Open Complex Research Articles

The outcome following fixation of complex open distal femur fractures

Background: Distal femur fractures account for less than 1% of all fractures and 4%–6% of all femur fractures. Soft tissue damage, comminution and articular extension makes the treatment difficult and they often result in unsatisfactory outcome and poor knee function. Open fractures further complicate the situation. In our study we compared functional outcome, time of union and complications of open complex distal femoral fractures treated with delayed plating or primary Ilizarov ring fixator. Material and Methods: we retrospectively reviewed 23 cases presented at department of Orthopedics, from January 2011 to January 2017. All skeletally mature patients with AO type C distal femur fractures and up to Gustilo Anderson grade IIIA were included. Pathological fractures, types IIIB and IIIC open fractures and patients with other fractures in the ipsilateral limb were excluded from the study. Patients in group A were treated with delayed plating and in group B with primary Ilizarov.Result: Out of the 23 cases, all cases in both groups showed radiological union between 16-22 weeks. 3 cases of group A showed shortening of >2 cm while Ilizarov group had none. In 5 cases of group A, primary bone grafting done during surgery having severe comminution (C3 type) and in one case secondary bone grafting done after 5 months for delayed union. Out of 12 cases of group A, 5 patients (42%) achieved full flexion. In group B limited knee flexion was seen in all cases with mean flexion at final follow-up of 92°. Conclusion: Delayed fixation with autologous fibular grafting and distal femoral locking plate provides adequate restoration of knee motion and early knee mobilization with high risk of infection. Whereas Ilizarov fixator shows better outcome in terms of infection control, LLD management, lesser number of surgeries, lesser hospital stay, earlier post-op rehabilitation and acceptable knee function.

Design and Implementation of Elevator Controller using Verilog

In this cutting-edge period, lifts have turned into a basic piece of any business or open complex. It encourages the quicker development of individuals and gear between floors. The lift control framework is a standout amongst the most critical perspectives in hardware control module that are utilized as a part of car application. Normally lifts are intended for a particular building considering the fundamental factors, for example, the tallness of the building, the quantity of individuals venturing out to each floor and the normal times of high utilization. The lift framework is composed with various control procedures. This usage depends on FPGA, which can be utilized for a working with any number of floors, with the predetermined sources of info and yields. This controller can be executed for a lift with the required number of floors by just changing a control variable in the HDL code. This approach depends on a calculation which decreases the measure of calculation required, by concentrating just on the pertinent guidelines that enhances the execution of the gathering of lift framework.

INSURANCE MARKET AND SYSTEM-BASED RISK OF FUNCTIONING

The article deals with the factors and conditions for the emergence and spread of systemic risks in the insurance market within the framework of the interaction of insurance companies with each other and other financial institutions. These are forms of identifying the features of systemic risk manifestation. Focused attention is paid to factors such as competition between financial institutions, mergers and acquisitions, accumulation of individual risks, and their impact on the characteristics of the insurance market, markets of other financial intermediaries. The conditions of distribution of systemic risks — the increase of the level of capitalization of the insurance market, a separate insurance company, the presence of the transfer of risks from one to another financial intermediary.It is revealed that the possibility of diversifying the directions of formation of own assets of the insurance company determines its interaction with financial intermediaries of the stock, currency, investment market, banking services market, which causes an increase in the threat of systemic risk.The comparative characteristics of monitoring of manifestations of systemic risk on the insurance market by domestic and European financial regulators are given. The issue of insufficient attention to the degree of unevenness of the concentration of insurers’ assets in different financial markets is considered, taking into account the corresponding risks that can accumulate and exacerbate each other. The necessity of expansion of objects of monitoring by types of risks of insurance activity is established. The necessity for financial regulators to pay special attention to systemic risk is substantiated.It is proposed to assess the systemic risk in the insurance market to use a systematic approach to the diagnosis of the state of the insurance market as an open complex economic system. The main methodological principles for assessing the systemic risk of the insurance market and the individual insurance company are formulated. Concerning the specifics of the interaction of insurance companies with banking institutions, it was considered necessary to combine the risks of the insurance market and the influence of systemically important banks on the activity of a separate insurance company.

