Crystal Chiral Symmetry Breaking: A Self-Seed Inducing Effect Controlled by Kinetics

We have studied the mechanism of crystal chiral symmetry breaking through the competition between two enantiomorphs using the inducing nucleation of two seeds, one of each chirality, under an ultrasonic field. A seed, introduced into its supersaturated solution earlier only 1–2 min than another seed with opposite handedness, can dominate the chirality of final products, and when two seeds with opposite handedness were simultaneously introduced into the solution, the ee's of the final products were closely related to the proportion of the clusters of two enantiomorphs. Our result suggests that the realization of the crystal chiral symmetry breaking under an ultrasonic field is via a self-seed inducing effect controlled by kinetics, in particular, depending on the difference between the rate of secondary nucleation induced by a primary nucleus and the rate of primary nucleation, while a primary nucleus can make the solute around it pile up in one way of the same handedness as it and rapidly coalesce on the clusters of the same handedness as it, leading to a large secondary nucleation rate

The association between inflammatory biomarkers and low back disorder: a systematic review and meta-analysis

Low back disorder (LBD) is a major cause of disability worldwide. Inflammation results in proliferation of cytokines or consequent degradation products (collectively known as inflammatory biomarkers) that activate pain pathways which can result in non-specific LBD. This systematic review and meta-analysis aim to evaluate the relationship between inflammatory biomarkers and clinical outcomes in patients with LBD. The PRISMA guideline was followed for the systematic reivew. Three online databases were searched. Four RCTs and sixteen observational studies with 1142 LBD patients were analysed. The primary outcomes were back and leg pain scores, back-specific disability scores and expression of inflammatory biomarkers. Standardized mean difference (SMD) and their 95% confidence intervals (CI) were evaluated. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to summarize the strength of evidence. Four RCTs and sixteen observational studies were included in the analysis of 1142 patients with LBD. There was a statistically significant reduction in back pain score and IL-1 beta and increase in the expression of CTX-1 and IL-10 levels post treatment. There was a significant relationship between increase in the expression of MCP- and reduction in the expression of hsCRP with increase in back pain. Significant relationship was also observed between increase in the expression of MCP-1 and reduction in the expression of IL-6 with increase in leg pain. Increase in the expression of IL-8 and reduction in the expression of hsCRP was also associated with increased disability score. Inflammatory biomarkers play a significant role in the pathogenesis of LBD. CTX-1, IL-10 and IL-1 beta may be responsible for the decrease in back pain scores post treatment. There is a relationship between MCP-1, IL-6, IL-8 and hsCRP with clinical and functional assessments for LBD. Further studies will improve understanding of the pathogenesis of LBD and aid in targeted management strategies.</p

Enhancing the Enantioselectivity and Catalytic Efficiency of Esterase from Bacillus subtilis for Kinetic Resolution of l‑Menthol through Semirational Design

Enzymatic kinetic resolution is a promising way to produce l-menthol. However, the properties of the reported biocatalysts are still unsatisfactory and far from being ready for industrial application. Herein, a para-nitrobenzylesterase (pnbA) gene from Bacillus subtilis was cloned and expressed to produce l-menthol from d,l-menthyl acetate. The highest enantiomeric excess (ee) value of the product generated by pnbA was only approximately 80%, with a high conversion rate (47.8%) of d,l-menthyl acetate with the help of a cosolvent, indicating high catalytic activity but low enantioselectivity (E = 19.95). To enhance the enantioselectivity and catalytic efficiency of pnbA to d,l-menthyl acetate in an organic solvent-free system, site-directed mutagenesis was performed based on the results of molecular docking. The F314E/F315T mutant showed the best catalytic properties (E = 36.25) for d,l-menthyl acetate, with 92.11% ee and 30.58% conversion of d,l-menthyl acetate. To further improve the properties of pnbA, additional mutants were constructed based on the structure-guided triple-code saturation mutagenesis strategy. Finally, four mutants were screened for the best enantioselectivity (ee > 99%, E > 300) and catalytic efficiency at a high substrate concentration (200 g/L) without a cosolvent. This work provides several generally applicable biocatalysts for the industrial production of l-menthol

Fatty acid compositions of different species.

