Effects of monochromatic X-radiation on the membrane of nodes of ranvier under voltage and current clamp conditions

Summary Monochromatic Ag-K_a-radiation decreased irreversibly the peak sodium current in nodes of Ranvier. This decrease occurs only with a delay of about 1000 sec after a threshold dose of about 8 kR has been reached. Potassium current and resting potential are practically not affected.Dedicated to Prof. Dr Dres h.c. Robert Stämpfli on the occasion of his 65th birthday.Supported by Deutsche Forschungsgemeinschaft, SFB 38, Membranforschung Bonn-Bad Godesberg.     

Regulation of HERG (KCNH2) potassium channel surface expression by diacylglycerol

The HERG (KCNH2) channel is a voltage-sensitive potassium channel mainly expressed in cardiac tissue, but has also been identified in other tissues like neuronal and smooth muscle tissue, and in various tumours and tumour cell lines. The function of HERG has been extensively studied, but it is still not clear what mechanisms regulate the surface expression of the channel. In the present report, using human embryonic kidney cells stably expressing HERG, we show that diacylglycerol potently inhibits the HERG current. This is mediated by a protein kinase C-evoked endocytosis of the channel protein, and is dependent on the dynein–dynamin complex. The HERG protein was found to be located only in early endosomes and not lysosomes. Thus, diacylglycerol is an important lipid participating in the regulation of HERG surface expression and function.     

Common genetic variants at the CRAC1 (HMPS) locus on chromosome 15q13.3 influence colorectal cancer risk

We mapped a high-penetrance gene (CRAC1; also known as HMPS) associated with colorectal cancer (CRC) in the Ashkenazi population to a 0.6-Mb region on chromosome 15 containing SCG5 (also known as SGNE1), GREM1 and FMN1. We hypothesized that the CRAC1 locus harbored low-penetrance variants that increased CRC risk in the general population. In a large series of colorectal cancer cases and controls, SNPs near GREM1 and SCG5 were strongly associated with increased CRC risk (for rs4779584, P = 4.44 x 10(-14)).     

Science at Oxford

Faraday demonstrated electromagnetic induction in 1831 using an iron ring wound with two wire coils; on interrupting battery current in one coil, momentary currents arose in the other. Between Faraday's ring and the induction coil, coiled instruments developed via meandering paths. This paper explores the opening phase of that work in the late 1830s, as the iron core, primary wire coil, and secondary wire coil were researched and differentiated. ‘Working knowledge’ (defined by Baird) gained with materials and phenomena was crucial to innovations. To understand these material-based interactions, I experimented with hand-wound coils, along with examining historical texts, drawings, and artefacts. My experience recovered the historical dead-end of two-wire coils and ensuing work with long-coiled single conductors initiated by Faraday and Henry. The shock and spark heightened in these coils provided feedback to the many instrumental configurations tested by Page, Callan, Sturgeon, Bachhoffner, and others. The continuous conductor differentiated into two segments soldered together: a thick short wire carrying battery current and a long thin wire for elevating shocks (voltage). The joined wires eventually separated, yet their transitional connection documents belief that the induced effects depend on continuity. These coiled instruments, with their intertwined histories, show experimental work and understandings in the process of developing. Seeing the nonlinear paths by which these instruments developed deepens our understanding of historical experiences, and of how people learn.     

No evidence of clonal somatic genetic alterations in cancer-associated fibroblasts from human breast and ovarian carcinomas

There is increasing evidence showing that the stromal cells surrounding cancer epithelial cells, rather than being passive bystanders, might have a role in modifying tumor outgrowth. The molecular basis of this aspect of carcinoma etiology is controversial. Some studies have reported a high frequency of genetic aberrations in carcinoma-associated fibroblasts (CAFs), whereas other studies have reported very low or zero mutation rates. Resolution of this contentious area is of critical importance in terms of understanding both the basic biology of cancer as well as the potential clinical implications of CAF somatic alterations. We undertook genome-wide copy number and loss of heterozygosity (LOH) analysis of CAFs derived from breast and ovarian carcinomas using a 500K SNP array platform. Our data show conclusively that LOH and copy number alterations are extremely rare in CAFs and cannot be the basis of the carcinoma-promoting phenotypes of breast and ovarian CAFs.     

全球化,科学词汇和生物学的未来

1 Biology for the 21st Century In a recent article in the New York Times (3/23/05), reporting on yet another upset to received views of the ways in which cells make use of their DNA, a prominent geneticist is quoted as remarking, "biologists have gotten used to the unexpected." Indeed, they have, as indeed, they have had to. Over the last few years, our understanding of molecular and developmental genetics has mutated dramatically in response to ever more complex analyses of ever more abundant and more complex data.     

Situated learning theory versus traditional cognitive learning theory: Why management education should not ignore management learning

This paper describes the differences between situated learning theory (SLT) and traditional cognitive theory (TCT). SLT is distinctive because it perceives learning to be a socially relational rather than a mentalist process. SLT places research attention upon knowledge productionin situ and in the course of work practices rather than upon learning transmission in the classroom. This paper argues that SLT's emphasis on the social context of learning is problematic and ambiguous. SLT sees context as pregiven, which is consistent with modernist thought, but also sees it as emergent, which is more consistent with postmodern thought. The implications of this are discussed and the SLT-TCT debate is used to shed light on management education from the perspective of management learning.     

Birth of a relativistic outflow in the unusual γ-ray transient Swift J164449.3+573451

Active galactic nuclei, which are powered by long-term accretion onto central supermassive black holes, produce relativistic jets with lifetimes of at least one million years, and the observation of the birth of such a jet is therefore unlikely. Transient accretion onto a supermassive black hole, for example through the tidal disruption of a stray star, thus offers a rare opportunity to study the birth of a relativistic jet. On 25 March 2011, an unusual transient source (Swift J164449.3+573451) was found, potentially representing such an accretion event. Here we report observations spanning centimetre to millimetre wavelengths and covering the first month of evolution of a luminous radio transient associated with Swift J164449.3+573451. The radio transient coincides with the nucleus of an inactive galaxy. We conclude that we are seeing a newly formed relativistic outflow, launched by transient accretion onto a million-solar-mass black hole. A relativistic outflow is not predicted in this situation, but we show that the tidal disruption of a star naturally explains the observed high-energy properties and radio luminosity and the inferred rate of such events. The weaker beaming in the radio-frequency spectrum relative to γ-rays or X-rays suggests that radio searches may uncover similar events out to redshifts of z?≈?6.     

Bats associated with inactive mines in the Great Basin

We surveyed bats using echolocation calls near inactive mines in the western Great Basin from 2003 to 2007. We identified 14 species of bats during our surveys, with Myotis lucifugus and Lasionycteris noctivagans found at 9 sites and Myotis evotis and Tadarida brasiliensis at 7 sites; all other species were found at less than one-half of the sites. Euderma maculatum, a state-protected species in Nevada, was recorded at 2 sites. Our work provides information that will be useful in managing bat habitat, especially with regard to mining activities.