An overview of plasmid transfer in the plant microbiome.

Plant microbiomes are pivotal for healthy plant physiological development. Microbes live in complex co-association with plant hosts, and interactions within these microbial communities vary with plant genotype, plant compartment, phenological stage, and soil properties, among others. Plant microbiomes also harbor a substantial and diverse pool of mobile genes encoded on plasmids. Several plasmid functions attributed to plant-associated bacteria are relatively poorly understood. Additionally, the role of plasmids in disseminating genetic traits within plant compartments is not well known. Here, we present the current knowledge on the occurrence, diversity, function, and transfer of plasmids in plant microbiomes, emphasizing the factors that could modulate gene transfer in-planta. We also describe the role of the plant microbiome as a plasmid reservoir and the dissemination of its genetic material. We include a brief discussion on the current methodological limitations in studying plasmid transfer within plant microbiomes. This information could be useful to elucidate the dynamics of the bacterial gene pools, the adaptations different organisms have made, and variations in bacterial populations that might have never been described before, particularly in complex microbial communities associated with plants in natural and anthropogenic impacted environments.

Horizontal Gene Transfer of an IncP1 Plasmid to Soil Bacterial Community Introduced by Escherichia coli through Manure Amendment in Soil Microcosms.

The quantification and identification of new plasmid-acquiring bacteria in representative mating conditions is critical to characterize the risk of horizontal gene transfer in the environment. This study aimed to quantify conjugation events resulting from manure application to soils and identify the transconjugants resulting from these events. Conjugation was quantified at multiple time points by plating and flow cytometry, and the transconjugants were recovered by fluorescence-activated cell sorting and identified by 16S rRNA sequencing. Overall, transconjugants were only observed within the first 4 days after manure application and at values close to the detection limits of this experimental system (1.00-2.49 log CFU/g of manured soil, ranging between 10-5 and 10-4 transconjugants-to-donor ratios). In the pool of recovered transconjugants, we found amplicon sequence variants (ASVs) of genera whose origin was traced to soils (Bacillus and Nocardioides) and manure (Comamonas and Rahnella). This work showed that gene transfer from fecal to soil bacteria occurred despite the less-than-optimal conditions faced by manure bacteria when transferred to soils, but these events were rare, mainly happened shortly after manure application, and the plasmid did not colonize the soil community. This study provides important information to determine the risks of AMR spread via manure application.

IncHI1A plasmids potentially facilitate horizontal flow of antibiotic resistance genes to pathogens in microbial communities of urban residential sewage.

Horizontal gene transfer via plasmids is important for the dissemination of antibiotic resistance genes among medically relevant pathogens. Specifically, the transfer of IncHI1A plasmids is believed to facilitate the spread of antibiotic resistance genes, such as carbapenemases, within the clinically important family Enterobacteriaceae. The microbial community of urban wastewater treatment plants has been shown to be highly permissive towards conjugal transfer of IncP1 plasmids. Here, we tracked the transfer of the P1 plasmid pB10 and the clinically relevant HI1A plasmid R27 in the microbial communities present in urban residential sewage entering full-scale wastewater treatment plants. We found that both plasmids readily transferred to these communities and that strains in the sewage were able to further disseminate them. Furthermore, R27 has a broad potential host range, but a low host divergence. Interestingly, although the majority of R27 transfer events were to members of Enterobacteriaceae, we found a subset of transfer events to other families, even other phyla. This indicates that HI1A plasmids facilitate horizontal gene transfer both within Enterobacteriaceae, but also across families of, in particular, Gammaproteobacteria, such as Moraxellaceae, Pseudomonadaceae and Shewanellaceae. pB10 displayed a similar potential host range to R27. In contrast to R27, pB10 had a high host divergence. By culture enrichment of the transconjugant communities, we show that sewage strains of Enterobacteriaceae and Aeromonadaceae can stably maintain R27 and pB10, respectively. Our results suggest that dissemination in the urban residual water system of HI1A plasmids may result in an accelerated acquisition of antibiotic resistance genes among pathogens.

Renal replacement therapy-requiring acute kidney injury due to tubulointerstitial nephritis and uveitis syndrome: case report.

