Expression of inducible nitric oxide synthase in macrophages inversely correlates with parasitism of lymphoid tissues in dogs with visceral leishmaniasis

Background

There are only a few studies reporting the role of nitric oxide metabolites for controlling macrophage intracellular parasitism, and these are controversial. Therefore, the present study aimed to evaluate the expression of inducible nitric oxide synthase (iNOS) in the lymph nodes and spleen of dogs affected by visceral leishmaniasis through immunohistochemistry and to determine its correlation with tissue parasite burden and serum interferon (IFN)-γ levels. Twenty-eight dogs were selected and assigned to one of two groups, symptomatic (n = 18) and asymptomatic (n = 10), according to clinical status and laboratory evaluation. A negative control group (n = 6) from a non-endemic region for visceral leishmaniasis was included as well.

Results

Parasite density (amastigotes/mm²) was similar between clinical groups in the lymph nodes (P = 0.2401) and spleen (P = 0.8869). The density of iNOS⁺ cells was higher in infected dogs compared to controls (P < 0.05), without a significant difference in lymph node (P = 0.3257) and spleen (P = 0.5940) densities between symptomatic and asymptomatic dogs. A positive correlation was found between the number of iNOS⁺ cells in lymph nodes and interferon-γ levels (r = 0.3776; P = 0.0303), and there was a negative correlation between parasites and iNOS⁺ cell densities both in lymph nodes (r = −0.5341; P = 0.0034) and spleen (r = −0.4669; P = 0.0329).

Conclusion

The negative correlation observed between tissue parasitism and the expression of iNOS may be a reflection of NO acting on the control of parasites.     

饲料脂肪水平对拟穴青蟹仔蟹生长性能、体组成及消化酶活性的影响

本试验以初始体重为(0.042±0.002)g的拟穴青蟹仔蟹为研究对象,以鱼油和大豆油(1∶1)为脂肪源,配制脂肪水平分别为1.93%、3.95%、6.35%、8.14%、10.54%、12.30%、14.22%(实测值)的7种等氮等能试验饲料,养殖期为3周,用以研究饲料脂肪水平对拟穴青蟹仔蟹生长性能、体组成及消化酶活性的影响。每100只拟穴青蟹仔蟹为1个重复,每3个重复饲喂1种试验饲料。结果表明:1)饲料脂肪水平对拟穴青蟹仔蟹的增重率和特定生长率有显著影响(P0.05)。随着饲料脂肪水平的升高,增重率和特定生长率均呈先增后降的趋势,在饲料脂肪水平为8.14%时,增重率和特定生长率达到最大值。二次曲线回归分析确定当增重率达到最大值时,饲料脂肪水平为7.52%。拟穴青蟹仔蟹的成活率在饲料脂肪水平为14.22%的组最低,显著低于其余各组(P0.05)。2)饲料脂肪水平对全蟹中粗蛋白质和粗脂肪含量有影响显著(P0.05)。全蟹粗蛋白质含量随着饲料脂肪水平的升高先升后降,在饲料脂肪水平为8.14%的组全蟹粗蛋白质含量达到最高;全蟹粗脂肪含量则随着饲料脂肪水平的升高而持续上升,在饲料脂肪水平为14.22%的组全蟹粗脂肪含量达到最高。饲料脂肪水平对全蟹中水分和粗灰分含量没有显著影响(P0.05)。3)随着饲料脂肪水平的升高,拟穴青蟹仔蟹蛋白酶、淀粉酶和脂肪酶活性均呈先增后降的趋势,3种酶活性的最大值均出现在饲料脂肪水平为8.14%的组。由此得出,以增重率为评价指标,拟穴青蟹仔蟹饲料中最适脂肪水平为7.52%。     

桃新品种‘谷红2号’

‘谷红2号’桃由‘燕红’优良芽变育成。果实近圆形,平均单果质量275.4 g,最大单果质量650 g。果皮底色绿白,果面鲜红色;果肉白色,硬溶质,肉质紧密,浓甜,有香味;粘核,可溶性固形物14.2%。果实发育期152 d;在北京地区9月中下旬果实成熟。     

江西水土流失对防洪的影响及防治对策

江西省水土流失面积 3 5 2万km2 ,严重破坏了生态环境。水土流失导致河床和水库淤积 ,加剧了洪涝灾害程度。鄱阳湖承担着长江巨大超额洪水的调蓄 ,但湖区面积已由 2 0世纪 5 0年代初期的 5 10 0多km2 萎缩到现在的 3 95 0多km2 ,容积缩小了 72亿m3。本省境内的“五河”流入鄱阳湖内的水量达 14 0 0多亿m3,是该湖容积的 4倍多 ,可见搞好水土保持对长江防洪的重要意义。水土保持措施已在防洪减灾中发挥了重大作用 ,应把水土保持生态环境建设作为长江和本省新世纪水利发展战略的重要内容     

Insecticide resistance inFrankliniella occidentalis: Corroboration of laboratory assays with field data and cross-resistance in a cypermethrin-resistant strain

