羊栖菜组分多糖对α-葡萄糖苷酶的抑制作用

为高效利用羊栖菜组分多糖(SFPSⅠ),以SFPSⅠ为原料,α-葡萄糖苷酶作为靶标,研究SFPSⅠ对α-葡萄糖苷酶的抑制作用及其结构的影响,建立具有α-葡萄糖苷酶活性的Caco-2细胞模型,并对Caco-2细胞模型上α-葡萄糖苷酶活性的抑制效果进行研究。结果表明,SFPSⅠ对α-葡萄糖苷酶有明显的抑制作用,使得α-葡萄糖苷酶活力下降一半时的抑制剂浓度,即半抑制(IC₅₀)为0.31 mg·mL^-1。SFPSⅠ对α-葡萄糖苷酶的抑制作用是一个可逆过程,抑制类型为混合型抑制。动力学分析结果表明,SFPSⅠ对α-葡萄糖苷酶的抑制常数(K_i)为0.143μmol·L^-1。荧光测定结果表明,SFPSⅠ结合会引起α-葡萄糖苷酶三级结构的明显变化。随着SFPSⅠ浓度的升高,其对Caco-2细胞模型上α-葡萄糖苷酶抑制效果越好。本研究结果为进一步探讨和设计新型α-葡萄糖苷酶抑制剂奠定了科学基础,同时也为开发具有降血糖功能的功能性药品与保健品提供了新资源。     

羊栖菜组分多糖对α-葡萄糖苷酶的抑制作用

为高效利用羊栖菜组分多糖(SFPSⅠ),以SFPSⅠ为原料,α-葡萄糖苷酶作为靶标,研究SFPSⅠ对α-葡萄糖苷酶的抑制作用及其结构的影响,建立具有α-葡萄糖苷酶活性的Caco-2细胞模型,并对Caco-2细胞模型上α-葡萄糖苷酶活性的抑制效果进行研究。结果表明,SFPSⅠ对α-葡萄糖苷酶有明显的抑制作用,使得α-葡萄糖苷酶活力下降一半时的抑制剂浓度,即半抑制(IC₅₀)为0.31 mg·mL^-1。SFPSⅠ对α-葡萄糖苷酶的抑制作用是一个可逆过程,抑制类型为混合型抑制。动力学分析结果表明,SFPSⅠ对α-葡萄糖苷酶的抑制常数(K_i)为0.143 μmol·L^-1。荧光测定结果表明,SFPSⅠ结合会引起α-葡萄糖苷酶三级结构的明显变化。随着SFPSⅠ浓度的升高,其对Caco-2细胞模型上α-葡萄糖苷酶抑制效果越好。本研究结果为进一步探讨和设计新型α-葡萄糖苷酶抑制剂奠定了科学基础,同时也为开发具有降血糖功能的功能性药品与保健品提供了新资源。     

新型甘蔗剥叶机仿真与试验研究

设计了一种新型的甘蔗收获机剥叶系统,通过三维设计软件Pro/E建立了甘蔗收获机剥叶系统虚拟样机模型,并导入多体动力学仿真软件ADAMS中进行了关键碎叶机构各个参数优化仿真实验。仿真与物理样机试验表明:在第1级喂入机构保证甘蔗一定工作初速度与第3级辅助剥叶机构对残余蔗叶进行清理的前提下,当此碎叶机构碎叶对辊转速为750r/min、碎叶元件交错深度为10cm、交错角度30°时,该剥叶系统能满足设计要求且可高效完成剥叶工作。     

Porcine pluripotent stem cells: progress,challenges and prospects

Pluripotent stem cells (PSCs) are characterized by their capacity for high self-renewal and multiple differentiation potential and include embryonic stem cells, embryonic germ cells and induced PSCs. PSCs provide a very suitable model for the studies of human diseases, drugs screening, regenerative medicine and developmental biology research. Pigs are considered as an ideal model for preclinical development of human xenotransplantation, therapeutic approaches and regenerative medicine because of their size and physiological similarity to humans. However, lack of knowledge about the derivation, characterization and pluripotency mechanisms of porcine PSCs hinders progress in these biotechnologies. In this review, we discuss the latest progress on porcine PSCs generation, evaluation criteria for pluripotency, the scientific and technical questions arising from these studies. We also introduce our perspectives on porcine PSC research, in the hope of providing new ideas for generating naive porcine PSCs and animal breeding.     

刈割对元谋干热河谷区海狮苏丹草生长及生产性能的影响

以牧草鲜草产量、再生速度、分蘖数等为观测指标．研究不同刈割处理和刈割茬数对元谋干热河谷区海狮苏丹草[Sorghumsudolbense（Hayking）Stapf．]生长及生产性能的影响。研究结果表明：海狮苏丹草在干热河谷区具有较好的适应性,在其生长季内可刈割5次：留茬高度和茬数对其再生性能和分蘖能力均有显著影响．其中刈割茬数对其再生速度和分蘖数影响最大,随着刈割茬数增加再生速度显著减慢而分蘖数则明显增加;海狮苏丹草不同留茬高度、刈割茬数对生物量均存在显著差异：就生物量和再生能力来看．海狮苏丹草留茬高度以10cm为宜,其平均再生速度达2．50cm／d,鲜草产量可达125．76t／hm2．同时在10cm留茬高度下各茬问生物量变化较为稳定．持续生长能力较强。     

