Abstract:Plants tend to flower earlier if placed under stress conditions. Those stress factors include drought, high salinity, low temperature, high- or low-intensity light, and ultraviolet light. This phenomenon has been called stress-induced flowering. Stress-induced plant flowering might be helpful for species preservation. Thus, stress-induced flowering might have biological significance and should be considered as important as other plant flowering control strategy. Here, history of stress-induced flowering, metabolic regulation and molecular regulation mechanisms in plants were reviewed. Potential perspective was discussed.

Abstract:We reviewed the progress of the bio-jet fuels industry in recent years and systematically analyzed the technical routes that have been approved or in the pipeline for approval by ASTM D7566. In addition, we highlighted a novel pathway to produce drop-in fuel by near-critical hydrolysis of waste cooking oils or algal oils followed by catalytic decarboxylation. Also, we introduced the source of oils and fats feedstock and the domestic bio-jet fuel industry status during the 12th Five-Year-Plan period. Based on our own research, we discussed the prospect of the bio-jet fuel industry and future research needs.

Abstract:Hepatocellular carcinoma (HCC) is one of the common malignant tumors. HCC gene regulatory network (HCC GRN), whose nodes consist of genes, miRNAs or TFs and whose edges consist of interaction relationships of nodes, is one of the important ways to study molecular mechanism of HCC. Based on various experimental data, types of HCC GRNs could be conducted such as TF-miRNA regulatory network. Integrating the studies of HCC GRN, TF-miRNA transcriptional regulatory network performs better in identifying core genes which play important roles in network disturbances. It is a trend that gene variations and transcriptional regulatory networks should be combined, however the corresponding research is almost blank. This review summarizes the source of HCC data sources, the classification, character, and research program of HCC GRN. Finally, according to present analysis and discussion of progress and research status of HCC GRN, we provide a useful reference for researchers.

Abstract:Prodigiosin is an important natural red pigment that is produced as a secondary metabolite by microorganisms, and has great potential applications in the field of pharmaceutical development, environmental management and dye preparation. This paper reviews recent research progress in the production of prodigiosin by microbial fermentation, including discovery and modification of the prodigiosin-producing microorganisms, regulation and optimization of prodigiosin fermentation and extraction process, and resolution of biosynthetic pathway of prodigiosin and related transcriptional regulation. Finally, we discussed the future research directions in microbial production of prodigiosin.

Abstract:Immobilization of enzymes is important and widely applied in biocatalysis. Streptomyces platensis gene gox, encoding an extracellular L-glutamate oxidase (Gox), was fused to cellulose binding domain (CBDcex) from Cellulomonas fimi and the recombinant protein Gox-CBD was expressed in Escherichia coli. The fusion protein (Gox-CBD) was immobilized onto microcrystalline cellulose. The preparation conditions, binding capacity, properties and stability of the immobilized enzyme were studied. Under the condition of 4 ℃, for 1 hour, the fusion protein Gox-CBD was able to bind microcrystalline cellulose at a ratio of 9.0 mg of protein per gram of microcrystalline cellulose. Enzymatic properties of free and immobilized L-glutamic oxidase (Gox-CBD) were compared. The specific activity of the immobilized enzyme decreased, but its thermal stability increased a lot compared with that of the free Gox-CBD. After incubation at 60 ℃ for 30 min, 70% of the total activity remained whereas the free recombinant Gox completely lost its activity. The immobilized protein was tightly bound to microcrystalline cellulose at pH below 10 or more than 5 mmol/L NaCl. The fusion protein of Gox-CBD can be specifically immobilized on the microcrystalline cellulose on a single step. Therefore, our findings can provide a novel strategy for protein purification and enzyme immobilization.

