Carbon and nitrogen dynamics in ageing earthworm casts in grasslands of the eastern plains of Colombia   总被引：5，自引：0，他引：5  

T. Decaëns  A. F. Rangel  N. Asakawa  R. J. Thomas 《Biology and Fertility of Soils》1999,30(1-2):20-28

 The effects of a large species of anecic earthworm, Martiodrilus carimaguensis Jiménez and Moreno, on soil C and N dynamics were investigated in a native savanna and a man-made pasture of the eastern plains of Colombia. We compared, across time (11 months), the total C, total N, NH⁺ ₄ and NO^– ₃ contents in the earthworm casts, the underlying soil and the adjacent soil. Additional sampling of root biomass and macrofauna was performed. In the two management systems, the total C and N contents were higher in casts (4.33–7.50%) than in the bulk soil (2.81–4.08%), showing that the earthworms selected food substrates with high organic contents. In general, C contents significantly increased during cast ageing (+100%), possibly because of CO₂ fixation processes, dead root accumulation and/or macrofaunal activities in casts. In fresh casts, NH⁺ ₄ levels were very high (294.20–233.98 μg g^–1 dry cast) when compared to the soil (26.96–73.95 μg g^–1 dry soil), due to the intense mineralisation processes that occurred during the transit of soil and organic matter through the earthworm gut. During the first week of cast ageing, NH⁺ ₄ levels sharply decreased, while NH^– ₃ levels showed successive peaks in the casts, the underlying soil and the adjacent soil. These results suggested the rapid production of NO^– ₃ by nitrification processes in the fresh casts, followed by diffusion to the nearby soil, first vertically, then horizontally. After 2 weeks of cast ageing, NH⁺ ₄ and NO^– ₃ levels only showed slight variations, likely because of organic matter protection in stable dry casts. The root biomass was higher (1.6–4.7 times) below the old earthworm casts. The ecological significance of these results is discussed. Received: 22 October 1998  相似文献   

Life cycle inference and phylogeny of Ortholinea labracis n. sp. (Myxosporea: Ortholineidae), a parasite of the European seabass Dicentrarchus labrax (Teleostei: Moronidae), in a Portuguese fish farm          下载免费PDF全文

L F Rangel  S Rocha  G Casal  R Castro  R Severino  C Azevedo  F Cavaleiro  M J Santos 《Journal of fish diseases》2017,40(2):243-262

Ortholinea labracis n. sp. is described and its life cycle is inferred from a Southern Portuguese fish farm, with basis on microscopic and molecular procedures. This myxosporean parasite infects the urinary bladder of the European seabass Dicentrarchus labrax and the intestinal epithelium of a marine oligochaete of the genus Tectidrilus. Myxospores subspherical in valvular view and ellipsoidal in sutural view measuring 7.6 ± 0.3 (6.8–8.7) μm in length, 7.2 ± 0.2 (6.7–7.7) μm in width and 6.5 ± 0.4 (5.8–7.7) μm in thickness. Two polar capsules, 3.0 ± 0.2 (2.6–3.4) μm long and 2.4 ± 0.1 (2.0–2.9) μm wide, located at the same level, but with divergent orientation and opening to opposite sides of the suture line. Sequencing of the SSU rRNA gene revealed a similarity of 100% between the analysed myxospores and triactinomyxon actinospores. The phylogenetic setting of O. labracis n. sp. shows subgrouping in correlation with tissue tropism, but identifies this parasite as another exception to the main division of Myxosporea into the main freshwater and marine lineages.  相似文献   

海兰灰蛋鸡患输卵管囊肿对屠宰性能、器官指数、血清生化指标及组织病理学的影响     

敖蕊  许晨远  朱崇淼  姚文  郑卫江 《畜牧兽医学报》2022,53(3):990-998

本试验旨在研究海兰灰蛋鸡患输卵管囊肿对屠宰性能、器官指数、血清生化指标及组织病理学的影响.选取同一饲养环境下的54周龄海兰灰蛋鸡16只,分为对照组(CTR,n=9)和输卵管囊肿组(CFT,n=7)进行屠宰并采集血清样品,测定蛋鸡屠宰性能、器官指数和血清生化等指标.结果表明:1)输卵管囊肿组蛋鸡的活重和屠体重较对照组极显...  相似文献   

