Alternative splicing (AS) has been extensively studied in mammalian systems but much less in plants. Here exon skipping ͉ intron retention ͉ non-sense-mediated decay ͉ spliced alignment ͉ conserved alternative splicing A lternative splicing (AS) is an important posttranscriptional regulatory mechanism that can increase protein diversity and affect mRNA stability (1, 2). Relative to the predominant transcript isoform, different types of AS have been observed, including exon skipping (ExonS), alternative donor (AltD) or acceptor (AltA) site, and intron retention (IntronR) ( Fig. 1; reviewed in ref.3). AS has been extensively studied by EST͞ cDNA-based analysis in mammalian systems, and 35-60% human genes were suggested to be alternatively spliced (4-9). In humans, ExonS is the most common type (58% of the total number of AS events are ExonS events involving a single exon, and 11% are ExonS events in which multiple exons are skipped in tandem) (4). IntronR is the least common type of AS in humans (5%) (4); Ϸ70-88% of the AS events occur in protein coding regions (reviewed in ref. 10), and approximately onethird produce premature termination codons (PTCs) (11). These PTC-containing transcripts are apparent targets for non sensemediated mRNA decay (NMD) (11). Not all of the predicted AS are real and functional, because many possible sources of false positives exist (10). An AS event has been defined as functional ''if it is required during the life cycle of the organism and activated in a regulated manner'' (12). To identify functional AS events, conserved AS events between human and mouse were studied (12-17), with the assumption that conservation indicates function. Twenty-five percent of a set of 980 ExonS events in human were found to be conserved in mouse (12). Another study reported that Ϸ10% of human gene loci with mouse orthologs show conserved AS events (15).The splicing mechanism in plants is generally conserved compared with mammals (18, 19). However, introns in plant are usually short in length and U-rich (18-20), with a much less apparent polypyrimidine tract near the 3Ј splice site than in mammals (21). Our recent genomewide survey on Arabidopsis splicing-related genes revealed variations in SR proteins and hnRNP proteins between plants and mammals, suggesting plantspecific differences in splicing-regulation mechanisms (22). A few AS events were identified experimentally in plants, including genes involved in splicing (23, 24), transcription (25), flowering regulation (26), disease resistance (27), enzyme activities (28, 29), and many other physiological processes and functions (19). A database (PASDB) collecting known alternatively spliced genes in plants is available at http:͞͞pasdb.genomics.org.cn (30).

Predicting the formation of ice in the atmosphere presents one of the great challenges in 14 physical sciences with important implications for the chemistry and composition of the Earth's atmos-15 phere, the hydrological cycle, and climate. Among atmospheric ice formation processes, heterogeneous 16 ice nucleation proceeds on aerosol particles ranging from a few nanometers to micrometers in size, 17 commonly referred to as ice nucleating particles (INPs). Research over the last two decades has demon-18 strated that organic matter (OM) is ubiquitous in the atmosphere, present as organic aerosol (OA) parti-19 cles or as coatings on other particle types. The physicochemical properties of OM make predicting how 20 OM can contribute to the INP population challenging. This review focuses on the role of OM in INPs, 21

[1] Chemical imaging analysis of internally mixed sea salt/organic particles collected onboard the Department of Energy (DOE) G-1 aircraft during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) was performed using electron microscopy and X-ray spectro-microscopy. Substantial chloride depletion in aged sea salt particles was observed, which could not be explained by the known atmospheric reactivity of sea salt with inorganic nitric and sulfuric acids. We present field evidence that chloride components in sea salt particles may effectively react with organic acids releasing HCl gas to the atmosphere, leaving behind particles depleted in chloride and enriched in the corresponding organic salts. While formation of the organic salts products is not thermodynamically favored for bulk aqueous chemistry, these reactions in aerosol are driven by high volatility and evaporation of the HCl product from drying particles. These field observations were corroborated in a set of laboratory experiments where NaCl particles mixed with organic acids were found to be depleted in chloride. Combined together, the results indicate substantial chemical reactivity of sea salt particles with secondary organics that has been largely overlooked in the atmospheric aerosol chemistry. Atmospheric aging, and in particular hydration-dehydration cycles of mixed sea salt/organic particles, may result in formation of organic salts that will modify the acidity, hygroscopic, and optical properties of aged particles.

