Maternal mowing effect on seed traits of an invasive weed, Erigeron annuus in Farmland

The effect of maternal mowing on seed traits of an invasive weed, Erigeron annuus, in farmland was discussed by comparing mowing plants with intact (no-mowing) plants. The maternal mowing effect resulted in the decrease of seed mass, achene size, pappus length and germination percentage and the increase of variation in achene size, pappus length, dispersal distance and germination non-uniformity. To some extent, the individuals suffered mowing might accelerate the environmental adaptation through the increase of these variations. Our study indicated the mean of mowing in farmland will restrain the growth and reproduction of weed E. annuus. However, it also increases the diversity of seeds through a more unequal provision to seeds that shares the risk and increases fitness to a wider range of heterogeneity of farmland condition

Imprint of the stochastic nature of photon emission by electrons on the proton energy spectra in the laser-plasma interaction

The impact of stochasticity effects (SEs) in photon emissions on the proton energy spectra during laser-plasma interaction is theoretically investigated in the quantum radiation-dominated regime, which may facilitate SEs experimental observation. We calculate the photon emissions quantum mechanically and the plasma dynamics semiclassically via two-dimensional particle-in-cell simulations. An ultrarelativistic plasma generated and driven by an ultraintense laser pulse head-on collides with another strong laser pulse, which decelerates the electrons due to radiation-reaction effect and results in a significant compression of the proton energy spectra because of the charge separation force. In the considered regime the SEs are demonstrated in the shift of the mean energy of the protons up to hundreds of MeV. This effect is robust with respect to the laser and target parameters and measurable in soon available strong laser facilities

The radiosensitization effects of Endostar on human lung squamous cancer cells H-520

<p>Abstract</p> <p>Background</p> <p>The present study mainly aimed to investigate the direct effects of Endostar (ES) on the proliferation and radiosensitivity of human lung squamous cancer cell line H-520.</p> <p>Results</p> <p>ES significantly inhibited H-520 cell proliferation in a time- and dose-dependent manner. According to the colony-forming assays, ES could increase the H-520 cell radiosensitivity. ES induced cell apoptosis, the apoptosis rate increased with the raise of ES concentration. Irradiation induced significantly higher apoptosis rate in ES-treated H-520 cells than non-treated H-520 cells. ES induced cell cycle distribution and G₀/G₁arrest in H-520 cells, whereas irradiation induced G₂/M arrest. The phospho-p38-MAPK and p-Akt protein levels were decreased in H-520 cells after ES treatment. Furthermore, activated caspase protein level increased and Bcl-2 protein levels decreased after treatment with ES and irradiation.</p> <p>Conclusion</p> <p>ES significantly enhanced the sensitivity of H-520 cells to irradiation by inhibition of cellular proliferation, promotion of cell apoptosis and redistribution of cell cycle, possibly via deactivation of Akt pathway. The present study supports the possibility to use the combination of ES and ionizing irradiation to treat patients with lung squamous cell cancer in clinics.</p

An intrinsic link between long-term UV/optical variations and X-ray loudness in quasars

Observations have shown that UV/optical variation amplitude of quasars depend on several physi- cal parameters including luminosity, Eddington ratio, and likely also black hole mass. Identifying new factors which correlate with the variation is essential to probe the underlying physical processes. Combining ~ten years long quasar light curves from SDSS stripe 82 and X-ray data from Stripe 82X, we build a sample of X-ray detected quasars to investigate the relation between UV/optical variation amplitude ($\sigma_{rms}$) and X-ray loudness. We find that quasars with more intense X-ray radiation (com- pared to bolometric luminosity) are more variable in UV/optical. Such correlation remains highly significant after excluding the effect of other parameters including luminosity, black hole mass, Ed- dington ratio, redshift, rest-frame wavelength (i.e., through partial correlation analyses). We further find the intrinsic link between X-ray loudness and UV/optical variation is gradually more prominent on longer timescales (up to 10 years in the observed frame), but tends to disappear at timescales < 100 days. This suggests a slow and long-term underlying physical process. The X-ray reprocessing paradigm, in which UV/optical variation is produced by a variable central X-ray emission illuminating the accretion disk, is thus disfavored. The discovery points to an interesting scheme that both the X-ray corona heating and UV/optical variation is quasars are closely associated with magnetic disc turbulence, and the innermost disc turbulence (where corona heating occurs) correlates with the slow turbulence at larger radii (where UV/optical emission is produced).Comment: 9 pages, 4 figures, 1 table, accepted by Ap

The importance of population origin and reciprocal heterogeneous microhabitat on clonal propagation of Iris japonica Thunb.

