Coordination of carbon partitioning and photosynthesis by a two-component signaling network in Synechococcus elongatus PCC 7942.

Photosynthetic organisms need to balance the rate of photosynthesis with the utilization of photosynthetic products by downstream reactions. While such "source/sink" pathways are well-interrogated in plants, analogous regulatory systems are unknown or poorly studied in single-celled algal and cyanobacterial species. Towards the identification of energy/sugar sensors in cyanobacteria, we utilized an engineered strain of Synechococcus elongatus PCC 7942 that allows experimental manipulation of carbon status. We conducted a screening of all two-component systems (TCS) and serine/threonine kinases (STKs) encoded in S. elongatus PCC 7942 by analyzing phenotypes consistent with sucrose-induced relaxation of sink inhibition. We narrowed the candidate sensor proteins by analyzing changes observed after sucrose feeding. We show that a clustered TCS network containing RpaA, CikB, ManS and NblS are involved in the regulation of genes related to photosynthesis, pigment synthesis, and Rubisco concentration in response to sucrose. Altogether, these results highlight a regulatory TCS group that may play under-appreciated functions in carbon partitioning and energy balancing in cyanobacteria.

Application of molecular epidemiology in revealing HIV-1 transmission network and recombination patterns in Tianjin, China.

Using a comprehensive molecular epidemiological approach, we characterized the transmission dynamics of HIV-1 among the MSM population in Tianjin, China. Our findings revealed that 38.56% (386/1001) of individuals clustered across 109 molecular transmission clusters (TCs), with MSM aged 50 and below being the group most commonly transmitting HIV-1. Among the identified TCs, CRF01_AE predominated, followed by CRF07_BC. Notably, CRF07_BC demonstrated a higher propensity for forming large clusters compared to CRF01_AE. Birth-death skyline analyses of the two largest clusters indicated that the HIV/AIDS transmission may be at a critical point, nearly all had Re approximately 1 by now. A retrospective analysis revealed that the rapid expansion of these large clusters was primarily driven by the introduction of viruses in 2021, highlighting the crucial importance of continuous molecular surveillance in identifying newly emerging high-risk transmission chains and adapting measures to address evolving epidemic dynamics. Furthermore, we detected the transmission of drug-resistant mutations (DRMs) within the TCs, particularly in the CRF07_BC clusters (K103N, Y181C, and K101E) and CRF01_AE clusters (P225H and K219R), emphasizing the importance of monitoring to support the continued efficacy of first-line therapies and pre-exposure prophylaxis (PrEP). Recombination analyses indicated that complex recombinant patterns, associated with increased amino acid variability, could confer adaptive traits to the viruses, potentially providing a competitive advantage in certain host populations or regions. Our study highlights the potential of integrating molecular epidemiological and phylodynamic approaches to inform targeted interventions.

Tailoring CuOx loading on CoFe2O4 nanocubes photocatalyst for superior photocatalytic degradation of triclosan pollutants under VL irradiation and toxicological evaluation.

In this study, we report the development of a novel CuOx(3 wt%)/CoFe2O4 nanocubes (NCs) photocatalyst through simple co-precipitation and wet impregnation methods for the efficient photocatalytic degradation of triclosan (TCS) pollutants. Initially, rod-shaped bare CoFe2O4 was synthesized using a simple co-precipitation technique. Subsequently, CuOx was loaded in various percentages (1, 2, and 3 wt%) onto the surface of bare CoFe2O4 nanorods (NRs) via the wet impregnation method. The synthesized materials were systematically characterized to evaluate their composition, structural and electrical characteristics. The CuOx(3 wt%)/CoFe2O4 NCs photocatalyst exhibited superior photocatalytic degradation efficiency of TCS (89.9%) compared to bare CoFe2O4 NRs (62.1 %), CuOx(1 wt%)/CoFe2O4 (80.1 %), CuOx(2 wt%)/CoFe2O4 (87.0 %) under visible light (VL) irradiation (λ ≥ 420 nm), respectively. This enhanced performance was attributed to the improved separation effectiveness of photogenerated electron (e-) and hole (h+) in CuOx(3 wt%)/CoFe2O4 NCs. Furthermore, the optimized CuOx(3 wt%)/CoFe2O4 NCs exhibited strong stability and reusability in TCS degradation, as demonstrated by three successive cycles. Genetic screening on Caenorhabditis elegans showed that CuOx(3 wt%)/CoFe2O4 NCs reduced ROS-induced oxidative stress during TCS photocatalytic degradation. ROS levels decreased at 30, 60, and 120-min intervals during TCS degradation, accompanied by improved egg hatching rates. Additionally, expression levels of stress-responsible antioxidant proteins like SOD-3GFP and HSP-16.2GFP were significantly normalized. This study demonstrates the efficiency of CuOx(3 wt%)/CoFe2O4 NCs in degrading TCS pollutants, offers insights into toxicity dynamics, and recommends its use for future environmental remediation.

