First isolation and identification of Elizabethkingia meningoseptica from cultured tiger frog, Rana tigerina rugulosa

Elizabethkingia meningoseptica has been recognised as an occasional but serious opportunistic bacterial pathogen to human beings. Recently, it was frequently isolated from tiger frog, Rana tigerina rugulosa, with cataract disease, which is the most common disease of unknown aetiology of frogs in Hainan, China. The purpose of this study was to identify and characterise the bacterial strains isolated from the recent outbreaks of cataract disease in farmed tiger frog in Hainan, China, and to evaluate their pathogenicity to the frog and their sensitivity to 20 chemotherapeutic agents.The 16S rRNA gene sequences of strains W0701 (1478 bp), W0702 (1477 bp) and W0703 (1478 bp) showed 98.6–98.7% similarity with the sequence of E. meningoseptica type strain (ATCC 13253) and 99.9–100% similarity with that of E. meningoseptica NTU 870424-IL. Six strains (W0701–W0706) were selected to represent 24 isolates retrieved from six moribund frogs. The morphological, physiological and biochemical characteristics of the six representative isolates were consistent with those of E. meningoseptica strains. The organisms were only susceptible to vancomycin and moderately susceptible to cefoperazone among the 20 investigated chemotherapeutic agents. Virulence test with strain W0702 was conducted and pathogenicity (by intramuscular injection) was demonstrated in the tiger frog. In conclusion, 24 isolates obtained from frogs with cataract disease were the E. meningoseptica strains highly pathogenic to tiger frog, and this is the first report of E. meningoseptica as a pathogen for tiger frog.     

水肥一体化对山地鲜桑椹商品性状的影响

为探索不同为微地形条件下水肥一体化工程技术对干热河谷区桑园果桑商品性状的影响,以盐边县刚成熟、正成熟和过成熟的鲜桑椹为研究对象,对比坡面雨养区(DN)、沟道两旁雨养区(WN)、坡面（水肥一体化）灌溉施肥区(DF)和沟道两旁（水肥一体化）灌溉施肥区(WF)桑椹的果长、果径、体积、质量、密度、果形指数和糖度的差异。结果表明：（1）灌溉施肥可以影响桑椹结果的物候特征,加速桑椹成熟。（2）灌溉施肥、微地形、灌溉施肥和微地形的交互作用对鲜桑椹的果长、果径、体积和果形指数具有极显著影响。（3）成熟度可以显著影响鲜桑椹的果长、果径和体积,但对鲜桑椹果形指数的影响不显著。 （4）在灌溉施肥条件(DF、WF)下,桑椹的成熟度越高,其密度和质量越高;在DN区,过成熟桑椹的密度和质量显著高于刚成熟和正成熟的桑椹;而在WN区,正成熟桑椹的密度质量显著高于过成熟和刚成熟的桑椹密度。（5）平均糖度最高的为WF区的过成熟桑椹,平均糖度高达18.01%,而最低的为WN区的刚成熟桑椹,平均糖度仅为11.76%。（6）DN区和WN区桑椹的商品性状的差异主要是外形和糖度的差异,WN区的桑椹比DN区糖度低、外形大。（7）WF区桑椹与DF区桑椹的商品性状差异不大。上述结果揭示了水分和养分供给调控桑椹商品性状的内在机制,即水分供应可促进鲜桑椹变大变重,施肥可让鲜桑椹口味更甜。     

饲用调味剂稳定性的评价与研究

本文阐述了通过冷冻聚焦顶空累积进样毛细管气相色谱评价调味剂稳定性的方法,并针对调味剂应用中大家所关切的问题,对市售仔猪调味剂加入饲料后自然贮放和制粒温度下加热不同时间“香气”的衰减情况进行了实际研究与探讨,分析了影响调味剂稳定性的主要因素及产品开发应用中应注意的问题。文章还结合动物偏好试验,得出了一些具有参考意义的结果。     

黄土高原不同粮草种植模式土壤碳氮及土壤酶活性

通过在陇中黄土高原半干旱区对苜蓿(Medicago sativa)-作物轮作地进行长期定位试验,探讨不同种植模式对土壤碳氮形态及其相关酶活性的影响。6种种植模式分别为苜蓿-苜蓿、苜蓿-休闲、苜蓿-小麦(Triticum aestivum)、苜蓿-玉米(Zea mays)、苜蓿-马铃薯(Solanum tuberosum)和苜蓿-谷子(Setaria italica)。结果表明,苜蓿-作物种植模式不利于土壤总有机碳的积累,而苜蓿翻耕后保持休闲则可维持较高的有机碳含量;与苜蓿连作相比,苜蓿-作物种植模式的土壤有机碳降低了1.60%~23.11%,全氮含量增加了3.81%~21.83%。不同作物对土壤养分吸收利用状况不同,进而引起土壤酶发生变化。与苜蓿连作相比,苜蓿粮食作物种植模式在降低土壤过氧化氢酶和蛋白酶活性的同时,提高了土壤硝酸还原酶活性;其中土壤过氧化氢酶活性和蛋白酶活性分别降低了5.20%~12.30%和15.03%~43.43%,硝酸还原酶活性提高了1.26%~28.79%。苜蓿连作和苜蓿-粮食作物种植模式间的土壤脲酶活性无显著差异(P0.05),但均高于苜蓿-休闲处理。相关性分析结果表明,土壤脲酶活性与土壤有机碳、全氮含量呈显著正相关(P0.05),可作为衡量土壤肥力的指标。     

