ALBERT

Description: Aims Distyly has been regarded as an adaptation to improve compatible pollination between two floral morphs with reciprocal herkogamy. The hypothesis that the different positions of anthers and stigmas within flowers as well as their reciprocal position between morphs, reduce the probability of self pollination raised by Darwin has been rarely tested. In this study, we measured stigmatic pollen loads in response to reduced reciprocal herkogamy in two Primula species. Methods To see whether reciprocal herkogamy can increase compatible and/or reduce incompatible pollen deposition, thus promoting compatible pollination, we shortened the distance between anthers and stigmas within the flowers by changing the position of the corolla tube, to which the anthers were fused, i.e. reduced herkogamy in natural populations of Primula secundiflora and P. poissonii and quantified stigmatic pollen loads in the field over 2 years. Important Findings In both species, stigmatic pollen loads were significantly higher in the long-styled (L-morph) than in the short-styled morph (S-morph) in both control and manipulated flowers, but percentage of compatible pollen in S-morph were higher. Flowers manipulated to halve the anther–stigma distance showed a similar pattern for 2 years: total pollen grain counts on stigmas did not differ significantly but compatible pollen grains in L- and S-morphs were significantly decreased in both species. The percentage of compatible pollen loads was decreased by 68.7% in P. secundiflora and 65.3% in P. poissonii in L-morphs, while it decreased by 30.6% and 2.9% in S-morphs, respectively. Our manipulation of the relative position of anthers and stigmas in the two distylous species indicated that a lower degree of herkogamy reduced compatible but incompatible pollen transfer was likely to increase. The higher proportion of compatible pollen in the S-morph than in the L-morph in the two Primula species could be attributed to the accessibility of two-level sexual organs, floral orientations and pollinator behaviors. This is a first attempt to manipulate intraflower herkogamy for understanding adaptation of heterostyly, shedding insights into how the reciprocal herkogamy promotes compatible pollination.

Description: Dicarbonyl/ l -xylulose reductase (DCXR), mainly catalysing the reduction of α-dicarbonyl compounds and l -xylulose, belongs to the short-chain dehydrogenase/reductase superfamily. Its enzyme activity can be inhibited by short-chain fatty acids. In this study, a novel DCXR inhibitor named (–)-epigallocatechin-3-gallate (EGCG) was reported. First, we overexpressed recombinant human DCXR in Escherichia coli , purified the enzyme by affinity chromatography and measured its activity. The inhibition effects of EGCG and its analogues on DCXR were determined subsequently, and EGCG showed the strongest inhibition with 50% inhibition concentration value of 78.8 μM. The surface plasmon resonance analysis also indicated that the equilibrium dissociation constant ( K D ) reached to 7.11 x 10 –8 M, which implied a high affinity between EGCG and DCXR. From enzyme kinetic analysis, EGCG acted as a mixed inhibitor against its forward and reverse substrates and the coenzyme, reduced nicotinamide adenine dinucleotide phosphate (NADPH). However, the inhibition is pH dependent. The molecular docking finally showed that EGCG formed several hydrogen bonds with the Thr190 residue of DCXR, and the model was further verified by site-directed mutagenesis. Therefore, EGCG is a potential inhibitor to human DCXR.

Description: DNA methylation contributes to tumor formation, development and metastasis. Epigenetic dysregulation of stem cells is thought to predispose to malignant development. The clinical significance of DNA methylation in ovarian tumor-initiating cells (OTICs) remains unexplored. We analyzed the methylomic profiles of OTICs (CP70sps) and their derived progeny using a human methylation array. qRT–PCR, quantitative methylation-specific PCR (qMSP) and pyrosequencing were used to verify gene expression and DNA methylation in cancer cell lines. The methylation status of genes was validated quantitatively in cancer tissues and correlated with clinicopathological factors. ATG4A and HIST1H2BN were hypomethylated in OTICs. Methylation analysis of ATG4A and HIST1H2BN by qMSP in 168 tissue samples from patients with ovarian cancer showed that HIST1H2BN methylation was a significant and independent predictor of progression-free survival (PFS) and overall survival (OS). Multivariate Cox regression analysis showed that patients with a low level of HIST1H2BN methylation had poor PFS (hazard ratio (HR), 4.5; 95% confidence interval (CI), 1.4–14.8) and OS (HR, 4.3; 95% CI, 1.3–14.0). Hypomethylation of both ATG4A and HIST1H2BN predicted a poor PFS (HR, 1.8; 95% CI, 1.0–3.6; median, 21 months) and OS (HR, 1.7; 95% CI, 1.0–3.0; median, 40 months). In an independent cohort of ovarian tumors, hypomethylation predicted early disease recurrence (HR, 1.7; 95% CI, 1.1–2.5) and death (HR, 1.4; 95% CI, 1.0–1.9). The demonstration that expression of ATG4A in cells increased their stem properties provided an indication of its biological function. Hypomethylation of ATG4A and HIST1H2BN in OTICs predicts a poor prognosis for ovarian cancer patients.