BACKGROUND: Acute kidney injury is a major challenge for today's healthcare systems around the globe. Renal replacement therapy has been shown to be beneficial in acute kidney injury, but treatment highly depends on the cause of the acute kidney injury. One less common cause is tubulointerstitial nephritis, which comes in different entities. A very rare type of tubulointerstitial nephritis is tubulointerstitial nephritis and uveitis syndrome, in which the patient presents with additional uveitis. CASE PRESENTATION: A 19-year-old caucasian male presented with mild dyspnea, lack of appetite, weight loss, and moderate itchiness. Lab results showed an acute kidney injury with marked increase of serum creatinine. The patient was started on prednisolone immediately after admission. As the patient in this case showed symptoms of uremia on admission, we decided to establish renal replacement therapy, which is unusual in tubulointerstitial nephritis and uveitis syndrome. During his course of dialysis, the patient developed symptoms of sepsis probably due to a catheter-related infection requiring intensive care and antibiotic treatment, which had to be terminated early as the patient developed a rash. Intensified immunosuppression, combined with antibiotics, significantly resolved excretory kidney dysfunction. CONCLUSIONS: Since both the primary inflammatory process and the secondary infectious complication significantly impaired excretory kidney function, kidney function of younger individuals with new-onset anterior uveitis should be monitored over time and during follow-up.

AKI Epidemiology and Outcomes: A Retrospective Cohort Study from the Prenephrology Era.

BACKGROUND: Acute kidney injury substantially worsens the prognosis of hospitalized patients. The Brandenburg Medical School was founded in 2014, and a nephrology section was opened in summer 2017. The aim of the study was to analyze AKI epidemiology and outcomes in one of two university hospitals belonging to the medical school. The period of interest dated from January to December 2015. METHODS: The investigation was designed as a single-center, retrospective cohort study at the Brandenburg Hospital of the Brandenburg Medical School. All in-hospital patients treated between January and the end of December 2015 were included. AKI was defined as specified in the 2012 published KDIGO criteria (criteria 1 and 2). Four parameters were evaluated in particular: AKI incidence, in-hospital mortality, frequency of renal replacement therapy, and renal recovery during the stay at the hospital. RESULTS: A total number of 5,300 patients were included in the analysis. AKI was diagnosed in 490 subjects (10.1%). The in-hospital mortality was 26%. The following conditions/parameters significantly differed between survivors (s) and nonsurviving (ns) subjects: duration of in-hospital treatment (s > ns), AKI onset (outpatient vs. in-hospital) (outpatient in s > ns), dialysis due to AKI (s < ns), vasopressor administration (s < ns), and invasive ventilation (s < ns). 5.6% received dialysis therapy, and renal recovery occurred in 31% of all surviving AKI subjects. CONCLUSION: Both, the AKI incidence and the frequency of dialysis were lower than reported in the literature. However, fewer subjects recovered from AKI. These discrepant findings possibly result from the lack of prehospitalization creatinine values, the lack of follow-up data, and a generally lower awareness for the need to perform renal replacement therapy in AKI.

A surprisingly complex aqueous chemistry of the simplest amino acid. A pulse radiolysis and theoretical study on H/D kinetic isotope effects in the reaction of glycine anions with hydroxyl radicals.

A pulse radiolysis study was carried out of the reaction rate constants and kinetic isotope effects of hydroxyl-radical-induced H/D abstraction from the most-simple alpha-amino acid glycine in its anionic form in water. The rate constants and yields of three predominantly formed radical products, glycyl (NH2-*CH-CO2-), aminomethyl (NH2-*CH2), and aminyl (*NH-CH2-CO2-) radicals, as well as of their partially or fully deuterated analogs, were found to be of comparable magnitude. The primary, secondary, and primary/secondary H/D kinetic isotope effects on the rate constants were determined with respect to each of the three radicals. The unusual variety of products for such an elementary reaction between two small and simple species indicates a complex mechanism with several reactions taking place simultaneously. Thus, a theoretical modeling of the reaction mechanism and kinetics in the gas- and aqueous phase was performed by using the unrestricted density functional theory with the BB1K functional (employing the polarizable continuum model for the aqueous phase), unrestricted coupled cluster UCCSD(T) method, and improved canonical variational theory. Several hydrogen-bonded prereaction complexes and transition states were detected. In particular, the calculations pointed to a significant mechanistic role of the three-electron two-orbital (sigma/sigma* N therefore O) hemibonded prereaction complexes in the aqueous phase. A good agreement with the experimental rate constants and kinetic isotope effects was achieved by downshifting the calculated reaction barriers by 3 kcal mol(-1) and damping the NH(D) stretching frequency by a factor of 0.86.

