Comparing outcomes of transcatheter tricuspid valve replacement and medical therapy for symptomatic severe tricuspid regurgitation: a retrospective study.

BACKGROUND: Impaired hospitalizations for heart failure (HHF) and mortality are associated with tricuspid regurgitation (TR). OBJECTIVES: The objective of this study was to investigate the benefit of transcatheter tricuspid valve replacement (TTVR) over guideline-directed medical therapy (GDMT) in patients with symptomatic severe TR. METHODS: Between May 2020 and April 2023, 88 patients with symptomatic severe TR were treated in our center. Of these, 57 patients received GDMT alone, and 31 patients underwent combined TTVR and GDMT. We collected and analyzed baseline data, and follow-up information for both groups. The primary endpoints were all-cause mortality and the combined endpoint (including all-cause mortality and HHF). RESULTS: At a median follow-up of 20 (IQR 10-29) months, significant improvements were shown in TR severity, right ventricular function, and dimensions in TTVR group (all P < 0.001). It also resulted in superior survival rates (75.8% vs. 48.4%, P = 0.019), improved freedom from combined endpoint (61.5% vs. 45.9%, P = 0.007) and fewer major adverse events. After stratification by TRI-SCORE, the subgroup with < 6 points in the TTVR group exhibited a significant difference in the combined endpoint compared to the other subgroups (all P < 0.05), while no significant differences were observed in the GDMT subgroups (P = 0.680). CONCLUSIONS: The utilization of LuX-Valve in TTVR effectively improves TR and is associated with lower rates of major adverse events, HHF and all-cause mortality. The TRI-SCORE may help identify higher-benefit patients with TR from TTVR. Clinical trial registration ClinicalTrials.gov Protocol Registration System (NCT02917980).

The effect of ß-ionone on bacterial cells: the use of specific lux-biosensors.

The diversity of the biological activity of volatile organic compounds (VOCs), including unsaturated ketone ß-ionone, promising pharmacological, biotechnological, and agricultural agent, has aroused considerable interest. However, the functional role and mechanisms of action of VOCs remain insufficiently studied. In this work, the response of bacterial cells to the action of ß-ionone was studied using specific bioluminescent lux-biosensors containing stress-sensitive promoters. We determined that in Escherichia coli cells, ß-ionone induces oxidative stress (PkatG and Pdps promoters) through a specific response mediated by the OxyR/OxyS regulon, but not SoxR/SoxS (PsoxS promoter). It has been shown that ß-ionone at high concentrations (50 µM and above) causes a weak induction of the expression from the PibpA promoter and slightly induces the PcolD promoter in the E. coli biosensors; the observed effect is enhanced in the ΔoxyR mutants. This indicates the presence of some damage to proteins and DNA. ß-Ionone was found to inhibit the bichaperone-dependent DnaKJE-ClpB refolding of heat-inactivated bacterial luciferase in E. coli wild-type and ΔibpB mutant strains. In the cells of the Gram-positive bacterium Bacillus subtilis 168 pNK-MrgA ß-ionone does not cause oxidative stress. Thus, in this work, the specificity of bacterial cell stress responses to the action of ß-ionone was shown.

Transcatheter tricuspid valve replacement with LuX-valve device: Overview of key echocardiographic considerations.

Tricuspid regurgitation is a common valve disease with high incidence and poor prognosis. For elderly patients and those with a history of open heart surgery, second thoracotomy and valve replacement carry a high risk. Transcatheter tricuspid valve replacement (TTVR) has become an alternative treatment for patients with high surgical risk. LuX-Valve is a novel self-expandable valve that does not rely on radial force to anchor the valve annulus. The preliminary results have been satisfactory, and this technology is gradually being adopted in China and around the world. Successful implementation of this technique depends on echocardiographic preoperative screening, intraoperative guidance, and postoperative follow-up. The purpose of this article is to provide a state-of-the-art review of the key points and technical considerations for preoperative screening, intraoperative guidance, and postoperative follow-up for TTVR.

