Effect of nickel chloride on Arabidopsis genomic DNA and methylation of 18S rDNA

AbstractBackgroundIn recent years, nickel (Ni) has been widely applied in industrial and agricultural production and has become a kind of environmental pollution. In this study, the effect of nickel chloride (NiCl2) with different concentrations on Arabidopsis genomic stability and DNA methylation has been demonstrated. The nucleolus variation and 18S rDNA methylation after NiCl2 treatment have been analyzed.ResultsThe results are as follows: (1) The NiCl2 could result in heritable genomic methylation variations. The genomic DNA methylation variations have been detected by methylation-sensitive amplified polymorphism (MSAP) molecular markers, and the result showed that after NiCl2 treatment, there was methylation variation in T0 generation seedlings, and partial site changes maintained in T1 generation, which suggested that the effects of NiCl2 on DNA methylation could be heritable in offspring. (2) NiCl2 brought deformity and damage to nucleolar structure in Arabidopsis root tip cells, and the damage was positively correlated with the NiCl2 concentration. 3. In the nucleolus, there was an increased cytosine methylation in 18S rDNA. The plant nucleolus variation and 18S rDNA methylation may be used as an examination indicator for Ni pollution in soil or plant.ConclusionsNiCl2 application caused variation of DNA methylation of the Arabidopsis genomic and offspring's. NiCl2 also resulted in nucleolar injury and deformity of root tip cells. The methylation rate of 18S rDNA also changed by adding NiCl2

Effect of nickel chloride on Arabidopsis genomic DNA and methylation of 18S rDNA

Background: In recent years, nickel (Ni) has beenwidely applied in industrial and agricultural production and has become a kind of environmental pollution. In this study, the effect of nickel chloride (NiCl2) with different concentrations on Arabidopsis genomic stability and DNA methylation has been demonstrated. The nucleolus variation and 18S rDNA methylation after NiCl2 treatment have been analyzed. Results: The results are as follows: (1) The NiCl2 could result in heritable genomic methylation variations. The genomic DNA methylation variations have been detected by methylation-sensitive amplified polymorphism (MSAP) molecular markers, and the result showed that after NiCl2 treatment, there was methylation variation in T0 generation seedlings, and partial site changes maintained in T1 generation, which suggested that the effects of NiCl2 on DNA methylation could be heritable in offspring. (2) NiCl2 brought deformity and damage to nucleolar structure in Arabidopsis root tip cells, and the damage was positively correlated with the NiCl2 concentration. 3. In the nucleolus, there was an increased cytosine methylation in 18S rDNA. The plant nucleolus variation and 18S rDNA methylation may be used as an examination indicator for Ni pollution in soil or plant. Conclusions: NiCl2 application caused variation of DNA methylation of the Arabidopsis genomic and offspring's. NiCl2 also resulted in nucleolar injury and deformity of root tip cells. The methylation rate of 18S rDNA also changed by adding NiCl2

A MAP Kinase Dependent Feedback Mechanism Controls Rho1 GTPase and Actin Distribution in Yeast

In the yeast Saccharomyces cerevisiae the guanosine triphosphatase (GTPase) Rho1 controls actin polarization and cell wall expansion. When cells are exposed to various environmental stresses that perturb the cell wall, Rho1 activates Pkc1, a mammalian Protein Kinase C homologue, and Mpk1, a mitogen activated protein kinase (MAPK), resulting in actin depolarization and cell wall remodeling. In this study, we demonstrate a novel feedback loop in this Rho1-mediated Pkc1-MAPK pathway that involves regulation of Rom2, the guanine nucleotide exchange factor of Rho1, by Mpk1, the end kinase of the pathway. This previously unrecognized Mpk1-depedent feedback is a critical step in regulating Rho1 function. Activation of this feedback mechanism is responsible for redistribution of Rom2 and cell wall synthesis activity from the bud to cell periphery under stress conditions. It is also required for terminating Rho1 activity toward the Pkc1-MAPK pathway and for repolarizing actin cytoskeleton and restoring growth after the stressed cells become adapted

Development and Utilization of Introgression Lines Using Synthetic Octaploid Wheat (Aegilops tauschii × Hexaploid Wheat) as Donor

