Study on Cellulase Gene Expressed in Pichia pastoris and Analyses of Its Biochemical Characters

Objectives: In order to increase cellulose degradation, cellulase was expressed in this study. Literature Review: Cellulose is the most abundant organic carbon source on Earth;its enzymatic hydrolysis will be very useful for bioenergy production and resource recycling. Methods: Cellobiohydrlase I (CBH I) gene was amplified from genomic DNA of Trichoderma koningii and inserted into pGAPZα A plasmid to construct the vector of pGAPZαA-CBH I. It was linearized and transformed into Pichia pastoris by electroporation. The recombinant Pichia pastoris was selected and incubated with YPD medium for cellulase secretion. Results: The result showed that CMCase and avicelase activity in the supernatant was 1.1798 U/mL and 0.1276 U/mL, the molecular weight of the expressed protein was 53 kDa determined with SDS-PAGE analyses, and the optimal temperature and pH of the expressed cellulase were 45?C - 50?C and 4.5 - 5.0, respectively. Conclusion: Cellulase gene from T. koningii has been successfully cloned and expressed in Pichia pastoris.

成人门静脉海绵样变治疗效果分析

目的探讨成人门静脉海绵样变的治疗方法及效果。方法回顾性分析2011年4月至2021年4月在郑州大学第一附属医院就诊并且随访资料完整并接受侵入性治疗的65例成人门静脉海绵样变患者的临床资料,根据患者治疗方法的不同将其分为经颈静脉肝内门腔静脉分流术(TIPS)组24例,脾-肺固定组11例,脾切除断流组22例,套扎组8例,采用Kaplan-Meier生存曲线和Log-rank检验比较4组患者肝性脑病发生时间和再出血时间的差异。结果4组患者的性别、年龄、术前血清AST、血清总胆红素、血清白蛋白及肝功能分级差异均无统计学意义(均P>0.05)。TIPS组术后半年、1、3年肝性脑病的发生率分别为33.3%±9.6%、46.5%±10.3%、64.4%±13.1%,肝性脑病的发生时间与其他3组比较差异具有统计学意义(χ^(2)=31.191,P=0.000)。TIPS组有3例患者在术后半年内出现上消化道出血,与脾-肺固定组再出血发生时间相比差异具有统计学意义(χ^(2)=7.542,P=0.006)。结论治疗门静脉海绵样变方法较多,应根据患者的病因、临床症状及梗阻部位选择个体化的治疗方案。