Quorum sensing in bacteria: in silico protein analysis, ecophysiology, and reconstruction of their evolutionary history.

BACKGROUND: Quorum sensing (QS) is a sophisticated cell-to-cell signalling mechanism that allows the coordination of important processes in microbial populations. The AI-1 and AI-2 autoinducer systems are among the best characterized bacterial QS systems at the genetic level. RESULTS: In this study, we present data derived from in silico screening of QS proteins from bacterial genomes available in public databases. Sequence analyses allowed identifying candidate sequences of known QS systems that were used to build phylogenetic trees. Eight categories were established according to the number of genes from the two major QS systems present in each genome, revealing a correlation with specific taxa, lifestyles or metabolic traits. Many species had incomplete QS systems, encoding the receptor protein but not the biosynthesis of the quorum sensing molecule (QSMs). Reconstruction of the evolutionary history of the LuxR family and prediction of the 3D structure of the ancestral protein suggested their monomeric configuration in the absence of the signal molecule and the presence of a cavity for its binding. CONCLUSIONS: Here we correlate the taxonomic affiliation and lifestyle of bacteria from different genera with the QS systems encoded in their genomes. Moreover, we present the first ancestral reconstruction of the LuxR QS receptors, providing further insight in their evolutionary history.

In Vitro Determination of Temperature-Dependent DNA Binding of the Evening Complex Using Electrophoretic Mobility Shift Assays.

Electrophoretic mobility shift assays (EMSAs) of DNA-binding proteins and labeled DNA allow the qualitative and quantitative characterization of protein-DNA complex formation using native (nondenaturing) polyacrylamide or agarose gel electrophoresis. By varying the incubation temperature of the protein-DNA binding reaction and maintaining this temperature during electrophoresis, temperature-dependent protein-DNA interactions can be investigated. Here, we provide examples of the binding of a transcriptional repressor complex called the Evening Complex, comprising the DNA-binding protein LUX ARRYTHMO (LUX), the scaffold protein EARLY FLOWERING 3 (ELF3), and the adapter protein ELF4, to its cognate DNA and demonstrate direct detection and visualization of thermoresponsive binding in vitro. As negative controls we use the LUX DNA-binding domain and LUX full length protein, which do not exhibit temperature-dependent DNA binding.

Transcatheter tricuspid valve replacement for functional tricuspid regurgitation after left-sided valve surgery: A single-center experience.

BACKGROUND: Functional tricuspid regurgitation (FTR) following left-sided valve surgery (LSVS) is of clinical significance due to its high recurrence and mortality rates. Transcatheter therapy presents a potential solution to address this issue. AIMS: The study aimed to assess the safety and efficacy of transcatheter tricuspid valve replacement using the Lux-Valve system in a single center for patients with FTR after LSVS. METHODS: From June 2020 to April 2023, 20 patients with symptomatic severe FTR after LSVS were referred to our center. A multidisciplinary cardiac team evaluated these patients for suitability for transcatheter tricuspid valve replacement with Lux-Valve systems. Primary efficacy and safety endpoints were immediate postoperative tricuspid regurgitation severity ≤ moderate and major adverse events during follow-up. RESULTS: Twenty patients (average age 65.7 ± 7.4 years; 65.0% women) successfully underwent Lux-Valve system implantation after LSVS. All patients achieved ≤ moderate tricuspid regurgitation immediately after the procedure. Only one patient (5.0%) experienced a procedure-related major adverse event, leading to in-hospital mortality due to pulmonary infection. At the 6-month follow-up, 17 patients (89.5%) improved to New York Heart Association functional class I to II (p < 0.001). The overall Kansas City Cardiomyopathy Questionnaire score significantly improved (35.9 ± 6.7 points to 58.9 ± 5.8 points, p < 0.001). CONCLUSION: The Lux-Valve system was found to be safe and effective for treating FTR after LSVS. It resulted in positive early outcomes, including a significant reduction in FTR, improved functional status, and enhanced quality of life, especially in high-risk patients.

