RESUMEN
Surgical site infections (SSI) are a significant cause of post-surgical morbidity and mortality. The objectives of this study were to determine the prevalence of SSI and identify risk factors for infections following cesarean section (CS). A prospective study of SSI after CS was carried out from January 2014 to December 2016 using the methodology of the American National Nosocomial Infection Surveillance System. Suspected SSIs were confirmed clinically by the surgeon, and or, by culture. Seven thousand two hundred thirty five CS were performed with an overall SSI prevalence of 2.1%, increasing from 1.7% in 2014 to 2.95% in 2016 (P = 0.010). Of 152 cases of SSI, the prevalence of infection was 46.7% in women ⩽30 years and 53.3% in women >30 years (P = 0.119). Of 148 culture samples from as many women, 112 (75.7%) yielded growth of microorganisms with 42 (37.5%) of isolates being multi-drug resistant (MDR). Women who did not receive prophylactic antibiotics (35.5%) developed SSI more often than those who did (P < 0.0001). These findings suggest that emergency CS and inappropriate antibiotic prophylaxis are risk factors for developing SSI. In the light of the emergence of MDR bacteria there is a need to implement revised prophylactic antibiotic policy as part of antimicrobial stewardship to decrease SSI rates.
Asunto(s)
Cesárea/efectos adversos , Hospitales Generales , Infección de la Herida Quirúrgica/epidemiología , Adulto , Femenino , Humanos , Kuwait/epidemiología , Prevalencia , Estudios Prospectivos , Factores de Riesgo , Adulto JovenRESUMEN
A nanoscopic exploratory measurement technique to measure voltage distribution across an operating semiconductor device in cryogenic temperature has been developed and established. The cross-section surface of the terahertz (THz) quantum cascade laser (QCL) has been measured that resolves the voltage distribution at nanometer scales. The electric field dissemination across the active region of the device has been attained under the device's lasing conditions at cryogenic temperature of 77 K.
RESUMEN
OBJECTIVE: To assess the quality of maternity care in an Indian metropolitan city. STUDY DESIGN: Three-stage cluster randomised cross-sectional survey. SETTING: Sixty selected colonies of Delhi. POPULATION: One thousand eight hundred and one subjects (of 2286 eligible) were enrolled from 118 446 houses. Women who had delivered a live viable birth in the past 6 months were selected for the study. METHODS: In stage 1, 20 wards (of 150) were selected using a probability-proportionate-to-size systematic method. In stage 2, one colony from each income stratum (high, middle and low) was selected from each ward by simple random sampling. In stage 3, a house-to-house survey was conducted to recruit 30 women for administering a peer-reviewed and pilot-trialled questionnaire. MAIN OUTCOME MEASURES: Caesarean section rate, induction rate and episiotomy rate. RESULTS: National health targets such as iron supplementation advice (>96%), tetanus vaccination (>81%), and ≥3 antenatal visits (>90%) were largely achieved across health care facilities but not in home deliveries. Interventions were lower in public than private hospitals: caesarean section [23.7% (20.2-27.7) versus 53.8% (49.3-58.3)], induction [20.6% (17.5-24.25) versus 30.8% (26.8-33.2)] and episiotomy [57.8% (52.3-63.1) versus 79.4% (71.0-85.9)]. Private hospitals achieved better labour support rates [1.1% (0.5-2.2) versus 14.6% (8.5-24.1)] and pain relief [0.9% (0.4-2.0) versus 9.9 (6.5-14.8)]. Pubic hair shaving [16.2% (11.5-22.5) versus 36.4% (29.9-43.4)], enema [20.2% (15.5-26.0) versus 57.3% (49.5-64.8)], and IV fluids during labour [44.0% (36.2-52.2) versus 38.7% (29.3-49.1)] were widely prevalent in public and private hospitals. CONCLUSION: Present practices fall short of evidence-based guidelines, with relative overuse of interventions in private hospitals and deficiency of patient-centred practices such as labour support in public hospitals.
