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

Procontarinia pustulata, a new gall midge species (Diptera: Cecidomyiidae) feeding on mango, Mangifera indica (Anarcadiaceae), in northern Australia and Papua New Guinea

© 2009 The AuthorsProcontarinia pustulata sp. n. is described from northern Australia and Papua New Guinea. Larvae feed on mango Mangifera indica causing blister-like galls on leaves. The new species pupates in the soil. The genus Procontarinia Kieffer & Cecconi contains 15 named and several unnamed species, all of which feed on mango, with several being pests of cultivated mango worldwide. Procontarinia pustulata sp. n. differs from its congeners in morphology and gall anatomy as well as DNA sequence of COI. A simple technique is presented for rearing soil-pupating gall midges in tropical region. © 2009 Australian Entomological Society.Peter Kolesik, Anthony D. Rice, Glenn A. Bellis and Michelle G. Wirthensoh

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

Volume: 98Start Page: 228End Page: 23

De la fiction \ue0 la r\ue9alit\ue9, le b\ue9ton ... \ue9lectrifi\ue9

NRC publication: N