The occupation of a box as a toy model for the seismic cycle of a fault

We illustrate how a simple statistical model can describe the quasiperiodic occurrence of large earthquakes. The model idealizes the loading of elastic energy in a seismic fault by the stochastic filling of a box. The emptying of the box after it is full is analogous to the generation of a large earthquake in which the fault relaxes after having been loaded to its failure threshold. The duration of the filling process is analogous to the seismic cycle, the time interval between two successive large earthquakes in a particular fault. The simplicity of the model enables us to derive the statistical distribution of its seismic cycle. We use this distribution to fit the series of earthquakes with magnitude around 6 that occurred at the Parkfield segment of the San Andreas fault in California. Using this fit, we estimate the probability of the next large earthquake at Parkfield and devise a simple forecasting strategy.Comment: Final version of the published paper, with an erratum and an unpublished appendix with some proof

Nsd1 silencing does not alter Asc, Nlrp3, and caspase-1 gene expression.

<p>BMDMs (1×10⁶) were transfected with 100 nM of <i>Nsd1</i> or control silencer siRNA using Lipofectamine 2000. BMDMs (n = 5) were treated with actinomycin D (5 µg/ml) followed by qPCR analysis of remaining mRNA for (A, <i>left</i>) <i>Asc</i> and (A, <i>right</i>) <i>Nlrp3</i>. Dashed line indicates 50% of mRNA remaining. (B) Silenced and non-silenced BMDMs were either untreated (−) or treated (+) with 1 µM of MG-132, a reversible proteasomal inhibitor. ASC, NLRP3, and pro-caspase-1 levels were determined by immunoblotting. β-actin was used to confirm equal loading. (C) 48 hours after silencing, BMDMs were stimulated with LLO (500 ng/ml) for 30 minutes (n = 8). (C, <i>left</i>) <i>Asc</i>, (C, <i>center</i>) <i>Nlrp3,</i> and (C, <i>right)</i> caspase-1 transcription was evaluated by qPCR. qPCR was analyzed using the ΔΔC_T method. Student's t test; <i>P</i><0.05 compared to cells transfected with control siRNA. NS – not significant. (D) Silenced and non-silenced BMDMs were either non-treated or stimulated with LLO (500 ng/ml) for 30 minutes. Immunoblot was performed for ASC, NLRP3, pro-caspase-1. Equal loading was determined using β-actin. * – non-specific bands. Experiments were repeated at least twice.</p

NSD1 does not affect the NF-κB signaling pathway in macrophages

<p>. 1×10⁶ BMDMs were transfected with control silencer or <i>Nsd1</i> siRNA. After 48 hours, BMDMs were untreated (−) or treated overnight with LPS (500 ng/ml). (A) IL-6 was measured by ELISA (n = 8). Student's t-test; (*) <i>P</i><0.05 compared to cells given control siRNA. NS – not significant. (B) BMDMs (1×10⁶) were untreated or stimulated with LLO (500 ng/ml). Cell lysates were collected at the indicated time points. Immunoblotting was performed to determine levels of p-IκB-α. β-actin was used to determine equivalent loading. (C) 1×10⁶ BMDMs were primed with LPS (100 ng/ml) and treated with control silencer or <i>Nsd1</i> siRNA. Also, BMDMs were untreated or stimulated with LLO (500 ng/ml) for 30 minutes. Cell lysates were immunoblotted for pro-IL-1β. β-actin was used to determine equal loading. Experiments were repeated at least twice.</p

NSD1 inhibits LLO-mediated caspase-1 activation and requires functional LLO for the regulation of IL-1β secretion

<p>. 1×10⁶ BMDMs were primed with LPS (100 ng/ml) and treated with control silencer or <i>Nsd1</i> siRNA. Also, BMDMs were untreated or stimulated with LLO (500 ng/ml) for 30 minutes. (A) Caspase-1 activity in BMDMs (1×10⁶) transfected with <i>Nsd1</i> or control silencer siRNA was determined after LLO stimulation by flow cytometry using the fluorescent inhibitor probe FAM-YVAD-FMK (FLICA). Control cells are shown in gray, while cells treated with <i>Nsd1</i> or control siRNA are shown in red and yellow, respectively. Additionally, silenced 1×10⁶ BMDMs were primed with LPS (100 ng/ml) and were untreated or stimulated with LLO (8 µg/ml) for 1 hour. (B, <i>left</i>) RNA was collected and <i>caspase-11</i> transcription was analyzed by qPCR (n = 4). (B, <i>right</i>) Protein was also harvested and pro-caspase-11 translation was measured by immunoblot. β-actin was used to normalize for qPCR and determine equal loading for immunoblot. (C) Hemolytic assay was performed on sheep RBC using varying concentrations of recombinant WT LLO or LLO^W492A. (D-E) 1×10⁶ WT BMDMs were primed with LPS (100 ng/ml) and treated with WT LLO or LLO^W492A (8 µg/ml) for 1 hour. (D) LDH assay was performed to measure cell death induction after treatment. (E) IL-1β levels secreted by BMDMs from WT (n = 3) and <i>Nlrp3</i>^−/− (n = 4) mice were measured by ELISA. (F) IL-1β was measured by ELISA after nigericin (10 µM) stimulation (n = 4). Student's t test; (*) <i>P</i><.05 compared to cells transfected with control siRNA or knockout. NS – not significant. Experiments were repeated at least twice.</p

NSD1 does not impart chromatin modifications at the 5′ end of caspase-1.

