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1.
BMC Pregnancy Childbirth ; 19(1): 85, 2019 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-30832681

RESUMEN

BACKGROUND: Double-layer compared to single-layer closure of the uterus after a caesarean section (CS) leads to a thicker myometrial layer at the site of the CS scar, also called residual myometrium thickness (RMT). It possibly decreases the development of a niche, which is an interruption of the myometrium at the site of the uterine scar. Thin RMT and a niche are associated with gynaecological symptoms, obstetric complications in a subsequent pregnancy and delivery and possibly with subfertility. METHODS: Women undergoing a first CS regardless of the gestational age will be asked to participate in this multicentre, double blinded randomised controlled trial (RCT). They will be randomised to single-layer closure or double-layer closure of the uterine incision. Single-layer closure (control group) is performed with a continuous running, unlocked suture, with or without endometrial saving technique. Double-layer closure (intervention group) is performed with the first layer in a continuous unlocked suture including the endometrial layer and the second layer is also continuous unlocked and imbricates the first. The primary outcome is the reported number of days with postmenstrual spotting during one menstrual cycle nine months after CS. Secondary outcomes include surgical data, ultrasound evaluation at three months, menstrual pattern, dysmenorrhea, quality of life, and sexual function at nine months. Structured transvaginal ultrasound (TVUS) evaluation is performed to assess the uterine scar and if necessary saline infusion sonohysterography (SIS) or gel instillation sonohysterography (GIS) will be added to the examination. Women and ultrasound examiners will be blinded for allocation. Reproductive outcomes at three years follow-up including fertility, mode of delivery and complications in subsequent deliveries will be studied as well. Analyses will be performed by intention to treat. 2290 women have to be randomised to show a reduction of 15% in the mean number of spotting days. Additionally, a cost-effectiveness analysis will be performed from a societal perspective. DISCUSSION: This RCT will provide insight in the outcomes of single- compared to double-layer closure technique after CS, including postmenstrual spotting and subfertility in relation to niche development measured by ultrasound. TRIAL REGISTRATION: Dutch Trial Register ( NTR5480 ). Registered 29 October 2015.


Asunto(s)
Cesárea/métodos , Metrorragia/etiología , Técnicas de Sutura/efectos adversos , Útero/cirugía , Cicatriz/diagnóstico por imagen , Cicatriz/etiología , Método Doble Ciego , Dismenorrea/etiología , Endosonografía , Femenino , Fertilidad , Humanos , Menstruación , Complicaciones del Trabajo de Parto/etiología , Embarazo , Calidad de Vida , Ensayos Clínicos Controlados Aleatorios como Asunto , Sexualidad , Útero/diagnóstico por imagen
2.
Microbiol Mol Biol Rev ; 65(2): 261-87 ; second page, table of contents, 2001 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-11381102

RESUMEN

Continuous research spanning more than three decades has made the Bacillus bacteriophage phi29 a paradigm for several molecular mechanisms of general biological processes, such as DNA replication, regulation of transcription, phage morphogenesis, and phage DNA packaging. The genome of bacteriophage phi29 consists of a linear double-stranded DNA (dsDNA), which has a terminal protein (TP) covalently linked to its 5' ends. Initiation of DNA replication, carried out by a protein-primed mechanism, has been studied in detail and is considered to be a model system for the protein-primed DNA replication that is also used by most other linear genomes with a TP linked to their DNA ends, such as other phages, linear plasmids, and adenoviruses. In addition to a continuing progress in unraveling the initiation of DNA replication mechanism and the role of various proteins involved in this process, major advances have been made during the last few years, especially in our understanding of transcription regulation, the head-tail connector protein, and DNA packaging. Recent progress in all these topics is reviewed. In addition to phi29, the genomes of several other Bacillus phages consist of a linear dsDNA with a TP molecule attached to their 5' ends. These phi29-like phages can be divided into three groups. The first group includes, in addition to phi29, phages PZA, phi15, and BS32. The second group comprises B103, Nf, and M2Y, and the third group contains GA-1 as its sole member. Whereas the DNA sequences of the complete genomes of phi29 (group I) and B103 (group II) are known, only parts of the genome of GA-1 (group III) were sequenced. We have determined the complete DNA sequence of the GA-1 genome, which allowed analysis of differences and homologies between the three groups of phi29-like phages, which is included in this review.