Abstract:Aminoglycosides are broad-spectrum antibacterials to treat bacterial infections, especially gram-negative bacteria infections. However, aminoglycosides are losing efficacy because of the increase in antibiotic resistance and their inherent toxicity, attracting more interests in developing new aminoglycosides. Several clinically used aminoglycosides are mainly exerted by inhibition of protein synthesis through binding to bacterial rRNA. The bacterial ribosome RNA is the most currently exploited RNA drug target. Identification of new compounds that target RNAs is indispensable to fight with the growing threat that bacteria pose to human safety. In this work, we used carbohydrate microarrays to probe interactions of low molecular weight ligands with RNAs and proteins. Carbohydrate microarrays, comprising hundreds to thousands of different glycan structures on surfaces in a spatially discrete pattern, are sensitive and versatile tools to study the interactions between biological macromolecules. Herein, aminoglycosides have been immobilized onto the modified glass microscope slides and their interactions with RNAs and proteins are then measured through the labeled fluorescence. The results displayed that microarray can be used to detect the binding of aminoglycosides with three types of target molecules, including the small RNA oligonucleotide mimics of aminoglycoside binding sites in the ribosome (rRNA A-site mimics), the large group I ribozyme RNA (approximately 400 nucleotide) and certain proteins (toxicity-causing enzymes, such as DNA polymerase and phospholipase C). For rRNA A-site mimics, the fluorescence intensities of 16S rRNA is stronger than that of 18S rRNA, illustrating that as a screen technique, the microarray method can not only determine the binding affinity to RNA but also detect the specific binding to bacterial rRNA mimic. The ability to screen group I ribozyme RNA can be helpful to the discovery of new RNA therapeutic targets. Binding of immobilized aminoglycosides to toxicity-causing proteins (DNA polymerase and phospholipase C) is a new method to study of aminoglycoside toxicity. These studies lay the foundation for rapid identification of new RNA-binding ligands with strong and specific binding affinity for their desired targets.

Abstract:Hyper-osmotic stress is one of the key factors that decrease the efficiency of biological succinic acid production. To increase the osmotic stress tolerance of succinate-producing Escherichia coli, we studied the influence of IrrE, an exogenous global regulator, on cell osmotic stress resistance. Fermentation results showed that cell growth and succinic acid production by the recombinant increased under different Na+ concentrations. Meanwhile, the maximum dry cell mass, glucose consumption and succinic acid concentration increased 15.6%, 22% and 23%, respectively, when fermented in a 5-L bioreactor. Expressing IrrE improved cell resistance to hyper-osmotic stress. Further comparison of intracellular osmoprotectants (trehalose and glycerol) concentrations showed that trehalose and glycerol concentrations in the recombinant increased. This suggested that introducation of IrrE could enhance intracellular osmoprotectants accumulation which conferred cell with improved resistance to osmotic stress.

Abstract:Deficient activity of endo-1,4-beta-glucanase II (Cel5A) secreted by Trichoderma reesei is one of the challenges involved in effective cellulase saccharification of cellulosic substrates. Therefore, we expressed Cel5A in Pichia pastoris by constructing a recombinant strain. With the gene optimization based on codon bias, and the construction of expression vector pPIC9K-eg2, the optimized gene was electro-transformed into P. pastoris GS115 to form transformants. Then, a high Cel5A activity producing recombinant, namely P. pastoris GS115-EG Ⅱ, was selected on G-418 resistant plates, followed by shake-flask cultivation. Enzyme characterization showed that the recombinant Cel5A reacted optimally at pH 4.5 and 60 ℃, with 50 kDa of molecular weight, preferentially degrading amorphous cellulose. Recombinant Cel5A was not significantly different from the native T. reesei Cel5A. Moreover, a shake-flask fermentation of the recombinant strain was optimized as below: incubation temperature 28 ℃, initial pH 5.0, inoculum volume 2%, methanol addition (per 24 h) 1.5% (V/V), sorbitol addition (per 24 h) 4 g/L and Tween 80 4 g/L. Under above optimized condition, the recombinant produced 24.0 U/mL of the Cel5A after 192 h fermentation. When incubated in a 5 L fermentation, Cel5A enzyme activity reached 270.9 U/mL at 180 h, with 4.16 g/L of the total protein. The study indicates that the recombinant strain P. pastoris GS115-EG Ⅱ is extremely suitable for heterologous expression of T. reesei cellulase Cel5A. And the recombinant Cel5A can be used as an alternative to the native T. reesei Cel5A in development of a commercially relevant enzyme based biorefinery process.

