The chemokine interleukin-8 acutely reduces Ca(2+) currents in identified cholinergic septal neurons expressing CXCR1 and CXCR2 receptor mRNAs

The chemokine IL-8 is known to be synthesized by glial cells in the brain. It has traditionally been shown to have an important role in neuroinflammation but recent evidence indicates that it may also be involved in rapid signaling in neurons. We investigated how IL-8 participates in rapid neuronal signaling by using a combination of whole-cell recording and single-cell RT-PCR on dissociated rat septal neurons. We show that IL-8 can acutely reduce Ca(2+) currents in septal neurons, an effect that was concentration-dependent, involved the closure of L- and N-type Ca(2+) channels, and the activation of G(ialpha1) and/or G(ialpha2) subtype(s) of G-proteins. Analysis of the mRNAs from the recorded neurons revealed that the latter were all cholinergic in nature. Moreover, we found that all cholinergic neurons that responded to IL-8, expressed mRNAs for either one or both IL-8 receptors CXCR1 and CXCR2. This is the first report of a chemokine that modulates ion channels in neurons via G-proteins, and the first demonstration that mRNAs for CXCR1 are expressed in the brain. Our results suggest that IL-8 release by glial cells in vivo may activate CXCR1 and CXCR2 receptors on cholinergic septal neurons and acutely modulate their excitability by closing calcium channels.     

Expression and signaling of group I metabotropic glutamate receptors in astrocytes and microglia

Stimulation of astrocytes with the excitatory neurotransmitter glutamate leads to the formation of inositol 1,4,5-trisphosphate and the subsequent increase of intracellular calcium content. Astrocytes express both ionotropic receptors and metabotropic glutamate (mGlu) receptors, of which mGlu5 receptors are probably involved in glutamate-induced calcium signaling. The mGlu5 receptor occurs as two splice variants, mGlu5a and mGlu5b, but it was hitherto unknown which splice variant is responsible for the glutamate-induced effects in astrocytes. We report here that both mRNAs encoding mGlu5 receptor splice variants are expressed by cultured astrocytes. The expression of mGlu5a receptor mRNA is much stronger than that of mGlu5b receptor mRNA in these cells. In situ hybridization experiments reveal neuronal expression of mGlu5b receptor mRNA in adult rat forebrain but a strong neuronal expression of mGlu5a mRNA only in olfactory bulb. Signals for mGlu5a receptor mRNA in the rest of the brain were diffuse and weak but consistently above background. Activation of mGlu5 receptors in astrocytes yields increases in inositol phosphate production and transient calcium responses. It is surprising that the rank order of agonist potency [quisqualate > (2S,1 'S,2'S)-2-(carboxycyclopropyl)glycine = trans-(1S,3R)-1-amino-1,3-cyclopentanedicarboxylic acid (1S,3R-ACPD) > glutamate] differs from that reported for recombinantly expressed mGlu5a receptors. The expression of mGlu5a receptor mRNA and the occurrence of 1S,3R-ACPD-induced calcium signaling were found also in cultured microglia, indicating for the first time expression of mGlu5a receptors in these macrophage-like cells.     

Filamentous Alphaproteobacteria associated with bulking in industrial wastewater treatment plants

The phylogeny and distribution of filamentous Alphaproteobacteria, morphologically similar to “Nostocoida limicola” and Eikelboom Type 021N that cause the solids separation problem of bulking in industrial activated sludge plants is described here. A combination of culture-dependent and culture-independent molecular methods has characterized 5 novel species. 16S rRNA targeted oligonucleotide probes were designed for their in situ identification by fluorescence in situ hybridisation (FISH) and used to monitor their presence in 86 WWTPs treating different industrial effluents in four European countries. The involvement of these bacteria in bulking in these plants was confirmed. Filaments hybridising with the ALF-968 probe for the Alphaproteobacteria were present in 65% of the WWTPs examined. They were dominant and therefore probably responsible for bulking in 25.5% of them. The heterogeneous filamentous alphaproteobacterial populations in these communities could be completely identified after application of the oligonucleotide probes used in this study in 91% of the plants containing them. The only filamentous Alphaproteobacteria retrieved in pure culture was isolated from three different industrial WWTPs plants. None of these isolates could grow anaerobically on glucose or denitrify, but all grew aerobically and heterotrophically on a range of carbon sources. Although morphologically similar to the Eikelboom Type 021N morphotype, they were not involved in sulphur metabolism. These bacteria accumulated lipidic storage granules that were associated with their presence under the unbalanced growth conditions existing in these plants.     

Isolating high-quality RNA from mangroves without liquid nitrogen

Mangroves form unique communities in tropical coastal regions and tidal lowlands. Isolating RNA from mangrove leaves is difficult because of high amounts of secondary metabolites and polysaccharides. Conventional extraction methods produce poor-quality mangrove RNA. We present a simple, fast, and convenient protocol for isolating RNA from 5 mangrove species:Aegiceras corniculatum, Bruguiera gymnorrhiza, Ceriops tagal, Kandelia candel, andSonneratia apetala. Isolating RNA from other mangrove species is also possible. Obtained RNA was of high quality and used in an RT-PCR reaction that amplified 0.6 kb of theA. corniculatum CPI-1 gene.     

不同频率慢性电刺激膈神经对兔膈肌骨骼肌型二氢吡啶受体α1亚单位、ryanodine受体mRNA和蛋白表达的影响

测定不同频率慢性电刺激(chronic electrical stimulation,CES)膈神经5周后对兔膈肌钙释放单位中骨骼肌型二氢吡啶受体(DHPR)α1亚单位和ryanodine受体(RyRs)的mRNA和蛋白表达水平的影响,探讨CES后兔膈肌钙释放单位结构组成的变化和可能的临床应用价值.封闭群日本大耳白兔30只,随机分为正常对照组、10、20、50和100Hz,每组6只;以10和20 Hz为慢性低频电刺激组,50和100Hz为慢性高频电刺激组.CES参数为波宽0.2 ms 3～6个波/次,45次/min,电压10～20 V.刺激时间2×2 h/日,每周刺激6 d,连续刺激5周.分别采用RT-PCR和免疫组织化学法测定兔膈肌骨骼肌型DHPRα1-亚单位和RyR1、RyR2和RyR3的mRNA和蛋白表达.结果显示与对照组比较,慢性低频电刺激10和20 Hz组骨骼肌型DHPRα1、RyR的mRNA和蛋白表达明显降低(P＜0.01),有低度的RyR,mRNA的表达出现;慢性高频电刺激50和100Hz组骨骼肌型DHPRα1、RyR1的mRNA和蛋白表达明显升高(P＜0.01),未检测到RyR2mRNA的阳性表达.本实验提示慢性低频电刺激膈神经5周后,膈肌质膜上DHPR与RyRs之间的信号转导方式已从变构耦联为主转变为以Ca2+诱导Ca2+释放耦联为主.