Maximizing the number of jobs scheduled at their baseline starting times in case of machine failures

We investigate the problem of keeping the maximum number of starting times of a baseline schedule if some machines happen to be out of order when the baseline schedule is to be implemented. If the machines are identical, we show that the problem is polynomially solved when no deadline is imposed on the reactive schedule and is strongly NP-hard otherwise. If the number of unrelated machines is fixed and if no deadline is imposed on the reactive schedule, a polynomial algorithm, based on a state graph, has been developed. We conclude with an open complexity question and some further research directions for this class of problems.

Structural basis for transcription activation by Crl through tethering of σS and RNA polymerase

In bacteria, a primary σ-factor associates with the core RNA polymerase (RNAP) to control most transcription initiation, while alternative σ-factors are used to coordinate expression of additional regulons in response to environmental conditions. Many alternative σ-factors are negatively regulated by anti-σ-factors. In Escherichia coli, Salmonella enterica, and many other γ-proteobacteria, the transcription factor Crl positively regulates the alternative σS-regulon by promoting the association of σS with RNAP without interacting with promoter DNA. The molecular mechanism for Crl activity is unknown. Here, we determined a single-particle cryo-electron microscopy structure of Crl-σS-RNAP in an open promoter complex with a σS-regulon promoter. In addition to previously predicted interactions between Crl and domain 2 of σS (σS2), the structure, along with p-benzoylphenylalanine cross-linking, reveals that Crl interacts with a structural element of the RNAP β'-subunit that we call the β'-clamp-toe (β'CT). Deletion of the β'CT decreases activation by Crl without affecting basal transcription, highlighting the functional importance of the Crl-β'CT interaction. We conclude that Crl activates σS-dependent transcription in part through stabilizing σS-RNAP by tethering σS2 and the β'CT. We propose that Crl, and other transcription activators that may use similar mechanisms, be designated σ-activators.

A novel comprehensive risk assessment method for sudden water accidents in the Middle Route of the South–North Water Transfer Project (China)

The Middle Route of the South–North Water Transfer Project in China consists of a long open canal and complex hydraulic structures. It provides drinking water for Beijing, Shijiazhuang, and other cities under extremely strict water quality requirements. In the recent decades, water pollution accidents have frequently occurred in water transfer projects. Scientific and effective risk assessment is needed to assess the impact on the overall emergency management, which should be considered to incorporate social, economic, and environmental issues in the timely response to and management of emergencies. In this study, we combine the Drivers–Pressures–State–Impact–Response model, fuzzy comprehensive evaluation method, and coordinated development degree model into a comprehensive risk assessment tool. This new approach was tested on an emergency drilling simulation related to a sudden MRP water pollution accident in 2016. Based on the combined integration weight ranking, “water delivery status,” “pollution accident characteristics,” “town size,” and “public satisfaction” play prominent roles in the risk assessment. Especially, “town size” is identified as the most important influent factor. The Drivers–Pressures–State–Impact–Response model index system and comprehensive risk assessment method can be used to evaluate accidents more scientifically and versatile, which helps managers or experts to make faster and more efficient decisions.

A structural mechanism for phosphorylation-dependent inactivation of the AP2 complex.

Endocytosis of transmembrane proteins is orchestrated by the AP2 clathrin adaptor complex. AP2 dwells in a closed, inactive state in the cytosol, but adopts an open, active conformation on the plasma membrane. Membrane-activated complexes are also phosphorylated, but the significance of this mark is debated. We recently proposed that NECAP negatively regulates AP2 by binding open and phosphorylated complexes (Beacham et al., 2018). Here, we report high-resolution cryo-EM structures of NECAP bound to phosphorylated AP2. The site of AP2 phosphorylation is directly coordinated by residues of the NECAP PHear domain that are predicted from genetic screens in C. elegans. Using membrane mimetics to generate conformationally open AP2, we find that a second domain of NECAP binds these complexes and cryo-EM reveals both domains of NECAP engaging closed, inactive AP2. Assays in vitro and in vivo confirm these domains cooperate to inactivate AP2. We propose that phosphorylation marks adaptors for inactivation.

