广西民族大学2014年硕士研究生入学考试初试自命题科目试题：分子生物学

广西民族大学2014年硕士研究生入学考试初试自命题科目试题：分子生物学；试卷代号：A；适用学科专业：生物化学与分子生物

2000-2013年间我国华南部分省区IBDV流行株的基因分型

引言鸡传染性法氏囊病（Infectious Bursal Disease,IBD）是由鸡传染性法氏囊病病毒（Infectious Bursal Disease Virus,IBDV）引起雏鸡的急性、高度接触性、溶淋巴细胞性的传染病。IBD仍然是目前危害养鸡业的重要病毒性疾病[1]。从IBDV基因组双链的分子变化对流行的IBDV进行分析、分型,将有助于我们全面掌握病毒的分子进化规律,指

四株不同基因型IBDV分离株对三黄鸡的致病性研究

鸡传染性法氏囊病(Infectious Bursal Disease,IBD)是由传染性法氏囊病病毒(Infectious Bursal Disease Virus,IBDV)引起幼鸡的急性、高度接触传染性、杀淋巴细胞性的疾病。不同基因型临床分离株对本地商品鸡的致病性等生物学特性研究将有助于我们厘清基因变化与流行株重要生物学特性之间的关系,为IBD新疫苗研制提供依据。本研究将4个具有不同V

四株不同基因型IBDV分离株对本地三黄鸡的致病性研究

引言鸡传染性法氏囊病(Infectious Bursal Disease,IBD)是由传染性法氏囊病病毒(Infectious Bursal Disease Virus,IBDV)引起幼鸡的急性、高度接触传染性、杀淋巴细胞性的疾病。目前,该病在临床上的一个最大特点是免疫鸡群仍然发病。不同基因型现场分离株对本地商品鸡的致病性等生物学特性研究将有助于我们厘清基因变化与流行株重要生物学特性之间的

Isolation and identification of Bacillus cereus producing cellulase and enzymatic properties analysis

【目的】筛选高效分泌纤维素酶的细菌,为纤维素资源利用提供理论依据。【方法】以羧甲基纤维素钠(CMC-Na)为唯一碳源,对通过筛选培养基从森林湿泥样品中分离筛选出的细菌,采用刚果红染色、革兰氏染色和生化特性及16SrDNA进行鉴定,并对菌株产酶性质进行初步研究。【结果】获得一株纤维素酶产生菌L-30,该菌株在pH4.8、50℃条件下的酶活力为4.25 U/mL,经鉴定L-30为蜡样芽孢杆菌。酶学性质研究表明,L-30菌株所产纤维素酶最适反应pH为6.0,最适温度为50℃,该条件下酶活力最高,达4.95 U/mL,该酶对CMC-Na具有较强的分解能力;L-30菌株在最佳生长条件下,于接种后48 h即可达到产酶高峰,L-30菌株的产纤维素酶能力能稳定遗传。【结论】分离到的L-30为一株高产纤维素酶蜡样芽孢杆菌,其酶学性质好,具有进一步开发利用的价值。[Objective]Cellulase, efficiently producing bacteria, was screened to provide references for cellulose application.[Method]Bacteria was screened by using CMC-Na as the only carbon source from humid soil sample. The methods of Congo red staining, gram staining, biochemical character and molecular property of 16S rDNA were used to identify the bacteria, and the enzymatic properties of the cellulose were also observed. [Result]One strain of cellulase producing bacteria （L-30） was isolated from the humid soil sample. The cellulase activity was 4.25 U/mL in the conditions of pH 4.8 and 50℃. L-30 was identified as Bacillus cereus. The preliminary study on enzymatic properties showed that under the optimum conditions of pH of 6.0 and temperature of 50℃, the cellulose activity reached 4.95 U/mL in this reaction system. The cellulase showed high ability to degrade CMC-Na. L-30 reached its largest amount of the enzyme after cultured for 48 hours and displayed genetic stability on secreting enzyme. [Conclusion]The isolated Bacillus cereus of L-30 with good enzymatic properties should be further developed and utilized.广西林产化学与工程协同创新高水平研究项目(2013B01)； 广西自然科学基金项目(2012GXNSFAA053060)； 广西高校科学技术研究项目(2013YB069

A study on the Construction of a Marine Ecosystem Model Lab Based on Practical Teaching in Marine Ecology

为进一步开展海洋生态学实践教学,设计规划了以仿真模型为基础的海洋生态系统模型馆。该模型馆利用仿真模型将六大海洋生态系统进行室内还原,实现了海洋生态实践教学尤其是野外调查模拟实践活动的可持续开展。文章叙述了模型馆的设计理念和方案,讨论了基于仿真模型的实践教学方式及其实际意义。实践表明,以模型辅助教学的教学模式由于其价格低廉、重复使用性强等特性而易于推广,对自然科学的实践教学、理论教学以及科普宣传工作均起到了借鉴作用。In order to carry out the practical teaching of marine ecology,a marine ecosystem model lab based on the simulation model is designed.In this lab,six major marine ecosystems are reproduced indoors by using the simulation model,and it makes the continuous development of marine ecological practical teaching to be possible,especially,in the field survey.This paper described the design concept and design scheme of this model lab,and discussed the practical teaching mode based on the simulation model and its practical significance.We believe that the model-teaching mode will be easy to popularize because of its low cost and repeated usage,and it will be hopeful to serve as a reference for the practical teaching,theoretical teaching of natural and popular science propaganda.广西民族大学校级科研项目(2016MDYB027