嗜水气单胞菌感染翘嘴鳜头肾转录组分析          下载免费PDF全文

朱鑫海  张紫瑞  周丽颖  汤环宇  敖士齐  周一凡  高晓建  姜群  张晓君 《渔业科学进展》2022,43(4):208-217

嗜水气单胞菌(Aeromonas hydrophila)是严重危害翘嘴鳜(Siniperca chuatsi)养殖生产的主要病原之一,为揭示嗜水气单胞菌感染翘嘴鳜后宿主基因表达水平的变化,筛选免疫相关基因,解析翘嘴鳜应答病原细菌感染的分子机制,本研究以病原嗜水气单胞菌感染翘嘴鳜,于感染24 h后,采集感染组与对照组翘嘴鳜头肾组织,采用Illumina Hiseq 2000进行了RNA-Seq分析,原始数据拼接后组装共获得53 040个单基因(unigene)。基因差异表达分析结果显示,感染组和未感染组翘嘴鳜存在526个差异表达基因,包括254个上调基因和272个下调基因,其中,免疫相关的显著上调的差异基因主要有炎症和免疫原性细胞因子白介素、补体系统、MHCⅠ型抗原提呈、溶菌酶、丝氨酸蛋白酶抑制因子、泛素蛋白连接酶等。GO富集分析发现,差异基因主要涉及免疫应答反应和炎症反应等,经KEGG富集分析显示,89个通路富集显著,免疫相关的代谢通路主要有内吞作用和吞噬体等。此外,实时荧光定量PCR验证结果表明,所选取7个差异表达免疫相关基因与RNA-seq结果具有相似的表达趋势。本研究为揭示翘嘴鳜对病原微生物感染的防御分子机制奠定了理论基础。  相似文献   

The decline of fisheries on the Madeira River,Brazil: The high cost of the hydroelectric dams in the Amazon Basin          下载免费PDF全文

Rangel E. Santos  Ricardo M. Pinto‐Coelho  Rogério Fonseca  Nadson R. Simões  Fabrício B. Zanchi 《Fisheries Management and Ecology》2018,25(5):380-391

Despite being considered beneficial by providing a clean and renewable source of energy, the construction of hydroelectric dams has extremely negative implications for Amazonian fisheries. This study investigated the impacts of the Santo Antônio and Jirau hydroelectric dams on the fishery stocks of the Madeira River. This investigation was based on fish catch data from the Z‐31 fishing colony, located in the municipality of Humaitá, in Amazonas State, Northern Brazil. Data were collected daily and provided information on the date of return from each trip, the fish species targeted, and the total catch (kg) between January 2002 and September 2017. The results indicated reductions of 39% in the mean annual catch and 34% in the mean monthly catches. These results highlight the high price paid by local fish communities for the development of hydroelectric power in the Amazon basin.  相似文献   

无乳链球菌不同途径感染吉富罗非鱼后病原菌在体内的分布规律研究     

甘西  蒋和生  罗永巨  谭芸  敖秋桅  罗伟  沈夏霜  朱佳杰 《淡水渔业》2018,(4):76-80

为探讨无乳链球菌(Streptococcus agalactiae)感染罗非鱼(Oreochromis spp)的致病途径。采用腹腔注射、灌胃和浸泡三种方式对吉富罗非鱼进行无乳链球菌(HN016菌株)胁迫感染,利用平板活菌计数法统计三种方式感染后病原菌在体内组织的分布。注射和灌胃两种方式感染后均出现典型的链球菌感染发病症状,其中注射组在感染24 h后出现死亡高峰,死亡率为92.5%;灌胃组感染48 h后出现死亡高峰,死亡率为90%;而浸泡组,感染后均没有出现明显的发病症状,也没有出现死鱼。注射组和灌胃组在感染后2 h,其脾脏、肝脏、前肾、胃、腮、皮肤和肌肉组织中均可分离出病原菌,5 h后在脑组织中均可分离出病原菌,8 h后各组织分离出的病原菌数达到峰值;而浸泡组在感染8 h后才从各组织中分离出病原菌,且它们的数量均低于同时期的注射组和灌胃组。注射和灌胃两种方式可使吉富罗非鱼快速感染无乳链球菌而发病,而浸泡方式感染后病原菌虽可以侵入机体,但不表现出症状。由此,我们推测在自然条件下养殖的罗非鱼是通过口腔采食携带无乳,链球菌的食物而被感染。  相似文献   