The effect of using synthetic vs. biological dural substitutes during prenatal and postnatal repair of spina bifida on spinal cord tethering-a review of literature.

Spina bifida is a congenital neural tube closure defect, with myelomeningocele being the most clinically significant open neural tube defect occurring in one in 1000 births worldwide as reported by Phillips LA et al. (Curr Probl Pediatr Adolesc Health Care 47(7):173-177, 2017) and Zerah M and Kulkarni AV (Handb Clin Neurol 112:975-991, 2013). With advances in fetal surgery, this condition can be corrected in utero. Despite such precision surgery, many complications may still arise, with consequent spinal cord tethering being a major one. When the roots of the spinal cord adhere to the spinal canal instead of floating freely within the dural sleeve within the canal, it is termed as "tethering" as discussed by Martínez-Lage JF et al. (Neurocirugia (Astur) 18(4):312-319, 2007). Tethering has a variety of complications, which are best avoided by analyzing the outcomes of the different dural substitutes and improving surgical techniques. This literature review evaluates the use of different dural substitutes in fetal and postnatal surgery, with their effects on spinal cord tethering. Finding a significant difference in spinal cord adherence outcomes between these two groups can help one introspect on the impact of ideal surgical techniques to be implemented, thus reducing subsequent tethering and other future surgical interventions.

Topical Prescription Management.

With recent advances in topical therapies for atopic dermatitis (AD), steroid-sparing options like calcineurin inhibitors, Janus kinase (JAK) inhibitors, and phosphodiesterase-4 (PDE-4) inhibitors are becoming mainstays in therapy, underscoring the importance of careful selection and usage of topical corticosteroids (TCSs) to minimize side effects. Alongside the necessity of emollient use, these steroid-sparing alternatives offer rapid itch relief and efficacy in improving disease severity. While TCSs still hold a prominent role in AD management, promising novel topical treatments like tapinarof and live biotherapeutics to modulate the skin microbiome are also discussed. Overall, the recent addition of novel topical therapies offers diverse options for AD management and underscores the importance of topical treatments in the management of AD.

Left Ventricular Unloading in Extracorporeal Membrane Oxygenation: A Clinical Perspective Derived from Basic Cardiovascular Physiology.

PURPOSE OF REVIEW: To present an abridged overview of the literature and pathophysiological background of adjunct interventional left ventricular unloading strategies during veno-arterial extracorporeal membrane oxygenation (V-A ECMO). From a clinical perspective, the mechanistic complexity of such combined mechanical circulatory support often requires in-depth physiological reasoning at the bedside, which remains a cornerstone of daily practice for optimal patient-specific V-A ECMO care. RECENT FINDINGS: Recent conventional clinical trials have not convincingly shown the superiority of V-A ECMO in acute myocardial infarction complicated by cardiogenic shock as compared with medical therapy alone. Though, it has repeatedly been reported that the addition of interventional left ventricular unloading to V-A ECMO may improve clinical outcome. Novel approaches such as registry-based adaptive platform trials and computational physiological modeling are now introduced to inform clinicians by aiming to better account for patient-specific variation and complexity inherent to V-A ECMO and have raised a widespread interest. To provide modern high-quality V-A ECMO care, it remains essential to understand the patient's pathophysiology and the intricate interaction of an individual patient with extracorporeal circulatory support devices. Innovative clinical trial design and computational modeling approaches carry great potential towards advanced clinical decision support in ECMO and related critical care.

Accelerated aging behavior of degradable and non-degradable microplastics via advanced oxidation and their adsorption characteristics towards tetracycline.

