Constantly expressed genes are used as internal controls in relative quantification studies. Suitable internal controls for such studies have not yet been defined for Pseudomonas aeruginosa. In this study, the genes ampC, fabD, proC, pbp-2, rpoD and rpoS of P. aeruginosa were compared in terms of expression stability by real-time quantitative RT-PCR. A total of 23 strains with diverse resistance phenotypes were studied. Stability of expression among the housekeeping genes was assessed on the basis of correlation coefficients, with the best-correlated pair accepted as being the most stable one. Eventually, proC and rpoD formed the most stable pair (r ¼ 0·958; P , 0·001). Next, in four ciprofloxacin-selected nfxC-like mutants, levels of oprD, oprM and oprN mRNA were compared with those of their wild-type counterparts. The comparison was made after correcting the raw values by the geometric mean of the internal control genes proC and rpoD. The level of oprN mRNA was significantly up-regulated, while the oprD gene was down-regulated (although this difference was statistically insignificant), in the mutants. This expression pattern was consistent with that of the expected expression profile of nfxC-type mutants; this experiment therefore lends further support to the use of proC and rpoD genes simultaneously as internal controls for such studies.

Agomelatine, a novel antidepressant with established clinical efficacy, acts as an agonist of melatonergic MT1 and MT2 receptors and as an antagonist of 5-HT2C receptors. The present study was undertaken to investigate whether chronic treatment with agomelatine would block unpredictable chronic mild stress (UCMS)-induced cognitive deterioration in mice in passive avoidance (PA), modified elevated plus maze (mEPM), novel object recognition (NOR), and Morris water maze (MWM) tests. Moreover, the effects of stress and agomelatine on brain-derived neurotrophic factor (BDNF) and cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) messenger ribonucleic acid (mRNA) levels in the hippocampus was also determined using quantitative real-time polymerase chain reaction (RT-PCR). Male inbred BALB/c mice were treated with agomelatine (10 mg/kg, i.p.), melatonin (10 mg/kg), or vehicle daily for five weeks. The results of this study revealed that UCMS-exposed animals exhibited memory deterioration in the PA, mEPM, NOR, and MWM tests. The chronic administration of melatonin had a positive effect in the PA and +mEPM tests, whereas agomelatine had a partial effect. Both agomelatine and melatonin blocked stress-induced impairment in visual memory in the NOR test and reversed spatial learning and memory impairment in the stressed group in the MWM test. Quantitative RT-PCR revealed that CREB and BDNF gene expression levels were downregulated in UCMS-exposed mice, and these alterations were reversed by chronic agomelatine or melatonin treatment. Thus, agomelatine plays an important role in blocking stress-induced hippocampal memory deterioration and activates molecular mechanisms of memory storage in response to a learning experience.

Summary. The alterations in gene expression associated with 1,25(OH) 2 D 3 -induced differentiation of HL-60 cells were studied in order to identify potential targets for further investigation of the genetic basis of acute myeloid leukaemia. Atlas human haematology filters, including 406 genes (Clontech), were used to study gene expression in response to 1,25(OH) 2 D 3 (concentration, 5 · 10 )8 mol/l) for 24 and 72 h. Compared with untreated cells, expression differences were found in 43 genes. Downregulated genes at both time-points were: IL2RA, CMYC, NPM, DEK, AF4, FLI1, HTLF, MNDA, BCR, IKAROS, BPI and NFAT4. Upregulated genes at both time-points were IL1B, CD14 and MCL1. CD55, CD58, IRF2, CREB1, ATF4, RAC1, TIAR, KIAA0053, BAT2, BTK, RCK, EV12B and EDN were downregulated at 24 h, while SPI1, MKK3, BTG1 and IL8were upregulated. At 72 h the upregulated genes were IL1RA, IL2RG, CXCR4, SCYA1, SCYA3, SCYA4, SCYA5, SCYA22, ANX2, CD83 and UPAR. cDNA array results were confirmed on randomly selected genes using quantitative real-time polymerase chain reaction for three upregulated (CXCR4, IL1B and CD14) and three downregulated (DEK, AF4 and FLI1) genes. Gene expression analysis after differentiation induction may provide a tool to study the roles of DEK, AF4 and FLI1 in cell proliferation and differentiation. To demonstrate the genes that initiate differentiation, sequential gene expression analysis has to be performed during the first 24 h of the differentiation process.