THE RADIATION STABILITY OF PERFLUOROALKOXY RESIN

By examining the changes in melting temperature, heat of fusion, tensile strength and ultimate elongation at 150-degrees-C, and weight loss, radiation effects on perfluoroalkoxy resins (PFA) were investigated. The results show that at the temperatures used here the predominant effect caused by radiation on PFA is degradation of the molecular weight. The radiation stability is much better than that of polytetrafluoroethylene, however.

PHASE-BEHAVIOR IN EPOXY-RESIN CONTAINING PHENOLPHTHALEIN POLY(ETHER ETHER SULFONE)

Phenolphthalein poly(ether ether sulphone) (PES-C) was found to be miscible with uncured bisphenol-A-type epoxy resin, i.e. diglycidyl ether of bisphenol A (DGEBA), as shown by the existence of a single glass transition temperature within the whole composition range. Miscibility between PES-C and DGEBA is considered to be due mainly to the entropy contribution. However, dynamic mechanical analysis (d.m.a.) and scanning electron microscopy (SEM) studies revealed that PES-C exhibits different miscibility with four cured epoxy resins (ER). The overall compatibility and the resulting morphology of the cured blends are dependent on the choice of cure agent. For the blends cured with amines (4,4'-diaminodiphenylmethane (DDM) and 4,4'-diaminodiphenylsulphone (DDS)), no phase separation occurs as indicated by either d.m.a. or SEM. However, for the blends cured with anhydrides (maleic anhydride (MA) and phthalic anhydride (PA)), both d.m.a. and SEM clearly show evidence of phase separation. SEM study shows that the two phases interact well in the MA-cured blend while the interface between the phases in the PA-cured blend is poorly bonded. The differences in the overall compatibility and the resulting morphology between the amine-cured and anhydride-cured systems have been discussed from the points of view of both thermodynamics and kinetics.

Expression, purification of recombinant flounder MRF4 protein in Escherichia coli and analysis of its polyclonal antibodies

MRF4 is one of muscle regulatory factors and plays critical roles during skeletal muscle development. The muscle development is important for the fish growth which is an important economic factor for the fish culture. To analyze the function of MRF4 in fish, the founder MRF4 antibody was prepared. The flounder MRF4 was cloned, ligated into prokaryotic expression vector pET-30b and expressed in strain E. coli BL21 (130). The recombinant flounder MRF4 fusion protein was soluble and purified with cobalt IMAC resins. To prepare MRF4 polyclonal antibodies, rabbits were immunized with the soluble protein and the increasing level of antibodies was determined by Western blot. Also, the endogenous flounder MRF4 was recognized by the anti-serum. The result further proved the existence of the anti-MRF4 antibody in the anti-serum, which will be useful for studies on the function of flounder MRF4.

牙鲆rag基因的克隆及表达研究

牙鲆在中国北方沿海地区形成了大规模的工厂化养殖，成为我国海水养殖的一大重要产业。然而疾病的频繁发生严重阻碍了这一产业的发展，为了保证牙鲆产业稳定、健康、持续地发展，开展鱼类免疫系统的基础研究，提高鱼类抵抗病原菌侵害的能力，本研究从牙鲆免疫系统的个体发育过程入手，克隆了其rag（recombination activating gene）基因，在此基础上对其组织特异性表达进行了分析。 研究结果表明牙鲆rag1基因由4个外显子和3个内含子组成，第一个外显子位于5’非翻译区，这一外显子存在两种不同的剪切方式。牙鲆rag1基因编码1068个氨基酸。牙鲆rag2基因的编码区序列长为1602 bp，编码533个氨基酸，没有在牙鲆rag2基因编码区内发现内含子的存在。rag基因间序列长为3128 bp，两个基因共用一段3’非编码区。 本试验通过RT-PCR检测发现，牙鲆的rag1和rag2基因在头肾和体肾中均有表达。整装原位杂交结果表明，牙鲆在受精后第8天开始起有rag1和rag2基因的表达，主要在胸鳍前面，腮背部的部位表达，这个区域与后来胸腺出现的位置相一致。冰冻切片结果显示，rag是在靠近咽部的区域有表达。石蜡切片原位杂交结果显示，rag基因在胸腺中的表达显示出不均一性，着色较深的为皮层区，而着色比较浅的为髓部。 将牙鲆rag1基因的一部分（编码559个氨基酸）和rag2全基因序列（编码533个氨基酸）插入到表达质粒pProEXTM HTa上，在大肠杆菌E. coli BL-21中进行体外表达与分析，结合BD TALONTM Metal Affinity Resins亲和柱纯化了RAG2蛋白。