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1.
环境蠕变对农业病虫草鼠害的潜在影响 总被引：2，自引：2，他引：0
重点讨论了在全球气候变暖的大背景下,农业病虫草鼠害加重和新的病虫草鼠出现也作为一种蠕变现象正在遭受气候变化的影响和冲击。其主要表现在农业有害生物(病、虫、草、鼠)地理分布范围扩大、越冬界限北移、农田害虫害鼠发育时间缩短、繁殖代数增加、种群增长率加快、发生提早、危害加重、病毒病增加、新病虫草鼠出现等等。 相似文献
2.
Sulfate chitosan derivatives have good solubility and therapeutic effect on the cell model of NAFLD. The aim of this study was to examine the therapeutic effect of sulfate chitosan derivatives on NAFLD. The male Wistar rats were orally fed high fat emulsion and received sulfate chitosan derivatives for 5 weeks to determine the pre-treatment effect of sulfate chitosan derivatives on NAFLD. To evaluate the therapeutic effect of sulfate chitosan derivatives on NAFLD, the rats were orally fed with high concentration emulsion for 5 weeks, followed by sulfate chitosan derivatives for 3 weeks. Histological analysis and biomedical assays showed that sulfate chitosan derivatives can dramatically prevent the development of hepatic steatosis in hepatocyte cells. In animal studies, pre-treatment and treatment with sulfate chitosan derivatives significantly protected against hepatic steatohepatitis induced by high fat diet according to histological analysis. Furthermore, increased TC, ALT, MDA, and LEP in NAFLD were significantly ameliorated by pre-treatment and treatment with sulfate chitosan derivatives. Furthermore, increased TG, AST, and TNF-α in NAFLD were significantly ameliorated by treatment with sulfate chitosan derivatives. Sulfate chitosan derivatives have good pre-treatment and therapeutic effect on NAFLD. 相似文献
3.
目的:采用肾血管性高血压大鼠模型(两肾一夹型)观察海洋硫酸多糖DPS对肾血管性高血压大鼠的降压作用.方法:(1)急性降压实验:DPS分别以1.56, 3.13, 6.25, 12.50, 25.00 mg/kg剂量单次舌下静脉注射给药,给药前后以颈总动脉插管法测定大鼠动脉血压和心率.(2)口服预防给药实验:在肾血管性高血压大鼠造模第二天起DPS以12.50 , 25.00,50.00 mg/kg口服预防给药五周,每日给药一次.于给药前、给药后第三周和第六周分别以尾动脉测压法测定大鼠动脉血压和心率.血管紧张素转化酶卡托普利(14 mg/kg)作为口服预防给药实验阳性对照药.结果:在急性降压实验中,DPS能够显著降低肾血管性高血压大鼠的收缩压和舒张压且其降压强度呈剂量依赖性,在降压的同时伴有心率减慢.DPS口服预防给药五周,能够呈剂量依赖性防止肾血管性高血压大鼠的收缩压和舒张压升高,且DPS 50.00 mg/kg的降压效果与卡托普利14 mg/kg相当.结论:海洋硫酸多糖DPS对肾血管性高血压大鼠的有良好的降压作用. 相似文献
4.
There is growing recognition among ecologists that ecosystem engineers play important roles in creating habitat for other species, but the comparative and combined effects of co-existing engineers are not well known. Here, we evaluated the separate and interactive effects of two burrowing rodents, Gunnison's prairie dogs (Cynomys gunnisoni) and banner-tailed kangaroo rats (Dipodomys spectabilis), on lizards in the Chihuahuan Desert grassland (USA). We found that the mounds and burrow systems of both rodent species provided important habitat for lizards, with lizard abundance being 2 to 4-fold higher on mounds than in adjacent areas without mounds. Kangaroo rat mounds supported greater numbers of lizards than prairie dog mounds, but the prairie dog colony with kangaroo rats supported 2-times more lizards than the landscape with only kangaroo rats. A greater number of mound habitats were available for lizards where prairie dogs and kangaroo rats co-occurred, and the rodents created unique structural mound types with different spatial distributions on the landscape. Our results demonstrate the importance of burrowing rodents in creating habitat for other animals, and that the combined effect of ecosystem engineers, especially those with large ecological roles, can be complementary and additive in areas where they co-occur. 相似文献
5.