As the diploid progenitor of common wheat, Aegilops tauschii Cosson (DD, 2n = 2x = 14) is considered to be a promising genetic resource for the improvement of common wheat. In this work, we demonstrated that the efficiency of transferring A. tauschii segments to common wheat was clearly improved through the use of synthetic octaploid wheat (AABBDDDD, 2n = 8x = 56) as a “bridge.” The synthetic octaploid was obtained by chromosome doubling of hybrid F1 (A. tauschii T015 × common wheat Zhoumai 18). A set of introgression lines (BC1F8) containing 6016 A. tauschii segments was developed and displayed significant phenotype variance among lines. Twelve agronomic traits, including growth duration, panicle traits, grain traits, and plant height (PH), were evaluated. And transgressive segregation was identified in partial lines. Additionally, better agronomic traits could be observed in some lines, compared to the recurrent parent Zhoumai 18. To verify that the significant variance of those agronomic traits was supposedly controlled by A. tauschii segments, 14 quantitative trait loci (QTLs) for three important agronomic traits (thousand kernel weight, spike length, and PH) were further located in the two environments (Huixian and Zhongmou), indicating the introgression of favorable alleles from A. tauschii into common wheat. This study provides an ameliorated strategy to improve common wheat utilizing a single A. tauschii genome

Exploring risk transfer of human brucellosis in the context of livestock agriculture transition: A case study in Shaanxi, China

With the booming of worldwide agriculture intensification, brucellosis, one of the most neglected zoonotic diseases, has become an increasing challenge for global public health. Although the transmission patterns of human brucellosis (HB) have been studied in many regions, the dynamic transfer processes of risk and its driving factors remain poorly understood, especially in the context of agricultural intensification. This study attempted to explore the risk transfer of HB between the exact epidemic areas and the neighboring or distant low-risk areas to explain the impact of livestock agriculture intensification and foodborne infections on the transmission of HB in Shaanxi Province as a case study. We adopted multiple approaches, including test-based methods, model-based methods, and a geographical detector to detect the spatial-temporal dynamic changes of high-risk epidemic areas of HB at the county scale. We also quantitatively estimated how the related factors drove the risk transfer of the disease. Results confirmed the risk transfer pattern of HB with an expansion from north to south in Shaanxi Province and identified two primary transfer routes. In particular, in the traditional epidemic areas of the Shaanbei plateau, the farm agglomeration effect can significantly increase the risk of HB. Meanwhile, retail outlets for milk and dairy products were partially responsible for the foodborne infections of HB in the emerging epidemic areas of Xi'an. This study not only contributed helpful insights to support HB control and prevention in the rapid transition of livestock agriculture but also provided possible directions for further research on foodborne HB infections in urbanized areas

Performance Analysis of SR-ARQ Based on Geom/G/1/¥ Queue over Wireless Link

Selective-Repeat ARQ (Automatic Repeat reQuest) protocol is the most efficient error control technology in wireless because it allows the transmitter to retransmit only negatively acknowledges (NACK) packets. In this paper, by analyzing the transmission mechanism of SR-ARQ, the discrete-time Geom/G/1/ queue model is established sententiously based on equivalent delay under the condition that the numbers of packets entering the transmitter are assumed to be independent and identically distributed random variables. With the method of embedded Markov chain, the expression formulations of the packet mean waiting delay, system mean delay and channel utilization are explicitly obtained. And then, the sliding window length control model is built adaptively according to the change of transmission conditions. Furthermore, the influences of packet length, the successful transmission probability and packet arrival rate on system mean delay are analyzed by numerical simulation. The numerical simulation results show that the expression formulations are valid for SR-ARQ protocol

Performance Analysis of SR-ARQ Based on Geom/G/1/∞ Queue over Wireless Link

because it allows the transmitter to retransmit only negatively acknowledges (NACK) packets. In this paper, by analyzing the transmission mechanism of SR-ARQ, the discrete-time Geom/G/1 / queue model is established sententiously based on equivalent delay under the condition that the numbers of packets entering the transmitter are assumed to be independent and identically distributed random variables. With the method of embedded Markov chain, the expression formulations of the packet mean waiting delay, system mean delay and channel utilization are explicitly obtained. And then, the sliding window length control model is built adaptively according to the change of transmission conditions. Furthermore, the influences of packet length, the successful transmission probability and packet arrival rate on system mean delay are analyzed by numerical simulation. The numerical simulation results show that the expression formulations are valid for SR-ARQ protocol