Diaphyseal fractures of the forearm in adults, comparative study of dynamic compression plate versus intramedullary nail

<p class="abstract"><strong>Background:</strong> Forearm fractures are common nowadays because of road traffic accident. It is important to achieve anatomical reduction of both bone forearm fractures to regain function of upper limb. This study is undertaken to observe functional and radiological outcome using two different surgical modalities like dynamic compression plating (DCP), and intramedullary nailing in both bone forearm fractures and also to indivualize the optimal treatment method for different fracture pattern.</p><p class="abstract"><strong>Methods:</strong> Our study included 60 patients with diaphyseal forearm fractures in adults presenting to orthopaedic outpatient department. Among 60 patients, 30 patients underwent open reduction and internal fixation by dynamic compression plate and other 30 patients underwent closed reduction/open reduction by square nail after detailed pre-operative evaluation.<strong></strong></p><p class="abstract"><strong>Results:</strong> In our study average union time in DCP group is 23.39 weeks and square nail group is 28.89 weeks. Union in DCP group was 27 (90%) and square nail group 22 (73.33%). Delayed union in DCP group was 03 (10%) and in Square nail group was 6 (20%), non-union in DCP group was 0 (nil) and in square nail group was 2 (06%).</p><p class="abstract"><strong>Conclusions:</strong> Open reduction and internal fixation with DCP plates for both bone diaphyseal forearm fractures gives good results with early union rates. We also found that in open fractures and complex fracture like segmental fractures square nailing was better option compared to dynamic compression plate to reduce infection rates, retain periosteal blood supply from soft tissue. Thus we conclude that both implants are equally important and we should prioritize based on preoperative planning.</p>

Complexation of Chiral Zinc(II) Porphyrin Tweezer with Achiral Aliphatic Diamines Revisited: Molecular Dynamics, Electronic CD, and 1H NMR Analysis.

We have reported here the complexation and chiroptical behavior of the host-guest complexes using a new chiral Zn(II) bisporphyrin tweezer host and a series of achiral aliphatic diamine guests varying the chain length. (1R,2R)-Cyclohexanediamine covalently links two Zn(II) porphyrin moieties, which thereby produces a strong chiral field around the bisporphyrin tweezer framework. The chiral tweezer upon complexation with achiral guest exhibited large changes in the UV-vis spectra and CD exciton couplets due to a sudden change in the porphyrin disposition, which is controlled by the host-guest stoichiometry as well as the chain lengths of the diamine guest. Addition of smaller diamines (n: 2-5) to the host resulted in the formation of 1:1 sandwich and 1:2 open complexes, respectively, at the low and high guest concentration, which eventually display two-step inversions of the CD couplet. With longer diamines (n: 6-8), however, only 1:1 sandwich complexes are formed with retention of the CD sign. Similar observations were also reported by us recently using another chiral bisporphyrin tweezer having (1R,2R)-diphenylethylenediamine as the spacer. In an effort to obtain deeper insights into the sudden changes of interporphyrin disposition just by changing the length of the achiral diamines, we have extended a series of computational studies and correlated closely with the results obtained from the experiment. While the previously published study has relied on commonly applied Monte Carlo (MC) sampling of the potential energy surface in addition to being guided by porphyrin effective transition moment approximation, the present study uses a considerably more robust molecular modeling protocol, namely Molecular Dynamics (MD) simulations followed by full ab initio geometry optimization and TD-DFT CD prediction. The experimental data corroborate with the results obtained from the theoretical conformational analysis. The latter are also supported by experimental 1H NMR data empowered by the porphyrin ring-current effect. The NMR spectral patterns of pyrrolic protons of the free host and the 1:1 sandwich complexes appear very diagnostic and reflect the changes in the mutual porphyrin disposition on moving from the free host to the complexed ones with short and long diamines. Overall, the experimental NMR data underscore the sensitivity of pyrrolic protons chemical shifts to subtle alterations of the geometrical features, and as such, they come in agreement with the theoretically derived models.