环境DNA应用研究进展

近年来,环境DNA（eDNA）应用发展迅速,已涉及食品微生物、生物监测、群落生态学、古环境研究、保护生物学和入侵生态学等多个领域。基于eDNA的研究手段具有非侵入性、易于取样和能够探测隐秘物种等优点,因此eDNA是生态系统广泛直接取样的一种有吸引力的替代品。本文综述了eDNA的定义和发展历史,介绍了DNA条形码选择和设计、样品收集、DNA抽提、DNA扩增测序、DNA条形码数据分析等eDNA研究步骤,描述了eDNA在外来物种入侵、物种检测、生物量估算、水中生态系统监测等领域的应用,总结出eDNA研究中存在的问题,并展望该方法的应用前景。本文为全面了解eDNA的应用提供了参考。     

进口原羊毛携带有害生物情况及检疫监管模式探讨

通过对进口原羊毛进行研究分析,认为其可携带许多种动物病原、植物有害生物、病原微生物、害虫、媒介生物以及粪便等,具有携带率高、隐蔽性强、难以预测等特点,会给我国动植物和人类健康造成威胁,也会给我国农畜产品的出口造成严重影响。针对当前检验检疫工作任务较重、人力不足、标准体系不完善、监管难度加大等方面的实际情况,提出需建立包括加工厂注册登记、开展风险分析和分类管理、现场查验、后续监管、提升能力和完善体系等内容的检疫监管模式。     

中药制剂产后康复宁的药理研究

应用ＬＭＳ－２Ｂ二道生理记录仪及配套装置,通过免疫器官重量法和鸡红细胞（ＣＲＢＣ）作免疫原的溶血素（ＩｇＭ）测定法及体内抑菌试验法,观测了中药制剂产后康复宁对家兔离体、在位子宫和小鼠免疫功能的影响,以及对感染大肠杆菌Ｋ８８小鼠的保护作用。结果表明,产后康复宁可使兔离体子宫收缩频率显著增加（Ｐ＜０．０１）,张力显著增强（Ｐ＜０．０１）,振幅显著增高（Ｐ＜０．０１）;与麦角相比,仅５ｍｉｎ相同时间的子宫收缩频率差异明显（Ｐ＜０．０５）,其余相同时间子宫收缩频率、张力、振幅均无明显差异（Ｐ＞０．０５）。使在位子宫收缩频率明显增加（Ｐ＜０．０５）,张力明显增强（Ｐ＜０．０５）,振幅明显增高（Ｐ＜０．０５）;与麦角比较,子宫收缩频率、张力、振幅在５、１０ｍｉｎ相同时间内差异均不明显（Ｐ＞０．０５）。对免疫功能的影响,不但使小鼠脾脏显著增重（Ｐ＜０．０１）,而且溶血素明显增多（Ｐ＜０．０５）。对感染大肠杆菌Ｋ８８的小鼠有明显的保护作用（Ｐ＜０．０５）。提示产后康复宁有增强子宫收缩,促使宫内恶露排除,加速子宫复旧,增强机体免疫功能等作用。     

Heat stress-induced mucosal barrier dysfunction is potentially associated with gut microbiota dysbiosis in pigs

Heat stress(HS)can be detrimental to the gut health of swine.Many negative outcomes induced by HS are increasingly recognized as including modulation of intestinal microbiota.In turn,the intestinal microbiota is a unique ecosystem playing a critical role in mediating the host stress response.Therefore,we aimed to characterize gut microbiota of pigs’exposure to short-term HS,to explore a possible link between the intestinal microbiota and HS-related changes,including serum cytokines,oxidation status,and intestinal epithelial barrier function.Our findings showed that HS led to intestinal morphological and integrity changes(villus height,serum diamine oxidase[DAO],serum D-lactate and the relative expressions of tight junction proteins),reduction of serum cytokines(interleukin[IL]-8,IL-12,interferongamma[IFN-g]),and antioxidant activity(higher glutathione[GSH]and malondialdehyde[MDA]content,and lower superoxide dismutase[SOD]).Also,16S rRNA sequencing analysis revealed that although there was no difference in microbial a-diversity,some HS-associated composition differences were revealed in the ileum and cecum,which partly led to an imbalance in the production of short-chain fatty acids including propionate acid and valerate acid.Relevance networks revealed that HS-derived changes in bacterial genera and microbial metabolites,such as Chlamydia,Lactobacillus,Succinivibrio,Bifidobacterium,Lachnoclostridium,and propionic acid,were correlated with oxidative stress,intestinal barrier dysfunction,and inflammation in pigs.Collectively,our observations suggest that intestinal damage induced by HS is probably partly related to the gut microbiota dysbiosis,though the underlying mechanism remains to be fully elucidated.