铅胁迫对澳洲坚果幼苗生长及生理特性的影响

为探究澳洲坚果（Macadamia integrifolia）对土壤铅胁迫的耐受性,以3年生澳洲坚果实生苗为材料,研究不同浓度铅处理下（0、200、400、800、1 200、1 600和2 000 mg/kg）澳洲坚果幼苗生长及生理特性的变化。结果表明,除地径增量和可溶性糖含量外,铅浓度对澳洲坚果幼苗生长及生理特性均影响极显著。随铅浓度升高,幼苗株高和地径增量、叶绿素含量、可溶性蛋白和游离脯氨酸含量及SOD和POD活性均呈先升后降的趋势;可溶性糖含量呈先降后升的趋势;MDA含量逐渐上升。澳洲坚果幼苗对1 200 mg/kg以下的铅胁迫有一定抗性;1 200 mg/kg以上会对其造成毒害,抑制其生长。     

The production of short chain fatty acid and colonic development in weaning piglets

Weaning process widely affects the small intestinal structure and function in piglets, while the responses of large intestine to weaning stress are still obscure. The purpose of this study was to determine the developmental changes (i.e., short chain fatty acids (SCFAs) concentrations, growth parameters, crypt‐related indices and antioxidant capacity) in colon of piglet during weaning. Forty piglets were weaned at day 21 and euthanized to collect colonic tissues and digesta samples on day 0, 1, 3, 7 and 14 post‐weaning (n = 8). Piglet growth performance was improved (p < .001) on day 7 and 14 post‐weaning. The concentrations of acetate, propionate, butyrate, valerate, isobutyrate, isovalerate and total SCFAs were higher (p < .001) during the late post‐weaning period. The mRNA abundances of SCFAs transporters were greater (p < .001) on day 7 and 14. The absolute and relative weights, absolute length and perimeter of colon were greater (p < .001) on day 7 and 14. Similarly, post‐weaning increases (p < .001) in colonic crypt depth and Ki67 positive cells numbers per crypt were observed during the same period. Colonic crypt fission indices decreased (p < .01), while total crypt numbers increased (p < .001) on day 14 after weaning. Moreover, total SCFAs concentration was significantly associated with colonic growth parameters and Ki67 cells/crypt (p < .001). In addition, catalase content was decreased on day 3, 7, and 14, whereas, the concentrations of total superoxide dismutase (T‐SOD) and manganese‐containing superoxide dismutase (MnSOD) were higher (p < .05) on day 1 and 3 post‐weaning. These results showed that weaning process has a significant effect on colonic growth and development, which might be associated with the change of SCFAs concentrations in colon.     

模拟降雨格局变化对虎尾草分株和根系特征的影响

作为全球气候变化的重要组成部分,降雨格局变化能够对各类植物产生不同的影响.虎尾草为退化盐碱草地恢复的主要先锋种植物之一,降雨格局变化如何影响其分株和根系等特征对于全球变化背景下退化盐碱地的生态恢复至关重要.本研究通过人工模拟降雨格局变化试验,设置了3个降水量(减少30％、不变、增加30％)和2个降雨间隔(1、2d),研...     

Prevalence and risk factors for contamination with Listeria monocytogenes of imported and exported meat and fish products in Switzerland, 1992-2000

A total of 2053 import and 164 export samples from 425 production plants were examined over a 9-year period (1992-2000) for the presence of Listeria monocytogenes (L. monocytogenes) in Switzerland. Overall, 282 samples (12.2%) and 85 plants (20.5%) harbored the pathogen. The highest isolation risk was for marinated fish (38%); the lowest was in cured- and dried-meat products.Unconditional fixed-effect logistic regression was used to identify the main hazards associated with the presence of L. monocytogenes. The plant-level model considered potential risk factors for a positive culture operating at the production-plant level by including a random effect of plant and year.Food category was the only significant factor; sampling site, country of origin and season were not significant. Marinated fish was a strong predictor for positive culture, whereas cooked- and cured-meat products were protective. Plant and year effects were significant. Control measures should be focused on specific food items in each production plant.     

