Youssoufenes A2 and A3, Antibiotic Dimeric Cinnamoyl Lipids from the ΔdtlA Mutant of a Marine-Derived Streptomyces Strain

Two new dimeric cinnamoyl lipids (CL) featuring with an unusual dearomatic carbon-bridge, named youssoufenes A2 (1) and A3 (2), were isolated from the ΔdtlA mutant strain of marine-derived Streptomyces youssoufiensis OUC6819. Structures of the isolated compounds were elucidated based on extensive MS and NMR spectroscopic analyses, and their absolute configurations were determined by combination of the long-range NOE-based ¹H-¹H distance measurements and ECD calculations. Compounds 1 and 2 exhibited moderate growth inhibition against multi-drug-resistant Enterococcus faecalis CCARM 5172 with an MIC value of 22.2 μM.     

南方水稻籼改粳与“青森5号事件”——20世纪50年代发生的一起重大引种事故

建国初期,各级政府习惯用战争年代开展"群众运动"的做法指导农业生产,"青森5号事件"是一起典型的违反科学规律和自然规律、不尊重科学家意见,盲目引种造成水稻大面积减产事例。《人民日报》发表社论,针对北种南移、远程调运造成减产的问题,批评在种子工作中存在的盲目调种、急于求成、强迫命令现象。最后由政府承担了"盲目引种"造成损失的责任。"青森5号事件"催生了农作物品种区域试验制度,以及"自繁、自选、自留、自用,辅之以调剂"(通称为"四自一辅")种子工作方针。     

细胞色素C氧化酶的纯化及动力学性质研究

采用硫酸铵分级沉淀和CytochromeC -Sepharose 4B亲和层析 ,从牛心线粒体中纯化了细胞色素C氧化酶 (CytochromeCOxidase ,简称CCO ) ,其比活性为 1 7 88s- 1 ·mg- 1 ,聚丙烯酰胺凝胶电泳为一条带 ,血红素A (HemeaA)含量达到 1 5 4nmol/mg。纯化后的CCO具有典型的CCO特征 ,还原态CCO峰值出现在 60 5nm和 443nm ,氧化态CCO峰值出现在 598nm和 42 4nm。CCO的稳态动力学参数Vm1、Km1、Vm2 、Km2 分别为 1 42s- 1 、 0 53μmol/L、 2 71s- 1 、 1 81 μmol/L。     

基于机器视觉的嫁接用苗外观特征自动检测

提出了基于数学模型的幼苗外观特征自动检测方法,检测项目包括生长状态、子叶参数和胚轴参数。首先经过图像预处理提取幼苗二值图,利用行像素统计图确定特征参数基准点位置。然后以标定胚轴最小矩形倾斜度和宽度判定弯曲状态;子叶跨度通过两子叶端点距离确定,子叶展开角通过两子叶底端平展位置拟合线夹角判定;胚轴弯曲度通过胚轴中心线上曲率最大的位置为分界点分别判断两段斜度而求得,胚轴长、轴径结合斜度补偿求得。与手工测量数据对比,轴长、轴径和子叶跨度的相关系数分别为0.935 1、0.899 9和0.903 4,相对误差分别小于7%、5%和7%,绝对误差分别小于4 mm、0.2 mm和6 mm。     

中国种业人力资源大流动评议

据有关部门资料，2000年时，全国县级以上种子公司有2700多家，委托代销公司约55000多家。《中华人民共和国种子法》(以下简称《种子法》)施行两年后，全国种子产业大分化、大联合的局面初显端倪。据有关资料，全国注册资金3000万元以上种子企业已超过60家，注册资金500万元以上的种子公司近万家，委托代销公司可能在10万家以上。     

兔病毒性出血症首免时间的研究

针对生产上出现的从断奶育成这一年龄段多发兔病毒性出血症的实际情况，采用快速、敏感的Dot-ELISA方法，通过测定不同免疫状态下的母兔所产兔的母源抗体动态变化规律，并进一步测定不同抗体效价的成年兔攻毒后是否得到保护的结果，再结合生产实际，得出兔病毒性出血症首免时间为30日龄，且剂量加倍。     

Effect of Fermentation Bed with Spent Mushroom Substrate of Pleurotus eryngii on Weaning Piglets

[Objective] The paper was to investigate effects on fermentation bed temperature,growth performance,diarrhea rate and digestive en-zyme activity of weaning piglets by using spent mushroom substrate of Pleurotus eryngii as padding.[Method] A total of 120 weaning piglets(Duroc × Landrace ×Yorkshire) with average initial body weight of(8.0 ±0.5)kg were allocated to five dietary treatments in a randomized complete block design for 42 d,each of which was replicated three times with eight piglets per replicate(half male,half female).The padding for control group was(50% sawdust +50% rice husk);experimental group Ⅰ 100% spent mushroom substrate;experimental group Ⅱ(15% sawdust +15% rice husk +70% spent mushroom substrate);experimental group Ⅲ(25% sawdust +25% rice husk +50% spent mushroom substrate);experimental group Ⅳ(35% sawdust +35% rice husk +30% spent substrate).[Result] There was no significant difference in surface temperature of fermentation bed between experimental groups and control group(P0.05).Compared with the control group,the temperature under 20 cm of fermentation bed in ex-perimental groups I,Ⅱ and Ⅲ increased significantly(P0.05).Except for experimental group Ⅳ,other three experimental groups had higher aver-age daily gain(P0.05) and experimental group Ⅰ had higher average daily feed intake(P0.05) compared to the control group.The diarrhea rate and mortality of weaning piglets in experimental groups Ⅱ,Ⅲ and Ⅳ were significantly decreased compared with the control group(P0.05).Compared with the control group,other three experimental groups had higher digestive enzyme activity in duodenal contents except for experimental group Ⅳ(P0.05).[Conclusion] Spent mushroom substrate of P.eryngii can be used as fermentation bed padding,and the optimal proportion was experimental group Ⅲ.     

