RESUMEN
Tuberculosis (TB) is caused by Mycobacterium tuberculosis. TB is highly prevalent, characterized by the constant occurrence of drug-resistant cases, and confounded by the incidence of respiratory disease caused by non-tuberculous mycobacteria (NTB). Expanding the spectrum of drugs for the treatment of TB is indispensable. Loperamide, an antidiarrhoeal drug, enhances immune-driven antimycobacterial activity, and we aimed to evaluate its bactericidal activity against M. tuberculosis, Mycobacterium bovis BCG, Mycobacterium terrae and Mycobacterium smegmatis. Loperamide exhibited an inhibitory effect against all mycobacterial species tested, with MICs of 100 and 150 µg ml-1 . Thus, loperamide is a mycobactericidal drug with potential as adjunctive therapy for TB and NTB infections.
Asunto(s)
Antituberculosos/farmacología , Loperamida/farmacología , Mycobacterium bovis/efectos de los fármacos , Mycobacterium smegmatis/efectos de los fármacos , Mycobacterium tuberculosis/efectos de los fármacos , Micobacterias no Tuberculosas/efectos de los fármacos , Humanos , Pruebas de Sensibilidad Microbiana , Tuberculosis Pulmonar/tratamiento farmacológicoRESUMEN
In a previous paper by Cebrian et al. [Opt. Eng.53, 092006 (2014)OPEGAR0091-328610.1117/1.OE.53.9.092006], the knife-edge interferometer (KEI) was used for testing lenses with a collimated beam illuminating the lens. In this paper, a 2f scheme is used to test lenses, eliminating the use of a collimation beam, and testing, for the first time, concave reflecting (spherical and parabolic) surfaces at the center of curvature with KEI.
RESUMEN
AIM: In this study, we describe the isolation of a gene encoding a novel ß-fructofuranosidase from Bifidobacterium longum subsp. infantis ATCC 15697, and the characterization of the enzyme, the second one found in this strain, significantly different in primary sequence to the already reported bifidobacterial ß-fructofuranosidases. METHODS AND RESULTS: The gene, found through genome-mining was expressed in Escherichia coli C41(DE3). The recombinant enzyme (B.longum_l1) has a molecular weight of 75 kDa, with optimal activity at 50°C, pH 6·0-6·5, and a remarkable stability with a half-life of 75·5 h at 50°C. B.longum_l1 has a wide specificity for fructans, hydrolysing all substrates through an exo-type mechanism, including Oligofructose P95 (ß2-1 fructooligosaccharides (FOS), DP 2-8), Raftilose Synergy 1(ß2-1 FOS & inulin, DP 2-60), Raftiline HP (inulin, DP 2-60), bacterial inulin (3000 kDa) and levan (8·3 & 3500 kDa), Agave fructans (mixed fructans, DP 3-29) and levan-type FOS (ß2-6 FOS, DP 2-8), with the highest relative activity and turnover number found for levan-type FOS. The apparent affinity of the enzyme for levan-type FOS and Oligofructose P95 was found to be 9·2 and 4·6 mmol l(-1) (Km ) with a specific activity of 908 and 725 µmol min(-1) mg(-1) of protein (k2 ), respectively, more than twice the activity for sucrose. CONCLUSION: B.longum_l1 is a wide substrate specificity enzyme, which may contribute to the competitiveness and persistence of this strain in the colon. SIGNIFICANCE AND IMPACT OF THE STUDY: The bifidobacterial ß-fructofuranosidase activity was evaluated with a wide variety of substrates including noncommercial fructans, such as levan-type and mixed agave fructans. Its activity on these substrates certainly strengthens their commercial prebiotic character and contributes to the understanding of bifidobacteria stimulation by structurally diverse fructans.