Operators affiliated to the free shift on the Free Hardy Space

The Smirnov class for the classical Hardy space is the set of ratios of bounded analytic functions in the open complex unit disk with outer denominators. This definition extends naturally to the commutative and non-commutative multi-variable settings of the Drury-Arveson space and the full Fock space over Cd. Identifying the Fock space with the free multi-variable Hardy space of non-commutative or free holomorphic functions in a non-commutative open unit ball in several matrix-variables, we prove that any closed, densely-defined operator affiliated to the right free multiplier algebra of the full Fock space acts as right multiplication by a non-commutative function in the right free Smirnov class (and analogously, replacing ‘right’ with ‘left’).

The dormancy‐specific regulator, SutA, is intrinsically disordered and modulates transcription initiation in Pseudomonas aeruginosa

Though most bacteria in nature are nutritionally limited and grow slowly, our understanding of core processes like transcription comes largely from studies in model organisms doubling rapidly. We previously identified a small protein of unknown function, SutA, in a screen of proteins synthesized in Pseudomonas aeruginosa during dormancy. SutA binds RNA polymerase (RNAP), causing widespread changes in gene expression, including upregulation of the ribosomal RNA genes. Here, using biochemical and structural methods, we examine how SutA interacts with RNAP and the functional consequences of these interactions. We show that SutA comprises a central α-helix with unstructured N- and C-terminal tails, and binds to the β1 domain of RNAP. It activates transcription from the rrn promoter by both the housekeeping sigma factor holoenzyme (Eσ70 ) and the stress sigma factor holoenzyme (EσS ) in vitro, but has a greater impact on EσS . In both cases, SutA appears to affect intermediates in the open complex formation and its N-terminal tail is required for activation. The small magnitudes of in vitro effects are consistent with a role in maintaining activity required for homeostasis during dormancy. Our results add SutA to a growing list of transcription regulators that use their intrinsically disordered regions to remodel transcription complexes.

Quantitative assessment of the potential of retail outlets

Purpose of the study . Improving the speed and efficiency of decision-making on the development of sales of products by manufacturing companies based on the application of quantitative estimates of the potential of retail outlets, using automated methods of intellectual data analysis of Big Data. In order to create new mechanisms for the intellectual management of enterprises (economic agents) in the concept of the digital economy, it is necessary to simulate the processes of their interaction in the organizational market environment from the perspective of a multi-agent approach. The approach describes cybernetic mechanisms of interaction of agents with the ability to adapt to the needs of the population based on the analysis of market situations in order to develop intelligent management systems for enterprises to increase their market potential and competitiveness. Today the paradigm of open complex systems is used to simulate and analyze the mechanisms and processes of interaction of agents in the market environment. The main modern functioning of enterprises are corporate information systems, telecommunication networks, Internet technologies, mobile communication systems, Big Data, technologies of intellectual analysis, forecasting and machine learning. In addition, information for modeling, research and analysis of the market and the behavior of agents can be collected from open sources on the Internet. In the field of mass sales, the result of the introduction of innovative technologies is the support of decision-making in the process of managing the sales of goods and services in order to synthesize effective business-strategies for the production and sale of goods, aimed at increasing the company’s profits. From the point of view of the manufacturer, it is necessary to carry out strategic and tactical planning for the deployment and maintenance of the sales network through retail outlets that implement or have the potential to realize the company’s products. In the overwhelming majority of cases, experts make the collection and analysis of objective data on outlets, and the models for building quantitative estimates of the potential of outlets are used only the internal data on the sale of goods or partners. Materials and methods . The solution is based on the analog method of assessing the attractiveness of the outlet, used in marketing. Data mining techniques (various clustering methods) and the method of mathematical statistics - variance analysis are also used to solve this problem. Modern methods of processing large volumes of data and their intellectual analysis allow us to offer new methods for quantifying potential based on the analysis of the whole diversity of data stored in the open information sources. Results . A multi-stage method of quantitative assessment of the potential of retail outlets in ruble equivalent was proposed. A method has been developed for dividing retail outlets into strata based on features describing the position of the retail outlets, competitive environment, transport accessibility, and a typical consumer. A modification of the K-means clustering method is proposed. Conclusion . The paper proposes an approach to solving the task of promoting a wide range of products by the manufacturer through existing distribution networks. A method for quantitative assessment of the potential of outlets is proposed. The proposed method is based on the analog method of comparing outlets and uses the methods of clustering outlets across a wide range of indicators. The results of approbation of the approach on the data for 33 regions of the Russian Federation are given. The results of the work are planned to be used in the future to solve the problem of building a matrix of consumer preferences for outlets.

