Electromagnetic and gravitational radiation from the coherent oscillation of electron-positron pairs and fields

Integrating equations of particle-number and energy-momentum conservation and Maxwell field equations, we study the oscillation and drift of electron and positron pairs coherently with fields after these pairs are produced in external electromagnetic fields. From the electric current of oscillating pairs, we obtain the energy spectrum of electromagnetic dipole radiation. This narrow spectrum is so peculiar that the detection of such radiation can identify pair production and oscillation in strong laser fields. We also obtain the energy spectrum of gravitational quadrapole radiation from the energy-momentum tensor of oscillating pairs and fields. Thus, we discuss the generation of gravitational waves on the basis of rapid development of strong laser fields.Comment: 6 pages, 4 figure

Reverse gyrase functions in genome integrity maintenance by protecting DNA breaks in vivo

Reverse gyrase introduces positive supercoils to circular DNA and is implicated in genome stability maintenance in thermophiles. The extremely thermophilic crenarchaeon Sulfolobus encodes two reverse gyrase proteins, TopR1 (topoisomerase reverse gyrase 1) and TopR2, whose functions in thermophilic life remain to be demonstrated. Here, we investigated the roles of TopR1 in genome stability maintenance in S. islandicus in response to the treatment of methyl methanesulfonate (MMS), a DNA alkylation agent. Lethal MMS treatment induced two successive events: massive chromosomal DNA backbone breakage and subsequent DNA degradation. The former occurred immediately after drug treatment, leading to chromosomal DNA degradation that concurred with TopR1 degradation, followed by chromatin protein degradation and DNA-less cell formation. To gain a further insight into TopR1 function, the expression of the enzyme was reduced in S. islandicus cells using a CRISPR-mediated mRNA interference approach (CRISPRi) in which topR1 mRNAs were targeted for degradation by endogenous III-B CRISPR-Cas systems. We found that the TopR1 level was reduced in the S. islandicus CRISPRi cells and that the cells underwent accelerated genomic DNA degradation during MMS treatment, accompanied by a higher rate of cell death. Taken together, these results indicate that TopR1 probably facilitates genome integrity maintenance by protecting DNA breaks from thermo-degradation in vivo

Nanobiomotors of archaeal DNA repair machineries:current research status and application potential

Nanobiomotors perform various important functions in the cell, and they also emerge as potential vehicle for drug delivery. These proteins employ conserved ATPase domains to convert chemical energy to mechanical work and motion. Several archaeal nucleic acid nanobiomotors, such as DNA helicases that unwind double-stranded DNA molecules during DNA damage repair, have been characterized in details. XPB, XPD and Hjm are SF2 family helicases, each of which employs two ATPase domains for ATP binding and hydrolysis to drive DNA unwinding. They also carry additional specific domains for substrate binding and regulation. Another helicase, HerA, forms a hexameric ring that may act as a DNA-pumping enzyme at the end processing of double-stranded DNA breaks. Common for all these nanobiomotors is that they contain ATPase domain that adopts RecA fold structure. This structure is characteristic for RecA/RadA family proteins and has been studied in great details. Here we review the structural analyses of these archaeal nucleic acid biomotors and the molecular mechanisms of how ATP binding and hydrolysis promote the conformation change that drives mechanical motion. The application potential of archaeal nanobiomotors in drug delivery has been discussed

Using VBIM technique to identify novel carboplatin resistance gene in ovarian cancer

poster abstractOvarian cancer (OC) is the most lethal gynecology cancer in the world. Although carboplatin is one of the major drugs used to treat OC, resistance to carboplatin remains a major barrier to successful treatment. To date, the mechanisms of carboplatin resistance are still poorly understood. The purpose of this study is to use the novel validation-based insertional mutagenesis (VBIM) technique to identify carboplatin resistance gene in A2780 OC cells. A2780 cells were infected with VBIM virus to cause the overexpression of drug resistance genes, then were further selected under carboplatin treatment. Targeted gene was then identified by using VBIM specific primers. In a preliminary screen, we identified the novel carboplatin resistance gene 1 (NCR1). Overexpression of NCR1 increased carboplatin resistance in A2780 OC cells, while knocking it down with shRNA had the opposite effect. In an attempt to investigate the molecular mechanism that underlying NCR1-mediated carboplatin resistance, we found that NCR1 is a potential NF- B activator. In summary, we conclude that using a novel VBIM technique, we discovered a previously unknown carboplatin resistance gene NCR1, which may mediate drug resistance via NF-B signaling pathway. This study is of extreme importance by identifying a potential novel therapeutic target NCR1 in carboplatin resistance. Development of small chemical inhibitors targeting NCR1 could ultimately lead to novel therapeutic approach for ovarian cancer treatment

Revisiting Michael Bonell's work on humid tropical rainforest catchments: Isotope tracers reveal seasonal shifts in catchment hydrology

It has been almost 50 years since the foundational work at the Babinda catchments in North Queensland kickstarted the field of tropical hydrology globally. To expand upon this work and build a more generalized hydrological understanding of steep rainforest catchments, we studied the seasonal evolution of hydrological response from two catchments with broadly similar characteristics to the Babinda catchments. Both hydrometric and water stable isotope data were collected at relatively high frequencies during one wet season (Thompson Creek) and a 3-year period (Atika Creek). The longer dataset spans a wide range of environmental conditions experienced in the humid tropics, including events that cover the wetting-up transitional period of the wet season and tropical cyclones (TC). Both catchments displayed a fast streamflow response to rainfall with the shallow upper soil profile responding quickly to rainfall at Atika Creek. New findings from this study include the importance of pre-event water (>50% using the two component hydrograph separation technique) for overall event flows, especially when the catchment was wet. Rainfall, surface runoff and groundwater isotope and specific electrical conductivity (SEC) compositions varied between rainfall events with the most complex bivariate mixing plots observed for multi-peak events that occurred at the start of the wet season and after a dry period within the wet season. Two-tracer, 3 component hydrograph separations did not provide satisfactory results in identifying source water contributions to streamflow. These results highlighted the time-variant and non-conservative behaviour of the rainfall, surface runoff and shallow groundwater source waters over the seasonal timescale, with soil water being an important unidentified source contributor. Our findings highlight the need for high frequency multi-source sampling to accurately interpret catchment behaviour and the importance of soil water contributions to streamflow. We propose a framework to describe the seasonal evolution of streamflow response in steep tropical rainforest catchments experiencing seasonal rainfall activity

Development of the Risk Management Mechanism of an Enterprise Resource Planning System based on Work System Method

This study collects 24 risk-management-relevant research papers published between 2000 and 2010 to elicit significant risk factors and thus develop the risk management mechanism of an enterprise resource planning (ERP) system. The study adopts the grounded theory and conducts an expert questionnaire in order to report its findings on 49 risk factors. Based on the work system method, the identified factors are classified into nine categories and a risk management mechanism is developed thereafter. Finally, to examine the feasibility of the mechanism, two case studies are further investigated. The developed mechanism is found to be a convenient, quick, and proper ERP system risk management tool that can assist enterprises in identifying, analyzing, assessing, and responding to potential risks