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孢粉学是解决植物分类中疑难类群物种微形态分化的重要方法,随着分子系统学的发展,结合这两门学科的优势可以更加有效地解决疑难类群的分类学问题。鳞盖蕨属(Microlepia)是一个分类困难的疑难类群,采用孢粉学与分子系统学一一对应的方法,以及居群取样方式,选取280份样本,联合4个叶绿体片段(rbcL、trnL-F、psbA-trnH和rps4),采用最大似然法和贝叶斯法构建该属的系统发生关系,在此基础上对凭证标本中100份材料的孢子进行观察和分析。综合分子系统学和孢粉学的研究结果,得出结论:(1)在形态学研究中广泛被接受的15个物种得到了单系支持,并厘清了分类困难的复合群;(2)发现边缘鳞盖蕨(M. marginata)可能存在隐性种;(3)建议恢复过去归并处理为异名的瑶山鳞盖蕨(M. yaoshanica)、罗浮鳞盖蕨(M. lofoushanensis)、四川鳞盖蕨(M. szechuanica)以及滇西鳞盖蕨(M. subspeluncae);(4)提出鳞盖蕨属可能存在杂交现象;(5)提出鳞盖蕨属完整的属下分类建议。 相似文献
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An advanced electro-active dry adhesive,which was composed of a mushroom-shaped fibrillar dry adhesive array actuated by an Ionic Polymer Metal Composite (IPMC) artificial muscle reinforced with nitrogen-doped carbon nanocages (NCNCs),was developed to imitate the actuation of a gecko's toe.The properties of the NCNC-reinforced Nafion membrane,the electromechanical properties of the NCNC-reinforced IPMC,and the related electro-active adhesion ability were investigated.The NCNCs were uniformly dispersed in the 0.1 wt% NCNC/Nafion membrane,and there was a seamless connection with no clear interface between the dry adhesive and the IPMC.Our 0.1 wt% NCNC/Nafion-IPMC actuator shows a displacement and force that are 1.6-2 times higher than those of the recast Nafion-IPMC.This is due to the increased water uptake (25.39%) and tensile strength (24.5 MPa) of the specific 3D hollow NCNC-reinforced Nafion membrane,as well as interactions between the NCNCs and the sulfonated groups of the Nafion.The NCNC/Nafion-IPMC was used to effectively actuate the mushroom-shaped dry adhesive.The normal adhesion forces were 7.85 mN,12.1 mN,and 51.7 mN at sinusoidal voltages of 1.5 V,2.5 V,and 3.5 V,respectively,at 0.1 Hz.Under the bionic leg trail,the normal and shear forces were approximately 713.5 mN (159 mN·cm-2) and 1256.6 mN (279 mN·cm-2),respectively,which satisfy the required adhesion.This new electro-active dry adhesive can be applied for active,distributed actuation and flexible grip in robots. 相似文献
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不同pH缓冲液对由乙酸产甲烷菌群结构的影响 总被引:1,自引:0,他引:1
【目的】研究不同p H缓冲液对乙酸产甲烷过程及对细菌和古菌群落结构的影响。【方法】分别添加磷酸盐(PB)、4-羟乙基哌嗪乙磺酸(HEPES)、哌嗪-1,4-二乙磺酸(PIPES)和Na HCO3/CO2缓冲液到乙酸产甲烷菌系中,定期监测甲烷产生趋势,到稳定期后收集菌体,进行16S rRNA基因的末端限制性片段多态性分析(T-RFLP)。【结果】发现PB组的乙酸产甲烷菌系延滞期约为40d,显著高于其他组的20-24 d(P0.05);Na HCO3/CO2组乙酸转化为甲烷的比例为(88.3±0.5)%,显著高于其他组的77%-81%(P0.05);不同缓冲液组的最大甲烷比生长速率为0.46-0.57 d-1(P0.05);Na HCO3/CO2组的细菌群落变化最明显,主要是未培养细菌(unclassified bacteria)、螺旋菌科细菌(Spirochaetaceae)和未培养WWE1类群的丰度较其他组分别增加到(15.5±9.4)%、(7.3±4.6)%和(17.6±6.3)%,而互养菌科(Synergistaceae)的细菌丰度降低到(8.9±8.1)%。AC+PB组中的古菌类群发生了明显变化,以竹节状甲烷鬃毛菌(Methanosaeta harundinacea)相关的产甲烷古菌占主导(97±2%),而在HEPES、PIPES和Na HCO3/CO2组和不加缓冲液组中同时存在两类乙酸营养型产甲烷古菌M.harundinacea和联合鬃毛甲烷菌(Methanosaeta concilii),以及属于甲烷杆菌目(Methanobacteriales)的氢营养型产甲烷古菌。【结论】在乙酸产甲烷菌系中加入PB增加了甲烷产生的延滞期,加入Na HCO3/CO2增加了甲烷产量,但是添加p H缓冲液不会影响到菌系的最大甲烷比生长速率。加入PB和Na HCO3/CO2都会显著改变微生物的菌群结构。这些研究为设计适宜的产甲烷菌系生长条件提供了参考。 相似文献
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除了细胞质膜,革兰氏阴性细菌细胞还有一层组成细胞壁的外膜(Outer Membrane)。膜蛋白是外膜的主要组成成分之一,绝大多数外膜蛋白是由反向平行的β-折叠(β-Strands)通过相邻的氢键结合形成的β-桶状结构蛋白(β-Barrel Proteins)。这些蛋白既可作为通道蛋白、转运蛋白、酶、受体、毒力因子,也可作为结构蛋白发挥稳定外膜的重要作用,它们是否正确折叠并整合到外膜对革兰氏阴性细菌的生存至关重要。大多数外膜蛋白易于重组表达和体外重折叠(in vitro refolding),并且折叠状态可通过多种方法测定,因此β-桶状结构外膜蛋白被当着模式蛋白来研究各类生物和非生物因子对膜蛋白折叠的影响,是膜蛋白研究的一大热点。本文将从β-桶状结构外膜蛋白体外折叠的研究方法和影响折叠的因素角度对近年相关研究进展进行综合述评,最后总结了外膜蛋白体外折叠模式,并结合作者的相关研究结果和观点对该领域的研究前景进行了展望。 相似文献
