Bacterial usage of the cyclic dinucleotide c‐di‐GMP is widespread, governing the transition between motile/sessile and unicellular/multicellular behaviors. There is limited information on c‐di‐GMP ...metabolism, particularly on regulatory mechanisms governing control of EAL c‐di‐GMP phosphodiesterases. Herein, we provide high‐resolution structures for an EAL enzyme Bd1971, from the predatory bacterium Bdellovibrio bacteriovorus, which is controlled by a second signaling nucleotide, cAMP. The full‐length cAMP‐bound form reveals the sensory N‐terminus to be a domain‐swapped variant of the cNMP/CRP family, which in the cAMP‐activated state holds the C‐terminal EAL enzyme in a phosphodiesterase‐active conformation. Using a truncation mutant, we trap both a half‐occupied and inactive apo‐form of the protein, demonstrating a series of conformational changes that alter juxtaposition of the sensory domains. We show that Bd1971 interacts with several GGDEF proteins (c‐di‐GMP producers), but mutants of Bd1971 do not share the discrete phenotypes of GGDEF mutants, instead having an elevated level of c‐di‐GMP, suggesting that the role of Bd1971 is to moderate these levels, allowing “action potentials” to be generated by each GGDEF protein to effect their specific functions.
Synopsis
The cyclic‐di‐GMP hydrolase Bd1971 is a sensor‐enzyme fusion protein controlling turnover and predatory behavior of the bacterium Bdellovibrio bacteriovorus. Here, structural work combined with enzyme assays and genetics reveal regulation of Bd1971 by cAMP, with important consequences for signalling during the Bdellovibrio lifecycle.
The Bd1971 structure identifies a sensor adapted from the dimeric CRP superfamily.
Bd1971 bound to stimulus cAMP renders the protein active to hydrolyse cyclic‐di‐GMP.
Empty and part‐occupied sensor structures reveal a “swing‐out” mechanism of regulation.
Bd1971 can bind GGDEF synthases and putatively allow “action potential” spikes of cyclic‐di‐GMP to be generated.
Structural and biochemical work shows how usage of the second messenger cyclic dinucleotide c‐di‐GMP is controlled by upstream cAMP.
In the current exhibition industry, it is crucial for organizers and exhibitors to comprehend and enhance visitor experiences. The objective of this study is to improve the exhibition setting by ...utilizing Near Field Communication (NFC) technology to capture, monitor, and analyze visitor behavior, engagement, and satisfaction. The main approach entails combining NFC technology with the Visitor Experience Map to fully understand the complexities of the visitor experience. NFC-enabled smartphones facilitate seamless interaction with the system, as users simply need to bring their smartphones close to NFC tags. This enables data collection and triggers the activation of a visitor scoring form for ratings and feedback. The study's findings indicate a mean system usability score of 81.4, which demonstrates successful implementation and great usability. This confirms the effective and easy-to-use nature of the strategy, guaranteeing that visitors can effortlessly provide their ratings and feedback. The originality and enhancement reside in the successful integration of NFC technology with the Visitor Experience Map, providing a strong and user-focused approach for organizers and exhibitors to enhance the exhibition experience. This study creates a favorable situation for both visitors and stakeholders, demonstrating the potential of technological advancements to greatly influence the exhibition industry. Doi: 10.28991/ESJ-2024-08-01-015 Full Text: PDF
After publication of this supplement abstract article 1, some errors in the published version 1 were reported and are included in this erratum. Abstract PM4 was accidentally withdrawn during the ...processing of the supplement when it should not have been. The Publisher apologises for this error and inconveniences caused. PM4 has been included in full this erratum. In the abstract AR11, “3 MRGN” and “4 MRGN” were incorrectly included as “MGRN” in the ‘Material and methods’ section. This has been corrected in the abstract in this erratum. In abstract AR12, “95% CI” was incorrectly referred to as “95% C.I”. A point should not have been included between “C” and “I”. This has been corrected in the abstract included in this erratum. In abstract E6, “aims“ was incorrectly indicated as “aim” and "of the study is" should not have been included in the ‘Background’ section. These have been corrected in the abstract in this erratum. In the abstract PM1, “Kirby-Bauer” was incorrectly referred to as “Kirby-bauer” in the ‘Materials and methods’ section. The correct presentation of this is included in the abstract in this erratum. In abstract PM6, “pathogens” and “vancomycin” were capitalised incorrectly in the ‘Background’ and ‘Materials and methods’ section. These have been corrected in the abstract in this erratum. In abstract PM12, Nattawipa Boonkirdram’s Family Name was incorrectly presented as “boon kirdram”. This has been corrected in the abstract in this erratum. In abstract P27, “coagulase-negative staphylococci” was incorrectly italicised. This has been corrected in the abstract in this erratum.
