RESUMEN
BACKGROUND: Although widely acknowledged that adequate maternal nutrition is important for mother and baby, limited research has focussed on women with severe mental illnesses (SMI) in pregnancy. The present study reports on nutritional factors and food choices and investigates barriers and facilitators to healthy nutritional choices by pregnant women with SMI. METHODS: A prospective mixed method study was undertaken of 38 pregnant women with SMI, including a cross-sectional survey, a food frequency questionnaire and 12 postnatal qualitative interviews, with integrated analysis of all data. RESULTS: Elevated rates of obesity (35%) were found, with 82% of women having above the recommended gestational weight gain. Despite perceived knowledge, 32% of women did not meet any of the Five Food Group serving recommendations for pregnancy and consumed above-recommended levels for processed (19%) and sugar snacks (51%). Thematic analysis identified four main barriers: a discrepancy between knowledge and action, food cravings, mental health, and physical health. During pregnancy, food cravings were reported in 66% of women, psychological distress in 71% and physical distress in 37%. Screening identified 19% with potential eating disordered behaviours. Despite the challenges, several facilitators were identified and covered three themes: access to a dietitian, information delivery and support, and comprehensive care. DISCUSSION: Women with SMI in pregnancy struggle with issues of obesity, gestational weight gain, food cravings and possible eating disorder behaviours. They have additional challenges when pregnant, with management of their mental health and physical health having a direct impact. Interventional strategies in this population should incorporate findings from this research.
Asunto(s)
Dieta Saludable/psicología , Trastornos Mentales/psicología , Complicaciones del Embarazo/psicología , Mujeres Embarazadas/psicología , Adulto , Ansia , Estudios Transversales , Encuestas sobre Dietas , Trastornos de Alimentación y de la Ingestión de Alimentos/psicología , Femenino , Preferencias Alimentarias/psicología , Ganancia de Peso Gestacional , Humanos , Fenómenos Fisiologicos Nutricionales Maternos , Trastornos Mentales/fisiopatología , Estado Nutricional , Obesidad/psicología , Embarazo , Complicaciones del Embarazo/fisiopatología , Estudios Prospectivos , Investigación CualitativaRESUMEN
Using high-resolution melting (HRM) analysis, we developed a cost-effective method to genotype a set of 13 phylogenetically informative single-nucleotide polymorphisms (SNPs) within the genome of Bacillus anthracis. SNP discrimination assays were performed in monoplex or duplex and applied to 100 B. anthracis isolates collected in France from 1953 to 2009 and a few reference strains. HRM provided a reliable and cheap alternative to subtype B. anthracis into one of the 12 major sublineages or subgroups. All strains could be correctly positioned on the canonical SNP (canSNP) phylogenetic tree, except the divergent Pasteur vaccine strain ATCC 4229. We detected the cooccurrence of three canSNP subgroups in France. The dominant B.Br.CNEVA sublineage was found to be prevalent in the Alps, the Pyrenees, the Auvergne region, and the Saône-et-Loire department. Strains affiliated with the A.Br.008/009 subgroup were observed throughout most of the country. The minor A.Br.001/002 subgroup was restricted to northeastern France. Multiple-locus variable-number tandem-repeat analysis using 24 markers further resolved French strains into 60 unique profiles and identified some regional patterns. Diversity found within the A.Br.008/009 and B.Br.CNEVA subgroups suggests that these represent old, ecologically established clades in France. Phylogenetic relationships with strains from other parts of the world are discussed.
Asunto(s)
Carbunco/microbiología , Carbunco/veterinaria , Bacillus anthracis/clasificación , Bacillus anthracis/genética , Microbiología Ambiental , Variación Genética , Tipificación Molecular/métodos , Animales , Bacillus anthracis/aislamiento & purificación , Análisis por Conglomerados , ADN Bacteriano/química , ADN Bacteriano/genética , Francia , Humanos , Repeticiones de Minisatélite , Datos de Secuencia Molecular , Tipificación Molecular/economía , Filogeografía , Polimorfismo de Nucleótido Simple , Análisis de Secuencia de ADN , Temperatura de TransiciónRESUMEN
The purpose of the survey was the routine assessment of the MTBDRplus(®) kit performance in the determination and characterization of Mycobacterium tuberculosis resistance to rifampicin. The survey was carried out on a collection of 144 strains (126 of which were resistant to rifampicin) isolated on patients from 15 countries. Sensitivity to antituberculosis drugs was determined by a liquid culture system and the reference method was the amplification and sequencing of a target region of the rpoB gene whose mutations are responsible for rifampicin resistance (codons 507 to 533). The assessed kit was based on a reverse hybridization technique using eight overlapping probes covering the target region and four probes representing the most-frequently observed mutations. The assay performance was found excellent, specificity: 100%, sensitivity: 99.2%; 17 mutations affecting 10 codons were reported, two of which were newly identified.
