History vs. habitat type: explaining the genetic structure of European nine‐spined stickleback (Pungitius pungitius) populations

The genetic structure of contemporary populations can be shaped by both their history and current ecological conditions. We assessed the relative importance of postglacial colonization history and habitat type in the patterns and degree of genetic diversity and differentiation in northern European nine‐spined sticklebacks (Pungitius pungitius), using mitochondrial DNA (mtDNA) sequences and 12 nuclear microsatellite and insertion/deletion loci. The mtDNA analyses identified – and microsatellite analyses supported – the existence of two historically distinct lineages (eastern and western). The analyses of nuclear loci among 51 European sites revealed clear historically influenced and to minor degree habitat dependent, patterns of genetic diversity and differentiation. While the effect of habitat type on the levels of genetic variation (coastal > freshwater) and differentiation (freshwater > coastal) was clear, the levels of genetic variability and differentiation in the freshwater sites were independent of habitat type (viz. river, lake and pond). However, levels of genetic variability, together with estimates of historical effective population sizes, decreased dramatically and linearly with increasing latitude. These geographical patterns of genetic variability and differentiation suggest that the contemporary genetic structure of freshwater nine‐spined sticklebacks has been strongly impacted by the founder events associated with postglacial colonization and less by current ecological conditions (cf. habitat type). In general, the results highlight the strong and persistent effects of postglacial colonization history on genetic structuring of northern European fauna and provide an unparalleled example of latitudinal trends in levels of genetic diversity.     

DNA-based analysis of planktonic methanotrophs in a stratified lake

1. The assemblage of planktonic methanotrophs in a stratified freshwater lake was investigated. Vertical patterns were analysed by denaturing gradient gel electrophoresis, using the primer pair specific for 16S rRNA genes of type I methanotrophs.
2. The resulting banding patterns could be divided into three distinct groups, and sequenced bands were all related to the Methylobacter species. No amplicon was obtained with the primer pair specific for type II methanotrophs.
3. Cloning analysis of the pmoA gene was performed using samples from three water depths (epilimnion, metalimnion and hypolimnion). The compositions of the clone libraries from the three depths were distinct from each other but all three libraries were dominated by clones related to Methylobacter species.     

Quantitative trait loci controlling aluminium tolerance in two accessions of Arabidopsis thaliana (Landsberg erecta and Cape Verde Islands)

Quantitative trait loci (QTL) analysis of aluminium (Al) tolerance was performed using Ler/Cvi recombinant inbred (RI) lines of Arabidopsis thaliana. Relative root length (RRL) (root length with 4 µm Al/root length with no Al at pH 5.0) on day 5 was used as the Al tolerance index for QTL analysis. Al tolerance judged by RRL was well correlated to tolerance judged by other indexes, including accumulation of callose, reactive oxygen species in the root apex and growth performance on acid soil containing a large amount of exchangeable Al. Using data sets with an h_b² of 0.91, two QTLs were detected at the top of chromosome 1 and bottom of chromosome 3. These QTLs explained 40 and 16% of the phenotypic variation of Al tolerance, respectively, and the positive effect of the Cvi allele. The QTL on chromosome 1 overlapped with a major QTL in another recombinant inbred population, and is possibly related to malate excretion. A complete pair-wise search revealed 11 sets of epistatic interacting loci pairs, which accounted for the transgressive segregation among the RI population. Several epistatic interactions shared the same chromosomal region, indicating the possible involvement of regulatory proteins in Al tolerance in Arabidopsis.     

均匀设计超声波提取豆粕异黄酮的研究

本该采用均匀设计方法试验优化技术,进行超声波循环提取豆粕异黄酮的多因素复杂试验,通过应用统计分析软件SPSS处理试验数据,得出多因素回归方程,求出最佳试验条件,并通过试验进行验证．     

具核梭杆菌对结直肠癌细胞增殖、迁移及上皮间质转化作用的影响

【目的】评估具核梭杆菌对人结直肠癌细胞HCT116和人正常结肠上皮细胞HCoEpiC的增殖、黏附、凋亡、迁移、侵袭和上皮间质转化的影响。【方法】本研究用不同感染复数(MOI)Fusobacterium nucleatum ATCC 23726感染人结直肠癌细胞HCT116和人正常结肠上皮细胞HCoEpiC,建立感染模型;用3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐[3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide,MTT]、平板克隆、细胞划痕及侵袭(transwell)实验检测两组细胞的增殖、迁移和侵袭的变化;用流式细胞仪检测两组细胞凋亡情况;通过Western blotting检测两组细胞上皮标记物上皮细胞钙黏蛋白(E-cadherin)、Catenin δ-1蛋白、间充质标记物N-钙粘蛋白(N-cadherin)和波形蛋白(vimentin)表达水平的变化。【结果】F.nucleatum可促进HCT116细胞增殖,诱导HCT116细胞的迁移和侵袭,但不能引起细胞凋亡;可抑制HCoEpiC细胞的增殖、迁移和侵袭,并加速其凋亡;对HCT116和HCoEpiC细胞表现出很强的粘附能力,致细胞分散和拉长,细胞间粘附减少;使HCT116和HCoEpiC细胞上皮标记物E-cadherin与Catenin δ-1的表达量减少,间充质标记物N-cadherin与vimentin的表达量上升,E-cadherin由细胞膜向细胞质转移。【结论】F.nucleatum可诱导结直肠癌细胞和人正常结肠上皮细胞发生上皮间质转化,但抑制人正常结肠细胞的增殖、迁移和侵袭,表现出与结直肠癌细胞相反的作用。     