In this paper, we consider a crew scheduling problem (CSP) of bus transportation with the objective of minimizing the cost of crew members. We address a different time frame and different type of ...crew members. The maximum total working limit for each type of crew member has been set. The problem can be formulated as a Tactical Fixed Task Scheduling Problem (TFTSP) where the ready time and due date of the tasks are fixed in advance. A Binary Linear Programming (BLP) model is used to obtain an optimal solution for the problem. We conduct a testing and implement the model using LINGO 17.0 software. Results of the computational testing give optimum values for the problem. Hence, a feasible crew scheduling is obtained.
In the Main Memory Database (MMDB), the primary copy of the database resides in volatile main memory. This makes the MMDB more vulnerable to failures compared to Disk Resident Database (DRDB). A ...backup copy of the database is maintained in secondary storage for recovery purposes. Recovery activities like logging, check pointing and reloading are used to restore the database to a consistent state after system failure. In this paper, a recovery scheme using two page replacement algorithms for MMDB was implemented. The performance of the recovery mechanism as a function of the number of pages and size of pages was measured. From the results, the recovery time increase almost linearly with the increase in the size of the memory and that the number of pages in the memory affects the recovery. The simulation results show that the Least Recently Used (LRU) algorithm will have the least recovery time compared to First-in First-out (FIFO) algorithm. These techniques can be utilized for replacement of the lost memory to improve the recovery time and can be further enhanced to other areas of web caching.
Honey is characterized as a natural and raw foodstuff that can be consumed not only as a sweetener but also as medicine due to its therapeutic impact on human health. It is prone to adulterants ...caused by humans that manipulate the quality of honey. Although honey consumption has remarkably increased in the last few years all around the world, the safety of honey is not assessed and monitored regularly. Since the number of consumers of honey adulteration have increased in recent years, their trust and interest in this valuable product has decreased. Honey adulterants are any substances that are added to the pure honey. In this regard, this paper provides a comprehensive and critical review of the different types of adulteration, common sugar adulterants and detection methods, and draws a clear perspective toward the impact of honey adulteration on human health. Adulteration increases the consumer's blood sugar, which can cause diabetes, abdominal weight gain, and obesity, raise the level of blood lipids and can cause high blood pressure. The most common organ affected by honey adulterants is the liver followed by the kidney, heart, and brain, as shown in several in vivo research designs.
The significance of creativity and performance in the workplace has been illustrated on various occasions. This study aims to find out if there is a link between transformative leadership, ...organizational innovation, psychological issues such as hindrance and challenge stressors, and employee creativity and employee performance. There is still a lack of awareness of the factors that influence employee performance in small and medium businesses (SMEs) in Pakistan. Pakistan's SMEs have struggled to survive in their early years, with an initial failure rate of 90 percent to 95 percent.
The relationship between hindrance and challenge stressors, organizational innovation, transformational leadership, employee creativity, and their effect on overall employee performance is established through employing Structural Equation Modeling (SEM). In this study, constructs were developed from existing theories, hypotheses were generated, data were collected from 424 SME employees, and SEM analysis was conducted to prove the suggested hypothesis. The employees of SMEs are the research study's unit of analysis.