Asunto(s)
Proteínas Bacterianas/metabolismo , Bifidobacterium longum subspecies infantis/enzimología , Fructanos/química , Fructanos/metabolismo , beta-Fructofuranosidasa/metabolismo , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Bifidobacterium longum subspecies infantis/genética , Bifidobacterium longum subspecies infantis/metabolismo , Peso Molecular , Oligosacáridos/química , Oligosacáridos/metabolismo , Especificidad por Sustrato , Sacarosa/metabolismo , beta-Fructofuranosidasa/química , beta-Fructofuranosidasa/genéticaRESUMEN
Resulting from impaired collagen turnover, fibrosis is a hallmark of adipose tissue (AT) dysfunction and obesity-associated insulin resistance (IR). Prolidase, also known as peptidase D (PEPD), plays a vital role in collagen turnover by degrading proline-containing dipeptides but its specific functional relevance in AT is unknown. Here we show that in human and mouse obesity, PEPD expression and activity decrease in AT, and PEPD is released into the systemic circulation, which promotes fibrosis and AT IR. Loss of the enzymatic function of PEPD by genetic ablation or pharmacological inhibition causes AT fibrosis in mice. In addition to its intracellular enzymatic role, secreted extracellular PEPD protein enhances macrophage and adipocyte fibro-inflammatory responses via EGFR signalling, thereby promoting AT fibrosis and IR. We further show that decreased prolidase activity is coupled with increased systemic levels of PEPD that act as a pathogenic trigger of AT fibrosis and IR. Thus, PEPD produced by macrophages might serve as a biomarker of AT fibro-inflammation and could represent a therapeutic target for AT fibrosis and obesity-associated IR and type 2 diabetes.
Asunto(s)
Diabetes Mellitus Tipo 2 , Resistencia a la Insulina , Tejido Adiposo/metabolismo , Animales , Diabetes Mellitus Tipo 2/metabolismo , Dipeptidasas , Fibrosis , Inflamación/metabolismo , Resistencia a la Insulina/genética , Macrófagos/metabolismo , Ratones , Obesidad/metabolismoRESUMEN
The application of an effective and ready-to-use tool for discovering clandestine graves is crucial for solving a number of cases where disappearance of people is involved. This is the case in Mexico, where the government drug war has resulted in a large number of missing people that has been estimated to be over 40,000 since the year 2006. In this article, we report results from an experimental study on simulated animal graves detection using several techniques from optical remote sensing. Results showed that several spectral indices from hyperspectral and/or multispectral sensors may be used to detect N-enriched vegetation. Thermal imagery was also effective to detect underground voids through differential thermography, although this was only effective for detecting large graves with bare terrain. Lastly, while dense pointclouds reconstructed from oblique aerial photography was able to detect vegetation regrowth over the pits, the terrain subsidence was not sufficiently large to be detected with this technique, even in the case of mechanical removal of vegetation.
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Entierro , Fotograbar , Tecnología de Sensores Remotos , Animales , Humanos , MéxicoRESUMEN
This study explores the effect of 229Th tracer tail interference on the determination of the sensitivity of 230Th alpha spectrometry of samples with environmental levels of radioactivity. Tracer peak tail interference was calculated with Suma-Alpha, whilst Visual Basic for Applications (VBA in Excel©) software was used to study the variation in sensitivity in terms of the amount of tracer added. Unnecessary increases in the amount of tracer or extended sample measuring times were observed to have adverse effects on method sensitivity (Detection Limit- Ld).
RESUMEN
Activation of protein-activated receptor (PAR-1) by thrombin potentiates the hyposmotic efflux of (3)H-D-aspartate and (3)H-taurine from cultured cerebellar astrocytes. This effect is mediated by a thrombin-elicited increase in cytosolic Ca(2+) levels [Ca(2+)](i) and the activation of phosphoinositide-3-kinase (PI3K). These signalling pathways operate independently showing additive effects if prevented simultaneously. The contribution of the Ca(2+)-mediated pathway to thrombin-increased D-aspartate or taurine efflux, evaluated by the inhibitory effect of preventing [Ca(2+)](i) rise, was higher for D-aspartate (64% efflux decrease) than for taurine (40% decrease). The PI3K blocker decreased 48% and 36% D-aspartate and taurine efflux, respectively. Hyposmolarity increases phosphorylation of EGFR and c-src, but thrombin did not enhance this effect. Blockade of EGFR/src phosphorylation marginally reduced (11-14%) the hyposmolarity plus thrombin efflux of D-aspartate; taurine efflux was more sensitive to these blockers (18-26%). Since thrombin has no effect increasing EGFR/src phosphorylation in astrocytes, the contribution of this transactivation pathway may represent the inhibition of the hyposmotic efflux solely.