Description: 〈span〉〈div〉SUMMARY〈/div〉Moment-tensor inversion of induced microseismic events can provide valuable information for tracking CO〈sub〉2〈/sub〉 plumes at geological carbon storage sites, and study the physical mechanism of induced microseismicity. Accurate moment-tensor inversion requires a wide-azimuthal coverage of geophones. Cost-effective microseismic monitoring for geological carbon storage often uses only one geophone array within a borehole, leading to a large uncertainty in moment-tensor inversion. We develop a new adaptive moment-tensor joint inversion method to reduce the inversion uncertainty, when using limited but typical geophone receiver geometries. We first jointly invert a number of clustered microseismic events using a uniform focal mechanism to minimize the waveform misfit between observed and predicted 〈span〉P〈/span〉 and 〈span〉S〈/span〉 waveforms. We then invert the moment tensor for each event within a limited searching range around the joint inversion result. We apply our adaptive joint inversion method to microseismic data acquired using a single borehole geophone array at the CO〈sub〉2〈/sub〉-Enhanced Oil Recovery field at Aneth, Utah. We demonstrate that our inversion method is capable of reducing the inversion uncertainty caused by the limited azimuthal coverage of geophones. Our inverted strikes of focal mechanisms of microseismic events are consistent with the event spatial distribution in subparallel pre-existing fractures or geological imperfections. The large values up to 40 per cent of the CLVD components might indicate crack opening induced by CO〈sub〉2〈/sub〉/wastewater injection or rupture complexity.〈/span〉

Description: More than 30 amyloid proteins are reported to be associated with amyloidosis diseases. Studies have implicated histidine may be critically involved in amyloid formation. Here, we used diethylpyrocarbonate (DEPC) modification to obtain a His B5 mono-ethyloxyformylated insulin (DMI-B 5 ). The secondary structure, amyloidogenicity, metal ion interaction, and cytotoxicity of DMI-B 5 and insulin were compared. DMI-B 5 was less prone to aggregation in acidic condition but easier to aggregate at neutral pH. DEPC modification resulted in attenuated inhibitory effect of Zn 2+ on aggregation, whereas DMI-B 5 fibrils induced more severe erythrocytes haemolysis compared to insulin fibrils. This study not only provides a fast new approach for studying the impact of imidazole ring in amyloid formation, but also reveals the critical modulating role of histidine imidazole ring on the amyloidogenicity of insulin.

Description: 〈span〉〈div〉Summary〈/div〉Moment-tensor inversion of induced microseismic events can provide valuable information for tracking CO〈sub〉2〈/sub〉 plumes at geologic carbon storage sites, and study the physical mechanism of induced microseismicity. Accurate moment-tensor inversion requires a wide-azimuthal coverage of geophones. Cost-effective microseismic monitoring for geologic carbon storage often uses only one geophone array within a borehole, leading to a large uncertainty in moment-tensor inversion. We develop a new adaptive moment-tensor joint inversion method to reduce the inversion uncertainty, when using limited but typical geophone receiver geometries. We first jointly invert a number of clustered microseismic events using a uniform focal mechanism to minimize the waveform misfit between observed and predicted P- and S-waveforms. We then invert the moment tensor for each event within a limited searching range around the joint inversion result. We apply our adaptive joint inversion method to microseismic data acquired using a single borehole geophone array at the CO〈sub〉2〈/sub〉-Enhanced Oil Recovery field at Aneth, Utah. We demonstrate that our inversion method is capable of reducing the inversion uncertainty caused by the limited azimuthal coverage of geophones. Our inverted strikes of focal mechanisms of microseismic events are consistent with the event spatial distribution in subparallel pre-existing fractures or geologic imperfections. The large values up to 40 per cent of the CLVD components might indicate crack opening induced by CO〈sub〉2〈/sub〉/wastewater injection or rupture complexity.〈/span〉

Description: Quantifying time-lapse changes of subsurface geophysical properties is crucial for many applications, such as monitoring for oil/gas production, for geologic carbon storage, and for enhanced geothermal systems, etc. We develop a new double-difference acoustic-waveform inversion method and a new double-difference elastic-waveform inversion method using a modified total-variation regularization scheme for accurate estimation of subsurface geophysical properties changes. The method jointly inverts time-lapse seismic data for changes of geophysical properties in target monitoring regions. Our new waveform inversion algorithms incorporate a modified total-variation regularization scheme consisting of two regularization terms: an L 2  norm term and an L 1  norm total-variation term. We employ an alternating minimization method to decouple our new waveform inversion with the modified total-variation regularization into two minimization subproblems to improve the robustness of waveform inversion. We use seismic-waveform inversion with a modified total-variation regularization scheme to produce an accurate baseline geophysical model using the baseline seismic data and apply our new double-difference seismic-waveform inversion to time-lapse seismic data to quantify time-lapse changes of geophysical properties. Our new double-difference waveform inversion algorithm not only preserves sharp interfaces of the target monitoring regions but also reduces inversion artefacts outside the target monitoring regions. We use synthetic time-lapse seismic data to validate the improvement of our new methods. Our numerical results show that our new double-difference acoustic- and elastic-waveform inversion methods significantly improve the accuracy of time-lapse seismic data inversion compared to other inversion methods.