Analysis of Mice Lacking DNaseI Hypersensitive Sites at the 5′ End of the IgH Locus

The 5′ end of the IgH locus contains a cluster of DNaseI hypersensitive sites, one of which (HS1) was shown to be pro-B cell specific and to contain binding sites for the transcription factors PU.1, E2A, and Pax5. These data as well as the location of the hypersensitive sites at the 5′ border of the IgH locus suggested a possible regulatory function for these elements with respect to the IgH locus. To test this notion, we generated mice carrying targeted deletions of either the pro-B cell specific site HS1 or the whole cluster of DNaseI hypersensitive sites. Lymphocytes carrying these deletions appear to undergo normal development, and mutant B cells do not exhibit any obvious defects in V(D)J recombination, allelic exclusion, or class switch recombination. We conclude that deletion of these DNaseI hypersensitive sites does not have an obvious impact on the IgH locus or B cell development

AID-Targeting and Hypermutation of Non-Immunoglobulin Genes Does Not Correlate with Proximity to Immunoglobulin Genes in Germinal Center B Cells

Upon activation, B cells divide, form a germinal center, and express the activation induced deaminase (AID), an enzyme that triggers somatic hypermutation of the variable regions of immunoglobulin (Ig) loci. Recent evidence indicates that at least 25% of expressed genes in germinal center B cells are mutated or deaminated by AID. One of the most deaminated genes, c-Myc, frequently appears as a translocation partner with the Ig heavy chain gene (Igh) in mouse plasmacytomas and human Burkitt's lymphomas. This indicates that the two genes or their double-strand break ends come into close proximity at a biologically relevant frequency. However, the proximity of c-Myc and Igh has never been measured in germinal center B cells, where many such translocations are thought to occur. We hypothesized that in germinal center B cells, not only is c-Myc near Igh, but other mutating non-Ig genes are deaminated by AID because they are near Ig genes, the primary targets of AID. We tested this “collateral damage” model using 3D-fluorescence in situ hybridization (3D-FISH) to measure the distance from non-Ig genes to Ig genes in germinal center B cells. We also made mice transgenic for human MYC and measured expression and mutation of the transgenes. We found that there is no correlation between proximity to Ig genes and levels of AID targeting or gene mutation, and that c-Myc was not closer to Igh than were other non-Ig genes. In addition, the human MYC transgenes did not accumulate mutations and were not deaminated by AID. We conclude that proximity to Ig loci is unlikely to be a major determinant of AID targeting or mutation of non-Ig genes, and that the MYC transgenes are either missing important regulatory elements that allow mutation or are unable to mutate because their new nuclear position is not conducive to AID deamination

Investigations on free-space optical links within SatNEx II

The objective of this paper is to describe recent activities and investigations on FSO and the excellent results achieved within international COST actions (like COST 270, COST 291, COST 297 (HAPCOS)) and the 6th EU-framework programme (like SatNEx and CAPANINA). In a first part, the FSO technology is briefly discussed. Then its behaviour in different networking architectures is explained to elaborate its potential and suitability for the future Next Generation Networks (NGN). In a second part, the recent investigations in airborne and satellite application scenarios are discussed. Then, the short-range FSO systems built for last mile connectivity are explained. Finally, our recent investigation results on modelling the FSO channel under fog conditions and atmospheric turbulence are presented. Additionally, some recent major performance improvement results obtained by employing hybrid systems and using some specific modulation and coding schemes are presented

Air-to-ground quantum communication

Quantum key distribution (QKD) is the first commercial application in the new field of quantum information, with first routine applications in government and financial sectors and with successful demonstrations of trusted node networks. Today, the main goal is efficient long-range key distribution via either quantum repeaters or satellites, with a view to enabling global secure communication. En route to achieving QKD via satellites, a free-space demonstration of secure key distribution was performed between two ground stations, over a distance of 144 km. This scenario is comparable to links between satellites in low Earth orbit and ground stations with respect to both attenuation and fluctuations. However, key exchange with rapidly moving platforms remained to be demonstrated. Here, we prove, for the first time, the feasibility of BB84 QKD between an aeroplane and a ground station. By establishing a stable and low-noise quantum communication channel with the aeroplane moving at 290 km h−1 at a distance of 20 km—that is, 4 mrad s−1—our results are representative of typical communication links to satellites or to high-altitude platforms

Preventing transmission among operating room staff during COVID-19 pandemic: the role of the Aerosol Box and other personal protective equipment.

The COVID-19 pandemic is highly challenging for the operating room staff and healthcare workers in emergency departments. SARS-CoV-2 is a positive-sense single-stranded RNA beta-coronavirus that primarily targets the human respiratory system, with fever, cough, myalgia, and pneumonia as the most common manifestations. However, since SARS-CoV-2 RNA was detected in stool specimens much more attention has been paid to gastrointestinal symptoms such as loss of appetite, nausea, and diarrhea. Furthermore, the expression of ACE-2 receptors in absorptive enterocytes from ileum and colon suggests that these organs should also be considered as a potential high risk for SARS-CoV-2 infection. During aerosol-generating medical procedures (AGMP; e.g. intubating and extubating patients or any surgical procedures), the production of both airborne particles and droplets may increase the risk of infection. In this situation, the surgical staff is strongly recommended to wear personal protective equipment (PPE). A transparent plastic cube, the so-called "Aerosol Box" (AB), has been recently designed to lend further protection against droplets and aerosol exposure during the AGMP

Investigations on free-space optical links within SatNEx II

The objective of this paper is to describe recent activities and investigations on FSO and the excellent results achieved within international COST actions (like COST 270, COST 291, COST 297 (HAPCOS)) and the 6th EU-framework programme (like SatNEx and CAPANINA). In a first part, the FSO technology is briefly discussed. Then its behaviour in different networking architectures is explained to elaborate its potential and suitability for the future Next Generation Networks (NGN). In a second part, the recent investigations in airborne and satellite application scenarios are discussed. Then, the short-range FSO systems built for last mile connectivity are explained. Finally, our recent investigation results on modelling the FSO channel under fog conditions and atmospheric turbulence are presented. Additionally, some recent major performance improvement results obtained by employing hybrid systems and using some specific modulation and coding schemes are presented