An unusual case of concomitant infection with chicken astrovirus and group A avian rotavirus in broilers with a history of severe clinical signs

A molecular study of intestinal samples from 21 broiler flocks with a history of enteritis revealed that 23.8% and 14.3% were positive for chicken astrovirus (CAstV) and avian rotavirus (ARV), respectively. CAstV and group A ARV were simultaneously detected in only one broiler flock. Birds in this group developed the significant intestinal lesions characterized by frothy contents, paleness, and thin intestinal walls. In this report we present an unusual case of runting stunting syndrome (RSS) with a history of high mortality and growth retardation in broiler chickens. We also make the first identification of CAstV and group A ARV in broiler chickens in Korea.     

吡虫啉在不同施药时间对玉米叶绿素含量的影响

对大田栽培作物玉米,在不同时间,用喷雾器喷施不同浓度杀虫剂吡虫啉,24h后测定玉米叶绿素和类胡萝卜素的含量.结果表明,上午喷施药剂促使玉米叶绿素含量增加最多,其次是中午,下午施药玉米叶绿素含量增加最小.     

甘肃省农作物秸秆资源现状及利用潜力研究

[目的]厘清甘肃省农作物秸秆资源现状,可为减少农业面源污染,促进全省秸秆综合利用和农业可持续发展提供数据支撑。[方法]本文基于统计数据和农户调研数据,综述了全省主要农作物秸秆资源产生量、利用现状、秸秆资源量评估的主要影响因素及利用模式建议。分析了秸秆资源量变化趋势(2007-2017年);[结果]2017年甘肃省农作物秸秆理论资源量为1040.03万吨,可收集量923.62万吨,小麦、玉米、大豆三类农作物秸秆占总量的87.33%,利用量为829.79万吨,综合利用率达89.84%,资源化利用方式以饲料化为主,肥料化为辅。秸秆主要利用方式包括秸－饲－肥饲料化利用、 秸－菌－肥基料化利用、秸－沼－肥燃料化利用、秸－炭－肥原料化利用。[结论]以循环农业的角度出发,秸秆炭化还田作为一种重要的秸秆利用方式之一,具有培肥地力、固氮减排、间接增产增收等积极效用,可作为现有基础下秸秆资源化利用的一条重要的可行性新途径,对于资源短缺、环境污染和农业可持续发展具有重要意义。     

进境哈萨克斯坦向日葵种子中向日葵黑茎病菌的鉴定

自进境哈萨克斯坦向日葵种子中,采用常规平板分离法获得1株疑似向日葵黑茎病菌Plenodomus lindquistii菌株LL4,通过生物学性状、ITS序列测定和比对分析及致病性测定等方法对其进行了鉴定。结果表明,该病菌在PDA平板上培养初期菌丝无色,分隔分枝多,后期菌丝褐色或深褐色,常膨大;分生孢子器暗褐色,分散或聚集,球形、近球形或不规则形,大小为71.2~361.8μm;分生孢子形态变化较大,无色,单孢,肾形至椭圆形,大小为3.6~8.2μm×2.2~3.7μm,常含有2个油球;培养期间未见有性阶段。基于ITS序列分析比对发现,菌株LL4与Gen Bank中多个向日葵黑茎病菌分离物序列同源性达99%以上,系统进化树显示其与其它向日葵黑茎病菌分离物聚在同一个分支。菌株LL4可侵染向日葵根茎部,造成典型黑茎病症状。表明分离获得的菌株LL4为向日葵黑茎病菌P.lindquistii。     

兔组织中阿维菌素残留的高效液相色谱法测定研究

阿维菌素是一种新型大环内酯类广谱抗寄生虫药物。本试验采用乙腈提取,然后通过氧化铝柱净化组织样本,经Ｎ－甲基咪唑与三氟醋酸酐衍生化后,用高效液相色谱－荧光检测器在激发波长为３６５ｎｍ,发射波长为４７０ｎｍ处,对衍生化产物进行测定。