Gene expression profiles in different stem internodes reveal the genetic regulation of primary and secondary stem development in <Emphasis Type="Italic">Betula platyphylla</Emphasis>

Secondary growth of stems is an important process for the radial increase of trees. To gain an insight into the molecular mechanisms underlying stem development from primary to secondary growth and to provide information for molecular research and breeding in Betula platyphylla (birch), the gene expression profiles of material from the first, third, and fifth internodes (IN) of 3-month-old seedlings were analyzed. Compared with the first IN, 177 genes were up-regulated and 157 genes down-regulated in the third IN; in the fifth IN, 180 genes were up-regulated and 275 genes were down-regulated. The expressions of 24 genes were up-regulated and 6 genes were down-regulated in the fifth IN relative to the third IN. The differentially expressed genes were annotated as having roles in cambium, xylem, and phloem development and formation; including cell wall expansion, cellulose biosynthesis, lignin biosynthesis and deposition, xylem extension, cell wall modification, and growth hormone responses. The expressions of genes related to cell wall expansion and cellulose biosynthesis in the primary cell wall were down-regulated in the third and fifth IN relative to the first IN. Genes involved in lignin biosynthesis, xylem extension, and cellulose synthesis in the secondary cell wall were up-regulated in the third and fifth IN relative to the first IN. These results described the patterns of gene expression during stem development in birch and provided candidate genes for further functional characterization.     

3D‐Printed Cathodes of LiMn1−xFexPO4 Nanocrystals Achieve Both Ultrahigh Rate and High Capacity for Advanced Lithium‐Ion Battery

A 3D‐printing technology and printed 3D lithium‐ion batteries (3D‐printed LIBs) based on LiMn_0.21Fe_0.79PO₄@C (LMFP) nanocrystal cathodes are developed to achieve both ultrahigh rate and high capacity. Coin cells with 3D‐printed cathodes show impressive electrochemical performance: a capacity of 108.45 mAh g^?1 at 100 C and a reversible capacity of 150.21 mAh g^?1 at 10 C after 1000 cycles. In combination with simulation using a pseudo 2D hidden Markov model and experimental data of 3D‐printed and traditional electrodes, for the first time deep insight into how to achieve the ultrahigh rate performance for a cathode with LMFP nanocrystals is obtained. It is estimated that the Li‐ion diffusion in LMFP nanocrystal is not the rate‐limitation step for the rate to 100 C, however, that the electrolyte diffusion factors, such as solution intrinsic diffusion coefficient, efficiency porosity, and electrode thickness, will dominate ultrahigh rate performance of the cathode. Furthermore, the calculations indicate that the above factors play important roles in the equivalent diffusion coefficient with the electrode beyond a certain thickness, which determines the whole kinetic process in LIBs. This fundamental study should provide helpful guidance for future design of LIBs with superior electrochemical performance.     

Conservation genetics of rare trees restricted to subtropical montane cloud forests in southern China: a case study from <Emphasis Type="Italic">Quercus arbutifolia</Emphasis> (Fagaceae)

Montane cloud forests (MCFs), with their isolated nature, offer excellent opportunities to study the long-term effects of habitat fragmentation and the impacts of climate change. Quercus arbutifolia is a rare oak in MCFs of southern China and Vietnam. Its isolated populations, small population size and unique ecological niche make this species vulnerable to climate change and habitat loss. In this study, we used chloroplast (cpDNA) and nuclear (ITS) DNA sequences to investigate genetic divergence patterns and demographic history of five of the six known populations of Q. arbutifolia. Considering its small population size and fragmentation, Q. arbutifolia has unexpectedly high genetic diversity. The time since the most recent common ancestor of all cpDNA haplotypes was c. 10.25 Ma, and the rapid diversification of haplotypes occurred during the Quaternary. The maximum clade credibility chronogram of cpDNA haplotypes suggests that the DM population (Daming Mountain, Guangxi province) diverged early and rapidly became isolated from other populations. The Pearl River drainage system may have been the main geographic barrier between DM and other populations since the late Miocene. ITS data suggests that population expansion occurred during the last interglacial of the Quaternary. The combined effects of pre-Quaternary and Quaternary climatic and geological changes were the main drivers to the current genetic diversity and distribution pattern of Q. arbutifolia. Because of the high between-population genetic differentiation and high within-population genetic diversity of Q. arbutifolia, conservation efforts should be implemented for all populations, but if conservation resources are limited, populations DM, YZ (Mang Mountain, Hunan province) and ZZ (Daqin Mountain, Fujian province) should have priority.     