Asunto(s)
Adhesión a Directriz/estadística & datos numéricos , Hospitales Privados/normas , Hospitales Públicos/normas , Servicios Urbanos de Salud/normas , Adulto , Cesárea/estadística & datos numéricos , Estudios Transversales , Enema/estadística & datos numéricos , Episiotomía/estadística & datos numéricos , Medicina Basada en la Evidencia , Femenino , Fluidoterapia/estadística & datos numéricos , Encuestas de Atención de la Salud , Parto Domiciliario/normas , Parto Domiciliario/estadística & datos numéricos , Hospitales Privados/estadística & datos numéricos , Hospitales Públicos/estadística & datos numéricos , Humanos , India , Trabajo de Parto Inducido/estadística & datos numéricos , Trabajo de Parto , Manejo del Dolor/estadística & datos numéricos , Atención Perinatal/normas , Atención Perinatal/estadística & datos numéricos , Guías de Práctica Clínica como Asunto , Embarazo , Atención Prenatal/normas , Atención Prenatal/estadística & datos numéricos , Ultrasonografía Prenatal/estadística & datos numéricos , Servicios Urbanos de Salud/estadística & datos numéricos , Adulto JovenRESUMEN
BACKGROUND: Reference values of peak expiratory flow (PEF) in Indian adults have to date been derived locally, using an old (Wright) scale peak flow meter. There are thus no reliable reference values for PEF for Indians and this formed the aim of the study. MATERIALS AND METHODS: A European Union (EU) scale peak flow meter (PFM) was used for the study. A respiratory health and demographic questionnaire was administered to 1000 male and female adults from randomly selected locations in the country in this multi centric study. The locations represented different geographic, ethnic, and socioeconomic backgrounds. Patients were stratified according to height and age. The PEF values were measured using the Breathometer™ (Cipla Ltd., India) with EU scale. Reference equations were derived from multiple regression analysis. RESULTS: A total of 3608 participants were excluded. In 80% of the remaining 6138 healthy adults (M: 3720; F: 2418), the predicted regression equations were derived. Gender, age, and height were the significant determinants of PEF. The equations in L/minute are: Females: PEF = -1.454 (Age) + 2.368 (Height) Males: PEF = -1.807 (Age) + 3.206 (Height). The derived equation was validated by comparing the predicted PEF values with the measured values in the remaining sample of 20% (Mean ΔPEF: M = 1.85 L/minute, CI = -2.76, 6.47; F = 1.64, CI = -2.89, 6.18). An Indian adult with average height and age was found to have approximately 30% lower PEF compared to the corresponding European adult using the Nunn and Gregg equation. CONCLUSION: We derived reference values of PEF for Indian adults using a validated EU scale peak flow meter.
Asunto(s)
Ápice del Flujo Espiratorio , Pruebas de Función Respiratoria/instrumentación , Adulto , Factores de Edad , Pueblo Asiatico , Estatura , Femenino , Humanos , India , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Valores de Referencia , Análisis de Regresión , Pruebas de Función Respiratoria/estadística & datos numéricos , Sensibilidad y Especificidad , Factores Sexuales , Encuestas y CuestionariosRESUMEN
The distribution of charge carriers inside the active region of a terahertz (THz) quantum cascade laser (QCL) has been measured with scanning spreading resistance microscopy (SSRM) and scanning capacitance microscopy (SCM). Individual quantum well-barrier modules with a 35.7-nm single module thickness in the active region of the device have been resolved for the first time using high-resolution SSRM and SCM techniques at room temperature. SSRM and SCM measurements on the quantum well-barrier structure were calibrated utilizing known GaAs dopant staircase samples. Doping concentrations derived from SSRM and SCM measurements were found to be in quantitative agreement with the designed average doping values of the n-type active region in the terahertz quantum cascade laser. The secondary ion mass spectroscopy provides a partial picture of internal device parameters, and we have demonstrated with our results the efficacy of uniting calibrated SSRM and SCM to delineate quantitatively the transverse cross-sectional structure of complex two-dimensional terahertz quantum cascade laser devices.