Asunto(s)
Astrocitos/metabolismo , Ácido Glutámico/metabolismo , Transducción de Señal/fisiología , Taurina/metabolismo , Trombina/metabolismo , Animales , Astrocitos/citología , Calcio/metabolismo , Células Cultivadas , Receptores ErbB/metabolismo , Humanos , Concentración Osmolar , Fosfatidilinositol 3-Quinasas/metabolismo , Inhibidores de las Quinasa Fosfoinosítidos-3 , Familia-src Quinasas/metabolismoRESUMEN
BACKGROUND: fibrous dysplasia is characterized by the formation of fibrous tissue that generates immature malformed trabeculae. Their involvement may be monostotic or poliostotic. CASE REPORT: Thirty years old female with fibrous dysplasia of the left hip. At age 15 suffered hip fracture without apparent trauma, she was managed conservatively and significant shortening of the same limb was observed. At 30 years old, is pregnant, it had left hip pain, deformity and shortening is exacerbated. Simple radiography showed «shepherds crook deformity¼, she was treated with bisphosphonates. Computed axial tomography corroborates previous findings. She subsequently underwent subtrochanteric fracture fall with left hip dysplasia site, ground glass image of cystic appearance involving the femoral neck, trochanteric and subtrochanteric area. Tumor prosthesis of the left hip was implanted, four months evolution was favorable. CONCLUSION: Modular hip prosthesis system, reduces deformity, improves length and reduces pain in patients with resection of fibrous dysplasia of the hip.
ANTECEDENTES: La displasia fibrosa se caracteriza por la formación de tejido fibroso inmaduro que genera trabéculas mal formadas. Su afectación puede ser monostótica o poliostótica. CASO CLÍNICO: Femenino de 30 años con displasia fibrosa de cadera izquierda. A los 15 años sufre fractura de la misma cadera sin trauma aparente, manejada conservadoramente y con acortamiento importante de la misma extremidad. A los 30 años de edad se embaraza, presenta dolor en cadera izquierda y se exacerba la deformidad y el acortamiento. La radiografía simple muestra deformidad en «cayado de pastor¼, se manejó con bifosfonatos y la tomografía corrobora los hallazgos anteriores. Posteriormente sufrió caída con fractura subtrocantérica de cadera izquierda en sitio de displasia, imagen de vidrio despulido de apariencia quística que involucra el cuello femoral, zona trocantérica y subtrocantérica. Se colocó prótesis tumoral de cadera izquierda, a los cuatro meses mostró evolución favorable. CONCLUSIÓN: La prótesis tumoral femoral reduce la deformidad, mejora la longitud y disminuye el dolor en pacientes con resección de displasia fibrosa de cadera.
Asunto(s)
Artroplastia de Reemplazo de Cadera , Displasia Fibrosa Ósea , Prótesis de Cadera , Neoplasias , Adulto , Femenino , Fémur , Displasia Fibrosa Ósea/cirugía , Humanos , RadiografíaRESUMEN
OBJECTIVE: To determine the size and clinical features of the optical disc in healthy term infants. METHODOLOGY: Descriptive, observational, cross-sectional, and retrospective study based on complete medical records of newborns at the Angeles Pedregal Hospital, Mexico DF, from May to August 2015. The measurements of the optical disc and clinical features were obtained from digital photographs and evaluated by 2experts. Frequencies, means and standard deviation were calculated using the SPSS version 17.0 for Windows. RESULTS: The study included a total of 121 patients and 121 eyes. There were 65 males. The mean vertical diameter was 1.60±0.17mm, horizontal diameter 1.31±0.13mm, optical disc area 1.43±0.26mm2, and cup to disc ratio 0.25±0.11. The neuroretinal ring colour was orange in 116 (95.9%) eyes. The cribriform plate was not visible in any patient, and in 90 (74.4%) eyes the appearance of the vessels in the papilla was central, and nasal in the rest. The cilioretinal artery was present in 38 (31.4%) eyes. A hyper- and hypo-pigmented peripapillary ring was observed in 114 eyes (94.2%). CONCLUSION: The mean area of the optic nerve is 1.43±0.26mm2, slightly higher than previously reported. The mean cup to disc ratio is less than 0.3, as reported in the literature, and it is noteworthy that all eyes have a hyper-pigmented and hypo-pigmented peripapillary ring.
