Middle Paleolithic assemblages from the Indian subcontinent before and after the Toba super-eruption

The Youngest Toba Tuff (YTT) eruption, which occurred in Indonesia 74,000 years ago, is one of Earth's largest known volcanic events. The effect of the YTT eruption on existing populations of humans, and accordingly on the course of human evolution, is debated. Here we associate the YTT with archaeological assemblages at Jwalapuram, in the Jurreru River valley of southern India. Broad continuity of Middle Paleolithic technology across the YTT event suggests that hominins persisted regionally across this major eruptive event.     

Capping by branching: a new ribozyme makes tiny lariats

The number of naturally occurring RNA enzymes has just been expanded by the discovery of a new branching ribozyme. But this ribozyme has unexpected relatives: group I introns.     

Isolation of an antigenically "null" cell line from pig peripheral blood mononuclear cells

A new pig cell line (A4) isolated from a primary culture of pig peripheral blood mononuclear cells was characterized. A4 was demonstrated to be morphologically, antigenically and functionally distinct from the more commonly isolated pig lymphoblastoid B cell lines (e.g. P-SC). When the A4 cell line and clones derived from it were tested against a panel of monoclonal antibodies, which define specific subpopulations of pig mononuclear cells, little or no reactivity was observed. The A4 cell line, unlike the P-SC cell line, was unable to induce a mixed lymphocyte reaction. The amount of immunoglobulin secreted by A4 cells as detected by an ELISA was reduced compared to that produced by P-SC cells. The P-SC cell lines produced an IL-1-like factor, whereas no IL-1-like activity was found in the A4 supernatant. The A4 cell line appeared to be a null cell in respect to the P-SC cell line properties; only the slight amount of immunoglobulin produced suggested that the A4 cell line is of the B cell lineage. An association of viral particles with cells of the A4 morphology and null antigenic characteristics was observed and may provide an explanation for the reduced B cell properties of A4 cells.