基于Golden Gate技术的齐整小核菌转录单元高效组装系统

【目的】为齐整小核菌代谢工程研究建立高效的转录单元组装系统。【方法】通过应用Golden Gate技术,以mobius assembly为基础,分别设计并构建DNA元件标准化接口改造、单转录单元组装、应用质粒(多转录单元)组装等功能的载体,从而形成一套完整的多转录单元组装系统。【结果】构建了2个用于DNA元件标准化接口改造的Level 0载体,4个用于单转录单元组装的Level 1载体,4个用于应用质粒组装的Level 2载体和13个应用质粒组装的辅助质粒。然后应用此系统为齐整小核菌组装了若干经过标准化接口改造的DNA元件质粒、单转录单元质粒和硬葡聚糖相关基因的功能分析质粒。所构建的最终应用质粒可以同时适用于齐整小核菌的根癌农杆菌介导转化法、电穿孔转化法和原生质体转化法。【结论】此质粒系统具有强大的DNA设计、组装和容纳能力,为未来齐整小核菌代谢工程和功能基因组学研究提供了高效的质粒构建技术平台。     

Establishment of a novel dwarf rat strain: cartilage calcification insufficient (CCI) rats

Rats with dwarfism accompanied by skeletal abnormalities, such as shortness of the limbs, tail, and body (dwarf rats), emerged in a Jcl-derived Sprague-Dawley rat colony maintained at the Institute for Animal Experimentation, St. Marianna University Graduate School of Medicine. Since the dwarfism was assumed to be due to a genetic mutation based on its frequency, we bred the dwarf rats and investigated their characteristics in order to identify the causative factors of their phenotypes and whether they could be used as a human disease model. One male and female that produced dwarf progeny were selected, and reproduction was initiated by mating the pair. The incidence of dwarfism was 25.8% among the resultant litter, and dwarfism occurred in both genders, suggesting that it was inherited in an autosomal recessive manner. At 12 weeks of age, the body weights of the male and female dwarf rats were 40% and 57% of those of the normal rats, respectively. In soft X-ray radiographic and histological examinations, shortening and hypoplasia of the long bones, such as the tibia and femur, were observed, which were suggestive of endochondral ossification abnormalities. An immunohistochemical examination detected an aggrecan synthesis disorder, which might have led to delayed calcification and increased growth plate thickening in the dwarf rats. We hypothesized that the principal characteristics of the dwarf rats were systemically induced by insufficient cartilage calcification in their long bones; thus, we named them cartilage calcification insufficient (CCI) rats.     

牛肝TrnaIle的序列分析和二级结构

用随机降解法和Donis-Keller酶分析法,测定了牛肝tRNA^Ile序列.牛肝tRNA^Ile长77个碱基;G5·G69不配对为其显著特征.依据tRNA螺旋区和环区自由能大小及Holley模型,确定了tRNA^Ile的二级结构.     

Induction of tolerance to oxidative stress in the green alga, Chlamydomonas reinhardtii, by abscisic acid

The effect of abscisic acid (ABA) on the tolerance to oxidative stress in a freshwater green alga, Chlamydomonas reinhardtii, was investigated. Exogenously added ABA enhanced the growth of this alga, which was observed under continuous illumination but not in the dark. The cells treated with ABA for 24 h showed tolerance to oxidative stress caused by exposure to paraquat or hydrogen peroxide. In the ABA‐treated cells, the activities of two antioxidant enzymes, catalase (CAT) and ascorbate peroxidase (APX), were significantly higher than those in the untreated control. The result suggests that ABA plays a role in the enhancement of tolerance to oxidative stress by increasing the activity of antioxidant enzymes.