湖南油茶GIS精细化气候区划研究

油茶是湖南重要的经济作物之一,为了探讨油茶气候适宜种植区域,为油茶布局提供科学依据。笔者根据油茶生长发育对气象条件的要求,以年平均气温、年日照时数及盛花期降水量3个指标作为油茶气候区划因子,针对不同气象要素采用不同的数理统计方法进行500 m×500m小网格插值,对插值后小网格的气象数据和气候区划采用等级划分法,进行湖南油茶进行精细化气候区划。结果表明：湖南绝大部分地方为油茶生长的气候最适宜区,仅洞庭湖部分地方为油茶生长的欠适宜或不适宜区;且随着近年湖南气候变暖,油茶最适宜区有所增加,发展潜力大。     

中卫市沙坡头区硒砂瓜施肥试验

试验在宁夏中卫市环香山地区压砂3年,5年,8年的砂田上,施用不同品种有机无机复合肥料进行硒砂瓜种植试验.结果表明,在砂田上施用生物有机无机复合肥能显著提高硒砂瓜的产量,且以"玉泉"生物有机无机复合肥每666.7 m2用量80~100 kg为最佳.     

茶叶腌制过程中亚硝酸盐和游离氨基酸含量的动态变化分析

本实验以绿毛茶为原料进行腌制,分别对其安全性指标--亚硝酸盐含量,营养风味指标--游离氨基酸含量进行动态研究,结果发现:在3个月的腌制期间,亚硝酸盐与游离氨基酸的动态含量变化呈现相反的变化趋势;亚硝酸盐含量变化呈两度下降两度上升的总体下降趋势;游离氨基酸的含量呈三度上升三度下降的总体上升趋势.茶叶腌制后,并没有呈现一般果蔬类制品在腌制前期,亚硝酸盐含量快速上升的现象,却呈现亚硝酸盐含量总体下降的变化趋势,且远低于蔬菜<4 mg/g,酱腌菜<20 mg/g的国家安全控制标准.而游离氨基酸含量与果蔬腌制品一样呈现总体上扬的变化趋势.     

Occurrence, Distribution, and Polymerase Chain Reaction-Based Detection of Resistance to Sterol Demethylation Inhibitor Fungicides in Populations of Blumeriella jaapii in Michigan

ABSTRACT The intensive use of site-specific fungicides in agricultural production provides a potent selective mechanism for increasing the frequency of fungicide-resistant isolates in pathogen populations. Practical resistance occurs when the frequency and levels of resistance are great enough to limit the effectiveness of disease control in the field. Cherry leaf spot (CLS), caused by the fungus Blumeriella jaapii, is a major disease of cherry trees in the Great Lakes region. The site-specific sterol demethylation inhibitor fungicides (DMIs) have been used extensively in the region. In 2002, CLS control failed in a Michigan orchard that had used the DMI fenbuconazole exclusively for 8 years. That control failure and our observations from around the state suggested that practical resistance had developed in B. jaapii. Field trial data covering 1989 to 2005 for the DMIs fenbuconazole and tebuconazole supported observations of reduced efficacy of DMIs for controlling CLS. To verify the occurrence of fungicide-resistant B. jaapii, monoconidial isolates were collected in two surveys and tested using a fungicide-amended medium. In one survey, 137 isolates from sites with different DMI histories (no known history, mixed or alternated with other fungicides, and exclusive use) were tested against 12 concentrations of fenbuconazole, tebuconazole, myclobutanil, and fenarimol. Isolates from sites with no prior DMI use were DMI sensitive (DMI(S) = no colony growth at 0.2 mug/ml a.i.) whereas the isolates from the site with prior exclusive use showed growth at DMI concentrations 3 to >100 times higher, and were rated as DMI resistant (DMI(R)). A second survey examined 1,530 monoconidial isolates, including 1,143 from 62 orchard sites in Michigan, where DMIs had been used to control CLS. Resistance to fenbuconazole was detected in 99.7% of the orchard isolates. All isolates from wild cherry trees were sensitive and isolates from feral and dooryard trees showed a range of sensitivities. A polymerase chain reaction (PCR)-based detection method for identifying B. jaapii and DMI(R) was developed and tested. The species-specific primer pair (Bj-F and Bj-R) based on introns in the CYP51 gene of B. jaapii, and the DMI(R)-specific primer pair (DMI-R-Bj-F and DMI-R-Bj-R) based on an insert found upstream of CYP51 in all DMI(R) isolates, provided an accurate and rapid method for detecting DMI(R) B. jaapii. The PCR-based identification method will facilitate timely decision making and continued monitoring of DMI(R) subpopulations in response to management programs.     

采棉机智能监控系统CAN应用层协议设计

以4MZ-6A型六行采棉机为应用对象,搭建了基于CAN总线的数字化智能监控系统。以CAN2.0B协议帧结构为基础,解析扩展帧ID报文标识符的组成和含义,研究了基于CAN总线应用层协议的制定原则、方法及其实现。该协议在六行采棉机样机上应用试验表明:该应用层协议不仅能满足实际需要,而且还具有极强的移植性、扩展性,在其他大型农业机械或工程机械的监控系统中具有通用性。