Asunto(s)
Antituberculosos/farmacología , Mycobacterium tuberculosis/efectos de los fármacos , Reacción en Cadena de la Polimerasa/métodos , Juego de Reactivos para Diagnóstico , Rifampin/farmacología , Tuberculosis/microbiología , Proteínas Bacterianas/genética , Codón/genética , ADN Bacteriano/genética , ARN Polimerasas Dirigidas por ADN , Recolección de Datos , Djibouti/epidemiología , Farmacorresistencia Microbiana/genética , Farmacorresistencia Bacteriana Múltiple/genética , Francia/epidemiología , Genotipo , Isoniazida/farmacología , Mutación Missense , Mycobacterium tuberculosis/genética , Oxidorreductasas/genética , Mutación Puntual , Sensibilidad y Especificidad , Análisis de Secuencia de ADN , Tailandia/epidemiología , Tuberculosis/epidemiología , Tuberculosis Resistente a Múltiples Medicamentos/epidemiología , Tuberculosis Resistente a Múltiples Medicamentos/microbiologíaRESUMEN
BACKGROUND: The study documented Australian primigravidas' perceptions about breastfeeding. OBJECTIVES: To examine women's perspectives of their breastfeeding experiences during the first 12 weeks postpartum. DESIGN: A Journal was introduced to an intervention group (n=149) attending prenatal classes at a private hospital at 36 antenatal weeks. Using quantitative data at two days and 12 weeks postpartum, the intervention group was compared with a control group (n=154) that delivered at the same hospital. Qualitative data were also collected about the women's perceptions about breastfeeding to further illuminate their experience. Qualitative data from 203 women at two days postpartum and 252 women at 12 weeks postpartum represented the combined comments from the intervention and control groups. PARTICIPANTS: Participants were recruited as part of a randomised controlled trial of the effects of a Breastfeeding Journal on breastfeeding prevalence, self-efficacy, support, and influence from conflicting advice. The convenience sample of middle class, well-educated primiparous women from a Western Australian hospital had given birth to a singleton infant that was greater than 34 weeks gestation. METHODS: An open-ended question on a questionnaire sought mothers' comments about their breastfeeding experiences. Data were analysed using inductive content analysis. FINDINGS: These mothers described trying to 'get breastfeeding right'. Getting it right included enhancing factors, factors with mixed effect, and negative factors. CONCLUSIONS: Middle class mothers share breastfeeding perceptions with women in more vulnerable groups, including encountering conflicting and unhelpful advice and feeding pressures from health care professionals, family, and community members.
Asunto(s)
Adaptación Psicológica , Actitud Frente a la Salud , Lactancia Materna/psicología , Conocimientos, Actitudes y Práctica en Salud , Madres/psicología , Paridad , Adulto , Lactancia Materna/efectos adversos , Lactancia Materna/estadística & datos numéricos , Escolaridad , Femenino , Conducta de Ayuda , Humanos , Edad Materna , Madres/educación , Madres/estadística & datos numéricos , Rol de la Enfermera/psicología , Relaciones Enfermero-Paciente , Investigación Metodológica en Enfermería , Educación del Paciente como Asunto , Embarazo , Atención Prenatal , Investigación Cualitativa , Ensayos Clínicos Controlados Aleatorios como Asunto , Autoeficacia , Clase Social , Apoyo Social , Encuestas y Cuestionarios , Australia Occidental , EscrituraRESUMEN
The Bacillus subtilis HPB9 is the major heat-stable and acid-soluble protein associated with the nucleoid isolated at low ionic strength. The abundance of the protein in the cell is estimated to about 20,000 monomers per cell (Salti et al. (1985) J. Gen. Microbiol. 131, 581-590). The protein cross reacts specifically with the antiserum against the Bacillus globigii HBg. Moreover, HPB9 is able to introduce negative supercoiling in a relaxed covalently closed circular DNA, in the presence of topoisomerase I as demonstrated by one and two-dimensional electrophoresis. These results indicate that the nucleoid associated protein HPB9 is an HU-like protein and could be involved in the DNA compaction.