Asunto(s)
Fagos de Bacillus/genética , Bacillus/virología , Secuencia de Aminoácidos , Bacillus/metabolismo , Fagos de Bacillus/química , Fagos de Bacillus/crecimiento & desarrollo , Secuencia de Bases , Replicación del ADN , ADN Viral/metabolismo , Datos de Secuencia Molecular , ARN Viral/metabolismo , Transcripción Genética , Proteínas Virales/química , Proteínas Virales/genética
3.
Vaccine ; 35(11): 1517-1523, 2017 03 13.
Artículo en Inglés | MEDLINE | ID: mdl-28196736

RESUMEN

OBJECTIVE: To explore the nature and severity of side effects and future preference of intradermal versus intramuscular influenza vaccination in healthcare workers. DESIGN: Prospective cohort study. SETTING: Two University Medical Centers in The Netherlands. PARTICIPANTS: Healthcare workers receiving an influenza vaccination. METHODS: Healthcare workers that were vaccinated during the influenza vaccination season of 2012-2013 were approached for participation in a questionnaire study. The questionnaire was divided into two parts. The first part had to be answered directly after vaccination and the second part two weeks after vaccination. The motivation for vaccine uptake, whether or not the HCWs had direct contact with patients and the prevalence and severity of local and systemic side effects of influenza vaccination were explored. In addition, it was assessed how participants experienced the vaccination and which type of administration they preferred for future vaccination. RESULTS: Side effects of vaccination were more prevalent in the intradermal group versus the intramuscular group (56% versus 26%, p<0.001). Local side effects were perceived as more severe in healthcare workers receiving the intradermal vaccine. Directly after vaccination, healthcare workers preferred the intradermal vaccination. Two weeks after vaccination both types of vaccine were equally appreciated. CONCLUSIONS: This study shows that there are significant differences in the nature and severity of side effects upon intramuscular and intradermal influenza vaccination. This difference did not result in a preference among the vaccinated subjects for one type of vaccine.


Asunto(s)
Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/epidemiología , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/patología , Personal de Salud , Vacunas contra la Influenza/administración & dosificación , Gripe Humana/prevención & control , Vacunación/efectos adversos , Centros Médicos Académicos , Administración Intranasal , Adulto , Anciano , Femenino , Humanos , Inyecciones Intramusculares , Masculino , Persona de Mediana Edad , Países Bajos , Estudios Prospectivos , Encuestas y Cuestionarios , Vacunación/estadística & datos numéricos , Adulto Joven
4.
FEMS Microbiol Rev ; 21(4): 337-68, 1998 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-9532747

RESUMEN

Most small plasmids of Gram-positive bacteria use the rolling-circle mechanism of replication and several of these have been studied in considerable detail at the DNA level and for the function of their genes. Although most of the common laboratory Bacillus subtilis 168 strains do not contain plasmids, several industrial strains and natural soil isolates do contain rolling-circle replicating (RCR) plasmids. So far, knowledge about these plasmids was mainly limited to: (i) a classification into seven groups, based on size and restriction patterns; and (ii) DNA sequences of the replication region of a limited number of them. To increase the knowledge, also with respect to other functions specified by these plasmids, we have determined the complete DNA sequence of four plasmids, representing different groups, and performed computer-assisted and experimental analyses on the possible function of their genes. The plasmids analyzed are pTA1015 (5.8 kbp), pTA1040 (7.8 kbp), pTA1050 (8.4 kbp), and pTA1060 (8.7 kbp). These plasmids have a structural organization similar to most other known RCR plasmids. They contain highly related replication functions, both for leading and lagging strand synthesis. pTA1015 and pTA1060 contain a mobilization gene enabling their conjugative transfer. Strikingly, in addition to the conserved replication modules, these plasmids contain unique module(s) with genes which are not present on known RCR plasmids of other Gram-positive bacteria. Examples are genes encoding a type I signal peptidase and genes encoding proteins belonging to the family of response regulator aspartate phosphatases. The latter are likely to be involved in the regulation of post-exponential phase processes. The presence of these modules on plasmids may reflect an adaptation to the special conditions to which the host cells were exposed.


