A molecular mechanism of resistance to streptomycin in <Emphasis Type="Italic">Xanthomonas oryzae</Emphasis> pv. <Emphasis Type="Italic">oryzicola</Emphasis>

Xanthomonas oryzae pv. oryzicola, the causal agent of rice leaf streak disease, was found to be sensitive to streptomycin (an aminocyclitol glycoside antibiotic), by inhibition of protein synthesis resulting from interference with translational proofreading. This study aimed to determine the molecular resistance mechanism of X. oryzae pv. oryzicola to streptomycin. Seven streptomycin-resistant mutants were obtained by UV induction or streptomycin selection. These mutants can grow at 100 μg ml⁻¹ of streptomycin while the wild-type strain (RS105) cannot grow at 5 μg ml⁻¹. Sequencing indicated that the rpsL gene encoding ribosomal protein S12 has 375 bp encoding 125 amino acid residues. In all resistant strains, a mutation in which AAG was substituted for AGG (Lys→Arg) occurred either at codon 43 or 88. Two plasmids, pUFRRS and pUFRRX, were constructed by ligating the rpsL gene into the cosmid pUFR034. The plasmids pUFRRS and pUFRRX containing the Lys→Arg mutation of the rpsL gene conferred streptomycin resistance to the sensitive wild-type strain by electroporation. Both transformants, RS1 and RS2, could grow in the medium containing 50 μg ml⁻¹ of streptomycin. A mutation at codon 43 or 88 in rpsL can result in resistance of Xanthomonas oryzae pv. oryzicola to streptomycin.     

氯虫苯甲酰胺和氟虫双酰胺对不同虫态甜菜夜蛾的毒力作用

采用浸叶法、点滴法、夹毒叶片法、成虫药膜法、饲喂毒营养液法测定了氯虫苯甲酰胺、氟虫双酰胺对甜菜夜蛾卵、2~4龄幼虫、成虫的活性和对4龄幼虫的拒食活性,以明确氯虫苯甲酰胺和氟虫双酰胺对不同虫态甜菜夜蛾的毒力作用。结果表明,两种杀虫剂均不具有杀卵活性,但可以明显降低初孵幼虫存活率;氯虫苯甲酰胺、氟虫双酰胺均对2龄幼虫活性最高,分别为3龄幼虫的1.50、6.17倍和4龄幼虫的22.25、44.95倍,对4龄幼虫胃毒活性分别为触杀活性的14.10、8.44倍;氯虫苯甲酰胺对甜菜夜蛾成虫毒力为氟虫双酰胺的25.53~34.19倍。氯虫苯甲酰胺、氟虫双酰胺对甜菜夜蛾幼虫表现出较强的拒食作用, 至处理后48 h拒食率达到最高, 分别为 82.73%、84.15%,显著高于对照药剂甲维盐各浓度处理,处理试虫虫体皱缩、体节缩短,体重增加率明显低于对照和甲维盐各处理。     

Diet composition, herbage intake and digestibility in Inner Mongolian Cashmere goats grazing on native Leymus chinensis plant communities

The botanical composition, intake and digestibility of the diet selected by Inner Mongolian Cashmere goats grazing on a native Leymus chinensis plant community were measured in two grazing periods (June and August) using the n-alkane markers. In each grazing period, 48 Inner Mongolian Cashmere goats (24 wethers and 24 does with an average live weight of 22.1 ± 1.2 kg and 19.6 ± 0.8 kg, respectively) were divided in two groups (G1: grazing group; G2: cage-fed group) of 24 animals each. Based on the observation of G1 grazing behaviour, G2 goats were fed on herbage obtained by a simulative method and were housed in metabolism cages to determine the alkane faecal recoveries. Diet composition was estimated by comparing the odd-chain n-alkane pattern (C₂₅–C₃₅) of the selected plant species with the n-alkane faecal concentrations, corrected for their incomplete faecal recovery. The alkane pair C₃₂:C₃₃ and C₃₆ alkane were used to estimate intake and diet digestibility, respectively. The results showed that the increase of herbage availability from June to August, resulted in higher (P < 0.05) DM, CP, ME, ADF and NDF intake of both wethers and does, with no evident changes in ADF and NDF intake in does., The intake of nutrients differed significantly between wethers and does in both experimental periods, except for NDF in EP1 and ME in EP2. Differences between grazing seasons and goats' sex in nutrients digestibility were not observed. Diet composition indicated seasonal differences, being Sonchus brachyotus, Artemisia frigida and Phragmites communis the main components of the diet in June. However, Suaeda corniculata, Chloris virgata, Xanthium sibiricum and Echinochloa crusgalli became the main diet components in August. Moreover, the sex affected significantly the diet choices in both grazing periods.     

