褪黑素对谷氨酸钠致痫大鼠脑内一氧化氮含量的影响

目的观察褪黑素(Melatonin,MT)对谷氨酸钠致痫大鼠脑内一氧化氮(nitric oxide,NO)含量的影响,研究其抑制癫痫的作用机制。方法40只健康雄性SD大鼠随机分为4组(每组10只):生理盐水对照组(NS组);谷氨酸钠致痫组(Glu组);褪黑素+谷氨酸钠组(MT+Glu组);Luzidole+褪黑素+谷氨酸组(Luz+MT+Glu组)。观察大鼠行为变化,记录脑电图,用NADPH组织化学反应检测大鼠海马内NO含量变化。结果行为学观察和EEG显示,NS组无痫样发作和痫样放电,Glu组和Luz+MT+Glu组痫样发作重(Ⅲ-Ⅴ级),脑电图显示频发高幅的痫样波,MT+Glu组有轻微发作(0-Ⅱ级),脑电图上偶见散在单个微小痫样波;NADPH组织化学反应结果显示,Glu组和Luz+MT+Glu组大鼠大脑皮质及海马内NOS阳性细胞与对照组比较增多,差异性明显(P<0.05),MT+Glu组较Glu组和Luz+MT+Glu组内NOS阳性细胞减少,差异性明显(P<0.05)。结论MT对谷氨酸钠致痫大鼠痫样发作程度、痫样放电有抑制作用,其机制之一是经其特异性受体,减弱NO作用,进而发挥抑痫效应。     

褪黑素对谷氨酸钠致痫大鼠海马5-羟色胺水平的影响

目的观察褪黑素(Melatonin,MT)对谷氨酸钠(Glutamate,Glu)致痫大鼠海马5-羟色胺(5-hydroxytryptamine,5-HT)水平的影响,研究其抑制癫痫的作用机制。方法40只健康雄性SD大鼠随机分为4组(每组10只),分别为生理盐水对照组(NS组);谷氨酸钠致痫组(Glu组);褪黑素 谷氨酸钠组(MT Glu组);Luzidole 褪黑素 谷氨酸钠组(Luz MT Glu组)。观察并记录大鼠行为学及脑电图改变,用免疫组织化学方法检测大鼠海马内5-HT含量变化。结果行为学观察和EEG显示,NS组无痫样发作和痫样放电,Glu组和Luz MT Glu组痫样发作重(Ⅲ-Ⅴ级),脑电图显示频发高幅的痫样波,TM Glu组无或仅有轻微发作(0-Ⅱ级),脑电图上无或偶见散在单个微小痫样波;免疫组织化学分析结果显示,Glu组和Luz MT Glu组大鼠海马内5-HT含量与对照组比较均减少,差异性明显(P<0.05),MT Glu组较Glu组和Luz MT Glu组5-HT含量升高,差异性明显(P<0.05)。结论MT对谷氨酸钠致痫大鼠痫样发作程度、痫样放电有抑制作用,其机制之一是经由其特异性的膜受体,通过某种机制增强5-HT作用,进而发挥抑痫效应。     

MT1过表达可通过抑制PI3K/AKT/mTOR信号通路影响SKOV3细胞的增殖与凋亡

卵巢癌是一种常见的威胁女性健康的恶性肿瘤。然而卵巢癌的发生机制尚不清楚。该研究旨在探讨褪黑激素受体MT1在人卵巢癌SKOV3细胞中的作用及其主要机制。采用MT1-pcDNA3.1质粒(MT1组)与空载体pcDNA3.1(对照组)转染SKOV3细胞,未转染SKOV3细胞作为阴性对照组。转染48 h后,新鲜培养基培养24 h或48 h,观察细胞周期、增殖、凋亡情况,上清液检测褪黑激素表达。此外,在血清缺乏培养基培养细胞并转48 h后,更换新鲜培养基并加入4 μmol/L PF-04691502抑制剂孵化24 h。测定AKT蛋白水平、总mTOR蛋白水平和相应磷酸化蛋白水平。结果显示,与NC组相比,MT1组在细胞周期S期阻滞(P0.05),伴随增殖减少和早期凋亡(P0.05)。3组细胞上清液检测到褪黑激素分泌均随时间增加(P0.05)。Western blot分析显示,MT1过表达抑制了PI3K/AKT/mTOR信号通路的激活。该研究得出,SKOV3细胞有自行分泌褪黑激素的能力。MT1过表达可与内源性褪黑激素结合,抑制PI3K/AKT/mTOR信号通路的激活,最终发挥抗癌作用。     

