On the verge of <Emphasis Type="Italic">Umdeutung</Emphasis> in Minnesota: Van Vleck and the correspondence principle. Part one

In October 1924, The Physical Review, a relatively minor journal at the time, published a remarkable two-part paper by John H. Van Vleck, working in virtual isolation at the University of Minnesota. Using Bohr’s correspondence principle and Einstein’s quantum theory of radiation along with advanced techniques from classical mechanics, Van Vleck showed that quantum formulae for emission, absorption, and dispersion of radiation merge with their classical counterparts in the limit of high quantum numbers. For modern readers Van Vleck’s paper is much easier to follow than the famous paper by Kramers and Heisenberg on dispersion theory, which covers similar terrain and is widely credited to have led directly to Heisenberg’s Umdeutung paper. This makes Van Vleck’s paper extremely valuable for the reconstruction of the genesis of matrix mechanics. It also makes it tempting to ask why Van Vleck did not take the next step and develop matrix mechanics himself. This paper was written as part of a joint project in the history of quantum physics of the Max Planck Institut für Wissenschaftsgeschichte and the Fritz-Haber-Institut in Berlin.     

The Response of Debris-Flow Events to Solar Proton Flares （Ⅰ）

By analyzing the observation data from Dongchuan Debris Flow Observation and Research Station and historical data from year 1965 to 1990 gotten from National Astronomical Ob-servatories/Yunnan Observatory,the responding of debris flow in Jiangjia Ravine to Solar Proton Flare is studied. The following conclusion can be drawn. Solar Proton Flare,as one of most im-portant astronomical factors,affects the activity of debris flow in Yunnan. Generally,from 1965 to1990,the more active Solar Pro-ton Flare is,the greater the probability of high frequency and large runoff of debris flow is. On the contrary,the less active Solar Pro-ton Flare is,the greater the probability of low frequency,small runoff,and low sediment transport of debris flow is.     

The neuronal sortilin-related receptor SORL1 is genetically associated with Alzheimer disease

The recycling of the amyloid precursor protein (APP) from the cell surface via the endocytic pathways plays a key role in the generation of amyloid beta peptide (Abeta) in Alzheimer disease. We report here that inherited variants in the SORL1 neuronal sorting receptor are associated with late-onset Alzheimer disease. These variants, which occur in at least two different clusters of intronic sequences within the SORL1 gene (also known as LR11 or SORLA) may regulate tissue-specific expression of SORL1. We also show that SORL1 directs trafficking of APP into recycling pathways and that when SORL1 is underexpressed, APP is sorted into Abeta-generating compartments. These data suggest that inherited or acquired changes in SORL1 expression or function are mechanistically involved in causing Alzheimer disease.     

Improving the thermal stability of lactate oxidase by directed evolution

Lactate oxidase is used in biosensors to measure the concentration of lactate in the blood and other body fluids. Increasing the thermostability of lactate oxidase can significantly prolong the lifetime of these biosensors. We have previously obtained a variant of lactate oxidase from Aerococcus viridans with two mutations (E160G/V198I) that is significantly more thermostable than the wild-type enzyme. Here we have attempted to further improve the thermostability of E160G/V198I lactate oxidase using directed evolution. We made a mutant lactate oxidase gene library by applying error-prone PCR and DNA shuffling, and screened for thermostable mutant lactate oxidase using a plate-based assay. After three rounds of screening we obtained a thermostable mutant lactate oxidase, which has six mutations (E160G/V198I/G36S/T103S/A232S/F277Y). The half-life of this lactate oxidase at 70 °C was about 2 times that of E160G/V198I and about 36 times that of the wild-type enzyme. The amino acid mutation process suggests that the combined neutral mutations are important in protein evolution. Received 15 September 2006; received after revision 21 October 2006; accepted 2 November 2006     

Mechanisms of sperm-egg interactions emerging from gene-manipulated animals

Untangling the molecular nature of sperm-egg interactions is fundamental if we are to understand fertilization. These phenomena have been studied for many years using biochemical approaches such as antibodies and ligands that interact with sperm or with eggs and their vestments. However, when homologous genetic recombination techniques were applied, most of the phenotypic factors of the gene-manipulated animals believed “essential” for fertilization were found to be dispensable. Of course, all biological systems contain redundancies and compensatory mechanisms, but as a whole the old model of fertilization clearly requires significant modification. In this review, we use the results of gene manipulation experiments in animals to propose the basis for a new vision. Received 26 January 2007; received after revision 7 March 2007; accepted 17 April 2007     

Common Molecular Mechanisms of Mammary Gland Development and Breast Cancer

During its lifetime, the mammary gland undergoes many phases of development and differentiation. Much of this occurs during puberty, when the ductal epithelium expands by branching morphogenesis, invading the surrounding fat pad to form an organised mammary tree. Throughout its existence, the epithelium will go through several cycles of proliferation and cell death during pregnancy, lactation and involution. Many of the signalling mechanisms which control the initial invasion of the fat pad by the epithelium, and regulate its continuing plasticity, can be harnessed or corrupted by tumour cells in order to support their aberrant growth and progression towards invasion. This is true not just for the epithelial cells themselves but also for cells in the surrounding microenvironment, including fibroblasts, macrophages and adipocytes. This review examines the complex web of signalling and adhesion interactions controlling branching morphogenesis, and how their alteration can promote malignancy. Current in vivo and in vitro mammary gland models are also discussed. (Part of a Multi-author Review)     

Telomeres and meiosis in health and disease

Telomeres are important segments of chromosomes that protect chromosome ends from nucleolytic degradation and fusion. At meiosis telomeres display an unprecedented behavior which involves their attachment and motility along the nuclear envelope. The movements become restricted to a limited nuclear sector during the so-called bouquet stage, which is widely conserved among species. Recent observations suggest that telomere clustering involves actin and/or microtubules, and is altered in the presence of impaired recombinogenic and chromosome related functions. This review aims to provide an overview of what is currently known about meiotic telomere attachment, dynamics and regulation in synaptic meiosis.     

The Three-component One-pot Synthesis of 4,6-Diarylpyrimidin-2(1h)-ones and 9-Phenyl-8-oxa-10,12-diaza-tricyclo[7.3.1.0~(2,7)]trideca-2(7),3,5-trien-11-one

1 Results Pyrimidinones (PMs) are a class of important heterocycles which have been well documented throughout the literature due to their biological importance. They exhibit a wide range of pharmaceutical and therapeutic properties[1].A rapid and efficient one-pot method for the synthesis of 4,6-diarylpyrimidin-2(1H)- ones and related heterocycles is described.The condensation of acetophenone derivatives,aldehydes and urea in the presence of sulfamic acid was employed to synthesize a variety of pyrimid...