基于最小限制水分范围评价不同耕作方式对土壤有机碳的影响

以2009年吉林省德惠市中层黑土上进行了8a的田间定位试验小区土壤为研究对象,对免耕和秋翻两种耕作方式及玉米-大豆轮作和玉米连作两种种植方式下耕层有机碳进行分析,分别采用加权平均和分层两种方法计算最小限制水分范围(LLWR),用其评价不同耕作方式对土壤有机碳的影响.结果表明,免耕在玉米-大豆轮作和玉米连作下0-5 cm土壤有机碳含量分别比秋翻增加了15.2％和11.5％ (P＜0.05).采用加权平均法计算的LLWR值为0.148-0.166 cm3/cm3,不同耕作方式下玉米-大豆轮作的LLWR高于玉米连作且在两种种植方式下均表现出免耕小于秋翻的特点;利用分层法计算得到的LLWR值介于0.130-0.173 cm3/cm3之间,玉米-大豆轮作和玉米连作下免耕0-5 cm LLWR均显著小于秋翻,而5-30 cm LLWR数值免耕大于秋翻(P＞0.05);玉米-大豆轮作下0-30 cm各层LLWR均高于玉米连作.由于LLWR可以评价不同耕作方式对土壤有机碳的影响,因此采用加权平均法计算的LLWR可以客观的反映不同耕作处理尤其是种植方式对土壤有机碳的影响;而采用分层法计算的LLWR则更清晰的刻画了土壤表层与亚表层固碳能力的差异.     

Multi-faced neuroprotective effects of Ginsenoside Rg1 in an Alzheimer mouse model

There has been no extensive characterization of the effects of Ginsenoside Rg1, a pharmacological active component purified from the nature product ginseng, in an Alzheimer's disease mouse model. The well-characterized transgenic Alzheimer disease (AD) mice over expressing amyloid precursor protein (APP)/Aβ (Tg mAPP) and nontransgenic (nonTg) littermates at age of 6 and 9 months were treated with Rg 1 for three months via intraperitoneal injection. Mice were then evaluated for changes in amyloid pathology, neuropathology and behavior. Tg mAPP treated with Rg1 showed a significant reduction of cerebral Aβ levels, reversal of certain neuropathological changes, and preservation of spatial learning and memory, as compared to vehicle-treated mice. Rg1 treatment inhibited activity of γ-secretase in both Tg mAPP mice and B103-APP cells, indicating the involvement of Rg1 in APP regulation pathway. Furthermore, administration of Rg1 enhanced PKA/CREB pathway activation in mAPP mice and in cultured cortical neurons exposed to Aβ or glutamate-mediated synaptic stress. Most importantly, the beneficial effects on attenuation of cerebral Aβ accumulation, improvement in neuropathological and behavioral changes can be extended to the aged mAPP mice, even to 12-13 months old mice that had extensive amyloid pathology and severe neuropathological and cognitive malfunction. These studies indicate that Rg1 has profound multi-faced and neuroprotective effects in an AD mouse model. Rg1 induces neuroprotection through ameliorating amyloid pathology, modulating APP process, improving cognition, and activating PKA/CREB signaling. These findings provide a new perspective for the treatment of AD and demonstrate potential for a new class of drugs for AD treatment.     

翘嘴鳜肌球蛋白轻链3b基因(MLC3b)的分子克隆和特征分析

翘嘴鳜以其优良肉质性状近期已成为中国极具商品价值和大力推广的人工养殖名贵鱼类之一。为了解其控制优良肉质性状的遗传基础,本文采用同源克隆RT-PCR方法,获得该鱼肌球蛋白轻链MLC3b基因cDNA序列,该基因cDNA序列为453bp,编码150个氨基酸残基,通过PROSITE tools软件预测显示,该轻链具有两个保守的EF-手相结构和一个C-末端保守序列,且该MLC3轻链N端没有高等脊椎动物特有标志序列。MLC3b基因cDNA序列与MLC3a编码区的同源性达97.7%。本研究结果将为名贵鱼类肉质结构基因及功能的研究提供分子生物学基础。     