The increasing global utilization of biodegradable plastics due to stringent regulations on traditional plastics has caused a significant rise in microplastic (MPs) pollution in aquatic ecosystems from biodegradable products. However, the environmental behavior of biodegradable MPs remains inadequately elucidated. This study explored the aging processes of polylactic acid (PLA) and polystyrene (PS) under a heat-activated potassium persulfate (K2S2O8) system, as well as their adsorption characteristics towards tetracycline (TCs). In comparison to PS, the surface structure of PLA experienced more pronounced changes over aging, exhibiting evident pits, cracks, and fragmentation. The carbonyl index (CI) and oxygen/carbon ratio (O/C) of PS displayed exponential growth over time, whereas the values for PLA showed linear and exponential increases, respectively. The adsorption capacity of TCs by PS and PLA aged for 6 days increased from 0.312 mg‧g-1 and 0.457 mg‧g-1for original PS and PLA, respectively, to 0.372 mg‧g-1 and 0.649 mg‧g-1. Meanwhile, the adsorption rate (k2 values) for TCs decreased by 42.03 % for PS and 79.64 % for PLA compared to their initial values. The findings indicated that biodegradable PLA-MPs may exhibit higher tetracycline carrying capacities than PS, potentially increasing environmental and organismal risks, particularly in view of aging effects.

Exposure to biocides and its association with atopic dermatitis among children and adolescents: A population-based cross-sectional study in South Korea.

BACKGROUND: Biocides have emerged as a contributor to the rising cases of atopic dermatitis among children and adolescents. Previous animal studies suggested that phenols, parabens, and pyrethroid insecticides present in these products might play a role in atopic dermatitis. However, there's limited epidemiological evidence confirming the individual or combined effects of exposure to these chemicals on atopic dermatitis in young populations. This study aimed to investigate the association between phenol, paraben, and pyrethroid metabolite levels in urine and atopic dermatitis among Korean children and adolescents METHODS: We analyzed 556 preschool children (3-5 years), 701 schoolchildren (6-11 years), and 731 adolescents (12-17 years) enrolled in the 4th Korean National Environmental Health Survey (KoNEHS) (2018-2020). We used logistic regression and Bayesian kernel machine regression to evaluate the association between atopic dermatitis and individual or mixed exposure to urinary triclosan (TCS), parabens (methylparaben, ethylparaben, propylparaben, and butylparaben), and 3-phenoxybenzoic acid (3-PBA) levels. RESULTS: Urinary TCS levels were positively associated with atopic dermatitis in schoolchildren. When stratified by sex, male schoolchildren exhibited an increasing prevalence of atopic dermatitis as their urinary TCS and 3-PBA levels increased. The combined effect of biocide mixtures on atopic dermatitis was also significantly increased in male schoolchildren, with TCS as the main contributor. CONCLUSIONS: These study findings suggest that biocides at levels found in Korean children and adolescents affect atopic dermatitis.

Unsupervised Transfer Learning Method via Cycle-Flow Adversarial Networks for Transient Fault Detection under Various Operation Conditions.

The efficient fault detection (FD) of traction control systems (TCSs) is crucial for ensuring the safe operation of high-speed trains. Transient faults (TFs) can arise due to prolonged operation and harsh environmental conditions, often being masked by background noise, particularly during dynamic operating conditions. Moreover, acquiring a sufficient number of samples across the entire scenario presents a challenging task, resulting in imbalanced data for FD. To address these limitations, an unsupervised transfer learning (TL) method via federated Cycle-Flow adversarial networks (CFANs) is proposed to effectively detect TFs under various operating conditions. Firstly, a CFAN is specifically designed for extracting latent features and reconstructing data in the source domain. Subsequently, a transfer learning framework employing federated CFANs collectively adjusts the modified knowledge resulting from domain alterations. Finally, the designed federated CFANs execute transient FD by constructing residuals in the target domain. The efficacy of the proposed methodology is demonstrated through comparative experiments.

The evolution of cytokinin signaling and its role in development before Angiosperms.

