Simultaneous Flow Cytometric Analysis of Phagocytosis and Oxidative Burst Activity in Equine Leukocytes

This paper describes a method for simultaneously measuring phagocytosis and oxidative burst activity in equine peripheral blood leukocytes by flow cytometry. Opsonized propidium iodide-labelled Staphylococcus aureus (PI-Sa) was used to measure the uptake of bacteria by equine phacocytes and the oxidative burst activity by oxidation of dihydrorhodamine 123. The requirements to achieve optimal activity of phagocytosis and oxidative burst are described. The advantage of the simultaneous technique is that it provides both independent and comparative values for phagocytosis and the oxidative burst, for the detection of impaired mechanisms of microbial destruction. Furthermore, the technique allows evaluation of opsonization activity in this context.     

Molecular Characterization and Diagnosis of QoI Resistance in Cucumber and Eggplant Fungal Pathogens

ABSTRACT The molecular mechanism of QoI fungicide resistance was studied using isolates of cucumber Corynespora leaf spot fungus (Corynespora cassiicola) and the eggplant leaf mold (Mycovellosiella nattrassii). In both pathogens, a mutation at position 143 from glycine to alanine (G143A) was detected in the cytochrome b gene that encodes for the fungicide-targeted protein. Moreover, the nucleotide sequence at amino acid position 143 was converted from GGT or GGA in sensitive (wild-type) to GCT or GCA in resistant (mutant-type) isolates. The methods of polymerase chain reaction restriction fragment length polymorphism commonly used for QoI resistance monitoring were employed successfully, leading to the amplified gene fragment from resistant isolates being cut with the restriction enzyme ItaI. However, heteroplasmy (the coexistence of wild-type and mutated alleles) was found when the resistant isolates of C. cassiicola, M. nattrassii, and Colletotrichum gloeosporioides (strawberry anthracnose fungus) were subcultured in the presence or absence of QoI fungicides. QoI resistance of cucumber powdery and downy mildew isolates persisted for a few years following the removal of the selection pressure imposed by the fungicide under both laboratory and commercial greenhouse conditions. The proportion of mutated sequences in cytochrome b gene decreased over time in the pathogen population. The protective efficacy of the full dose of azoxystrobin decreased when the populations of powdery and downy mildews contained resistant isolates at 10%. Using FMBIO, a fluorescence bio-imaging analyzer, the mutant allele from the QoI-resistant isolates could be detected at the level of 1%, whereas the detection sensitivity of ethidium-bromide-stained gels was approximately 10 times lower.     

花生栽培种的染色体组——1.推断染色体组供体的细胞遗传学研究

在包括着花生栽培种在内的花生属同一区系中野生二倍体种的细胞学研究表明,除一个种外,其染色体组型具有9对大染色体和1 对小染色体(‘A’)的特征。例外的一个种A.ba tizocoi具有更为一致的染色体组型。相同染色体组型二倍体种的种间杂种,具有中等的至高的花粉染色率,但在包含着A.batizocoi的杂交组合中,其杂种的花粉染色率为0,花粉母细胞的减数分裂也很不规则。这种不育的杂种,通过染色体组加倍,很可能产生可育的、稳定的双二倍体。有人提议,栽培种花生可能起源于这样一种不育的种间杂种,而从形态学和植物地理学角度来看,截至目前所搜集到的类型,最可能的染色体组的供体种是A.cardenasii和A.batizocoi。     

一种测定猪饲料蛋白质表观消化率的尼龙袋新技术

测定家畜饲料营养份可消化率,需要大量饲料和为时较长的日粮适应期(Schneider和platt,1975)。但如将饲料样本人为导入消化道,并于粪中无损失地回收未消化的材料,则可克服上述弊端。早期记载的有关绵羊的研究是经口投入塞有青草的多孔金属小管(de Reaumur,1756)。1782年,Spallanzani自己吞入装有面包和肉的亚麻布     

