New isoforms and assembly of glutamine synthetase in the leaf of wheat (Triticum aestivum L.).

Glutamine synthetase (GS; EC 6.3.1.2) plays a crucial role in the assimilation and re-assimilation of ammonia derived from a wide variety of metabolic processes during plant growth and development. Here, three developmentally regulated isoforms of GS holoenzyme in the leaf of wheat (Triticum aestivum L.) seedlings are described using native-PAGE with a transferase activity assay. The isoforms showed different mobilities in gels, with GSII>GSIII>GSI. The cytosolic GSI was composed of three subunits, GS1, GSr1, and GSr2, with the same molecular weight (39.2kDa), but different pI values. GSI appeared at leaf emergence and was active throughout the leaf lifespan. GSII and GSIII, both located in the chloroplast, were each composed of a single 42.1kDa subunit with different pI values. GSII was active mainly in green leaves, while GSIII showed brief but higher activity in green leaves grown under field conditions. LC-MS/MS experiments revealed that GSII and GSIII have the same amino acid sequence, but GSII has more modification sites. With a modified blue native electrophoresis (BNE) technique and in-gel catalytic activity analysis, only two GS isoforms were observed: one cytosolic and one chloroplastic. Mass calibrations on BNE gels showed that the cytosolic GS1 holoenzyme was ~490kDa and likely a dodecamer, and the chloroplastic GS2 holoenzyme was ~240kDa and likely a hexamer. Our experimental data suggest that the activity of GS isoforms in wheat is regulated by subcellular localization, assembly, and modification to achieve their roles during plant development

Domain Ontology Construction in the Glioma

Objective To construct a domain ontology for glioma, and to achieve knowledge sharing and reasoning in the field of glioma through reuse and sharing of knowledge. Methods A domain ontology for glioma was constructed using the Ontology Web Language as the description language and a seven-step approach with the help of the ontology construction tool Protégé 5.5.0 as a knowledge source. Results A more comprehensive knowledge system related to glioma was presented, with 35 classes, 85 instances, 8 object properties and 5 data properties constructed. Conclusion By integrating the glioma knowledge and establishing the corresponding domain ontology, it provides knowledge support and reasoning basis for sharing, reusing and building the knowledge base of glioma knowledge

Reorientation of cortical microtubule arrays in the hypocotyl of arabidopsis thaliana is induced by the cell growth process and independent of auxin signaling

Cortical microtubule arrays in elongating epidermal cells in both the root and stem of plants have the propensity of dynamic reorientations that are correlated with the activation or inhibition of growth. Factors regulating plant growth, among them the hormone auxin, have been recognized as regulators of microtubule array orientations. Some previous work in the field has aimed at elucidating the causal relationship between cell growth, the signaling of auxin or other growth-regulating factors, and microtubule array reorientations, with various conclusions. Here, we revisit this problem of causality with a comprehensive set of experiments in Arabidopsis thaliana, using the now available pharmacological and genetic tools. We use isolated, auxin-depleted hypocotyls, an experimental system allowing for full control of both growth and auxin signaling. We demonstrate that reorientation of microtubules is not directly triggered by an auxin signal during growth activation. Instead, reorientation is triggered by the activation of the growth process itself and is auxin-independent in its nature. We discuss these findings in the context of previous relevant work, including that on the mechanical regulation of microtubule array orientation

Ambient Air Pollution as a Mediator in the Pathway Linking Race/Ethnicity to Hypertension: the Multi-Ethnic Study of Atherosclerosis (MESA)

