1,6+8,5+10,Glu-A3d,Glu-B3c,Glu-D3b). For Zeleny sedimentation value, the best combination of 6 loci is (N,17+18,5+10,Glu-A3d, Glu-B3d, Glu-D3b). For SDS sedimentation value, the best combination of 6 loci is(7+8,2.2+12,Glu-A3b, Glu-B3g,Glu-D3b)。Additional, we analysed the relationship between the subunits 5+12 and 2.2+12, think that 5+12 was negative for quality, 2.2+12 is postive for quality. It should be effective utilized. 3. It’s the first time to utilize RILs to study the relationship between subunits expression quantity and characteristics quality. The results showed that: For single subunit, the expression quantity of 7 is the highest. Then the 2, 5, 12 and 10. The expression of subunit 9 and 1 is the lowest. Subunit N is not expressed. For subunits, the expression quantity of x type and y type are 2+12>5+10>7+9>17+18. The significant relation of 5% only showed between the expression quantity of subunit 10 and protein content. The relationship between expression quantity of others and characteristic quality was not significant. For x type/ytype, 2/12 and 5/10 is negative relation insignificant level. For the subunit(s) in a loci, Only 2+12 effect SDS sedimentation value negative in significant level. 4. With RILs 99G45/Jing 771 and Pm97034/Jing 771, we found that: The effective of Glu-A1, Glu-D3 and Glu-D1 * Glu-D3 for protein content is significant at 5% level. The effect of other loci for protein wre not significant. For SDS sedimentation value, the effect of Glu-D1is the highest, which contribution is 4.2 % .Then the Glu-B1, contribution is 3.3%. The effect of other loci for SDS sedimentationvalue were not significant. In total, for protein content: Glu-D3 > Glu-A1 > Glu-D1>Glu-B1>Glu-B3; for SDS sedimentationvalue: Glu-D1>Glu-B1> Glu-D3>Glu-A1>Glu-B3. The effect of alleles in Glu-D1 and Glu-D3 loci are significant at 1% or 5%. In Glu-A1, 1>N; Glu-B1, 7+9>17+18>14+15; Glu-D, 5+10>2+12; Glu-B3, GB>JB>PB; Glu-D3, GB>JB>PB. For SDS sedimentation, Glu-A1, 1>N; Glu-B1, 7+9=17+18>14+15; Glu-D1, 5+10>2+12; Glu-B3, GB>JB>PB; Glu-D3, GB>JB>PB. The best combinations for SDS sedimentation value is 1，7+9，5+10，GB，GD. 5. Because of the difference of GB and PB for SDS sedimentation value, we selected the specific primer for LMW-GS loci to amplified the Glu-B3 of Jing771, 99G45and Pm97034. We got 3 amplify fragment (Gene Bank accession number are DQ539657－DQ539659）. We found that the fragment of Pm97034 were deleted a repetitive 7 amino acid domain, which is perhaps the reason effect the gluten strength. Furthermore, in the position 124 of sequence 99G45, L has been replaced with P. Position 158, T replaced M, which may be the reason why the Glu-B3 locus of 99G45 is prefer to Pm97034 when refer to SDS sedimentation value. 6. Comparing the results of RILs and common wheat, we found that perhaps just the1BL/1RS made the difference of loci in different accession.

