Prototheca zopfii genotype 2: the causative agent of bovine protothecal mastitis?

In order to clarify the epidemiology of bovine protothecal mastitis, 30 Prototheca zopfii mastitis isolates were genetically investigated. Based on the 18S rDNA, which allows a differentiation of the former species P. zopfii in two distinct P. zopfii genotypes and Prototheca blaschkeae sp. nov., newly developed genotype-specific PCR-assays as well as RFLP-assays were applied.

All mastitis isolates investigated could be assigned to P. zopfii genotype 2 suggesting that this genotype is the aetiological agent of bovine Prototheca mastitis.     

Re-challenge of pigs following recovery from proliferative enteropathy

An experimental challenge model was developed to demonstrate Lawsonia intracellularis colonization and reproduction of proliferative enteropathy (PE) in naïve weaner pigs. Groups of pigs were orally dosed with between 10¹⁰ and 10⁵ L. intracellularis extracted from haemorrhagic PE affected mucosa. Pigs were monitored for clinical signs and intestinal lesions of PE and evidence of bacterial colonization by serology and faecal polymerase chain reaction (PCR). One group of challenged pigs were necropsied after 21 days to confirm the reproduction of PE. L. intracellularis colonization and seroconversion was delayed in pigs dosed with lower numbers of L. intracellularis. When faecal shedding of L. intracellularis ceased to be detected in all of the challenged pigs, they were re-dosed orally with approximately 10¹⁰ L. intracellularis and monitored for evidence of re-colonization and clinical disease. This study demonstrated that pigs previously challenged with L. intracellularis were protected from re-colonization and clinical disease on subsequent exposure 10 weeks later, regardless of the initial dose of L. intracellularis.     

Detection of Ehrlichia muris DNA from sika deer (Cervus nippon yesoensis) in Hokkaido, Japan

Ehrlichia muris DNA was detected in the blood of sika deer (Cervus nippon yesoensis) by species-specific PCR based on the citrate synthase gene, which was shown to be more sensitive than species-specific PCR based on the 16S rRNA gene. Among 102 deer examined, one deer was positive. Deer may be a possible mammalian reservoir of E. muris.     

莲藕施肥机无轴双螺旋供肥装置性能分析与试验

针对藕田施肥过程中存在的劳动强度高、施肥稳定性及均匀性较低的问题,设计了一种水力喷射式莲藕施肥机,其主要分为供肥装置和水肥混合装置,主要对无轴双螺旋供肥装置进行了设计与分析。通过理论分析确定影响供肥性能参数主要为螺旋转速、直径和导程,结合藕田施肥农艺要求确定上述3项参数的取值范围。利用EDEM对无轴双螺旋供肥性能进行离散元仿真分析,以供肥量均值和供肥量稳定性变异系数为评价指标分别进行单因素试验和回归正交旋转组合试验。单因素试验结果表明：供肥量均值随着螺旋转速、直径和导程的增大而增大,并且具有良好的线性关系,因此可通过调节供肥螺旋转速、直径和导程来改变供肥量均值;供肥量稳定性变异系数随着螺旋转速和导程的增大呈现先降低后升高的趋势,而随着直径的增大而减小。运用Design-Expert软件对回归正交旋转组合试验结果进行分析优化,分别开展仿真试验和台架试验对优化后的参数进行验证。结果表明,当螺旋转速为160 r·min^-1,螺旋直径为78 mm,螺旋导程为53 mm时,仿真结果供肥量均值为329.43 g·s^-1,供肥量稳定性变异系数为1.43%,...     