<p>Fatty acid compositions of different species.</p

Genome-Scale Transcriptome Analysis of the Desert Shrub <i>Artemisia sphaerocephala</i>

<div><p>Background</p><p><i>Artemisia sphaerocephala</i>, a semi-shrub belonging to the <i>Artemisia</i> genus of the <i>Compositae</i> family, is an important pioneer plant that inhabits moving and semi-stable sand dunes in the deserts and steppes of northwest and north-central China. It is very resilient in extreme environments. Additionally, its seeds have excellent nutritional value, and the abundant lipids and polysaccharides in the seeds make this plant a potential valuable source of bio-energy. However, partly due to the scarcity of genetic information, the genetic mechanisms controlling the traits and environmental adaptation capacity of <i>A</i>. <i>sphaerocephala</i> are unknown.</p><p>Results</p><p>Here, we present the first in-depth transcriptomic analysis of <i>A</i>. <i>sphaerocephala</i>. To maximize the representation of conditional transcripts, mRNA was obtained from 17 samples, including living tissues of desert-growing <i>A</i>. <i>sphaerocephala</i>, seeds germinated in the laboratory, and calli subjected to no stress (control) and high and low temperature, high and low osmotic, and salt stresses. <i>De novo</i> transcriptome assembly performed using an Illumina HiSeq 2500 platform resulted in the generation of 68,373 unigenes. We analyzed the key genes involved in the unsaturated fatty acid synthesis pathway and identified 26 <i>A</i>. <i>sphaerocephala fad2</i> genes, which is the largest <i>fad2</i> gene family reported to date. Furthermore, a set of genes responsible for resistance to extreme temperatures, salt, drought and a combination of stresses was identified.</p><p>Conclusion</p><p>The present work provides abundant genomic information for functional dissection of the important traits of <i>A</i>. <i>sphaerocephala</i> and contributes to the current understanding of molecular adaptive mechanisms of <i>A</i>. <i>sphaerocephala</i> in the desert environment. Identification of the key genes in the unsaturated fatty acid synthesis pathway could increase understanding of the biological regulatory mechanisms of fatty acid composition traits in plants and facilitate genetic manipulation of the fatty acid composition of oil crops.</p></div

Plot showing the dependence of unigene length on the number of reads assembled into the corresponding unigenes.

<p>Plot showing the dependence of unigene length on the number of reads assembled into the corresponding unigenes.</p

Summary of sequence annotation.

<p>Summary of sequence annotation.</p

Phylogenetic comparison of <i>Artemisia sphaerocephala</i> AsFAD2s with FAD2s in other plants.

<p>Note: The phylogenetic tree was generated using Mega 5.0. The GenBank accession numbers of the amino acid sequences represented in the phylogenetic tree are as follows: CtFAD2-1, AGC65498.1; CtFAD2-2, AGC65499.1; CtFAD2-3, AGC65500.1; CtFAD2-4, AGC65501.1; CtFAD2-5, AGC65502.1; CtFAD2-6, AGC65503.1; CtFAD2-7, AGC65504.1; CtFAD2-8, AGC65505.1; CtFAD2-9; AGC65506.1; CtFAD2-10, AGC65507.1; CtFAD2-11, AGC65508.1; ghFAD2, AAQ16654.1; ghDES-2, AAL37484.1; ghDES-3, ADP02395.1; ahDES-1, ACZ06072.1; ahDES-2, AHN60569.1; gmFAD2-1B, ABF84062.1; gmFAD2-4, NP_001237865.1; gmDES-1, AAX29989.1; gmDES-2, AAB00860.1; gmDES-3, NP_001238342.1; BnA.FAD2.a-1, AFJ19029.1; BnA.FAD2.a, AFJ19030.1; BnC.FAD2.a, AFJ19031.1; BnC.FAD2.b, AFJ19032.1; bnDES-1, AGV77099.1; bnDES-2, AAT02411.1; haFAD2-1, AAL68981.1; haFAD2-2, AAL68982.1; haFAD2-3, AAL68983.1; luFAD2, AFJ53087.1; and atDES, AEE85834.1 (ct, <i>Carthamus tinctorius</i>; gh, <i>Gossypium hirsutum</i>; ah, <i>Arachis hypogaea</i>; gm, <i>Glycine max</i>; bn, <i>Brassica napus</i>; ha, <i>Helianthus annuus</i>; lu, <i>Linum usitatissimum</i>; at, <i>Arabidopsis thaliana</i>; As, <i>Artemisia sphaerocephala</i>; and Ac, <i>Artemisia annua</i>).</p

Summary of transcriptome sequencing results.

<p>Summary of transcriptome sequencing results.</p

Venn diagram of stress-response unigenes.

<p>Venn diagram of stress-response unigenes.</p