Asunto(s)
Disco Óptico/anatomía & histología , Antropometría , Estudios Transversales , Femenino , Humanos , Recién Nacido , Masculino , México , Valores de Referencia , Estudios RetrospectivosRESUMEN
Irradiation at 334 and 365 nm of a highly purified preparation of thymine-labeled transforming DNA from Haemophilus influenzae produced a photo product containing label from thymine but different from the cyclobutane dimer. The photoproduct is soluble in water and in ethanol and Rf values in a number of solvents are presented. The photoproduct has properties similar in a number of respects to those of the spore photoproduct, 5-thyminyl-5,6-dihydrothymine. The near ultraviolet photoproduct is more likely to affect the oxygen independent inactivation of transforming DNA rather than its mutagenesis, as judged by the quantitative relationship between amount of photboproduct and inactivation and mutagenesis.
Asunto(s)
ADN Bacteriano/efectos de la radiación , Haemophilus influenzae/metabolismo , Timina , Transformación Genética , Rayos Ultravioleta , Cromatografía en Papel , ADN Bacteriano/metabolismo , Haemophilus influenzae/efectos de la radiación , Mutación , Transformación Genética/efectos de la radiaciónRESUMEN
INTRODUCTION: Osteoarthritis is a degenerative joint disease that modifies the mechanical and biological properties of articular cartilage and subchondral bone, treatment is aimed at relieving pain, maintain joint and reduce disease progression function. The aim of this paper is to compare the surgical outcomes of the arthroscopic articular cleaning and Bandi procedure by using the WOMAC scale. METHODS: Cross-sectional study, functional outcome of treatment of patellofemoral ostheoarthritis by arthroscopic articular cleaning and Bandi procedure are compared. Variables were gender, age, affected side, surgical technique and preoperative and 12 months follow up WOMAC evaluation. We used descriptive statistics and t-test for mean difference in WOMAC between both groups of patients. RESULTS: n = 37 patients, the mean age was 53.48 (28-82), ± 12.55 years; 11 (29.7%) males and 26 (70.3%) women, the affected side: 19 (51.35%) right and 18 (48.65%) left. SURGICAL TECHNIQUE: 45.9% arthroscopic articular cleaning and 54.1% Bandi procedure. Patients operated by both technics: Bandi and arthroscopic articular cleaning had improvement in pain, stiffness and physical function (p = 0.00); comparison of global WOMAC score for both techniques a year after showed no statistically significant differences (p = 0.78). CONCLUSION: Both techniques (Bandi and arthroscopic articular cleaning) offer good results at 365 days of surgery, however patients managed by arthroscopic articular cleaning have less pain compared with Bandi procedure.
INTRODUCCIÓN: La osteoartritis (OA) es una artropatía degenerativa que modifica las propiedades mecánicas y biológicas, del cartílago articular y del hueso subcondral, su tratamiento va encaminado hacia el alivio del dolor, mantener la función articular y reducir la progresión de la enfermedad. El objetivo de este trabajo es comparar los resultados quirúrgicos de la limpieza articular artroscópica y adelantamiento rotuliano utilizando la escala WOMAC. METODOLOGÍA: Estudio transversal en el que se compara el resultado funcional del tratamiento de la OA patelofemoral en pacientes operados por limpieza articular artroscópica y pacientes operados por adelantamiento rotuliano con técnica de Bandi. Las variables fueron, género, edad, lado afectado, técnica quirúrgica e índice de WOMAC prequirúrgico y a los 12 meses de seguimiento. Utilizamos estadística descriptiva así como t de Student para la diferencia de promedios de WOMAC entre ambos grupos de pacientes. RESULTADOS: n = 37 pacientes, la edad promedio fue 53.48 años (28-82), ± 12.55, el género 11 (29.7%) hombres y 26 (70.3%) mujeres, el lado afectado: 19 (51.35%) derecho y 18 (48.65%) izquierdo. Técnica quirúrgica: 45.9% artroscópico y 54.1% con técnica de Bandi. Los pacientes operados mediante Bandi y adelantamiento rotuliano tuvieron mejoría del dolor, rigidez articular y de la función física (p = 0.00); la comparación del puntaje global de WOMAC para ambas técnicas al año no mostró diferencias estadísticamente significativas (p = 0.78). CONCLUSIÓN: Ambas técnicas (Bandi y limpieza artroscópica) ofrecen buenos resultados a los 365 días de operados, sin embargo, los pacientes manejados por limpieza artroscópica presentan menor dolor comparados con los de adelantamiento rotuliano tipo Bandi.