分子印迹固相萃取-高效液相色谱法测定牛奶中四环素类抗生素残留     

付珍珍  曾月  李增威  何利  周康  刘书亮  邹立扣  敖晓琳  陈姝娟 《浙江农业学报》2018,30(2):314

采用分子印迹技术合成四环素类分子印迹聚合物,以其为填料制备固相萃取柱,运用高效液相色谱法测定牛奶中的四环素类抗生素。具体地,以盐酸强力霉素为模板分子、甲基丙烯酸为功能单体、乙二醇二甲基丙烯酸酯为交联剂,采用沉淀聚合法在丙酮-乙腈混合溶液中制备具有特异性吸附能力的分子印迹聚合物,通过高效液相色谱仪检测其吸附四环素类抗生素的能力,并将其作为填料制备固相萃取柱,用于牛奶中四环素类抗生素残留检测。结果显示,四环素类抗生素在0.05~10.0 μg·mL^-1范围内线性良好,加标回收率为79.4%~86.3%,相对标准偏差均小于3.8%,准确性较好。四环素和土霉素的检出限为0.02 μg·mL^-1,金霉素的检出限为0.05 μg·mL^-1,检测灵敏度高,特异性识别能力强。  相似文献   

6个桃新品种引进种植试验     

金方伦  黎明  韩成敏  张发维  敖学熙 《天津农业科学》2016,(4):112-118

6个引进的桃新品种在本地区试种,能够正常开花结果。于2012—2015年调查各品种的物候期、植物学特性、经济性状和抗逆性等内容进行比较。结果表明:6个桃品种在当地科学管理条件下,表现好的品种有新川中岛和艳红桃等2个品种,其树势表现为较强和强,萌芽率为55.82%和55.81%,成枝率为28.39%和23.26%,叶片大小为17.1 cm×4.2 cm和19.5 cm×5.0 cm,花的大小为4.8 cm×4.7 cm和4.8 cm×4.9 cm,座果率为43.19%和26.66%,成熟期为7月中下旬和7月下旬—8月上旬,平均单果质量为195.5 g和216.9 g,含糖量为13.5%和15.8%,单株产量为41.3 kg和43.1 kg,果实可食率为94.35%和93.81%,都表现为适应性强。从综合比较结果看,新川中岛品种表现最好,其次是艳红桃品种,由此建议在当地自然资源条件下加上配套的栽培技术措施,新川中岛和艳红桃2个品种可在本地区适量发展。  相似文献   

外来植物豚草入侵对土壤碳氮转化的影响     

刘小文  何福林  齐成媚  全沁果  敖艳  李园  骆鹰  颜冬冬  曹坳程 《浙江农业学报》2016,28(2):297

选取撂荒田地为试验样地,以入侵植物豚草（Ambrosia artemisiifolia L.）为对象,以土著优势物种窃衣（Torilis scabra Thunb.）为参照,通过对入侵植物和土著植物根际土壤的采样分析,研究了入侵植物对入侵地土壤特性及土壤碳氮转化的影响。结果表明,与土著物种窃衣相比,豚草入侵使土壤有机质含量增加89.13%,全氮含量增加42.15%,铵态氮含量增加43.69%,硝态氮含量增加35.36%,微生物量碳增加52.08%,微生物量氮增加61.26%,氮净矿化速率增加1.41倍,氮净氨化速率增加206倍,但硝化速率和反硝化速率变化不明显。由此可见,豚草显著改变了入侵地土壤的理化特性,加速了土壤碳氮转化过程。  相似文献   

通辽市塞外红苹果桃小食心虫发生规律观察及防治药剂筛选试验     

敖特根  周宇利  张嘉益  沈彦彬  陈顺 《林业科技》2022,47(1):40-42

2018～2020年,在开鲁县塞外红苹果园系统观察了桃小食虫发生规律,并开展了防治药剂筛选试验.结果表明:桃小食心虫在通辽地区大多数果园出现较晚,1代/年,少部分果园2代/年,全年发生相对集中,整个发生期历时3个多月,成虫最早出现在6月下旬,但数量较少,连续出现在7月中旬,7月下旬到8月上旬为高蜂期,8月中下旬进入盛末...  相似文献