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1.
杨玉帅  李泽  金天明  杨升 《畜牧兽医学报》2021,52(10):2924-2933
旨在提高烯丙孕素原药在水中的溶解度,提高烯丙孕素原药的生物利用度,使用磺丁基-β-环糊精对烯丙孕素原药进行包合。本试验使用冷冻干燥法来制备烯丙孕素-磺丁基-β-环糊精包合物,以此来解决烯丙孕素在临床使用中因其水不溶性而受到限制及其使用后生物利用度低的问题,进而拓宽烯丙孕素的药用途径。通过傅里叶变换红外光谱法、热重分析法和显微镜成像法对所制得的烯丙孕素包合物进行表征,并用溶解度法对包合物进行溶解度测定。以包合物的收率和包合率为评价指标,筛选最优的包合物制备条件。结果显示:经筛选,包合物的最佳制备条件:在55℃,ALT与SBE-β-CD的投料摩尔比为1:6,包合时间为5 h,溶液pH为8,溶剂量为15 mL(当以ALT投药量为0.1 g时计);以最优制备条件制备所得的包合物中ALT的平均包合率为(90.90±1.80)%(n=3),平均载药量为(4.30±2.30)%(n=3),包合物的收率为(93.19±1.67)%。经傅里叶变换红外光谱法、热重分析法和显微镜成像法对所制得的包合物进行表征,可证实成功制得包合物。溶解度法试验结果表明,形成包合物后,其溶解度较烯丙孕素原药提高了988.86倍,且该包合物稳定性好,可满足不同剂型的要求。磺丁基-β-环糊精对烯丙孕素原药具有较好的增溶作用,达到了增加药物溶解度的目的,且该制备方法简单,条件温和,易于产业化生产,有利于烯丙孕素的进一步开发利用。  相似文献   
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Processes of soil organic matter (SOM) stabilization and the reverse, destabilization of SOM resulting in subsequent release and mobilization of nutrients from SOM, remain largely unresolved. The perception of SOM as supramolecular aggregates built of low molecular mass biomolecules is currently emerging. Polyvalent metal cations contribute to SOM tertiary structure by bridging functional groups of such molecules (Simpson et al., 2002). The strong bond to metals protects high quality organic material from being immediately accessed and decomposed. Here we propose a three-step process by which low molecular mass organic acids (LMMOAs) and hydrolytic enzymes act in series to destabilize SOM supramolecules to release organic nitrogen (N) and phosphorus (P) for local hyphal and root uptake. Complexation of the stabilizing metals by fungal-released LMMOA gives fungal-root consortia direct access to organic substrates of good quality. Because of their small sizes and carboxyl group configuration, citric and oxalic acids are the most effective LMMOAs forming stable complexes with the main SOM bridging metals Ca and Al in SOM. Citrate, forming particularly strong complexes with the trivalent cations Al and Fe, is dominant in soil solutions of low-productive highly acidic boreal forest soils where mycorrhizal associations with roots are formed predominantly by fungi with hydrophobic hyphal surfaces. In these systems mycelia participate in the formation of N-containing SOM with a significant contribution from strong Al bridges. In less acidic soils of temperate forests, including calcareous influenced soils, SOM is stabilized predominantly by Ca bridges. In such systems mycorrhizal fungi with more hydrophilic surfaces dominate, and oxalic acid, forming strong bidentate complexes with Ca, is the most common LMMOA exuded. A plant-fungus driven biotic mechanism at the supramolecular aggregate level (103–105 Da) resolves micro-spatial priming of SOM, where the destabilization step is prerequisite for subsequent release of nutrients.  相似文献   
4.
A method for fractionating sorghum proteins using extraction solvents and techniques designed to obtain polymeric protein structures (especially disulfide linked) was developed. Extraction and separation conditions were optimized in terms of completeness of protein extraction, sample stability, and analytical resolution. After pre-extraction of albumins and globulins, a 3-step sequential procedure involving no reducing agents was applied to ground whole sorghum flour. The three fractions obtained represented proportionally different protein polymer contents and molecular weight distribution as evidenced by comparative size exclusion chromatography. Protein composition also varied among the extracts with differences in kafirin composition and non-kafirin proteins detected in the fractions by RP-HPLC and SDS-PAGE analysis. The ability to quantify and further characterize sorghum polymeric protein complexes will be useful for additional studies linking protein structures with functionality and digestibility and variations for these properties within diverse sorghum germplasm.  相似文献   
5.
