Class-switch recombination (CSR) is a DNA recombination process that replaces the immunoglobulin (Ig) constant region for the isotype that can best protect against the pathogen. Dysregulation of CSR ...can cause self-reactive BCRs and B cell lymphomas; understanding the timing and location of CSR is therefore important. Although CSR commences upon T cell priming, it is generally considered a hallmark of germinal centers (GCs). Here, we have used multiple approaches to show that CSR is triggered prior to differentiation into GC B cells or plasmablasts and is greatly diminished in GCs. Despite finding a small percentage of GC B cells expressing germline transcripts, phylogenetic trees of GC BCRs from secondary lymphoid organs revealed that the vast majority of CSR events occurred prior to the onset of somatic hypermutation. As such, we have demonstrated the existence of IgM-dominated GCs, which are unlikely to occur under the assumption of ongoing switching.
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•Germline transcripts peak prior to GC formation and rapidly decline in GCs•IgM-dominated clones are found in late GCs, arguing against ongoing Ig switching•CSR largely ceases upon the onset of somatic hypermutation•CSR decline due to low GLT and APE1 expression is possibly orchestrated by BCL6
Germinal centers (GCs) have long been considered sites in which Ig class-switch recombination (CSR) is favored. Roco et al. show that CSR occurs during the initial T cell:B cell interaction prior to GC formation and rapidly declines as B cells differentiate into GC cells and somatic hypermutation commences.
Traditional functional genetic studies in crops are time consuming, complicated and cannot be readily scaled up. The reason is that mutant or transformed crops need to be generated to study the ...effect of gene modifications on specific traits of interest. However, many crop species have a complex genome and a long generation time. As a result, it usually takes several months to over a year to obtain desired mutants or transgenic plants, which represents a significant bottleneck in the development of new crop varieties. To overcome this major issue, we are currently establishing a versatile plant genetic screening platform, amenable to high throughput screening in almost any crop species, with a unique workflow. This platform combines protoplast transformation and fluorescence activated cell sorting. Here we show that tobacco protoplasts can accumulate high levels of lipid if transiently transformed with genes involved in lipid biosynthesis and can be sorted based on lipid content. Hence, protoplasts can be used as a predictive tool for plant lipid engineering. Using this newly established strategy, we demonstrate the major role of
in plant lipid accumulation. We anticipate that this workflow can be applied to numerous highly valuable metabolic traits other than storage lipid accumulation. This new strategy represents a significant step toward screening complex genetic libraries, in a single experiment and in a matter of days, as opposed to years by conventional means.
The exact function(s) of the lagovirus non-structural protein p23 is unknown as robust cell culture systems for the
Rabbit haemorrhagic disease virus
(RHDV) and other lagoviruses have not been ...established. Instead, a range of
in vitro
and
in silico
models have been used to study p23, revealing that p23 oligomerizes, accumulates in the cytoplasm, and possesses a conserved C-terminal region with two amphipathic helices. Furthermore, the positional homologs of p23 in other caliciviruses have been shown to possess viroporin activity. Here, we report on the mechanistic details of p23 oligomerization. Site-directed mutagenesis revealed the importance of an N-terminal cysteine for dimerization. Furthermore, we identified cellular interactors of p23 using stable isotope labeling with amino acids in cell culture (SILAC)-based proteomics; heat shock proteins Hsp70 and 110 interact with p23 in transfected cells, suggesting that they ‘chaperone’ p23 proteins before their integration into cellular membranes. We investigated changes to the global transcriptome and proteome that occurred in infected rabbit liver tissue and observed changes to the misfolded protein response, calcium signaling, and the regulation of the endoplasmic reticulum (ER) network. Finally, flow cytometry studies indicate slightly elevated calcium concentrations in the cytoplasm of p23-transfected cells. Taken together, accumulating evidence suggests that p23 is a viroporin that might form calcium-conducting channels in the ER membranes.
To date, not much has been known regarding the role of CD80 and CD86 molecules in signaling of B cells. The CD28/CTLA4 ligands, CD80 (B7-1) and CD86 (B7-2), are expressed on the surface of freshly ...isolated splenic B cells, and their expression is up-regulated by lipopolysaccharides. In the present study, we have investigated whether signaling via CD80/CD86 could alter the proliferation and immunoglobulin synthesis of B cells. Splenic B cells were stimulated with lipopolysaccharides in the presence of anti-B7-1 (16-10A1) and anti-B7-2 (GL1) monoclonal antibodies (mAbs). Exciting features observed during the study were that cross-linking of CD86 with GL1 enhanced the proliferation and production of IgG1 and IgG2a isotypes. In contrast, anti-B7-1 (16-10A1) mAb could efficiently block the proliferation and production of IgG1 and IgG2a. Furthermore, GL1 mAb could also induce the secretion of IgG isotypes from B cell lymphomas. Importantly, 16-10A1 could retard the growth of lymphomas and favored the up-regulation of pro-apoptotic molecules caspase-3, caspase-8, Fas, FasL, Bak, and Bax and down-regulation of anti-apoptotic molecule Bcl-x(L). In contrast, GL1 augmented the level of anti-apoptotic molecules Bcl-w and Bcl-x(L) and decreased the levels of pro-apoptotic molecule caspase-8, thereby providing a novel insight into the mechanism whereby triggering through CD80 and CD86 could deliver regulatory signals. Thus, this study is the first demonstration of a distinct signaling event induced by CD80 and CD86 molecules in B cell lymphoma. Finally, the significance of the finding is that CD80 provided negative signal for the proliferation and IgG secretion of normal B cells and B cell lymphomas. In contrast, CD86 encouraged the activity of B cells.