Cytokinin signaling by way of a multistep two-component signaling pathway has been highly examined over the last 20 years with a lot of attention to how its signaling components regulate essential growth and developmental processes from seedlings to senescence. Most studies have focused on Angiosperm plants, particularly Arabidopsis, with very little attention across the rest of the plant kingdom, making it difficult to know if cytokinin-regulated developmental processes are have remained evolutionarily conserved or distinct among different plant groups. Here the prevalence of cytokinin signaling components throughout plants, algae, and other organisms are examined. Particular examination is paid to how minimal sets of these base signaling components are related to development in Bryophytes, a primary group of study outside of Angiosperms. General comparisons of the role of signaling components between these distant groups suggest some evolutionary conservation of function has been maintained across plants as a whole. This review also highlights the need to investigate how cytokinin signaling components, recently identified in every plant group, contribute to development; this will give higher resolution to our understanding of cytokinin roles in development across plant taxa. Also revealed is a strong need to further pursue how cytokinin signaling components recently identified in every plant group contribute to development in order to further dissect these connections.

Prevalence of Endocrine Disrupting Chemicals in the urban wastewater treatment systems of Dehradun, India: Daunting presence of Estrone.

We quantified the occurrences and seasonal variations of the target endocrine disrupting chemicals (EDCs) at four (two major municipals, and two academic institutions) WWTPs in Dehradun city, Uttarakhand, India. The results showed estrone in higher concentrations at µgL-1 levels in influent among the WWTPs, compared to triclosan (TCS) at ngL-1 levels. An astounding concentration of 123.95 µgL-1 was recorded for the estrone in the influent, which is to date the highest ever recorded, globally. Statistical data treatment was performed to test the distribution of the data (Shapiro-Wilk, Anderson-Darling, Lilliefors, and Jarque-Bera tests), and the significant difference between the mean of the wastewater sample population (ANOVA: F statistics, p values, Mann-Whitney test, Tukey's and Dunn's post hoc analysis). Statistical data treatment indicated EDCs concentration with a bi-modal distribution. The Shapiro-Wilk, Anderson-Darling, Lilliefors, and Jarque-Bera tests elucidate a non-normal distribution for the EDCs sample data. A statistically significant difference (F = 8.46; p < 0.0001) in the seasonal data for the abundance of the target EDCs at the WWTPs have been observed. Highest and significantly different mean EDCs concentrations were recorded during the monsoon, compared to the spring (p = 0.025) and summer (p = 0.0004) seasons in the influent waters. The mean influent concentrations of TCS and estrone in monsoon were 66.45 ngL-1 and 78.02 µgL-1, respectively. Maximum removals were recorded for TCS, while maximum negative removal of ∼293% was observed for estrone in the WWTPs. Particularly, the high levels of estrone in the wastewater pose a significant threat as estrone presence could be led to feminization, dysregulation of reproduction in organisms, and carcinogenesis processes in the environment. This study critically highlights the limitation of the WWTPs in the treatment, degradation, and assimilation of EDCs leading to their hyperaccumulation at WWTP effluents, thereby posing a substantial threat to nearby aquatic ecosystems, human health, and the ecological balance of the region.

Transcranial Sonography as a Diagnostic Tool for Depressive Disorders.

BACKGROUND: Transcranial sonography (TCS) is an available and noninvasive neuroimaging method that has been found to reduce the echogenicity of the brainstem raphe (BR) in patients with depression. Applying the criteria of the Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV), we performed a meta-analysis of the diagnostic accuracy of TCS. METHODS: A systematic search was conducted in PubMed, EMBASE, The Cochrane Library, and Web of Science. The databases were searched from inception to December 2021. The quality of the included literature was assessed using the QUADAS-2. Heterogeneity analysis was performed. A summary receiver operating characteristic (SROC) curve was generated to evaluate the diagnostic accuracy of TCS. RESULTS: We included 12 studies with 809 patients. The pooled sensitivity was 0.66 (95% confidence interval [CI]: 0.61-0.71), and the specificity was 0.84 (95% CI: 0.80-0.87). The combined positive likelihood ratio (LR) was 3.84 (95% CI: 2.68-5.51), the negative LR was 0.41 (95% CI: 0.29-0.57), and the diagnostic odds ratio (DOR) was 11.45 (95% CI: 5.57-23.02). The area under the curve (AUC) of the plotted SROC curve was 0.86 (95% CI: 0.83-0.89). The meta-regression and subgroup analyses found no source of heterogeneity. CONCLUSION: TCS has high potential and efficacy in diagnosing depression and may be a reasonable test to perform clinically for the assessment of depression.