Research on the Antioxident Function of Sulforaphane on the Leydig Cells of Cadmium Exposured Mice

The study was aimed to explore the antioxident function of sulforaphane (SFN) on the leydig cells of cadmium (Cd) exposured mice.Cd and SFN were added to the cell culture medium of TM3 cell, half inhibitory concentration (IC₅₀) of Cd and SFN safe dose range were determined.The tested model was set up,and the relative survival rate of TM3 cells, lactate dehydrogenase (LDH) activity and cell antioxidant levels were determined to study the antioxident function of SFN to cadmium exposured mice.The results showed that:①With the increase of Cd concentration,the relative survival rate of TM3 cells was decreased,and the IC₅₀ of Cd was 51.4 μmol/L;Within a certain concentration range,SFN could increased the cells survive rate,but there was toxicity when the SFN concentration was more than the scope,and the greater the concentration,the greater the toxicity. At experimental condition,SFN safety concentration were 2.5,5 and 10 μmol/L.②Compared with the control group,the GSH content,the T-SOD and GSH-Px activities in Cd group were significantly or extremely significantly decreased (P < 0.05;P < 0.01),and the LDH activity,the MDA content were increased.Additionally,the LDH activity and MDA content of SFN groups were decreased,while others three indexes were increased. Compared with Cd group,the GSH content,the T-SOD and GSH-Px activities of Cd+SFN groups were significantly or extremely significantly increased (P < 0.05;P < 0.01),however,the LDH activity,MDA content were decreased. The result indicated that SFN had the antagonism effect on toxicity of Cd in TM3 cell.     

Seroepidemiology and genotyping of hepatitis E virus in Singapore reveal rise in number of cases and similarity of human strains to those detected in pig livers

Hepatitis E virus (HEV) causes 20 million infections worldwide yearly, of which only about 3.3 million are symptomatic. In developed Asian countries, HEV strains detected in human sera and in food sources were genetically similar, suggesting that indigenous HEV infections may be largely food‐borne. To assess the burden of hepatitis E in Singapore, we performed a seroepidemiologic study of the infection. Additionally, we carried out HEV genotyping on archived, residual HEV IgM‐positive serum samples collected between 2014 and 2016 (n = 449), and on pig liver samples (n = 36) purchased from wet markets and supermarkets. Our study shows a rise in hepatitis E incidence (IgM) from 1.7 to 4.1 cases per 100,000 resident population from 2012 to 2016 and an increase in hepatitis E IgG positivity rate among residents from 14% in 2007 to 35% in 2016. Other findings also suggest the epidemiology of hepatitis E in Singapore has shifted, from it being mainly a disease imported from the Indian subcontinent, to one that is now increasingly prevalent in our resident population. Genotypes obtained from 143 human samples identified the majority to be genotype 3 (n = 121), 21 to be genotype 1 and one to be genotype 4. Further phylogenetic analyses suggest genotype 3a to be the cause of indigenous infections in residents, which showed genetic similarity to the genotype 3a strains detected in pig livers. This link between the strains in the majority of human samples and those in pig livers consumed by the public suggests a possible food‐borne route of HEV infection in Singapore.     

1株犬副流感病毒的分离鉴定及生物学特性研究

试验旨在分离鉴定犬副流感病毒(canine parainfluenza virus,CPIV),并对其生物学特性进行研究。用Vero细胞接种感染CPIV阳性犬肺脏组织,盲传4代,收集72 h病毒液进行RT-PCR鉴定、电镜观察、血凝试验、热敏性试验、紫外照射试验及病毒一步生长曲线的测定,同时扩增N基因进行序列分析,并构建系统进化树。结果显示,试验成功从出现咳嗽、流鼻涕等呼吸系统疾病症状的病犬肺脏中分离出1株CPIV,命名为CPIV-BJ01;RT-PCR扩增结果发现,在534 bp处有特异性目的条带。病毒电镜观察发现,其超微结构呈圆形、有囊膜、直径在80～200 nm之间;血凝试验显示,病毒在4和37℃均能凝集1%猪红细胞,与报道的CPIV血凝特性一致;病毒对热敏感,长时间高温下病毒毒价会随之下降;紫外照射可使病毒在短时间内对细胞的感染性急剧下降。病毒一步生长曲线测定结果显示,在12～48 h病毒高速增殖,细胞培养液中病毒滴度急剧上升,之后趋于稳定。CPIV N基因序列与19株有代表性的副流感病毒N基因相比,其核苷酸序列同源性为97.1%～99.8%。遗传进化分析表明,CPIV-BJ01与PIV5 1168-1(登录号:KC237064.1)和PIV5 ZJQ 221(登录号:KX100034.1)位于同一分支上,亲缘关系较近。