Phenazine-1-carboxylic acid production in a chromosomally non-scar triple-deleted mutant Pseudomonas aeruginosa using statistical experimental designs to optimize yield

We constructed a non-scar triple-deleted mutant Pseudomonas aeruginosa to improve phenazine-1-carboxylic acid (PCA) yield and then optimized the culture conditions for PCA production. Using a non-scar deletion strategy, the 5′-untranslated region of the phz1 gene cluster and two genes, phzM and phzS, were knocked out of the P. aeruginosa strain M18 genome. The potential ability for high-yield PCA production in this triple-deleted mutant M18MSU1 was successfully realized by using statistical experimental designs. A 2^5–1 fractional factorial design was used to show that the three culture components of soybean meal, corn steep liquor and ethanol had the most significant effect on PCA production. Using a central composite design, the concentration of the three components was optimized. The maximum PCA production was predicted to be 4,725.1 mg/L. With the optimal medium containing soybean meal 74.25 g/L, corn steep liquor 13.01 g/L and ethanol 21.84 ml/L, a PCA production of 4,771.2 mg/L was obtained in the validation experiments, which was nearly twofold of that before optimization and tenfold of that in the wild-type strain. This non-scar triple-deleted mutant M18MSU1 may be a suitable strain for industrial production of this biologically synthesized fungicide due to its high PCA production, presumed safety, thermal adaptability and cost-effectiveness.     

The InR/Akt/TORC1 Growth-Promoting Signaling Negatively Regulates JAK/STAT Activity and Migratory Cell Fate during Morphogenesis

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Changes in microbial biomass,community composition and diversity,and functioning with soil depth in two alpine ecosystems on the Tibetan plateau

Plant and Soil - Plant P acquisition strategies are driven by multiple belowground morphological and physiological traits as well as interactions among these traits. This study aimed to...     

Association of myostatin deficiency with collagen related disease-umbilical hernia and tippy toe standing in pigs

Transgenic Research - Herein, we investigate the high incidence of umbilical hernia and tippy-toe standing and their underlying changes in gene expression and proliferation in myostatin knockout...     

ITMSQ: A software tool for N‐ and C‐terminal fragment ion pairs based isobaric tandem mass spectrometry quantification

Tandem MS (MS2) quantification using the series of N‐ and C‐terminal fragment ion pairs generated from isobaric‐labelled peptides was recently considered an accurate strategy in quantitative proteomics. However, the presence of multiplexed terminal fragment ion in MS2 spectra may reduce the efficiency of peptide identification, resulting in lower identification scores or even incorrect assignments. To address this issue, we developed a quantitative software tool, denoted isobaric tandem MS quantification (ITMSQ), to improve N‐ and C‐terminal fragment ion pairs based isobaric MS2 quantification. A spectrum splitting module was designed to separate the MS2 spectra from different samples, increasing the accuracy of both identification and quantification. ITMSQ offers a convenient interface through which parameters can be changed along with the labelling method, and the result files and all of the intermediate files can be exported. We performed an analysis of in vivo terminal amino acid labelling labelled HeLa samples and found that the numbers of quantified proteins and peptides increased by 13.64 and 27.52% after spectrum splitting, respectively. In conclusion, ITMSQ provides an accurate and reliable quantitative solutionfor N‐ and C‐terminal fragment ion pairs based isobaric MS2 quantitative methods.     

Procyanidin B1 promotes in vitro maturation of pig oocytes by reducing oxidative stress

Oxidative stress negatively affects the in vitro maturation (IVM) of oocytes. Procyanidin B1 (PB1) is a natural polyphenolic compound that has antioxidant properties. In this study, we investigated the effect of PB1 supplementation during IVM of porcine oocytes. Treatment with 100 μM PB1 significantly increased the MII oocytes rate (p <0.05), the parthenogenetic (PA) blastocyst rate (p <0.01) and the total cell number in the PA blastocyst (p < 0.01) which were cultured in regular in vitro culture (IVC) medium. The PA blastocyst rate of regular MII oocytes activated and cultured in IVC medium supplemented with 100 and 150 μM PB1 significantly increased compared with control (p < 0.01 and p < 0.05). We also evaluated the reactive oxygen species (ROS) levels, mitochondrial membrane potential (Δψm) levels, glutathione (GSH) levels, and apoptotic levels in MII oocytes and cumulus cells following 100 μM PB1 treatment. The results showed that the PB1 supplementation decreased ROS production and apoptotic levels. In addition, PB1 was found to increase Δψm levels and GSH levels. In conclusion, PB1 inhibited apoptosis of oocytes and cumulus cells by reducing oxidative stress. Moreover, PB1 improved the quality of oocytes and promoted PA embryo development. Taken together, our results suggest that PB1 is a promising antioxidant additive for IVM of oocytes.