A reciprocal transplant-replant experiment was carried out to investigate the clonal plasticity and local specialization of OAFE population (O type) and BF population (U type) of a clonal rhizome herb Iris japonica in contrasting reciprocal heterogeneous habitats on Jinyun Mountain. U Population had better performance of plant size and clonal propagation (including allocation to clonal propagation, daughter ramet and fine rhizome) in different reciprocal heterogeneous habitats than O population. Both the population origin and reciprocal spatial heterogeneous habitat had effects on clonal ramets and biomass of clonal components of experimental plants. The plasticity of clonal growth had difference in clonal components to balance High light-Low soil resources (water) (HL) or Low light-High soil resources (LH) due to the ecological isolation of the two I. japonica populations. Our findings indicated that two major types of patterns of spatial covariance of resources can have different effects on the growth and local variation of clonal plants

Dynamics of diversity, distribution patterns and interspecific associations of understory herbs in the city-suburb-exurb context of Wuhan city, China

The dynamics of herb diversity, distribution patterns and interspecific associations of dominant herbs in natural forests at three growing stages in a city-suburb-exurb context in Wuhan City were studied using a fixed plot. The results show that the composition, diversity indices, mean and total richness gradually increased with the city-suburb-exurb gradient. Codominant species across temporal dynamics in Qinglong Mountain were stable, however, there were remarkable changes in the city-suburb context. Qinglong Mountain (exurb context) had the densest codominant herbs, Woodwardia japonica, Spider brake and Parathelypteris glanduligera, throughout the growing season. However, Shizi Mountain (suburb context) and Hongshan Mountain (urban context) had low-density and monodominant herbs at three stages. The overall strength of associations among herbs increased with the city-suburb-exurb context, and pairs of positive associations and significant associations (r>0.5 or r<-0.5) were more frequent on Qinglong Mountain. Therefore, the exurb-suburb-city landscape context in response to urbanization had a notable effect on the features of the understory herb layer

4,4′-Bipyridine–3-nitro­benzoic acid (1/2)

The title compound, C10H8N2·2C7H5NO4,was obtained unintentionally as the harvested product of the hydro­thermal reaction between Co(OAc)2·4H2O and 4,4′-bipyridine in the presence of 3-nitro­phthalic acid. In the reaction, 3-nitro­phthalic acid is transformed into 3-nitro­benzoic acid by an in situ deca­rboxylation reaction, in which the carboxyl­ate group is not deprotonated and is uncoordinated. In the crystal, the uncoordinated 3-nitro­benzoic acid and free 4,4′-bipyridine mol­ecules are linked alternately by O—H⋯N hydrogen bonds into chains, which are assembled by C—H⋯O hydrogen bonds into a three-dimensional supra­molecular network

Mechanism underlying synergic activation of Tyrosinase promoter by MITF and IRF4

Background: The transcription factor interferon regulatory factor 4 (IRF4) was identified to be involved in human pigmentation by genome-wide association studies (GWASs). The rs12203592-[T/C], which is located in intron 4 of IRF4, shows the strongest link to these pigmentation phenotypes including freckling, sun sensitivity, eye and hair color. Previous studies indicated a functional cooperation of IRF4 with Microphthalmia-associated transcription factor (MITF), a causing gene of Waardenburg syndrome (WS), to synergistically trans-activate Tyrosinase (TYR). However, the underlying mechanism is still unknown. Methods: To investigate the importance of DNA binding in the synergic effect of IRF4. Reporter plasmids with mutant TYR promoters was generated to locate the IRF4 DNA binding sites in the Tyrosinase minimal promoter. By building MITF and IRF4 truncated mutations plasmids, the necessary regions of the synergy functions of these two proteins were also located. Results: The cooperative effect between MITF and IRF4 was specific for TYR promoter. The DNA-binding of IRF4 was critical for the synergic function. IRF4 DNA binding sites in TYR promoter were identified. The Trans-activation domains in IRF4 (aa134-207, aa300-420) were both important for the synergic function, whereas the auto-mask domain (aa207-300) appeared to mask the synergic effect. Mutational analysis in MITF indicated that both DNA-binding and transcriptional activation domains were both required for this synergic effect. Conclusions: Here we showed that IRF4 potently synergized with MITF to activate the TYR promoter, which was dependent on DNA binding of IRF4. The synergic domains in both IRF4 and MITF were identified by mutational analysis. This identification of IRF4 as a partner for MITF in regulation of TYR may provide an important molecular function for IRF4 in the genesis of melanocytes and the pathogenic mechanism in WS