褪黑素对FSH诱导的小鼠卵母细胞体外成熟的影响

通过次黄嘌呤(HX)阻滞、FSH诱导体外培养模型研究了褪黑素(MT)对小鼠卵母细胞成熟的影响,探讨褪黑素(MT)是否影响小鼠卵母细胞的体外成熟。0.1mg/mL和0.02mg/mL两有效浓度的MT能显著抑制促性腺激素(FSH)诱导的HX阻滞的CEOsGVBD的发生(P<0.05),对PBl的排出虽有一定的抑制作用,但没有统计学意义;MT和次黄嘌呤(HX)对CEOs的自发成熟有协同抑制作用(P<0.01),但在裸卵(DO)自发成熟的阻滞中没有协同效应。MT是调节哺乳动物卵母细胞成熟的重要激素之一,其作用机制可能是通过卵丘细胞实现的。     

MicroRNA与癫痫的研究进展

癫痫是大脑神经元高度同步化异常放电所导致的短暂的大脑功能障碍的一种慢性疾病。癫痫的发病原因十分复杂,目前主要治疗方式是药物治疗,但仍然有30%左右的难治性癫痫患者依靠药物治疗未能控制癫痫发作,因此从分子角度研究癫痫的发病机制及治疗是近年来癫痫研究的热点。微小RNA(miRNA)在癫痫患者及癫痫动物模型海马组织中存在差异性表达,通过抑制miRNA的差异表达在一定程度上可以缓解癫痫的症状,这为癫痫的治疗开辟了新的途径和方向。因此随着miRNA与癫痫相关性研究深度的不断加深,有望能够为癫痫的诊断及治疗提供一个全新的思路。     

褪黑素对谷氨酸致痫大鼠海马内谷氨酸、GABA及其受体水平的影响

目的探讨褪黑素(melatonin,MT)对谷氨酸(glutamate,Glu)致痫大鼠海马内Glu及GluR2、γ-氨基丁酸(γ-aminobutyric-acid,GABA)及其受体GABRA1水平的影响,进而研究褪黑素的抑痫作用机制。方法随机将健康SD雄性大鼠40只分为A、B、C、D组,每组10只。A组:生理盐水组;B组:MT Glu组;C组:Glu致痫组;D组:Luzidole MT Glu组。观察并记录行为学变化,采用免疫组化法进行Glu、GluR2、GABA和GABRA1免疫组化染色和图像分析。结果行为学观察结果显示,C组和D组大鼠均有不同程度的癫痫发作,B组大鼠癫痫发作不明显,A组无发作;免疫组化结果显示,C组和D组海马内CA1-CA3区和齿状回Glu阳性反应较A组增强(P<0.05),GluR2、GABA和GABRA1均较A组减弱(P<0.05),B组Glu较C组和D组阳性反应有显著性减弱(P<0.05),GluR2、GABA和GABRA1阳性反应均较C组和D组有显著性增强(P<0.05),而B组与A组无明显差异性。结论MT通过增加GABA及其受体GABRA1和GluR2的作用和抑制Glu作用对Glu致痫大鼠癫痫发作发挥抑制作用。     

针灸治疗癫痫后脑损伤的研究

癫痫是一种严重危害人类健康的常见中枢系统病,其反复发作会对脑组织造成损伤,以致产生认知功能障碍.针灸很早即被应用于癫痫的临床治疗,但近年来其改善癫痫后脑损伤实验机制及临床治疗效果的研究才逐渐被加以重视.针灸的优势在于可以通过激发机体自身调节达到治疗目的,从而避免使用抗癫痫药物产生不良反应.针灸改善癫痫后脑损伤的机制以抑制海马区神经元凋亡为主,同时伴有抑制胶质细胞增生、抑制齿状回颗粒层苔藓纤维发芽等.针灸临床效果证实任督二脉取穴配合辨证取穴及头部局部取穴是有效的.本文即是关于针灸治疗癫痫后脑损伤的机制研究及针刺临床疗效的进展综述.     

