沙漠腹地天然绿洲胡杨和柽柳叶片δ13C值对不同地下水埋深的响应

干旱区植物的水分利用效率对植物的分布及水分利用状况具有重要意义。基于不同地下水埋深条件下沙漠腹地绿洲优势种胡杨和柽柳叶片δ¹³C值,分析了胡杨和柽柳的水分利用效率对不同地下水埋深的响应。结果表明: 随着地下水埋深由2.1 m增加到4.3 m,柽柳叶片的δ¹³C值先略有增加后处于较为稳定状态,柽柳采取较为稳定的水分利用效率适应干旱环境;胡杨叶片的δ¹³C值呈现先略有减小后增加的趋势,胡杨通过提高水分利用效率的策略适应干旱胁迫。同一地下水埋深条件下柽柳叶片的δ¹³C值高于胡杨叶片,表明柽柳的水分利用效率高于胡杨。     

心理应激对小鼠脂肪组织黄嘌呤氧化酶表达、活性及相关指标的影响*

目的:探讨心理应激对小鼠脂肪组织黄嘌呤氧化酶表达、活性及相关指标的作用。方法:雄性无特定病原体(SPF)级20只昆明小鼠随机分2组(每组10只),即慢性束缚应激(Stress)组和正常对照(Control)组。Stress组小鼠每天在自制式束缚器中限制活动2 h,其余时间两组小鼠在相同环境中自由饮水摄食,实验持续14 d,取血和白色脂肪组织(WAT);观察脂肪组织病理学改变,检测WAT中黄嘌呤氧化酶(XO)和烟酰胺腺嘌呤二核苷酸磷酸氧化酶4(Nox-4)的蛋白水平,检测WAT组织中XO、Nox-4、超氧化物歧化酶(Mn SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)、脂联素(ADPN)、单核细胞趋化蛋白1(MCP-1)、白介素6(IL-6)、肿瘤坏死因子α(TNF-α)、胰岛素受体底物1(IRS-1)、葡萄糖转运蛋白4(GLUT-4)、组织因子(TF)、纤溶酶原激活物抑制物1(PAI-1)的mRNA表达,检测血清和WAT组织中XO酶活性以及血清甘油三酯(TG)、总胆固醇(T-Cho)、游离脂肪酸(FFA)、尿酸(UA)的含量。结果:与control组比较,stress小鼠腹股沟WAT组织中XO免疫染色阳性着色细胞黄褐色沉淀深且丰富,WAT中出现大量的单核细胞、中性粒细胞、嗜酸性粒细胞及浆细胞浸润反应和炎症性的改变;血清XO浓度、WAT组织中XO mRNA水平和XO的酶活性显著升高(P＜0.01),血清游离脂肪酸(FFA)和尿酸(UA)的含量显著增高(P＜0.01),WAT组织中Nox-4蛋白、MCP-1、IL-6、TNF-α、TF、PAI-1mRNA的表达水平显著增高(P＜0.01),而Mn-SOD、GSH-Px、CAT、ADPN、IRS-1和GLUT-4的mRNA水平则显著降低(P＜0.01)。结论:心理应激可诱发脂肪XO过量表达及其活性增高,进而引起脂肪炎症、糖代谢及凝血酶原异常等反应。     

塔克拉玛干沙漠腹地柽柳年轮宽度对地下水埋深的响应

【目的】柽柳作为干旱荒漠生态系统的典型物种,研究其年轮宽度对地下水响应的保护有重要价值。【方法】研究基于沙漠腹地达理雅博依绿洲地下水埋深资料,利用年轮测定方法分析不同地下水埋深状况下柽柳年轮宽度的变化,探讨其与地下水埋深变化的关系。【结果】样地一地下水埋深随时间逐年增加,埋深范围是1.2～2.6 m,柽柳的年轮宽度在2001-2020年呈显著增加趋势,变化范围为0.98～5.80 mm,年轮宽度年际间差异显著;样地二地下水埋深随时间增长呈现先增加后减小的趋势,埋深范围是2.7～4.5 m,柽柳年轮宽度在1977-2020年整体呈正弦函数变化,范围为1.46～4.41 mm,年轮宽度年际间差异性不显著;样地一柽柳标准年表振幅范围是0.502～1.641,大于样地二柽柳标准年表振幅范围为0.577～1.331。【结论】样地一地下水埋深向着柽柳生长适宜的范围增加时,有利于柽柳的生长,表现为年轮宽度增加,样地二的柽柳年轮宽度变化和地下水埋深之间无显著相关性。     

Indoxyl Sulfate-Induced Activation of (Pro)renin Receptor Promotes Cell Proliferation and Tissue Factor Expression in Vascular Smooth Muscle Cells

Chronic kidney disease (CKD) is associated with an increased risk of cardiovascular disease (CVD). (Pro)renin receptor (PRR) is activated in the kidney of CKD. The present study aimed to determine the role of indoxyl sulfate (IS), a uremic toxin, in PRR activation in rat aorta and human aortic smooth muscle cells (HASMCs). We examined the expression of PRR and renin/prorenin in rat aorta using immunohistochemistry. Both CKD rats and IS-administrated rats showed elevated expression of PRR and renin/prorenin in aorta compared with normal rats. IS upregulated the expression of PRR and prorenin in HASMCs. N-acetylcysteine, an antioxidant, and diphenyleneiodonium, an inhibitor of nicotinamide adenine dinucleotide phosphate oxidase, suppressed IS-induced expression of PRR and prorenin in HASMCs. Knock down of organic anion transporter 3 (OAT3), aryl hydrocarbon receptor (AhR) and nuclear factor-κB p65 (NF-κB p65) with small interfering RNAs inhibited IS-induced expression of PRR and prorenin in HASMCs. Knock down of PRR inhibited cell proliferation and tissue factor expression induced by not only prorenin but also IS in HASMCs.