Microalgal consortium tolerance to bisphenol A and triclosan in wastewater and their effects on growth, biomolecule content and nutrient removal.

Amongst the many treatments available for the removal of emerging contaminants in wastewater, microalgal cultures have been shown to be effective. However, the effectiveness of exposure of a native microalgal consortium to emerging contaminants such as bisphenol-A (BPA) and triclosan (TCS) to determine the half-maximum effective concentrations (EC50) has not yet been determined. The effect on growth and nutrient removal of such a treatment as well as on the production of biomolecules such as carbohydrates, lipids, and proteins are, at present, unknown. In this study, the EC50 of BPA and TCS (96-hour experiments) was determined using a consortium of native microalgae (Scenedesmus obliquus and Desmodesmus sp.) to define the maximum tolerance to these contaminants. The effect of BPA and TCS in synthetic wastewater (SWW) was investigated in terms of microalgal growth, chlorophyll a (Chl-a), carbohydrate, lipid, and protein content, as well as nutrient removal. Assays were performed in heterotrophic conditions (12/12 light/dark cycles). EC50-96 h values of 17 mg/L and 325 µg/L for BPA and TCS, respectively, were found at 72 h. For an initial microalgal inoculum of ≈ 300 mg TSS/L (total suspended solids per litre), growth increased by 16.1% when exposed to BPA and 17.78% for TCS. At ≈ 500 mg TSS/L, growth increased by 8.25% with BPA and 9.92% with TCS, respectively. At the EC50-96 h concentrations determined in the study, BPA and TCS did not limit the growth of microalgae in wastewater. Moreover, they were found to stimulate the content of Chl-a, carbohydrates, lipids, proteins, and enhance nutrient removal. AVAILABILITY OF DATA AND MATERIAL: Data sharing not applicable to this article as no datasets were generated or analysed during the present study.

Trichosanthin Promotes Anti-Tumor Immunity through Mediating Chemokines and Granzyme B Secretion in Hepatocellular Carcinoma.

Trichosanthin (TCS) is a type I ribosome-inactivating protein extracted from the tuberous root of the plant Trichosanthes. TCS shows promising potential in clinical drug abortion, anti-tumor and immunological regulation. However, the molecular mechanisms of its anti-tumor and immune regulation properties are still not well discovered. In the present study, we investigated the anti-tumor activity of TCS in hepatocellular carcinoma (HCC), both in vitro and in vivo. Both HCC cell lines and xenograft tumor tissues showed considerable growth inhibition after they were treated with TCS. TCS provoked caspase-mediated apoptosis in HCC cells and xenograft tumor tissues. The recruitment of CD8+ T cells to HCC tissues and the expression of chemokines, CCL2 and CCL22, were promoted upon TCS treatment. In addition, TCS induced an upregulation of Granzyme B (GrzB), TNF-α and IFN-γ in HCC tissues, which are the major cytotoxic mediators produced by T cells. Furthermore, TCS also resulted in an increase of mannose-6-phosphate receptor (M6PR), the major receptor of GrzB, in HCC tissues. In summary, these results suggest that TCS perhaps increases T-cell immunity via promoting the secretion of chemokines and accelerating the entry of GrzB to HCC cells, which highlights the potential role of TCS in anti-tumor immunotherapy.

Characterization of Two-Component System gene (TCS) in melatonin-treated common bean under salt and drought stress.