褪黑素抑制小鼠卵母细胞的体外成熟

目的:探讨褪黑素(MT)对小鼠卵母细胞的体外成熟的影响.方法:通过卵母细胞自发、次黄嘌呤(HX)阻滞和激素诱导成熟三种体外培养模型研究了褪黑素(MT)对小鼠卵母细胞体外成熟的影响.结果:①0.1 g/L、0.02g/L、0.004 g/L及0.0008 g/L浓度的MT均能显著抑制小鼠卵丘卵母细胞复合体(CEOs)自发成熟过程中第一极体(PB1)的释放(P＜0.01);②动力曲线分析表明,MT对自发成熟的CEOs的GVBD和PB1有显著的推后作用,与对照组相比,处理组的GVBD和PB1分别被推后8～10 h和3～4 h;③0.1 g/L和0.02 g/L两有效浓度的MT还能显著抑制促性腺激素(FSH)诱导的HX阻滞的CEOsGVBD的发生(P＜0.05),对PB1的排出虽有一定的抑制作用,但没有统计学意义;④MT和次黄嘌呤(HX)对CEOs的自发成熟有协同抑制作用(P＜0.01),但在裸卵(DO)自发成熟的阻滞中没有协同效应.结论:MT是调节哺乳动物卵母细胞成熟的重要激素之一,其作用机制可能是通过卵丘细胞实现的.     

高频电刺激对大鼠海马脑片癫痫样放电特性影响的研究

本文采用电极阵列检测技术,在大鼠海马脑切片上诱导出稳定的癫痫样放电,分析、研究130 Hz的高频电刺激(high-frequency stimulation,HFS) CA3区时,海马切片在癫痫发作间期放电(inter-ictal discharges,IID)和发作期放电(ictal discharges,ID)的各项参数、癫痫样放电地起始位点、传播方向和传输速率以及各频段的功率谱密度.结果显示:高频电刺激可以有效地降低癫痫发作期的幅值、减少持续时间、增长潜伏时间、抑制癫痫样放电由IID向ID的转变等.提示高频电刺激抑制癫痫的作用机制是通过促进神经元之间的抑制性传输系统,并且抑制海马神经元之间的兴奋性连接,从而达到抑制效果.     

褪黑素对大鼠内毒素性肺损伤抗氧化功能及ICAM-1表达的影响

目的:探讨褪黑素(MT)对大鼠急性肺损伤(ALI)时肺脏的保护作用及其可能机制。方法:将大鼠随机分为4组:对照组;脂多糖(LPS)组;地塞米松(DEX)和MT处理组。各组动物分别于气道内滴注后3、6和12h检测肺组织髓过氧化物酶(MPO)和超氧化物歧化酶(SOD)活性及丙二醛(MDA)含量;免疫组化检测细胞间黏附分子-1(ICAM-1)在肺组织的表达。结果:LPS组SOD活性较对照组明显降低(P<0.01),而MPO活性与MDA含量以及ICAM-1的表达则显著升高(P<0.01);应用MT及DEX均显著缓解上述变化(P<0.05或P<0.01)。结论:MT对ALI时的肺脏起明显的保护作用,其机制可能与MT清除自由基及抑制ICAM-1的表达有关。     

The interaction between microtubules and intermediate filaments in cultured cells treated with taxol and nocodazole

Using double-label immunofluorescence and electron microscopy we studied the interaction between microtubules (MT) and intermediate filaments (IF) in MO cells treated with various combinations of taxol and nocodazole. With taxol, the organized MT of cultured cells are replaced by free MT and MT bundles. This rearrangement of MT is followed by a rearrangement of the IF. As in untreated cells a close association between these two filamentous systems is observed. In cells pretreated with nocodazole followed by addition of taxol, to induce the bundles of free MT, the preexisting IF coils disappear and IF associate with the MT. From these experiments we conclude that an interaction between MT and IF exists independent of the normal organisation of the MT system. The redistribution of IF always follows the redistribution of MT. The data show that MT determine the spatial distribution of IF which most probably involves some kind of physicochemical link.     

Theoretical modeling of aging effects in microtubule dynamics

The microtubule (MT) network, an important part of the cytoskeleton, is constantly remodeled by alternating phases of growth and shrinkage of individual filaments. Plus-end tracking proteins (+TIPs) interact with the MT and in many cases alter its dynamics. Although it is established that some +TIPs modify MT dynamics by increasing rescues, the plus-end tracking mechanism is still under debate. We present a model for MT dynamics in which a rescue factor is dynamically added to the filament during growth. As a consequence, the filament shows aging behavior that should be experimentally accessible and thus allow one to exclude some hypothesized models regarding the inclusion of rescue factors at the MT plus end. This result is not limited to +TIPs and can be extended to any kind of mechanism shifting the parameters of dynamic instability. Additionally, we show that the cell geometry has a strong influence on the quantitative results.     