Conclusion

IS stimulates aortic expression of PRR and renin/prorenin through OAT3-mediated uptake, production of reactive oxygen species, and activation of AhR and NF-κB p65 in vascular smooth muscle cells. IS-induced activation of PRR promotes cell proliferation and tissue factor expression in vascular smooth muscle cells.     

早春不稳定传粉环境中新疆郁金香混合交配系统中的自交策略

【目的】在植物的所有生活史特征中,交配格局可能是对宏观进化影响最大的因素。在不确定的传粉环境中,两性花植物常常具有潜在的自交能力,鉴于自交的交配代价,两种交配方式如何权衡,一直是深入理解交配系统演化的关键问题。【方法】为了探讨早春不稳定传粉环境中植物的自交策略,以早春短命植物新疆郁金香为研究对象,通过野外观测及人工控制实验对自然居群的开花习性、传粉者类群、散粉动态、自花粉传递模式和交配系统等进行研究。【结果】（1）新疆郁金香自然种群4月上旬或中旬开花,单花期5-6 d,白天开放晚上闭合,花粉的释放从外轮开始,由下到上呈拉链式次序呈现。（2）传粉者主要为蜂类和食蚜蝇,访花频率普遍较低,且在年份间存在较大差异,但结实率普遍较高。（3）控制授粉实验表明居群为异交为主,部分自交亲和的混合性交配系统类型。傍晚花闭合时雄蕊的自主运动促进了柱头的自花授粉,这一传粉模式促进了竞自交的发生,但大量自花粉的落置发生在开花后的第4 d,占自花粉总落置量的50.22%,为一种延迟自交的机制。【结论】在传粉受限的情况下,新疆郁金香的竞自交和延迟自交促进了柱头的花粉落置,这种集异交、竞自交和延迟自交为一体的交配策略灵活地应对了早春不稳定的传粉环境,是对早春低温度条件下不确定传粉服务的一种适应,也是早春短命植物的一种繁殖保证对策。     

The Volatile Oil of Nardostachyos Radix et Rhizoma Induces Endothelial Nitric Oxide Synthase Activity in HUVEC Cells

Nardostahyos Radix et Rhizoma (NRR; the root and rhizome of Nardostachys jatamansi DC.) is a widely used medicinal herb. Historically, NRR is being used for the treatment of cardiovascular and neurological diseases. To search for active ingredients of NRR, we investigated the vascular benefit of NRR volatile oil in (i) the vasodilation in rat aorta ring, and (ii) the release of nitric oxide (NO) and the phosphorylation of endothelial NO synthase (eNOS) in cultured human umbilical vein endothelial cells (HUVECs). By measuring the fluorescence signal in cultures, application of NRR volatile oil resulted in a rapid activation of NO release as well as the phosphorylation of eNOS: both inductions were markedly reduced by L-NAME. In parallel, the phosphorylation level of Akt kinase was markedly increased by the oil treatment, which was partially attenuated by PI3K/Akt inhibitor {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002. This inhibitor also blocked the NRR-induced NO production and eNOS phosphorylation. In HUVECs, application of NRR volatile oil elevated the intracellular Ca²⁺ level, and BAPTA-AM, a Ca²⁺ chelator, reduced the Ca²⁺ surge: the blockage were also applied to NRR-induced eNOS phosphorylation and NO production. These findings suggested the volatile oil of NRR was the major ingredient in triggering the vascular dilatation, and which was mediated via the NO production.     

Molecular mechanism of RNase R substrate sensitivity for RNA ribose methylation

RNA 2′-O-methylation is widely distributed and plays important roles in various cellular processes. Mycoplasma genitalium RNase R (MgR), a prokaryotic member of the RNase II/RNB family, is a 3′-5′ exoribonuclease and is particularly sensitive to RNA 2′-O-methylation. However, how RNase R interacts with various RNA species and exhibits remarkable sensitivity to substrate 2′-O-methyl modifications remains elusive. Here we report high-resolution crystal structures of MgR in apo form and in complex with various RNA substrates. The structural data together with extensive biochemical analysis quantitively illustrate MgR’s ribonuclease activity and significant sensitivity to RNA 2′-O-methylation. Comparison to its related homologs reveals an exquisite mechanism for the recognition and degradation of RNA substrates. Through structural and mutagenesis studies, we identified proline 277 to be responsible for the significant sensitivity of MgR to RNA 2′-O-methylation within the RNase II/RNB family. We also generated several MgR variants with modulated activities. Our work provides a mechanistic understanding of MgR activity that can be harnessed as a powerful RNA analytical tool that will open up a new venue for RNA 2′-O-methylations research in biological and clinical samples.