Field efficacy of five insecticides to a greenhouse strain ofFrankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) of known resistance status was studied. In a greenhouse trial, the mortality of aF. occidentalis strain (Uncali) which exhibited resistance only against cypermethrin in laboratory assays, reached 56%, 68%, 82%, 94% and 99%, 24 h after application of abamectin, cypermethrin, endosulfan, malathion and methomyl, respectively. In the laboratory, for larval mortality equal to that achieved in the field, much lower doses — half of the field dose of cypermethrin and endosulfan, and one-third and one-sixth of malathion and methomyl, respectively, were required in topical application. Because of differences between laboratory and field responses ofF. occidentalis to insecticides, a sound resistance evaluation program to determine field efficacy of insecticides is needed. Resistance increased 28.0- and 139.3-fold at LC₅₀ in theF. occidentalis strain subjected to 27 and 44 cycles of cypermethrin selection, respectively. A slight cross-resistance of two- to threefold was found with endosulfan, malathion and methomyl and no cross-resistance was observed with abamectin. http://www.phytoparasitica.org posting August 4, 2008.     

猪流行性腹泻病毒N蛋白核仁定位信号对宿主细胞周期的影响

为研究猪流行性腹泻病毒(PEDV)核衣壳蛋白(N)与宿主细胞相互作用,本研究根据前期已经鉴定的PEDV N蛋白核仁定位信号序列,利用重叠延伸PCR(SOE-PCR)方法扩增出核仁定位信号序列缺失的PEDV N基因(dN),并将其与真核表达载体pAc-GFP-C1连接,构建重组质粒pAc-GFP-dN。将pAc-GFP-dN转染于Vero E6细胞中,利用激光共聚焦显微镜分析重组质粒pAc-GFP-dN表达蛋白的定位情况,并利用流式细胞仪检测转染细胞的周期变化。实验结果表明:与完整的N蛋白相比,缺失核仁定位信号的N蛋白不能定位于细胞核仁,同时丧失了使宿主细胞周期在G2/M期停滞的能力,从而揭示了N蛋白核仁定位信号对宿主细胞具有重要的影响。     

旱田中耕节水灌溉设备的研究

分析了节水灌溉现状；以玉米苗期为研究对象，结合黑龙江省旱作农业实际，提出了一种与中耕相结合的灌溉方式，为采用机械化灌溉方法解决作物苗期干旱问题提供参考。     

饲用复合酶对蛋用种鸡日粮磷的利用和生产性能的影响

本试验旨在研究低磷日粮添加复合酶制剂对蛋用种鸡磷的利用和生产性能的影响。选用972只24周龄罗曼褐父母代种鸡,分为3个处理,每处理6个重复,每重复54只种鸡。采用玉米-豆粕-杂粕型基础饲粮,正对照组含总磷0.55%,非植酸磷0.40%,不加酶;负对照组含总磷0.40%,非植酸磷0.21%,不加酶;试验组含总磷0.40%,非植酸磷0.21%,加酶制剂。试验期18周。结果表明:在低非植酸磷的日粮中添加复合酶,粪便中磷含量极显著低于正对照组(P<0.01);粪便中粗蛋白质含量显著低于正对照组和负对照组(P<0.05);显著改善蛋黃顔色(P<0.05);不影响生产性能、骨骼发育和蛋壳质量。添加200 g/t复合酶替代罗曼褐蛋用种鸡日粮中75%的磷酸氢钙能够降低饲料成本,提高养殖企业的经济效益,对罗曼褐蛋用种鸡生产性能无不利影响。     

Mechanism of elemene enhancing radiosensitivity of human glioma U251 cells

AIM To investigate the effect of elemene on the radiosensitivity of human glioma U251 cells and its mechanism. METHODS The U251 cells were used as a glioma model in vitro, and were exposed to different concentrations of elemene and different doses of radiation. The cell viability was measured by MTT assay, the apoptosis and cell cycle distribution were analyzed by flow cytometry, and the related protein levels were determined by Western blot. RESULTS Elemene inhibited the viability of U251 cells in vitro and enhanced the radiosensitivity of the cells. The cells in radiotherapy combined with elemene group had higher rates of early apoptosis, secondary necrosis and total cell death than those in radiation group. Elemene induced G₂/M phase arrest in the U251 cells. Elemene reduced the protein expression of cell division cycle protein 2 （Cdc2）, which resulted in the decrease in cyclin B1 expression induced by radiotherapy, thereby inhibiting the formation of cyclin B-Cdc2 complex. Elemene reduced Cdc2 activity by inhibiting the phosphorylation of Cdc2 protein at threonine 161, thereby inducing G₂/M phase arrest in the cells. It also mediated apoptosis by down-regulating survivin expression. CONCLUSION Elemene may increase the sensitivity of U251 cells to radiotherapy by down-regulating Cdc2 protein, decreasing cyclin B1 expression, inhibiting the formation of cylcin B-Cdc2 complex and down-regulating the expression of survivin.     

杂种落叶松的识别技术

杂种落叶松在抗早期落叶病、抗寒性等方面具有一定优势,冻害指数较日本落叶松低70%,早期落叶病发病率较兴安落叶松低15%、感病指数下降15%。根据针叶形态和一些生理生化手段可将杂种落叶松和亲本区分开来。