Degradation behavior of chitosan chains in the 'green' synthesis of gold nanoparticles

The degradation behavior of chitosan chains in the synthesis of Au nanoparticles by a 'green' method was investigated in this paper for the first time. UV-vis absorption spectra suggested the formation of Au nanoparticles and TEM images showed that their sizes were between 10 and 50nm. During the process of synthesis, the intrinsic viscosity [eta] of chitosan was observed to decrease gradually, implying that the chitosan chains degraded under the reaction conditions. Further studies showed that the degree of degradation of the chitosan chains was changed with different reaction temperatures, reactant ratios, and the molecular weights of chitosan.     

N-terminal acetylation in paenibacillin, a novel lantibiotic

N-terminal acetylation was uncovered in paenibacillin, a novel lantibiotic recently reported as a product of Paenibacillus polymyxa OSY-DF. This N-terminal modification is unprecedented among bacteria-derived antimicrobial peptides and further illustrates the broad range of modifications that can occur in lantibiotics. Additionally, the primary structure of paenibacillin has been finally determined unequivocally by the extensive NMR analysis taken together with previous MS/MS results. These analyses revealed the structure of paenibacillin as one of the most post-translationally modified lantibiotics.     

Site-directed mutagenesis by combination of homologous recombination and DpnI digestion of the plasmid template in Escherichia coli

A rapid site-directed mutagenesis strategy using homologous recombination and DpnI digestion of the template in Escherichia coli is described. Briefly, inverse polymerase chain reaction amplification of the entire circular plasmid was performed by mutagenic primers with overlapping sequences ( approximately 15 bp) for generating PCR products with approximately 15 bp of homology on the terminal ends. On direct transformation of the amplified PCR products into restriction endonuclease DpnI-expressing E. coli BUNDpnI, homologous recombination occurs in E. coli while the original templates are removed via DpnI digestion in vivo, thus yielding clones harboring mutated circular plasmids. Nearly 100% efficiency was attained when this strategy was used to modify DNA sequences.     

Androgen receptor suppresses vasculogenic mimicry in hepatocellular carcinoma via circRNA7/miRNA7‐5p/VE‐cadherin/Notch4 signalling

Androgen receptor (AR) can suppress hepatocellular carcinoma (HCC) invasion and metastasis at an advanced stage. Vasculogenic mimicry (VM), a new vascularization pattern by which tumour tissues nourish themselves, is correlated with tumour progression and metastasis. Here, we investigated the effect of AR on the formation of VM and its mechanism in HCC. The results suggested that AR could down‐regulate circular RNA (circRNA) 7, up‐regulate micro RNA (miRNA) 7‐5p, and suppress the formation of VM in HCC Small hairpin circR7 (ShcircR7) could reverse the impact on VM and expression of VE‐cadherin and Notch4 increased by small interfering AR (shAR) in HCC, while inhibition of miR‐7‐5p blocked the formation of VM and expression of VE‐cadherin and Notch4 decreased by AR overexpression (oeAR) in HCC. Mechanism dissection demonstrated that AR could directly target the circR7 host gene promoter to suppress circR7, and miR‐7‐5p might directly target the VE‐cadherin and Notch4 3′UTR to suppress their expression in HCC. In addition, knockdown of Notch4 and/or VE‐cadherin revealed that shVE‐cadherin or shNotch4 alone could partially reverse the formation of HCC VM, while shVE‐cadherin and shNotch4 together could completely suppress the formation of HCC VM. Those results indicate that AR could suppress the formation of HCC VM by down‐regulating circRNA7/miRNA7‐5p/VE‐Cadherin/Notch4 signals in HCC, which will help in the design of novel therapies against HCC.     

Upregulation of the solute carrier family 7 genes is indicative of poor prognosis in papillary thyroid carcinoma

Background

The solute carrier (SLC) 7 family genes comprise 14 members and function as cationic amino acid/glycoprotein transporters in many cells, they are essential for the maintenance of amino acid nutrition and survival of tumor cells. This study was conducted to analyze the associations of SLC7 family gene expression with mortality in papillary thyroid carcinoma (PTC).

Methods

Clinical features, somatic mutations, and SLC7 family gene expression data were downloaded from The Cancer Genome Atlas database. Linear regression model analysis was performed to analyze the correlations between SLC7 family gene expression and clinicopathologic features. Kaplan-Meier survival and logistic regression analyses were performed to characterize the associations between gene expression and patients’ overall survival.

Results

Patient mortality was negatively associated with age and tumor size but positively increased cancer stage and absence of thyroiditis in PTC patients. Kaplan-Meier survival analysis indicated that patients with high SLC7A3, SLC7A5, and SLC7A11 expression levels exhibited poorer survival than those with low SLC7A3, SLC7A5, and SLC7A11 expression levels (P?<?0.05 for all cases). Logistic regression analysis showed that SLC7A3, SLC7A5, and SLC7A11 were associated with increased mortality (odds ratio [OR] 8.61, 95% confidence interval [CI] 2.3–55.91; OR 3.87, 95% CI 1.18–17.31; and OR 3.87, 95% CI 1.18–17.31, respectively.

Conclusion

Upregulation of SLC7A3, SLC7A5, and SLC7A11 expression was associated with poor prognosis in PTC patients, and SLC7 gene expression levels are potentially useful prognostic biomarkers.

     

Key factors identified by proteomic analysis in maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) seedlings’ response to long-term exposure to different phosphate levels

Background

Maize seedlings are constantly exposed to inorganic phosphate (Pi)-limited environments. To understand how maize cope with low Pi (LP) and high Pi (HP) conditions, physiological and global proteomic analysis of QXN233 genotype were performed under the long-term Pi starvation and supplementation.

Methods

We investigated the physiological response of QXN233 genotype to LP and HP conditions and detected the changes in ion fluxes by non-invasive micro-test technology and gene expression by quantitative real-time polymerase chain reaction. QXN233 was further assessed using vermiculite assay, and then proteins were isolated and identified by nano-liquid chromatography-mass spectrometry.

Results

A negative relationship was observed between Na⁺ and Pi, and Na⁺ efflux was enhanced under HP condition. Furthermore, a total of 681 and 1374 were identified in the leaves and roots, respectively, which were mostly involved in metabolism, ion transport, and stress response. Importantly, several key Pi transporters were identified for breeding potential. Several ion transporters demonstrated an elaborate interplay between Pi and other ions, together contributing to the growth of QXN233 seedlings.

Conclusion

The results from this study provide insights into the response of maize seedlings to long-term Pi exposure.

     

Production optimization for concentration and volume-limited fed-batch reactors in biochemical processes

Bioprocess and Biosystems Engineering - Since a very slight violation of constraint could cause process safety and product quality problems in biochemical processes, an adaptive approach of...     

Synthesis and Biological Evaluation of a Series of Novel Celastrol Derivatives with Amino Acid Chain

The synthesis of celastrol analogues containing amino acid ester at the C(29) position and their evaluation for cytotoxic activities in vitro were reported. The MTT test showed that a set of derivatives with lower IC₅₀ values than that of the positive control group cisplatin and the parent compound celastrol, which exhibited greater antiproliferative activities. The most potent title compounds 2a and 2e exhibited cytotoxic activities in vitro against HeLa and A549 cell lines with IC₅₀ values of 0.371 and 0.237 μm , 0.235 and 0.109 μm , respectively. The apoptosis assay demonstrated that 2a and 2e can induces of A549 cell apoptosis in low concentrations. These results showed that 2a and 2e may be promising for further research as antitumor agents.