粗枝云杉( Picea asperata Mast.)天然群体的遗传变异

西南地区在我国的经济发展和生态环境建设中占重要地位，但也是我国生态环境最脆弱的地区之一，生态系统退化，生态功能减弱，严重制约着西南林业的可持续经营与发展。本项目采用DNA 分子标记SSR 研究不同生境条件下粗枝云杉群体的遗传变异及其时空分布格局，考察遗传变异与复杂的山地生态环境间的潜在联系，系统地揭示粗枝云杉天然群体与环境系统相互作用的生态适应与分子进化机制。粗枝云杉适应性强，生长迅速，在植树造林和工业用材方面占有重要地位，研究成果可为中国西南部亚高山天然林的可持续经营及退化生态系统的恢复与重建提供理论依据和科学指导。主要研究结果如下： 1. SSR 位点变异丰富，等位基因频率的分布格局多样。7 个SSR 标记全是多态位点，每位点的等位基因数变化范围为13~24，平均为19.9 个。SSR 位点的等位基因片段长度范围变化较大。73.1%的等位基因变异遵循逐步突变模型(SSM)而发生1 个重复基元的变化，22.3%和4.6%的变异分别按两阶段突变模型(TMP)发生1 个重复基元以上的变化和在SSR 位点侧翼区发生1 个碱基变化的插入-删除事件。 2. 粗枝云杉拥有中等偏高水平的遗传多样性和相对大的群体间遗传分化。通过分析代表10 个群体的250 个个体在7 个SSR位点的变化，调查了源自中国西南山区的粗枝云杉的微卫星变异。相当高的遗传多样性和强烈的群体分化发生在粗枝云杉中， 其群体平均Nei's 期望杂合度为0.707 ， 群体间遗传距离为0.121~0.224(FST)和0.100~0.537(RST)。然而，群体间遗传距离与地理距离之间无相关性，从而排除了简单的距离分离模式并暗示迁移不是影响粗枝云杉遗传变异格局的主要因素。事实上，使用私有等位基因估算的基因流数量非常低，仅等于0.753。等位基因置换检验(Allele permutation tests)揭示逐步突变及遗传漂变都对群体间分化有贡献。另外，在多数位点检测到显著的群体间遗传差异，这个结果说明自然选择，假设通过环境压力，是引起粗枝云杉微地理分化的主要因素之一。根据SSR基因型，250 个粗枝云杉个体的70%被正确地归类入其各自的来源群体，结果表明微卫星(SSR)对区分来自中国不同生态地理位点的粗枝云杉基因型是有效的。 3. 在SSR、RAPD 和AFLP 位点，显著的群体间遗传结构被发现的，但三种标记间遗传分化程度和群体遗传关系有差异。利用来自10 个群体的247 个个体，我们报告了关于样本粗枝云杉群体间遗传关系的总体看法。根据各自对评价遗传关系的信息能力和适用性，SSR、RAPD 和AFLP 标记被选用，三种技术非常有效地区别这些基因型。使用的SSR、RAPD 和AFLP 标记分别估计平均Dice 相似性系数。Mantel 检验产生显著但相对低的共表型适合度(RAPD = 0.63£AFLP = 0.60和SSR = 0.75)。比较三种标记系统，RAPD 和AFLP 共表型指数相对高地相关(r =0.59)，而RAPD 和SSR 及SSR 和AFLP 之间的相关系数分别是0.53 和0.35。所有系统树，包括不同标记资料结合获得的系统树，反映了多数群体依据它们的地理条件而成某种特定关系。结果暗示单个或结合标记系统能用来深入洞察粗枝云杉遗传研究，并且不同标记系统合并资料能提供更可靠的信息。 Southwestern region plays an important role in economic developmentand ecological construction in China. Yet, it is also one of the weak regionsof ecological environment in China with degraded ecosystem and imperfectfunction, which restricts the sustaining management and development ofsouthwestern forestry. The genetic variation and spatial distribution patternof P. asperata populations originating from different habitats wereinvestigated using SSR molecular markers in this study. The correlationsbetween genetic variation and ecological and environmental conditionswere detected, and the interaction between P. asperata populations andenvironmental system and the mechanism of ecological adaption -molecular evolution were revealed. Given the significant ecological andeconomic roles of the fast-growing and wide-adaptive species in reforestation and production of pulp wood and timber, the study couldprovide a strong theoretical evidence and scientific direction for thesustaining management of subalpine natural forest, and the afforestationand rehabilitation of degraded ecosystem. The results are as follows: 1. The genetic variation at SSR loci was abundant and the distributionof allelic frequencies was uneven. All seven loci were polymorphic, and thenumber of alleles per locus varied from 13 to 24 with a mean valueequaling 19.9. The allele sizes at SSR loci were found to vary widely.73.1% of allelic variation followed stepwise mutation model (SSM) whichresults increase or decrease by one repeat type, and 22.3% and 4.6% wereresulted from two-phase mutation model (TMP) with allele size varying bymore than one repeat type and from insertion-deletion events in theflanking regions at SSR loci with a single basepair changing, respectively. 2. P. asperata possessed a moderate to high level of genetic diversityand considerable genetic differentiation. Microsatellite variation of P.asperata. originating from the mountains of southwestern China wasinvestigated by analyzing variation at seven SSR loci in 250 individualsrepresenting ten populations. A fair degree of genetic diversity and strongpopulation subdivision occurred with the mean gene diversity (H) of 0.707,and genetic distances among populations varying between 0.121 and 0.224(FST) and between 0.100 and 0.537 (RST). However, inter-populationgenetic distances showed no correlation with geographic distances between the population sites. This ruled out a simple isolation by distance modeland suggested that migration does not have a great impact. In fact, theamount of gene flow, detected using private alleles, was very low, equalingonly 0.753. Allele permutation tests revealed that stepwise-like mutations,coupled with genetic drift, could contribute to population differentiation.Moreover, significant genetic differences between populations weredetected at most loci. The results indicate that natural selection, presumablythrough environmental stress, may be one of the main factors causingmicro-geographical differentiation in the genetic structure of P. asperata.Based on SSR genotypes, 70% of the 250 individuals were correctlyclassified into their sites of origin. This suggests that microsatellites (SSRs) are effective in distinguishing genotypes of P. asperata originating fromdiverse eco-geographical sites in China. 3. Using a set of 247 individuals from ten P. asperata populations wereport an overview on the genetic relationship among the sampled P.asperata populations. RAPD, AFLP and SSR were used in terms of theirinformativeness and applicability for evaluate relationship and all threetechniques discriminated the genotypes very effectively. Mean Dicesimilarities coefficient were estimated using RAPD, AFLP and SSR,respectively. The Mantel test resulted in a significant but relatively low fit(RAPD = 0.63, AFLP = 0.60 and SSR = 0.75) of cophenetic values.Comparing the three marker systems to each other, RAPD and AFLP cophenetic indices were highly correlated (r = 0.59), while correlationcoefficient between RAPD and SSR was r = 0.53 and between SSR andAFLP was r = 0.35. For all markers a relatively high similarity indendrogram topologies was obtained although some differences wereobserved. All the dendrograms, including that obtained by the combineduse of all the marker data, reflect some relationships for most of thepopulations according to their geographic conditions. The results indicatethat single or combined marker system could be used to insight into geneticstudy in P. asperata and the combined data of different marker systems canprovide more reliable information.