Effect of droplet impact on molten pool dynamics in hybrid laser-MIG welding of aluminum alloy

In order to investigate the effect of droplet impact on molten pool dynamics in hybrid laser-MIG (metal inert gas) welding, a three-dimensional mathematical model was developed, and a new approach to simulate the droplet impact was proposed. In the model, the droplet heat and impact under the influence of laser was considered, and the deformation of molten pool was calculated with considering droplet impact and arc pressure. To simplify the model, a modified body heat source model was presented for laser source to take into account multiple reflections and Fresnel absorption. Surface tension, electromagnetic force, and buoyancy were considered to calculate the fluid flow pattern. Furthermore, several dimensionless numbers were used to recognize the importance of the driving forces in molten pool. It was found that molten pool dynamics and final weld bead geometry were strongly affected by the droplet impact. To demonstrate the importance of droplet impact, the temperature, velocity distribution, and the deformation of molten pool were analyzed and compared under different conditions. With considering droplet impact, the penetration was bigger, and the width was smaller. Furthermore, the simulated weld bead geometry was in good agreement with experimental measurement

Amplification and Sequence Analysis of VP1 Gene Fragment of Local Epidemic IBDV Isolates

为了解鸡传染性法氏囊病病毒(IBDV)地方流行毒株在基因组B节段关键序列上的分子进化情况,通过反转录PCR(RT-PCR)技术对6个IBDV不同地方分离株的VP1基因中与病毒致病型相关的一个片段(1 518bp~1 997bp,共480bp)进行扩增,并对所获得的VP1 480bp片段进行核苷酸的序列测定,与IBDV参考株和常用疫苗株的相应序列进行比较分析和绘制遗传进化树。结果表明,6个分离株与参考株在VP1RNA聚合酶基序Ⅵ和基序Ⅶ上均保守,在特征性氨基酸位点上,3个广西分离株QX0604、WZ0704和NN0603与参考的vvIBDV相同,而分离株BH111(广西)、JS17(江苏)和HUN0804(湖南)则既具有vvIBDV的位点特征,又具有经典毒株特征,但不同毒株在不同位点上表现不同;在同源性分析上,JS17、BH111、QX0604、WZ0704和NN0603等5个毒株与参考用vvIBDV毒株的同源性较高,在核苷酸和氨基酸水平上分别为92.5%~100.0%和97.5%~100.0%,但与2个常用疫苗株和经典毒株的同源性仅分别为87.9%~90.0%和96.2%~96.9%,分离株HUN0804则与经典毒株和2个疫苗株更接近;在遗传进化树上,JS17和BH111等5个分离株与vvIBDV在一个分支上,亲缘关系更近,而HUN0804则与经典毒株和2个疫苗株在另一个大分支。表明不同分离株在VP1的功能基序上保持保守,但分离株在特征性氨基酸位点上则发生了变化,大多数分离株与常用疫苗株之间的同源性较低,亲缘关系较远。In order to look insight into the molecular evolution in B segment of different local epidemic infectious bursal disease virus（IBDV）isolates,the present study was carried out by amplification and sequencing of a fragment with 480bp（which is related to pathotype of IBDV）located in VP1gene（1 518bp-1 997bp）of IBDV by RT-PCR.The sequences of the epidemic IBDV isolates were compared with reference IBDV and commonly used vaccine strains,and the phylogenetic tree was established.The results showed that the motifⅥ and motifⅦ located in the VP1 480 bp region were highly conserved between the 6local epidemic IBDV isolates and reference IBDVs.The characteristic amino acid residues of isolates QX0604,WZ0704 and NN0603were conserved to vvIBDV,however,the other 3isolates showed mixed characteristic amino acid residues,some residues were conserved to vvIBDV,and some were conserved to classical IBDV.On the other hand,the five field isolates QX0604,WZ0704,NN0603,JS17 and BH111showed high homology to vvIBDV,with 92.5%-100.0% and 97.5%-100.0%in nucleotide and amino acid levels,respectively.They showed lower homology to the 2commonly used vaccine strains and reference classical IBDVs（87.9%-90.0%in nucleotide level,96.2%-96.9%in amino acid level）.HUN0804 showed high homology to the 2commonly used vaccine strains and reference classical IBDVs.In the phylogenetic tree,the five isolates were grouped with vvIBDV strain,HUN0804 grouped with vaccine strains and reference classical IBDVs.These results suggested that local epidemic IBDVs were conserved in the functional motif of VP1,however,some of the characteristic amino acid residues were changed and most of the isolates showed low homology and genetic relationship to commonly used vaccine strains.广西自然科学基金项目(2014GXNSFDA118018)； 广西高校科学技术研究项目(2013YB069,200809LX255)； 南宁市科技攻关项目(20142079