In vitro assembly of the mouse U14 snoRNP core complex and identification of a 65-kDa box C/D-binding protein

The eukaryotic nucleolus contains a diverse population of small nucleolar RNAs (snoRNAs) that have been categorized into two major families based on evolutionarily conserved sequence elements. U14 snoRNA is a member of the larger, box C/D snoRNA family and possesses nucleotide box C and D consensus sequences. In previous studies, we have defined a U14 box C/D core motif that is essential for intronic U14 snoRNA processing. These studies also revealed that nuclear proteins that recognize boxes C/D are required. We have now established an in vitro U14 snoRNP assembly system to characterize protein binding. Electrophoretic mobility-shift analysis demonstrated that all the sequences and structures of the box C/D core motif required for U14 processing are also necessary for protein binding and snoRNP assembly. These required elements include a base paired 5',3' terminal stem and the phylogenetically conserved nucleotides of boxes C and D. The ability of other box C/D snoRNAs to compete for protein binding demonstrated that the box C/D core motif-binding proteins are common to this family of snoRNAs. UV crosslinking of nuclear proteins bound to the U14 core motif identified a 65-kDa mouse snoRNP protein that requires boxes C and D for binding. Two additional core motif proteins of 55 and 50 kDa were also identified by biochemical fractionation of the in vitro-assembled U14 snoRNP complex. Thus, the U14 snoRNP core complex is a multiprotein particle whose assembly requires nucleotide boxes C and D.     

Magnetic separation — The prospects for superconductivity

Conventional methods of magnet separation are described and the processes which could benefit from the use of superconductors are discussed. These include the use of superconductors in high gradient magnetic separators which is one such area finding commercial applications, and a possible large-scale future application for water purification and waste-water treatment     

Investigation of cure in epoxy resins: Ultrasonic and thermally stimulated current measurements

Acoustic and thermally stimulated current measurements are reported as a function of cure for dicyanodiamide cured epoxy resins. It is found that the acoustic propagation is dominated by the generation of voids and does not directly reflect the extent of cure. In contrast, the thermally stimulated data correlate well with conductivity data, the amplitude of the space charge peak decreasing with increasing degree of cure and the dipole peak shifting to high temperatures as predicted from DSC data. Both methods exhibit potential as NDT methods for cure in resins.     

Methodological considerations in the forbidden toy paradigm.

Designed 2 studies to investigate the forbidden fruit effect in 83 3rd and 4th graders. Results indicate (a) no support for a forbidden fruit effect, (b) that procedural aspects other than the prohibition in the forbidden toy paradigm influenced the child's valuation of the entire toy set, and (c) that there is a necessity for an appropriate comparison condition when using the forbidden toy paradigm. These results are extended to the previous research on the sour grapes effect. (4 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Technical with a small `t': technology and the technicalcommunication major

A recent survey at Clarkson University showed that students consider technical communication the least worthy and the least difficult of the institution's majors. This prejudice is attributed to the student's high regard for technology and its quantitative, problem-solving analysis coupled with conversely low regard for writing. The author describes his experience with the misconceptions and how he came to understand that technical communication is not a contradiction in terms     

Analytic fitting of monoenergetic peaks from Si(Li) X-ray spectrometers

Monoenergetic X-ray lines produced by diffraction from a curved crystal monochromator have been used to test the applicability of the Hypermet function for Si(Li) detectors. Excellent fits are achieved; the function's parameters vary smoothly with energy, and the intensity of the non-Gaussian peak components correlates with the thickness of the frontal dead layer where charge collection is incomplete. Accurate silicon escape peak intensities are presented and the contribution to the lineshape from Compton-scattered events is discussed qualitatively.     

Role of HIF-1alpha in hypoxia-mediated apoptosis, cell proliferation and tumour angiogenesis

As a result of deprivation of oxygen (hypoxia) and nutrients, the growth and viability of cells is reduced. Hypoxia-inducible factor (HIF)-1alpha helps to restore oxygen homeostasis by inducing glycolysis, erythropoiesis and angiogenesis. Here we show that hypoxia and hypoglycaemia reduce proliferation and increase apoptosis in wild-type (HIF-1alpha+/+) embryonic stem (ES) cells, but not in ES cells with inactivated HIF-1alpha genes (HIF-1alpha-/-); however, a deficiency of HIF-1alpha does not affect apoptosis induced by cytokines. We find that hypoxia/hypoglycaemia-regulated genes involved in controlling the cell cycle are either HIF-1alpha-dependent (those encoding the proteins p53, p21, Bcl-2) or HIF-1alpha-independent (p27, GADD153), suggesting that there are at least two different adaptive responses to being deprived of oxygen and nutrients. Loss of HIF-1alpha reduces hypoxia-induced expression of vascular endothelial growth factor, prevents formation of large vessels in ES-derived tumours, and impairs vascular function, resulting in hypoxic microenvironments within the tumour mass. However, growth of HIF-1alpha tumours was not retarded but was accelerated, owing to decreased hypoxia-induced apoptosis and increased stress-induced proliferation. As hypoxic stress contributes to many (patho)biological disorders, this new role for HIF-1alpha in hypoxic control of cell growth and death may be of general pathophysiological importance.     

Malaria and anaemia at different altitudes in the Muheza district of Tanzania: childhood morbidity in relation to level of exposure to infection

Parallel monthly surveys of children aged 6-71 months were conducted in the Muheza district of Tanzania. The aim was to compare highland villages, where the mean, annual entomological inoculation rate (EIR) for malaria is 34 and mean annual prevalences of parasitaemia range from 33%-76%, with culturally similar villages of the lowlands, where the mean EIR is 405 and prevalences of parasitaemia range from 80%-84%. The total survey population could be divided into six geographical subgroups, which can be arranged in order of increasing prevalence of parasitaemia. The prevalences of dense parasitaemia, of febrile malaria, and of anaemia all increased in the same order across this series of groups, the trends being statistically significant. The results of previous studies have indicated a paradoxical effect whereby children in regions with a lower exposure to malarial infection suffer, in the long term, a higher incidence of severe attacks of malaria. In the present study there was no sign of any such paradoxical inverse relationship between the level of exposure and the prevalence of malarial illness or anaemia. However, child mortality rates are similar in the highlands and lowlands, as are the median ages of children admitted to hospital. Overall, the present findings indicate that, for the populations studied, an artificial reduction in EIR would be beneficial, even in the long term, with regard to the chronic effects of malaria. This does not necessarily conflict with previous studies reporting opposite conclusions with regard to the incidence of severe,acute effects.