A feedback regulatory loop between methyltransferase PRMT1 and orphan receptor TR3

PRMT1, an arginine methyltransferase, plays an important role in numerous cellular processes. In this study, we demonstrate a feedback regulatory loop between PRMT1 and the orphan receptor TR3. Unlike another orphan receptor HNF4, TR3 is not methylated by PRMT1 although they physically interact with each other. By delaying the TR3 protein degradation, PRMT1 binding leads to the elevation of TR3 cellular protein level, thereby enhances the DNA binding and transactivation activity of TR3 in a non-methyltransferase manner. Another coactivator SRC-2 acts synergistically with PRMT1 to regulate TR3 functions. In turn, TR3 binding to the catalytic domain of PRMT1 causes an inhibition of the PRMT1 methyltransferase activity. This repression results in the functional changes in some of PRMT1 substrates, including STAT3 and Sam68. The negative regulation of PRMT1 by TR3 was further confirmed in both TR3-knockdown cells and TR3-knockout mice with the use of an agonist for TR3. Taken together, our study not only identifies a regulatory role of PRMT1, independent on methyltransferase activity, in TR3 transactivation, but also characterizes a novel function of TR3 in the repression of PRMT1 methyltransferase activity

Modeling and Analysis of a Compliance Model and Rotational Precision for a Class of Remote Center Compliance Mechanisms

The remote center compliance (RCC) mechanism is of great use for practical designs, especially if a pure rotation about a virtual point is required. The analysis of compliance properties and rotational precision for RCC mechanisms are very important for mechanical design in applications where precision is required. This paper formulates an analytical method for the compliance and rotational precision calculations of a class of RCC mechanisms, combined in parallel with two round beam-based isosceles-trapezoidal flexural pivots. The analytical model of the mechanism is established based on the stiffness matrix method to directly obtain the compliance factors that completely define the elastic response of the mechanism. The rotational precision of the mechanism—That is, the position of rotation center—Is then derived using screw theory and a compliance matrix. The validity of this model is demonstrated using finite element analysis simulation and experimental tests. The results of both simulation and experiment verify that the analytical model has high accuracy and promising practical applications. Moreover, the influences of the geometry parameters on the compliance factors and the center shifts are also graphically evaluated and discussed using the analytical model. The results in this paper provide an effective configuration and analytical method for the design and optimization of RCC mechanisms, and are of great practical significance

Ultrasound–Microwave Combined Extraction of Novel Polysaccharide Fractions from <i>Lycium barbarum</i> Leaves and Their In Vitro Hypoglycemic and Antioxidant Activities

Ultrasound–microwave combined extraction (UMCE), gradient ethanol precipitation, chemical characterization, and antioxidant and hypoglycemic activities of Lycium barbarum leaf polysaccharides (LLP) were systematically studied. The optimal conditions for UMCE of LLP achieved by response surface method (RSM) were as follows: microwave time of 16 min, ultrasonic time of 20 min, particle size of 100 mesh, and ratio of liquid to solid of 55:1. Three novel polysaccharide fractions (LLP30, LLP50, LLP70) with different molecular weights were obtained by gradient ethanol precipitation. Polysaccharide samples exhibited scavenging capacities against ABTS and DPPH radicals and inhibitory activities against α-glucosidase and α-amylase. Among the three fractions, LLP30 possessed relatively high antioxidant and hypoglycemic activities in vitro, which showed a potential for becoming a nutraceutical or a phytopharmaceutical for prevention and treatment of hyperglycemia or diabetes

Nitrogen Removal from Micro-Polluted Reservoir Water by Indigenous Aerobic Denitrifiers

Treatment of micro-polluted source water is receiving increasing attention because of environmental awareness on a global level. We isolated and identified aerobic denitrifying bacteria Zoogloea sp. N299, Acinetobacter sp. G107, and Acinetobacter sp. 81Y and used these to remediate samples of their native source water. We first domesticated the isolated strains in the source water, and the 48-h nitrate removal rates of strains N299, G107, and 81Y reached 33.69%, 28.28%, and 22.86%, respectively, with no nitrite accumulation. We then conducted a source-water remediation experiment and cultured the domesticated strains (each at a dry cell weight concentration of 0.4 ppm) together in a sample of source water at 20–26 °C and a dissolved oxygen concentration of 3–7 mg/L for 60 days. The nitrate concentration of the system decreased from 1.57 ± 0.02 to 0.42 ± 0.01 mg/L and that of a control system decreased from 1.63 ± 0.02 to 1.30 ± 0.01 mg/L, each with no nitrite accumulation. Total nitrogen of the bacterial system changed from 2.31 ± 0.12 to 1.09 ± 0.01 mg/L, while that of the control system changed from 2.51 ± 0.13 to 1.72 ± 0.06 mg/L. The densities of aerobic denitrification bacteria in the experimental and control systems ranged from 2.8 × 104 to 2 × 107 cfu/mL and from 7.75 × 103 to 5.5 × 105 cfu/mL, respectively. The permanganate index in the experimental and control systems decreased from 5.94 ± 0.12 to 3.10 ± 0.08 mg/L and from 6.02 ± 0.13 to 3.61 ± 0.11 mg/L, respectively, over the course of the experiment. Next, we supplemented samples of the experimental and control systems with additional bacteria or additional source water and cultivated the systems for another 35 days. The additional bacteria did little to improve the water quality. The additional source water provided supplemental carbon and brought the nitrate removal rate in the experimental system to 16.97%, while that in the control system reached only 3.01%, with no nitrite accumulation in either system. Our results show that aerobic denitrifying bacteria remain highly active after domestication and demonstrate the applicability of such organisms in the bioremediation of oligotrophic ecosystems

Molecular identification of a root apical cell-specific and stress-responsive enhancer from an Arabidopsis enhancer trap line

Abstract Background Plant root apex is the major part to direct the root growth and development by responding to various signals/cues from internal and soil environments. To study and understand root system biology particularly at a molecular and cellular level, an Arabidopsis T-DNA insertional enhancer trap line J3411 expressing reporters (GFP) only in the root tip was adopted in this study to isolate a DNA fragment. Results Using nested PCR, DNA sequencing and sequence homology search, the T-DNA insertion site(s) and its flanking genes were characterised in J3411 line. Subsequently, a 2000 bp plant DNA-fragment (Ertip1) upstream of the insert position of the coding T-DNA was in silico analysed, revealing certain putative promoter/enhancer cis-regulatory elements. Cloning and transformation of this DNA fragment and its truncated segments tagged with or without 35S minimal promoter (35Smini), all of which were fused with a GFP or GUS reporter, allowed to detect GFP and GUS expression mediated only by Ertip1 + 35mini (PErtip1+35Smini) specifically in the Arabidopsis root tip region. The PErtip1+35Smini activity was further tested to be strong and stable under many different growth conditions but suppressed by cold, salt, alkaline pH and higher ammonium and phosphorus. Conclusion This work describes a promising strategy to isolate a tissue-/cell-specific enhancer sequence from the enhancer trap lines, which are publically available. The reported synthetic promoter i.e. PErtip1+35Smini may provide a valuable and potent molecular-tool for comprehensive investigation of a gene function related to root growth and development as well as molecular engineering of root-architectural formation aiming to improve plant growth