AmpliBASE MT: a Mycobacterium tuberculosis diversity knowledgebase

AmpliBASE MT is an online databank of high-resolution DNA fingerprints representing fluorescent amplified fragment length polymorphism (FAFLP) profiles or amplitypes developed for the Mycobacterium tuberculosis complex strains from 48 different countries. AmpliBASE MT is based on a relational database management system that is hyperlinked to visualize genotyping results in the form of DNA fingerprint images for individual strains. A flexible search system based on systematic comparisons of fragment sizes in base pairs allows inter-laboratory comparison of FAFLP profiles. Besides this, the database also displays previously published data on IS6110 profiles, spoligotypes, MIRU-VNTRs and large sequence polymorphisms along with the FAFLP records that will give the overall comparisons. Being the first of its kind, AmpliBASE MT is expected to be a very helpful tool in strengthening the concept of 'geographic genomics' and will be very helpful to molecular epidemiologists and those interested in diagnostic development for tuberculosis.     

小鼠金属硫蛋白 Ⅰ cDNA编码序列的克隆及其在昆虫细胞中的表达

将质粒ｐＢＸ－ＭＴ上的小鼠ＭＴ－ⅠｃＤＮＡ片段切下作为模板,通过ＰＣＲ方法删除该片段的非编码序列,将编码序列克隆到质粒ｐＢＳ－ＳＫ中,经ＤＮＡ序列测定后证明其克隆序列正确．再将ＭＴ－ⅠｃＤＮＡ编码序列插入到转移载体ｐＢａｃＰＡＫ８的ＢａｍＨⅠ和ＥｃｏＲⅠ位点之间,通过磷酸钙／ＤＮＡ共转染方法将其导入昆虫细胞Ｓｆ９中,以Ｗｅｓｔｅｒｎｂｌｏｔ和ＤｏｔＥＩＡ方法对表达产物进行了检测,表达量为１ｍｇ／Ｌ     

Nuclear differentiation for mating types in the ciliate Dileptus anser: a hypothesis

We have obtained the first data on inheritance and genetic determination of mating types (MTs) in the lower ciliate Dileptus anser (=D. margaritifer). Observation of MT instability in young, just matured exconjugant clones obtained from some (not all) crosses appears to be the key finding in our study. In a clone of this kind, the states of maturity and immaturity (or adolescence) often alternate and/or one MT changes to another, sometimes repeatedly, during the period of several weeks after the clone's maturation. On occasion, all three MTs found in this species can be expressed consecutively. All cells of the culture are synchronously involved in such changes of their sexual state--no spontaneous selfing (intraclonal conjugation) was ever observed in such cultures. These observations suggest that the mat locus in dilepti is a compound integral one; it is inherited as a whole and can specify expression of any one of possible MTs (much as it occurs in Tetrahymena thermophila). Some other mechanisms, supposedly epigenetic ones among them, control what MT will be expressed in a given exconjugant clone in particular. Steady functioning of these mechanisms provides stable, unambiguous differentiation of the compound mat locus to one and only one MT and subsequent Mendelian behavior of the character over sexual generations. If, for some still unknown reasons the control of such differentiation is disturbed, MT expressed in a given exconjugant clone becomes unstable and its Mendelian behavior can be violated.     

Erratum

The biochemical features of metallothioneins and their functional role in the cell are described. On this basis, the potential role of MTs as a biomarker of exposure in aquatic organisms, such as fishes and molluscs, is evaluated in the light of recent knowledge about MT gene regulation and inducibility. It appears that in fish MTs should be considered as a kind of stress protein which is particularly responsive to heavy metals. In molluscs, in particular in mussels, MTs seem more specifically involved in responses to heavy metals and they should therefore be considered a biomarker of exposure to heavy metal pollution. Common techniques for MT evaluation are listed and a simple spectrophotometric method recently developed is also reported. Finally, the correct approach to the use of MTs as a biomarker of exposure in biomonitoring programmes for an assessment of the physiological status of aquatic organisms is discussed.     