模拟热浪天气对冠心病影响及其机理实验研究 总被引：3，自引：3，他引：0
通过模拟热浪天气对冠心病小鼠影响实验研究,探讨高温热浪对冠心病影响的机理.应用TEM1880气象环境模拟箱模拟一次实际的热浪天气过程,按体重大小将18只冠心病小鼠分配至6个区组,每个区组3只,再将3只小鼠随机分配到对照组、热浪组、热浪BH4组中,每组共有6只小鼠.放入模拟箱内,使其受热浪天气影响,模拟热浪天气结束后,采用断头采血和摘取心脏,测量各组小鼠的ET-1、NO、HSP60、SOD、TNF、sICAM-1和HIF-1α的含量.结果表明,热浪天气可导致冠心病小鼠心肌组织SOD活性明显下降,而NO、HSP60、TNF、sICAM-1和HIF-1α的含量增加,但对ET-1水平没有任何影响.通过各项生化指标分析得知,热浪可诱导冠心病小鼠心肌组织HSP60含量明显增加,过多的HSP60可以活化免疫细胞,诱导内皮细胞、巨噬细胞分泌大量ICAM-1、TNF-α等炎性细胞因子,进而激活体内炎症系统,破坏冠状血管内皮细胞结构,使血管内膜通透性增高,心脏组织SOD活性下降,使氧化血液中的脂蛋白加剧,大量的胆固醇加速了胆固醇穿透内膜在血管内壁上的沉积,形成动脉粥样硬化,致使冠心病病情加重;从而诱导ICAM-1、血栓素等血管活性物增加,造成血粘度增加,促使血栓的形成;抑制脂蛋白酯酶活性,诱导脂质浸润血管内膜,形成动脉硬化斑块,同时控制巨噬细胞的胆固醇代谢,利于脂质物质沉积于血管壁而增加冠脉疾病风险.该实验是高温热浪导致冠心病病情加重,甚至死亡的初步机理研究成果,可为我国高温热浪预警服务和冠心病防御等提供理论依据. 相似文献
6.
研究了海带中砷元素在大鼠体内代谢过程中的形态变化。采用Wistar大鼠按体重随机分为空白对照组和高剂量海带组、低剂量海带组,每组10只,雌雄各半,分别灌胃基础饲料和添加50%、25%海带粉(占饲料粉的比例)的饲料。实验结束后,取大鼠血液、胃内容物、回肠内容物、回盲部内容物和大肠末端内容物,采用高效液相色谱-电感耦合等离子体质谱法(HPLC-ICP-MS)测定样品中的砷形态和含量。结果表明,海带中的砷在大鼠体内代谢过程中形态发生变化;空白对照组大鼠胃、回肠、回盲部和大肠末端的内容物中砷含量较低,主要砷形态为二甲基砷(DMA)和五价砷(AsⅤ),且不含有砷糖化合物;添加海带组大鼠胃、回肠、回盲部、大肠末端内容物中含有砷糖化合物及少量的砷胆碱(AsC)、砷甜菜碱(AsB)、DMA和AsⅤ,海带中的砷在大鼠的大肠末端主要以砷糖和小分子有机砷形态排出体外。空白对照组和添加海带组大鼠血液中的砷形态均为DMA和少量AsⅤ,添加海带组大鼠血液中未检出砷糖化合物。本研究旨在为阐明海带中砷元素在体内的代谢变化提供参考依据。 相似文献
7.
