Immortalization of human T lymphocytes after transfection of Epstein-Barr virus DNA

Epstein-Barr virus (EBV), a ubiquitous human herpesvirus, has the ability to transform human B lymphocytes. No other cell type has been experimentally transformed by EBV, either by intact virions or naked viral DNA and subgenomic fragments. Two immortalized human T-lymphoblastoid cell lines have now been established by transfecting cord blood lymphocytes with purified B95-8 viral DNA enclosed in fusogenic Sendai virus envelopes (RSVE) and then exposing the cells to EBV from a P3HR-1 cell subclone. One of these lines, which has been fully characterized, is termed HBD-1. This line is positive for EBV DNA and expresses surface OKT11, OKT4, and Tac receptors, but not M-1, mu immunoglobulin chains, EBV receptors, or B-1 surface markers. The cells contain fully rearranged T-cell receptor genes and germline immunoglobulin genes. The karyotype of the cells is normal, they do not require interleukin-2 for growth, and do not contain human T-lymphotropic virus type I. However, the HBD-1 cells contain incomplete EBV genomes and express several EBV-determined antigens, including the early antigen type D, membrane antigens, but not EBV-determined nuclear antigen (EBNA). This association of the EBV genome with permanently growing hematopoietic cells of non B-cell lineage should prove useful in studies on the mechanism of EBV-mediated cell transformation.     

Quiescent T lymphocytes as an inducible virus reservoir in HIV-1 infection

To better understand the basis for human immunodeficiency virus type 1 (HIV-1) persistence and latency, the form in which viral DNA exists in the peripheral T lymphocyte reservoir of infected individuals was investigated. In asymptomatic individuals, HIV-1 was harbored predominantly as full-length, unintegrated complementary DNA. These extrachromosomal DNA forms retained the ability to integrate upon T cell activation in vitro. In patients with acquired immunodeficiency syndrome (AIDS), there was an increase in integrated relative to extrachromosomal DNA forms. By analysis of DNA from patient lymphocyte subpopulations depleted of human lymphocyte antigen-Dr receptor-positive cells, quiescent T cells were identified as the source of extrachromosomal HIV-1 DNA. Thus quiescent T lymphocytes may be a major and inducible HIV-1 reservoir in infected individuals.     

"Coulomb Staircase" at Room Temperature in a Self-Assembled Molecular Nanostructure

Double-ended aryl dithiols [alpha,alpha'-xylyldithiol (XYL) and 4,4'-biphenyldithiol] formed self-assembled monolayers (SAMs) on gold(111) substrates and were used to tether nanometer-sized gold clusters deposited from a cluster beam. An ultrahigh-vacuum scanning tunneling microscope was used to image these nanostructures and to measure their current-voltage characteristics as a function of the separation between the probe tip and the metal cluster. At room temperature, when the tip was positioned over a cluster bonded to the XYL SAM, the current-voltage data showed "Coulomb staircase" behavior. These data are in good agreement with semiclassical predictions for correlated single-electron tunneling and permit estimation of the electrical resistance of a single XYL molecule (approximately18 ± 12 megohms).     

Neodymium-142 evidence for Hadean mafic crust

Neodymium-142 data for rocks from the Nuvvuagittuq greenstone belt in northern Quebec, Canada, show that some rock types have lower 142Nd/144Nd ratios than the terrestrial standard (epsilon142Nd = -0.07 to -0.15). Within a mafic amphibolite unit, 142Nd/144Nd ratios correlate positively with Sm/Nd ratios and produce a 146Sm-142Nd isochron with an age of 4280(-81)(+53) million years. These rocks thus sample incompatible-element-enriched material formed shortly after Earth formation and may represent the oldest preserved crustal section on Earth.     

Planetary science. Europa's ocean--the case strengthens

The possibility of a subsurface ocean on Jupiter's moon Europa has been suggested on the basis of theoretical, geological, and spectroscopic arguments. But, as Stevenson explains in his Perspective, none of these arguments were compelling. In contrast, the magnetic field data obtained by the Galileo spacecraft and presented in the report by Kivelson et al., provide persuasive evidence for a conducting layer--most likely a global water ocean--near Europa's surface.     

On the Presence of Fixed Ammonium in Rocks

From one-fourth to one-half of the nitrogen in some granite rocks, and up to two-thirds of that in some paleozoic shales, occurred as ammonium ions held within the lattice structure of silicate minerals. The results provide greater insight into the origin of the earth's atmosphere.