Abstract:Basic helix loop helix (bHLH) transcription factor plays an important role in biological processes. Bmsage is a class of bHLH transcription factor highly expressed in the silk gland of Bombyx mori, which is not only involved in the developmental regulation of the silk gland cells at the embryonic period, but also plays a crucial regulatory role during the synthesis of silk protein. However, currently, much of the property and structure of Bmsage is still remained unknown. To study the property, structure and biological role of Bmsage, we constructed several prokaryotic expression vectors of Bmsage fused with NusA, MBP, SUMO, Trx and His tags, respectively, then screened and determined the best soluble expression vector and condition of Bmsage in Escherichia coli combining with the induction temperature and IPTG concentration, and further purified the recombinant Bmsage by Ni-column affinity chromatography according to the established expression condition and characterized its secondary structure using circular dichroism spectra. The results showed that NusA and MBP could significantly enhance the soluble expression of Bmsage in E. coli, but it was difficult to separate Bmsage from these tags. SUMO could not only increase the soluble expression of Bmsage in E. coli to a certain degree, but also be effectively separated from Bmsage. Other tags did not effectively promote the soluble expression of Bmsage in E. coli. Circular dichroism spectra showed that the purified Bmsage had well-defined α-helix structure in solution, indicating that SUMO may promote the correct folding of Bmsage into native-like structure. These work not only establish a foundation for further study of the property, structure and function of Bmsage, but also provide a reference for the expression and purification of other similar proteins.

Abstract:Scavenger receptor class B is involved in various indispensable physiological processes, like the formation and inhibition of atherosclerosis or other cardiovascular diseases, innate immune defense and the removal of apoptotic cells. Here, we cloned BmSCRB8, a member of scavenger receptor class B in silkworm. We obtained the full-length cDNA sequence of BmSCRB8 by rapid amplification of cDNA ends (RACE), including 2 668 bp. The ORF of BmSCRB8 is 1 704 bp, encoding 567 amino acids. Online software prediction indicated that the molecular weight of BmSCRB8 is 63.87 kDa and the isoelectric point (pI) is 6.06. The space-time expression profile of BmSCRB8 was detected by reverse transcription PCR (RT-PCR), which implicated that BmSCRB8 is extensively expressed in each tissue and at each stage of blood. In addition, BmSCRB8 is highest expressed in fat body of silkworm, and is highly expressed in metamorphosis periods. Anti-BmSCRB8 polyclonal antibody was generated through prokaryotic expression, protein purification and mice immunization. Simultaneously, we constructed BmSCRB8 eukaryotic vector and then transfected embryonic cell line of silkworm. Immunofluorescence and overexpression showed that BmSCRB8 expressed specifically in membrane. Western blotting demonstrated that BmSCRB8 protein can be specifically recognized by anti-serum generated after mice immunization.

Abstract:To study the effects and mechanisms of interleukin-8 (IL-8) on the proliferation and autophagy of human bone marrow mesenchymal stem cells (hBMSC) under hypoxic condition. In the hypoxia model, we set the non-stimulated hBMSC as the hypoxia control group; the hBMSC stimulated by 100 μmol/L human IL-8 as the IL-8 group; the hBMSC stimulated by 50 μmol/L MK2206 (Akt protein inhibitor) and 100μmol/L IL-8 as the Akt inhibitor group; and the normal cultured hBMSC as the normal control group. The experiments of EdU cell proliferation and TUNEL apoptosis were respectively used to detect the number of positive cells that were labeled by EdU and apoptosis in each group, and Western blotting and ELISA were used respectively to detect the expression of autophagy protein (LC-3), Akt/STAT3 and other proteins in each group. The results indicated that the proliferation and autophagy of hBMSC in IL-8 group was higher than that in hypoxia control group and Akt inhibitor group, and the apoptosis rate in IL-8 group decreased. These results and the high expression of Akt, STAT3 and VEGF protein of IL-8 group show that under the hypoxic condition, IL-8 played a protective role on MSC through the Akt-STAT3 pathway. It had important significance in the protection of MSC against the injury due to ischemia and hypoxia, and promoted the application of MSC in regenerative medicine.

