自由基与软骨基质胶原蛋白类型改变

本文利用ＳＤＳ－聚丙烯酰胺凝胶电泳方法,定量研究了体外培养的软骨细胞和软骨组织基质中Ⅱ型胶原蛋白的含量。结果表明氧自由基（·Ｏ－２和·ＯＨ）和具有自由基性质的物质（黄腐酸,镰刀菌毒素）可使软骨细胞合成,分泌异常的非Ⅱ型的胶原蛋白,同时,硒化合物可明显地抑制此种效应。     

Identification and characterization of glucocorticoid receptors in liver of nude mice

Glucocorticoids regulate the expression of many liver-specific genes via glucocorticoid receptors. The presence of glucocorticoid receptors in liver has been reported in many mammalian species but not in nude mice. In the present study, we demonstrate the presence of specific glucocorticoid receptors in nude mouse liver. The binding of ligands to these receptors could be completely inhibited by RU486, and partially blocked by hydrocortisone and progesterone, whereas estrogen and testosterone had no effect. Hydrocortisone down-regulated the level of glucocorticoid receptors in livers of nude mice and correspondingly enhanced the activities of tyrosine aminotransferase and -glutamyltransferase. Our results indicate that glucocorticoid receptors in nude mouse liver are specific, fully functional, and present at levels 28.5-fold higher than in the liver of normal inbred mice. We suggest that the nude mouse is a valuable model for studies of hepatic glucocorticoid action and may provide a clue to a putative hepatic-thymic interaction.     

嗜盐耐盐微生物抗盐胁迫相关离子转运蛋白研究进展

离子转运蛋白在维持细胞内pH稳态、离子动态平衡等方面发挥着重要作用。钠离子转运体和钾离子转运体在嗜盐耐盐微生物中广泛存在,其"保钾排钠"机制是微生物抗盐胁迫的两大策略之一。近年来,嗜盐耐盐微生物中许多新型钠、钾离子转运体被陆续发现,如RDD蛋白、UPF0118蛋白、DUF蛋白和KimA蛋白等;Fe³⁺、Mg²⁺等其他金属离子的转运蛋白也被证实可通过影响微生物胞内相容性溶质的合成起到渗透调节的作用。本文综述了嗜盐耐盐微生物中抗盐胁迫相关的各类离子转运蛋白,分析其分子结构和工作机理,并对这些蛋白在农业方面的应用进行了展望。继续发现新的离子转运蛋白,探究抗盐胁迫相关离子转运蛋白的结构和机理,解析各转运系统的协同作用及分子调控机制,将进一步加深对嗜盐耐盐微生物抗盐胁迫调控的认识,并为盐碱地农作物的改良等提供新的思路。     

Sequences within the last intron function in RNA 3''-end formation in cultured cells.

In cultured cells, little if any mRNA accumulates from an intronless version of the human gene for triosephosphate isomerase (TPI), a gene that normally contains six introns. By deleting introns either individually or in combinations, it was demonstrated by Northern (RNA) blot hybridization that while the deletion of a greater number of introns generally results in a lower level of product mRNA, not all introns contribute equally to mRNA formation. For example, intron 1 appeared to be dispensable, at least when the remaining introns are present, but deletion of the last intron, intron 6, reduced the level of product mRNA to 51% of normal. To determine how intron 6 contributes to mRNA formation, partial deletions of intron 6 were constructed and analyzed. Deletion of the lariat and acceptor splice sites or the donor, lariat, and acceptor splice sites, each of which precluded removal of the intron 6 sequences that remained, reduced the level of product mRNA to < 1 or 27% of normal, respectively. As measured by RNase mapping and cDNA sequencing, the decrease in mRNA abundance that was attributable to the complete and partial intron 6 deletions was accompanied by an increase in the abundance of pre-mRNA that lacked a mature 3' end, i.e., that was neither cleaved nor polyadenylated. We infer from these and other data that sequences within the final intron facilitate proper 3'-end formation, possibly through an association with the components of a productive spliceosome.     

Monovalent cation effects on intermolecular purine-purine-pyrimidine triple-helix formation.