Asunto(s)
Bacillus subtilis/genética , Replicación del ADN , Bacterias Grampositivas/genética , Plásmidos/genética , Genes Bacterianos/genética , Datos de Secuencia Molecular , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Homología de Secuencia de Ácido Nucleico
5.
Vision Res ; 45(12): 1587-602, 2005 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-15781075

RESUMEN

When components of a shape are presented asynchronously during smooth pursuit, the retinal image determines the perceived shape, as if the parts belong to the moving object that the eyes are pursuing. Saccades normally shift our gaze between structures of interest, so there is no reason to expect anything to have moved with the eyes. We therefore decided to examine how people judge the separation between a target flashed before and another flashed after a saccade. Subjects tracked a jumping dot with their eyes. Targets were flashed at predetermined retinal positions, with a 67-242 ms interval between the flashes. After each trial subjects indicated where they had seen the targets. We selected the trials on which subjects made a complete saccade between the presentations of the two targets. For short inter-target intervals, subjects' judgements depended almost exclusively on the retinal separation, even when there were conspicuous visual references nearby. Even for the longest intervals, only part of the change in eye orientation was taken into consideration. These findings cannot simply be accounted for on the basis of the mislocalisation of individual targets or a compression of space near saccades. We conclude that the retinal separation determines the perceived separation between targets presented with a short interval between them, irrespective of any intervening eye movements.


Asunto(s)
Movimientos Sacádicos/fisiología , Percepción Visual/fisiología , Discriminación en Psicología/fisiología , Humanos , Juicio/fisiología , Percepción de Movimiento/fisiología , Orientación/fisiología , Reconocimiento Visual de Modelos/fisiología , Estimulación Luminosa/métodos , Seguimiento Ocular Uniforme/fisiología , Tiempo de Reacción , Percepción Espacial/fisiología
6.
Eur J Obstet Gynecol Reprod Biol ; 47(1): 59-65, 1992 Oct 23.
Artículo en Inglés | MEDLINE | ID: mdl-1426512

RESUMEN

The risks and benefits of prophylactic bilateral oophorectomy (BO) accompanying hysterectomy are reviewed. The potential reduction in the risk of subsequent ovarian cancer is quantified using literature data and a mathematical model. The risks of subsequent breast cancer from low-dose ERT are estimated using a comprehensive mathematical model. It is hypothesized that BO may have a substantial protective effect on breast cancer risk despite subsequent low-dose or non-low-dose ERT, when BO is performed at an early age. In women with a family history of ovarian cancer or breast cancer, the individual risks must be assessed on the basis of a pedigree analysis. In conclusion, a decision on BO must be based on weighing the potential benefits of reduced ovarian and breast cancer risks against the psychological importance of retaining the ovaries and the risk of osteoporosis and cardiovascular disease when compliance with ERT is less than perfect. The provided quantitative data may help in making the right decision.


Asunto(s)
Neoplasias Ováricas/epidemiología , Neoplasias Ováricas/prevención & control , Ovariectomía , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias de la Mama/epidemiología , Neoplasias de la Mama/etiología , Técnicas de Apoyo para la Decisión , Terapia de Reemplazo de Estrógeno , Femenino , Humanos , Histerectomía , Incidencia , Tablas de Vida , Persona de Mediana Edad , Modelos Estadísticos , Osteoporosis Posmenopáusica/epidemiología , Osteoporosis Posmenopáusica/etiología , Osteoporosis Posmenopáusica/prevención & control , Ovariectomía/efectos adversos , Ovariectomía/psicología , Factores de Riesgo
7.
Midwifery ; 12(1): 4-10, 1996 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-8715930