Transjugular tricuspid valve-in-ring replacement using the novel system under three-dimensional printing guidance.

Recurrent tricuspid regurgitation after failed ring annuloplasty is associated with high mortality rates and unfavourable clinical outcomes. Transcatheter tricuspid valve-in-ring (TVIR) replacement offers an alternative to high-risk surgical reoperation, but challenges remain. We present a case of a 67-year-old male who underwent tricuspid annuloplasty 3 years ago and developed severe recurrent tricuspid regurgitation (regurgitation volume = 36 mL) 6 months ago. To avoid a high-risk thoracotomy, we finally performed TVIR replacement using the novel device, LuX-Valve Plus system, via the transjugular approach. Cardiovascular three-dimensional printing technology was utilized to investigate the distinct advantages offered by the new device in this specific intervention, as well as to simulate the procedure. Successful TVIR replacement resulted in significant symptomatic improvement. TVIR replacement with the LuX-Valve Plus system is feasible for failed annuloplasty ring cases. Patient-specific three-dimensional printed models enable personalized procedural planning, enhancing safety and precision.

Head-to-Head Comparison of 2 Paclitaxel-Coated Balloons for Femoropopliteal Lesions.

BACKGROUND: There is a scarcity of published head-to-head comparisons between different paclitaxel-coated angioplasty balloons. More prospective safety data to support the health care economic reimbursement processes are needed. OBJECTIVES: The aim of this study was to report the safety and efficacy of the Passeo-18 Lux drug-coated balloon (DCB) (Biotronik AG) for the treatment of symptomatic peripheral artery disease caused by stenosis, restenosis, or occlusion of the femoral and/or popliteal arteries. METHODS: A total of 302 patients were randomized 1:1 and assigned to the Passeo-18 Lux DCB (study device) group or the IN.PACT Admiral DCB (control device, Medtronic Vascular) group for testing of noninferiority. The primary efficacy endpoint was freedom from clinically driven target lesion revascularization at 12 months. The primary safety endpoint was a composite of freedom from device-/procedure-related death through 30 days postindex procedure, major target limb amputation, and clinically driven target vessel revascularization at 12 months. RESULTS: At 12 months, 130 of 134 patients in the IN.PACT Admiral group had freedom from clinically driven target lesion revascularization (97.0%) compared with 137 of 141 patients in the Passeo-18 Lux group (97.2%). The primary safety endpoint showed 96.3% in the control group vs 95.7% in the study device group. The null hypothesis of inferiority on both efficacy and safety was rejected. The Kaplan-Meier estimate of primary patency at 1 year was 88.7% in the control arm vs 91.5% in the study device arm. CONCLUSIONS: The Passeo-18 Lux and the IN.PACT Admiral DCBs demonstrate comparable results with excellent effectiveness and safety through 12 months for femoropopliteal interventions.

USE of IMplanting the Biotronik PassEo-18 Lux drug coated balloon to treat failing haemodialysis arteRiovenous FIstulas and grafts (SEMPER FI Study).