Simultaneous stochastic optimization of an open pit gold mining complex with supply and market uncertainty

ABSTRACTA mining complex can include multiple mines, stockpiles, waste dumps and processing facilities. Traditional optimization approaches are often based on sequential optimization of the various components in the mining complex leading to suboptimal solutions. They also do not account for uncertainty in critical inputs, resulting in misleading forecasts. This paper presents an application of a stochastic framework that simultaneously optimizes mining, destination and processing decisions for a multi-pit, multi-processor gold mining complex. The framework accounts for supply and market uncertainty via stochastic orebody and commodity price simulations as inputs to a unified optimization model. The case study notably assesses the impacts of integrating market uncertainty as input that influences all components of the production schedule. Additionally, cut-off grade decisions are determined by the simultaneous optimization process, considering material variability and operating constraints while reducing the number of a-priori decisions to be made. This approach generates solutions that capitalize on the synergies between extraction sequencing, cut-off grade optimization, blending and processing while managing and quantifying risk in strategic plans, which ultimately leads to more metal production and higher net present values.

The Experiential Benefit of an Orthopedic Trauma Fellowship: An Analysis of ACGME Case Log Data From 2006 to 2017

The Accreditation Council for Graduate Medical Education (ACGME) has published orthopedic case log data since the 2006/2007 academic year. Here, we use this data to analyze the variability in orthopedic trauma case experience reported by orthopedic trainees and to better understand the impact of an orthopedic trauma fellowship on orthopedic surgical training. Data were gathered from ACGME case log reports for orthopedic residents (reporting the cumulative case experience of graduating residents) and orthopedic trauma fellows (reporting the case experience of their fellowship year only) for all available years. The average orthopedic trauma fellow reported significantly more trauma cases in multiple body regions ("Pelvis/Hip", "Femur/Knee", and "Foot/Toes") and "Open Complex" reductions (as defined by the ACGME) in their 1 year of fellowship than the average resident reported in their 5 years of residency. On average, orthopedic trauma fellowships substantially increase the trauma case volumes of orthopedic trainees, especially with respect to lower extremity trauma.

Lateral condylar retrograde humeral nail for management of high-energy distal humeral fractures.

Distal metaphyseo-diaphyseal humeral fractures are challenging particularly if open, comminuted, or associated with nerve injury. In cases of open distal complex metaphyseo-diaphyseal humeral fractures inamenable for traditional methods of fixation, retrograde intramedullary locked humeral nail with a new lateral condylar point of entry has been proposed. Two phases of study were conducted; phase I comprised computerized tomography evaluation of right humeri of 120 adult subjects, while phase II entailed prospective analysis of 18 patients who sustained firearm injuries resulting in open distal metaphyseo-diaphyseal humeral fractures associated with radial nerve injuries. All patients were surgically managed using lateral condylar retrograde humeral nailing with primary radial nerve exploration. Distal sagittal medullary diameter of the humeral medulla was the narrowest in comparison to axial and coronal medullary diameters in phase II, which matched the results of phase I. The mean postoperative disability of the arm, shoulder, and hand score was 11.2 ± 6.4. Only five patients underwent subsequent successful tendon transfer. Lateral condylar retrograde humeral nail with early radial nerve exploration in cases of high-energy distal metaphyseo-diaphyseal humeral fractures yielded good results regarding union and spontaneous radial nerve recovery or later on reconstruction.

