Characterisation of energy-dependent efflux of imazalil and fenarimol in isolates of Penicillium italicum with a low,medium and high degree of resistance to DMI-fungicides

Differential accumulation of [¹⁴C]imazalil and [¹⁴C]fenarimol by germlings of wild-type and DMI-resistant isolates ofPenicillium italicum was studied at various pH values. At pH 7 and 8 the low-resistant isolate E_300–3 accumulated 22% and 35%, respectively, less imazalil than the wild-type isolate W₅. Imazalil accumulation at pH 5 and 6 was similar. Isolate E_300–3 also accumulated less fenarimol as compared with the wild-type isolate. This difference was much more obvious than for imazalil and was observed at all pH values tested. Differences in accumulation of both imazalil and fenarimol between low (E_300–3), medium (H₁₇) and high resistant (I₃₃) isolates were not observed. These results suggest that decreased accumulation of DMIs is responsible for a low level of resistance only and that additional mechanisms of resistance might operate in isolates with a medium and high degree of resistance. With all isolates fenarimol accumulation was energy-dependent. This was not obvious for imazalil.The wild-type and DMI-resistant isolates had a similar plasma membrane potential as determined with the probe [¹⁴C]tetraphenylphosphonium bromide ([¹⁴C]TPP⁺). Various test compounds, among which ATPase inhibitors, ionophoric antibiotics and calmodulin antagonists, affected the accumulation of [¹⁴C]TPP⁺, [¹⁴C]imazalil and [¹⁴C]fenarimol. No obvious correlation between the effects of the test compounds on accumulation levels of the fungicides and [¹⁴C]TPP⁺ could be observed. These results indicate that the plasma membrane potential does not mediate the efflux of DMI fungicides byP. italicum.     

枯草芽孢杆菌（Bacillus subtilis）S9对植物病原真菌的溶菌作用

本研究共分离了976株细菌分离物，发现来自甘蔗根围的1株枯草芽孢杆菌(Bacillus subtilis)S9对立枯丝核菌(Rhizoctonia solani)、终极腐霉(Pythium ultimum)和西瓜枯萎病菌(Fusarium oxysporum f.sp.niveum)在PDA平板的对峙培养过程中不形成抑菌圈，但4d后可使上述植物病原真菌的菌丝溶解。扫描电镜观察发现S9菌株在待测的立枯丝核菌表面形成了溶菌斑。S9菌株对立枯丝核菌的作用过程是通过吸附在病原真菌的菌丝上，并随菌丝生长而生长，而后产生溶菌物质消解菌丝体。液体共培养测定也证明了S9菌株具有上述作用。本研究还发现，S9菌株对植物病原真菌的拮抗真菌绿色木霉(Trichoderma viride)、鲜红毛壳菌(Chaetomium cupreum)和球毛壳菌（Chaetomium globosum）的生长没有影响。盆栽试验证明了S9菌株可有效地控制立枯丝核菌(R．solani)引起的番茄苗期病害。S9菌株与其它拮抗真菌混合具有促进防治植物病原真菌引起的植物病害的潜力。     

花刺参钙调蛋白cDNA克隆及组织分布

钙调蛋白（ calmodulin,CaM）是一种钙离子（ Ca2＋）结合蛋白,在钙信号传导过程中起重要作用。文章扩增到花刺参（Stichopus monotuberculatus）钙调蛋白（命名为StmCaM）cDNA全长序列。StmCaM cDNA全长1394 bp,其中5＇UTR长138 bp,3＇UTR长806 bp,ORF为450 bp。ORF推导出的StmCaM含149个氨基酸（包含起始蛋白酸）,其预测分子量约为16.7 kDa,理论等电点为4.1。StmCaM氨基酸序列与其他物种的钙调蛋白高度相似,相似度百分比为95.9%~98.0%。采用realtime PCR分析StmCaM基因在花刺参不同组织中的表达,结果显示其在呼吸树中表达量最高,体腔细胞、肠次之,而体壁中表达量最低,几乎检测不到。     

‘鸭梨’钙调素基因的克隆与表达分析

以‘鸭梨’为材料,用RT-PCR及RACE技术克隆CaM,并借助实时定量PCR技术分析‘鸭梨’花、叶及果实不同发育时期的表达模式,获得了2个长度为764和801bp的CaM cDNA序列,分别命名为PbCaM1和PbCaM2,二者均含有450bp完整开放阅读框,编码149个氨基酸,且氨基酸序列相同。‘鸭梨’CaM在系统进化上具有高度保守性,与苹果相比,两者氨基酸序列为100%一致性。PbCaM1和PbCaM2具有时空表达特异性,它们在成叶、盛花期花瓣和幼果期表达量较高。本研究表明CaM具有高度保守性,PbCaM1和PbCaM2在‘鸭梨’果实早期生长发育过程中起着非常重要的作用。     