RESUMEN
Most laboratory evolution studies that characterize evolutionary adaptation genomically focus on genetically simple traits that can be altered by one or few mutations. Such traits are important, but they are few compared with complex, polygenic traits influenced by many genes. We know much less about complex traits, and about the changes that occur in the genome and in gene expression during their evolutionary adaptation. Salt stress tolerance is such a trait. It is especially attractive for evolutionary studies, because the physiological response to salt stress is well-characterized on the molecular and transcriptome level. This provides a unique opportunity to compare evolutionary adaptation and physiological adaptation to salt stress. The yeast Saccharomyces cerevisiae is a good model system to study salt stress tolerance, because it contains several highly conserved pathways that mediate the salt stress response. We evolved three replicate lines of yeast under continuous salt (NaCl) stress for 300 generations. All three lines evolved faster growth rate in high salt conditions than their ancestor. In these lines, we studied gene expression changes through microarray analysis and genetic changes through next generation population sequencing. We found two principal kinds of gene expression changes, changes in basal expression (82 genes) and changes in regulation (62 genes). The genes that change their expression involve several well-known physiological stress-response genes, including CTT1, MSN4 and HLR1. Next generation sequencing revealed only one high-frequency single-nucleotide change, in the gene MOT2, that caused increased fitness when introduced into the ancestral strain. Analysis of DNA content per cell revealed ploidy increases in all the three lines. Our observations suggest that evolutionary adaptation of yeast to salt stress is associated with genome size increase and modest expression changes in several genes.
Asunto(s)
Adaptación Biológica , Evolución Biológica , Saccharomyces cerevisiae/genética , Salinidad , Cloruro de Sodio/farmacología , Electroforesis en Gel de Campo Pulsado , Amplificación de Genes , Eliminación de Gen , Duplicación de Gen , Perfilación de la Expresión Génica , Regulación Fúngica de la Expresión Génica , Genes Fúngicos , Ploidias , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/efectos de los fármacos , Análisis de Secuencia de ADNRESUMEN
The mode of presentation of coeliac disease has been changing to more atypical or silent disease. Few studies described the clinical presentation of adult coeliac disease in Ireland in recent years. We retrospectively collected the clinical data for all patients who had a diagnosis of coeliac disease made in our centre between January 07 and December 08. Forty seven adults, predominantly females (n = 30), had a confirmed diagnosis of coeliac disease made during the study period. In our patient cohort, the presenting symptom was diarrhoea in 19 (40%) patients, while 16 patients (34%) did not have any G.I. symptoms, 10 (21%) presented with anaemia. Females presented at a significantly younger age compared to males, with median ages at diagnosis of 44.5 and 57 years, respectively (p = 0.04). Females also presented more commonly with non G.I. symptoms (p = 0.07). The reasons behind this gender difference need further study.
Asunto(s)
Enfermedad Celíaca/diagnóstico , Adulto , Índice de Masa Corporal , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Transglutaminasas/análisis , Pérdida de PesoRESUMEN
BACKGROUND: Despite guidelines recommending inhalation therapy as the preferred choice, oral therapy is still widely used in the treatment of asthma in India. However, data about the level of asthma control and healthcare use in patients on oral anti-asthma medications are scarce.METHODS: A retrospective study was conducted to assess the level of asthma control and healthcare use in patients taking oral anti-asthma medications.RESULTS: The study population consisted of 381 adults randomly selected from health screening programmes. All subjects were already receiving oral anti-asthma medications; however, up to 72% had not been diagnosed with asthma by their treating doctors prior to the screening programmes. The cohort had a mean age of 48.26 ± 13.83 years (70% males) and mean peak expiratory flow of 245 ± 78.93 mL/sec. The mean Asthma Control Questionnaire 5 (ACQ-5) score was 2.53 ± 1.15, with respectively 33%, 49.3% and 32.6% reporting at least one episode of breathlessness, one emergency doctor visit and one hospitalisation due to asthma or its symptoms in the past year.CONCLUSION: Underdiagnosis and inappropriate management, as indicated by the poor asthma control and increased hospitalisations seen in this study, is probably a key contributor to the increased burden of the disease in India.
Asunto(s)
Antiasmáticos , Asma , Adulto , Antiasmáticos/uso terapéutico , Asma/diagnóstico , Asma/tratamiento farmacológico , Estudios de Cohortes , Progresión de la Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios RetrospectivosRESUMEN
INTRODUCTION: Many studies looked at outcomes and risk factors in laparoscopic cholecystectomies in general, including a few studies on risk factors and scoring systems in predicting conversion to open surgery. Little data has been produced on high-risk patients undergoing cholecystectomy. Identifying risk factors in this group could help stratify decision making regarding best management strategies.The aim of this study was to investigate outcomes of laparoscopic cholecystectomies in patients with ASA 3 and 4. METHODS: Data was collected and collated from a prospectively maintained database of all laparoscopic cholecystectomies performed by 13 general surgeons in a single unit. Case notes were reviewed for all patients with ASA 3 and 4 between 2013 and 2017. Data analysis was performed using R studio v 3.4. RESULTS: 244 cases were reviewed. Common bile duct was dilated in 52 cases (21.31%). Gall bladder wall was thick in 102 (41.8%) of the patients. Surgery was elective in 203 (83.2%) of the patients. ERCP was performed in 41 (16.9%) of the patients prior to surgery. 150 patients (62.2%) stayed for 1 day while 36 (14.9%) stayed for 2 days and the remaining 55 (22.9%) stayed for 3 days or more. Complications occurred in 37 (15.16%) of the patients while 23 (9.43%) of the patients were readmitted. 7 patients (2.87%) returned to theatre and 8 (3.28%) stayed in ITU post-op. Two patients died (0.82%). CONCLUSION: Laparoscopic cholecystectomies in higher risk populations are safe. Alternative methods such as cholecystostomy and ERCP may be of benefit in these patients.