黄河上游青海沙蜥种组的系统地理学研究

沙蜥属（Phrynocephalus）的卵胎生类群主要分布在我国青藏高原，包括南疆沙蜥（P. forsythii）、西藏沙蜥（P. theobaldi）、红尾沙蜥（P. erythrurus）、贵德沙蜥（P. putjatia）和青海沙蜥（P. vlangalii）。其卵胎生生殖方式适应了高寒生境，与青藏高原隆升有关。纵观前人的研究，上述几种卵胎生沙蜥的分类、系统发育关系以及生物地理都还存在疑问。本文研究了分布在若尔盖湿地的青海沙蜥红原亚种（P. v hongyuanensis）以及分布在黄河上游其它地区青海沙蜥种组的地理分布格局，并探讨了其形成机制。 青海沙蜥在黄河上游主要分布于若尔盖湿地以及青海湖周边地区。若尔盖湿地青海沙蜥红原亚种的生境由于沼泽的形成被切割成不连续的斑块，通过遗传分析可以推测这种特殊生境对它们遗传结构的影响。其次，贵德沙蜥、青海沙蜥的青海湖周边各居群以及若尔盖湿地居群之间的系统地理格局还未见报道。因此本文以居群为单位，将它们作为一个复合体，通过系统地理研究，可以了解其种群遗传结构，据此分析相关的地质历史事件对其分布的影响。主要结果如下： 1. 若尔盖湿地青海沙蜥红原亚种的种群遗传结构： 共研究了三个地理单元（红原（HY）、辖曼（XM）、玛曲（MQ））的7个采集点的72个个体。所有ND4-tRNALeu序列比对得到785 bp的片断，定义了9种单倍型。结果显示总的核苷酸多样性较低，单倍型多样性较高。分子变异分析（AMOVA）显示3个单元间差异显著（P<0.01），遗传变异主要存在于地理单元间，占62.61%。除MQ单元，XM各居群与HY居群混杂在一起，单倍型网络图没有显示出单倍型和地理位置的对应关系。XM单元单倍型的不配对分布（Mismatch distribution）为明显左移的单峰，且Fu’s Fs test为负值，表明XM单元可能经历了近期种群扩张，有足够的时间积累单倍型的多态性，还不足以大幅提高核苷酸多样性，这是其单倍型多样性较高和核苷酸多样性较低的原因。MQ单元遗传多样性低而与其他单元显著分化，推测这与3万年前黄河在若尔盖玛曲之间贯通有关。近期沼泽的形成对XMb居群的隔离时间短，使得其遗传多样性低但还不足以形成大的遗传差异。无论黄河的贯通还是沼泽的形成其隔离形成的时间都不长，其作用改变了单倍型出现的频率，也出现了一些特有单倍型，但共享单倍型还广泛存在，还不足以使得不同居群之间形成较大的遗传距离。 2. 黄河上游青海沙蜥种组的分布格局与地史过程的关系： 黄河上游青海沙蜥种组包括贵德沙蜥、青海沙蜥指名亚种的青海湖周边各居群、青海沙蜥红原亚种若尔盖湿地居群、以及青海湖以西的部分居群（序列由Genbank下载获得），总计22个居群189个样品。所有ND4-tRNALeu序列比对得到703个位点，定义了39种单倍型。以南疆沙蜥为外群构建的贝叶斯树以及MP法构建的无根树，都分为A、B两大组。其中A包括若尔盖湿地居群以及玛多居群（A1）、青海湖以西的居群和兴海居群（A2）、西藏沙蜥；B包括青海湖以南的居群和天祝居群（B1）、青海湖以东北的居群（B2）。单倍型网络图分别对应了系统发育树上的各支。按照系统发育结果分组进行分子变异分析，得到组间变异占88.63％，各组间差异显著（P=0.000）。种群遗传结构分析得到，A1和B2可能经历了近期的种群扩张，前者扩张时间约为0.105－0.189 Ma B.P.（million years before present），后者为0.057－0.102 Ma B.P.，可能与末次间冰期的气候变暖有关。A2和B1对应的两个地理单元都具有较强的种群遗传结构，较为稳定。 青海沙蜥种组A、B两大支之间遗传距离大，分化明显，分化大约发生在4.29－2.38 Ma B.P.，推测青藏运动的A幕运动后复杂的地形变化可能是它们产生分化的原因。B1和B2分化大约发生在1.73－0.96 Ma B.P.，这与湟水流域构造运动发生的时间相符。在早、中更新世时期，B1支内部各居群可能有交流，中更新世末共和盆地出现的抬升以及河流溯源改道等事件可能是引起这支内部多个单倍型丢失的原因。A1、A2支的分化可能与倒数第三次冰期降临之后气候变冷、阿尼玛卿山的大冰帽有关。 The viviparous group of genus Phrynocephalus is mainly distributed in the Qinghai –Tibetan Plateau, including P. forsythii、P. theobaldi、P. erythrurus、P. putjatia and P. vlangalii. These species are adapted well to the cold clime there, and the origin of this group was the result of a vicariance event associated with the uplifting of the Qinghai -Tibetan Plateau. Although many works have been done, there are still several questions about classification、phylogenetic relationships and the biogeography of this group. The phylogeographic pattern of the P. vlangalii complex on the upper reaches of the Yellow River and the P. v. hongyuanensis in Zoige Wetland were studied in this thesis. On the upper reaches of the Yellow River, P. vlangalii complex are distributed in Zoige Wetland and the southeast and northeast region of Kuku-noor Lake. Because of the forming of the wetland in Zoige, the habitats for sand lizards are divided into many discontinuous ones, and it is necessary to analyze genetic structure in these unique habitats. The phylogeographic patter among P. putjatia、populations of P. vlangalii in the southeast region of Kuku-noor Lake and populations of P. vlangalii in Zoige Wetland hasn’t been studied yet, and the complicated geological events of the Plateau may play an important role in the populations’ diversity and species forming there. So these populations were gathered as a complex, and phylogeographic analysis were used to clarify these doubts. According to the two topics above, this thesis has two parts of results as follows: 1. Three geographic units of P. vlangalii hongyuanensis in Zoige Wetland were defined, and they were Xiaman （XM）、Hongyuan （HY） and Maqu （MQ）. 