BACKGROUND: Plain old balloon angioplasty has been the mainstay of treatment for arteriovenous fistula (AVF) stenoses. Recent studies suggest that drug coated balloons (DCB) may significantly reduce re-intervention rates on native and recurrent lesions. The Passeo-18 Lux DCB (Biotronik AG, Buelach, Switzerland) is packaged with a 3.0 µg/mm2 dose of paclitaxel. The hypothesis is that its use provides better target lesion primary patency (TLPP), primary assisted patency (PP), secondary patency (SP) rates and reduces the number of visits for re-intervention in a cohort of patients with stenotic AVF and arteriovenous grafts (AVGs). METHODS: The USE of IMplanting the Biotronik PassEo-18 Lux DCB to treat failing haemodialysis arteRiovenous FIstulas and grafts trial (SEMPER FI) was a prospective double-centre, multi-investigator, non-consecutive, non-blinded single-arm study investigating the efficacy and safety of the Passeo-18 Lux DCB in patients with stenotic AVF/AVG lesions between January 2021 and January 2022. Patient demographics, clinical characteristics, vascular access history, operative indications, details and outcomes were collected prospectively. TLPP, circuit access primary patency (CAP), PP, SP and deaths 6- and 12-months post-intervention were studied. RESULTS: Ninety-one patients with 110 lesions were recruited across the two centres. 62.6% (n = 57) were male with a median age of 63.5 years (SD = 10.5). 62.6% (n = 57) were taking anti-platelets. Eighty-five AVFs and six AVGs were treated. 60% (n = 54) of AVFs intervened were radiocephalic. 52.7% (n = 58) of targeted lesions were juxta-anastomotic stenosis (JAS) and one-third (n = 33) at the AVF/AVG outflow. 70.9% (n = 78) of lesions were recurrent. Median time from last intervention was 219 days. 78% of target lesions (n = 85) and circuits (n = 70) were patent at 6-months, of which 96.7% (n = 87) of those requiring assisted intervention were patent. CONCLUSION: This study shows that the Passeo-18 Lux DCB can be an effective and safe tool in the treatment of failing haemodialysis AVFs/AVGs.

Using Light Meters to Investigate the Light-Myopia Association - A Literature Review of Devices and Research Methods.

With the increasing prevalence of myopia, evaluating its relationship with objective light exposure as a potential adjustable environmental factor in myopia development has been an emerging research field in recent years. From a thorough literature search, we identify ten wearable light meters from human studies on light exposure and myopia and present an overview of their parameters, thereby demonstrating the wide between-device variability and discussing its implications. We further identify 20 publications, including two reanalyses, reporting investigations of light-myopia associations with data from human subjects wearing light meters. We thoroughly review the publications with respect to general characteristics, aspects of data collection, participant population, as well as data analysis and interpretation, and also assess potential patterns regarding the absence or presence of light-myopia associations in their results. In doing so, we highlight areas in which more research is needed as well as several aspects that warrant consideration in the study of light exposure and myopia.

Resolving phenylephrine HCl and guaifenesin enantiomers on cellulose-based chiral stationary phases: Separation of four enantiomers on 50-mm column.

Chiral high performance liquid chromatographic technique usually employs polysaccharide-based stationary phases in a normal phase mode. This frequently generates large waste of organic solvents. Using shorter columns of 50 mm length as well as a mobile phase with a high water percentage are common approaches for greening this analytical technique. In this context, a new chiral chromatographic technique was developed for simultaneous enantio-separation of phenylephrine HCl and guaifenesin racemates. Four 50 mm cellulose-based columns were experimented to separate the four enantiomers in a reversed phase mode. A face centered design was then employed to optimize the mobile phase acetonitrile% and flow rate on Lux Cellulose-1 (50 × 4.6 mm, 5 µm). The simultaneous resolution of the cited drugs enantiomers was achieved using acetonitrile-water (30:70, by volume), with a flow rate of 0.5 ml min-1 . These optimized chromatographic conditions separate the enantiomers in 7 min running time, generating about 1.0 ml acetonitrile per run. The proposed method was favorably compared with other reported chiral ones in terms of waste volume generated and analysis time required.

Arterial stiffness and the reallocation of time between device-measured 24-hour movement behaviours: A compositional data analysis.