<p>BMDMs (5×10⁶) were transfected with 100 mM of <i>Nsd1</i> or control silencer siRNA using Lipofectamine 2000 (n = 6). Following 48 hours, BMDMs were primed with LPS (100 ng/ml) for 2 hours and treated with 8 µg/ml of LLO for 1 hour. Nuclear proteins were isolated from whole cell lysates and an (A) immunoblot was performed for NSD1. Lamin B1 was used to determine equal loading. BMDMs (45 ×10⁶) were treated as previously described in (A). (B) Regions of caspase<i>-1</i> which were analyzed are as follows: (a) -1000 bp upstream of the transcription start site (TSS), (b) +1000 bp downstream of the TSS, and (c) +2000 bp downstream of the TSS. Boxes indicate exons. (C) ChIP was performed for NSD1 followed by qPCR for the indicated regions of caspase<i>-1</i> and <i>Nlrp3</i>. <i>Nlrp3</i> was measured as a negative control. ChIP-qPCR data is represented as mean+SE. A graph was chosen to be representative of two experiments. Additionally, BMDMs (45×10⁶) were transfected with 100 mM of <i>Nsd1</i> or control silencer siRNA using Lipofectamine 2000. Following 48 hours, BMDMs were primed with LPS (100 ng/ml) for 2 hours and treated with 8 µg/ml of LLO for 1 hour. H3K36me2 was analyzed for each region of caspase<i>-1</i> by ChIP-qPCR (n = 2): (D, <i>left</i>) region a, (E) region b, and (F, <i>left</i>) region c. H3K36me3 was also measured for (D, <i>right</i>) region a and (F, <i>right</i>) region c. (G) H3K36me2 of <i>Nlrp3</i> was determined as a negative control. ChIP-qPCR data is represented as mean+SE. Student's t test; <i>P</i><0.05 compared to cells transfected with control siRNA. NS – not significant.</p

Nsd1 is upregulated during LLO stimulation of macrophages.

<p>(A) Displayed peptide stretches are directly adjacent to each other and cover two repeated PHD finger units. Consensus sequences of both PHD finger units based on similarities between <i>Arabidopsis</i> (<i>At</i>) EDM2 and NSD1 in mice (<i>Mm</i>) and humans (<i>Hs</i>). Cys or His residues of the conserved zinc coordinating C4HC3 pattern of PHD fingers are highlighted in grey. The last C of the C-terminal PHD finger unit is replaced by H in EDM2/NSD1-type proteins. Other residues conserved between EDM2 and NSD1 are highlighted in yellow. (B) PHD fingers from EDM2 and NSD1 are shown in red. Methyltransferase domains in EDM2 (ELP) and NSD1 (SET) are shown in green and purple, respectively. A proline rich region in both NSD1 and EDM2 is shown in blue. (C) BMDMs (1×10⁶) from C57BL/6 mice were stimulated with (C, <i>left</i>) LLO (500 ng/ml) (n = 4) for 30 minutes and alum (500 µg/ml) (n = 4) for 6 hours and (C, <i>right</i>) <i>P. aeruginosa</i> (MOI 50) (n = 6) for 1 hour. <i>Nsd1</i> transcription was evaluated by qPCR and analyzed by the ΔΔC_T method. β-actin was used as a normalizing control. Student's t test; (*) <i>P</i><0.05 compared to (−) non-stimulated cells. NS – not significant. (D) Confocal microscopy of BMDMs from C57BL/6 mice untreated or treated with TNF-α (100 ng/ml) or LLO (500 ng/ml). BMDMs were stained with DAPI (blue) and anti-NSD1 (red). Original magnification 63×with an enlargement of 4x. Scale bar = 10 µm. Experiments were repeated at least three times.</p

Listeriolysin O is recognized by the NLRP3 inflammasome.

<p>1×10⁶ BMDMs were primed with LPS (100 ng/ml) for 2 hours. BMDMs were treated with recombinant LLO (8 µg/ml for hemolysis and LDH or 500 ng/ml for IL-1β) or infected with the <i>L. monocytogenes</i> WT, Δ<i>hly</i>, or <i>L.p.</i>FlaA strains MOI 10 for 6 hours after gentamicin (50 µg/ml) medium replacement at 30 minutes. (A) Hemolysis, (B) LDH, and (C) IL-1β were measured for recombinant LLO. (D and F) IL-1β secretion by WT (n = 4), <i>Nlrp3⁻</i>^/− (n = 4) and <i>Nlrc4 </i>^−/− macrophages (n = 4) was analyzed by ELISA. (E and G) Stimulation was repeated, as previously stated, without priming and IL-6 secretion by WT (n = 4), <i>Nlrp3⁻</i>^/− (n = 4) and <i>Nlrc4 </i>^−/− macrophages (n = 4) was determined. Student's t test; (*) <i>P</i><0.05, WT compared to either unprimed or knockout. NS – not significant. Experiments were repeated at least twice.</p