785bp fragments of the mtDNA ND4-tRNAleu were determined from 72 samples and nine haplotypes were identified. As a whole, the nucleotide diversity was low，but the haplotype diversity was high. Analysis of molecular variance （AMOVA） showed that the three units were distinctly different（P<0.01），and 62.61% of the total genetic diversity was attributable to variation among units. There were 3 haplotypes shared among XM and HY，and no geographic clustering was observed except MQ from the TCS network. The results from the mismatch distribution analysis and Fu’s Fs test implied that there might be a recent population expansion in the XM unit, and this may be the reason why XM had a high haplotype diversity but a low nucleotide diversity. We estimate that the MQ and XMb have lower diversities because of some very recent geographic events, such as the formation of the Yellow river’s upriver and the Zoige Wetland. Although they are distinctly different, not enough time has passed for them to have diverged a great genetic distance. 2. 189 samples in 22 populations of P. vlangalii complex were collected, including P. putjatia、populations of P. vlangalii in the southeast and northeast region of Kuku-noor Lake、 populations of P. vlangalii in Zoige Wetland and the data from Genbank. 703bp ND4-tRNALeu sequences identified 39 haplotypes. P. forsythii was selected as outgroup, and both the Bayesian tree and the MP unrooted tree were divided into two groups（A、B）. A included populations in Zoige Wetland and Xinghai（A1）、populations in the west of Kuku-noor Lake（A2）、P. theobaldi, and B included populations in the southeast of Kuku-noor Lake and Tianzhu（B1）、populations in the northeast of Kuku-noor Lake（B2）. The haplotype network agreed with these groups. AMOVA showed that these five groups were distinctly different（P<0.01）, and 88.63% of the total genetic diversity was attributable to variation among groups. There might be recent population expansion in A1 and A2, which corresponded to the dry climate of the last interglacial period. The expansion times were 0.189-0.105 Ma B.P. and 0.102-0.057 Ma B.P., respectively. A2 and B1 had strong genetic structure. The large genetic distance between A and B showed that they had been separated from each other for a long time（about 4.29-2.38 Ma B.P.）, and it corresponded to the A phase of Qingzang Movement. The diversity between B1 and B2 at 1.73-0.96 Ma B.P. may be caused by the geological event in Huangshui valley. In early Pleistocene, populations in B1 may have gene flow because of geographic linkage, and later the uplift of the Plateau and the change of river route there made a few haplotypes lost. A1 and A2 were divided into two parts by A’nyemaqen Mountains at 0.66-0.37 Ma B.P., which maybe corresponded to glaciations at about 0.7 Ma B.P.