RESUMEN
BACKGROUND: Chronic obstructive pulmonary disease (COPD) is common among non-smokers exposed to solid fuel combustion at home. Different clinical characteristics in these patients may have significant therapeutic and prognostic implications.METHODS: We used medical record review and a questionnaire among COPD patients at 15 centres across India to capture data on demographic details, different types of exposures and clinical characteristics. Chest radiography and pulmonary function testing were performed in all 1984 cases; C-reactive protein and exhaled breath nitric oxide were measured wherever available.RESULTS: There were 1388 current or ex-smokers and 596 (30.0%) non-smokers who included 259 (43.5%) male and 337 (56.5%) female patients. Sputum production was significantly more common in smokers with COPD (P < 0.05). The frequency of acute symptomatic worsening, emergency visits and hospitalisation were significantly higher (P < 0.05) in non-smokers with COPD; however, intensive care unit admissions were similar in the two groups. There was no significant difference with respect to the use of bronchodilators, inhalational steroids or home nebulisation among smoker and non-smoker patients. The mean predicted forced expiratory volume in 1 sec in smokers (43.1%) was significantly lower than in non-smokers (46.5%).CONCLUSION: Non-smoker COPD, more commonly observed in women exposed to biomass fuels, was characterised by higher rate of exacerbations and higher healthcare resource utilisation.
Asunto(s)
No Fumadores , Enfermedad Pulmonar Obstructiva Crónica , Broncodilatadores/uso terapéutico , Femenino , Volumen Espiratorio Forzado , Humanos , India/epidemiología , Masculino , Enfermedad Pulmonar Obstructiva Crónica/diagnóstico , Enfermedad Pulmonar Obstructiva Crónica/tratamiento farmacológico , Enfermedad Pulmonar Obstructiva Crónica/epidemiologíaRESUMEN
The c-ras1H oncogene can be distinguished from its normal cellular counterpart by the loss of a restriction endonuclease site. This sequence alteration is the basis of a rapid screening method for the presence of this oncogene. DNA's from 34 individuals were screened by this method, and all were homozygous for the normal allele. In contrast, DNA from a patient's bladder tumor, as well as DNA from his normal bladder and leukocytes, were heterozygous at that restriction endonuclease site. Further restriction enzyme mapping pinpointed the change in the mutant allele as being one of two nucleotides, either of which would change the 12th amino acid (glycine) in the normal c-ras1H gene product. Point mutations in the codon for this amino acid have previously been described in a bladder tumor cell line and in the viral oncogene v-rasH. These results indicate that the patient carried a c-ras1H oncogene in his germ line, raising the possibility that the c-ras1H oncogene confers a predisposition to neoplasia.
Asunto(s)
Oncogenes , Neoplasias de la Vejiga Urinaria/genética , Secuencia de Bases , Transformación Celular Neoplásica/patología , Humanos , MutaciónRESUMEN
Harvey murine sarcoma virus is a retrovirus which transforms cells by means of a single virally encoded protein called p21 has. We have determined the nucleotide sequence of 1.0 kilobase in the 5' half of the viral genome which encompasses the has coding sequences and its associated regulatory signals. The nucleotide sequence has identified the amino acid sequence of two additional overlapping polypeptides which share their reading frames and the carboxyl termini with p21 but which contain additional NH2-terminal amino acids.