RESUMEN
Ischemia/reperfusion of organs and cells induces apoptosis through a complicated series of changes in mitochondria, mainly the generation of oxygen free radicals, permeability transitions, calcium translocations, and release of apoptogenic factors such as cytochrome c and Bcl-2 family members. The liberation of these factors occurs very early after reoxygenation and it has been assumed that it takes place without any structural alteration of the mitochondrial membranes. The aim of this study was to detect ultrastructural changes of mitochondria in the initial stages of reperfusion at the time when Bcl-2 and succinic dehydrogenase, located in the outer and inner membranes, respectively, were released. Ischemia/reperfusion was produced in adult rats by clamping one renal artery for 60 min and reoxygenating for 60, 120, 180, and 240 min. A model of chemical hypoxia with intra-arterial 50 mM sodium azide served as comparison, allowing free blood flow for 30, 60, 120 and 180 min. Light and electron microscopy, immunostaining for Bcl-2, and enzyme histochemistry for succinic dehydrogenase were performed. Our results showed mitochondrial swelling, rupture of inner and outer membranes, and leakage of mitochondrial matrix into the cytoplasm in ischemia after 120 min of reperfusion. Bcl-2 immunoreactivity and focal lowering of SDH reactivity were also noted and became more pronounced at the same time that the mitochondrial ultrastructure demonstrated more evident changes including rupture of the inner and outer membranes. Our studies seem to indicate that in early ischemia-reperfusion and in chemical hypoxia-induced apoptosis, the earliest ultrastructural changes take place in mitochondria and that swelling and rupture of mitochondrial membranes occur in parallel with the loss of Bcl-2 and SDH activity.
Asunto(s)
Apoptosis/fisiología , Riñón/ultraestructura , Mitocondrias/fisiología , Mitocondrias/ultraestructura , Daño por Reperfusión/patología , Animales , Hipoxia de la Célula , Membranas Intracelulares/ultraestructura , Riñón/irrigación sanguínea , Riñón/fisiología , Masculino , Microscopía Electrónica , Dilatación Mitocondrial , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Ratas , Ratas Sprague-Dawley , Daño por Reperfusión/fisiopatología , Succinato Deshidrogenasa/metabolismoRESUMEN
Haemophilus influenzae has been inactivated anaerobically at 313, 334, 365 and 405 nm, and exhibits the greatest sensitivity at 334 nm. The rec1 and uvr1 mutants show the greatest increase in sensitivity over the wild-type at 313 nm, but differences could be seen also at the other wavelengths. Anaerobic irradiation is less effective for killing at all the wavelengths than irradiation under aerobic conditions, but the greatest difference was observed at 365 nm. No induced mutation was seen as a result of anaerobic irradiation at 334 nm, although purified transforming DNA can be mutated at this wavelength.