[1] Secondary organic aerosol (SOA) generated from the oxidation of organic gases are ubiquitous in the atmosphere, but their interaction with water vapor and their ice cloud formation potential at low temperatures remains highly uncertain. We report on onset conditions of water uptake and ice nucleation by amorphous SOA particles generated from the oxidation of naphthalene with OH radicals. Water uptake above 230 K was governed by the oxidation level of the SOA particles expressed as oxygen-to-carbon (O/C) ratio, followed by moisture-induced phase transitions and immersion freezing. For temperatures from 200 to 230 K, SOA particles nucleated ice via deposition mode from supersaturated water vapor independent of O/C ratio at relative humidity with respect to ice (RH ice ) $10-15% below homogeneous ice nucleation limits. The glass transition temperature (T g ) for the amorphous SOA particles was derived as a function of two parameters: (1) relative humidity (RH) with respect to water and (2) oxidation level of the SOA. The data show that particle phase and viscosity govern the particles' response to temperature and RH and provide a straightforward interpretation for the observed different heterogeneous ice nucleation pathways and water uptake by the laboratory-generated SOA and field-collected particles. Since SOA particles undergo glass transitions, these observations suggest that atmospheric SOA are potentially important for ice cloud formation and climate.

Background-Essential hypertension has been recognized as a disease resulting from a combination of environmental and genetic factors. Recent studies demonstrated that microRNAs (miRNAs) are involved in cardiac hypertrophy and heart failure. However, little is known about the roles of miRNAs in essential hypertension. Methods and Results-Using microarray-based miRNA expression profiling, we compared the miRNA expressions in plasma samples from 13 hypertensive patients and 5 healthy control subjects. Twenty-seven miRNAs were found to be differentially expressed. The expressions of selected miRNAs (miR-296 -5p, let-7e, and a human cytomegalovirus [HCMV]-encoded miRNA, hcmv-miR-UL112) were validated independently in plasma samples from 24 hypertensive patients and 22 control subjects. The absolute expression levels of hcmv-miR-UL112, miR-296 -5p, and let-7e were further determined in 127 patients and 67 control subjects (fold changes are 2.5, 0.5, and 1.7 respectively; all PϽ0.0001). Additionally, we demonstrated that interferon regulatory factor 1 is a direct target of hcmv-miR-UL112.Increased HCMV seropositivity and quantitative titers were found in the hypertension group compared with the control group (52.7% versus 30.9%, Pϭ0.0005; 1870 versus 54 copies per 1 mL plasma, PϽ0.0001). Seropositivity, log-transformed copies of HCMV, and hcmv-miR-UL112 were independently associated with an increased risk of hypertension (odds ratio, 2.48; 95% confidence interval, 1.48 to 4.15; Pϭ0.0005; odds ratio, 1.97; 95% confidence interval, 1.58 to 2.46; PϽ0.0001; and odds ratio, 2.55; 95% confidence interval, 1.98 to 3.27; PϽ0.0001, respectively). Conclusions-We report for the first time a circulating miRNA profile for hypertensive patients and demonstrate a novel link between HCMV infection and essential hypertension. These findings may reveal important insights into the pathogenesis of essential hypertension. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00420784. Key Words: cytomegalovirus Ⅲ hypertension Ⅲ interferon regulatory factor-1 Ⅲ microRNAs E ssential hypertension is a predisposing risk factor for stroke, myocardial infarction, congestive heart failure, and arterial aneurysm; it is also the leading cause of chronic renal failure. 1 Approximately 90% to 95% of hypertension, affecting Ͼ1 billion adults worldwide, is the essential hypertension subtype. 2 Discernment between essential and secondary hypertension is critical because the former has no precise cause and the latter has a clear cause usually remediable by a Clinical Perspective on p 184 microRNAs (miRNAs) are short, endogenous, noncoding RNAs that regulate gene expression at the posttranscriptional level by binding to the 3Ј untranslated regions (UTRs) of their target mRNAs. 7 Although dysregulation of miRNA expression is a feature of malignancies, 8 -10 research into miRNAs in biological processes reveals their regulation of immune cell development, 11 involvement in inflammatory response, 12 and critical participation...

