Attenuated Secretion of the Thermostable Xylanase xynB from Pichia pastoris Using Synthesized Sequences Optimized from the Preferred Codon Usage in Yeast

( Huang Yuan Kai ),( Yao Sheng Chen ),( De Lin Mo ),( Pei Qing Cong ),( Zu Yong He ) 한국미생물 · 생명공학회 2012 Journal of microbiology and biotechnology Vol.22 No.3

Xylanase has been used extensively in the industrial and agricultural fields. However, the low-yield production of xylanase from native species cannot meet the increasing demand of the market. Therefore, improving the heterologous expression of xylanase through basic gene optimization may help to overcome the shortage. In this study, we synthesized a high-GC-content native sequence of the thermostable xylanase gene xynB from Streptomyces olivaceoviridis A1 and, also designed a slightly AT-biased sequence with codons completely optimized to be favorable to Pichia pastoris. The comparison of the sequences` expression efficiencies in P. pastoris X33 was determined through the detection of single-copy-number integrants, which were quantified using qPCR. Surprisingly, the high GC content did not appear to be detrimental to the heterologous expression of xynB in yeast, whereas the optimized sequence, with its extremely skewed codon usage, exhibited more abundant accumulation of synthesized recombinant proteins in the yeast cell, but an approximately 30% reduction of the secretion level, deduced from the enzymatic activity assay. In this study, we developed a more accurate method for comparing the expression levels of individual yeast transformants. Moreover, our results provide a practical example for further investigation of what constitutes a rational design strategy for a heterologously expressed and secreted protein.

Dynamic and Damage Characteristics of Mortar Composite under Impact Load

Qing Li,Tong-de Zhao,Chen Huang,Bing-bing Yu,Zheng-Hua Gao,Kai Wang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.3

In the process of underground construction, it is common to spray concrete on the working surface, which will form a concrete-rock composite structure, to achieve the expected reinforcement effect. Compared with pure concrete or rock structures, composite structures have different mechanical properties, energy evolution and damage characteristics. Understanding the dynamic mechanics and damage characteristics of composite structures under impact loads is important to the safety of underground engineering construction. First, dynamic compression tests on different grades of mortar-sandstone composite specimens were carried out by using a Hopkinson pressure bar system to discuss the effect of impact velocities on the mechanical properties and failure modes of composite specimens. The results show that the dynamic peak stress, strain energy density and fragmentation block of the mortar-sandstone composite have an obvious strain rate effect. With an increase in impact velocity, the internal cracks of the sample do not have sufficient time to expand, and the energy absorbed by the sample leads to the continuous initiation of new cracks in the sample, resulting in an increasing damage degree of composite specimens. The increase in mortar strength can significantly increase the peak stress, improve the load-bearing capacity of the sample, and reduce the degree of sample damage. At the same impact velocity, the fragmentation degree of the mortar sample is more severe than that of sandstone, and the mortar sample is broken into powder debris, while the sandstone is broken into fragments. In addition, according to the failure properties of the composite sample, the mortar and sandstone samples are described by different damage models, and the dynamic damage constitutive model of the mortar-sandstone composite is established based on the overlay principle. The dynamic test results were fitted. The research shows that the fitting curves of the model are well fitted with the test curves and that the model accurately reflects the changes in the mechanical parameters of the composite specimens.

Prognostic Values of Various Clinical Factors and Genetic Subtypes for Diffuse Large B-cell lymphoma Patients: A Retrospective Analysis of 227 Cases

Zhou, De,Xie, Wan-Zhuo,Hu, Ke-Yue,Huang, Wei-Jia,Wei, Guo-Qing,He, Jing-Song,Shi, Ji-Min,Luo, Yi,Li, Li,Zhu, Jing-Jing,Zhang, Jie,Lin, Mao-Fang,Ye, Xiu-Jin,Cai, Zhen,Huang, He Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.2

Aim: To analyze the significance of different clinical factors for prognostic prediction in diffuse large B-cell lymphoma (DLBCL) patients. Methods: Two hundred and twenty-seven DLBCL patients were retrospectively reviewed. Patients were managed with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) regimen or rituximab plus the CHOP (RCHOP) regimen. Results: Lactate dehydrogenase (LDH), ${\beta}2$-microglobulin (${\beta}2$-M), B symptoms, Ann Arbor stage and genetic subtypes were statistically relevant in predicting the prognosis of the overall survival (OS). In the CHOP group, the OS in patients with germinal center B-cell-like (GCB)(76.2%) was significantly higher than that of the non-GCB group (51.9%, P=0.032). With RCHOP management, there was no statistical difference in OS between the GCB (88.4%) and non-GCB groups (81.9%, P=0.288). Conclusion: Elevated LDH and ${\beta}2$-M levels, positive B symptoms, Ann Arbor stage III/IV, and primary nodal lymphoma indicate an unfavorable prognosis of DLBCL patients. Patients with GCB-like DLBCL have a better prognosis than those with non-GCB when treated with the CHOP regimen. The RCHOP treatment with the addition of rituximab can improve the prognosis of patients with DLBCL.

Analysis of Volatile Compounds in Chinese Soy Sauces Moromi Cultured by Different Fermentation Processes

Jia Zheng,Chong-De Wu,Jun Huang,Rong-Qing Zhou,Xue Pin Liao 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.3

The volatile compounds in Chinese soy sauce moromi cultured by different fermentation processes [lowsalt solid-state fermentation (LSSF), high-salt dilute-state fermentation (HSDF), and high-salt constant temperature fermentation (HSCT)] were determined by GC-MS. The LSSF moromi had the highest total concentration of volatile compounds, followed by HSCT and HSDF moromi. Volatiles such as ethyl linoleate and ethyl oleate dominated in HSCT moromi. 2,3-Butanediol and 2,6-dimethylpyrazine were present at high content in LSSF moromi. The hierarchal cluster analysis (HCA) and principal component analysis (PCA) were employed to investigate the fermentation process effect on the category of samples. Based on HCA,HSCT (a1 and a2) and HSDF (b1 and b2) clustered in 1group, and LSSF (c1 and c2) located in another group. PCA illustrated that each kind of samples correlating with specific volatile compound groups were clearly differentiated according to their fermentation processes. The results suggest that GC-MS together with multivariate analyses could provide practical reference to recognize different Chinese soy sauces moromi.

Disturbance-observer-based Neural Sliding Mode Repetitive Learning Control of Hydraulic Rehabilitation Exoskeleton Knee Joint with Input Saturation

Yong Yang,Xiu-Cheng Dong,Zu-Quan Wu,Xia Liu,De-Qing Huang 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.12

Rehabilitation exoskeleton is a wearable robot for recovery training of stroke patients. It is a complex human-robot interaction system with highly nonlinearities, such as modeling uncertainties, unknown human-robot interactive force, input constraints, and external disturbances. This paper focuses on trajectory tracking control of a rehabilitation exoskeleton knee joint which is driven by a hydraulic actuator with input saturation. A radial basis function neural network (RBF-NN) sliding mode repetitive learning control strategy is presented for the exoskeleton knee joint, where the RBF-NN is combined with a sliding mode surface to compensate for the modeling uncertainties and the controller difference as well as enhanced the robustness of the system. Incorporating with a nonlinear observer, a repetitive learning scheme is constructed to estimate the unknown external disturbances and learn the periodic human-robot interactive force caused by repetitive recovery training. Utilizing the Lyapunov approach, the stability of the closed-loop control system and the observer are guaranteed. Comparative simulation results verify the effectiveness of the proposed control scheme.