Ca~(2 )对芒果果实后熟效应的研究

以７～８成熟的芒果果实为材料,比较果实减压渗钙与否对后熟的效应,研究与果实后熟相关酶类的活性和钙调蛋白（ＣａＭ）含量的动态变化,寻找它们之间的相互关系。结果表明：对照果实或者Ｃａ２＋处理果实在后熟过程中,ＣａＭ含量均发生变化,与此同时,伴随着多聚半乳糖醛酸酶（ＰＧ）、淀粉酶（Ａｍｇｌａｓｅ）活性的变化,它们之间存在极显著的相关性。Ｃａ２＋对果实后熟具有双重效应,当Ｃａ２＋处理果实置于室温下时,ＣａＭ含量、ＰＧ、淀粉酶活性明显受到抑制,后熟延缓。但把Ｃａ２＋处理果实冷藏（１２ ｄ）后回至室温第 ３～４ ｄ时,或直接减压渗钙果肉切片,其ＣａＭ含量、ＰＧ、淀粉酶活性增加,后熟加快。外源乙烯能解除Ｃａ２＋的抑制效应。并讨论了Ｃａ２＋的这些效应的可能机制。     

大豆胞囊线虫病的生防因子研究进展

综述了大豆胞囊线虫的各类生防因子,如食线虫真菌、食线虫细菌、杀线虫植物、捕食性线虫和捕食性土壤动物等,其中研究较深入的是食线虫真菌和细菌,食线虫真菌可归纳为5种类型,即捕食性真菌、专性内寄生菌物、机会真菌、产毒真菌和菌根菌;另外,还对其他生防因子的最新研究结果进行了归类综述,并对大豆胞囊线虫的生物防治进行了展望。     

Muscarinic Receptors in Equine Airways

The distribution of muscarinic receptors in equine airways was investigated using autoradiography. Frozen sections of tissue from six different levels in the bronchial tree, from the trachea to the distal bronchioles, were incubated in vitro with 1.5 nmol/L of the muscarinic receptor antagonist 1-[N-methyl-³H]scopolamine methyl chloride (³H-NMS). In addition, the subtype pattern of muscarinic receptors was investigated in equine tracheal smooth muscle using radioligand binding with methoctramine, tripinamide, 4-DAMP-methiodide and pirenzipine as competitors against the binding of 1.3 nmol/L ³H-NMS. The autoradiograms showed specific labelling indicating a high density of muscarinic receptors in smooth-muscle tissue in all levels of the airway tree investigated. Besides muscle tissue, subepithelial glands were the only structures specifically labelled. The dominating subtypes in tracheal smooth muscle investigated with radioligand binding studies were found to be M₂ and M₄, as both methoctramine (pK _d = 8.5) and tripinamide (pK _d = 8.6 and 6.7 for two different sites) showed high affinity. The density of the M₃-muscarinic receptor subtype was low, but this subtype could be detected with statistical significance when methoctramine was used as the competitor against ³H-NMS binding.     

Effects of 4-hydroxytamoxifen on the growth and proliferation of prolactinomas CH3 cells

AIM: To investigate the effect of estrogen antagonists on the in vitro growth of human prolactinomas. METHODS: RT-PCR was applied to the detection of estrogen receptor (ER) mRNA expressed in a human prolactinomas CH3 cell strain. Estradiol and 4-hydroxytamoxifen (OHTam) were added respectively at different concentrations into the culture medium. Cell number and levels of ER mRNA were examined. RESULTS: The growth of CH3 cells became slower in estrogen-deprived medium than that in nomal culture and was higher in medium containing estrogen(E2) at concentration of 10^-8 mol/L than at concentration of 10^-6 mol/L. OHTam (10^-6mol/L) inhibited the growth of CH3 cell strain treated with E2. The expression of ER mRNA in CH3 cells was observed, the levels of ER mRNA in the E2 (10^-8mol/L) group, higher than those in estrogen deprived group. OHTam (10^-6mol/L) obviously inhibited the expression of ER mRNA. CONCLUSION: The growth of CH3 cells depends on estrogen, estrogen antagonists inhibits the growth of CH3 cells and decline the levels of ER mRNA. ER levels in human prolactinomas cell lines can be auto-regulated.     

Advances in the application of neuropeptides in insect control

The development of a new approach for the generation of a novel type of putative insect control agents based on backbone cyclic peptidomimetic antagonists of insect-neuropeptides is reported. The approach, termed the backbone cyclic neuropetide based on autogonist (BBC-NBA) was applied to the insect pyrokinin/pheromone biosynthesis activating neuropeptide (PBAN) family as a model, and led to the discovery of a potent linear lead antagonist and several highly potent, metabolically stable BBC peptidomimetic antagonists, devoid of agonistic activity, which inhibited in vivo PBAN-mediated activities in moths.