Ruqiang Liang

Neuromodulatory systems exert profound influences on brain function. Understanding how these systems modify the operating mode of target circuits requires spatiotemporally precise measurement of neuromodulator release. We developed dLight1, an intensity-based genetically encoded dopamine indicator, to enable optical recording of dopamine dynamics with high spatiotemporal resolution in behaving mice. We demonstrated the utility of dLight1 by imaging dopamine dynamics simultaneously with pharmacological manipulation, electrophysiological or optogenetic stimulation, and calcium imaging of local neuronal activity. dLight1 enabled chronic tracking of learning-induced changes in millisecond dopamine transients in mouse striatum. Further, we used dLight1 to image spatially distinct, functionally heterogeneous dopamine transients relevant to learning and motor control in mouse cortex. We also validated our sensor design platform for developing norepinephrine, serotonin, melatonin, and opioid neuropeptide indicators.

BACKGROUND: MicroRNAs (miRNAs) are endogenously expressed small RNAs with a length of about 21 nt. MiRNAs silence their target genes at the post-transcriptional level. In plants, miRNAs play various developmental and physiological roles by cleavaging mRNAs predominantly. Drought and high salinity are the most severe environmental abiotic stresses and cause crop losses all over the world. RESULTS: In this study, we identified miR-169g and miR-169n (o) as high salinity-responsive miRNAs in rice. MiR-169n and miR169o were in a miRNA cluster with a distance of 3707 base pairs (bp). The high degree of conservation and close phylogenic distance of pre-miR-169n and pre-miR-169o indicated that they were derived from a very recent tandem duplication evolutionary event. The existence of a cis-acting abscisic acid responsive element (ABRE) in the upstream region of miR-169n (o) suggested that miR-169n (o) may be regulated by ABA. In our previous study, we found that miR-169g was induced by the osmotic stress caused by drought via a dehydration-responsive element (DRE). Thus, our data showed that there were both overlapping and distinct responses of the miR-169 family to drought and salt stresses. We also showed that these miR-169 members selectively cleaved one of the NF-YA genes, Os03g29760, which is a CCAAT-box binding transcription factor and participates in transcriptional regulation of large number genes. Finally, we found one or more ath-miR-169 member that was also induced by high salinity. CONCLUSION: We identified members of the miR-169 family as salt-induced miRNAs and analyzed their evolution, gene organization, expression, transcriptional regulation motif and target gene. Our data also indicated that the salt-induction of some miR-169 members was a general property in plants.

MicroRNAs (miRNAs) play important regulatory roles in animals and plants by targeting mRNAs for cleavage or translational repression. They have diverse expression patterns and might regulate various developmental and physiological processes. Profiling miRNA expression is very helpful for studying biological functions of miRNAs. We report a novel miRNA profiling microarray, in which miRNAs were directly labeled at the 3' terminus with biotin and hybridized with complementary oligo-DNA probes immobilized on glass slides, and subsequently detected by measuring fluorescence of quantum dots labeled with streptavidin bound to miRNAs through streptavidin-biotin interaction. The detection limit of this microarray for miRNA was approximately 0.4 fmol, and the detection dynamic range spanned about 2 orders of magnitude. We made a model microarray to profile 11 miRNAs from leaf and root of rice (Oryza sativa L. ssp. indica) seedlings. The analysis results of the miRNAs had a good reproducibility and were consistent with the northern blot result. To avoid using high-cost detection equipment, colorimetric detection, a method based on nanogold probe coupled with silver enhancement, was also successfully introduced into miRNA profiling microarray detection.