RESUMEN

OBJECTIVE: The aim of this study was to determine the feasibility of co-operation within maternity and obstetric care between midwives, general practitioners (GPs) and obstetricians. DESIGN: descriptive correlational study. SETTING: The Netherlands. Policy is towards more co-operation between primary and secondary health care. However, in Dutch health care midwives, GPs and obstetricians may also have conflicts of interests. PARTICIPANTS: members of obstetric co-operation groups (91 midwives, 53 GPs, 31 obstetricians) completed a questionnaire. MEASUREMENTS AND FINDINGS: in the questionnaire information was collected on what members of obstetric co-operative groups expect from co-operation. Findings indicated that consensus existed about experienced advantages and disadvantages of co-operation, tasks that should be achieved, and how obstetric co-operative groups could be set up. Nevertheless, there was evidence of competition and there were also conflicting ideas about co-operation. KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE: it is concluded that the findings have implications for the organisation of an obstetric co-operative group. If professionals want to start such a group it is preferable to start with topics that benefit all participants (win-win situation) and motivate them to participate actively. A second step may be an attempt to reach agreement about how to communicate with each other in the case of referrals and consultations. During this phase mutual trust and respect may grow, so that finally more difficult problems can be discussed (mixed-motives situation).


Asunto(s)
Conducta Competitiva , Conducta Cooperativa , Medicina Familiar y Comunitaria/organización & administración , Relaciones Interprofesionales , Enfermeras Obstetrices/organización & administración , Obstetricia/organización & administración , Actitud del Personal de Salud , Conflicto Psicológico , Estudios de Factibilidad , Femenino , Humanos , Masculino , Países Bajos , Enfermeras Obstetrices/psicología , Grupo de Atención al Paciente/organización & administración , Encuestas y Cuestionarios
8.
Tijdschr Kindergeneeskd ; 53(3): 92-8, 1985 Jun.
Artículo en Holandés | MEDLINE | ID: mdl-4035661

RESUMEN

In the Netherlands nation-wide screening for CH began in January 1981. The aim of the combined T4-TSH screening method is to detect all forms of CH, primary as well as secondary and tertiary. More than 99% of the newborns are screened. The rate of false-positives in premature infants was reduced in June 1982 by a change of the indications for follow-up. Further study is performed on T4 values of premature infants. The information, given to the parents in case of recall, is not optimal yet. Although there is still delay in screening and follow-up, the initiation of treatment is considerably advanced. The effect of earlier treatment on development will be assessed by Prof. Dr. A. F. Kalverboer. Very likely, the early treatment will lead to a considerable reduction of damage to the central nervous system.


Asunto(s)
Hipotiroidismo Congénito , Enfermedades del Prematuro/sangre , Tiroxina/sangre , Desarrollo Infantil , Reacciones Falso Positivas , Humanos , Hipotiroidismo/sangre , Hipotiroidismo/psicología , Recién Nacido , Padres/educación
10.
IEEE Trans Biomed Eng ; 28(4): 354-7, 1981 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-7287035
13.
Int J Qual Health Care ; 9(1): 23-33, 1997 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-9154488

RESUMEN

BACKGROUND: The system and delivery of health care tend to suffer from fragmentation, resulting in discontinuous and costly care. Local cooperation between caregivers is essential to achieve appropriate, timely, continuous and efficient care. The article develops a general comprehensive patient-centered model of quality of care related to local cooperation between caregivers. The model can be used in quality improvement and research. THE PROPOSED MODEL: Within the framework of Donabedian's triad (structure-->process-->outcome), cooperation between caregivers is divided into two parts. Firstly, client related cooperation (multiple caregivers to one patient) is a part of the process of health care and relevant for important quality aspects: appropriateness, timeliness, continuity of care, effectiveness and efficiency. Secondly, local cooperation between caregivers, which is not restricted to one patient, is called non client related cooperation. Such non client related cooperation creates conditions for optimal patient care. Non client related cooperation has different degrees, dependent on the existence of agreements between the caregivers (such as protocols) and evaluation of these agreements. The highest degree of non client related cooperation is continuous quality improvement. To achieve a certain degree of non client related cooperation, conditions must be fulfilled in several fields (organization, information, financing and participants). APPLICATION OF THE MODEL: A "how to use the model in eight steps" is given and possible operationalizations of key concepts in the model are outlined. Finally, the use of the model is illustrated by two examples.