Possible target‐related proteins and signal network of bufalin in A549 cells suggested by both iTRAQ‐based and label‐free proteomic analysis

Bufalin (BF) exhibited antiproliferation and antimigration effects on human A549 lung cancer cells. To search its target‐related proteins, protein expression profiles of BF‐treated and control cells were compared using two quantitative proteomic methods, iTRAQ‐based and label‐free proteomic analysis. A total of 5428 proteins were identified in iTRAQ‐based analysis while 6632 proteins were identified in label‐free analysis. The number of common identified proteins of both methods was 4799 proteins. By application of 1.20‐fold for upregulated and 0.83‐fold for downregulated cutoff values, 273 and 802 differentially expressed proteins were found in iTRAQ‐based and label‐free analysis, respectively. The number of common differentially expressed proteins of both methods was 45 proteins. Results of bioinformational analysis using Metacore^TM showed that the two proteomic methods were complementary and both suggested the involvement of oxidative stress and regulation of gene expression in the effects of BF, and fibronectin‐related pathway was suggested to be an important pathway affected by BF. Western blotting assay results confirmed BF‐induced change in levels of fibronectin and other related proteins. Overexpression of fibronectin by plasmid transfection ameliorated antimigration effects of BF. Results of the present study provided information about possible target‐related proteins and signal network of BF.     

Effect of propionic acid on citric acid fermentation in an integrated citric acid–methane fermentation process

In this study, an integrated citric acid-methane fermentation process was established to solve the problem of wastewater treatment in citric acid production. Citric acid wastewater was treated through anaerobic digestion and then the anaerobic digestion effluent (ADE) was further treated and recycled for the next batch citric acid fermentation. This process could eliminate wastewater discharge and reduce water resource consumption. Propionic acid was found in the ADE and its concentration continually increased in recycling. Effect of propionic acid on citric acid fermentation was investigated, and results indicated that influence of propionic acid on citric acid fermentation was contributed to the undissociated form. Citric acid fermentation was inhibited when the concentration of propionic acid was above 2, 4, and 6 mM in initial pH 4.0, 4.5 and, 5.0, respectively. However, low concentration of propionic acid could promote isomaltase activity which converted more isomaltose to available sugar, thereby increasing citric acid production. High concentration of propionic acid could influence the vitality of cell and prolong the lag phase, causing large amount of glucose still remaining in medium at the end of fermentation and decreasing citric acid production.     

Improved extracellular expression and high-cell-density fed-batch fermentation of chitosanase from <Emphasis Type="Italic">Aspergillus Fumigatus</Emphasis> in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Chitosanase (CSN) from Aspergillus fumigatus has good thermal stability, wide pH range duration, and effective hydrolysis for chitosan. Inhere, CSN was successfully expressed in Escherichia coli followed by extracellular secretion under the guidance of an N-terminal signal peptide PelB, which effectively prompted its secretion out of E. coli cells. To facilitate its later purification, N-terminal or C-terminal 6xHis epitope tag was added to the PelB-CSN protein complex. Our results indicated that PelB-CSN without 6xHis-tag (PelB-CSN) or with N-terminal 6xHis-tag (PelB-CSN-N) can both be effectively secreted into the medium, while CSN with 6xHis-tag anchored at C-terminus was expressed as inclusion bodies. Process optimization strategies were further developed to improve the secretion efficiency of recombinant PelB-CSN-N in E. coli. Under the induction of 10 g/L lactose in shake-flask culture, the extracellular activity of CSN reached 6015 U/mL at 25 °C in TB medium containing 1 % glycine. Moreover, a fed-batch fermentation strategy for high-cell-density cultivation was applied in a 5-L fermenter, increasing the extracellular CSN activity to 14,000 U/mL in 2-day fermentation with the optimal addition of lactose and glycine.