The findings of this study demonstrated that challenge stressors, transformational leadership, and employee creativity all had positive and significant effects on employee performance.
This is one of the first studies to study and extends existing understanding of psychological research in this manner and following correlations in a developing country, Pakistan: the links between transformational leadership and employees' perception of creativity and performance along with organizational innovation and work stressors. Based on theoretical considerations, a model is proposed, and hypotheses are established and explored. The findings of this study can help businesses increase employee performance by informing employee performance improvement methods. Business executives might learn more about how to engage and motivate employees to improve their performance.
Since ancient times, honey has been used for medical purposes and the treatment of various disorders. As a high-quality food product, the honey industry is prone to fraud and adulteration. Moreover, ...limited experimental studies have investigated the impact of adulterated honey consumption using zebrafish as the animal model. The aims of this study were: (1) to calculate the lethal concentration (LC50) of acid-adulterated Apis mellifera honey on embryos, (2) to investigate the effect of pure and acid-adulterated A. mellifera honey on hatching rate (%) and heart rate of zebrafish (embryos and larvae), (3) to elucidate toxicology of selected adulterated honey based on lethal dose (LD50) using adult zebrafish and (4) to screen the metabolites profile of adulterated honey from blood serum of adult zebrafish. The result indicated the LC50 of 31.10 ± 1.63 (mg/ml) for pure A. mellifera honey, while acetic acid demonstrates the lowest LC50 (4.98 ± 0.06 mg/ml) among acid adulterants with the highest mortality rate at 96 hpf. The treatment of zebrafish embryos with adulterated A. mellifera honey significantly (p ≤ 0.05) increased the hatching rate (%) and decreased the heartbeat rate. Acute, prolong-acute, and sub-acute toxicology tests on adult zebrafish were conducted at a concentration of 7% w/w of acid adulterants. Furthermore, the blood serum metabolite profile of adulterated-honey-treated zebrafish was screened by LC-MS/MS analysis and three endogenous metabolites have been revealed: (1) Xanthotoxol or 8-Hydroxypsoralen, (2) 16-Oxoandrostenediol, and (3) 3,5-Dicaffeoyl-4-succinoylquinic acid. These results prove that employed honey adulterants cause mortality that contributes to higher toxicity. Moreover, this study introduces the zebrafish toxicity test as a new promising standard technique for the potential toxicity assessment of acid-adulterated honey in this study and hazardous food adulterants for future studies.
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•Embryotoxicity of pure and acid-adulterated Apis mellifera honey.•Lethal concentration and dose, hatching and heartbeat rate of pure and acid-adulterated Apis mellifera honey was evaluated.•Toxic endogenous metabolites were identified using LCMS/MS analysis.
Aptamers are short single-stranded oligonucleotides (either DNA or RNA) that can fold into well-defined three-dimensional (3D) spatial structures which enable them to capture their specific target by ...complementary shape interactions. Aptamers are selected from large random libraries through the SELEX process and only a small fraction of the sequence is involved in direct docking with the target. In this paper, we describe the possible truncation variants of zearalenone (ZEA) aptamer which might be an effective binding region for the target. The originally selected zearalenone (ZEA) aptamer was 80-mer in length and shown to bind the target with a high affinity (
K
d
= 41 ± 5 nM). Herein, computational docking simulation was performed with 15 truncated variants to determine the predicted binding energy and responsible binding site of the aptamer-analyte complex. The results revealed that 5 truncated variants had binding energy lower than − 7.0 kcal/mol. Circular dichroism analysis was performed on the shortlisted aptamer and the conformational change of aptamers was observed with the presence of an analyte. Aptamer Z3IN (29-mer) was chosen as the most enhanced affinity for its target with a dissociation constant of 11.77 ± 1.44 nM. The aptamer was further applied in the electrochemical aptasensor of ZEA based on an indirect competitive format. The results demonstrated that the truncated aptamer leads to an enhancement of the sensitivity of the biosensor.
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