Identification and functional characterization of brainstem cannabinoid CB2 receptors

The presence and function of CB2 receptors in central nervous system (CNS) neurons are controversial. We report the expression of CB2 receptor messenger RNA and protein localization on brainstem neurons. These functional CB2 receptors in the brainstem were activated by a CB2 receptor agonist, 2-arachidonoylglycerol, and by elevated endogenous levels of endocannabinoids, which also act at CB1 receptors. CB2 receptors represent an alternative site of action of endocannabinoids that opens the possibility of nonpsychotropic therapeutic interventions using enhanced endocannabinoid levels in localized brain areas.     

SOS response induction by beta-lactams and bacterial defense against antibiotic lethality

The SOS response aids bacterial propagation by inhibiting cell division during repair of DNA damage. We report that inactivation of the ftsI gene product, penicillin binding protein 3, by either beta-lactam antibiotics or genetic mutation induces SOS in Escherichia coli through the DpiBA two-component signal transduction system. This event, which requires the SOS-promoting recA and lexA genes as well as dpiA, transiently halts bacterial cell division, enabling survival to otherwise lethal antibiotic exposure. Our findings reveal defective cell wall synthesis as an unexpected initiator of the bacterial SOS response, indicate that beta-lactam antibiotics are extracellular stimuli of this response, and demonstrate a novel mechanism for mitigation of antimicrobial lethality.     

Robinson B: Attack autotomy: a defense against predators

The response of five species of crabs to simulated predator attack was examined. Two terrestrial species autotomized their chelipeds after the chelae were firmly attached to the predator. Selection for attack autotomy is balanced by selection for retention of the cheliped whenever the cheliped is important in social or maintenance functions.     

H2S: a universal defense against antibiotics in bacteria

Many prokaryotic species generate hydrogen sulfide (H(2)S) in their natural environments. However, the biochemistry and physiological role of this gas in nonsulfur bacteria remain largely unknown. Here we demonstrate that inactivation of putative cystathionine β-synthase, cystathionine γ-lyase, or 3-mercaptopyruvate sulfurtransferase in Bacillus anthracis, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli suppresses H(2)S production, rendering these pathogens highly sensitive to a multitude of antibiotics. Exogenous H(2)S suppresses this effect. Moreover, in bacteria that normally produce H(2)S and nitric oxide, these two gases act synergistically to sustain growth. The mechanism of gas-mediated antibiotic resistance relies on mitigation of oxidative stress imposed by antibiotics.     

猴头菌CB1染料脱色及其相关木质素降解酶的研究

[目的]探索猴头菌CB1木质素降解酶系统对4种染料脱色降解的研究。[方法]采用紫外/可见分光光度计,检测猴头菌木质素降解酶活性及4种染料不同浓度的脱色率。[结果]猴头菌可同时产生Mn P和Laccase,但不产生Li P。随着Mn2+的浓度变化,Mn2+对Mn P的酶活性起到诱导/限制作用;猴头菌在72 h对不同浓度的茜素红和中性红染料的脱色率分别为100.00%和68.75%,而5 mg/L浓度的刚果红在24 h的最大脱色率为74.61%,5 mg/L结晶紫在72 h的最大脱色率为66.86%。[结论]猴头菌的胞外酶液对不同浓度的茜素红和中性红染料表现为易脱色底物,刚果红次之,结晶紫最难被脱色降解。     

Hot air treatment activates defense responses and induces resistance against Botrytis cinerea in strawberry fruit

The effect of hot air(HA, 45°C, 3.5 h) treatment on reducing gray mold caused by Botrytis cinerea in strawberry fruit and the possible mechanisms were investigated. The results showed that HA treatment significantly reduced lesion diameter and enhanced activities of chitinase(CHI), β-1,3-glucanase and phenylalanine ammonia-lyase(PAL) in strawberry fruit. Total phenolic contents were also increased by HA treatment. The activities of antioxidant enzymes including superoxide dismutase(SOD), catalase(CAT) and ascorbate peroxidase(APX) were higher in HA treated strawberry fruit than those in control. Expression of three defense related genes such as CAT, CCR-1 allele and PLA6 was greatly induced in HA treated strawberry fruit with or without inoculation by B. cinerea. In addition, the in vitro experiment showed that HA treatment inhibited spore germination and tube growth of B. cinerea. These results suggested that HA treatment directly activated disease resistance against B. cinerea in strawberry fruit without priming response and directly inhibiting growth of B. cinerea.     

核孔蛋白Atnup98-like降低拟南芥对细菌和干旱的抗性

用HrpNEa处理拟南芥(Arabidopsis)时发现核孔蛋白AtlG59660基因的表达被抑制.因该基因编码的蛋白质与哺乳动物中的核孔蛋白(nucleoporin98)具有相似性质,具有FG(phenylalanine-glycine)重复基序,故命名为Atnup98-like.同时对野生型和Atnup98-like突变体植株分别进行病原细菌Psyringae syringae pv.tomato DC3000接种及干旱处理,结果发现突变体植株对DC3000的抗性明显增强,而且突变体中抗病相关基因PR1a的表达明显强于野生型;同时,突变体植株比野生型植株抗旱性增强,脯氨酸含量明显升高,且干旱诱导的效应基因RD29B的表达水平强于野生型.上述结果表明,核孔蛋白基因Atnup98-like的突变增强了拟南芥对DC3000和干旱的抗性,因此,其可能是拟南芥抗性反应中一个重要的负向调节因子.     