Abstract:Flap endonuclease 1 (FEN1) is an endonuclease that catalyzes invasive reaction. It can be used in signal-amplification reaction-based nucleic acid assay. However, the application of FEN1 is hampered due to the lack of detailed protocols to express and purify the enzyme, and to quantify the enzyme activity. In this paper, the DNA fragment coding the gene of FEN1 from Archaeoglobus fulgidus was synthesized, and inserted into the plasmid of pET24a(+) to express recombinant FEN1 with His-tag. After optimizing the expression, detailed expression protocol of FEN1 was obtained by culturing the recombinant E. coli at 37 ℃ with 200 r/min of shaking for 8 h, followed by inducing with 0.05 mmol/L IPTG at 37 ℃ for 11 h. The purified recombinant FEN1 with the molecular mass of 38 kDa was obtained by Ni-affinity chromatography. Moreover, we developed a accurate quantification method with fluorescence-labelled probes. Finally, the recombinant FEN1 was used in real-time PCR coupled with high specific invader assay for aldh2 gene genotyping to obtain the correct typing results, indicating that the recombinant FEN1 can be used in gene polymorphism detection. We provide a reliable enzyme for developing invasive reaction-based nucleic acid assay.

Abstract:Ubiquitination is one of the most major post-translational modifications playing important role in regulation of intra-cellular proteins’ stability, degradation, localization and biological activity. However, these proteins are difficult to be detected due to their low abundance, short half-life. In this study, ubiquitin-binding domains (UBDs) were constructed to purify the ubiquitinated proteins from Hep3B cells. Ubiquitinated proteins and sites were detected by LC-MS/MS. A total of 1 900 potential ubiquitinated proteins were identified. Among them, 158 ubiquitinated sites were identified, belonging to 102 proteins. Bioinformatics analysis revealed that the enriched pathways of ubiquitinated proteins were closely related to tumor occurrence and development. The dysfunction of ubiquitin-proteasome has a high correlation with cell signaling and extracellular matrix changing in tumor cells.

Abstract:A mammalian nonclassical secretion sequence derived from mouse Engrailed2 homeoprotein (En2) was used to direct the secretion of the enhanced green fluorescent protein from Pichia pastoris. This signal peptide conferred the transport of enhanced green fluorescent protein into periplasm through an endoplasmic reticulum-golgi independent pathway, without inducing severe unfolded protein response as compared with Saccharomyces cerevisae α-factor preprosequence. This study implies that this mammalian nonclassical signal peptide could be developed as a useful tool for delivering cargoes to the cell surface of yeast.

Abstract:To quantify the transcriptional activity of NF-κB and to screen drugs related to the regulation of NF-κB activation, we constructed a recombinant plasmid through deleting the original CMV promoter of retrovirus vector pQCXIP and inserting the NF-κB enhancer and NanoLuc luciferase sequence into the vector. Then, using the recombinant plasmid we constructed a cell line in which the expression of NanoLuc luciferase (NLuc) was regulated by NF-κB. The inserted sequences were verified by restriction endonuclease digestion and sequencing. Tumor necrosis factor-α (TNF-α), an NF-κB activator, acted on the constructed NLuc cell line and leaded to the specific luciferase reaction. The luciferase reaction showed a fine time and dose dependence to the TNF-α stimulation, indicating the successful construction of the NF-κB regulated NLuc-expressing cell line. Besides, the NF-κB inhibitor, triptolide, reduced the expression of NLuc in a dose-dependent way. The constructed reporter system in this study could be applied in the quantification of the NF-κB transcriptional activity and in the NF-κB regulation-related drug screening.