Asunto(s)
Reparación del ADN , Haemophilus influenzae/genética , ADN Bacteriano/efectos de la radiación , Relación Dosis-Respuesta en la Radiación , Haemophilus influenzae/efectos de la radiación , Mutación , Consumo de Oxígeno , Transformación Genética , Rayos UltravioletaRESUMEN
The lethal effect of polychromatic near-UV light (325-400 nm) on Haemophilus influenzae was 8 times higher under aerobic than anaerobic irradiation. This light increased the frequency of mutation to novobiocin resistance and ability to utilize protoporphyrin IX. The slope of mutagenic effect at low doses appeared greater for the aerobic than for the anaerobic group. We concluded that polychromatic near-UV mutation of H. influenzae under anaerobic irradiation was caused by direct oxygen-independent action on DNA.
Asunto(s)
Haemophilus influenzae/efectos de la radiación , Rayos Ultravioleta , Farmacorresistencia Microbiana , Haemophilus influenzae/genética , Haemophilus influenzae/metabolismo , Pruebas de Mutagenicidad , Novobiocina/metabolismoRESUMEN
Mutations were produced in purified transforming DNA from Haemophilus influenzae by near-UV radiation and were assayed as mutants among cells transformed with irradiated DNA. The maximum efficiency of mutation induction was at around 334 nm, and the efficiency dropped off steeply at lower and higher wavelengths. The difference between the action spectrum for mutation and that for the oxygen-independent inactivation of transforming DNA, which had a shoulder at 365 nm, indicates that there are different lesions involved in the inactivating and mutagenic effects of near-UV. The presence of histidine during irradiation enhanced the mutagenic effect at 334 and 365 nm, although it protected against inactivation at 365 nm. The effective near-UV wavelengths for in vitro mutation are to some extent the same as the effective wavelengths for mutation in vivo reported previously. These findings indicate that mutations are produced in vivo by near-UV with DNA as the primary target molecule rather than by a secondary non-photochemical reaction between DNA and some other cell component.
Asunto(s)
Haemophilus influenzae/genética , Haemophilus influenzae/efectos de la radiación , Mutagénesis , Rayos Ultravioleta , ADN Bacteriano/genética , ADN Bacteriano/efectos de la radiación , Luz , Consumo de Oxígeno/efectos de la radiaciónRESUMEN
Our previous work has demonstrated that whereas near-UV radiation is not a mutagen for Haemophilus influenzae cells, it does induce mutations in purified transforming DNA. In order to test various hypotheses concerning this difference, we have irradiated cells at 334 and 365 nm, then lysed them and assayed the DNA for induced mutations and for inactivation of transforming ability. The inactivation was only a little lower than observed with highly purified transforming DNA. The DNA irradiated in vivo was mutated at both wavelengths, but with considerably lower efficiency than was purified DNA. Neither incubation of the cells after irradiation and before lysis nor freezing and thawing the cells significantly changed the amount of mutation. It is concluded that there is some protection of the DNA against premutational lesions by the in vivo environment, but that it is not enough to account for the total lack of mutation of the cells. A probable explanation of this lack of cell mutation is that lethal lesions in the cells are induced much more readily than premutational lesions.
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ADN Bacteriano/efectos de la radiación , Haemophilus influenzae/genética , Transformación Bacteriana , Relación Dosis-Respuesta en la Radiación , Farmacorresistencia Microbiana , Mutación , Novobiocina/farmacología , Fenotipo , Rayos UltravioletaRESUMEN
Mutation and inactivation of H. influenzae have been measured following irradiation at various near-UV wavelengths. Inactivation takes place most readily at 334 nm (but is unaffected by absence of excision or postreplication repair), and decreases markedly at longer wavelengths. No induced mutations to resistance to novobiocin or streptomycin or to ability to utilize protoporphyrin instead of hemin were detected at any of the wavelengths used. There were also no detectable induced mutations in an excision-defective strain after 334-nm irradiation. These results are in contrast to the in vitro mutation of purified transforming DNA we previously observed.