[1] Heterogeneous ice nucleation plays important roles in cirrus and mixed-phase cloud formation, but the efficiency of organic particles to act as ice nuclei (IN) is still not well understood. Furthermore, the effect of particle oxidation by O 3 on corresponding IN efficiencies has not yet been sufficiently assessed. We present heterogeneous ice nucleation on kaolinite, Suwannee River standard fulvic acid (SRFA), and leonardite standard humic acid particles as a function of particle temperature (T p ), relative humidity with respect to ice (RH ice ), nucleation mode, and O 3 exposure. Ice nucleation and water uptake were studied for T p >203 K and RH ice up to water saturation using a novel ice nucleation apparatus. This study shows that SRFA, leonardite, and corresponding O 3 -exposed particles can nucleate ice via different modes at relevant atmospheric conditions. These particles nucleated ice via deposition mode at T p ≤ 231 K, and for higher T p water was taken up or ice was nucleated via deposition or immersion mode. Oxidation of leonardite and SRFA particles by O 3 led to a decrease in deposition nucleation efficiency and to water uptake at lower temperatures for the former and to an increase in the lowest temperature at which deposition nucleation was observed for the latter. Activated IN fractions and heterogeneous ice nucleation rate coefficients (J het ) were derived, and corresponding contact angles ( ) were calculated. A parameterization of as a function of RH ice is presented which allows derivation of J het for various deposition IN and corresponding ice crystal production rates for application in cloud-resolving models.

Alternative splicing enhances transcriptome diversity in all eukaryotes and plays a role in plant tissue identity and stress adaptation. To catalog new maize (Zea mays) transcripts and identify genomic loci that regulate alternative splicing, we analyzed over 90 RNA-seq libraries from maize inbred lines B73 and Mo17, as well as Syn10 doubled haploid lines (progenies from B73 3 Mo17). Transcript discovery was augmented with publicly available data from 14 maize tissues, expanding the maize transcriptome by more than 30,000 and increasing the percentage of intron-containing genes that undergo alternative splicing to 40%. These newly identified transcripts greatly increase the diversity of the maize proteome, sometimes coding for entirely different proteins compared with their most similar annotated isoform. In addition to increasing proteome diversity, many genes encoding novel transcripts gained an additional layer of regulation by microRNAs, often in a tissue-specific manner. We also demonstrate that the majority of genotype-specific alternative splicing can be genetically mapped, with cis-acting quantitative trait loci (QTLs) predominating. A large number of trans-acting QTLs were also apparent, with nearly half located in regions not shown to contain genes associated with splicing. Taken together, these results highlight the currently underappreciated role that alternative splicing plays in tissue identity and genotypic variation in maize.

Despite the great efforts that have been made toward obtaining Janus architectures, synthesizing sub-10 nanometer Janus nanoparticles (NPs) modified with different types of polymers remains a challenging task. In this Communication, "solid-state grafting-to" and "grafting-from" methods were combined to obtain Janus gold NPs (AuNPs) modified with two types of polymer chains on the opposite sides of the NP. We used functionalized polymer single crystals as the solid substrates to immobilize AuNPs. We then used atom transfer radical polymerization to grow polymer chains on the "free" side of the AuNPs. Amphiphilic polyethylene oxide (PEO)-Au-poly(methyl methacrylate), PEO-Au-poly(tert-butyl acrylate) and hydrophilic PEO-Au-poly(acrylic acid) were synthesized. The Janus nature was demonstrated using a platinum-nanoparticle-decoration method. Using polymer single crystals as the reaction substrates is advantageous because they afford higher throughput compared with self-assembled monolayers. Dissolution of the single crystal also leads to NPs with defined polymer patches. We anticipate that our approach could serve as a generic method for synthesizing polymer-functionalized, sub-10 nm Janus NPs. This unique system holds promises for achieving controlled assembly and tunable optic and electronic properties of NPs.