Optimization of microbial cell factories for astaxanthin production: Biosynthesis and regulations, engineering strategies and fermentation optimization strategies.

The global market demand for natural astaxanthin is rapidly increasing owing to its safety, the potential health benefits, and the diverse applications in food and pharmaceutical industries. The major native producers of natural astaxanthin on industrial scale are the alga Haematococcus pluvialis and the yeast Xanthopyllomyces dendrorhous. However, the natural production via these native producers is facing challenges of limited yield and high cost of cultivation and extraction. Alternatively, astaxanthin production via metabolically engineered non-native microbial cell factories such as Escherichia coli, Saccharomyces cerevisiae and Yarrowia lipolytica is another promising strategy to overcome these limitations. In this review we summarize the recent scientific and biotechnological progresses on astaxanthin biosynthetic pathways, transcriptional regulations, the interrelation with lipid metabolism, engineering strategies as well as fermentation process control in major native and non-native astaxanthin producers. These progresses illuminate the prospects of producing astaxanthin by microbial cell factories on industrial scale.

Preparation of p-Phenylenediamine Modified Graphene Foam/Polyaniline@Epoxy Composite with Superior Thermal and EMI Shielding Performance.

With the development of integrated devices, the local hot spot has become a critical problem to guarantee the working efficiency and the stability. In this work, we proposed an innovative approach to deliver graphene foam/polyaniline@epoxy composites (GF/PANI@EP) with improvement in the thermal and mechanical property performance. The graphene foam was firstly modified by the grafting strategy of p-phenylenediamine to anchor reactive sites for further in-situ polymerization of PANI resulting in a conductive network. The thermal conductivity (κ) and electromagnetic interference shielding (EMI) performance of the optimized GF/PANI4:1@EP is significantly enhanced by 238% and 1184%, respectively, compared to that of pristine EP with superior reduced modulus and hardness. Such a method to deliver GF composites can not only solve the agglomeration problem in traditional high content filler casting process, but also provides an effective way to build up conductive network with low density for thermal management of electronic devices.

Gene Cascade Shift and Pathway Enrichment in Rat Kidney Induced by Acarbose Through Comparative Analysis.

Acarbose is an effective anti-diabetic drug to treat type 2 diabetes mellitus (T2DM), a chronic degenerative metabolic disease caused by insulin resistance. The beneficial effects of acarbose on blood sugar control in T2DM patients have been confirmed by many studies. However, the effect of acarbose on patient kidney has yet to be fully elucidated. In this study, we report in detail the gene expression cascade shift, pathway and module enrichment, and interrelation network in acarbose-treated Rattus norvegicus kidneys based on the in-depth analysis of the GSE59913 microarray dataset. The significantly differentially expressed genes (DEGs) in the kidneys of acarbose-treated rats were initially screened out by comparative analysis. The enriched pathways for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were further identified. The protein-protein interaction (PPI) analysis for DEGs was achieved through the STRING database mining. Pathway interrelation and hub genes for enriched pathways were further examined to uncover key biological effects of acarbose. Results revealed 44 significantly up-regulated genes and 86 significantly down-regulated genes (130 significant differential genes in total) in acarbose-treated rat kidneys. Lipid metabolism pathways were considerably improved by acarbose, and the physical conditions in chronic kidney disease (CKD) patients were improved possibly through the increase of the level of high-density lipoprotein (HDL) by lecithin-cholesterol acyl-transferase (LCAT). These findings suggested that acarbose may serve as an ideal drug for CKD patients, since it not only protects the kidney, but also may relieve the complications caused by CKD.

Integrated bioinformatics analyses identified SCL3-induced regulatory network in Arabidopsis thaliana roots.

OBJECTIVES: To uncover key genes and pathways regulated by SCL3, a GRAS transcription factor, in the context of gibberellin (GA) in the roots of the model plant Arabidopsis thaliana. RESULTS: Gene expression profiles of ga1-3 mutant and ga1-3 and scl3 double mutant are considerably similar to each other, revealed by Principal Component Analysis (PCA). More than 400 significantly Differentially Expressed Genes (DEGs) among the Arabidopsis thaliana roots of ga1-3 mutant, ga1-3 and scl3 double mutant and GA loss/SCL3 gain mutant were uncovered by comprehensive bioinformatics analyses. Protein synthesis pathway, including RPL proteins, RPS proteins, etc., and flavonoid biosynthesis pathway, including TT4, F3H, TT5, CHIL, etc. were significantly increased when SCL3 expression was higher than normal by means of pathway enrichment analysis and protein-protein interaction analysis, which is further supported by comparison analyses between wild type samples and SCL3 overexpressed roots. CONCLUSION: Protein synthesis and flavonoid biosynthesis were regulated by SCL3 in the context of GA in Arabidopsis thaliana root system identified by comprehensive bioinformatic analyses.

In situ polymerization of graphene-polyaniline@polyimide composite films with high EMI shielding and electrical properties.

With the increasing demands of the electronics industry, electromagnetic interference (EMI) shielding has become a critical issue that severely restricts the application of devices. In this work, we have proposed a "non-covalent welding" method to fabricate graphene-polyaniline (Gr-PANI) composite fillers. The Gr sheets are welded with PANI via π-π non-covalent interactions. Furthermore, a flexible polyimide (PI) composite film with superior EMI shielding effectiveness is prepared by in situ polymerization. The 40% content of Gr-PANI10:1 (the mass ratio of Gr to PANI is 10 : 1) shows a superior electrical conductivity (σ) as high as 2.1 ± 0.1 S cm-1, 1.45 times higher than that of Gr@PI film at the same loading. Moreover, the total shielding effectiveness (SET) of EMI of the Gr-PANI10:1@PI reaches ∼21.3 dB and an extremely high specific shielding effectiveness value (SSE) of 4096.2 dB cm2 g-1 is achieved. Such a "non-covalent welding" approach provides a facile strategy to prepare high-performance PI-based materials for efficient EMI shielding.