Long-term cultures of murine fetal liver retain very early B lymphoid phenotype.

Long-term cultures of murine fetal liver have been successfully established using a modification of our in vitro bone marrow culture system (14, 15). Fetal liver cells from midgestation BALB/c embryos were plated onto BAB-14 bone marrow stromal cell-adherent layers. After a 3-5 wk period, cell growth began to increase and these cells were expanded in number on fresh feeder layers. The cultured fetal liver cells were lymphoid in morphology, 5-20% cytoplasmic Ig-positive, but less than 1% surface Ig-positive. Southern blot analysis of the cultured fetal liver cells, as well as cultured bone marrow-derived B cells, demonstrated a population with germline Ig heavy chain loci, possibly representing very early B cell precursors. Abelson murine leukemia virus (A-MuLV) clonal transformants of such cultured fetal liver cells had a phenotypic distribution similar to that seen with fresh fetal liver transformants but distinct from those obtained with the transformation of either cultured or fresh bone marrow. All A-MuLV transformants isolated had rearrangements at the mu heavy chain locus of both chromosomes, irrespective of Ig production. In addition, most mu heavy chain producers had at least one rearranged kappa gene locus. These long-term fetal liver cultures provide large numbers of cells for studying events early in the B lymphocyte lineage. The cultured fetal liver cells retained phenotypic traits similar to fresh fetal liver B cells and distinctive from bone marrow cells cultured under similar conditions

Investigating poultry trade patterns to guide avian influenza surveillance and control: a case study in Vietnam

Live bird markets are often the focus of surveillance activities monitoring avian influenza viruses (AIV) circulating in poultry. However, in order to ensure a high sensitivity of virus detection and effectiveness of management actions, poultry management practices features influencing AIV dynamics need to be accounted for in the design of surveillance programmes. In order to address this knowledge gap, a cross-sectional survey was conducted through interviews with 791 traders in 18 Vietnamese live bird markets. Markets greatly differed according to the sources from which poultry was obtained, and their connections to other markets through the movements of their traders. These features, which could be informed based on indicators that are easy to measure, suggest that markets could be used as sentinels for monitoring virus strains circulating in specific segments of the poultry production sector. AIV spread within markets was modelled. Due to the high turn-over of poultry, viral amplification was likely to be minimal in most of the largest markets. However, due to the large number of birds being introduced each day, and challenges related to cleaning and disinfection, environmental accumulation of viruses at markets may take place, posing a threat to the poultry production sector and to public health

Gamma Ray and Neutron Radiation effects on the electrical and structural properties of n-ZnO/p-CuGaO2 Schottky Diode

This research focuses on the radiation tolerance of ZnO and CuGaO2 based semiconductor application for space borne application. In this research, n-ZnO/p-CuGaO2 based semiconductor devices were fabricated and exposed to gamma rays with increasing total ionizing dose (TID) and neutron fluence at different flux. Based on the I-V properties, the decrease in the turn-on voltage of the diode is noticeable with increasing radiation dose for both gamma and neutron flux exposure. The maximum turn-on-voltage of the fabricated diode was shown to be 1.5 V. Exposure towards gamma, shows that the turn-on is increased to 4.7 V at 200 kGy. However, the effect of neutron flux at 6.5 × 1015 n cm−2 shows a small significant effect on the turn on voltage of 1.7 V after irradiation. Results show moderate mitigation towards irradiation, indicating that n-ZnO/p-CuGaO2 thin film is capable of withstanding harsh radiation environment while still retaining its semiconductor as the changes in band gap ranges between 3 eV to 4 eV at post-irradiation