Sex chromosome positions in human interphase nuclei as studied by in situ hybridization with chromosome specific DNA probes

Two cloned repetitive DNA probes, pXBR and CY1, which bind preferentially to specific regions of the human X and Y chromosome, respectively, were used to study the distribution of the sex chromosomes in human lymphocyte nuclei by in situ hybridization experiments. Our data indicate a large variability of the distances between the sex chromosomes in male and female interphase nuclei. However, the mean distance observed between the X and Y chromosome was significantly smaller than the mean distance observed between the two X-chromosomes. The distribution of distances determined experimentally is compared with three model distributions of distances, and the question of a non-random distribution of sex chromosomes is discussed. Mathematical details of these model distributions are provided in an Appendix to this paper. In the case of a human translocation chromosome (XqterXp22.2::Yq11Y qter) contained in the Chinese hamster x human hybrid cell line 445 x 393, the binding sites of pXBR and CY1 were found close to each other in most interphase nuclei. These data demonstrate the potential use of chromosome-specific repetitive DNA probes to study the problem of interphase chromosome topography

High-resolution macromolecular crystallography at the FemtoMAX beamline with time-over-threshold photon detection

Protein dynamics contribute to protein function on different time scales. Ultrafast X-ray diffraction snapshots can visualize the location and amplitude of atom displacements after perturbation. Since amplitudes of ultrafast motions are small, high-quality X-ray diffraction data is necessary for detection. Diffraction from bovine trypsin crystals using single femtosecond X-ray pulses was recorded at FemtoMAX, which is a versatile beamline of the MAX IV synchrotron. The time-over-threshold detection made it possible that single photons are distinguishable even under short-pulse low-repetition-rate conditions. The diffraction data quality from FemtoMAX beamline enables atomic resolution investigation of protein structures. This evaluation is based on the shape of the Wilson plot, cumulative intensity distribution compared with theoretical distribution, I/σ, Rmerge /Rmeas and CC1/2 statistics versus resolution. The FemtoMAX beamline provides an interesting alternative to X-ray free-electron lasers when studying reversible processes in protein crystals

A new species of Dasineura (Diptera: Cecidomyiidae) infesting pinxterbloom azalea flowers in Maryland and Washington, D.C

Volume: 98Start Page: 228End Page: 23

The gall midges (Diptera: Cecidomyiidae) of Mikania glomerata (Asteraceae) in southeastern Brazil

Volume: 103Start Page: 110End Page: 13

Six new species of gall midges (Diptera: Cecidomyiidae) from Melaleuca (Myrtaceae) in Australia

Volume: 99Start Page: 312End Page: 33

A new species of gall midge (Diptera: Cecidomyiidae) from ecuador associated with flowers of Clavija (Theophrastaceae)

Volume: 99Start Page: 110End Page: 11

A temporal analysis of the relation between organisational commitment and work motivation

Meyer, Becker, and Vandenberghe (2004) recently proposed a model linking work motivation to organisational commitment. Two studies tested these links prospectively with employees from a Canadian telecommunications company and from an Italian autoparts company. Self-determination theory provided the framework to measure work motivation, such that measures of external, introjected and identified regulation, and intrinsic motivation were linked to Allen and Meyer's (1990) and to O'Reilly and Chatman's (1986) tripartite models of organisational commitment. We hypothesised that Time 1 motivation would be related to changes in commitment over time, but that Time 1 commitment would not be related to motivational changes over time. Results supported hypotheses for affective and normative commitment, but not for continuance commitment.</span

Cesium-fountain development at the National Research Council of Canada

NRC publication: Ye

Improved 3-D molasses for tall Cs fountains

NRC publication: Ye

Cold atoms and cesium fountains at NRC

NRC publication: Ye