This study discusses an integrated authentication and encryption (LoSWIAE) scheme for medical wireless sensor networks (MWSNs). A scalable watermarking-based solution promises amalgamated advantages ...offered by both encryption and authentication schemes in MWSNs but at much lower costs. Furthermore, unlike encryption, the proposed scheme does not require an encryption–decryption key to be exchanged before communication. LoSWIAE ensures nonrepudiation, confidentiality, and protection against eavesdropping in addition to node and data authentication. The scheme’s strength lies in the node’s geographical credentials, temporal credentials of the message, and basic information captured by the sensor node. Parameters used to check the scheme’s robustness are cracking probability and communication overhead. Analytical results obtained compared to an earlier scheme show the effectiveness of LoSWIAE. It proves to have better efficiency and an improvement of the order of 1,032 at the cost of infinitesimal communication overhead. KCI Citation Count: 0
•The critical contributions of the proposed test solution development technique include.•Development of an integrated modular core-based test solution for the coarse grain partitioned 3D ...SoC.•Optimization of test architecture of individual die and complete stack on the basis of allowed intractability.•Minimization of the test cost in terms of testing time, test power, and Through Silicon Via requirements.•Support of pre, partial, and post bond testing.
The occurrence of manufacturing defects in complex 3D System-on-Chip can affect their performance and functionality. Massive test data is required to test such systems, which increases testing time. This paper presents an efficient heuristic-based solution that addresses test architecture development for both fixed and flexible design scenarios in coarse-grain partitioned 3D Systems-on-Chip. The algorithm minimizes the test times at inter and intra die levels while addressing the various constraints. It works in two stages: initially, it prepares a tentative test architecture for individual dies with fixed test widths. Later, a solution for the allotment of the test wires to separate dies is made such that the test time of the complete stack reduces. Experiments performed using different ITC’02 SoC benchmark circuits show the effectiveness of the proposed solutions. The resultant test time is comparable to the lower bounds of test time of the complete 2D benchmark.
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Streptococcus pyogenes causes pharyngitis in school age children, which if left untreated causes acute rheumatic fever (ARF) that later progress toward rheumatic heart disease (RHD). The pathogenesis ...of this disease and its progression as post infectious squeal is not well understood. In this study, percentages of CD4+ and CD8+ T-cells were compared among patients of ARF, RHD and Chronic RHD using flow cytometer. The production of Th1/Th2 cytokines from serum and endothelial cells of damaged and normal heart valves was also analyzed using flow cytometer. Results showed an inverse proportion of CD4+ and CD8+ T-cell numbers in ARF and RHD patients. Cytokine assay demonstrated a switch-over from Th1 to Th2 type, as the disease progressed. We observed significantly high IL-6 in ARF patients and high TNF-α in early RHD patients which allowed us to construct a hypothesis, that, during initial infection phase, lot of antibodies are produced (via IL-6) and TNF-α has a role in disease progression and tissue damage during RHD phase.
Manufacturing of semiconductor devices at the sub-micron level has led to the introduction of huge number of faults. To ensure the quality of integrated circuits (ICs), enormous amount of test data ...is needed which, in turn, increases the overall test cost of the ICs. This study presents a hierarchical block-merging-based technique (HBMT) for test data compression, which appropriately encodes the test pattern blocks of fixed sizes at inter- and intra-block levels using lesser number of bits. The proposed technique works in four steps: segmentation of the entire length of test data into equal length blocks; categorisation of test blocks as compatible blocks and unique blocks; merging of compatible blocks to form representative pattern block, which is further merged at sub-block level; and compression of the non-compatible (unique) blocks using different encoding cases. Experimental results performed on various international symposium for circuits and systems (ISCAS)’ 89 benchmark circuits demonstrate the effectiveness of the proposed test data compression technique. It is found that application of HBMT can improve the compression efficiency by an average of 73% along with a reduction in the test application time. This study also presents the decoder architecture.
The 3D System-on-chip (SoC) technology supports the vertical interconnectivity required for the purpose of functional, supply and test access purposes through the use of Through Silicon Vias (TSVs). ...Little number of available TSVs for test purpose necessitates the optimization of test infrastructure. This paper proposes an algorithm to design the test wrapper for the 3D cores such that the number of the TSVs used per TAM chain are minimized. Test time optimization is done by balancing the lengths of the individual Wrapper chain inside the core. The proposed heuristic firstly distributes the different core elements on the given TAM chains and then uses a diagraph for their insertion ordering to get minimum possible TSV utilization. Simulation results are presented for the different cores of the ITC’02 SoC benchmark circuits. Results show that TSVs can be reduced to 20-30 percent with around 60-70 percent reduction in CPU time utilization for heavy SoCs in comparison to the other proposed techniques.
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