Effects of liming on organic matter decomposition and phosphorus extractability in an acid humic Ranker soil from northwest Spain

Summary A laboratory incubation experiment was carried out over 17 weeks to determine the effect of liming on soil organic matter. The amount of lime as calcium hydroxide [Ca(OH)₂] required to completely neutralise exchangeable Al was found to be five times the standard lime requirement. This large amount of lime had a limited overall effect on the short-term stability of soil organic matter, causing the release of 1300 g g^-1 of C (1.7% total soil C) above the control during the incubation. Liming may have altered the potential availability of soil organic matter and organic P, as shown by a marked reduction in the extractability of soil organic P with sodium bicarbonate and sodium hydroxide. The latter was unlikely to be due to the formation of calclium-P artefacts, and may be attributed to the combined chemical effects of added calcium hydroxide and precipitation of exchangeable Al on the nature and solubility of soil organic constituents and organomineral complexes. The addition of lime increased the degradation of added oak leaf litter by 50%, from 3.2 to 4.7 mg g^-1, as determined by CO₂ evolution. The enhanced litter degradation indicated increased microbial activity in limed soil, but this improvement had only minor effects on the stability of native organic matter. This study highlights the need for further research into the relationships between the chemical nature of organic P in soil and the physical, chemical, temporal, and agronomic factors that control its turnover and availability.     

湖南小鹅瘟防治研究 Ⅰ.小鹅瘟实验室诊断

本文报道了小鹅瘟实验室诊断(包括病原分离、血清保护试验及血清中和试验)的结果,表明引起湖南省部分地区雏鹅死亡的病原为小鹅瘟病毒。     

猪附红细胞体病并发弓形虫病的诊治

[目的]诊断吉林省延边州某养猪场发病原因。[方法]对病猪的临床症状和病理剖检变化进行了观察,采集血液样本进行病原学检测和抗体检测,提取病猪的组织与血液DNA进行PCR分子生物学检测。[结果]根据临床症状、病理剖检变化以及实验室检测结果,确诊为猪附红细胞体病与弓形虫病混合感染。采取血呼平和速复欣拌料给药,并结合附红血注射液肌注给药的中西医结合的方式进行治疗,取得了满意的效果。[结论]该研究可为猪场类似疾病的诊治提供依据。     

Causes of Encephalitis and Encephalopathy in Brazilian Equids

The etiology of diseases that affect the central nervous system (CNS) of equids was investigated. Samples (n = 218) collected from equids showing clinical signs of nervous or behavioral changes were analyzed, of which 37 (17.0%) were positive for rabies, 13 (6.0%) for the presence of protozoans (one Sarcocystis neurona, 12 Toxoplasma gondii), three (1.4%) for equine herpesvirus type 1 myeloencephalopathy, and 24 (11%) for bacterial encephalitis. Histopathology of the CNS revealed one (0.4%) case of cryptococcal myelomeningoencephalitis and 20 (9.2%) cases of equine leukoencephalomalacia. Central nervous system samples were positive for Sarcocystis neurona and Toxoplasma gondii by nested PCR-ITS1 followed by nucleotide sequencing. Diagnosis of equine herpesvirus 1 was confirmed by cell isolation and polymerase chain reaction followed by sequencing of the GD and polymerase (ORF 30) genes in three samples. No case of equine encephalomyelitis was diagnosed in samples analyzed by isolation in mice, VERO cell cultures, and RT-PCR for the nsP1 gene. Bacterial agents (Staphylococcus spp., Streptococcus spp., Bacillus spp., Enterobacteriaceae spp., Corynebacterium spp., and nonfermenting gram-negative bacillus) were detected in pure or preponderant cultures. Diagnosis was conclusive in 45% of samples, indicating that other infectious and noninfectious etiologies of encephalitis and encephalopathy should be considered for investigation.     

猪血凝性脑脊髓炎实验室诊断方法综述

猪血凝性脑脊髓炎是引起仔猪神经系统障碍的重要传染病之一,严重危害养猪业健康发展。正确诊断猪血凝性脑脊髓炎对防治该病极为关键。文章围绕该病病原分离鉴定、血清学诊断、分子生物学诊断这三方面研究进展分别展开阐述,以期了解该病诊断方面的研究进展。     

An unusual type of malathion-carboxylesterase in a Japanese strain of house fly

It had been reported that a Japanese multiple-resistant strain of house fly, Hirokawa, had a high malathion-carboxylesterase activity as well as a normal level of esterase activity to α-naphthylacetate (NA). This is different from the situation in several other malathion-resistant strains, where high malathion-carboxylesterase activity goes together with a low level of activity to α-NA. This had been explained by the so-called “mutant ali-esterase theory,” which assumed that the opposite changes in activity to malathion and α-NA were the result of one and the same change in an ali-esterase. In the Hirokawa strain the esterase degrading malathion seems to be responsible for about 64% of the activity to α-NA. This was concluded since the two activities were equally sensitive to denaturation and to two organophosphorus inhibitors. Moreover activity of malathion was inhibited by α-NA, and that of α-NA by malathion. Most of the latter activity was inhibited competitively. Inhibition of activity to malathion was lower, however, than to be expected on the basis of competitive mutual inhibition. This case of resistance to malathion therefore seems to involve a different kind of “mutant ali-esterase” than in other strains. Increased hydrolysis of the insecticide seems to be achieved without loss of activity to α-NA, although K_m is different. The strain further showed an unusually high β-NA hydrolysis and malaoxon-carboxylesterase activity (about 3- and 200-fold, respectively, that of another malathion-resistant strain G).     

高校实验室设备管理程序探讨

高校的仪器设备是进行实验教学和科研工作的必备条件。仪器设备管理水平直接影响着其使用效益,影响着实验教学和科研工作的水平。因此,必须重视高校仪器设备的科学管理,从各个环节细微之处入手,把仪器设备的管理作为高校管理工作的重点之一。     

防治香蕉假茎象甲的常用药剂室内药效试验

采用虫体浸液法测定了17种常用杀虫剂对香蕉假茎象甲的室内药效,在参试的杀虫剂中,毒死蜱、丙溴辛硫磷、联苯菊酯、敌敌畏、三唑磷、甲氨基阿维菌素苯甲酸盐的效果较好,药后3d,防效分别达到100%、100%、86.97%、80.91%、80.00%。药后7d,药效较高的杀虫剂为联苯菊酯、敌敌畏、甲维盐、乙酰甲胺磷和甲维.丙溴磷,其中联苯菊酯和敌敌畏的药效分别为96.97%和80.91%,甲维盐、乙酰甲胺磷和甲维.丙溴磷的药效均为80.00%;辛硫磷、敌百虫、乐果、丁硫克百威、阿维菌素、鱼藤酮氰戊、吡虫啉、茚虫威、多杀霉素和高效氯氰菊酯等10种杀虫剂对香蕉假茎象甲的药效均较低。     

农业工程实验室运行管理模式研究---以南京农业大学工学院为例

以我院农业电气化、农业机械化及其自动化两个国家一流本科专业建设点相继获批为契机，学院教改团队对农业工程相关专业的教学大纲、教学方法、课程实验、创新能力训练等实践教学任务进行改革，并结合农业工程实验室实际情况，经过不断的探索和实践，在实验教学中心形成了“学生为本、强化基础、注重能力、促进创新、提高素质”的全过程管控的实验教学模式。经实践证明，这种管理模式有利于实践教学管理和实验设备维护，在实验室管理实践中取得了良好效果。