Asunto(s)
Bacillus subtilis/metabolismo , Proteínas Bacterianas/aislamiento & purificación , Proteínas de Unión al ADN/aislamiento & purificación , Secuencia de Aminoácidos , Proteínas Bacterianas/metabolismo , Núcleo Celular/metabolismo , Cromatografía Líquida de Alta Presión , Cromatografía por Intercambio Iónico , Reacciones Cruzadas , Electroforesis en Gel Bidimensional , Electroforesis en Gel de Poliacrilamida , Sueros Inmunes , Datos de Secuencia Molecular , Peso MolecularRESUMEN
Fusions of Bacillus subtilis protoplasts from two genetically marked strains produce noncomplementing heterodiploid bacteria. These noncomplementing diploids (Ncds) carry both parental chromosomes, but only one is expressed. Fusion products of strains polymorphic for NotI restriction sites provide new physical evidence to support the conclusion that Ncds are not an artifact of cross feeding or cell adhesion. We show that reversible chromosomal inactivation can only account for the biparental trait of unstable Ncds. Two types of cells were recovered from the late progeny of unstable Ncds: Ncds with irreversible chromosome silencing (stable Ncds) and secondary recombinants that displayed a genomic mosaic NotI profile. Segregants from an unstable Ncd population gave rise to two viable haploid cell types. By contrast, stable Ncds segregated into a population of viable and inviable haploid cells. We propose that the latter are derived from irreversible chromosome silencing. Our results indicate that clonal populations of stable Ncds are heterogenous and suggest that segregation and inactivation are independent parameters.
Asunto(s)
Bacillus subtilis/genética , Cromosomas Bacterianos , Diploidia , Bacillus subtilis/crecimiento & desarrollo , Fusión Celular , Intercambio Genético , ADN Bacteriano , Prueba de Complementación Genética , Haploidia , Protoplastos , Recombinación GenéticaRESUMEN
BACKGROUND: Some pathogenic bacteria are genetically very homogeneous, making strain discrimination difficult. In the last few years, tandem repeats have been increasingly recognized as markers of choice for genotyping a number of pathogens. The rapid evolution of these structures appears to contribute to the phenotypic flexibility of pathogens. The availability of whole-genome sequences has opened the way to the systematic evaluation of tandem repeats diversity and application to epidemiological studies. RESULTS: This report presents a database (http://minisatellites.u-psud.fr) of tandem repeats from publicly available bacterial genomes which facilitates the identification and selection of tandem repeats. We illustrate the use of this database by the characterization of minisatellites from two important human pathogens, Yersinia pestis and Bacillus anthracis. In order to avoid simple sequence contingency loci which may be of limited value as epidemiological markers, and to provide genotyping tools amenable to ordinary agarose gel electrophoresis, only tandem repeats with repeat units at least 9 bp long were evaluated. Yersinia pestis contains 64 such minisatellites in which the unit is repeated at least 7 times. An additional collection of 12 loci with at least 6 units, and a high internal conservation were also evaluated. Forty-nine are polymorphic among five Yersinia strains (twenty-five among three Y. pestis strains). Bacillus anthracis contains 30 comparable structures in which the unit is repeated at least 10 times. Half of these tandem repeats show polymorphism among the strains tested. CONCLUSIONS: Analysis of the currently available bacterial genome sequences classifies Bacillus anthracis and Yersinia pestis as having an average (approximately 30 per Mb) density of tandem repeat arrays longer than 100 bp when compared to the other bacterial genomes analysed to date. In both cases, testing a fraction of these sequences for polymorphism was sufficient to quickly develop a set of more than fifteen informative markers, some of which show a very high degree of polymorphism. In one instance, the polymorphism information content index reaches 0.82 with allele length covering a wide size range (600-1950 bp), and nine alleles resolved in the small number of independent Bacillus anthracis strains typed here.