Background: Racial/ethnic disparities in blood pressure and hypertension have been evident in previous studies, as were associations between race/ethnicity with ambient air pollution and those between air pollution with hypertension, which suggests that air pollution may have mediating effects linking race/ethnicity to hypertension. Objective: To assess the potential mediating effects of ambient air pollution on the association between race/ethnicity and blood pressure/hypertension. Methods: We studied 6,463 White, Black, Hispanic and Chinese adults enrolled between 2000 and 2002 across 6 US cities. Systolic (SBP) and diastolic blood pressure (DBP) were measured at Exam 1 (2000-2002) and Exam 2 (2002-2004). Household-level annual average concentrations of fine particulate matter (PM2.5), oxides of nitrogen (NOX), and ozone(O3) for the year 2000 were estimated for participants. Results: The difference in SBP levels by race/ethnicity that was related to higher PM2.5 concentrations compared with White men (“indirect associations”) was 0.3 (95% CI: 0.1, 0.5) mmHg for Black men, 0.3 (95% CI: 0.1, 0.6) mmHg for Hispanic men and 1.0 (95% CI: 0.2, 1.8) mmHg for Chinese men. Findings were similar although not statistically significant for women. PM2.5 did not mediate racial/ethnic differences in DBP. Indirect associations were significant for ozone for both SBP and DBP among men and women. In contrast, racial/ethnic disparities were attenuated due to exposure to NOX. Associations with blood pressure levels were stronger among participants with hypertension. Among the 3,089 participants without hypertension at baseline, 422 developed incident hypertension. For racial/ethnic disparities in incident hypertension, only indirect associations for ozone among men were marginally significant. Conclusion: Racial disparities in blood pressure were reduced after accounting for PM2.5 and ozone while increased after accounting for NOX, but mediating effects of air pollution on the pathway linking race/ethnicity to incident hypertension were barely found

Numerical approaches for the rapid analysis of prophylactic efficacy against HIV with arbitrary drug-dosing schemes

Pre-exposure prophylaxis (PrEP) is an important pillar to prevent HIV transmission. Because of experimental and clinical shortcomings, mathematical models that integrate pharmacological, viral- and host factors are frequently used to quantify clinical efficacy of PrEP. Stochastic simulations of these models provides sample statistics from which the clin- ical efficacy is approximated. However, many stochastic simulations are needed to reduce the associated sampling error. To remedy the shortcomings of stochastic simulation, we developed a numerical method that allows predicting the efficacy of arbitrary prophylactic regimen directly from a viral dynamics model, without sampling. We apply the method to var- ious hypothetical dolutegravir (DTG) prophylaxis scenarios. The approach is verified against state-of-the-art stochastic simulation. While the method is more accurate than stochastic simulation, it is superior in terms of computational performance. For example, a continuous 6-month prophylactic profile is computed within a few seconds on a laptop computer. The method’s computational performance, therefore, substantially expands the horizon of feasi- ble analysis in the context of PrEP, and possibly other applications.Pre-exposure prophylaxis (PrEP) is an important tool to prevent HIV transmission. However, experimental identification of parameters that determine prophylactic efficacy is extremely difficult. Clues about these parameters could prove essential for the design of next-generation PrEP compounds. Integrative mathematical models can fill this void: Based on stochastic simulation, a sample statistic can be generated, from which the prophylactic efficacy is estimated. However, for this sample statistic to be accurate, many simulations need to be performed. Here, we introduce a numerical method to directly compute the prophylactic efficacy from a viral dynamics model, without the need for sampling. Based on several examples with dolutegravir (DTG) -based short- and long-term PrEP, as well as post-exposure prophylaxis we demonstrate the correctness of the new method and its outstanding computational performance. Due to the method’s computational performance, a number of analyses, including formal sensitivity analysis, are becoming feasible with the proposed method.Peer Reviewe

Real-time analysis of auxin response, cell wall pH and elongation in Arabidopsis thaliana Hypocotyls

The rapid auxin-triggered growth of the Arabidopsis hypocotyls involves the nuclear TIR1/AFB-Aux/IAA signaling and is accompanied by acidification of the apoplast and cell walls (Fendrych et al., 2016). Here, we describe in detail the method for analysis of the elongation and the TIR1/AFB-Aux/IAA-dependent auxin response in hypocotyl segments as well as the determination of relative values of the cell wall pH