公猪和采精频率对母猪受胎率和胚胎存活率的影响

公猪的年龄和采精频率对精液品质影响很大。采精频率对受精力的影响,过去报道很少。拉德福(Radford,1961)建议,未成熟的公猪每隔4天采精一次,成熟的公猪每周采2—3次。丹羽(Niwa,1961)认为,间隔5—6天最好,但精力旺盛的公猪可以每天采精一次。卡洛尔等人(Carroll,1962)建议,九月龄公猪的配种次数每天不要超过一次。母猪排卵的数量,同品种(纯种或杂种)、近亲的程度、配种时的年龄、配种和产仔时的     

大豆斑疹病疱斑形成过程的电镜观察

 由(Xanthomonas campestris pv.glycines)所致大豆斑疹病病斑隆起成疱。盆栽大豆感病品种(Chippewa和Horosoy)和它们的抗病品系在二片真叶展开2/3时,用高压喷雾接种(Xanthomonas campestris pv.glycines),接种后的第3、6、9天分别取样;样本分二种处理分别在扫描电镜、透射电镜和普通光学显微镜下观察病斑形成过程.接种后3天,肉眼可见褪绿斑时,病斑部分的表皮细胞和薄壁细胞组织已开始膨大,病斑部分稍有隆起.第6天,肉眼能见疱斑时,表皮细胞和薄壁细胞膨大明显,少数细胞开始破裂.第9天病斑开始变褐,电镜下可见疱斑完全破裂,表皮细胞和薄壁细胞膨大数倍于正常细胞,且细胞破裂,大量细菌溢出。同时可以看到大豆斑疹病细菌在发病初期是在细胞间隙中存活和繁殖的,在表皮细胞和薄壁细胞破裂后进入细胞内,最后完全破坏细胞.从电镜切片中也可以看到疱斑形成主要是由于细胞体积增大所致.抗病品种只有褪绿斑,渐变褐,肉眼看不见疱斑,但在电镜下可见得下表皮稍隆起,有少数细菌存在于细胞间隙,未见有细菌溢出现象。     

水稻品种苗期阶段对白叶枯病的抗性研究

 根据水稻品种各叶期对白叶枯病的抗性表现和强弱程度可分为四类:(1)全期抗病型;(2)全期中抗型;(3)苗感成株抗病型;和(4)全期感病型。可以看出,水稻品种除少数苗感成抗型外,其余三种抗性类型苗期与成株期的抗性反应是一致的。由于中抗、成抗和感病品种各叶期的抗性有随着叶位的升高而抗性增强的趋势,不同抗性品种在苗期阶段抗感对比均较成株期明显。因此,水稻品种对白叶枯病的抗性鉴定采用苗期鉴定方法是可行的。影响水稻品种苗期抗性的因素是:苗龄(叶期)、观察时期、品种与菌株的组合等。     

一种由麦二叉蚜和麦长管蚜传播的小麦黄矮病毒株系的鉴定

 通过对采自我国内蒙古丰镇县13个春小麦病株标样进行4种蚜虫连续传毒比较,不同温度饲毒和接种试验,薄膜饲毒,2种蚜虫成若蚜传毒比较和血清学酶标试验等,明确我国内蒙古丰镇县小麦黄矮病毒株系为由麦二叉蚜和麦长管蚜有效传播的麦二叉蚜麦长管蚜株系(GAV)。对于这个株系,禾缢管蚜与玉米蚜是不能传播的。这种株系在我国冬麦区春麦区都有分布。     

拟除虫菊酯能够对付抗药性的挑战吗?

拟除虫菊酯是一组杀虫剂,介绍的应用范围很广。可是,已存在一个潜在的严重危机,因为已报道对拟除虫菊酯产生抗药性的节肢动物种数从1967年的几种上升到了70多种,包括已经对其它化学杀虫剂产生极强抗药性的主要害虫,且这种情况将会由于过度施药而加重。因此,有必要寻找延缓抗药性产生和发展的策略。节肢动物抗拟除虫菊酯的报道数量比经济上防治失败的事例要多。因为:(a)在极