青藏高原青稞淀粉资源的评价

青稞（Hordeum vulgare L.var．nudum Hook．f.），即裸大麦，是兼食用、饲用和酿造于一体的作物，有着重要的利用价值。淀粉是青稞籽粒中含量最多、最重要的碳水化合物，淀粉含量、直支淀粉比将会直接影响淀粉的功能特性，进而影响淀粉的应用领域。我国青藏高原青稞的栽培和食用历史悠久，特色青稞资源极其丰富。目前关于青藏高原青稞淀粉特性的报道还不多见，筛选和培育特色淀粉青稞利于拓展青稞的应用领域, 从而提高其经济价值。 本研究以114份青藏高原青稞品种(系)为实验材料，通过SDS-PAGE对材料的胚乳淀粉颗粒结合蛋白（SGAPs）进行分离，确定各蛋白的分子量大小、组合类型和多态性等。然后按照国标法测试材料的籽粒总淀粉含量和直链淀粉含量，通过微型糊化粘度仪分析相应的淀粉糊化特性，最后使用显微镜观察比较了青稞的淀粉颗粒形态特征。主要结果如下： 1、114种青稞中共分离出20种不同的SGAP条带，条带分子量为35.00～112.39 KDa，分布频率为12.28～97.37%。材料含有的SGAPs条带数从10到14不等，超过一半的材料含11种SGAP条带。20种条带形成16种组合类型，其中西藏地区青稞包含所有16个组合类型，四川地区青稞包含其中12个组合类型。青藏高原青稞籽粒淀粉颗粒结合蛋白的差异很大，遗传多样性丰富。 2、114份青稞的总淀粉含量、直链淀粉含量、直支淀粉比、峰值粘度、糊化温度和峰值温度的变幅分别为51.26～66.70%、14.64～29.74%、0.17～0.42、194～1135BU、58.8～65.2℃和81.4～92.4℃，相应的平均值分别为59.82%、23.60%、0.31、722.30BU、62.1℃和88.8℃。群体在总淀粉含量、直链淀粉含量、直支淀粉比、峰值粘度、糊化温度和峰值温度上的分布具有明显的正态性；所有胚乳淀粉体的淀粉粒都呈复粒结构。对西藏和四川的材料进行了分组比较， 两地区的青稞在直链淀粉含量和直支淀粉比上的差异达到显著水平。 3、筛选出18份具有特殊淀粉特性的青稞品种，其中5份材料的总淀粉含量超过65%，包括NB63-1、NB67、甘孜白六棱、98221-1和NB63；3份材料的直链淀粉含量大于29%，包括藏青85、藏青3号和喜马拉6号；8份材料的直支淀粉比小于0.25，包括99033-6、春青稞、阿坝330、Jan-03、米麦114、396、NB63-1和92013；7份材料的糊化温度低于60℃，同时材料的峰值粘度大于1000BU,并且峰值温度低于90℃，包括足捉春、Jan-03、阿坝330、米麦114、春青稞、20003和阿青5号。 4、各淀粉特性间存在高度相关性。直链淀粉含量和直支淀粉比与糊化温度成极显著正相关，与峰值粘度成极显著负相关，与A型淀粉粒数量和大小呈负相关。不同SGAPs组合的品种之间，淀粉含量和淀粉糊化特性间差异均达显著水平。SGAP2、SGAP5、SGAP6和SGAP7可能对籽粒直链淀粉含量、直支淀粉比和糊化温度有正向效应；SGAP3、SGAP9∼SGAP20可能对峰值粘度有正向效应。 本研究对青藏高原青稞淀粉资源进行了较为全面的评价，对该区青稞淀粉特性有了系统的认识。研究筛选出的特殊青稞品种可作为青稞育种和青稞淀粉工业应用的潜在资源，淀粉特性差异巨大的众多青稞品种也为拓宽青稞应用领域提供了丰富的资源保障。本研究对部分SGAPs在性质上的鉴定和功能上的初步推断为青稞材料的筛选提供了指导，也为品质育种提供了理论参考。 Hulless barley (naked barley, Hordeum vulgare L.) is a short- season, early maturing crop with a wide range of adaptation. It has been attracting more and more attention due to its superior nutrition and extensive industrial applications. Starch is the main ingredient in hulless barley seeds which makes up 65 percent of hulless barley’s dry weight. The ratio of the amylose/amylopectin and the size, shape, distribution of starch granules can affect the physico-chemical and functional properties of starch, which may turn affect its utilizations. The Qinghai-Tibet Plateau, which is located in southwestern China, is a typical area of vertical agricultural ecosystem and one of the barley origin centers with abundant hulless barley resources. There are little reports about hulless barley in Qinghai-Tibet Plateau at present. To screen and cultivate some characteristic hulless barley can improve its value. An improved SDS-PAGE was used to identify SGAPs combination of 114 hulless barley varieties. Starch content (total starch and amylose starch) was determined according to the standard methods GB5006-85 and GB/T 15683 using PerkinElmer M341 Precision Automatic Polarimeter and UV spectrophotometer 755B respectively. The pasting properties were measured by BRABENDER Micrio Visco-Amylo- Graph 803201. The morphology of starch granules were observed and compared with Axioplan 2 Imaging light microscopy. The following were the results obtained: 1. There were 20 major SGAPs presented in 114 varieties, with the molecular weight ranged from 35.00 to 112.39 KDa, and the frequencies ranged from 12.28% to 97.37%. The number of SGAP bands in each accession varied from 10 to 14, more than half of the population had 11 bands. There were 16 distinct SGAP patterns in the 114 varieties, the Tibet hulless barley had all of the 16 types and the Sichuan hulless barley had 12 types. The results indicated the Qinghai-Tibet Plateau hulless barley had a polymorphism of the SGAPs. 2. The ranges of the total starch content, amylose content, Am/Ap, peak viscosity, pasting temperature and peak temperature of the 114 hulless barley were 51.26～66.70%,14.64～29.74%,0.17～0.42,194～1135BU,58.8～65.2 and 81.4℃～92.4, with an average of ℃59.82%, 23.60%, 0.31, 722.30BU, 62.1 and 88.8,℃℃ respectively. The distributions of the total starch content, amylose content, Am/Ap, peak viscosity, pasting temperature and peak temperature were visibly normal school. All of the amyloplasts in endosperm of varieties showed bimodal size distributions.The main starch properties of hulless barley from Tibet and Sichuan were separated and compared, the differences on amylose content and Am/Ap were obvious. 3. Eighteen accessions which had special starch properties were screened out. Five accessions with total starch content beyond 65%, including NB63-1, NB67, Ganzibailiuleng, 98221-1 and NB63; three accessions, Zangqing85, Zangqing3 and Ximala6, with the highest amylose content (>29%); five accessions with Am/Ap less than 0.25, including 99033-6, Chun Qingke, A Ba 330, Jan-03, Mi Mai114, 396, NB63-1 and 92013; seven accessions had a pasting temperature under 60, ℃meanwhile their peak viscosity beyond 1000BU and their peak temperature under 90℃，including Zu Cuochun, Jan-03, A Ba 330, Mi Mai 114, Chun Qingke, 20003 and A Qing 5. 4. There were high correlations between starch properties. Amylose content and Am/Ap were positively correlated to pasting temperature, negatively correlated to peak viscosity, negatively correlated to the number and granule size of A-type granule. Different SGAP combinations caused significant diversities in starch content and pasting properties. SGAP2, SGAP5, SGAP6 and SGAP7 may have positive effect on amylose content, Am/Ap and pasting temperature; SGAP3, SGAP9∼SGAP20 may have positive effect on peak viscosity. Our research made a comprehensive evaluation on the hulless barley starch from the Qinghai-Tibet Plateau, we can get a systemic understanding. Some special accessions were screened out can be used on the hulless barley breeding lines and industries utilization.The combination of the SGAPs may become a criterion to evaluate the hulless barley endosperm starch quality. Consequently, the results will be good information for further studies on the hulless barley.