Can a Cl-H···F Hydrogen Bond Replace a Cl···F Halogen Bond? H2XP:ClY:ZH versus H2XP:ClY:HZ for Y, Z = F, Cl.

Ab initio MP2/aug'-cc-pVTZ (where MP2 is Møller-Plesset perturbation theory) calculations have been carried out on four series of complexes, H2XP:ClF:HCl, H2XP:ClF:HF, H2XP:ClCl:HF, and H2XP:ClCl:HCl, to answer the question raised in the title of this paper. When X is F or Cl, binary complexes containing a P(V) molecule hydrogen bonded to an acid are found on all potential surfaces except H2ClP:ClF:HF, where an ion-pair complex exists. Ion-pair complexes also result from the optimization of H2XP:ClF:HF for X = NC, CN, and H. Changing the central molecule from ClF to ClCl has a dramatic effect on the nature of the optimized complexes when the substituents are NC, CN, and H. On the potential surfaces H2XP:ClCl:FH for X = NC and CN, open ternary complexes stabilized by a pnicogen bond and a hydrogen bond are found. Optimization of H3P:ClCl:FH leads to an ion pair. For H2(NC)P:ClCl:HCl and H2(CN)P:ClCl:HCl, cyclic ternary complexes stabilized by pnicogen, halogen, and hydrogen bonds result from optimization. Optimization of H3P:ClCl:HCl leads to a reaction in which H2ClP and a second HCl molecule are formed, and the resulting cyclic ternary complex is stabilized by two hydrogen bonds and a pnicogen bond. Thus, the type of complex resulting from the optimization of the starting ternary complex H2XP:ClY:HZ depends on the nature of the central molecule ClF or ClCl, the terminal molecule HCl or HF, and the substituent X. It is not possible to simply turn around the terminal HZ molecule in complexes H2XP:ClF:ZH for Z = F and Cl to give H2XP:ClF:HZ, thereby replacing a halogen bond by a hydrogen bond. Complexes H2XP:ClCl:HZ for X = NC and CN are stable complexes, but the corresponding halogen-bonded complexes H2XP:ClCl:ZH are not.

Simulation Complexity of Open Quantum Dynamics: Connection with Tensor Networks.

The difficulty to simulate the dynamics of open quantum systems resides in their coupling to many-body reservoirs with exponentially large Hilbert space. Applying a tensor network approach in the time domain, we demonstrate that effective small reservoirs can be defined and used for modeling open quantum dynamics. The key element of our technique is the timeline reservoir network (TRN), which contains all the information on the reservoir's characteristics, in particular, the memory effects timescale. The TRN has a one-dimensional tensor network structure, which can be effectively approximated in full analogy with the matrix product approximation of spin-chain states. We derive the sufficient bond dimension in the approximated TRN with a reduced set of physical parameters: coupling strength, reservoir correlation time, minimal timescale, and the system's number of degrees of freedom interacting with the environment. The bond dimension can be viewed as a measure of the open dynamics complexity. Simulation is based on the semigroup dynamics of the system and effective reservoir of finite dimension. We provide an illustrative example showing the scope for new numerical and machine learning-based methods for open quantum systems.

Open property and complex mosaics: Variants in tenure regimes across pastoralist social-ecological systems