Mesophyll conductance decreases in the wild type but not in an ABA‐deficient mutant (aba1) of Nicotiana plumbaginifolia under drought conditions

Under drought conditions, leaf photosynthesis is limited by the supply of CO₂. Drought induces production of abscisic acid (ABA), and ABA decreases stomatal conductance (g_s). Previous papers reported that the drought stress also causes the decrease in mesophyll conductance (g_m). However, the relationships between ABA content and g_m are unclear. We investigated the responses of g_m to the leaf ABA content [(ABA)_L] using an ABA‐deficient mutant, aba1, and the wild type (WT) of Nicotiana plumbaginifolia. We also measured leaf water potential (Ψ_L) because leaf hydraulics may be related to g_m. Under drought conditions, g_m decreased with the increase in (ABA)_L in WT, whereas both (ABA)_L and g_m were unchanged by the drought treatment in aba1. Exogenously applied ABA decreased g_m in both WT and aba1 in a dose‐dependent manner. Ψ_L in WT was decreased by the drought treatment to ?0.7 MPa, whereas Ψ_L in aba1 was around ?0.8 MPa even under the well‐watered conditions and unchanged by the drought treatment. From these results, we conclude that the increase in (ABA)_L is crucial for the decrease in g_m under drought conditions. We discuss possible relationships between the decrease in g_m and changes in the leaf hydraulics.     

连香树生理生化物质随海拔的变化及其适应性研究

通过分析四川甘洛马鞍山自然保护区内不同海拔(A1:1874m,A2:1996m,A3:2160m,A4:2290m)梯度连香树的分布状况以及生理指标含量的变化,探讨了连香树对不同环境的适应能力。结果表明:随着海拔的升高,样方内连香树的总数、株高、幼树数量及树冠投影面积值均呈降低趋势,且海拔越高,其它物种抢占的空间资源越多以及环境变恶劣,连香树的适应能力下降;各种生理指标的变化为:叶绿素a、叶绿素b、叶绿素(a+b)和类胡萝卜素含量在A1处均高于A2、A3、A4处。A4与A1相比,叶绿素b、叶绿素(a+b)分别下降了42.42%和33.96%,差异显著。超氧化物歧化酶(SOD)活性、可溶性糖含量均随着海拔升高呈下降趋势,A4与A1相比,分别下降了52.74%、66.17%,差异显著;丙二醛(MDA)和游离脯氨酸(Pro)含量均随着海拔升高呈上升趋势,A4与A1相比,分别升高了3.98倍、4.43倍,差异显著;可溶性蛋白含量呈先降后升趋势,A1、A3、A4处均高于A2处。综合本次研究表明:A1处最适合连香树的生长、A4处连香树生长最差。     

IL34转基因小鼠的建立和表型分析

目的建立白介素34转基因小鼠,研究该基因在小鼠中表达对小鼠免疫系统的作用。方法把人的IL34基因插入CMV启动子下,构建转基因表达载体,通过显微注射法建立IL34转基因C57BL/6J小鼠。PCR鉴定IL34转基因小鼠的基因表型,Western blotting检测IL34蛋白的表达水平,组织化学染色观察IL34转基因小鼠重要器官的病理改变。结果建立了2个品系的IL34转基因小鼠。转入的人IL34基因在脾脏中的表达水平高于内源性IL34。组织学分析显示IL34转基因小鼠各重要器官如脑,心,肝,肾,肠等的形态结构均正常,但脾脏的生发中心比较活跃,白髓的范围比野生型小鼠大。结论成功建立了IL34转基因小鼠,IL34基因的过度表达对免疫系统作用需要进一步探讨。     

Differential responses in two varieties of winter wheat to elevated ozone concentration under fully open‐air field conditions

Two modern cultivars [Yangmai16 (Y16) and Yangfumai 2 (Y2)] of winter wheat (Triticum aestivum L.) with almost identical phenology were investigated to determine the impacts of elevated ozone concentration (E‐O₃) on physiological characters related to photosynthesis under fully open‐air field conditions in China. The plants were exposed from the initiation of tillering to final harvest, with E‐O₃ of 127% of the ambient ozone concentration (A‐O₃). Measurements of pigments, gas exchange rates, chlorophyll a fluorescence and lipid oxidation were made in three replicated plots throughout flag leaf development. In cultivar Y2, E‐O₃ significantly accelerated leaf senescence, as indicated by increased lipid oxidation as well as faster declines in pigment amounts and photosynthetic rates. The lower photosynthetic rates were mainly due to nonstomatal factors, e.g. lower maximum carboxylation capacity, electron transport rates and light energy distribution. In cultivar Y16, by contrast, the effects of E‐O₃ were observed only at the very last stage of flag leaf ageing. Since the two cultivars had almost identical phenology and very similar leaf stomatal conductance before senescence, the greater impacts of E‐O₃ on cultivars Y2 than Y16 cannot be explained by differential ozone uptake. Our findings will be useful for scientists to select O₃‐tolerant wheat cultivars against the rising surface [O₃] in East and South Asia.