Asunto(s)
Bacillus anthracis/genética , Genoma Bacteriano , Secuencias Repetidas en Tándem/genética , Yersinia pestis/genética , Bacillus anthracis/clasificación , ADN Bacteriano/análisis , Bases de Datos Factuales , Genotipo , Repeticiones de Minisatélite/genética , Reacción en Cadena de la Polimerasa , Polimorfismo Genético , Estadística como Asunto , Yersinia pestis/clasificaciónRESUMEN
OBJECTIVE: To describe the experience of ten couples who have had a home birth in Western Australia. DESIGN, SETTING AND PARTICIPANTS: Using a phenomenological approach, ten parent couples were interviewed and three home-birth videos observed. Of the ten couples, four discussed their first child's home birth. The remaining six couples had three or four children who had been born at home. FINDINGS: The essence of these parents' experiences of home birth was gained through identifying significant statements from transcripts and field notes and clustering these into the four themes of 'constructing the environment'; 'assuming control'; 'birthing'; and 'resolving expectations'. The first two themes were presented in a previous paper (Morison et al 1998). The latter two themes are now presented. The theme 'birthing' was where parents elaborated on their birth beliefs, discussed the actual birth and shared aspects of the relationship between the couple and the midwife. 'Resolving expectations' concerned the process of parents forming expectations, experiencing the reality of birth and then evaluating whether expectations were met. KEY CONCLUSIONS: The development of a supportive relationship between couples and their midwife was essential during this transition to parenthood. Resolving expectations was an essential process that the parents undertook to clarify the meaning of their birth experience, and thereby acknowledge its uniqueness. IMPLICATIONS FOR PRACTICE: The findings are important to midwives' practice as they reveal the value clients place on a shared philosophy about birth. Midwives, in any setting, can reflect on their own birthing beliefs and determine their compatibility with their clients' beliefs.
Asunto(s)
Parto Domiciliario/enfermería , Parto Domiciliario/psicología , Enfermeras Obstetrices/psicología , Relaciones Enfermero-Paciente , Padres/psicología , Satisfacción del Paciente , Actitud del Personal de Salud , Femenino , Humanos , Masculino , Investigación Metodológica en Enfermería , Filosofía en Enfermería , Embarazo , Apoyo Social , Encuestas y Cuestionarios , Australia OccidentalRESUMEN
OBJECTIVE: The purpose of this qualitative study was to describe the experience of couples who have had a home birth. DESIGN, SETTING AND PARTICIPANTS: A phenomenological approach was used to provide an understanding of the human experience of home birth in Western Australia. The research design consisted of a field study, in which 10 parent couples were interviewed and three videos of home births observed. Of the ten couples, four couples spoke of their first baby's home birth and the remaining six couples had three or four children who had been born at home. FINDINGS: The couples' experiences of home birth were gained through identifying significant statements from transcripts and field notes, and clustering these into the following four themes: 'constructing the environment'; 'assuming control'; 'birthing'; and 'resolving expectations'. The themes of 'constructing the environment' and 'assuming control' are described in detail in this paper. 'Constructing the environment' describes how couples adapted the physical environment, and established support to create a positive birth environment. 'Assuming control' discusses exerting control and taking responsibility for the birth. The remaining themes of 'birthing' and 'resolving expectations' are described in a subsequent paper (Morison et al, in press). KEY CONCLUSIONS: The research furnishes an insight into the couples' experience of home birth. The lived experience of birthing at home involved a process where a couple actively created an environment that enabled them to assume control and responsibility for the birth. IMPLICATIONS FOR PRACTICE: The findings are important for midwives in any setting, as they reveal the extent to which some parents value the right to assume control and responsibility for the birth of their baby. Although the physical environment of a home birth cannot be replicated in every setting, issues specific to the birth environment are relevant to all midwives.
Asunto(s)
Planificación Ambiental , Conocimientos, Actitudes y Práctica en Salud , Parto Domiciliario/psicología , Diseño Interior y Mobiliario , Control Interno-Externo , Padres/psicología , Poder Psicológico , Adulto , Conducta de Elección , Femenino , Parto Domiciliario/métodos , Parto Domiciliario/enfermería , Humanos , Masculino , Enfermeras Obstetrices/psicología , Relaciones Enfermero-Paciente , Investigación Metodológica en Enfermería , Padres/educación , Embarazo , Apoyo Social , Encuestas y Cuestionarios , Grabación de Cinta de Video , Australia OccidentalRESUMEN
OBJECTIVE: to describe women's perceptions of care in Western Australian birth centres following a previous hospital birth. DESIGN, SETTING AND PARTICIPANTS: an exploratory study was undertaken to examine the care experiences of women from three Western Australian birth centres. Data were obtained from 17 women whose interviews were audio-recorded and transcribed. The research focused upon women's perceptions of their recent birth centre care as compared to previous hospital care during childbirth. FINDINGS: four key themes emerged from the analysis: 'beliefs about pregnancy and birth', 'nature of the care relationship', 'care interactions' and 'care structures'. The themes of 'care interactions' and 'care structures' will be presented in this paper. Care interactions refer to women's opportunities to develop rapport with their carers. Care structures involved the organisational framework in which care was delivered. The first two themes of 'beliefs about pregnancy and birth' and the 'nature of the care relationship' were discussed in a previous paper. KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE: differences in opportunities for care interactions and care structures were revealed between birth centre and hospital settings. Ongoing, cumulative contacts with midwives in the birth-centre setting were strongly supported by women as encouraging the development of rapport and perception of 'being known' as an individual. Additionally, care structures tailored to women were advocated over the systematised, fragmented care found in hospital settings.