Students admitted to university who fail: hidden disabilities affecting students performance / Estudiantes que ingresan a la universidad y fracasan en sus estudios: discapacidades ocultas que afectan el rrendimiento de los estudiantes

OBJECTIVE: To compare grade point averages and social adjustment and academic difficulties of students with or without a hidden disability at The University of the West Indies, Mona, Jamaica. METHODS: Comparison groups were identified through the University of the West Indies (UWI) Health Centre, peer-counselling training programme and an undergraduate class. The 165 participants completed a checklist on health, social and academic concerns and provided a copy of their transcripts. students were screened for hidden disabilities including Attention Deficit Hyperactivity Disorder (ADHD) and psychiatric morbidity. RESULTS: Students with hidden disabilities consistently performed poorer academically than their non-disabled peers, and students with ADHD performed the worst. The high levels of distress common to students with a hidden disability may explain the difference in performance between them and non-disabled students. Students' ability to manage their time, irrespective of having a disability, was singled out as important for obtaining good grades. CONCLUSIONS: Potentially brilliant students are at risk of failing out of university because of hidden disabilities and the associated emotional and social challenges.

OBJETIVO: Comparar los promedios generales de calificaciones (PGC) y el ajuste social y las dificultades académicas de los estudiantes con o sin discapacidades ocultas, en la Universidad de West Indies, Mona, Jamaica. MÉTODOS: Se identificaron grupos de comparación en el Centro de Salud de la Universidad de West Indies (UWI), el programa de adiestramiento para el asesoramiento entre iguales, y una clase de pregrado. Los 165 participantes completaron una lista de control (checklist) de asuntos de salud, sociales y académicos, y entregaron una copia de su expediente académico. Los estudiantes fueron sometidos a un pesquisaje a fin de detectar sus discapacidades ocultas, incluyendo el trastorno de hiperactividad con déficit de atención (THDA) y la morbilidad psiquiátrica. RESULTADOS: Los estudiantes con discapacidades ocultadas tuvieron un rendimiento académico sistemáticamente más pobre que sus iguales no discapacitados, y los estudiantes con THDA fueron los de peor rendimiento. Los altos niveles de distrés común a los estudiantes con alguna discapacidad oculta, pueden explicar la diferencia en rendimiento entre ellos y los estudiantes sin discapacidades: La capacidad de los estudiantes para administrar su tiempo, independientemente de estar afectados o no por alguna discapacidad - fue señalada como un elemento importante para la obtención de buenas calificaciones. CONCLUSIONES: Estudiantes potencialmente brillantes, se hallan en riesgo de fracasar académicamente en la Universidad, debido a discapacidades ocultas y retos emocionales y sociales asociados con ellas.

Students admitted to university who fail: hidden disabilities affecting students' performance.

OBJECTIVE: To compare grade point averages and social adjustment and academic difficulties of students with or without a hidden disability at The University of the West Indies, Mona, Jamaica. METHODS: Comparison groups were identified through The University of the West Indies (UWI) Health Centre, peer-counselling training programme and an undergraduate class. The 165 participants completed a checklist on health, social and academic concerns and provided a copy of their transcripts. Students were screened for hidden disabilities including attention deficit hyperactivity disorder (ADHD) and psychiatric morbidity. RESULTS: Students with hidden disabilities consistently performed poorer academically than their non-disabled peers, and students with ADHD performed the worst. The high levels of distress common to students with a hidden disability may explain the difference in performance between them and non-disabled students. Students'ability to manage their time, irrespective of having a disability, was singled out as important for obtaining good grades. CONCLUSIONS: Potentially brilliant students are at risk of failing out of university because of hidden disabilities and the associated emotional and social challenges.

One-electron reduction of selenomethionine oxide.

