驳枝和施氮对早花烤烟成熟期水溶性总糖和淀粉含量的影响

在大田条件下,研究驳枝和追施氮肥对早花烤烟成熟期叶片中水溶性总糖和淀粉含量的影响。结果表明：高施氮量抑制烟草叶片的水溶性总糖和淀粉积累,然而低氮促进了中部叶水溶性总糖和淀粉积累。     

Panax notoginseng saponins suppress oxygen-glucose deprivation/reoxygenation-induced pyroptosis of SH-SY5Y cells

AIM To investigate the effect of Panax notoginseng saponins (PNS) on pyroptosis of SH-SY5Y cells induced by oxygen-glucose deprivation/reoxygenation (OGD/R). METHODS The OGD/R was conducted to induce ischemia/reperfusion injury in SH-SY5Y cells. The effects of PNS on the viability (detected by CCK-8 assay) and membrane permeability [indicated by lactate dehydrogenase (LDH) leakage and propidium iodide (PI) staining positive cell proportion] of OGD/R-induced SH-SY5Y cells were observed. The protein levels of gasdermin D (GSDMD), GSDMD N-terminal fragment (GSDMD-N), caspase-1 and caspase-4, and the release of interleukin-1β (IL-1β) and IL-18 in the cells were also determined. RESULTS After exposure to OGD/R, the viability of SH-SY5Y cells dramatically decreased (P<0.01), while the LDH leakage, the PI staining positive cell proportion, the protein levels of GSDMD, GSDMD-N, caspase-1 and caspase-4, and the release of IL-1β and IL-18 were significantly increased (P<0.01). However, PNS treatment enhanced the viability of SH-SY5Y cells inhibited by OGD/R (P<0.01), but reduced the leakage of LDH and the percentage of PI staining positive cells (P<0.05 or P<0.01). Moreover, PNS reversed the increases in the protein levels of GSDMD, GSDMD-N, caspase-1 and caspase-4 and the release of IL-1β and IL-18 in OGD/R-induced SH-SY5Y cells (P<0.05 or P<0.01). CONCLUSION Treatment with PNS alleviates OGD/R-induced injury in SH-SY5Y cells. Its mechanism may be related to inhibition of SH-SY5Y cell pyroptosis induced by OGD/R.     

紫花苜蓿MsSQE1的克隆及对皂甙合成的功能分析

【目的】鲨烯环氧酶（squalene epoxidases,SQE）是苜蓿皂甙合成途径中的一种限速酶,与苜蓿皂甙的合成密切相关。通过对苜蓿鲨烯环氧酶（MsSQE1）基因的克隆及在苜蓿中过表达,探究鲨烯环氧酶对皂甙合成的作用机制。【方法】以模式植物蒺藜苜蓿鲨烯环氧酶基因序列设计引物,同源克隆苜蓿MsSQE1。对MsSQE1进行生物信息学分析;通过基因枪轰击技术,使MsSQE1在洋葱表皮瞬时表达,进行亚细胞定位。利用qRT-PCR方法分析该基因在根、茎、叶中的表达水平,以及在紫外辐射、ABA和GA₃条件下的表达模式。在茉莉酸甲酯（MeJA）的诱导下,分析MsSQE1的转录水平,及对苜蓿皂甙含量的影响。利用根癌农杆菌转化体系,获得过表达MsSQE1的阳性转基因植株,并测定转基因植株的皂甙含量。【结果】克隆了MsSQE1的cDNA序列,开放阅读框1 578 bp,编码525个氨基酸,等电点为8.59。同源性比对分析,其氨基酸序列与蒺藜苜蓿中SQE1氨基酸序列同源性为98.6%,与拟南芥的同源性为80%。亚细胞定位显示,MsSQE1可能定位于细胞膜。组织特异性表达分析显示,MsSQE1在叶中的表达量最高,茎中次之,根中的表达量最低。在紫外辐射、ABA和GA₃的诱导表达显示,紫外辐射诱导24 h,叶中表达量最高; GA₃（50 μmol·L ^-1）和 ABA（100 μmol·L ^-1）处理,均为8 h叶中表达量最高;MeJA处理能诱导MsSQE1表达量上调的同时苜蓿总皂甙含量也随着MsSQE1表达的上调而增加。分析过表达MsSQE1转基因苜蓿和转空载体苜蓿株系发现,MsSQE1的表达水平和总皂甙含量均升高,其中MsSQE1的表达水平是对照的3.11—9.45倍,总皂甙含量比对照提高14.26%—28.05%,暗示MsSQE1是苜蓿皂甙合成途径中的一种关键调节酶。【结论】从豆科牧草紫花苜蓿中克隆了MsSQE1并进行功能分析。在苜蓿中过表达MsSQE1能增加苜蓿总皂甙含量,暗示MsSQE1的表达影响苜蓿皂甙的生物合成,可能对皂甙的合成有重要的调节作用。     

苜蓿生物活性物质在动物上的应用

苜蓿中含有许多生物活性物质,能够显著影响动物的生长性能、繁殖机能和免疫功能,有些活性物质还可以作为人的保健品使用。本文主要介绍苜蓿皂苷、苜蓿多糖、苜蓿黄酮的生物学功能以及国内外学者对苜蓿中活性成分研究的最新成果。苜蓿中活性物质可以作为动物的饲料添加剂使用,一定剂量的苜蓿活性物质可以提高动物体内的淋巴细胞水平,增加免疫力;提高谷胱甘肽过氧化物酶的活性,抑制丙二醛的水平,具有抗氧化功能;增加动物的生产性能和繁殖性能。     