Asunto(s)
Atención Integral de Salud/normas , Modelos Organizacionales , Grupo de Atención al Paciente/organización & administración , Atención Dirigida al Paciente/organización & administración , Calidad de la Atención de Salud/organización & administración , Cuidadores/organización & administración , Continuidad de la Atención al Paciente , Conducta Cooperativa , Eficiencia Organizacional , Humanos , Relaciones Interprofesionales , Evaluación de Procesos y Resultados en Atención de Salud , Atención Dirigida al Paciente/normas
14.
Nucleic Acids Res ; 23(4): 612-9, 1995 Feb 25.
Artículo en Inglés | MEDLINE | ID: mdl-7899081

RESUMEN

In this paper we describe the isolation and characterization of single strand origins (SSOs) of several cryptic Bacillus subtilis plasmids which use the rolling-circle mechanism of replication. The plasmids used in this study involved pTA1015, pTA1020, pTA1030, pTA1040, pTA1050 and pTA1060. The SSO of pTA1015 was isolated by shotgun cloning in a specially designed vector, pWM100, which has no SSO of its own. Sequence analysis revealed that the SSO of pTA1015 is almost identical to formerly described palT type SSOs. Also pTA1020 and pTA1060 were shown to contain SSOs highly homologous to palT. Using Southern hybridization with the palT of pTA1015 as a probe, the SSO of pTA1040 was cloned. Sequence analysis revealed a region of 200 bp which is 77% identical to the palT of pTA1015. The plasmids pTA1030 and pTA1050 contain an SSO which is highly homologous to the SSO of pTA1040. The majority of the SSOs of rolling-circle plasmids from B.subtilis seem to belong to two related families which we denote as palT1 (present on pTA1015, pTA1020 and pTA1060) and palT2 (present on pTA1030, pTA1040 and pTA1050). Both families of SSOs are highly efficient single-strand-conversion signals in B.subtilis.


Asunto(s)
Bacillus subtilis/genética , Replicación del ADN , ADN Bacteriano/genética , ADN Circular/genética , Plásmidos/genética , Origen de Réplica , Secuencia de Bases , Clonación Molecular , ADN de Cadena Simple/genética , Escherichia coli/genética , Vectores Genéticos/genética , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Selección Genética , Alineación de Secuencia , Homología de Secuencia de Ácido Nucleico
15.
Mol Microbiol ; 39(3): 731-46, 2001 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-11169113

RESUMEN

An early expressed operon, located at the right end of the linear bacteriophage phi29 genome, contains open reading frame (ORF)16.7, whose deduced protein sequence of 130 amino acids is conserved in phi29-related phages. Here, we show that this ORF actually encodes a protein, p16.7, which is abundantly and early expressed after infection. p16.7 is a membrane protein, and the N-terminally located transmembrane-spanning domain is required for its membrane localization. The variant p16.7A, in which the N-terminal membrane anchor was replaced by a histidine-tag, was purified and characterized. Purified p16.7A was shown to form dimers in solution. To study the in vivo role of p16.7, a phi29 mutant containing a suppressible mutation in gene 16.7 was constructed. In vivo phage DNA replication was affected in the absence of p16.7, especially at early infection times. Based on the results, the putative role of p16.7 in in vivo phi29 DNA replication is discussed.


Asunto(s)
Fagos de Bacillus/genética , Fagos de Bacillus/metabolismo , Replicación del ADN , Proteínas de la Membrana/metabolismo , Proteínas Virales/metabolismo , Secuencia de Aminoácidos , Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Bacillus subtilis/virología , Western Blotting , ADN Viral/metabolismo , Proteínas Fluorescentes Verdes , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Datos de Secuencia Molecular , Mutación , Plásmidos , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Análisis de Secuencia de ADN , Transcripción Genética , Transformación Bacteriana , Proteínas Virales/química , Proteínas Virales/genética
16.
Mol Microbiol ; 29(3): 787-98, 1998 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-9723918