Asunto(s)
Virus Defectuosos/genética , Virus del Sarcoma Murino/genética , Proteínas Virales/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Transformación Celular Viral , Células Cultivadas , Genes Virales , Proteína Oncogénica p21(ras) , Fragmentos de Péptidos , Biosíntesis de Proteínas , Conformación Proteica , ARN Viral/genética , Proteínas Virales/análisisRESUMEN
The nucleotide sequence of SV40 DNA was determined, and the sequence was correlated with known genes of the virus and with the structure of viral messenger RNA's. There is a limited overlap of the coding regions for structural proteins and a complex pattern of leader sequences at the 5' end of late messenger RNA. The sequence of the early region is consistent with recent proposals that the large early polypeptide of SV40 is encoded in noncontinguous segments of DNA.
Asunto(s)
Genes Virales , Virus 40 de los Simios/genética , Secuencia de Bases , Mapeo Cromosómico , Codón , Replicación del ADN , ADN Circular , ADN Viral , Genes , Transcripción Genética , Proteínas Virales/genéticaRESUMEN
We report experimental results of the orientational order parameter, the apparent tilt angle, and the field-induced tilt angle for three chiral smectic liquid crystalline materials investigated using infrared (IR) polarized spectroscopy. The common feature in these materials is use of the core 5-methyl-2- pyrimidine benzoate as the central part of the mesogen. This core is terminated by siloxane or carbosilane chains on one of the ends and by the chiral alkoxy chains on the opposite. These compounds exhibit low concomitant layer shrinkage at the smectic A^{*} (SmA^{*}) to smectic C^{*} (SmC^{*}) transition temperature and within the SmC^{*} phase itself. The maximum layer shrinkage in SmC^{*} is observed as â¼1.5%. We calculate the apparent orientational order parameter, S_{app} in the laboratory reference frame from the observed IR absorbance for homeotropic aligned samples, and the true order parameter, S, is calculated using the measured tilt angle and is also interpolated from Iso-SmA^{*} transition temperature closer to SmC^{*} phase. The apparent tilt angle in the SmA^{*} phase calculated from a comparison of order parameters S and S_{app} is found to be significantly large. A low magnitude of S_{app} found for homeotropic aligned samples in the SmA^{*} phase indicates that the order parameter plays a vital role in determining the de Vries characteristics, especially of exhibiting larger apparent tilt angles. Furthermore there is a significant increase in the true order parameter at temperatures close to SmA^{*} to SmC^{*} transition temperature in all three compounds. The planar-aligned samples are used to study the dependence of induced tilt angle on the applied electric field. The generalized Langevin-Debye model given by Shen et al. reasonably fits the experimental data on the field-induced tilt angle. The results show that the dipole moment of the tilt correlated domain in SmA^{*} diverges as temperature is lowered to the SmA^{*}-SmC^{*} transition temperature. The generalized Langevin-Debye model is also found to be extremely effective in confirming some of the conclusions of the de Vries behavior.
RESUMEN
Employing the dielectric relaxation spectroscopy technique, we have observed two different characteristics of the collective relaxation mode of an incommensurate SmC(α)(*) phase. Recent theoretical advances predict two different natures for the dielectric relaxation mode in the SmC(α)(*) phase. Our experimental results confirm two different behaviours of the relaxation mode in different temperature ranges for this phase for one unique compound having an exceptionally wide temperature range (â¼9 °C) for the SmC(α)(*) phase.
RESUMEN
Samples were collected every 2-4 weeks from a set of 37 monitoring wells over a period of 2-3 years in Araihazar, Bangladesh, to evaluate the temporal variability of groundwater composition for As and other constituents. The monitoring wells are grouped in 6 nests and span the 5-91 m depth range. Concentrations of As, Ca, Fe, K, Mg, Mn, Na, P, and S were measured by high-resolution ICPMS with a precision of 5% or better; concentrations of Cl were measured by ion chromatography. In shallow wells <30 m deep, As and P concentrations generally varied by <30%, whereas concentrations of the major ions (Na, K, Mg, Ca and Cl) and the redox-sensitive elements (Fe, Mn, and S) varied over time by up to +/-90%. In wells tapping the deeper aquifers >30 m often below clay layers concentrations of groundwater As were much lower and varied by <10%. The concentrations of major cations also varied by <10% in these deep aquifers. In contrast, the concentration of redox-sensitive constituents Fe, S, and Mn in deep aquifers varied by up to 97% over time. Thus, strong decoupling between variations in As and Fe concentrations is evident in groundwaters from shallow and deep aquifers. Comparison of the time series data with groundwater ages determined by (3)H/(3)He and (14)C dating shows that large seasonal or inter-annual variations in major cation and chloride concentrations are restricted to shallow aquifers and groundwater recharged <5 years ago. There is no corresponding change in As concentrations despite having significant variations of redox sensitive constituents in these very young waters. This is attributed to chemical buffering due to rapid equilibrium between solute and solid As. At two sites where the As content of groundwater in existing shallow wells averages 102 microg/L (range: <5 to 648 microg/L; n=118) and 272 microg/L (range: 10 to 485 microg/L; n=65), respectively, a systematic long-term decline in As concentrations lends support to the notion that flushing may slowly deplete an aquifer of As. Shallow aquifer water with >5 years (3)H/(3)He age show a constant As:P molar ratio of 9.6 over time, suggesting common mechanisms of mobilization.