Experimental evidence is provided that selenomethionine oxide (MetSeO) is more readily reducible than its sulfur analogue, methionine sulfoxide (MetSO). Pulse radiolysis experiments reveal an efficient reaction of MetSeO with one-electron reductants, such as e(aq)-, (k = 1.2x10(10) M(-1) s(-1)), CO2*- (k = 5.9x10(8) M(-1) s(-1)) and (CH3)2 C*OH (k = 3.5x10(7) M(-1) s(-1)), forming an intermediate selenium-nitrogen coupled zwitterionic radical with the positive charge at an intramolecularly formed Se(three-electron bond)N 2sigma/1sigma* three-electron bond, which is characterized by an optical absorption with lambda(max) at 375 nm, and a half-life of about 70 micros. The same transient is generated upon HO* radical-induced one-electron oxidation of selenomethionine (MetSe). This radical thus constitutes the redox intermediate between the two oxidation states, MetSeO and MetSe. Time-resolved optical data further indicate sulfur-selenium interactions between the Se(three-electron bond)N transient and GSH. The Se(three-electron bond)N transient appears to play a key role in the reduction of selenomethionine oxide by glutathione.

One-electron oxidation of ergothioneine and analogues investigated by pulse radiolysis: redox reaction involving ergothioneine and vitamin C.

Redox reactions of endogenous and exogenous sulphur-containing compounds are involved in protection against oxidative damage arising from the incidence and/or treatment of many diseases, including cancer. We have investigated, via pulse radiolysis, the one-electron oxidation of ergothioneine, a molecule with antioxidant properties which is detected at millimolar concentrations in certain tissues and fluids subject to oxidative stress, including erythrocytes and plasma. The spectrum of the transient species, assigned to the product of one-electron oxidation, observed after reaction of ergothioneine with the oxidizing radicals OH., N3. and CCl3O2. has a maximum absorption at 520 nm and is very similar to that obtained by oxidation of analogous molecules such as 2-mercaptoimidazole, 1-methyl-2-mercaptoimidazole, S-methyl- and S,N-dimethyl-ergothioneine. In the presence of vitamin C, the oxidized form of ergothioneine is repaired by a rapid reduction (k = 6.3 x 10(8) M(-1).s(-1)) producing ascorbyl radicals. This co-operative interaction between ergothionine and ascorbate, similar to that previously observed between vitamin E and ascorbate, may contribute to essential biological redox protection.

Free-radical repair by a novel perthiol: reversible hydrogen transfer and perthiyl radical formation.

2-(3-Aminopropyl-amino) ethaneperthiol (RSSH, the perthiol analogue of the thiol radioprotector, WR-1065) reacts with the alpha-hydroxy alkyl radical (CH3)2C.OH by donating a hydrogen atom as indicated by the characterization of perthiyl radicals (RSS.; lambda max approximately 374 nm, epsilon 374 approximately 1680 +/- 20 dm3 mol-1 cm-1) by pulse radiolysis. The perthiyl radical abstracts a hydrogen from the alcohol to establish a reversible hydrogen-transfer equilibrium. This equilibrium lies predominantly on the side of radical repair since the rate constants for the forward and reverse reactions at pH 4 are: kappa(RSSH+(CH3)2C.OH) = (2.4 +/- 0.1) x 10(9) dm3 mol-1 s-1 and kappa(RSS.+(CH3)2CHOH) = (3.8 +/- 0.3) x 10(3) dm3 mol-1 s-1 respectively. The pKa (RSSH<-->RSS(-)+H+) = 6.2 +/- 0.1 was determined from the pH dependence of the rate of perthiol repair. Identical experiments have been performed with WR-1065 allowing a direct comparison of free-radical repair reactivity to be made with the parthiol analogue. At pH approximately 7.4 the reactivities of the thiol and perthiol were similar, both repairing the alcohol radical with a rate constant of approximately (2.4 +/- 0.1) x 10(8) dm3 mol-1 s-1. However, at pH 5 whilst the hydrogen-donation rate of the thiol was 15-20% higher than at pH 7.4, the perthiol reactivity was over an order of magnitude higher. The thermodynamic driving force for the observed enhanced free-radical repair reactivity of RSSH compared to RSH is attributed to the resonance stabilization energy of 8.8 kJ mol-1 within the RSS. radical. These results indicate a possible application of RSSH/RSS- as DNA-targeted antioxidants or chemoprotectors.

