Expression Analysis of an R3-Type MYB Transcription Factor CPC-LIKE MYB4 (TRICHOMELESS2) and CPL4-Related Transcripts in Arabidopsis

The CAPRICE (CPC)-like MYB gene family encodes R3-type MYB transcription factors in Arabidopsis. There are six additional CPC-like MYB sequences in the Arabidopsis genome, including TRYPTICHON (TRY), ENHANCER OF TRY AND CPC1 and 2 (ETC1 and ETC2), ENHANCER OF TRY AND CPC3/CPC-LIKE MYB3 (ETC3/CPL3), and TRICHOMELESS1 and 2 (TCL1 and TCL2). We independently identified CPC-LIKE MYB4 (CPL4), which was found to be identical to TCL2. RT-PCR analysis showed that CPL4 is strongly expressed in shoots, including true leaves, but not in roots. Promoter-GUS analyses indicated that CPL4 is specifically expressed in leaf blades. Although CPC expression was repressed in 35S::ETC1, 35S::ETC2 and 35S::CPL3 backgrounds, CPL4 expression was not affected by ETC1, ETC2 or CPL3 over-expression. Notably, several chimeric transcripts may result from inter-genic alternative splicing of CPL4 and ETC2, two tandemly repeated genes on chromosome II. At least two chimeric transcripts named CPL4-α and CPL4-β are expected to encode complete CPC-like MYB proteins

Dynamical Susceptibility in KDP-type Crysals above and below Tc II

The path probability method (PPM) in the tetrahedron-cactus approximation is applied to the Slater-Takagi model with dipole-dipole interaction for KH2PO4-type hydrogen-bonded ferroelectric crystals in order to derive a small dip structure in the real part of dynamical susceptibility observed at the transition temperature Tc. The dip structure can be ascribed to finite relaxation times of electric dipole moments responsible for the first order transition with contrast to the critical slowing down in the second order transition. The light scattering intensity which is related to the imaginary part of dynamical susceptibility is also calculated above and below the transition temperature and the obtained central peak structure is consistent with polarization fluctuation modes in Raman scattering experiments.Comment: 8 pages, 11 figure

The Peculiar Type Ib Supernova 2006jc: A WCO Wolf-Rayet Star Explosion

We present a theoretical model for Type Ib supernova (SN) 2006jc. We calculate the evolution of the progenitor star, hydrodynamics and nucleosynthesis of the SN explosion, and the SN bolometric light curve (LC). The synthetic bolometric LC is compared with the observed bolometric LC constructed by integrating the UV, optical, near-infrared (NIR), and mid-infrared (MIR) fluxes. The progenitor is assumed to be as massive as $40M_\odot$ on the zero-age main-sequence. The star undergoes extensive mass loss to reduce its mass down to as small as $6.9M_\odot$, thus becoming a WCO Wolf-Rayet star. The WCO star model has a thick carbon-rich layer, in which amorphous carbon grains can be formed. This could explain the NIR brightening and the dust feature seen in the MIR spectrum. We suggest that the progenitor of SN 2006jc is a WCO Wolf-Rayet star having undergone strong mass loss and such massive stars are the important sites of dust formation. We derive the parameters of the explosion model in order to reproduce the bolometric LC of SN 2006jc by the radioactive decays: the ejecta mass $4.9M_\odot$, hypernova-like explosion energy $10^{52}$ ergs, and ejected $^{56}$Ni mass $0.22M_\odot$. We also calculate the circumstellar interaction and find that a CSM with a flat density structure is required to reproduce the X-ray LC of SN 2006jc. This suggests a drastic change of the mass-loss rate and/or the wind velocity that is consistent with the past luminous blue variable (LBV)-like event.Comment: 12 pages, 11 figures. Accepted for publication in the Astrophysical Journa

Getting to the root of plant biology: impact of the Arabidopsis genome sequence on root research