BACKGROUND AND AIMS: Arterial stiffness predicts cardiovascular morbidity and mortality. We aimed to quantify the differences in arterial stiffness associated with reallocating time between 24-h movement behaviours. METHODS: This observational cross-sectional study included Luxembourg residents aged 25-79y who each provided ≥4 valid days of triaxial accelerometry (n = 1001). Covariable adjusted compositional isotemporal substitution models were used to examine if theoretical reallocations of time between device-measured sedentariness, the sleep period, light physical activity (PA), and moderate-to-vigorous PA (MVPA) were associated with the percentage difference in carotid-femoral pulse wave velocity (cfPWV). We further investigated if replacing sedentary time accumulated in prolonged (≥30 min) with non-prolonged (<30 min) bouts was associated with arterial stiffness. The results are presented as 30 min time exchanges (ß (95% confidence interval)). RESULTS: Beneficial associations with lower cfPWV were observed when reallocating time to MVPA from the sleep period (-1.38 (-2.63 to -0.12) %), sedentary time (-1.70 (-2.76 to -0.62) %), and light PA (-2.51 (-4.55 to -0.43) %), respectively. Larger associations in the opposite direction were observed when reallocating MVPA to the same behaviours (for example, replacing MVPA with sedentary time: 2.50 (0.85-4.18) %). Replacing prolonged with non-prolonged sedentary time was not associated with cfPWV (-0.27 (-0.86 to 0.32) %). In short sleepers, reallocating sedentary time to the sleep period was favourable (-1.96 (-3.74 to -0.15) %). CONCLUSIONS: Increasing or at least maintaining MVPA appears to be important for arterial health in adults. Extending sleep in habitually short sleepers, specifically by redistributing sedentary time, may also be important.

Bacterial Lux Biosensors in Genotoxicological Studies.

The aim of this study was to assess the applicability of the bacterial lux biosensors for genotoxicological studies. Biosensors are the strains of E. coli MG1655 carrying a recombinant plasmid with the lux operon of the luminescent bacterium P. luminescens fused with the promoters of inducible genes: recA, colD, alkA, soxS, and katG. The genotoxicity of forty-seven chemical compounds was tested on a set of three biosensors pSoxS-lux, pKatG-lux and pColD-lux, which allowed us to estimate the oxidative and DNA-damaging activity of the analyzed drugs. The comparison of the results with the data on the mutagenic activity of these drugs from the Ames test showed a complete coincidence of the results for the 42 substances. First, using lux biosensors, we have described the enhancing effect of the heavy non-radioactive isotope of hydrogen deuterium (D2O) on the genotoxicity of chemical compounds as possible mechanisms of this effect. The study of the modifying effect of 29 antioxidants and radioprotectors on the genotoxic effects of chemical agents showed the applicability of a pair of biosensors pSoxS-lux and pKatG-lux for the primary assessment of the potential antioxidant and radioprotective activity of chemical compounds. Thus, the results obtained showed that lux biosensors can be successfully used to identify potential genotoxicants, radioprotectors, antioxidants, and comutagens among chemical compounds, as well as to study the probable mechanism of genotoxic action of test substance.

Treatment of severe tricuspid regurgitation induced by permanent pacemaker lead: Transcatheter tricuspid valve replacement with the guidance of 3-dimensional printing.

Background: Lead-induced tricuspid regurgitation is one of the complications after permanent pacemaker implantation (PPI) and refers to tricuspid regurgitation (TR) caused by the lead in the right ventricle (RV). Objectives: To study the clinical characteristics of severe TR after PPI and the effect of transcatheter tricuspid valve replacement (TTVR) with the guidance of 3-dimensional (3D) printing. Methods: This study was a single-center, descriptive study. Six patients with severe TR after PPI were enrolled in Xijing Hospital from January 2020 to May 2020. Before TTVR, the 3D printed tricuspid valve (TV) model was used for evaluation in the bench test. LuX-Valve was implanted under the guidance of TEE and x-ray fluoroscopy, and all patients underwent transatrial access. Six patients' data were collected at baseline, before discharge, and 6 months, 1 year and 2 years after TTVR. Results: The LuX-Valve was successfully implanted in 6 patients, TR was significantly reduced to ≤2+, and no deaths or cardiopulmonary bypass occurred during procedures. Three cases were caused by TV expansion: Patient #4 had TR caused by lead adhesion to TV, Patient #2 had TR caused by lead winding, and Patient #6 had TR caused by lead impingement on TV. During the 2-year follow-up, TTE revealed that 5 patients had no/trace regurgitation, and one patient (Patient #5) had mild regurgitation. All 6 patients (100.0%) reached primary endpoints. Conclusion: TTVR guided by 3D printing is safe and effective in the treatment of severe TR associated with permanent pacemaker lead, providing prospects and possibilities for the precise treatment of TV-related diseases.Clinical Trial Registration: ClinicalTrials.gov Protocol Registration System (NCT02917980).