Asunto(s)
Arsénico/análisis , Monitoreo del Ambiente , Agua Dulce/química , Contaminantes Químicos del Agua/análisis , Abastecimiento de Agua , Bangladesh , Agua Dulce/análisis , Abastecimiento de Agua/análisis , Abastecimiento de Agua/normasRESUMEN
OBJECTIVE: To investigate the prevalence of antibiotic resistance among Staphylococcus aureus isolated in Kuwaiti hospitals. MATERIALS AND METHODS: S. aureus were isolated and identified following standard microbiological methods. Antibacterial susceptibility test was performed by disk diffusion and the measurement of minimum inhibitory concentration with E-test strips. RESULTS: A total of 1,846 S. aureus isolates were analyzed from 13 hospitals between 1 March and 30 October 2005. They were isolated from 1,765 (95.6%) inpatients and 81 (4.4%) outpatients. Methicillin resistance was detected in 588 (32.0%) of the isolates. The methicillin-resistant S. aureus (MRSA) consisted of 461 (78%) multiresistant and 127 (22%) nonmultiresistant isolates. The nonmultiresistant MRSA consisted of epidemic MRSA-15 and community-associated MRSA. The community-associated MRSA was detected in all hospitals with MRSA, indicating its establishment in Kuwaiti hospitals. The proportion of isolates resistant to gentamicin, kanamycin, erythromycin, tetracycline, ciprofloxacin, fusidic acid and trimethoprim was higher among MRSA than methicillin-susceptible S. aureus (MSSA) isolates. Twenty-four and 22% of MRSA and MSSA isolates, respectively, expressed reduced susceptibility to vancomycin (minimum inhibitory concentration = 3-4 mg/l). CONCLUSION: The study revealed the presence of methicillin resistance in 32% of S. aureus isolated in Kuwaiti hospitals and revealed an increase in the number of MRSA and MSSA with reduced susceptibility to vancomycin.
Asunto(s)
Farmacorresistencia Bacteriana , Hospitales/estadística & datos numéricos , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/aislamiento & purificación , Antibacterianos/uso terapéutico , Humanos , Kuwait/epidemiología , Resistencia a la Meticilina , Pruebas de Sensibilidad Microbiana , Vigilancia de la Población , Prevalencia , Infecciones Estafilocócicas/tratamiento farmacológico , Teicoplanina/uso terapéutico , Resistencia a la VancomicinaRESUMEN
We identified the Schizosaccharomyces pombe mex67 gene (spmex67) as a multicopy suppressor of rae1-167 nup184-1 synthetic lethality and the rae1-167 ts mutation. spMex67p, a 596-amino-acid-long protein, has considerable sequence similarity to the Saccharomyces cerevisiae Mex67p (scMex67p) and human Tap. In contrast to scMEX67, spmex67 is essential for neither growth nor nuclear export of mRNA. However, an spmex67 null mutation (Deltamex67) is synthetically lethal with the rae1-167 mutation and accumulates poly(A)(+) RNA in the nucleus. We identified a central region (149 to 505 amino acids) within spMex67p that associates with a complex containing Rae1p that complements growth and mRNA export defects of the rae1-167 Deltamex67 synthetic lethality. This region is devoid of RNA-binding, N-terminal nuclear localization, and the C-terminal nuclear pore complex-targeting regions. The (149-505)-green fluorescent protein (GFP) fusion is found diffused throughout the cell. Overexpression of spMex67p inhibits growth and mRNA export and results in the redistribution of the diffused localization of the (149-505)-GFP fusion to the nucleus and the nuclear periphery. These results suggest that spMex67p competes for essential mRNA export factor(s). Finally, we propose that the 149-505 region of spMex67p could act as an accessory factor in Rae1p-dependent transport and that spMex67p participates at various common steps with Rae1p export complexes in promoting the export of mRNA.
