Mating system shifts a species’ range

Understanding the ecological and evolutionary mechanisms that shape a species’ range is an important goal in evolutionary biology. Evidence indicates that mating system is an effective predictor of the global range of native species or naturalized alien plants, but the mechanisms underlying this predictability are not elaborated. Here, we develop a theoretical model to account for the ranges of plants under different mating systems based on migration‐selection processes (an idea proposed by Haldane). The model includes alternation of gametophyte and sporophyte generations in one life cycle and the dispersal of haploid pollen and diploid seeds as vectors for gene flow. We show that the interaction between selfing rates and gametophytic selection determines the role of mating system in shaping a species’ range. Selfing restricts the species’ range under gametophytic selection in nonrandom mating systems, but expands the species’ range under the absence of gametophytic selection in any mating system. Gametophytic selection slightly restricts the species’ range in random mating. Both logarithmic and logistic models of population demography yield similar conclusions in the case of fixed or evolving genetic variance. The theory also helps to explain a broader relationship between mating system and range size following biological invasion or plant naturalization.     

Synthesis and biological evaluation of 18F labeled fluoro-oligo-ethoxylated 4-benzylpiperazine derivatives for sigma-1 receptor imaging

We report the synthesis and evaluation of a series of fluoro-oligo-ethoxylated 4-benzylpiperazine derivatives as potential σ₁ receptor ligands. In vitro competition binding assays showed that 1-(1,3-benzodioxol-5-ylmethyl)-4-(4-(2-fluoroethoxy)benzyl)piperazine (6) exhibits low nanomolar affinity for σ₁ receptors (K_i = 1.85 ± 1.59 nM) and high subtype selectivity (σ₂ receptor: K_i = 291 ± 111 nM; K_iσ₂/K_iσ₁ = 157). [¹⁸F]6 was prepared in 30–50% isolated radiochemical yield, with radiochemical purity of >99% by HPLC analysis after purification, via nucleophilic ¹⁸F^? substitution of the corresponding tosylate precursor. The log D_{pH 7.4} value of [¹⁸F]6 was found to be 2.57 ± 0.10, which is within the range expected to give high brain uptake. Biodistribution studies in mice demonstrated relatively high concentration of radiotracers in organs known to contain σ₁ receptors, including the brain, lungs, kidneys, heart, and spleen. Administration of haloperidol 5 min prior to injection of [¹⁸F]6 significantly reduced the concentration of radiotracers in the above-mentioned organs. The accumulation of radiotracers in the bone was quite low suggesting that [¹⁸F]6 is relatively stable to in vivo defluorination. The ex vivo autoradiography in rat brain showed high accumulation of radiotracers in the brain areas known to possess high expression of σ₁ receptors. These findings suggest that [¹⁸F]6 is a suitable radiotracer for imaging σ₁ receptors with PET in vivo.     

氢氧化细菌SDW-16的分离鉴定及促生特性

利用气体循环培养体系从沙打旺根际土壤分离得到1株氢氧化细菌SDW-16(GenBank登录号:KF835389),16S rDNA序列分析和生理生化特征鉴定其为荧光假单胞菌(Pseudomonas fluorescens)。菌株对植物促生机制的初步研究表明菌株SDW-16除具有铁载体分泌能力外,还具有产IAA和ACC脱氨酶活性,其中产IAA量为(21.62±0.30)μg/mL,ACC脱氨酶活力高达(8 372.17±805.43) nmol/(mg·h)。菌株SDW-16具有多项促生能力且均高于其他菌株,说明菌株SDW-16有较高的促生特性,同时也初步证明了氢氧化细菌的促生机制。     

外源脱落酸对富士苹果果实膨大后期光合产物向果实运输的影响

为了明确脱落酸(ABA)对苹果果实糖分积累的影响机理,本试验以5年生‘烟富3’/M26/平邑甜茶为试材,采用¹³C同位素标记技术,研究在果实膨大后期用不同浓度(0、50、100和150 mg·L^-1)脱落酸溶液及氟啶酮(ABA生物合成抑制剂)处理果实对光合产物向果实运输及糖代谢的影响.结果表明: 随着ABA浓度的增加,糖代谢相关酶活性、蔗糖转运蛋白基因MdSUT1、MdSUT2.2和山梨醇转运蛋白基因MdSUT3相对表达量呈先升高后降低趋势,均以100 mg·L^-1ABA处理时最高.氟啶酮处理显著抑制了糖代谢酶活性和糖转运蛋白基因相对表达量.与其他处理相比,100 mg·L^-1ABA处理显著减少了叶片¹³C含量,增加了果实¹³C含量,提升了光合产物由叶片向果实的运输速率.表明外源ABA通过增强果实库强,促进更多的光合产物向果实运输,提高了成熟期果实可溶性糖含量.     

