一种浓缩噬藻体的反冲超滤技术

噬藻体(Cyanophage)是一类感染蓝藻的病毒,形态上同于噬菌体,近期的研究表明,噬藻体作为水体环境中活跃的动态因子,在控制水体初级生产力和有害藻类水华(Harmful Algal Bloom,HAB)方面可能发挥着重要的作用,甚至影响水体生态系统中食物链的结构,因此研究水体中噬藻体的生理生态学特性对于了解其生态功能是非常重要的,但是由于自然水体中的噬藻体浓度往往较低,难以直接对其进行定性或定量研究,所以对天     

Beta-(1 --> 4)-galactosyltransferase activity in native and engineered insect cells measured with time-resolved europium fluorescence

To evaluate the ability of insect cells to produce complex-type N-glycans, beta-(1 --> 4)-galactosyltransferase (beta4GalT) activity in several insect cell lines was analyzed. For this purpose, we developed a simple and highly sensitive assay for beta-(1 --> 4)-galactosyltransferase (beta4GalT) activity, which is based on time-resolved fluorometry of europium. Bovine serum albumin (BSA) modified with GlcNAc (GlcNAc(44)-BSA) was used as the acceptor. GlcNAc(44)-BSA was coated on a 96-well microplate, and after incubation with the enzyme sample in the presence of UDP-Gal, Eu-labeled RCA(120) (Ricinus communis aggutin I), was added. RCA(120) binds to the Galbeta(1 --> 4)GlcNAc structure in the product, and the bound Eu-RCA(120) was measured by the fluorescence of europium. When bovine beta4Gal-T-I was used as a standard reference enzyme, a linear relationship between enzyme activity and fluorescent signal was obtained over the range of 0-1000 microUnits (IU). Using this system, we were able to measure a low but significant level of beta4GalT activity in Trichoplusia ni cells ('High Five'). In contrast, no endogenous beta4GalT activity was detected in a Spodoptera frugiperda (Sf-9) cell line. However, Sf-9 cells stably transfected with the bovine beta4GalT-I gene and 'High Five' cells infected with a baculovirus containing the same gene produced activity levels that were comparable to or greater than those found in Chinese hamster ovary cells. We also showed that the beta4GalT activity level observed in the baculovirus-infected T. ni cells under the control of immediate early promoter was highly dependent on the post-infection time, suggesting that galactosylation level may also be variable during the infection period.     

Constrained multiple sequence alignment tool development and its application to RNase family alignment

In this paper, we design a heuristic algorithm of computing a constrained multiple sequence alignment (CMSA for short) for guaranteeing that the generated alignment satisfies the user-specified constraints that some particular residues should be aligned together. If the number of residues needed to be aligned together is a constant alpha, then the time-complexity of our CMSA algorithm for aligning K sequences is O(alphaKn(4)), where n is the maximum of the lengths of sequences. In addition, we have built up such a CMSA software system and made several experiments on the RNase sequences, which mainly function in catalyzing the degradation of RNA molecules. The resulting alignments illustrate the practicability of our method.     

美国蓝浆果的引种

１９８８年由美国引入１２个兔眼蓝浆果（ＶａｃｉｎｉｕｍａｓｈｅｉＲｅａｄｅ）品种,在江苏南京和溧水两地试种。１０年来生长结果正常,产量和品质与原产地无显著差异,引种获得成功,证明兔眼蓝浆果能适应本地区自然条件。单株产量平均７．５１ｋｇ,品种间差异显著,最高９．８６ｋｇ,最低１３４ｋｇ。单位投影面积产量３．１０ｋｇ／ｍ２,最高４．０６ｋｇ／ｍ２,最低１．１３ｋｇ／ｍ２。高于或至少不低于原产区产量记录。据此预测,栽植距离适宜时,在本地区亩产量可达１５００～２０００ｋｇ以上。大多数品种果实糖酸比很高,鲜食风味好,氨基酸含量中等,矿质元素Ｚｎ和Ｓｅ含量高。兔眼蓝浆果可在江苏南部丘陵地区发展;此外,还应将试验扩大到南方红黄壤地区;并对本国野生资源开展研究和利用。     

Forwarding Group Multicast Protocol (FGMP) for multihop, mobile wireless networks

In this paper we propose a new multicast protocol for multihop mobile wireless networks. Instead of forming multicast trees, a group of nodes in charge of forwarding multicast packets is designated according to members' requests. Multicast is then carried out via “scoped” flooding over such a set of nodes. The forwarding group is periodically refreshed to handle topology/membership changes. Multicast using forwarding group takes advantage of wireless broadcast transmissions and reduces channel and storage overhead, thus improving the performance and scalability. The key innovation with respect to wired multicast schemes like DVMRP is the use of flags rather than upstream/downstream link state, making the protocol more robust to mobility. The dynamic reconfiguration capability makes this protocol particularly suitable for mobile networks. The performance of the proposed scheme is evaluated via simulation and is compared to that of DVMRP and global flooding. This revised version was published online in August 2006 with corrections to the Cover Date.     

免疫毒素Luffin B-Ng76对人黑色素瘤细胞的体外抑制作用

用ＢｌｕｅＳｅｐｈａｒｏｓｅＣＬ－６Ｂ凝胶亲和层析法从丝瓜籽中分离纯化了单链致核糖体失活蛋白（ｒｉｂｏｓｏｍｅｉｎａｃ－ｔｉｖａｔｉｎｇｐｒｏｔｅｉｎ,ＲＩＰ）——ｌｕｆｉｎＢ。并将ｌｕｆｉｎＢ与抗人黑色素瘤细胞单抗Ｎｇ７６制成了免疫毒素,命名为ｌｕｆｉｎＢ－Ｎｇ７６,它对体外培养的黑色素瘤细胞Ｍ２１有很强的抑制作用,ＩＣ５０为２．５×１０－１１ｍｏｌ／Ｌ,毒性比游离的ｌｕｆｉｎＢ提高４０００倍,而它对非靶的ＨｅＬａ细胞的毒性较Ｍ２１细胞低１２００倍。结果提示ｌｕｆｉｎＢ用于制备免疫毒素具有良好的应用前景。