The two-component system (TCS) generally consists of three elements, namely the histidine kinase (HK), response regulator (RR), and histidine phosphotransfer (HP) gene families. This study aimed to assess the expression of TCS genes in P. vulgaris leaf tissue under salt and drought stress and perform a genome-wide analysis of TCS gene family members using bioinformatics methods. This study identified 67 PvTCS genes, including 10 PvHP, 38 PvRR, and 19 PvHK, in the bean genome. PvHK2 had the maximum number of amino acids with 1261, whilst PvHP8 had the lowest number with 87. In addition, their theoretical isoelectric points were between 4.56 (PvHP8) and 9.15 (PvPRR10). The majority of PvTCS genes are unstable. Phylogenetic analysis of TCS genes in A. thaliana, G. max, and bean found that PvTCS genes had close phylogenetic relationships with the genes of other plants. Segmental and tandem duplicate gene pairs were detected among the TCS genes and TCS genes have been subjected to purifying selection pressure in the evolutionary process. Furthermore, the TCS gene family, which has an important role in abiotic stress and hormonal responses in plants, was characterized for the first time in beans, and its expression of TCS genes in bean leaves under salt and drought stress was established using RNAseq and qRT-PCR analyses. The findings of this study will aid future functional and genomic studies by providing essential information about the members of the TCS gene family in beans. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-023-01406-5.

Correlation between Triclosan (TCS) exposure and endometriosis.

Objective: To study the correlation of Triclosan (TCS) exposure with typing and staging of endometriosis, and with other potential influencing factors. Methods: This was a retrospective study. Thirty two patients that were diagnosed with endometriosis by laparoscopy or surgery in Taicang First People's Hospital from May 2020 to December 2021 were enrolled in the endometriosis group, and patients who were confirmed free of endometriosis by surgeries for other purposes during the same period were enrolled as the control group. All blood samples were tested twice in two different vials. The association of TCS exposure level with occurrence, staging, typing of endometriosis, and income of the patients were analyzed. Results: Patients with endometriosis had significantly higher TCS exposure levels than the control group. TCS exposure level in patients with endometriosis was positively correlated with patient income), and was significantly higher in patients with Stage-IV endometriosis than in those with Stage-III and II diseases. TCS exposure levels showed no significant difference among patients with ovarian type, ovarian + peritoneal type, and deep nodular type endometriosis TCS exposure level in patients with endometriosis was positively correlated with the staging of the disease. TCS exposure was highly positively correlated with the staging of the disease in patients with ovarian type endometriosis and in patients with deep nodular endometriosis, but there's no such correlation in patients with ovarian + peritoneal type endometriosis. Conclusion: TCS exposure level in endometriosis patients was higher than that in normal women, and is positively correlated with endometriosis staging and income of the patients.

Therapeutic strategies against potential antibiofilm targets of multidrug-resistant Acinetobacter baumannii.

Acinetobacter baumannii is the causative agent of various hospital-acquired infections. Biofilm formation is one of the various antimicrobial resistance (AMR) strategies and is associated with high mortality and morbidity. Hence, it is essential to review the potential antibiofilm targets in A. baumannii and come up with different strategies to combat these potential targets. This review covers different pathways involved in the regulation of biofilm formation in A. baumannii like quorum sensing (QS), cyclic-di-GMP signaling, two-component system (TCS), outer-membrane protein (ompA), and biofilm-associated protein (BAP). A newly discovered mechanism of electrical signaling-mediated biofilm formation and contact-dependent biofilm modulation has also been discussed. As biofilm formation and its maintenance in A. baumannii is facilitated by these potential targets, the detailed study of these targets and pathways can bring light to different therapeutic strategies such as anti-biofilm peptides, natural and synthetic molecule inhibitors, QS molecule degrading enzymes, and other strategies. These strategies may help in suppressing the lethality of biofilm-mediated infections. Targeting essential proteins/targets which are crucial for biofilm formation and regulation may render new therapeutic strategies that can aid in combating biofilm, thus reducing the recalcitrant infections and morbidity associated with the biofilm of A. baumannii.

Bacterial survival strategies and responses under heavy metal stress: a comprehensive overview.

Heavy metals bring long-term hazardous consequences and pose a serious threat to all life forms. Being non-biodegradable, they can remain in the food webs for a long period of time. Metal ions are essential for life and indispensable for almost all aspects of metabolism but can be toxic beyond threshold level to all living beings including microbes. Heavy metals are generally present in the environment, but many geogenic and anthropogenic activities has led to excess metal ion accumulation in the environment. To survive in harsh metal contaminated environments, bacteria have certain resistance mechanisms to metabolize and transform heavy metals into less hazardous forms. This also gives rise to different species of heavy metal resistant bacteria. Herein, we have tried to incorporate the different aspects of heavy metal toxicity in bacteria and provide an up-to-date and across-the-board review. The various aspects of heavy metal biology of bacteria encompassed in this review includes the biological notion of heavy metals, toxic effect of heavy metals on bacteria, the factors regulating bacterial heavy metal resistance, the diverse mechanisms governing bacterial heavy metal resistance, bacterial responses to heavy metal stress, and a brief overview of gene regulation under heavy metal stress.