Drift distance survey in direct plasma injection scheme for high current beam production

In a laser ion source, plasma drift distance is one of the most important design parameters. Ion current density and beam pulse width are defined by plasma drift distance between a laser target and beam extraction position. In direct plasma injection scheme, which uses a laser ion source and a radio frequency quadrupole linac, we can apply relatively higher electric field at beam extraction due to the unique shape of a positively biased electrode. However, when we aim at very high current acceleration such as several tens of milliamperes, we observed mismatched beam extraction conditions. We tested three different ion current at ion extraction region by changing plasma drift distance to study better extraction condition. In this experiment, C6+ beam was accelerated. We confirmed that matching condition can be improved by controlling plasma drift distance.

Relationship between the continually expanded interlayer distance of layered silicates and excess intercalation of cationic surfactants

Excess intercalation of cationic surfactants into Na-montmorillonites (MMTs) was investigated in organically modified silicates (OMSs), synthesized with MMTs and octadecylammonium chloride (OAC) by systematically varying the surfactant loading level from 0.625 to 1, 1.25, 1.56, 2, and 2.5 with respect to the cation exchange capacity (CEC) of MMTs. Wide-angle X-ray diffraction and thermogravimetric analysis results indicated that the continuous increase of interlayer distances came from the entering of surfactants into the interlayer of MMTs. Excess surfactants were extracted with a Soxhlet apparatus, which showed two kinds of intercalation states of surfactants in the interlayer when the surfactant loading level was beyond the CEC. Fourier transform infrared spectroscopy and differential scanning calorimetry were used to explore the microstructures of OMSs. It was found that the surfactants arranged more orderly as the loading level increased and the excess surfactants piled up in the interlayer together with counterions, forming a sandwiched surfactant layer. On the basis of the results, the layer structures of OMSs and the mechanism by which the surfactants entered the interlayer were expounded: surfactant cations entered the interlayer through cation exchange reactions and were tightly attracted to the silicate platelet surfaces when the surfactant loading level was below the CEC;