海洋真菌Aspergillus sp.SCSGAF 0076与细菌Bacillus sp.MNMCCE001共培养次生代谢产物

【目的】阐明海洋真菌Aspergillus sp.SCSGAF 0076与细菌Bacillus sp.MNMCCE 001在平板上共培养时产生的主要抗菌物质和红色素的化学结构。【方法】在固体淀粉培养基上分别进行Aspergillus sp.SCSGAF 0076纯培养、以及SCSGAF 0076和Bacillus sp.MNMCCE 001共培养,培养3 d后分别对纯培养和共培养的培养基进行萃取浓缩得到浸膏,运用高效液相色谱分析比较纯培养和共培养所得浸膏的化学分成的差异,并采用抗菌活性追踪法,结合硅胶柱层析、凝胶柱层析和高效液相色谱等分离方法从共培养浸膏中分离纯化抗菌物质和红色素,运用波谱解析法鉴定化合物的结构。【结果】通过高效液相色谱分析发现,共培养与纯培养的主要次生代谢产物没明显差异,但抗菌物质和红色素的含量差别明显。从这两株菌共培养的发酵产物中分离鉴定了4个化合物,包括抗菌物质青霉酸(1)、青霉酸类似物5(6)-dihydropenicillic acid(2)和9-chloro-8-hydroxy-8,9-deoxyasperlactone(3)、以及红色素viopurpurin(4)。【结论】初步阐明了Aspergillus sp.SCSGAF 0076与Bacillus sp.MNMCCE 001共培养时由Aspergillus sp.SCSGAF 0076产生的主要抗菌活性化合物是青霉酸,伴随明显增多的主要红色素是viopurpurin,二者产率均比Aspergillus sp.SCSGAF 0076纯培养时高。     

四数獐牙菜的胚胎学及其系统学意义

四数獐牙菜花药四室,药壁发育为双子叶型;绒毡层腺质型。小孢子母细胞减数分裂为同时型, 四分体的排列方式为四面体形;成熟花粉为3-细胞。子房2心皮,2心皮连接处强烈内凸,4列胚珠。薄 珠心,单珠被,直生胚珠。胚囊发育为蓼型。胚乳发育为核型。胚胎发育为茄型酸浆I变型。反足细胞 在胚囊成熟时期宿存。果实成熟时,种子只发育至球型胚阶段。承珠盘存在。与已研究的獐牙菜种类 的胚胎特征相比较,该种存在三个显著的特点：直生胚珠,心皮连接处强烈内凸,承珠盘存在。这三个特 征目前仅在龙胆族中的花锚属中发现。经过性状分析,它们均是演征,此三个共有演征表明四数獐牙菜 与花锚属是一单系群,它们的亲缘关系最近。这与Yun &; Kupfer(1995)的分子证据部分吻合,因为分 子系统树上的花锚单系支包括花锚、四数獐牙菜和北美的密花属(广义獐牙菜属中的密花组),而后者的 胚胎学特征未有任何报道。胚胎学研究暗示四数獐牙菜的分类学等级有待重新评价,广义的獐牙菜属 有可能不是一单系发生群。     

黄土区土壤放射性的生物循环

研究了不同类型土壤中放射性物质的生物学循环和平衡问题。结果表明,土壤中放射性核素剖面分布的总趋势是沿发生层往下逐步减少。其生物积聚系数因不同核素而变动在1.06—1.44间。放射性物质在各类植物体内的含量顺序是:牧草>农业作物≥灌木≥果树>乔木。植物对α放射性的富集系数一般均小于0.10,而β放射性的富集系数大都处于0.5—1.0间.不同土地利用情况下土壤放射性可分为积累、消耗和中间3种平衡类型。     

马尾松GOT、LDH和MDH同工酶的遗传方式和连锁关系

本文采用聚丙烯酰胺凝胶电泳研究了马尾松三种同工酶的遗传方式和连锁关系。结果表明,GOT、LDH和MDH三种同工酶的遗传表达稳定,分别受4个、2个和4个位点控制。只有一对位点(MDH-3和MDH-4)间存在着紧密的连锁关系。     

Graphene/Au-Enhanced Plastic Clad Silica Fiber Optic Surface Plasmon Resonance Sensor

Owing to its large surface-to-volume ratio and good biocompatibility, graphene has been identified as a highly promising candidate as the sensing layer for fiber optic sensors. In this paper, a graphene/Au-enhanced plastic clad silica (PCS) fiber optic surface plasmon resonance (SPR) sensor is presented. A sheet of graphene is employed as a sensing layer coated around the Au film on the PCS fiber surface. The PCS fiber is chosen to overcome the shortcomings of the structured microfibers and construct a more stable and reliable device. It is demonstrated that the introduction of graphene can enhance the intensity of the confined electric field surrounding the sensing layer, which results in a stronger light-matter interaction and thereby the improved sensitivity. The sensitivity of graphene-based fiber optic SPR sensor exhibits more than two times larger than that of the conventional gold film SPR fiber optic sensor. Furthermore, the dynamic response analyses reveal that the graphene/Au fiber optic SPR sensor exhibits a fast response (5 s response time) and excellent reusability (3.5% fluctuation) to the protein biomolecules. Such a graphene/Au fiber optic SPR sensor with high sensitivity and fast response shows a great promise for the future biochemical application.