RESUMEN

The accumulation of subgenomic phage phi29 DNA molecules with specific sizes was observed after prolonged infection times with delayed lysis phage mutants. Whereas the majority of the molecules had a size of 4 kb, additional DNA species were observed with sizes of 8.2, 6.5, 2.3, 2 and 1 kb. Most of the molecules were shown to originate from the right end of the linear Bacillus subtilis phage phi29 genome. The nature of the 4, 2.3, 2 and 1 kb molecules was studied. The 2 kb molecules were shown to be single-stranded self-complementary strands forming hairpin structures. The other molecules consisted of palindromic linear double-stranded DNA molecules. Most probably, the subgenomic DNA molecules were formed when the moving phage replication fork from the right origin encountered a block that induces the DNA polymerase to switch template. Once formed, the subgenomic molecules are then amplified in vivo. Determination of the centres of symmetry of the 4 and 1 kb molecules revealed that both contained the almost 16 bp perfect dyad symmetry element (DSE): 5'-TGTTtCAC-GTGg-AACA-3' being a likely candidate for a protein binding site. Database analysis showed that this sequence occurs four times in the phi29 genome. In addition, the almost identical sequence 5'-TgGTTTCAC-GTGGAAtCA-3' was found once. These five DSEs are all located in the right half of the phi29 genome, and the same sequences are also present in the linear DNA of related B. subtilis phages. Most interestingly, this sequence is also found in the spoOJ gene of the B. subtilis chromosome. Recently, it has been shown that the SpoOJ protein is associated in vivo with the same DSE. As the same subgenomic phi29 DNA molecules accumulate after infection of B. subtilis spoOJ deletion strains, it is likely that, in addition to and/or independently of SpoOJ, other protein(s) bind to DSE.


Asunto(s)
Fagos de Bacillus/genética , ADN Viral , ADN Polimerasa Dirigida por ADN/metabolismo , Genoma Viral , Bacillus subtilis/genética , Sitios de Unión , ADN de Cadena Simple , Eliminación de Gen , Expresión Génica , Genes Virales , Prueba de Complementación Genética , Conformación de Ácido Nucleico , Moldes Genéticos
17.
Plasmid ; 33(2): 79-89, 1995 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-7597110

RESUMEN

The effects of the single-strand origins (SSOs) of plasmid pMV158 on (i) the conversion of its single-stranded (ss) replication intermediates to double-stranded (ds) plasmid DNA and (ii) its maintenance were analyzed. The rolling-circle plasmid pMV158, which replicates via ssDNA intermediates, contains two single-strand origins (SSOs) of replication, palA and palU. In this paper the results obtained with Bacillus subtilis are described; complementary studies with Lactococcus lactis are presented in the accompanying paper (Meijer et al., 1995). While in L. lactis both SSOs are functional as ssDNA conversion signal, only palU appeared to be active B. subtilis. Similar to the situation in L. lactis, the accumulation of large amounts of ssDNA resulted in a severe decrease in plasmid maintenance in B. subtilis. In the latter bacterium large amounts of ssDNA were only accumulated, however, when plasmids lacking a functional SSO were propagated in RecA mutant strains. In wild-type RecA strains these plasmids accumulated only modest amounts of ssDNA and they were maintained at fairly stable levels. The results suggest that in B. subtilis a RecA-mediated alternative pathway exists for the conversion of ssDNA which can improve plasmid maintenance. In addition to ssDNA accumulation and the antagonizing role of RecA therein, two other plasmid regions were shown to affect pMV158 maintenance in B. subtilis. One was the mob gene region, which had a negative effect on plasmid maintenance, and the other the palA type SSO. Although palA was not functional as an ssDNA conversion signal in B. subtilis, its presence had a positive effect on pMV158 maintenance.


Asunto(s)
Bacillus subtilis/genética , Replicación del ADN , ADN Bacteriano/biosíntesis , ADN de Cadena Simple/biosíntesis , Plásmidos/genética , Proteínas Bacterianas/fisiología , ADN/biosíntesis , ADN Bacteriano/genética , Origen de Réplica
18.
Plasmid ; 33(2): 91-9, 1995 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-7597111