OsLUX Confers Rice Cold Tolerance as a Positive Regulatory Factor.

During the early seedling stage, rice (Oryza sativa L.) must overcome low-temperature stress. While a few cold-tolerance genes have been characterized, further excavation of cold-resistance genes is still needed. In this study, we identified a cold-induced transcription factor-LUX ARRHYTHMO (LUX)-in rice. OsLUX was found to be specifically expressed in leaf blades and upregulated by both cold stress and circadian rhythm. The full-length OsLUX showed autoactivation activity, and the OsLUX protein localized throughout the entire onion cell. Overexpressing OsLUX resulted in increased cold tolerance and reduced ion leakage under cold-stress conditions during the seedling stage. In contrast, the knockout of OsLUX decreased seedling cold tolerance and showed higher ion leakage compared to the wild type. Furthermore, overexpressing OsLUX upregulated the expression levels of oxidative stress-responsive genes, which improved reactive oxygen species (ROS) scavenging ability and enhanced tolerance to chilling stress. Promoter analysis showed that the OsLUX promoter contains two dehydration-responsive element binding (DREB) motifs at positions -510/-505 (GTCGGa) and -162/-170 (cCACCGccc), which indicated that OsDREB1s and OsDREB2s probably regulate OsLUX expression by binding to the motif to respond to cold stress. Thus, OsLUX may act as a downstream gene of the DREB pathway. These results demonstrate that OsLUX serves as a positive regulatory factor of cold stress and that overexpressing OsLUX could be used in rice breeding programs to enhance abiotic stress tolerance.

Enantioseparation, quantification, molecular docking and molecular dynamics study of five ß-adrenergic blockers on Lux-Cellulose-2 column.

Enantioseparation of five ß-adrenergic blockers was studied using two mobile phases on a cellulose tris(3-chloro-4-methylphenylcarbamate) (Lux-Cellulose-2) chiral column in normal phase mode. The first mobile phase composed of n-hexane: ethanol: diethylamine 60: 40: 0.1 by volume has successfully resolved the chromatographic peaks of three pairs of ß-adrenergic blockers namely, bisoprolol, carvedilol and atenolol. A mixture of n-hexane: ethanol: diethyl amine 75: 25: 0.1 by volume was used as the second mobile phase to separate the four pairs of enantiomers, metoprolol, carvedilol, nebivolol and atenolol with high resolution values. The mobile phases were pumped at a flow rate 1 mL/min with column temperature 25 °C using a UV detector at 230 nm. Molecular docking simulations of the five pairs of enantiomers was carried out in the cavities of the chiral stationary phase to gain a better understanding of the interaction between analyte enantiomers and chiral stationary phase and to better understand the mechanism of chiral recognition. According to the results, hydrogen bond interactions and π-π- interactions were the main types of interaction involved in the chiral recognition. Molecular dynamics simulation was performed to investigate the solvent effect on the interaction of the five pair of enantiomers in the chiral stationary phase cavity under dynamic conditions.

Photorhabdus lux-operon heat shock-like regulation.

For decades, transcription of Photorhabdus luminescens lux-operon was considered being constitutive. Therefore, this lux-operon has been used for measurements in non-specific bacterial luminescent biosensors. Here, the expression of Photorhabdus lux-operon under high temperature was studied. The expression was researched in the natural strain Photorhabdus temperata and in the heterologous system of Escherichia coli. P. temperata FV2201 bacterium was isolated from soil in the Moscow region (growth optimum 28 °C). We showed that its luminescence significantly increases when the temperature rises to 34 °C. The increase in luminescence is associated with an increase in the transcription of luxCDABE genes, which was confirmed by RT-PCR. The promoter of the lux-operon of the related bacterium P. luminescens ZM1 from the forests of Moldova, being cloned in the heterologous system of E. coli, is activated when the temperature rises from room temperature to 42 °C. When heat shock is caused by ethanol addition, transcription of lux-operon increases only in the natural strain of P. temperata, but not in the heterologous system of E. coli cells. In addition, the activation of the lux-operon of P. luminescens persists in E. coli strains deficient in both the rpoH and rpoE genes. These results indicate the presence of sigma 32 and sigma 24 independent heat-shock-like mechanism of regulation of the lux-operon of P. luminescens in the heterologous E. coli system.

