Nicotinamide/nicotinic acid mononucleotide adenylyltransferase, new insights into an ancient enzyme

Nicotinamide/nicotinic acid mononucleotide adenylyltransferase (NMNAT) has long been known as the master enzyme in NAD biosynthesis in living organisms. A burst of investigations on NMNAT, going beyond enzymology, have paralleled increasing discoveries of key roles played by NAD homeostasis in a number or patho-physiological conditions. The availability of in-depth kinetics and structural enzymology analyses carried out on NMNATs from different organisms offer a powerful tool for uncovering fascinating evolutionary relationships. On the other hand, additional functions featuring NMNAT have emerged from investigations aimed at unraveling the molecular mechanisms responsible for complex biological phenomena such as neurodegeneration. NMNAT appears to be a multifunctional protein that sits both at the core of central metabolism and at a crossroads of multiple cellular processes. The resultant wealth of biochemical data has built a robust framework upon which design of NMNAT activators, inhibitors or enzyme variants of potential medical interest can be based.     

RNA结合蛋白与人类男性不育

本文概括了控制精子正常产生的诸多候选基因在染色体上的定位、演化及其编码的 RNA 结合蛋白与人类男性精子发生之间关系研究方面的最新进展,为人类男性不育症的治疗和计划生育的顺利推行奠定了坚实的理论基础并展示出光明的前景。     

DNA in wheat seeds from European archaeological sites

We have used hybridization analysis to detect ancient DNA in wheat seeds collected from three archaeological sites in Europe and the Middle East. One of these samples, carbonizedT. spelta dated to the first millennium BC, has yielded PCR products after amplification with primers directed at the leader regions of the HMW (high molecular weight) glutenin alleles. Sequences obtained from these products suggest that the DNA present in the Danebury seeds is chemically damaged, as expected for ancient DNA, and also indicate that it should be possible to study the genetic variability of archaeological wheat by ancient DNA analysis. Finally, we describe a PCR-based system that enables tetraploid and hexaploid wheats to be distinguished.     

Age-related changes of the pattern of non-histone proteins in active and condensed fractions of mouse liver chromatin and hepatocarcinoma

Summary Electrophoretic analysis of histones and non-histone acid-soluble proteins in active (nuclease sensitive) and inactive chromatin from liver of young and old CBA mice and in age-related hepatocarcinomas showed a higher ratio of NHP: histones in active chromatin in old cells. Some liver- and hepatoma-specific fractions of non-histone proteins have been identified as chromatin matrix proteins.     

利用酵母双杂交系统筛选IrrE相互作用蛋白

本研究通过酵母双杂交技术,构建了IrrE蛋白为诱饵载体,从拟南芥cDNA文库中筛选与IrrE诱饵蛋白相互作用的功能蛋白.研究结果表明,在所获得的阳性克隆中,发现了一个与拟南芥基因At1g01470所编码的蛋白有较高同源性的蛋白,即LEA14蛋白（晚期胚胎发育富集蛋白）,同源性高达98%.推测IrrE转录因子在提高植物耐盐性的过程中起了重要作用.     

Sequence variability of fibrinogen-related proteins (FREPs) in Crassostrea gigas

Fibrinogen-related proteins(FREPs) are lectins with at least a fibrinogen-like domain.They are widespread in Mollusca and play an important role as immune pattern-recognition receptors.These diverse molecules provide interesting models for the study of the evolution of innate immunity.Although oysters are among the most studied mollusks,there have been few investigations of this gene family in oysters.This paper reports the cloning of the first oyster FREP,named CgFREP,from the Pacific oyster Crassostrea gigas.Five types of FREP(CgFREP-1 to CgFREP-5) were obtained based on a single pair of primers,confirming their high diversity.The proteins deduced from these FREPs contained 253-363 amino acids and were divided into three subfamilies based on sequence identities(cutoff point <86%).The topological structure of the phylogenetic tree showed the five CgFREPs clustered together and were completely separated from the subgroup of FREPs obtained from Biomphalaria glabrata(BgFREPs).This implies that FREP diversity evolved before the BgFREPs branched off.An interesting aspect of the CgFREPs was their individual hypermutation.Ninety-three SNPs and five indels were characterized among CgFREPs.Some mutations(e.g.an insertion in CgFREP-5) could cause premature translation termination.Multiple alignments suggest recombination events might have occurred during exchanges between alleles,or by somatic diversification,or both.Individual sequence variability parallels the extraordinary complexity of the innate immune system,suggesting a potential capacity to recognize and eliminate many kinds of pathogens,even in a primitive system.The diversity of immune pattern-recognition receptors may offer an alternative strategy that functions in the absence of highly specific immune globulins,which only emerged in vertebrates.     

环境中有机磷酸酯阻燃剂（TDCP、TECP、TCPP）对人胚肾细胞（HEK293）的影响(英)

水环境中的微污染物有机磷酸酯如三(2-氯乙基)磷酸酯(TCEP)、三(2-氯-异丙基)磷酸酯(TCPP)和三(1,3-二氯丙基)磷酸酯(TDCP)主要用作聚氨酯泡沫塑料的阻燃剂。物理、化学和生物处理很难完全消除这些污染物。本研究的目的是研究阻燃剂在环境水平和较高浓度下对人细胞系的细胞毒性和细胞周期效应。结果表明,在浓度为0.001 mg/L和0.01mg/L时,只有TDCP具有轻微的细胞毒性,而当这三种化学物质浓度100 mg/L以上时对细胞毒性有显著的诱导作用。TCEP和TCPP的EC50分别为276.8 mg/L和58.4mg/L。三种药物均能抑制CDK 4的表达,TDCP能增加CDK 2和cyclin E的表达,而TCEP和TCPP在CDK 2和cyclin E的表达上表现出自差现象。TDCP和TCEP使细胞数量减少,细胞形态发生改变。可见三种化学物质对HEK 293细胞的杀伤作用可能是通过抑制CDK 4调节蛋白而产生的。