Free radical reductive degradation of vic-dibromoalkanes and reaction of bromine atoms with polyunsaturated fatty acids: possible involvement of Br(.) in the 1,2-dibromoethane-induced lipid peroxidation.

Bromine atoms generated upon reductive degradation of 1,2-dibromoethane and various other vic-dibromoalkanes have been shown to react with polyunsaturated fatty acids via both abstraction of bisallylic hydrogen and addition to the double bonds. The abstraction process occurs with 53, 68, and 77% efficiency from linoleic (18:2), linolenic (18:3), and arachidonic acid (20:4), respectively. The corresponding absolute rate constants have been evaluated to be 1.2 x 10(9), 1.8 x 10(9), and 5.1 x 10(9) M-1 s-1 for these three polyunsaturated fatty acids (PUFAs). The rate constants for the bromine atom addition reaction appear to be very similar for all PUFAs and have been determined to (1.2 +/- 0.3) x 10(9) M-1 s-1. Absolute rate constants in the order of 10(5)-10(6) s-1 have also been measured for the bromine atom elimination from various beta-bromoalkyl radicals. The results render bromine atoms a potential initiator for lipid peroxidation, and their reactions may well provide an important chemical basis for the overall toxic action of 1,2-dibromoethane and related substrates.

Oxidation of polyunsaturated fatty acids and lipids through thiyl and sulfonyl radicals: reaction kinetics, and influence of oxygen and structure of thiyl radicals.

Thiyl free radicals have been shown to react with polyunsaturated fatty acids via abstraction of bisallylic hydrogen, forming pentadienyl radicals, and via addition to the double bonds. In the absence of oxygen, the latter pathway leads to regeneration of thiyl radicals through beta-elimination or "repair" of the adduct radicals by thiols. In the presence of oxygen, fixation of thiyl-induced damage occurs through reaction of O2 with the pentadienyl radical (yielding conjugated dienyl peroxyl radicals) and also with the thiyl-to-double bond adduct radical. A quantitative reaction scheme evaluated from these data considers abstraction, addition, rearrangement, and repair reactions, and the evaluation of rate constants for the individual steps. Absolute rate constants have been measured, in particular, for reactions of thiyl free radicals from glutathione, cysteine, homocysteine, N-acetylcysteine, cysteine ethyl ester, penicillamine, captopril, mercaptoethanol, and dithiothreitol with polyunsaturated fatty acids (PUFAs) ranging from 18:2 to 22:6, and the lipids trilinolein and trilinolenin. The rate constants for hydrogen abstraction were found to be typically of the order of 10(7) mol-1 dm3 s-1 and to increase with increasing lipophilicity of the attacking thiyl radical. Thioperoxyl radicals, RSOO., were found to be rather unreactive toward PUFAs, in contrast to the isomer sulfonyl radicals, RSO2., which not only abstract hydrogen from the bisallylic methylene groups of the PUFAs (although only at relatively small yield) but also readily add to the PUFA double bonds (major pathway). Specific information was obtained on the optical properties of the thiyl radical derived from the ACE inhibitor captopril, CpS. (lambda max = 340 nm, epsilon = 460 +/- 50 mol-1 dm3 cm-1), and its conjugate disulfide radical anion (CpS:.SCp) (lambda max = 420 nm).

Reactivity of ebselen and related selenoorganic compounds with 1,2-dichloroethane radical cations and halogenated peroxyl radicals.