Production of heavy and superheavy nuclei in massive fusion reactions

Within the framework of a dinuclear system (DNS) model, the evaporation-residue excitation functions and the quasi-fission mass yields in the 48Ca induced fusion reactions are investigated systematically and compared with available experimental data. Maximal production cross sections of superheavy nuclei based on stable actinide targets are obtained. Isotopic trends in the production of the superheavy elements Z = 110, 112–118 based on the actinide isotopic targets are analyzed systematically. Optimal evaporation channels and combinations as well as the corresponding excitation energies are proposed. The possible factors that influencing the isotopic dependence of the production cross sections are analyzed. The formation of the superheavy nuclei based on the isotopes U with different projectiles are also investigated and calculated.

Production of new superheavy Z=108-114 nuclei with U-238, Pu-244, and Cm-248,Cm-250 targets

Within the framework of the dinuclear system (DNS) model, production cross sections of new superheavy nuclei with charged numbers Z=108-114 are analyzed systematically. Possible combinations based on the actinide nuclides U-238, Pu-244, and Cm-248,Cm-250 with the optimal excitation energies and evaporation channels are pointed out to synthesize new isotopes that lie between the nuclides produced in the cold fusion reactions and the Ca-48-induced fusion reactions experimentally, which are feasible to be constructed experimentally. It is found that the production cross sections of superheavy nuclei decrease drastically with the charged numbers of compound nuclei. Larger mass asymmetries of the entrance channels enhance the cross sections in 2n-5n channels.

Neutron and proton diffusion in fusion reactions for the synthesis of superheavy nuclei

The restriction of the one dimensional (1D) master equation (ME) with the mass number of the projectile-like fragment as a variable is studied, and a two-dimensional (2D) master equation with the neutron and proton numbers as independent variables is set up, and solved numerically. Our study showed that the 2D ME can describe the fusion process well in all projectile-target combinations. Therefore the possible channels to synthesize super-heavy nuclei can be studied correctly in wider possibilities. The available condition for employing 1D ME is pointed out.