Brittle-tough transition in PP/EPDM blends: effects of interparticle distance and tensile deformation speed

The toughness of polypropylene (PP)/ethylene-propylene-diene monomer rubber (EPDM) blends containing various EPDM contents as a function of the tensile speed was studied. The toughness of the blends was determined from the tensile fracture energy of the side-edge notched samples. A sharp brittle-tough transition was observed in the fracture energy versus interparticle distance (ID) curves when the crosshead speed < 102.4 mm/min. It was observed that the brittle-ductile transition of PP/EPDM blend occurred either by reducing ID or by decreasing the tensile speed. The correlation between the critical interparticle distance and tensile deformation rate was compared with that between the critical interparticle distance and temperature for PP/EPDM blends. (C) 2000 Elsevier Science Ltd. All rights reserved.

Brittle-ductile transition in high-density polyethylene/glass-bead blends: Effects of interparticle distance and temperature

The toughness of high-density polyethylene (HDPE)/glass-bead blends containing various glass-bead contents as a function of temperature was studied. The toughness of the blends was determined from the notch Izod impact test. A sharp brittle-ductile transition was observed in impact strength-interparticle distance (ID) curves at various temperatures. The brittle-ductile transition of HDPE/glass-bead blends occurred either with reduced ID or with increased temperature. The results indicated that the brittle-ductile-transition temperature dropped markedly with increasing glass-bead content. Moreover, the correlation between the critical interparticle distance (ID.) and temperature was obtained. Similar to the ID, of polymer blends with elastomers, the ID, nonlinearly increased with increasing temperature. However, this was the first observation of the variation of the ID, with temperature for polymer blends with rigid particles. (C) 2001 John Wiley & Sons, Inc. J Polym. Sci Part B: Polym. Phys 39: 1855-1859, 2001.

Atom space distance and computing of molecular similarity

A mathematical model on computation of molecular similarity was suggested, The algorithmic techniques for measuring the degree of similarity between pairs of three-dimensional chemical molecules was represented by modified interatomic distance matrices. Current work was carried out on Indigo 2 work station with Sybyl software. Four groups of molecules were used to compute the molecules similarity to testing the mathematical model with satisfactory results.

Effect of polymer chain structure and chain distance on luminescent efficiency

Three kinds of PPV-based copolymers were synthesized and characterized. Their luminescent properties were investigated and discussed by PL spectrum, and time-dependence luminescent spectrum in film and solution stare. The results show that in the range of our study, the PL intensity and lifetime of luminescent decay increase with the increasing length of flexible segments and the solution diluting, indicating the tendency of the increase of luminescent efficiency.

Interparticle distance-temperature-strain rate equivalence for the brittle-tough transition in polymer blends

From the angle of energy transformation an equation was obtained for the brittle transition in polymer blends. The effects of interparticle distance, temperature and strain rate on the brittle-tough transition in polymer blends were characterized by this equation. The calculations show that, for this transition: (1) increasing temperature and decreasing interparticle distance are equivalent and the shift factor increases with increasing temperature; (2) decreasing strain rate and decreasing interparticle distance have equivalent effects on the transition; (3) the strain rate must be optimum in order to find the brittle-tough transition phenomena for a given temperature region. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.

Studies on hybridization effects of different geographic populations of Chlamys farreri - II. The medium-term growth and development of Chlamys farreri populations from China and Russia and their reciprocal crosses

Based on the research of juvenile (2, 3, 4 months) growth and survival of three populations of two different geographic areas in Chlamys farreri from Russian and China and their F, hybrids derived from Chinese cultural population (CC) female x Russian population (RW) male, Chinese wild population (CW) female x Russian population (RW) male, Russian population (RW) female x Chinese wild population (CW) the study of the medium-term (6, 8, 10, 12 months) growth and development of Chlamys farreri was carried out. The four determined results indicated that there existed different extent heterosis (3% similar to 52 %) for the growth in three types of F-1 hybrids, and the offspring derived from CC female X Rmale had a stronger heterosis among the crosses at the medium-term; the uptrend among traits are wet weight > shell width > shell length > shell height, Chinese cultural population could be recognized as excellent parent, and seasonal variations influence very much on the daily increment and growth rate of each trait of Chlamys farreri and it is only able to survive and could barely grow in winter (6 similar to 8 months), but grows fast in temperate season (10similar to12 months).