植原体分类研究进展

目的明确云南元谋地区发生的萝卜花变叶病病原以及赤霉素合成途径中关键酶基因表达量的变化。方法对自然表现花变叶、丛枝和节间缩短的萝卜感病植株总DNA进行植原体16S rRNA基因扩增、克隆、测序及系统进化树构建,并采用实时荧光定量PCR技术分析赤霉素合成及代谢途径中关键酶基因(GA20ox1、GA3ox1和GA2ox1)表达量的变化。结果该植原体株系与16SrII-A亚组相似性最高(0.98),并与16SrII-A亚组中的其他植原体株系明显形成一个进化支。结论萝卜花变叶植原体(Raphanus sativus phyllody,RsPh-YNym)为植原体16SrII-A亚组成员,且与候选种Candidatus Phytoplasma aurantifolia相关,明确了该株系的分类地位;感病植株茎中3种关键酶基因GA20ox1、GA3ox1和GA2ox1表达水平发生了变化,表达量均下调,说明植原体的侵染造成了植株赤霉素稳态被破坏,从而导致植株表型改变。     

大豆异黄酮对健康大鼠肝脏CB1R、FAAH、DGAT1表达的影响

【目的】研究大豆异黄酮(Soy isoflavone,SIF)对大鼠肝脏中大麻素1型受体(CB1R)、脂肪酰胺水解酶(FAAH)和二脂酰甘油酰基转移酶(DGAT1)表达的影响,为SIF活性的研究与应用提供参考。【方法】试验选取40只6周龄SD大鼠,随机分为正常组和低、中、高剂量组,每组10只,分别按0,50,250,500mg/kg的剂量经口灌胃含SIF的羧甲基纤维素钠溶液4周后,麻醉,采血收集血清,全自动生化仪进行血液生化指标检测。解剖大鼠取肝脏组织制备石蜡切片,HE染色进行病理分析,油红O检测脂滴沉积情况,免疫组织化学、实时荧光定量PCR(以β-actin为内参基因)分别对CB1R、FAAH、DGAT1蛋白及其基因进行定量分析。【结果】与对照组相比,SIF低剂量组总胆固醇浓度显著下降(P0.05);中剂量组总胆固醇、甘油三酯和低密度脂蛋白浓度显著下降(P0.05);高剂量组总胆固醇和低密度脂蛋白浓度极显著下降(P0.01)。各组大鼠肝脏组织学结构正常,均未见异常病理变化。SIF中、高剂量组肝脏脂滴沉积极显著减少(P0.01)。与对照组相比,SIF低剂量组大鼠肝脏中FAAH蛋白的表达量显著增多(P0.05),中、高剂量组CB1R、FAAH和DGAT1蛋白表达量均极显著增多(P0.01)。与对照组相比,SIF低剂量组大鼠肝脏CB1R、FAAH、DGAT1 mRNA表达量均显著降低(P0.05),中、高剂量组CB1R mRNA表达量显著增多(P0.05),高剂量组FAAH mRNA表达量极显著增多(P0.01)。【结论】SIF可影响肝脏内CB1R、FAAH、DGAT1的表达,且存在明显的剂量差异。     

PS04菌株对水稻纹枯病的防效及对水稻2种防御性酶活性的诱导

【目的】研究类芽孢杆菌PS04菌株及其代谢物对水稻纹枯病的预防和治疗效果,探索PS04对水稻纹枯病的防治机理,为PS04菌株生物制剂的研发提供理论依据。【方法】以水稻幼苗为供试材料,用带菌谷粒接种法接种水稻纹枯病菌,分别以PS04菌株发酵液、浓缩液和乙醇粗提物为药剂,保护性试验于接种前24h施药,治疗性试验于接种后24h施药,施药10d后调查统计防效;同时喷施发酵液与接种水稻纹枯菌进行防御性酶诱导试验,分别于接种后1,2,3,5,8d测定水稻叶鞘过氧化物酶(POD)和多酚氧化酶(PPO)活性,并分析其动态变化。【结果】药效试验表明,PS04菌株发酵液兼具保护性和治疗性作用,其防效分别达93.65%和92.02%,经100℃水浴加热后发酵液的防效分别为87.37%和90.28%;PS04浓缩液和乙醇粗提物的保护性和治疗性防效均具有明显的剂量效应,6g/L浓缩液的防效为76.01%和50.74%,9g/L乙醇粗提物的防效69.95%和73.85%。防御性酶活性诱导试验表明,PS04菌液能诱导水稻PPO和POD活性大幅提高,表明PS04发酵液具有良好的抗病性诱导作用。【结论】PS04菌液不仅对水稻苗期纹枯病具有显著的保护性和治疗性,而且还能诱导水稻POD和PPO活性提高,具有很好的开发潜力。     