Development of Fluorescent Bacteria with Lux and Riboflavin Genes.

Lumazine protein from marine luminescent bacteria of Photobacterium species bind with very high affinity to the fluorescent chromophore 6,7-dimethyl-8-ribitylumazine. The light emission of bacterial luminescent systems is used as a sensitive, rapid, and safe assay for an ever-increasing number of biological systems. Plasmid pRFN4, containing the genes encoding riboflavin from the rib operon of Bacillus subtilis, was designed for the overproduction of lumazine. To construct fluorescent bacteria for use as microbial sensors, novel recombinant plasmids (pRFN4-Pp N-lumP and pRFN4-Pp luxLP N-lumP) were constructed by amplifying the DNA encoding the N-lumP gene (luxL) from P. phosphoreum and the promoter region (luxLP) present upstream of the lux operon of the gene by PCR and ligating into the pRFN4-Pp N-lumP plasmid. A new recombinant plasmid, pRFN4-Pp luxLP-N-lumP, was constructed with the expectation that the fluorescence intensity would be further increased when transformed into Escherichia coli. When this plasmid was transformed into E. coli 43R, the fluorescence intensity of transformants was 500 times greater than that of E. coli alone. As a result, the recombinant plasmid in which the gene encoding N-LumP and DNA containing the lux promoter exhibited expression that was so high as to show fluorescence in single E. coli cells. The fluorescent bacterial systems developed in the present study using lux and riboflavin genes can be utilized in the future as biosensors with high sensitivity and rapid analysis times.

Biological activity of volatiles produced by the strains of two Pseudomonas and two Serratia species.

Volatile compounds emitted by bacteria can play a significant role in interacting with microorganisms, plants, and other organisms. In this work, we studied the effect of total gaseous mixtures of organic as well as inorganic volatile compounds (VCs) and individual pure volatile organic compounds (VOCs: ketones 2-nonanone, 2-heptanone, 2-undecanone, a sulfur-containing compound dimethyl disulfide) synthesized by the rhizosphere Pseudomonas chlororaphis 449 and Serratia plymuthica IC1270 strains, the soil-borne strain P. fluorescens B-4117, and the spoiled meat isolate S. proteamaculans 94 strain on Arabidopsis thaliana plants (on growth and germination of seeds). We demonstrated that total mixtures of volatile compounds emitted by these strains grown on Luria-Bertani agar, Tryptone Soya Agar, and Potato Dextrose Agar media inhibited the A. thaliana growth. When studied bacteria grew on Murashige and Skoog (MS) agar medium, volatile mixtures produced by bacteria could stimulate the growth of plants. Volatile compounds of bacteria slowed down the germination of plant seeds; in the presence of volatile mixtures of P. fluorescens B-4117, the seeds did not germinate. Of the individual VOCs, 2-heptanone had the most potent inhibitory effect on seed germination. We also showed that the tested VOCs did not cause oxidative stress in Escherichia coli cells using specific lux-biosensors. VOCs reduced the expression of the lux operon from the promoters of the katG, oxyS, and soxS genes (whose products involved in the protection of cells from oxidative stress) caused by the action of hydrogen peroxide and paraquat, respectively.

Phytochromes and flowering: legumes do it another way.

Phytochromes have a crucial role in the regulation of flowering in many plants, but the underlying molecular mechanisms vary among species. Recently, Lin et al. described a unique phytochrome A (phyA)-controlled photoperiodic flowering pathway in soybean (Glycine max), revealing a novel mechanism for photoperiodic regulation of flowering.