Low molecular weight peptide (LMWP) was prepared from clam Paphia undulate and its antiaging effect on D-galactose-induced acute aging in rats, aged Kunming mice, ultraviolet-exposed rats, and thermally injured rats was investigated. P. undulate flesh was homogenized and digested using papain under optimal conditions, then subjected to Sephadex G-25 chromatography to isolate the LMWP. Administration of LMWP significantly reversed D-galactose-induced oxidative stress by increasing the activities of glutathione peroxidase (GPx) and catalase (CAT), and by decreasing the level of malondialdehyde (MDA). This process was accompanied by increased collagen synthesis. The LMWP prevented photoaging and promoted dermis recovery and remission of elastic fiber hyperplasia. Furthermore, treatment with the LMWP helped to regenerate elastic fibers and the collagen network, increased superoxide dismutase (SOD) in the serum and significantly decreased MDA. Thermal scald-induced inflammation and edema were also relieved by the LWMP, while wound healing in skin was promoted. These results suggest that the LMWP from P. undulate could serve as a new antiaging substance in cosmetics. 相似文献
8.
对重要干扰过程导致森林植被向大气中的碳排放量进行评估,对于合理评估森林碳汇功能及其在应对全球气候变化中的作用是有重要意义的。本文基于有关森林干扰发生情况的林业统计资料和有关干扰引起生物量C转移过程与比例的假设条件,估算了近20年来采伐、火灾与病虫鼠害三种主要干扰每年从森林植被直接排放到大气中的C量。结果表明,近20年来,中国森林遭受了比较强烈的采伐、火灾与病虫鼠害干扰,并且这三种干扰在进入21世纪后有着比较明显的增加趋势。相应地,在1990-2009年间,采伐、火灾与病虫鼠害的C排放量年均分别为3425.16万tC、161.29万tC、428.80万tC,合计为4015.24万t。三种干扰的总C排放量在1990-1999年间年均为3079.40万t,在2000-2009年间年均为4951.09万t。从不同森林类型分布区的排放来看,中国森林主要干扰的年均C排放量及其年代际变化呈现比较明显的区域特征。干扰对中国森林碳平衡有着重大影响,针对干扰的森林管理可能具有较大的增汇潜力,并且在未来有关森林与陆地生态系统碳收支的模型研究中需考虑主要干扰的影响。 相似文献
9.
采用肾血管性高血压大鼠模型 (两肾一夹型 )观察海洋硫酸多糖 DPS对肾血管性高血压大鼠血清中一氧化氮 (NO)和血浆中血管紧张素 II(Ang II)及内皮素 - 1(ET- 1)含量的影响。 DPS在肾血管性高血压大鼠造模第二天起分别以 12 .50 ,2 5.0 0 ,50 .0 0 mg/ kg口服预防给药五周 ,每日给药一次。于给药前、给药后第三周和第六周分别测定动脉血压和心率。实验结束前 ,从每只大鼠取血 6 m L ,用试剂盒测定血清中 NO的含量 ;用放射免疫法测定血浆中 Ang II和 ET- 1的含量。血管紧张素转化酶抑制剂卡托普利 (14mg/ kg)作为本实验阳性对照药。结果 :DPS口服预防给药五周 ,可显著增加血清中 NO的含量和降低血浆中 ET- 1的含量 ,且呈剂量依赖性 ;DPS亦能降低血浆中 Ang II的含量 ,但未见剂量依赖性。结论 :海洋硫酸多糖 DPS对肾血管性高血压大鼠的降压作用机制可能与其促进体内 NO生成或释放、降低 AngII和 ET- 1的含量有关 相似文献
10.
类肝素新药“916”对高脂血症大鼠血清脂蛋白及过氧化脂质产物含量的影响(英文) 总被引：1，自引：0，他引：1
初步探讨了类肝素海洋新药“916”对高脂血症大鼠血清脂蛋白胆固醇及过氧化脂质的影响。结果表明,“916”能够明显抑制高脂饲料诱发的血清总但固醇及低密度脂蛋白胆固醇的升高;显著降低高脂血症大鼠血清过氧化脂质的含量。 相似文献