Regulation of heterologous subtilin production in Bacillus subtilis W168.

BACKGROUND: Subtilin is a peptide antibiotic (lantibiotic) natively produced by Bacillus subtilis ATCC6633. It is encoded in a gene cluster spaBTCSIFEGRK (spa-locus) consisting of four transcriptional units: spaS (subtilin pre-peptide), spaBTC (modification and export), spaIFEG (immunity) and spaRK (regulation). Despite the pioneer understanding on subtilin biosynthesis, a robust platform to facilitate subtilin research and improve subtilin production is still a poorly explored spot. RESULTS: In this work, the intact spa-locus was successfully integrated into the chromosome of Bacillus subtilis W168, which is the by far best-characterized Gram-positive model organism with powerful genetics and many advantages in industrial use. Through systematic analysis of spa-promoter activities in B. subtilis W168 wild type and mutant strains, our work demonstrates that subtilin is basally expressed in B. subtilis W168, and the transition state regulator AbrB strongly represses subtilin biosynthesis in a growth phase-dependent manner. The deletion of AbrB remarkably enhanced subtilin gene expression, resulting in comparable yield of bioactive subtilin production as for B. subtilis ATCC6633. However, while in B. subtilis ATCC6633 AbrB regulates subtilin gene expression via SigH, which in turn activates spaRK, AbrB of B. subtilis W168 controls subtilin gene expression in SigH-independent manner, except for the regulation of spaBTC. Furthermore, the work shows that subtilin biosynthesis in B. subtilis W168 is regulated by the two-component regulatory system SpaRK and strictly relies on subtilin itself as inducer to fulfill the autoregulatory circuit. In addition, by incorporating the subtilin-producing system (spa-locus) and subtilin-reporting system (PpsdA-lux) together, we developed "online" reporter strains to efficiently monitor the dynamics of subtilin biosynthesis. CONCLUSIONS: Within this study, the model organism B. subtilis W168 was successfully established as a novel platform for subtilin biosynthesis and the underlying regulatory mechanism was comprehensively characterized. This work will not only facilitate genetic (engineering) studies on subtilin, but also pave the way for its industrial production. More broadly, this work will shed new light on the heterologous production of other lantibiotics.

Validation and practical use of Plan2Heat hyperthermia treatment planning for capacitive heating.

BACKGROUND: Capacitive devices are used for hyperthermia delivery, initially mainly in Asia, but nowadays also increasingly in Europe. Treatment planning can be very useful to determine the most effective patient-specific treatment set-up. This paper provides a validation of GPU-based simulations using Plan2Heat for capacitive hyperthermia devices. METHODS: Validation was first performed by comparing simulations with an analytical solution for a spherical object placed inside a uniform electric field. Resolution was 5, 2.5 or 1 mm. Next, simulations for homogeneous and inhomogeneous phantom setups were performed for Thermotron RF8 and Celsius TCS capacitive heating devices at 2.5 mm resolution. Also different combinations of electrode sizes were evaluated. Normalized SAR profiles were compared to phantom measurements from the literature. Possible clinical use of treatment planning was demonstrated for an anal cancer patient, evaluating different treatment set-ups in prone and supine position. RESULTS: Numerical and analytical solutions showed excellent agreement. At the center of the sphere, the error was 5.1%, 2.9% and 0.2% for a resolution of 5, 2.5 and 1 mm, respectively. Comparison of measurements and simulations for both Thermotron RF8 and Celsius TCS showed very good agreement within 5% for all phantom set-ups. Simulations were capable of accurately predicting the penetration depth; a very relevant parameter for clinical application. The patient case illustrated that planning can provide insight by comparing effectiveness of different treatment strategies. CONCLUSION: Plan2Heat can rapidly and accurately predict heating patterns generated by capacitive devices. Thus, Plan2Heat is suitable for patient-specific treatment planning for capacitive hyperthermia.