The reactivity of ebselen, 2-phenyl-1,2-benzisoselenazol-3(2H)one, and structurally related analogues was studied by pulse radiolysis. The rate constant for the reaction of ebselen with trichloromethylperoxyl radicals was determined to be 2.9 X 10(8) M-1 s-1, while its sulfur analogue, 2-phenyl-1,2-benzisothiazol-3(2H)one, was oxidized at much lower rates, k less than or equal to 10(7) M-1 s-1. Among several derivatives studied, the only other compound that exhibited a high rate constant was 2-(methylseleno)-benzoic acid-N-phenylamide. Oxidation of ebselen by other halogenated peroxyl radicals was also carried out and revealed a direct relationship between rate constant and the degree of halogenation of the oxidant. The transient radicals generated during oxidation of ebselen and the analogues were characterized by optical absorption and conductivity measurements and were attributed to one-electron-oxidized radical cations. The oxidation potentials were determined by cyclic voltammetry. Comparative evaluation of the in vitro behavior during microsomal lipid peroxidation revealed ebselen to be the most potent antioxidant of the compounds investigated, 2-(Methylseleno)-benzoic acid-N-phenylamide, despite its high rate constant for oxidation by halogenated peroxyl radicals, was found to be a poor antioxidant. The rate constant of oxidation of ebselen by trichloromethylperoxyl radicals is comparable to that of alpha-tocopherol under similar conditions, underscoring the potential pharmacological interest of ebselen as an antioxidant.

Reaction of thiyl radicals with alcohols, ethers and polyunsaturated fatty acids: a possible role of thiyl free radicals in thiol mutagenesis?

Possible reactions of thiyl free radicals in biological environment are reviewed. In particular hydrogen transfer processes from model C-H compounds like alcohols and ethers as well as from polyunsaturated fatty acids to thiyl radicals are described to proceed with reasonably high rate constants (10(3)-10(4) and 10(6)-10(7) M-1 s-1, respectively). Thiyl radicals have thus to be considered as potentially hazardous species especially with respect to DNA damage and lipid peroxidation.

Thiyl radical attack on polyunsaturated fatty acids: a possible route to lipid peroxidation.

Absolute rate constants have been measured for the reaction of cysteinyl free radicals, CysS., with linoleic (18:2), linolenic (18:3) and arachidonic acid (20:4) in water/alcohol mixtures using the radiation chemical technique of pulse radiolysis. They are in the order of 10(6)-10(7) M-1 s-1 and increase with the number of biallylic functions, and with the polarity of the solvent. The reaction is shown to be a hydrogen atom abstraction from biallylic C-H bonds and yields pentadienyl radicals. The thiol mediated repair of the latter is considerably slower. Thiyl free radicals must consequently be considered as a potential source of lipid peroxidation.

Reversible H-atom abstraction from alcohols by thiyl radicals: determination of absolute rate constants by pulse radiolysis.

Penicillamine thiyl radicals, PenS., are shown to abstract hydrogen atoms from 2-propanol and to establish an equilibrium PenS. + (CH3)2 CHOH in equilibrium PenSH + (CH3)2 COH. The rate constants for the forward and back reaction have been determined to (1.4 +/- 0.3) x 10(4) and (1.2 +/- 0.3) x 10(8) M-1 s-1, respectively, by means of pulse radiolysis. The data have been obtained from various independent methods which include direct measurements and competitive schemes involving irreversible interception of the alcohol radical by electron acceptors (e.g. CCl4, PNAP) and/or the thiyl radical by antioxidants (e.g. alpha-tocopherol). The results demonstrate that the reaction of carbon-centered radicals with thiols, in radiation biology commonly known as "repair" reaction, may be reversed and thus imply the possibility of thiyl radical induced biological damage.

Rate constants for the reactions of halogenated organic radicals.

Absolute rate constants have been measured by means of pulse radiolysis for the reactions of various halogenated aliphatic compounds (ethane derivatives, including the anaesthetics halothane, enflurane, isoflurane and methoxyflurane) with hydrated electrons and .OH radicals, the reactions of halogenated carbon-centered radicals, derived thereby, with molecular oxygen, and the reactions of halogenated peroxyl radicals with various antioxidants (ascorbate, chlorpromazine, promethazine, propyl gallate, ABTS) in aqueous solutions. All oxygen addition reactions occur essentially diffusion-controlled. This finding is correlated with the stereoelectronic properties of the primary carbon-centred radicals. The oxidative power of the halogenated peroxyl radicals reflects the inductive -I effect of the halogens and accordingly increases with the degree of halogen substitution, with fluorine substituents being particularly effective. The peroxyl radicals derived from freon 113, namely CClF2CClFOO. and CCl2FCF2OO., have been identified as the best oxidants among these species.