中国-巴基斯坦喀喇昆仑公路沿线野生动物区系研究

中国-巴基斯坦喀喇昆仑公路（以下简称＂中巴公路＂）是中国政府于20世纪60年代中期援建的一条连接中国西部城市喀什和巴基斯坦北部城市塔科特的国际公路。2009年4月、7月、9月和2010年6～7月对中巴公路沿线分布的动物进行了考察,经全面系统分类、整理和统计,该地区共有陆栖野生动物22目51科105属147种,其中爬行类1目3科5属8种,鸟类14目34科72属103种,哺乳类/兽类7目14科28属36种。从野生动物分布的种类数量上看,分布最少的是爬行类（8种）,而较多的是鸟类（103种）和哺乳类/兽类（36种）,分别占该地区分布野生脊椎动物种数的5.44%、70.07%和24.49%。野生动物区系以北方广布种、高地型、古北型和中亚型为主,全北型、东洋型和喜马拉雅-横断山型渗透混杂,表明古北界温带陆栖动物地理属性是该地区动物区系的基本特征之所在。     

农三师猪弓形虫病血清学调查与分析

弓形虫病是龚第弓形虫引起的一种人和多种动物共患寄生虫病。本实验通过酶联免疫吸附(ELISA)试验对采自农三师辖区8个团场的不同养殖规模猪场的900份猪血清进行弓形虫病的抗体检测,结果表明猪弓形虫病在我师呈散发性流行。样品阳性率平均为36.33%,各辖区之间的抗体阳性率有一定差异,最高为49.16%,最低为21.33%。初步掌握我师猪弓形虫病的感染状况,为基层的防治工作提供技术指导。     

复方泰妙菌素粉对鸡败血霉形体病的药效研究

将200只试验鸡分为5组,通过饮水给药泰妙菌素粉。观蔡其实验性鸡败血霉形体病的治疗效果。结果表明：复方泰妙菌素粉200mg／L饮水给药组死亡率。治愈率显著低于对照组0P〈O.05.     

青岛市某猪场猪瘟的发生、诊断与防治报告

青岛某大型养猪场地处城阳区，饲养有杜洛克、长白等优良品种。饲养种母猪600多头，种公猪13头，全部采用人工授精配种。母猪平均每胎产仔数为9．75头。现存栏种公猪、母猪、仔猪、育成和育肥猪共有6500多头。全部采取自繁自养的方式。种母猪免疫过猪瘟、蓝耳病(PRRS)和伪狂犬病的二联灭活疫苗及细小病毒灭活疫苗。该场母猪免疫程序是：配种前一个月免疫4倍量猪瘟冻干苗，母猪产后在仔猪断奶前后进行猪瘟窝防(仔猪和母猪同时免疫)。     

甜菊糖甙对哺乳仔猪生产性能和健康状况的影响

为研究天然甜菊糖甙作为新型甜味剂在哺乳仔猪中的应用效果,随机选取16窝哺乳仔猪(杜长大,10头/窝)分为4组,每组4个重复,分别饲喂添加0、100、200和500g/t天然甜菊糖甙的教槽料,试验从仔猪7d时开始,至断奶后1周(28d)结束,期间每隔7d对仔猪采食量、增重和健康状况进行测定。结果发现,在哺乳仔猪日粮中添加100、200和500g/t的甜菊糖甙,显著提高仔猪断奶重(21d)和28d体重(P0.05),显著提高14～21和22～28d阶段内的平均日增重、平均日采食量和偏嗜指数(P0.05),而各甜味剂添加组间无显著性差异(P0.05)。7～28d内仔猪日增重200g/t组显著高于对照组和100g/t组。仔猪断奶(21d)后1周内腹泻率和腹泻指数有改善趋势(P0.05),7～28d内仔猪发病率200和500g/t天然甜菊糖甙组显著降低(P0.05)。因此,考虑成体投入的同时,在哺乳仔猪日粮中添加200g/t的天然甜菊糖甙,可取得良好的应用效果。     

Evapotranspiration and crop coefficient of Populus euphratica Oliv forest during the growing season in the extreme arid region northwest China

Based on successive observation, fifteen-day evapotranspiration (ET_c) of Populus euphratica Oliv forest, in the extreme arid region northwest China, was estimated by application of Bowen ratio-energy balance method (BREB) during the growing season in 2005. During the growing season in 2005, total ET_c was 446.96 mm. From the beginning of growing season, the ET_c increased gradually, and reached its maximum value of 6.724 mm d⁻¹ in the last fifteen days of June. Hereafter the ET_c dropped rapidly, and reached its minimum value of 1.215 mm d⁻¹ at the end of growing season. The variation pattern of crop coefficient (K_c) was similar to that of ET_c. From the beginning of growing season, the K_c value increased rapidly, and reached its maximum value of 0.623 in the last fifteen days of June. Afterward, with slowing growth of P. euphratica, the value dropped rapidly to the end of growing season. According to this study, the ET_c of P. euphratica forest is affected not only by meteorological factors, but by water content in soil.     

N-取代苯并口恶嗪酮类化合物的合成及其生物活性

为寻求具有高生物活性的新农药化合物,以邻氨基苯酚为原料设计合成了N-取代的苯并口恶嗪酮类化合物18个,其化学结构经1H NMR及元素分析确证。初步的生物活性测试结果表明,部分化合物具有良好的除草活性,如化合物c3、c5、c6、c7和c8在浓度为100mg/L时对苋菜Ambrosia tricolorL inn.的抑制率达90%。