Genome-wide analysis of small RNA and novel microRNA discovery during fiber and seed initial development in Gossypium hirsutum. L.

Cotton is the source of the most important, renewable natural textile fiber and oil in the world. MicroRNAs (miRNAs) are endogenous, non-coding, approximately 18-24 nucleotides long RNAs and function in the negative regulation of their target genes. Two mostly overlapping libraries of small RNA molecules were constructed and sequenced, and served as repetition sets of data to identify miRNAs involved in fiber initiation and seed development. The D genome sequence of Gossypium raimondii was used in conjunction with EST sequences to predict miRNA precursors. Overall, 93 new miRNA precursors were identified, of which 28 belonged to 10 known families and the other 65 were considered to be novel miRNAs. Seven hundred EST sequences were proposed to be candidate target genes which involved in the regulation of a diverse group of genes with diverse functions and transcription factors. Some of the novel miRNAs and candidate target genes were validated by the Northern blot and rapid amplification of 5' cDNA ends (5' RACE)

Catalytic Reductive <i>ortho</i>-C–H Silylation of Phenols with Traceless, Versatile Acetal Directing Groups and Synthetic Applications of Dioxasilines

A new, highly selective, bond functionalization strategy, achieved via relay of two transition metal catalysts and the use of traceless acetal directing groups, has been employed to provide facile formation of C–Si bonds and concomitant functionalization of a silicon group in a single vessel. Specifically, this approach involves the relay of Ir-catalyzed hydrosilylation of inexpensive and readily available phenyl acetates, exploiting disubstituted silyl synthons to afford silyl acetals and Rh-catalyzed <i>ortho</i>-C–H silylation to provide dioxasilines. A subsequent nucleophilic addition to silicon removes the acetal directing groups and directly provides unmasked phenol products and, thus, useful functional groups at silicon achieved in a single vessel. This traceless acetal directing group strategy for catalytic <i>ortho-</i>C–H silylation of phenols was also successfully applied to preparation of multisubstituted arenes. Remarkably, a new formal α-chloroacetyl directing group has been developed that allows catalytic reductive C–H silylation of sterically hindered phenols. In particular, this new method permits access to highly versatile and nicely differentiated 1,2,3-trisubstituted arenes that are difficult to access by other catalytic routes. In addition, the resulting dioxasilines can serve as chromatographically stable halosilane equivalents, which allow not only removal of acetal directing groups but also introduce useful functional groups leading to silicon-bridged biaryls. We demonstrated that this catalytic C–H bond silylation strategy has powerful synthetic potential by creating direct applications of dioxasilines to other important transformations, examples of which include aryne chemistry, Au-catalyzed direct arylation, sequential orthogonal cross-couplings, and late-stage silylation of phenolic bioactive molecules and BINOL scaffolds

Modular Approach to Reductive C_sp2–H and C_sp3–H Silylation of Carboxylic Acid Derivatives through Single-Pot, Sequential Transition Metal Catalysis

We report a modular approach to catalytic reductive C_sp2–H and C_sp3–H silylation of carboxylic acid derivatives encompassing esters, ketones, and aldehydes. Choice of either an Ir­(I)/Rh­(I) or Rh­(I)/Rh­(I) sequence leads to either exhaustive reductive ester or reductive ketone/aldehyde silylation, respectively. Notably, a catalyst-controlled direct formation of doubly reduced silyl ethers is presented, specifically via Ir-catalyzed exhaustive hydrosilylation. The resulting silyl ethers undergo C_sp2–H and benzylic C_sp3–H silylation in a single vessel

Mechanistic Insights into Grubbs-Type Ruthenium-Complex-Catalyzed Intramolecular Alkene Hydrosilylation: Direct σ‑Bond Metathesis in the Initial Stage of Hydrosilylation

Grubbs-type ruthenium-complex-mediated intramolecular alkene hydrosilylation of alkenylsilyl ethers has been developed to provide cyclic silyl ethers with high regioselectivity. This non-metathetical use of such ruthenium complexes for alkene hydrosilylation via preferential Si–H bond activation over alkene activation is notable, where the competing alkene metathesis dimerization was not detected. In addition to the synthesis of organosilicon heterocycles from readily available olefins, this study provides fundamental mechanistic insights into the non-metathetical function of Grubbs-type ruthenium catalysts. In the initial stage of hydrosilylation within a ruthenium coordination sphere, evidence for activation of a ruthenium complex by direct σ-bond metathesis between Si–H and Ru–Cl via a four-centered transition state is presented. This study counters the traditionally accepted Chauvin-type mechanism, specifically the addition of R₃Si–H across the π-bond of a Ru-benzylidene

Statistics of small RNA sequence reads.

<p>Statistics of small RNA sequence reads.</p

Sequence read counts of small RNAs obtained by sequencing the two libraries.

<p>Each point represents a unique small RNA in this log-log scatter plot. The points in red are small RNAs found in both libraries.</p

5′ RACE verification of predicted miRNA target genes.

<p>The cleavage sites of two selected targets in two miRNA as identified by 5′ RACE analysis. For each miRNA, the miRNA sequence is shown on the top and the target sequence on the bottom. Arrows indicate the cleavage site of the mRNA, and the frequency of clones was shown under the arrow.</p

Sequence length distribution of cotton small RNA libraries of TM-1L-A and TM-1L-B.

<p>24-nucleotides reads were of significant greater proportion (∼70%) than others.</p

Conserved miRNA families expression in cotton.

<p>FoRPM, reads per million. Fold, fold change of TM-1L-A/TM-1L-B.</p

An investigation on the respiratory mechanics of mechanically ventilated patients during spontaneous breathing trials with enhanced low‐level pressure support ventilation

Abstract Introduction Low‐level pressure support ventilation (PSV) is most commonly adopted in spontaneous breathing trials (SBTs), and some have proposed setting the positive end‐expiratory pressure (PEEP) to 0 cmH2O in order to shorten the observation time of SBTs. This study aims to investigate the effects of two PSV protocols on the patients' respiratory mechanics. Material and method A prospective randomized self‐controlled crossover design was adopted in this study, which involved enrolling 30 difficult‐to‐wean patients who were admitted to the intensive care unit of the First Affiliated Hospital of Guangzhou Medical University between July 2019 and September 2021. Patients were subjected to the S group (pressure support: 8 cmH2O, PEEP: 5 cmH2O) and S1 group (PS: 8 cmH2O, PEEP: 0 cmH2O) for 30 min in a random order, and respiratory mechanics indices were dynamically monitored via a four‐lumen multi‐functional catheter with an integrated gastric tube. Among the 30 enrolled patients, 27 were successfully weaned. Result The S group showed higher airway pressure (Paw), intragastric pressure (Pga) and airway pressure–time product (PTP) than the S1 group. The S group also showed a shorter inspiratory trigger delay, (93.80 ± 47.85) versus (137.33 ± 85.66) ms (P = 0.004); and fewer abnormal triggers, (0.97 ± 2.65) versus (2.67 ± 4.48) (P = 0.042) compared with the S1 group. Stratification based on the causes of mechanical ventilation revealed that under the S1 protocol, patients with chronic obstructive pulmonary disease (COPD) had a longer inspiratory trigger delay compared to both post‐thoracic surgery (PTS) patients and patients with acute respiratory distress syndrome. Despite providing greater respiratory support, S group led to significant reductions in inspiratory trigger delay and less abnormal triggers compared to S1 group, especially among patients with chronic obstructive pulmonary disease. Conclusion These findings suggest that the zero PEEP group was more likely to induce a higher number of patient–ventilator asynchronies in difficult‐to‐wean patients