Seasonal and Diurnal Variation in Water-Soluble Carbohydrate Concentrations of Repeatedly Defoliated Red and White Clovers in Central Kentucky

Nonstructural carbohydrates of pasture plants, comprising water-soluble carbohydrates (WSCs) and starch, may contribute to excessive consumption of rapidly fermentable carbohydrates by grazing horses. Seasonal and diurnal variation in WSCs were studied in red (Trifolium pratense L.) and white clovers (Trifolium repens L.) subjected to a typical management regime of rotationally grazed horse pastures. Two red and two white clover cultivars from monoculture plots were harvested after 4 weeks of growth from April to October of 2015, in the morning and afternoon of each harvest date. Water-soluble carbohydrates were quantified for each harvest, and starch was quantified for two harvests. Mean monthly WSC concentrations ranged from 80 to 99 mg/g (freeze-dried weight basis), whereas mean starch concentrations were 31 and 40 mg/g. In September, white clover had 14% more WSCs than red clover (P < .0001). Water-soluble carbohydrate concentrations were 10% higher in the afternoon than in the morning (P < .0001). Starch concentrations were 290% higher in the afternoon than in the morning (P < .0001), and nonstructural carbohydrate concentrations in the afternoon averaged 150 mg/g. Further studies are needed to determine whether the mixed grass-legume pastures of central Kentucky accumulate enough nonstructural carbohydrates to present risk factors for equine metabolic or digestive dysfunction.     

生物炭表面水溶活性分子可以有效提高水稻的耐旱性

生物炭是一种可以改良土壤、增强作物产量和提升作物品质的新型农林废弃物再利用材料。本研究通过振荡方式制备生物炭浸提液,利用水培系统培养水稻幼苗,以20%PEG6000、300 mmol/L和500 mmol/L甘露醇模拟干旱胁迫,研究生物炭表面水溶活性分子对水稻幼苗抗旱性的影响。研究结果发现:生物炭浸提液可有效缓解干旱胁迫造成的水稻种子萌发和幼苗生长抑制,缓解叶绿素含量、鲜重及存活率的降低,同时可以降低体内的活性氧积累等。实时定量RT-PCR检测表明生物炭浸提液促进干旱胁迫响应标志基因的表达量。研究结果说明生物炭浸提液可以提高干旱胁迫下水稻幼苗的抗氧化能力,进一步提高水稻幼苗对干旱胁迫的耐受性。     

海参皂苷的研究现状

海洋中蕴涵着丰富的天然资源,海参作为一种食品和药材,具有很高的保健功能和药用价值。海参皂苷是海参体内的一种次生代谢产物,具有广泛的生理药理活性,因此潜藏了极大的应用价值。本文就近年来国内外关于海参皂苷性质的研究状况做一些简要的概述,为进一步研究海参皂苷提供较为详尽的参考资料。     

计算机软件模拟α-乳白蛋白与皂苷的分子对接

皂苷小分子具有很强的生理活性,在人体中必须与靶细胞生物大分子相互作用才能发挥其生物作用。α-乳 白蛋白（α-lactalbumin,α-LA）是球状蛋白质,能结合疏水配体,在食品工业作为功能性配料。采用计算机模拟的 方法,对2 类皂苷（达玛烷型皂苷和齐墩果型皂苷）和α-LA相互作用进行研究,并获得其相互作用模式的相关图 像。分子对接结果表明,2 种类型的皂苷与α-LA活性口袋内的氨基酸残基均以疏水相互作用及氢键作用结合,但达 玛烷型皂苷结构更复杂,可以提供更多结合位点,且其形成氢键的作用力更强。     

Three new water-soluble alkaloids from the leaves of Suregada glomerulata (Blume) Baill

Three new water-soluble alkaloids (1-3) together with twelve known compounds (4-15) have been isolated from the water extract of leaves of Suregada glomerulata. Their structures were determined by spectroscopic analysis and chemical method. Compounds 1-3 were evaluated for their in vitro inhibitory activity against α-glucosidase and HIV-1 replication. However, no significant activities were found.     

New furostanol saponins from Smilax aspera L. and their in vitro cytotoxicity

The occurrence of the two new cis-fused A/B rings furostanol saponins (25S)-26-O-β-d-glucopyranosyl-5β-furostan-1β,3β,22α,26-tetraol-1-O-β-d-glucopyranoside and (25S)-26-O-β-d-glucopyranosyl-5β-furostan-1β,2β,3β,5β,22α,26-hexaol and the known compounds (25S)-26-O-β-d-glucopyranosyl-5β-furostan-3β,22α,26-triol-3-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-glucopyranosyl-(1→2)-O-β-d-glucopyranoside and (25S)-26-O-β-d-glucopyranosyl-5β-furostan-3β,22α,26-triol-3-O-β-d-glucopyranosyl-(1→2)-O-β-d-glucopyranoside, trans-resveratrol, (+) catechin and (−) epicatechin in the rhizomes of Smilax aspera is reported. All saponins have been isolated as their 22-OMe derivatives, which were further subjected to extensive spectroscopic analysis. The isolated furostanol saponins were evaluated for cytotoxic activity against human normal amniotic and human lung carcinoma cell lines using neutral red and MTT assays. In vitro experiments showed significant cytotoxicity in a dose dependent manner with IC₅₀ values in the range of 32.98-94.53 µM.