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Hanshu Wang Guishuan Wang Yubing Dai Zhenhua Li Yu Zhu Fei Sun 《Molecular reproduction and development》2019,86(9):1199-1209
G kinase‐anchoring protein 1 (GKAP1) is a G kinase‐associated protein that is conserved in many eutherians and is mainly expressed in the testis, especially in spermatocytes and round spermatids. The function of GKAP1 in the testis is largely unknown. Here, we revealed that deletion of GKAP1 led to an increase in sperm production with swollen epididymis, and germ cell apoptosis was found to decrease in GKAP1 knock‐out mice. Further investigations showed that a deficiency of GKAP1 could partly change the cellular location of cGK‐Iα and increase the amount of active cAMP response element‐binding protein (CREB) in the nucleus. Therefore, the expression of a particular inhibitor of apoptosis proteins (IAPs) was upregulated because of the activation of CREB, and this increase in IAPs was associated with a decrease in the level of activated caspase‐3. These results suggest that a deficiency of GKAP1 in mouse testis could increase sperm production through a reduction of the spontaneous apoptosis of germ cells in the testis, possibly because of a change in the activity of the cGK‐Iα pathway. 相似文献
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Abscisic acid (ABA) is the most important stress hormone in the regulation of plant adaptation to drought. Owing to the chemical instability and rapid catabolism of ABA, ABA mimic 1 (AM1) is frequently applied to enhance drought resistance in plants, but the molecular mechanisms governed by AM1 on improving drought resistance in Brassica napus are not entirely understood. To investigate the effect of AM1 on drought resistance at the physiological and molecular levels, exogenous ABA and AM1 were applied to the leaves of two B. napus genotypes (Q2 and Qinyou 8) given progressive drought stress. The results showed that the leaves of 50 µM ABA- and AM1-treated plants shared over 60% differential expressed genes and 90% of the enriched functional pathways in Qinyou 8 under drought. AM1 affected the expression of the genes involved in ABA signaling; they down-regulated pyrabactin resistance/PYR1-like (PYR/PYLs), up-regulated type 2C protein phosphatases (PP2Cs), partially up-regulated sucrose non-fermenting 1-related protein kinase 2s (SnRK2s), and down-regulated ABA-responsive element (ABRE)-binding protein/ABRE-binding factors (AREB/ABFs). Additionally, AM1 treatment repressed the expression of photosynthesis-related genes, those mainly associated with the light reaction process. Moreover, AM1 decreased the stomatal conductance, the net photosynthetic rate, and the transpiration rate, but increased the relative water content in leaves and increased survival rates of two genotypes under drought stress. Our findings suggest that AM1 has a potential to improve drought resistance in B. napus by triggering molecular and physiological responses to reduce water loss and impair growth, leading to increased survival rates. 相似文献
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