RESUMEN

The effects of the single-strand origins (SSOs) of the broad-host-range streptococcal plasmid pMV158 on (i) the conversion of its single-stranded (ss) DNA replication intermediates to double-stranded (ds) plasmid DNA and (ii) its maintenance were analyzed. pMV158 is distinguished from most other plasmids that replicate by the rolling-circle mechanism by the presence of two single-strand origins of replication, palA and palU. In this paper the results obtained with Lactococcus lactis are presented; complementary studies with Bacillus subtilis are presented in the accompanying paper (Meijer et al., 1995). In the presence of both SSOs, no ss plasmid DNA was observed in L. lactis. The removal of either palA or palU resulted in the appearance of low amounts of ssDNA. High amounts of ssDNA were detected, however, when both SSOs were deleted. The results indicated that both SSOs were active, albeit that palU was the most effective of the two. In the presence of both SSOs, the plasmid was stably maintained in L. lactis under nonselective growth conditions. Also, the derivatives containing only one of the two SSOs were maintained rather stably. In contrast, the derivative devoid of both SSOs was poorly maintained. It was concluded that, in the absence of a functional SSO, the generation of large amounts of ssDNA drastically reduces the maintenance of pMV158 in L. lactis. The results also showed that the presence of the plasmid-located mob gene, required for conjugative mobilization, was involved neither in the accumulation of ssDNA nor in the maintenance of pMV158.


Asunto(s)
Replicación del ADN , ADN Bacteriano/biosíntesis , ADN de Cadena Simple/biosíntesis , Lactococcus lactis/genética , Plásmidos/genética , Proteínas Bacterianas/fisiología , ADN/biosíntesis , ADN Bacteriano/genética , Modelos Genéticos , Origen de Réplica
19.
Nucleic Acids Res ; 23(16): 3214-23, 1995 Aug 25.
Artículo en Inglés | MEDLINE | ID: mdl-7667098

RESUMEN

A 3.1 kb fragment of the large (approximately 55 kb) Bacillus subtilis plasmid pLS20 containing all the information for autonomous replication was cloned and sequenced. In contrast to the parental plasmid, derived minireplicons were unstably maintained. Using deletion analysis the fragment essential and sufficient for replication was delineated to 1.1 kb. This 1.1 kb fragment is located between two divergently transcribed genes, denoted orfA and orfB, neither of which is required for replication. orfA shows homology to the B.subtilis chromosomal genes rapA (spoOL, gsiA) and rapB (spoOP). The 1.1 kb fragment, which is characterized by the presence of several regions of dyad symmetry, contains no open reading frames of more than 85 codons and shows no similarity with other known plasmid replicons. The structural organization of the pLS20 minimal replicon is entirely different from that of typical rolling circle plasmids from Gram-positive bacteria. The pLS20 minireplicons replicate in polA5 and recA4 B.subtilis strains. Taken together, these results strongly suggest that pLS20 belongs to a new class of theta replicons.


Asunto(s)
Bacillus subtilis/genética , Replicación del ADN/genética , Plásmidos/genética , Replicón , Secuencia de Aminoácidos , Bacillus subtilis/metabolismo , Proteínas Bacterianas/genética , Secuencia de Bases , Clonación Molecular , Cartilla de ADN/genética , Genes Bacterianos , Datos de Secuencia Molecular , Plásmidos/biosíntesis
20.
J Biol Chem ; 274(21): 15073-9, 1999 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-10329712

RESUMEN

Initiation of phage phi29 DNA replication starts with the recognition of the origin of replication, located at both ends of the linear DNA, by a heterodimer formed by the phi29 terminal protein (TP) and the phi29 DNA polymerase. The parental TP, covalently linked to the DNA ends, is one of the main components of the replication origin. Here we provide evidence that recognition of the origin is mediated through interactions between the TP of the TP/DNA polymerase heterodimer, called primer TP, and the parental TP. Based on amino acid sequence comparisons, various phi29 TP mutants were generated at conserved amino acid residues from positions 61 to 87. In vitro phi29 DNA amplification analysis revealed that residues Asn80 and Tyr82 are essential for functional interaction between primer and parental TP required for recognition of the origin of replication. Although these mutant TPs can form functional heterodimers with phi29 DNA polymerase that are able to recognize the origin of replication, these heterodimers are not able to recognize an origin containing a mutant TP.


Asunto(s)
Asparagina/metabolismo , Origen de Réplica , Tirosina/metabolismo , Proteínas Virales/metabolismo , Secuencia de Aminoácidos , Datos de Secuencia Molecular
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