偏肿革裥菌系统发育与Lg-mnp2和Lg-mnp3基因克隆及结构特征

白腐菌偏肿革裥菌Lenzites gibbosa能分泌降解木质素的锰过氧化物酶(MnPs),为进一步鉴定试验菌株,对菌株L. gibbosa CB1进行了ITS序列(Gen Bank登录号为JF279440)扩增与测序,并进行了基于ITS序列的比对与系统发育分析,结果表明CB1与桦革裥菌L. betulina和栓菌属Trametes等相关白腐菌的亲缘关系较近而聚类在一起,并与24个同种其他菌株的ITS序列覆盖度在85%～97%期间内的相似性都为99%,说明该菌株为偏肿革裥菌。为了获得该菌株多个编码MnP家族的基因,从而为研究MnP基因的表达调控奠定序列结构的基础,根据已知白腐菌MnPs基因保守区和已经扩增出的基因片段设计引物,以L. gibbosa CB1的基因组DNA和总RNA为模板,采用PCR、RT-PCR、RACE及染色体步移等方法,克隆到该菌株编码MnP2和MnP3的全长c DNA和DNA基因(Gen Bank登录号分别为JQ388597、JN571114; JQ411249、JN571116),分别命名为Lg-mnp2和Lg-mnp3。2个基因DNA全长分别为2 869、3 992 bp,都含有6个外显子和5个内含子;其启动子区域都含有TATA-Box、CAAT-Box、AP2、MRE等顺式作用元件,Lg-mnp2还含有AP1,Lg-mnp3还含有HSE;其c DNA基因分别含有50、52 bp的5'UTR,150、249 bp的3'UTR和1098、1 101 bp的完整开放阅读框ORF,分别编码了365、366个氨基酸的蛋白质多肽前体(Gen Bank登录号分别为AFC37493、AFC37494),成熟的Lg-mnp2蛋白含有339个氨基酸,比Lg-MnP1蛋白(Gen Bank登录号为ACO92620)多1个氨基酸;成熟的Lg-mnp3蛋白含有340个氨基酸,比Lg-MnP2蛋白多1个氨基酸。     

Blockade of N-methyl-D-aspartate receptors may protect against ischemic damage in the brain

In rats ischemia of the forebrain induced by a 30-minute occlusion of the carotid artery, followed by 120 minutes of arterial reperfusion, produced ischemic lesions of selectively vulnerable pyramidal cells in both hippocampi. Focal microinfusion into the dorsal hippocampus of 2-amino-7-phosphonoheptanoic acid, an antagonist of excitation at the N-methyl-D-aspartate-preferring receptor, before ischemia was induced protected against the development of ischemic damage. It is proposed that excitatory neurotransmission plays an important role in selective neuronal loss due to cerebral ischemia.     

Viral infection and host defense

Double-stranded RNA, made as an intermediary substance in the replication of most, if not all, viruses, may play a much more important role in the pathogenesis and the recovery from virus infections than has hitherto been suspected. Apparently, dsRNA is used by both the challenge virus and the host cell in an attempt to gain "molecular control." Double-stranded RNA exerts a set of effects, which may be well balanced, not only at the level of the individual cell but also at the complex assemblage of these cells termed the organism (Fig. 1). In the cell, interferon synthesis is triggered, although interferon mRNA translation may not occur if dsRNA shuts off protein synthesis too quickly. In the whole organism, the disease severity will depend on how certain toxic reactions evoked by infection (such as cell necrosis and fever) are counterbalanced by an increase in the host defense mechanisms (for example, immune responsiveness and interferon production). Many aspects of the response, relating to either progress of, or recovery from, the disease, can be explained on the basis of a dsRNA. In addition to drawing attention to the biodynamic role of dsRNA, our hypothesis suggests specific experimental vectors designed to enhance our information on the molecular basis of the morbid process which occurs with viral infection. Finally, we suggest that, although the dsRNA molecule may be viewed as a rather simple unit structure, the opportunity for further diversity in the biological activity of a given dsRNA molecule always exists. Namely, each deviation from a perfectly double-helical arrangement introduces the possibility for emphasizing one biological reactivity at the expense of another. This latter structure-activity property may partially account for the extreme apparent diversity, commonly encountered, in the presentations of virologic illness. Appendix note added in proof. Subsequent to submission of this text, we have found that the potent mitogen effect of dsRNA for lymphocytes (murine and human) is also exquisitively sensitive to the fidelity in base pairing of the input polymer pair (59). For example, infrequent "loops" (one nucleotide per 20 base pairs) in an otherwise perfectly helical rI(n) (.) rC(n) molecule [for example, rI(n) (.) r(C(19,)U)(n)] strongly changes its mitogenic properties. This observation, which supports our thesis that a "fine structure" term can be developed for other reactions triggered by dsRNA's in biological systems, emphasizes that diverse biological effects may be encountered with an ostensibly uniform family of dsRNA's.