Conformation and activity ofPhaseolus coccineus var. rubronanus lectin

The conformation of native and denaturedPhaseolus coccineus var. rubronanus lectin was studied by circular dichroism (CD) and correlated to the hemagglutinating activity. The far-UV CD spectrum at 25°C showed a broad, negative band around 223 nm and a positive one at 196 nm. CD data analysis of the lectin indicated a -sheet-rich protein. At high temperatures, the spectrum was blue-shifted with increasing magnitude; these changes correlated well with the loss of the activity. The conformation of lectin betweenpH 2 and 10 remained essentially unchanged. AtpH 13 the CD spectrum resembled that of unordered form with a negative band near 200 nm and the activity was completely lost. The denatured lectin in 6 M guanidine hydrochloride would be renatured upon diluting the denaturant to 0.75 M; the changes in CD spectrum again correlated well with the loss of the activity. The effect of sodium dodecyl sulfate on the lectin was drastic; it sharply increased thea-helix at the expense of the -sheet and reduced the activity; the changes reached a plateau above 20 mM surfactant.     

The mechanism involved in the loss of PTEN expression in NSCLC tumor cells

Loss of PTEN expression is observed in most non-small cell lung cancers (NSCLC). However, the mechanism by which PTEN expression is regulated in NSCLC has not been fully elucidated. In this study, we investigated the role of DNA methyltransferases (Dnmts), microRNA-29b (miR-29b), and anti-miR-29b inhibitor in PTEN promoter methylation and PTEN gene expression in H358 NSCLC cells in vitro and in vivo. PTEN mRNA was measured by RT-PCR. PTEN and Dnmts protein levels were measured by Western blot. miR-29b expression was detected by Northern blot. A xenograft H358 tumor mouse model was established by subcutaneously inoculating H358 cells into the right hind limbs of nude mice. We found that radiation induced cell apoptosis and hypomethylation in PTEN promoter, PTEN and miR-29b expression, and downregulation of Dnmt1, 3a and 3b expression in H358 tumor cells. The effect of radiation on gene expression and apoptosis was blocked by anti-miR-29b inhibitor. In the xenograft H358 tumor model, anti-miR-29b inhibitor reversed radiation-induced tumor growth delay, PTEN reexpression and downregulation of Dnmts expression. Our study suggested that miR-29b is an upstream molecule of PTEN. miR-29b regulates PTEN gene expression through downregulating Dnmts expression and subsequently induces hypomethylation in PTEN promoter. Targeting therapy could be established in NSCLC by upregulating miR-29b expression.     

High-mobility-group family genes from Lampetra japonica reveal their early origin and molecular evolution in the vertebrate lineage

High-mobility group family (HMG) genes are ubiquitous in vertebrates, including mammals, birds, amphibians and fishes. To elucidate the molecular phylogeny of the HMG genes in the primitive vertebrate, we have cloned three homologues of HMG-box genes, called Lj-HMGB1, Lj-HMGB2 and Lj-HMGBX, from a cDNA library generated from lymphocyte-like cells of the Japanese lamprey (Lampetra japonica), an Agnathan that occupies a critical phylogenetic position between invertebrates and vertebrates. The open reading frames of Lj-HMGB1, Lj-HMGB2 and Lj-HMGBX contained 627 bp, 585 bp and 678 bp, respectively. The analysis of the deduced amino acid sequences indicated that these three putative Lj-HMGB proteins contain four domains: HMG-box A, HMG-box B, an acidic carboxyl-terminal tail and a linker. A phylogenetic analysis revealed that the Lj-HMGB proteins fall outside the vertebrate clade; Lj-HMGBX is descended from a gene ancestral to the mammalian HMGB1/2/3. This discovery implies that there was a gene duplication event in the HMGB1/2/3 gene family that occurred after the divergence of the vertebrates (Cyclostomata) from the Cephalochordata and Urochordata at least 450 million years ago (MYA). The Lj-HMGB1, Lj-HMGB2 and Lj-HMGBX genes were detected in most tissues of the lamprey by RT-PCR. Our findings provide insight into the phylogeny of the HMGB genes in vertebrates.     

氨肽酶N的表达及其与结石形成的关系(英文)

 为研究大鼠高胆固醇饮食时 ,肝脏氨肽酶N(APN)在实验结石形成中可能的结石发生作用 ,采用 1.2 %胆固醇饮食 4周 ,诱发新西兰兔胆囊结石形成 .根据兔APN基因cDNA序列设计引物 ,提取肝脏总RNA .利用RT PCR检测肝脏APNmRNA水平的变化 ,用组织化学方法观察肝脏毛细胆管膜上APN的表达 .观察新西兰兔胆囊结石形成过程中肝脏APN的mRNA水平的变化、APN表达及胆汁中APN活性、胆脂、总蛋白含量的变化 ,探讨APN在胆石形成中可能的作用 .经成石饲料饲养后 ,随着胆汁饱和度增加和APN活性加强 ,胆囊结石组肝脏APNmRNA水平较对照组明显增高 ,胆囊结石组胆汁中总胆固醇、CSI、总蛋白浓度及APN活性均明显高于对照组 ,且胆汁中APN活性与肝脏APN的表达及胆汁CSI增高呈正相关 .结果提示 ,当存在胆汁过饱和的情况下 ,APN很可能作为促成核因子在胆结石形成早期发挥重要作用