Asunto(s)
Reparación del ADN/efectos de la radiación , Haemophilus influenzae/genética , Mutación , Relación Dosis-Respuesta en la Radiación , Haemophilus influenzae/efectos de la radiación , Rayos UltravioletaRESUMEN
Previous studies have shown the non-mutability of Haemophilus influenzae either by UV irradiation of the cells or by irradiating the transforming DNA and transformation of competent cells. In the present work, we present evidence of transforming DNA mutation in vitro by UV irradiation at -70 degrees C, which upon transformation of competent cells showed a rise in the mutation frequencies of novobiocin resistance of the order of several hundredfold. Also we performed experiments using the UV-irradiated DNA either sonicated or DNase-treated, which allowed us to propose that such rise in mutation frequency is probably due to the integration of DNA carrying premutagenic photoproducts to the recipient cells' genome. We think that the key point was the low temperature at which the DNA was irradiated in order to obtain the mutagenic effects, since it is likely that at -70 degrees C, the main photoproducts are not the cyclobutane dimers, but are the spore photoproducts, which are probably responsible for the damage that leads to mutagenic effects.
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ADN Bacteriano/genética , Haemophilus influenzae/efectos de la radiación , Mutagénesis , Transformación Bacteriana , Rayos Ultravioleta , Frío , Desoxirribonucleasas/farmacología , Farmacorresistencia Microbiana/genética , Haemophilus influenzae/genética , Novobiocina/farmacología , Sonicación , Esporas Bacterianas , Timina/análogos & derivados , Timina/metabolismoRESUMEN
A plasmid called pMucA, from a piece of the plasmid pKM101 (Mol. Gen. Genet 167 (1979) 317) cloned in the vector pDM2 (J. Bacteriol. 151 (1982) 1605), caused higher mutation in a local region of Haemophilus influenzae and caused even more mutation there in a strain also containing novC, the latter causing an increase in supercoiling (J. Bacteriol 164 (1985) 525). The novD mutation depressed supercoiling, and also depressed the mutation by pMucA in the local region of the chromosome. Thus, it is clear that supercoiling is an important phenomenon in spontaneous mutation of H. influenzae. The pMucA plasmid caused a number of other phenomena in H. influenzae, induced UV mutation (Proc. Natl. Acad. Sci. USA 82 (1985) 7753), decreased UV sensitivity of transforming DNA, but not cells, and UV-induced recombination of mutants of phage HP1c1. The effect of the MucA protein in mutagenesis of H. influenzae we consider to be due to the introduction of some of the E. coli functions from pKM101. We postulate that the localized mutation caused by the MucA plasmid also involved localization of the plasmid or its coded protein in the same area, resulting from binding to a homologous gene, probably rec-1, very close to the localized region.
Asunto(s)
Proteínas Bacterianas/fisiología , ADN Bacteriano/genética , Haemophilus influenzae/genética , Proteínas Bacterianas/genética , Bacteriófagos/genética , Bacteriófagos/efectos de la radiación , Mapeo Cromosómico , Cromosomas Bacterianos/genética , ADN-Topoisomerasas de Tipo II/genética , ADN Superhelicoidal/genética , Relación Dosis-Respuesta en la Radiación , Farmacorresistencia Microbiana/genética , Orden Génico , Ligamiento Genético , Haemophilus influenzae/efectos de los fármacos , Haemophilus influenzae/efectos de la radiación , Resistencia a la Kanamicina/genética , Mutación , Novobiocina/farmacología , Plásmidos/efectos de los fármacos , Plásmidos/genética , Plásmidos/efectos de la radiación , Recombinación Genética/efectos de la radiación , Rayos UltravioletaRESUMEN
Spontaneous mutation was greatly increased in a localized region of the chromosome of Haemophilus influenzae, but not at other loci, by a nov gene mutation called novC that increased DNA supercoiling. Another nov gene mutation, called novD, decreased spontaneous mutation in the same localized region and depressed DNA supercoiling. Both mutations, which code for the gyrase B subunit, have been cloned, and the cloned versions also altered mutagenesis and supercoiling in a similar fashion as the two mutations on the chromosome, although novC on the plasmid caused somewhat less mutation than on the chromosome. We postulate that the effects of the gyrase B mutations on the chromosome result from their effects on supercoiling because of increased gyrase near its site of production. The fact that the novC on a plasmid does not cause mutagenesis except in the same localized region that is altered by this mutation on the chromosome, is difficult to explain. One possibility is that there is a complex of proteins in this region which is necessary for the effects on supercoiling and thus, also on mutagenesis.