Microarray-based analysis of stress-regulated microRNAs in Arabidopsis thaliana.

High-salinity, drought, and low temperature are three common environmental stress factors that seriously influence plant growth and development worldwide. Recently, microRNAs (miRNAs) have emerged as a class of gene expression regulators that have also been linked to stress responses. However, the relationship between miRNA expression and stress responses is just beginning to be explored. Here, we identified 14 stress-inducible miRNAs using microarray data in which the effects of three abiotic stresses were surveyed in Arabidopsis thaliana. Among them, 10 high-salinity-, four drought-, and 10 cold-regulated miRNAs were detected, respectively. miR168, miR171, and miR396 responded to all of the stresses. Expression profiling by RT-PCR analysis showed great cross-talk among the high-salinity, drought, and cold stress signaling pathways. The existence of stress-related elements in miRNA promoter regions provided further evidence supporting our results. These findings extend the current view about miRNA as ubiquitous regulators under stress conditions.

An optimized RNA amplification method for prokaryotic expression profiling analysis.

DNA microarray technology has been extensively used for gene expression analysis of both eukaryotic and prokaryotic organisms. For eukaryotic gene expression profiling, the poly(A)-based reverse transcription of messenger RNA (mRNA) followed by T7 RNA polymerase-based in vitro transcription is generally required to produce enough RNA targets for hybridization with the microarray chips. However, the same method cannot be directly applied to prokaryotic mRNAs due to the lack of poly(A) sequences at the 3' ends. Conventional methods usually require large amounts of starting RNAs and lead to high background noise. Recently developed amplification methods enable smaller amounts of prokaryotic RNA to be used from samples with species-specific primers, oligo(dT) primers, or random primers. In this study, three target preparation methods, including the direct labeling, polyadenylation-involved oligo-dT priming, and random priming amplification (respectively referred to as DL, PAOD, and RPA hereafter) were evaluated through expression profiling of a heat shock model of Escherichia coli. The PAOD method was found to be more sensitive and more specific in differential gene expression measurements than either DL and RPA, even when the E. coli RNA was only a small proportion of the simulated eukaryotic host RNA. The results suggest that PAOD is the preferred target preparation method for prokaryotic transcriptome.

[Changes of amino acids neurotransmitters in striatum of hemi-parkinsonian rhesus monkey after high frequency stimulation of subthalamic nucleus].

OBJECTIVE: To investigate the influence of high frequency stimulation of the subthalamic nucleus on the levels of amino acids neurotransmitters in striatum of hemi-parkinsonian monkeys. METHODS: Two rhesus monkeys were successfully prepared for the subsequent microdialysis sessions. Collecting the dialysate before turning on the pulse generator, and collecting at 1 week, 1, 8 and 12 months after high frequency stimulation of the subthalamic nucleus. The level of Glu, GABA and Tau were determined by high performance liquid chromatography and fluorometric detection (HPLC-FD). RESULTS: After high frequency stimulation (HFS), PD symptoms of monkeys significantly improved. The levels of Glu in putamen and caudate nucleus of electrodes side at 1 week, 1, 8 and 12 months were increased significantly. The levels of GABA in putamen and caudate nucleus of electrodes side at 1 week, 1 month increased significantly compared with before turning on the pulse generator while decreased at 8, 12 months. The level of Tau in putamen and caudate nucleus increased significantly. CONCLUSION: Long-term STN HFS can increase the level of glutamate and taurine, while decrease the level of GABA in putamen and caudate nucleus of electrodes side. It improves symptoms of hemi-parkinsonian rhesus monkey significantly.

NTZIP antisense plants show reduced chlorophyll levels.

We have isolated and characterized a new photosynthetic tissue-specific gene NTZIP (Nicotiana tabacum leucine zipper) from tobacco (N. tabacum). Its deduced amino acid sequence has two highly conserved regions, leucine zipper and [EX(n)DEXRH](2) motifs, which are related to the gene's biochemical functions. NTZIP was expressed in leaves and stems, but was not detected in roots or flowers, suggesting that its physiological functions might be associated with photosynthesis. Northern blot analysis showed that NTZIP mRNA accumulation was induced by light signals, increased greatly under low temperatures and was repressed by strong light illumination. Furthermore, a number of homologs of NTZIP were isolated from cucumber (Cucumis sativus), rape (Brassica napus), clover (Trifolium repens), willow (Salix babylonica), rosebush (Rusa dovurica), wheat (Triticum aestivum) and spinach (Spinacia oleracea), proving the ubiquitous existence of the NTZIP-like genes in higher plants. Transgenic tobaccos constitutively expressing antisense RNA to NTZIP displayed chlorosis and a lack of ability to turn green even under normal growth conditions. The chlorophyll deficiency was further confirmed by chlorophyll content determination and gas exchange analysis. Based on these observations, we propose that NTZIP may be involved in chlorophyll biosynthesis, and might define a novel family of evolutionarily conserved proteins with its homologs in other plant species.

Long term high frequency stimulation of STN increases dopamine in the corpus striatum of hemiparkinsonian rhesus monkey.

Long term subthalamic nucleus (STN) high frequency stimulation (HFS) can improve most symptoms of Parkinson's disease (PD) patients and decrease the dosage of antiparkinsonian drug such as Madopar. The mechanism of STN HFS for PD still remains elusive. We hypothesize that the level of dopamine (DA) and its metabolites in the corpus striatum is increased after long term STN HFS. The aim of this study was to examine the DA and its metabolites in the extracellular space of corpus striatum in hemiparkinsonian monkeys during long term STN HFS. Four rhesus monkeys were induced to hemiparkinsonian models by injecting 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) through right internal carotid artery. Then two of them were underwent long term right STN HFS for the subsequent microdialysis sessions. Four microdialysis probe cannulas were implanted into bilateral putamen and caudate nucleus respectively. The microdialysis probe was put into the microdialysis probe cannula of bilateral putamen and caudate nucleus. Dialysates of extracellular space in corpus striatum were collected prior to STN HFS, and subsequently 8 h, 1 week, 1 month, 2 months, 8 months and 10 months after STN HFS. The level of DA and its metabolites were determined by high performance liquid chromatography and subthalamic nucleus electrochemical detection (HPLC-ECD). HFS significantly improved PD symptoms of the monkeys. Rotation evoked by apomorphine (APO) disappeared immediately after HFS pulse generator was turned on. The levels of DA and its metabolites in putamen and caudate nucleus of electrode side increased significantly at different time points after stimulation. Long term STN HFS significantly improved symptoms of hemiparkinsonian rhesus monkey, which might be due to the increase of dopamine and/or its metabolites in corpus striatum.