Glycolic acid-based deep eutectic solvents boosting co-production of xylo-oligomers and fermentable sugars from corncob and the related kinetic mechanism.

BACKGROUND: Xylo-oligomers are a kind of high value-added products in biomass fractionation. Although there are several chemical methods to obtain xylo-oligomers from biomass, the reports about the deep eutectic solvents (DESs)-mediated co-production of xylo-oligomers and fermentable sugars and the related kinetic mechanism are limited. RESULTS: In this work, glycolic acid-based DESs were used to obtain xylo-oligomers from corncob. The highest xylo-oligomers yield of 65.9% was achieved at 120 °C for 20 min, of which the functional xylo-oligosaccharides (XOSs, DP 2-5) accounted for up to 31.8%. Meanwhile, the enzymatic digestion of cellulose and xylan in residues reached 81.0% and 95.5%, respectively. Moreover, the addition of metal inorganic salts significantly accelerated the hydrolysis of xylan and even the degradation of xylo-oligomers in DES, thus resulting in higher selectivity of xylan removal. AlCl3 showed the strongest synergistic effect with DES on accelerating the processes, while FeCl2 is best one for xylo-oligomers accumulation, affording the highest xylo-oligomers yield of 66.1% for only 10 min. Furthermore, the kinetic study indicates that the 'potential hydrolysis degree' model could well describe the xylan hydrolysis processes and glycolic acid/lactic acid (3:1) is a promising solvent for xylo-oligomers production, in particular, it worked well with FeCl2 for the excellent accumulation of xylo-oligomers. CONCLUSIONS: Glycolic acid-based deep eutectic solvents can be successfully applied in corncob fractionation with excellent xylo-oligomers and fermentable sugars yields on mild conditions, and the large amount of xylo-oligosaccharides accumulation could be achieved by specific process controlling. The strategies established here can be useful for developing high-valued products from biomass.

Expression of Bim, Bax and Bak in the process of gingipain-induced osteoblast apoptosis / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To establish osteoblast apoptosis model induced by gingipains, and to examine the expression of pro-apoptotic protein Bcl-2 interacting mediator (Bim), Bcl-2 associated X protein (Bax) and Bcl-2 antagonist/killer (Bak).</p><p><b>METHODS</b>Gingipain and gingipain acticity were extracted and measured. Mouse osteoblast cell line MC3T3-E1 cells were cultured in the presence of 0.453, 0.906, 1.812 U/L gingipains for 0, 16, 24 and 48 h. Apoptosis was examined by 4',6-diamidino-2-phenylindole (DAPI) staining or annexin V/propidine iodide (PI) staining.Protein expression of Bim, Bax and Bak was determined by Western blotting after osteoblasts were cultured with 1.812 U/L gingipain for 0, 4, 8, 16, 24 and 48 h. Osteoblasts were cultured with 1.812 U/L gingipain which had been inhibited with N-alpha-tosyl L-lysyl-chlorom ethylketone (TLCK). Western blotting was used to detect Bim expression and DAPI staining to measure apoptosis.</p><p><b>RESULTS</b>Arginine-specific proteinases (Rgp) activity was (18.11 ± 2.11) U/L and specific proteinases (Kgp) was (1.02 ± 0.25) U/L. Percentage of osteoblast apoptosis induced by 1.812 U/L gingipain rose to (6.31 ± 0.37)% after 16 h, and reached (11.20 ± 0.35)% at 24 h and (10.80 ± 0.46)% after 48 h with DAPI staining. Annexin V/PI staining supported the result from DAPI staining.Bim protein level increased during osteoblast apoptosis, the relative fold rose to (0.31 ± 0.03) after 4 h (about 2 fold compared to control), peaking at 24 h (0.57 ± 0.05, 3-4 fold compared to control). Proteinase inhibitor TLCK effectively blocked the activity of gingipain and inhibited up-regulation of Bim induced by gingipains from (0.58 ± 0.04) to (0.14 ± 0.03). The percentage of osteoblast apoptosis decreased from (11.20 ± 0.35)% to (4.31 ± 0.38)% in the presence of TLCK. Expression of Bax remained unchanged when cells were cultured with or without gingipains. Bak was under the detectable level in MC3T3-E1.</p><p><b>CONCLUSIONS</b>1.812 U/L gingipains induced osteoblast apoptosis. Protein expression of Bim was up-regulated during cell apoptosis and was down-regulated when gingipain inhibited with TLCK, suggesting that Bim was involved in osteoblast apoptosis induced by gingipain. Inhibition of Bim protein expression protected osteoblast from apoptosis.</p>

Preliminary study of HPV16 L1/E6-E7 chimeric recombinant DNA vaccine plasmid construction and expression in CHO cell / 中华实验和临床病毒学杂志

<p><b>BACKGROUND</b>To develop HPV16 L1/E6 and L1/E7 prophylactic and therapeutic DNA vaccines.</p><p><b>METHODS</b>The nucleotides within HPV 16 E6 and E7 genes, which are responsible for viral transforming activity, were mutated by mega primer site-directed mutagenesis method. The correctly mutated E6 and E7 fragments were separately cloned into an eukaryotic expression vector pVAX1, together with HPV 16 L1 gene, generating chimeric recombinants plasmids 1MpVAX1-L1E6, 2MpVAX1-L1E6, 1MpVAX1-L1E7, 2MpVAX1-L1E7 and 3MpVAX1-L1E7. CHO cells were transiently transfected with the individual DNA vaccines by calcium phosphate method. Target protein expressions in the extracts of the transfected cell lines were measured by ELISA and immunohistochemistry, with HPV 16 L1 and E6 specific monoclonal antibodies.</p><p><b>RESULTS</b>ELISA showed the P/N ratios in the cell extracts transfected with L1E6 and L1E7 plasmids were greater than 2.1. Immunohistochemistry revealed brownish precipitant signal in cytoplasm and nuclei of the transfected cells.</p><p><b>CONCLUSIONS</b>Successful constructions of prophylactic and therapeutic DNA vaccine plasmids may be useful for future animal experiment and clinical trial.</p>

Cloning and polymorphism analysis of prtH gene from Porphyromonas gingivalis / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To clone the prtH gene from Porphyromonas gingivalis (P.g) ATCC 33277 and analyze the polymorphism of prtH gene from 5 strains of P.g in order to explore the relationship between P.g and periodontitis.</p><p><b>METHODS</b>Using PCR, the prtH was amplified and cloned into pGEM-T vector. To illustrate the prtH polymorphism among P.g strains, the genomic DNAs were extracted and screened by PCR with three pairs of specific primers, dot blot and Southern blot hybridization using the biotin-labeled prtH sequence as probe.</p><p><b>RESULTS</b>Recombinant DNA pGEM-T- prtH was verified by restriction endonuclease and sequence assay. Strain W 381 and ATCC 33277 showed the identical results in PCR and hybridization assays, whereas strain ATCC 49417 and 14-3-2 revealed individual hybridization patterns. Strain 47A-1 seemed even not to contain prtH gene.</p><p><b>CONCLUSIONS</b>Different prtH gene sequences exist in different P.g strains. This polymorphism may indicate various potential virulent effects during the infection and pathogenesis. Established PCR protocol is sensitive for identification of prtH gene.</p>