Earthquake nucleation in the lower crust by local stress amplification

Deep intracontinental earthquakes are poorly understood, despite their potential to cause significant destruction. Although lower crustal strength is currently a topic of debate, dry lower continental crust may be strong under high-grade conditions. Such strength could enable earthquake slip at high differential stress within a predominantly viscous regime, but requires further documentation in nature. Here, we analyse geological observations of seismic structures in exhumed lower crustal rocks. A granulite facies shear zone network dissects an anorthosite intrusion in Lofoten, northern Norway, and separates relatively undeformed, microcracked blocks of anorthosite. In these blocks, pristine pseudotachylytes decorate fault sets that link adjacent or intersecting shear zones. These fossil seismogenic faults are rarely >15 m in length, yet record single-event displacements of tens of centimetres, a slip/length ratio that implies >1 GPa stress drops. These pseudotachylytes represent direct identification of earthquake nucleation as a transient consequence of ongoing, localised aseismic creep

Whole Genome Resequencing Reveals Natural Target Site Preferences of Transposable Elements in Drosophila melanogaster

Transposable elements are mobile DNA sequences that integrate into host genomes using diverse mechanisms with varying degrees of target site specificity. While the target site preferences of some engineered transposable elements are well studied, the natural target preferences of most transposable elements are poorly characterized. Using population genomic resequencing data from 166 strains of Drosophila melanogaster, we identified over 8,000 new insertion sites not present in the reference genome sequence that we used to decode the natural target preferences of 22 families of transposable element in this species. We found that terminal inverted repeat transposon and long terminal repeat retrotransposon families present clade-specific target site duplications and target site sequence motifs. Additionally, we found that the sequence motifs at transposable element target sites are always palindromes that extend beyond the target site duplication. Our results demonstrate the utility of population genomics data for high-throughput inference of transposable element targeting preferences in the wild and establish general rules for terminal inverted repeat transposon and long terminal repeat retrotransposon target site selection in eukaryotic genomes

Failure to demonstrate anti-lymphocytic antibody in serum of patients with AIDS.

Several studies have produced evidence for anti-lymphocytic antibodies (ALA) in AIDS. We attempted to demonstrate ALA by immunofluorescent flow cytometry. Normal human peripheral blood lymphocytes (PBL) and the T-cell line, CEM, were incubated with sera from patients with AIDS, patients with chronic HIV infection and HIV-seronegative blood donors. ALA were not detected in the AIDS sera with fluorescein isothiocyanate (FITC)-labelled rabbit anti-mu, anti-alpha or the F(ab)2 fragment of anti-human gamma. A small number of CEM cells (2%) fluoresced with either AIDS or normal serum. A larger proportion of PBL were immunofluorescent after serum treatment but there was no difference between normal and AIDS serum. We were able to detect ALA in the serum of patients with systemic lupus erythematosus with both CEM and PBL. In contrast, incubation of either CEM or PBL with some AIDS sera, and to a lesser degree normal sera, enhanced the binding of intact FITC-rabbit anti-gamma. Anti-gamma was not bound by CEM cells unexposed to human serum. The binding was blocked by rabbit immunoglobulin, demonstrable with CEM fixed in 1% formalin, and unrelated to the density of CD4 on CEM cells