44 research outputs found

    THE EFFECTS OF POSSIBLE CONTAMINATION ON THE RADIOCARBON DATING OF THE DEAD SEA SCROLLS II THE EFFECTS OF POSSIBLE CONTAMINATION ON THE RADIOCARBON DATING OF THE DEAD SEA SCROLLS II: EMPIRICAL METHODS TO REMOVE CASTOR OIL AND SUGGESTIONS FOR THE EFFECTS O

    No full text
    ABSTRACT. While kept at the Rockefeller Museum in East Jerusalem, many Dead Sea Scroll fragments were exposed to castor oil by the original team of editors in the course of cleaning the parchments. Castor oil must be regarded as a serious contaminant in relation to radiocarbon dating. If modern castor oil is present and is not removed prior to dating, the 14 C dates will be skewed artificially towards modern values. In Rasmussen et al

    Engineering biosynthetic enzymes for industrial natural product synthesis

    No full text

    A morphospace for synthetic organs and organoids: the possible and the actual

    No full text

    Engineering microbial hosts for production of bacterial natural products

    No full text

    Substrate-specific structural rearrangements of human Dicer

    No full text
    Dicer plays a central role in RNA interference pathways by cleaving double-stranded RNAs (dsRNAs) to produce small regulatory RNAs. Human Dicer can process long double-stranded and hairpin precursor RNAs to yield short interfering RNAs (siRNAs) or microRNAs (miRNAs), respectively. Previous studies have shown that pre-miRNAs are cleaved more rapidly than pre-siRNAs in vitro and are the predominant natural Dicer substrates. We have used electron microscopy and single particle analysis of Dicer–RNA complexes to gain insight into the structural basis for human Dicer’s substrate preference. Our studies show that Dicer traps pre-siRNAs in a non-productive conformation, while interactions of Dicer with pre-miRNAs and dsRNA binding proteins induce structural changes in the enzyme that enable productive substrate recognition in the central catalytic channel. These findings implicate RNA structure and cofactors in determining substrate recognition and processing efficiency by human Dicer

    The Effects of Possible Contamination on the Radiocarbon Dating of the Dead Sea Scrolls II: Empirical Methods to Remove Castor Oil and Suggestions for Redating

    Get PDF
    While kept at the Rockefeller Museum in East Jerusalem, many Dead Sea Scroll fragments were exposed to castor oil by the original team of editors in the course of cleaning the parchments. Castor oil must be regarded as a serious contaminant in relation to radiocarbon dating. If modern castor oil is present and is not removed prior to dating, the 14C dates will be skewed artificially towards modern values. Earlier, it was shown that the standard AAA pretreatment procedure used in the 2 previous studies dating Dead Sea Scroll samples is not capable of removing castor oil from parchment samples. In the present work, we show that it is unlikely that castor oil reacts with the amino acids of the parchment proteins, a finding which leaves open the possibility of devising a cleaning method that can effectively remove castor oil. We then present 3 different pretreatment protocols designed to effectively remove castor oil from parchment samples. These involve 3 different cleaning techniques: extraction with supercritical CO2, ultrasound cleaning, and Soxhlet extraction—each with their own advantages and disadvantages. Our data show that the protocol involving Soxhlet extraction is the best suited for the purpose of decontaminating the Dead Sea Scrolls, and we recommend that this protocol be used in further attempts to 14C date the Dead Sea Scrolls. If such an attempt is decided on by the proper authorities, we propose a list of Scroll texts, which we suggest be redated in order to validate the 14C dates done earlier.

    Qumran Textiles in the Palestine Exploration Fund, London: Radiocarbon Dating Results

    Get PDF
    Three pieces of fabric from Qumran’s Cave 1 have been stored in the Palestine Exploration Fund collection since the 1960s but have hitherto never been tested or re-examined. The fabric is made of linen, and was probably used for wrapping or packing scrolls, or sealing jars. New radiocarbon dating on one piece of fabric indicated a probability of 55% for it being made between 1 and 55 A.D., and a probability of 95.4% that it was made between 50 cal B.C.–80 cal A.D.
    corecore