We have sampled wild chromosomes from two natural populations of Drosophila melanogaster and obtained flies fully homozygous for the second chromosome, the third chromosome, or both, as well as flies heterozygous for one or both wild chromosomes and balancer chromosomes. Rate of embryogenesis (egg laying to larval hatching) and rate of development ...
Novel cell-sized, supported artificial membranes bearing class I antigens have been prepared by a simple dialysis procedure and then used to study the requirements for antigen recognition by precursor cytotoxic T lymphocytes (CTL). The membranes were made by mixing lipid, H-2 antigen, and C18 alkylated 5 microns silica beads in deoxycholate, and di...
Heparin-binding growth factor-2 (HBGF-2; also known as basic fibroblast growth factor) is mitogenic for most anchorage-dependent cells. It is shown here that HBGF-2 stimulates cell-substratum adhesion and neurite extension in the sympathetic nerve cell line PC12. When HBGF-2 is adsorbed to artificial extracellular matrices consisting of heparin or ...
The role of antigen surface density, and its relationship to the function of the Lyt-2/3 complex, in recognition and triggering of allospecific cytotoxic T lymphocyte (CTL) precursors has been studied by using a novel type of Class I protein-bearing artificial membrane. The cell-size membranes, termed pseudocytes (artificial cells), can be handled ...
We describe findings on the architecture of Drosophila melanogaster mitotic chromosomes, made using a three-dimensional-oriented structural approach. Using high-voltage and conventional transmission electron microscopy combined with axial tomography and digital contrast-enhancement techniques, we have for the first time visualized significant struc...
Lymphoid fetal liver cultures (LFLC) are long-term, nontransformed cultures of early B lymphoid lineage cells which appear developmentally blocked at the pre-B stage in vitro. When injected into severe combined immunodeficient (SCID) mice, cells from LFLC could reconstitute splenic B lymphocytes and serum IgM. T lymphocyte reconstitution was not ob...
Our results indicate that B lymphocytes stimulated with anti-Ig or antigen exhibit repetitive [Ca2+]i transients which persist for hours. The magnitude of these transients favors an important and ongoing role for [Ca2+]i elevation in antigen driven B cell activation. Repetitive Ca2+ transients may prove to be a prevalent mechanism of Ca2+ signaling...
We have applied patch-clamp techniques to on-cell and excised-membrane patches from human retinal pigment epithelial cells in tissue culture. Single-channel currents from at least four ion channel types were observed: three or more potassium-selective channels with single-channel slope conductances near 100, 45, and 25 pS as measured in on-cell pat...
We have used three different methods to map the human liver/bone/kidney alkaline phosphatase (ALPL) locus: (1) Southern blot analysis of DNA derived from a panel of human-rodent somatic cell hybrids; (2) in situ hybridization to human chromosomes; and (3) genetic linkage analysis. Our results indicate that the ALPL locus maps to human chromosome ba...
To compare the helper function of murine T cell clones that secrete IL-2 and IFN-gamma (Th1 cells) or IL-4 and IL-5 (Th2), purified resting B cells were stimulated with F(ab')2 rabbit anti-mouse Ig (RAMG) and rabbit Ig-specific, class II MHC-restricted cloned T cells belonging to the two subsets. Both Th2 clones examined induced strong proliferativ...