刀切法在森林双重回归抽样调查中的应用初探

为进一步 改进抽样 效果, 将 刀切法 结 合顺 序统 计 量应 用于 双 重回 归抽 样 中, 以 材 积为目的因 子, 胸径 为辅助因 子。结果 表明, 在 减少 二重 样本 ５０ ％ 的情 况下 , 与 普通 双重 回 归抽样相比 , 精度仍 达９８２ ％ 。因 此认为, 在林 相整 齐, 生长 正常 的 林分 中进 行 双重 回归 抽 样调查时, 利 用刀切法 , 可 在减 少 二重 样 本, 减少 外 业工 作 量 的情 况 下, 仍能 保 持 较 高 的精 度。另外, 对二重样 本单元和 单元数 的确定以 及刀切 法的局限 性进行了 讨论。     

Real-time spectral classification of compression wood inPicea abies

Compression wood is formed by the living tree to compensate for external loads. It creates wood fibers with properties undesirable in sawn products. Automatic detection of compression wood can lead to production advantages. A wood surface was scanned with a spectrometer, and compression wood was detected by analyzing the spectral composition of light reflected from the wood surface within the visible spectrum. Linear prediction models for compression wood in Norway spruce (Picea abies) were produced using multivariate analysis and regression methods. The resulting prediction coefficients were implemented in a scanning system using the MAPP2200 smart image sensor combined with an imaging spectrograph. This scanning system is capable of making a pixelwise classification of a wood surface in real time. Classification of one spruce plank was compared with analysis by scanning electron microscopy, showing that the automatic classification was correct in 11 of 14 cases.     

温度周年变化与桑树植原体消长的关系

通过聚合酶链反应检测了植原体在桑树体内的分布及其相对含量的周年变化。结果显示,茎部中植原体的含量在生长季节逐渐升高,７月达到最大,而冬季检测不到,叶部与茎部相似但植原体的含量在８月达到最大;根部全年均含有植原体,含量较低。     

RFLP analysis of a PCR amplified region of chloroplast DNA in eggplant and related Solanum species

RFLP analysis of a PCR amplified 3.2-kbp region of cpDNA bounded by the conserved sequences in rbc L and ORF 106 was performed in eggplant (Solanum melongena), its related Solanum species, S. incanum, S. virginianum (= S. surattense), S. torvum, S. aethiopicum (= S. gilo), S. aethiopicum (= S. integrifolium), S. violaceum (= S. indicum), S. violaceum (= S. sanitwongsei) and S. mammosum and the reciprocal hybrids between S. aethiopicum (= S. integrifolium) and S. melongena 'Uttara'. The target region of cpDNA was amplified correctly by PCR. The amplified products were digested with each of 10 restriction enzymes (Alu I, Ase I, BamH I, Hinf I, Msp I, Rsa I, ScrF I, Sty I, Taq I and Xba I). Variations of restriction patterns among the species were recognized after digesting the amplified products with each of the seven restriction enzymes, Taq I, Alu I, Rsa I, Sty I, Ase I, Hinf I and Xba I. The restriction patterns divided the examined nine species into the following five clusters, 1) S. melongena and S. incanum, 2) S. virginianum (= S. surattense), 3) S. torvum, 4) S. aethiopicum (= S. gilo), S. aethiopicum (= S. integrifolium), S. violaceum (= S. indicum) and S. violaceum (= S. sanitwongsei) and 5) S. mammosum. The restriction pattern with Alu I in each of the reciprocal hybrids between S. melongena 'Uttara' and S. aethiopicum (= S. integrifolium) was identical with that of seed parent. The present study demonstrated the availability of the PCR-RFLP analysis of cpDNA for assessing taxonomic relationships and identifying cytoplasmic parentage of interspecific hybrids in eggplant and related Solanum species. This revised version was published online in July 2006 with corrections to the Cover Date.     

龙眼和荔枝染色体DNA的提取与鉴定

以龙眼“大乌圆”和荔枝“三月红”两个品种的幼叶和果实组织为试材 ,采用在细胞核被裂解之前 ,去除细胞质中的酚类物质和蛋白质 ,而后用 SDS裂解细胞核 ,异丙醇和乙醇沉淀染色体 DNA的方法 ,成功地从两种不同组织中提取和纯化了两种果树的染色体 DNA,DNA的得率介于 2 86～ 314μg/g FW之间 ,凝胶电泳显示无明显降解现象 ,适宜作为 PCR模板应用 ,并成功地进行特异性基因扩增