Metallothionein as a tool in biomonitoring programmes

The biochemical features of metallothioneins and their functional role in the cell are described. On this basis, the potential role of MTs as a biomarker of exposure in aquatic organisms, such as fishes and molluscs, is evaluated in the light of recent knowledge about MT gene regulation and inducibility. It appears that in fish MTs should be considered as a kind of stress protein which is particularly responsive to heavy metals. In molluscs, in particular in mussels, MTs seem more specifically involved in responses to heavy metals and they should therefore be considered a biomarker of exposure to heavy metal pollution. Common techniques for MT evaluation are listed and a simple spectrophotometric method recently developed is also reported. Finally, the correct approach to the use of MTs as a biomarker of exposure in biomonitoring programmes for an assessment of the physiological status of aquatic organisms is discussed.     

Polarized growth in fungi--interplay between the cytoskeleton, positional markers and membrane domains

One kind of the most extremely polarized cells in nature are the indefinitely growing hyphae of filamentous fungi. A continuous flow of secretion vesicles from the hyphal cell body to the growing hyphal tip is essential for cell wall and membrane extension. Because microtubules (MT) and actin, together with their corresponding motor proteins, are involved in the process, the arrangement of the cytoskeleton is a crucial step to establish and maintain polarity. In Saccharomyces cerevisiae and Schizosaccharomyces pombe, actin-mediated vesicle transportation is sufficient for polar cell extension, but in S. pombe, MTs are in addition required for the establishment of polarity. The MT cytoskeleton delivers the so-called cell-end marker proteins to the cell pole, which in turn polarize the actin cytoskeleton. Latest results suggest that this scenario may principally be conserved from S. pombe to filamentous fungi. In addition, in filamentous fungi, MTs could provide the tracks for long-distance vesicle movement. In this review, we will compare the interaction of the MT and the actin cytoskeleton and their relation to the cortex between yeasts and filamentous fungi. In addition, we will discuss the role of sterol-rich membrane domains in combination with cell-end marker proteins for polarity establishment.     

HIV-1 SH01分离株在MT4细胞的超微结构特征和形态发生学研究

用外周血单个核细胞混合培养法分离到ＨＩＶ－１ ＳＨ０１株,具有典型的ＨＩＶ颗粒的形态学特征,核心颗粒呈锥形,可见芽生释放的全过程。偶尔可在胞装空泡内见到ＨＩＶ颗粒,同时还有细胞碎片和溶酶体结构,故此类空泡实际为ＨＩＶ吞噬泡。另一少见的现象是溶酶体摄取并消化ＨＩＶ颗粒,在ＨＩＶ－１ ＳＨ０１株感染７天或持续感染的ＭＴ４细胞中均可见到,后者尤为普遍。在ＨＩＶ－１ ＳＨ０１株持续感染的ＭＴ４转化细胞中,     

Structural prediction of the beta-domain of metallothionein-3 by molecular dynamics simulation

The beta-domain of metallothionein-3 (MT3) has been reported to be crucial to the neuron growth inhibitory bioactivity. Little detailed three-dimensional structural information is available to present a reliable basis for elucidation on structure-property-function relationships of this unique protein by experimental techniques. So, molecular dynamics simulation is adopted to study the structure of beta-domain of MT3. In this article, a 3D structural model of beta-domain of MT3 was generated. The molecular simulations provide detailed protein structural information of MT3. As compared with MT2, we found a characteristic conformation formed in the fragment (residue 1-13) at the N-terminus of MT3 owing to the constraint induced by 5TCPCP9, in which Pro7 and Pro9 residues are on the same side of the protein, both facing outward and the two 5-member rings of prolines are arranged almost in parallel, while Thr5 is on the opposite side. Thr5 in MT3 is also found to make the first four residues relatively far from the fragment (residue 23-26) as compared with MT2. The simulated structure of beta-domain of MT3 is looser than that of MT2. The higher energy of MT3 than that of MT2 calculated supports these conclusions. Simulation on the four isomer arising from the cis- or trans-configuration of 6CPCP9 show that the trans-/trans-isomer is energetic favorable. The partially unfolding structure of beta-domain of MT3 is also simulated and the results show the influence of 6CPCP9 sequence on the correct folding of this domain. The correlations between the bioactivity of MT3 and the simulated structure as well as the folding of beta-domain of MT3 are discussed based on our simulation and previous results.