Prior to the availability of the genome sequence, the root of Arabidopsis had attracted a small but ardent group of researchers drawn to its accessibility and developmental simplicity. Roots are easily observed when grown on the surface of nutrient agar media, facilitating analysis of responses to stimuli such as gravity and touch. Developmental biologists were attracted to the simple radial organization of primary root tissues, which form a series of concentric cylinders around the central vascular tissue. Equally attractive was the mode of propagation, with stem cells at the tip giving rise to progeny that were confined to cell files. These properties of root development reduced the normal four-dimensional problem of development (three spatial dimensions and time) to a two-dimensional problem, with cell type on the radial axis and developmental time along the longitudinal axis. The availability of the complete Arabidopsis genome sequence has dramatically accelerated traditional genetic research on root biology, and has also enabled entirely new experimental strategies to be applied. Here we review examples of the ways in which availability of the Arabidopsis genome sequence has enhanced progress in understanding root biology.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79263/1/j.1365-313X.2010.04129.x.pd

The type IIb SN 2008ax: spectral and light curve evolution

We present spectroscopy and photometry of the He-rich supernova (SN) 2008ax. The early-time spectra show prominent P-Cygni H lines, which decrease with time and disappear completely about two months after the explosion. In the same period He I lines become the most prominent spectral features. SN 2008ax displays the ordinary spectral evolution of a type IIb supernova. A stringent pre-discovery limit constrains the time of the shock breakout of SN 2008ax to within only a few hours. Its light curve, which peaks in the B band about 20 days after the explosion, strongly resembles that of other He-rich core-collapse supernovae. The observed evolution of SN 2008ax is consistent with the explosion of a young Wolf-Rayet (of WNL type) star, which had retained a thin, low-mass shell of its original H envelope. The overall characteristics of SN 2008ax are reminiscent of those of SN 1993J, except for a likely smaller H mass. This may account for the findings that the progenitor of SN 2008ax was a WNL star and not a K supergiant as in the case of SN 1993J, that a prominent early-time peak is missing in the light curve of SN 2008ax, and that Halpha is observed at higher velocities in SN 2008ax than in SN 1993J.Comment: 10 pages, including 8 figures and 4 tables. Accepted for publication in MNRA

A subcellular tug of war involving three MYB-like proteins underlies a molecular antagonism in Antirrhinum flower asymmetry

The establishment of meristematic domains with different transcriptional activity is essential for many developmental processes. The asymmetry of the Antirrhinum majus flower is established by transcription factors with an asymmetric pattern of activity. To understand how this asymmetrical pattern is established, we studied the molecular mechanism through which the dorsal MYB protein RADIALIS (RAD) restricts the activity of the MYB transcription factor DIVARICATA (DIV) to the ventral region of the flower meristem. We show that RAD competes with DIV for binding with other MYB-like proteins, termed DRIF1 and DRIF2 (DIV- and-RAD-interacting-factors). DRIF1 and DIV interact to form a protein complex that binds to the DIV-DNA consensus region, suggesting that the DRIFs act as co-regulators of DIV transcriptional activity. In the presence of RAD, the interaction between DRIF1 and DIV bound to DNA is disrupted. Moreover, the DRIFs are sequestered in the cytoplasm by RAD, thus, preventing or reducing the formation of DRIF-DIV heterodimers in the nuclei. Our results suggest that in the dorsal region of the Antirrhinum flower meristem the dorsal protein RAD antagonises the activity of the ventral identity protein DIV in a subcellular competition for a DRIF protein promoting the establishment of the asymmetric pattern of gene activity in the Antirrhinum flower.- We are grateful to Roger Tsien for providing the plasmids with red fluorescent protein, Barry Causier and Brendan Davies for help in the screening of the Antirrhinum yeast-two hybrid library and Ulises Rosas for providing part of the cDNA sequence for DRIF2. We also thank Nicolas Arnaud and Alejandro Ferrando for providing BiFC plasmids, Desmond Bradley and Alexandra Rebocho for helpful comments on the manuscript and Lucilia Goreti Pinto and Grant Calder for helping with the confocal microscopy. This work was funded by FCT/COMPETE/FEDER with a project grant (ref. FCOMP-01-0124-FEDER-008818) and with a Royal Society International Joint Project grant (2008/R2). JR was supported by funding from FCT with a PhD grant (ref. SFRH/BD/75050/2010). The authors have no conflict of interest to declare

Distinct relationships between GLABRA2 and single-repeat R3 MYB transcription factors in the regulation of trichome and root hair patterning in Arabidopsis