Asunto(s)
Actitud Frente a la Salud , Centros de Asistencia al Embarazo y al Parto/normas , Continuidad de la Atención al Paciente/normas , Salas de Parto/normas , Madres/psicología , Enfermeras Obstetrices/psicología , Enfermeras Obstetrices/normas , Relaciones Enfermero-Paciente , Adulto , Femenino , Humanos , Investigación en Evaluación de Enfermería , Investigación Metodológica en Enfermería , Atención Dirigida al Paciente/normas , Embarazo , Evaluación de Programas y Proyectos de Salud , Apoyo Social , Encuestas y Cuestionarios , Australia OccidentalRESUMEN
OBJECTIVE: to describe women's perceptions of care in Western Australian birth centres following a previous hospital birth. DESIGN, SETTING AND PARTICIPANTS: an exploratory design was used to study the care experiences of 17 women recruited from three Western Australian birth centres. Data were obtained from in-depth interviews that explored women's perceptions of their care in both the birth centre and hospital context. FINDINGS: four key themes emerged from the analysis: 'beliefs about pregnancy and birth', 'nature of the care relationship', 'care interactions', and 'care structures'. The themes of 'beliefs about pregnancy and birth' and 'nature of the care relationship' are discussed in this paper. Beliefs about pregnancy and birth refer to the philosophical underpinnings of pregnancy and birth held by women and their carers. Nature of the care relationship identifies women's perceptions of their relationship with health professionals. Care interactions and care structures will be described in a subsequent paper. KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE: The women's comments suggested differences in philosophy between hospital and birth-centre settings. The philosophy and beliefs of caregivers was an important component of the care experience. Women valued the normality of the birth-centre approach and the opportunity to experience the birth of their child with collaborative support from a midwife.
Asunto(s)
Actitud Frente a la Salud , Centros de Asistencia al Embarazo y al Parto/normas , Conducta Cooperativa , Salas de Parto/normas , Madres/psicología , Enfermeras Obstetrices/psicología , Enfermeras Obstetrices/normas , Relaciones Enfermero-Paciente , Adulto , Femenino , Humanos , Investigación en Evaluación de Enfermería , Investigación Metodológica en Enfermería , Filosofía en Enfermería , Embarazo , Evaluación de Programas y Proyectos de Salud , Calidad de la Atención de Salud , Encuestas y Cuestionarios , Australia OccidentalRESUMEN
The purpose of this study was to reveal the essence of role modelling in relation to learning in the clinical field from the nursing student's perspective. Twenty-one final year nursing undergraduates voluntarily and purposefully participated as informants in the study. Each participated in a face-to-face interview with a nurse researcher. In addition, a focus group interview session was conducted with seven of the participating students. Using the phenomenological method, the essence of role modelling emerged as a core theme which was linked to the students' clinical learning experiences. Multi-dimensional elements of learning that were contingent upon role modelling were categorised into five major themes: Expectations of self and others; Situational conditional factors; Situational anxiety--reality of fear/nervousness; Application of theoretical knowledge to practice; and, Experiential knowledge--an active learning process. The students' experiences of how role modelling impacted on their learning has implications for nursing education. It is necessary to acknowledge the variety of health carers, and in particular, the clinical nurse educator, who have consequential influences on student learning in the clinical field.
Asunto(s)
Competencia Clínica/normas , Bachillerato en Enfermería/métodos , Mentores/psicología , Rol , Estudiantes de Enfermería/psicología , Femenino , Grupos Focales , Humanos , Aprendizaje , Masculino , Modelos Educacionales , Investigación Metodológica en Enfermería , Encuestas y CuestionariosRESUMEN
A descriptive study was conducted to determine the criteria Western Australian mothers use to decide whether their breastfeeding was successful. Successful breastfeeding tends to be measured by duration with minimal research examining breastfeeding success from mothers' perspectives. Telephone interviews were conducted with 183 mothers who were asked to classify their breastfeeding as successful or unsuccessful and identify criteria used as a basis for their decision. Nineteen women (10 unsuccessful, 9 successful) were then interviewed in depth. Content analysis revealed breastfeeding success or failure to be a personally defined experience. Four categories of criteria used to determine breastfeeding success emerged: giving, persistence, meeting expectations and accomplishing personal goals. Nurses play a significant role in promoting breastfeeding. Therefore, encouraging understanding of the mother's perspective values the uniqueness of each experience and allows nurses to assess, acknowledge and reinforce a mother's perceptions of success.