In vivo, resumption of oocyte meiosis occurs in large ovarian follicles after the preovulatory surge of luteinizing hormone (LH). The LH surge leads to the activation of a broad signaling network in mural granulosa cells equipped with LH receptors. The signals generated in the mural granulosa cells are further augmented by locally produced peptides or steroids and transferred to the cumulus cell compartment and the oocyte itself. Over the last decade, essential progress has been made in the identification of molecular events associated with the final maturation and ovulation of mammalian oocytes. All new evidence argues for a multiple roles of mitogen-activated protein kinase 3/1 (MAPK3/1) in the gonadotropin-induced ovulation processes. However, the knowledge of gonadotropin-induced signaling pathways leading to MAPK3/1 activation in follicular cells seems limited. To date, only the LH-induced transactivation of the epidermal growth factor receptor/MAPK3/1 pathway has been described in granulosa/cumulus cells even though other mechanisms of MAPK3/1 activation have been detected in other types of cells. In this review, we aimed to summarize recent advances in the elucidation of gonadotropin-induced mechanisms leading to the activation of MAPK3/1 in preovulatory follicles and cultured cumulus-oocyte complexes and to point out a specific role of this kinase in the processes accompanying final maturation of the mammalian oocyte.  相似文献   
6.
The aim of this review is to describe the main physicochemical characteristics of diverse types of humic‐metal‐phosphate acid complexes. The effects of these complexes on phosphorus (P) fixation in soils with different pH values and physicochemical features and on plant phosphorus uptake are also discussed. Humic‐metal‐phosphate complexes have apparent stability constants in the same range as those of metal‐humic complexes, in solutions with diverse pH and ionic‐strength values. Likewise, the molecular‐size distribution of humic‐metal‐phosphate complexes as a function of pH is similar to that of potassium or sodium humates and metal‐humic complexes. Humic‐metal‐phosphate complexes are able to decrease phosphate fixation in soils and increase plant growth and phosphate uptake. Phosphorus fertilizers containing humic‐metal‐phosphate complexes proved to be efficient to improve plant growth and P uptake with respect to conventional fertilizers such as single superphosphate. The values of parameters related to plant phosphorus‐utilization efficiency (PUt E) suggest that the regulation of root acquisition of phosphate from these complexes could involve the interregulation of a system for the optimization of metabolic P utilization in the shoot and another system involving stress responses of roots under phosphorus deficiency.  相似文献   
7.
主要从不同种子种壳、种皮的结构,种皮的透水性、透气性,种胚发育结构、形态,种子内含物成分的休眠机制进行综述,找到较好的实验方法研究种子的休眠机理,从不同的角度剖析种子休眠。  相似文献   
8.
制备一种新型钌配合物[Ru(MeI m)_4(4mopip)]~(2+)(RuM e Mo),运用元素分析(C、H、N)、电喷雾电离质谱(ESI-MS)、核磁共振谱(~1H NMR)对Ru Me Mo进行了结构表征。紫外光谱、热变性试验和圆二色光谱研究RuM e Mo与F21T的分子作用机制,发现其能诱导线性G-四链体DNA形成混合型结构并能有效稳定G-四链体。MTT法评估RuM e Mo对癌细胞的抑制作用及其对正常细胞的毒性,发现其对肺癌细胞(A549)表现出高选择的抑制作用,而对正常人类肺原胚细胞(CDDP)则表现出较低的细胞毒性。本研究结果表明,RuM e Mo因其稳定G-四链体DNA的能力,从而有被运用于肺癌治疗的潜质。  相似文献   
9.
罗勇  魏国清  杨云  张秉君  王萃娟 《安徽农业科学》2011,39(27):16650-16652
[目的]以双[3-(4-吡啶)吡唑基]-对二甲苯(bipppx)为配体与锌(Ⅱ)、镉(Ⅱ)、铜(Ⅱ)、钴(Ⅱ)的4种金属盐进行反应合成4种配合物,并对其进行抑菌活性研究。[方法]将配体bipppx溶于无水乙醇中,分别加入硝酸锌、乙酸镉、乙酸铜、乙酸钴,加热回流,过滤干燥得目标化合物;运用紫外光谱分析其配位情况;采用纸片法对其进行抑菌活性研究。[结果]抑菌活性试验结果表明,配体及配合物对大肠杆菌、产气杆菌的抑菌性较为明显,对金黄色葡萄球菌无明显抑菌作用,并且以bipppx-Co(Ⅱ)配合物的抑菌活性最佳。[结论]bipp-px金属配合物的制备为配位化学增添新的内容,良好的抑菌活性为其在农业、医药上的应用提供了依据。  相似文献   
10.
利用锡林郭勒草原2006年TM遥感影像数据,结合野外调查,在ArcGIS软件的支持下,将研究区面积大于5km2的湖泊-湿地复合体划分为湖泊、沼泽水体、裸地、裸滩与盐化地、湖滩湿地、典型湿地、地带性草原7种土地利用/覆盖类型,揭示不同草原地带湖泊-湿地复合体的结构变化规律。结果表明:在整个锡林郭勒草原范围内,湖泊相对集中...  相似文献   
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