While it has repeatedly been observed that pastoralist resource governance systems tend not to conform to the assumptions and principles of mainstream scholarship on property rights and governance of commons, coherent theoretical reasons why this is the case are less common. One exception is the concept of open property regimes . This view holds that the quintessential features of dryland pastoralist systems—limited and highly variable rainfall, low resource density, mobility, and institutions and norms that emphasize flexibility and access—can result in pastoralist herders dynamically distributing and redistributing themselves across a territory without the assumed benefit of clear boundaries or of collective decision-making and rules. However, the open property regimes explanation describes some pastoralist systems better than others. This paper argues that some pastoralist systems are neither conventional commons nor open property regimes. Instead they tend reflect another model, referred to here as a complex mosaic regime , in which there is gradation of strength and clarity of exclusionary property rights over different resources, in which property rights are often unbundled and allocated to different actors and governance mechanisms, and in which a prominent role is played by social processes and governance mechanisms other than property rights institutions. Social and biophysical characteristics that may be more conducive to complex mosaic regimes than to open property systems, particularly if all of those characteristics are found together, include a severe and chronic shortage of one or more critical resources, spatial heterogeneity of resources, scalar heterogeneity of interests, and a herd mobility pattern that involves occasional convergence on highly valued key resource areas. In elaborating the complex mosaic regime model, this paper addresses a blind spot in scholarship on property rights and commons, deepening the understanding of why pastoralist systems tend not to conform to mainstream theory, as well as helping to explain some of the differences among pastoralist systems. Understanding the internal logic of alternative resource governance regime models and the social-ecological conditions that make one model more viable than another can help to guide national policies and the strategies of conservation and development actors.

Open complex stability regulates transcription initiation by E. coli RNA polymerase from the rrnB P1 promoter

Initiation of transcription by E. coli RNA polymerase (RNAP) begins with specific binding to promoter DNA and ends with promoter escape. For the four T7A1 and λPR promoter/discriminator combinations, we found that the discriminator determined the lifetime and stability of the open complex and the escape point of RNAP in initiation from productive promoter complexes (1). Quantitative initiation studies with these promoter/discriminator combinations reveal that the RNA‐DNA hybrid length for promoter escape and the length distribution of short (abortive) RNA released before escape both increase with the lifetime or stability of the initiation‐competent open complex (OC). The escape point for productive complexes increases from the 7‐mer to 8‐mer step for T7A1 discriminators to the 10‐mer to 11‐mer step for λPR discriminators. Nonproductive complexes make a short RNA smaller than the escape length and stall, slowly releasing it and reinitiating. These findings led us to predict that escape from a promoter like the ribosomal rrnB P1 promoter, with an unstable OC, should occur at a very short RNA‐DNA hybrid length and without release of short RNAs (1). Currently, to obtain the experimental data to test this prediction, we are performing single round transcription assays for the rrnB P1 promoter and other promoters with the rrnB P1 discriminator. In preliminary studies, we have found NTP concentrations where a significant fraction of promoters initiate rapidly. For these NTP concentrations, we find that only the shortest RNAs (e.g. 3‐mer) are made by nonproductive complexes during the time period required for productive complexes to escape and begin elongation. In addition, initiation of λPR promoter with rrnB P1 discriminator shows similar pattern comparing to initiation of rrnB P1 promoter with its own discriminator. We conclude that the current results are consistent with the proposal of early escape of RNAP from promoters with unstable OC.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The plasmid-borne quinolone resistance protein QnrB, a novel DnaA-binding protein, increases the bacterial mutation rate by triggering DNA replication stress.

SummaryBacterial antibiotic resistance, a global health threat, is caused by plasmid transfer or genetic mutations. Quinolones are important antibiotics, partially because they are fully synthetic and resistance genes are unlikely to exist in nature; nonetheless, quinolone resistance proteins have been identified. The mechanism by which plasmid‐borne quinolone resistance proteins promotes the selection of quinolone‐resistant mutants is unclear. Here, we show that QnrB increases the bacterial mutation rate. Transcriptomic and genome sequencing analyses showed that QnrB promoted gene abundance near the origin of replication (oriC). In addition, the QnrB expression level correlated with the replication origin to terminus (oriC/ter) ratio, indicating QnrB‐induced DNA replication stress. Our results also show that QnrB is a DnaA‐binding protein that may act as an activator of DNA replication initiation. Interaction of QnrB with DnaA promoted the formation of the DnaA‐oriC open complex, which leads to DNA replication over‐initiation. Our data indicate that plasmid‐borne QnrB increases bacterial mutation rates and that genetic changes can alleviate the fitness cost imposed by transmitted plasmids. Derivative mutations may impair antibiotic efficacy and threaten the value of antibiotic treatments. Enhanced understanding of how bacteria adapt to the antibiotic environment will lead to new therapeutic strategies for antibiotic‐resistant infections.