Asunto(s)
Transporte Activo de Núcleo Celular , Proteínas Fúngicas/metabolismo , Proteínas Asociadas a Matriz Nuclear , Proteínas Nucleares/metabolismo , Proteínas de Transporte Nucleocitoplasmático , ARN Mensajero/metabolismo , Proteínas de Unión al ARN/metabolismo , Proteínas de Saccharomyces cerevisiae , Proteínas de Schizosaccharomyces pombe , Secuencia de Aminoácidos , Sitios de Unión , Compartimento Celular , Secuencia Conservada , Proteínas Fúngicas/genética , Prueba de Complementación Genética , Datos de Secuencia Molecular , Mutación , Poro Nuclear/metabolismo , Proteínas de Complejo Poro Nuclear , Fenotipo , Unión Proteica , ARN de Hongos/metabolismo , Schizosaccharomyces , Homología de Secuencia de Aminoácido , Supresión GenéticaRESUMEN
To identify components of the mRNA export machinery in Schizosaccharomyces pombe, a screen was developed to identify mutations that were synthetically lethal with the conditional mRNA export allele rae1-167. Mutations defining three complementation groups were isolated, and here we report the characterization of npp106 (for nuclear pore protein of 106 kDa). This gene encodes a predicted protein that has significant similarity to the Nic96p nucleoporin of Saccharomyces cerevisiae. Consistent with Npp106p being a nucleoporin, a functional green fluorescent protein (GFP)-tagged Npp106p localized to the nuclear periphery. In contrast to NIC96, the npp106 gene is not essential. Moreover, a delta npp106 mutant did not show cytoplasmic mislocalization of a simian virus 40 nuclear localization signal-GFP-LacZ reporter protein, and a fraction of cells had accumulation of poly(A)+ RNA in the nucleus. A consequence of the synthetic lethality between rae1-167 and npp106-1 was the accumulation of poly(A)+ RNA in the nucleus when cells were grown under synthetic lethal conditions. In addition to npp106-1, which is a nonsense mutation that truncates the protein at amino acid 292, the delta npp106 mutation was synthetically lethal with rae1-167, suggesting that the synthetic lethality is a consequence of the loss of a function of npp106. We further demonstrate that a region between amino acids 74 and 348 of Npp106p is required for complementation of the synthetic lethality. These results uncover a potential direct or indirect involvement of Npp106p in mRNA export.
Asunto(s)
Proteínas Fúngicas/metabolismo , Proteínas de la Membrana , Proteínas Asociadas a Matriz Nuclear , Proteínas Nucleares/metabolismo , Proteínas de Transporte Nucleocitoplasmático , ARN de Hongos/metabolismo , ARN Mensajero/metabolismo , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/metabolismo , Proteínas de Schizosaccharomyces pombe , Schizosaccharomyces/metabolismo , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Transporte Biológico Activo , Clonación Molecular , Cartilla de ADN/genética , Proteínas Fúngicas/genética , Genes Fúngicos , Genes Letales , Prueba de Complementación Genética , Humanos , Microscopía Electrónica , Datos de Secuencia Molecular , Mutación , Membrana Nuclear/metabolismo , Proteínas de Complejo Poro Nuclear , Proteínas Nucleares/genética , Reacción en Cadena de la Polimerasa , Saccharomyces cerevisiae/genética , Schizosaccharomyces/genética , Schizosaccharomyces/ultraestructura , Homología de Secuencia de Aminoácido , Especificidad de la EspecieRESUMEN
We present the nucleotide sequence of the coding region of the rat c-rasH-1 gene and a partial sequence analysis of the rat c-rasH-2 gene. By comparing these sequences with the Harvey murine sarcoma virus ras gene, we predict that the p21 protein encoded by the Harvey virus differs from the cellular c-rasH-1-encoded p21 at only two amino acids; those at positions 12 and 59. Alterations at each of these positions may play a role in activating the viral p21 protein. The c-rasH-2 gene is likely to be a nonfunctional pseudogene because it lacks introns, cannot be activated to transform NIH 3T3 cells, and differs in sequence from both c-rasH-1 and v-rasH at several base pair positions.