Separation of potential and kinetic electron emission from Si and W induced by multiply charged neon and argon ions

T he total secondary electron emission yields, gamma(T), induced by impact of the fast ions Neq+ (q = 2-8) and Arq+ (q = 3-12) on Si and Neq+ (q = 2-8) on W targets have been measured. It was observed that for a given impact energy, gamma(T) increases with the charge of projectile ion. By plotting gamma(T) as a function of the total potential energy of the respective ion, true kinetic and potential electron yields have been obtained. Potential electron yield was proportional to the total potential energy of the projectile ion. However, decrease in potential electron yield with increasing kinetic energy of Neq+ impact on Si and W was observed. This decrease in potential electron yield with kinetic energy of the ion was more pronounced for the projectile ions having higher charge states. Moreover, kinetic electron yield to energy-loss ratio for various ion-target combinations was calculated and results were in good agreement with semi-empirical model for kinetic electron emission.

Formation of superheavy nuclei in cold fusion reactions

Within the concept of the dinuclear system (DNS), a dynamical model is proposed for describing the formation of superheavy nuclei in complete fusion reactions by incorporating the coupling of the relative motion to the nucleon transfer process. The capture of two heavy colliding nuclei, the formation of the compound nucleus, and the de-excitation process are calculated by using an empirical coupled channel model, solving a master equation numerically and applying statistical theory, respectively. Evaporation residue excitation functions in cold fusion reactions are investigated systematically and compared with available experimental data. Maximal production cross sections of superheavy nuclei in cold fusion reactions with stable neutron-rich projectiles are obtained. Isotopic trends in the production of the superheavy elements Z=110, 112, 114, 116, 118, and 120 are analyzed systematically. Optimal combinations and the corresponding excitation energies are proposed.

Possible way to synthesize superheavy element Z=117

Within the framework of the dinuclear system model, the production of superheavy element Z = 117 in possible projectile-target combinations is analysed systematically. The calculated results show that the production cross sections are strongly dependent on the reaction systems. Optimal combinations, corresponding excitation energies and evaporation channels are proposed, such as the isotopes Bk-248,Bk-249 in Ca-48 induced reactions in 3n evaporation channels and the reactions Sc-45+Cm-246,Cm-248 in 3n and 4n channels, and the system V-51+Pu-244 in 3n channel.

Influence of entrance channels on the formation of superheavy nuclei in massive fusion reactions

Within the framework of the dinuclear system (DNS) model, the production cross sections of superheavy nuclei Hs (Z=108) and Z=112 combined with different reaction systems are analyzed systematically. It is found that the mass asymmetries and the reaction Q values of the projectile target combinations play a very important role on the formation cross sections of the evaporation residues. Both methods to obtain the fusion probability by nucleon transfer by solving a set of microscopically derived master equations along the mass asymmetry degree of freedom (ID) and distinguishing protons and neutrons of fragments (2D) are compared with each other and also with the available experimental data. (C) 2010 Elsevier B.V. All rights reserved.

Hemizygosity for Atm and Brca1 influence the balance between cell transformation and apoptosis

Background: In recent years data from both mouse models and human tumors suggest that loss of one allele of genes involved in DNA repair pathways may play a central role in genomic instability and carcinogenesis. Additionally several examples in mouse models confirmed that loss of one allele of two functionally related genes may have an additive effect on tumor development. To understand some of the mechanisms involved, we examined the role of monoallelic loss or Atm and Brca1 on cell transformation and apoptosis induced by radiation. Methods: Cell transformation and apoptosis were measured in mouse embryo fibroblasts (MEF) and thymocytes respectively. Combinations of wild type and hemizygous genotypes for ATM and BRCA1 were tested in various comparisons. Results: Haploinsufficiency of either ATM or BRCA1 resulted in an increase in the incidence of radiation-induced transformation of MEF and a corresponding decrease in the proportion of thymocytes dying an apoptotic death, compared with cells from wild-type animals. Combined haploinsufficiency for both genes resulted in an even larger effect on apoptosis. Conclusions: Under stress, the efficiency and capacity for DNA repair mediated by the ATM/BRCA1 cell signalling network depends on the expression levels of both proteins.