• The patterning of epidermal cell types in Arabidopsis is an excellent model for studying the molecular basis of cell specification. Trichome and root hair formation is controlled by a transcriptional activator complex that induces the homeobox gene GLABRA2 (GL2) and some single-repeat R3 MYB genes (single MYB ). However, it remains unclear how the actions of GL2 and single MYBs are coordinated to regulate epidermal patterning. • GL2 is thought to act downstream of single MYBs to regulate trichome and root hair development. In order to test this hypothesis genetically, double and higher order mutants between gl2 and single myb were generated. • In these mutants, the glabrous phenotypes observed in the gl2 single mutants were partially recovered, suggesting that single MYBs may not act solely through GL2 to regulate trichome development. On the other hand, double and higher order mutants between gl2 and single myb phenocopied the root hair phenotype of gl2 single mutants, suggesting that GL2 and single MYBs act in a common pathway to regulate root hair patterning. • These findings reveal distinct relationships between GL2 and single MYBs in the regulation of trichome vs root hair development, and provide new insights into the molecular mechanism of epidermal patterning.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78641/1/j.1469-8137.2009.03067.x.pd

Intracellular mechanisms underlying the nicotinic enhancement of LTP in the rat dentate gyrus

We have previously shown that activation of nicotinic acetylcholine receptors (nAChRs) enhanced long-term potentiation (LTP) in the rat dentate gyrus in vitro via activation of α7 nAChR. In the present studies, mechanisms underlying the acute and chronic nicotinic enhancement of LTP were examined. In particular, the involvement of activation of intracellular kinases was examined using selective kinase antagonists, and the effects of enhancing cholinergic function with positive allosteric modulators of the α7 nAChR and with acetylcholinesterase (AChE) inhibitors were also investigated. Activation of extracellular signal-regulated kinase (ERK) and cAMP-dependent protein kinase (PKA) was found to be involved in the induction of the acute nicotinic enhancement of LTP, although not control LTP. In contrast, activation of the tyrosine kinase Src, Ca2+-calmodulin-dependent protein kinase II, Janus kinase 2 and p38 mitogen-activated protein kinase was not involved in the acute nicotinic enhancement of LTP, although Src activation was necessary for control LTP. Moreover, activation of phosphoinositide 3-kinase was involved in the acute nicotinic enhancement of LTP to a much lesser extent than in control LTP. Chronic nicotine enhancement of LTP was found to be dependent on PKA, ERK and Src kinases. Acute nicotinic enhancement of LTP was occluded by chronic nicotine treatment. The positive allosteric modulator PNU-120596 was found to strongly reduce the threshold for nicotinic enhancement of LTP, an affect mediated via the α7 nAChR as it was blocked by the selective antagonist methyllycaconitine. The AChE inhibitors tacrine and physostigmine enhanced control LTP

Clinical Efficacy and Safety of Sitafloxacin 200 mg Once Daily for Refractory Genitourinary Tract Infections

The aim of this ongoing trial is to evaluate the clinical efficacy and safety of sitafloxacin (STFX) 200 mg once daily (QD) for 7 days in patients with refractory genitourinary tract infections, which include recurrent or complicated cystitis, complicated pyelonephritis, bacterial prostatitis, and epididymitis. The primary endpoint is the microbiological efficacy at 5-9 days after the last administration of STFX. Recruitment began in February 2021, and the target total sample size is 92 participants

Influence of Population III stars on cosmic chemical evolution

New observations from the Hubble ultra deep field suggest that the star formation rate at z>7 drops off faster than previously thought. Using a newly determined star formation rate for the normal mode of Population II/I stars (PopII/I), including this new constraint, we compute the Thomson scattering optical depth and find a result that is marginally consistent with WMAP5 results. We also reconsider the role of Population III stars (PopIII) in light of cosmological and stellar evolution constraints. While this input may be needed for reionization, we show that it is essential in order to account for cosmic chemical evolution in the early Universe. We investigate the consequences of PopIII stars on the local metallicity distribution function of the Galactic halo (from the recent Hamburg/ESO survey of metal-poor stars) and on the evolution of abundances with metallicity (based on the ESO large program on very metal-poor stars), with special emphasis on carbon-enhanced metal-poor stars. Our most important results show that the nucleosynthetic yields of PopIII stars lead to abundance patterns in agreement with those observed in extremely metal-poor stars. In this chemical approach to cosmic evolution, PopIII stars prove to be a compulsory ingredient, and extremely metal-poor stars are inevitably born at high redshift. (Abridged)Comment: 11 pages, 7 figures, MNRAS in pres