The MtSNF4b subunit of the sucrose non-fermenting-related kinase complex connects after-ripening and constitutive defense responses in seeds of Medicago truncatula

Dormant seeds are capable of remaining alive in the hydrated state for extended periods of time without losing vigor, until environmental cues or after-ripening result in the release of dormancy. Here, we investigated the possible role of the regulatory subunit of the sucrose non-fermenting-related kinase complex, MtSNF4b, in dormancy of Medicago truncatula seeds. Expression of MtSNF4b and its involvement in a high-molecular-weight complex are found in dormant seeds, whereas imbibition of fully after-ripened, non-dormant seeds leads to dissociation of the complex. MtSNF4b is capable of complementing the yeast Δsnf4 mutant and of interacting with the MtSnRK1 α-subunit in a double hybrid system. Transcriptome analyses on freshly harvested and after-ripened RNAi Mtsnf4b and wild-type embryos implicate MtSNF4b in the defense response in hydrated dormant embryonic tissues, affecting the expression of genes encoding enzymes of flavonoid and phenylpropanoid metabolism, WRKY transcription factors and pathogenesis-related proteins. Silencing MtSNF4b also increased the speed of after-ripening during dry storage, an effect that appears to be related to a change in base water potential. No significant difference in ABA content or sensitivity was detected between mutant and wild-type seeds. Pharmacological studies using hexoses and sugar analogs revealed that mannose restored germination behavior and expression of the genes PAL, CHR and IFR in RNAi Mtsnf4b seeds towards that of the wild-type, suggesting that MtSNF4b might act upstream of sugar-sensing pathways. Overall, the results suggest that MtSNF4b participates in regulation of a constitutively activated defense response in hydrated, dormant seeds

New capabilities of the INCL4.6 model implemented into high-energy transport codes

Peer reviewe

Resolving Fine-Scale Heterogeneity of Co-seismic Slip and the Relation to Fault Structure

Fault slip distributions provide important insight into the earthquake process. We analyze high-resolution along-strike co-seismic slip profiles of the 1992 M_w = 7.3 Landers and 1999 M_w = 7.1 Hector Mine earthquakes, finding a spatial correlation between fluctuations of the slip distribution and geometrical fault structure. Using a spectral analysis, we demonstrate that the observed variation of co-seismic slip is neither random nor artificial, but self-affine fractal and rougher for Landers. We show that the wavelength and amplitude of slip variability correlates to the spatial distribution of fault geometrical complexity, explaining why Hector Mine has a smoother slip distribution as it occurred on a geometrically simpler fault system. We propose as a physical explanation that fault complexity induces a heterogeneous stress state that in turn controls co-seismic slip. Our observations detail the fundamental relationship between fault structure and earthquake rupture behavior, allowing for modeling of realistic slip profiles for use in seismic hazard assessment and paleoseismology studies

Superficial simplicity of the 2010 El Mayor–Cucapah earthquake of Baja California in Mexico

The geometry of faults is usually thought to be more complicated at the surface than at depth and to control the initiation, propagation and arrest of seismic ruptures. The fault system that runs from southern California into Mexico is a simple strike-slip boundary: the west side of California and Mexico moves northwards with respect to the east. However, the M_w 7.2 2010 El Mayor–Cucapah earthquake on this fault system produced a pattern of seismic waves that indicates a far more complex source than slip on a planar strike-slip fault. Here we use geodetic, remote-sensing and seismological data to reconstruct the fault geometry and history of slip during this earthquake. We find that the earthquake produced a straight 120-km-long fault trace that cut through the Cucapah mountain range and across the Colorado River delta. However, at depth, the fault is made up of two different segments connected by a small extensional fault. Both segments strike N130° E, but dip in opposite directions. The earthquake was initiated on the connecting extensional fault and 15 s later ruptured the two main segments with dominantly strike-slip motion. We show that complexities in the fault geometry at depth explain well the complex pattern of radiated seismic waves. We conclude that the location and detailed characteristics of the earthquake could not have been anticipated on the basis of observations of surface geology alone

Rôle des oligosaccharides de la famille du raffinose (RFO) dans la vigueur des semences de Medicago truncatula

Rôle des oligosaccharides de la famille du raffinose (RFO) dans la vigueur des semences de Medicago truncatula

The role of oligosaccharides in seed vigour revisited using the legume model Medicago truncatula

The role of oligosaccharides in seed vigour revisited using the legume model Medicago truncatula

Structure of 13^{13}Be probed via secondary beam reactions

The low-lying level structure of the unbound neutron-rich nucleus $^{13}$Be has been investigated via breakup on a carbon target of secondary beams of $^{14,15}$B at 35 MeV/nucleon. The coincident detection of the beam velocity $^{12}$Be fragments and neutrons permitted the invariant mass of the $^{12}$Be+$n$ and $^{12}$Be+$n$+$n$ systems to be reconstructed. In the case of the breakup of $^{15}$B, a very narrow structure at threshold was observed in the $^{12}$Be+$n$ channel. Contrary to earlier stable beam fragmentation studies which identified this as a strongly interacting $s$-wave virtual state in $^{13}$Be, analysis here of the $^{12}$Be+$n$+$n$ events demonstrated that this was an artifact resulting from the sequential-decay of the $^{14}$Be(2$^+$) state. Single-proton removal from $^{14}$B was found to populate a broad low-lying structure some 0.70 MeV above the neutron-decay threshold in addition to a less prominent feature at around 2.4 MeV. Based on the selectivity of the reaction and a comparison with (0-3)$\hbar\omega$ shell-model calculations, the low-lying structure is concluded to most probably arise from closely spaced J$^\pi$=1/2$^+$ and 5/2$^+$ resonances (E$_r$=0.40$\pm$0.03 and 0.85$^{+0.15}_{-0.11}$ MeV), whilst the broad higher-lying feature is a second 5/2$^+$ level (E$_r$=2.35$\pm$0.14 MeV). Taken in conjunction with earlier studies, it would appear that the lowest 1/2$^+$ and 1/2$^-$ levels lie relatively close together below 1 MeV.Comment: 14 pages, 13 figures, 2 tables. Accepted for publication in Physical Review