The binding of a 19-mer guanosine-rich oligodeoxyribonucleotide, TG3TG4TG4TG3T (ODN 1), to a complementary polypurine DNA target was investigated by DNase I footprinting and restriction endonuclease protection assays. Monovalent cations inhibited intermolecular purine-purine-pyrimidine triple-helical DNA formation, with K+ and Rb+ being most effective, followed by NH4+ and Na+. Li+ and Cs+ had little to no effect. Similar results were observed with the G/A-rich oligonucleotide AG3AG4AG4AG3AGCT. Kinetic studies indicated that monovalent cations interfered with oligonucleotide-duplex DNA association but did not significantly promote triplex dissociation. The observed order of monovalent cation inhibition of triplex formation is reminiscent of their effect on tetraplex formation with G/T-rich oligonucleotides. However, using electrophoretic mobility shift assays we found that the oligonucleotide ODN 1 did not appear to form a four-stranded species under conditions promoting tetraplex formation. Taken together, our data suggest that processes other than the self-association of oligonucleotides into tetraplexes might be involved in the inhibitory effect of monovalent cations on purine-pyrimidine-purine triplex formation.     

卡介苗对枯否细胞生物特性影响的免疫细胞化学研究

卡介苗(BCG)是增强肝枯否细胞(KC)抗肝癌细胞作用的最佳免疫制剂之一。本实验是给大鼠BCG后,应用溶菌酶免疫细胞化学法显示KC,以图象分析系统测定KC的数量、分布和面积,以细胞分光光度计测定KC溶菌酶活性;分离KC体外受BCG作用后,用ELISA法测定RC的Fc受体表达。结果显示:BCG使KC数量增多一倍,尤以肝小叶周边带为显著;KC体积明显增大,细胞面积增大55.71％,周边带KC面积增大一倍上;细胞溶菌酶光密度增大64.35％;Fc受体表达增强64.82％。上述结果是BCG增强KC抗肝癌细胞作用有关细胞学机制。     

25000年以来渤海湾西岸古环境探讨

 本文依据孢粉、微体古生物、放射性碳测年、因子分析等资料,表明25000a,BP 以来渤海湾西岸的古植被,古地理环境演变既受气候冷暖变化的影响,又受海平面变化的制约。25000—23000a,BP 为高海平面时期,古植被为森林草甸植被,23000—12000a,BP,气候冷干,为低海平面时期,以草原植被为主,前期和后期为沼泽草甸植被。12000—5000a,BP 气候温凉或温暖湿润为海平面上升时期,为阔叶林草甸或沼泽草甸植被,5000a,BP 以来,气候变凉变干,为海退时期,古植被由沼泽草甸演变为盐生草甸。     

Inferring cultural reproduction from lithic data: A critical review

The cultural reproduction of lithic technology, long an implicit assumption of archaeological theories, has garnered increasing attention over the past decades. Major debates ranging from the origins of the human culture capacity to the interpretation of spatiotemporal patterning now make explicit reference to social learning mechanisms and cultural evolutionary dynamics. This burgeoning literature has produced important insights and methodological innovations. However, this rapid growth has sometimes led to confusion and controversy due to an under-examination of underlying theoretical and methodological assumptions. The time is thus ripe for a critical assessment of progress in the study of the cultural reproduction of lithic technology. Here we review recent work addressing the evolutionary origins of human culture and the meaning of artifact variation at both intrasite and intersite levels. We propose that further progress will require a more extended and context-specific evolutionary approach to address the complexity of real-world cultural reproduction.     

酿酒酵母INO80染色质重塑复合物调控基因表达的研究进展

表观遗传调控是真核生物基因表达精细调控的重要组成部分,主要包括DNA甲基化、组蛋白修饰和染色质重塑。其中,染色质重塑因子可影响组蛋白修饰酶和转录因子与特定位点的结合,在基因表达调控中占有重要地位。INO80复合物是进化上保守的染色质重塑复合物,能利用ATP水解获得的能量促进核小体的滑动和驱逐。INO80复合物除了在DNA复制、修复中发挥重要功能外,还通过改变DNA可及性调控酿酒酵母的基因表达。本文综述了染色质重塑复合物的分类及组成,重点介绍了酿酒酵母多亚基复合物INO80在基因表达调控中的重要功能,包括驱逐RNA聚合酶Ⅱ、响应信号转导途径和改变基因表达水平等,并着重总结了其在酿酒酵母环境胁迫响应机理中的研究进展。深入研究INO80染色质重塑复合物的功能,可为理解真核生物精细代谢调控的机制,并进一步开发基于染色质重塑等表观调控水平的微生物代谢工程和合成生物学改造策略,提高菌株的环境胁迫耐受性和发酵性能提供基础。