A Low Complexity Algorithm for Receiver Antenna Selection in MIMO Systems

For a multiple-input multiple-output (MIMO) system with more antennas at the receiver than the transmitter, selecting the same number of receiver antennas as the number of transmitter antennas can takemost of the advantages ofMIMO capacity performance and at the same time reduce the system hardware cost and computational complexity. In this paper, a novel effective low complexity near-optimal antenna selection algorithms based on maximization channel capacity is proposed for the MIMO array configuration. Different from many existing fast antenna selection algorithms which obtain the sub-optimal channel sub matrix by adding or removing one row per step exploit re-computing formula, our algorithm acquires the near-optimal channel matrix by a faster updating formula. In such faster updating formula, the formula is updating rather than re-computing, so that the matrix inverse operation is avoided. Due to using an effective iteration processing, our antenna selection algorithm reduces computational complexity and leads to a substantial improvement in the capacity optimally for moderating to high signal to noise ratio (SNRs), and obtains almost the same capacity and bit error ratio (BER) performance as that of the exhaustive-search-based optimal antenna selection algorithm. Compared to the conventional sub-optimal antenna selection algorithms, our algorithm has lower computational complexity and achieves almost the same capacity and BER performance as the optimal selection algorithm. Finally, theoretical analysis and simulation results illustrate that the new algorithm outperforms the existing sub-optimal antenna selection methods

Hybrid Cooperative Spectrum Sharing Protocols Based on OMA and NOMA in Cognitive Radio Networks

In cognitive radio networks (CRNs), the performance of the primary users (PUs) may suffer adverse effects from the secondary users (SUs) if the spectrum of PUs is haphazardly shared with SUs. In this paper, we propose a hybrid cognitive cooperative protocol based on orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) that improves spectrum utilization by allowing the SUs opportunistic access to the spectrum of the Pus, while guaranteeing the performance of the PU. Specifically, the system can switch between non-cognitive transmission mode, underlay OMA mode, and overlay OMA/NOMA mode, according to the automatic repeat request (ARQ) feedback of PU. The SU has the opportunity to acquire the spectrum to activate the underlay OMA and overlay OMA/NOMA modes only if it listens to the acknowledge (ACK) or negative acknowledge (NACK) feedback from the PU. In order to describe the switching between these three switching modes, a Markov model is developed to analyze the corresponding steady-state probabilities and end-to-end outage probabilities. So, we derive closed-form expressions for the throughput of PU and SU to investigate the spectrum utilization. Numerical and simulation results show that the proposed hybrid cooperative cognitive protocol outperforms the pure OMA hybrid cooperative cognitive protocol

Hybrid Cooperative Spectrum Sharing Protocols Based on OMA and NOMA in Cognitive Radio Networks

International audienceIn cognitive radio networks (CRNs), the performance of the primaryusers (PUs) may suffer adverse effects from the secondary users(SUs) if the spectrum of PUs is haphazardly shared with SUs. Inthis paper, we propose a hybrid cognitive cooperative protocolbased on orthogonal multiple access (OMA) and non-orthogonalmultiple access (NOMA) that improves spectrum utilization byallowing the SUs opportunistic access to the spectrum of the Pus,while guaranteeing the performance of the PU. Specifically, thesystem can switch between non-cognitive transmission mode, underlayOMA mode, and overlay OMA/NOMA mode, according to the automaticrepeat request (ARQ) feedback of PU. The SU has the opportunity toacquire the spectrum to activate the underlay OMA and overlayOMA/NOMA modes only if it listens to the acknowledge (ACK) ornegative acknowledge (NACK) feedback from the PU. In order todescribe the switching between these three switching modes, aMarkov model is developed to analyze the corresponding steady-stateprobabilities and end-to-end outage probabilities. So, we deriveclosed-form expressions for the throughput of PU and SU toinvestigate the spectrum utilization. Numerical and simulationresults show that the proposed hybrid cooperative cognitiveprotocol outperforms the pure OMA hybrid cooperative cognitiveprotocol