Asunto(s)
Actitud Frente a la Salud , Lactancia Materna , Madres/psicología , Adulto , Australia , Investigación en Enfermería Clínica , Femenino , Humanos , Lactante , Recién Nacido , Factores Socioeconómicos , Encuestas y CuestionariosRESUMEN
Since very few tools used in health education are carefully evaluated, the aim of this study was to examine the effect that a breastfeeding information booklet had on breastfeeding behaviour. Feedback about breastfeeding information needs from a preliminary study of 58 Perth mothers at 3 months postpartum provided the basis for the development of an information booklet. The sample consisted of 150 mothers of full-term infants who were breastfeeding for the first time. Upon discharge from hospital, a random sample of 75 mothers were sent the booklet. These mothers and a control group (n = 75) were surveyed for 52 weeks to compare breastfeeding duration. Although the breastfeeding information booklet was found to be useful by 97% of the experimental group, there was no significant difference noted for breastfeeding duration between groups. Study findings have implications for clinical practice in highlighting the importance of breastfeeding information in increasing mothers' confidence, providing suggestions for breastfeeding practice, and helping mothers not to feel alone in their concerns. Further research should include investigations into the association between mothers reaching their intended goal for breastfeeding duration and being satisfied with the breastfeeding experience. Success with breastfeeding tends to be measured by duration alone, but no research to date has specifically examined the criteria mothers use to determine if their breastfeeding experience was successful.
Asunto(s)
Lactancia Materna , Educación del Paciente como Asunto/métodos , Materiales de Enseñanza , Lactancia Materna/estadística & datos numéricos , Femenino , Estudios de Seguimiento , Humanos , Educación del Paciente como Asunto/estadística & datos numéricos , Periodo Posparto , Análisis de Supervivencia , Factores de Tiempo , Australia OccidentalRESUMEN
A Bacillus subtilis integrational plasmid pVG4 (7.3 kb) was constructed. It was composed of a part of pBR322 (Ap, OriC), a part of pUB110 (Nm), and a part of the spoOA gene. The origin region of pUB110 had been deleted over 1.4 kb. Surprisingly, the replicative plasmids (8 kb) were generated by transformation of B. subtilis BG83 with pVG4 on selection with Nm. Analysis of the total DNA indicated the presence of repeated DNA and that pVG4 did not appear to integrate at the spoOA locus. The new replicon termed pYV exhibited a quite different restriction pattern from pVG4 due to dramatic DNA rearrangements. Although some components initially present in pVG4 were either present in pYV (Ap, oriC, and Nm) or lost (spoOA), other ones were newly gained such as a chromosomal fragment and a pUB110-type origin-like region. The latter was identified by restriction sites mapping and limited sequence analyses. By PCR amplification, the origin region of pYV was shown to be present as a cryptic sequence in the chromosome of strain BG83. The chromosomal fragment integrated into pYV was at least 0.25 kb long and located in a 19-kb SfiI fragment mapping at 106 degrees. We propose that the establishment of the new replicon pYV is the result of a genetic recombination between the pUB110 part present in the integrational plasmid pVG4 and the cryptic origin region of pUB110 harbored in the chromosome of the recipient strain BG83 in relation with a particular role of neomycin selection.
Asunto(s)
Bacillus subtilis/genética , Factores R/genética , Replicón/genética , Bacillus subtilis/efectos de los fármacos , Secuencia de Bases , ADN Bacteriano/genética , Farmacorresistencia Microbiana/genética , Datos de Secuencia Molecular , Neomicina/farmacología , Mapeo Restrictivo , Transformación GenéticaRESUMEN
Epigenetic mechanisms are not exclusively reserved to eukaryotic organisms. They are also observed in prokaryotes. As described first by Hotchkiss and Gabor, protoplast fusion between strains of Bacillus subtilis produces heterodiploid cells. Heterodiploidy is associated with the inactivation of one of the chromosomes. To study the physical structure of the fusion product and the molecular mechanisms of inactivation, we constructed heterodiploid clones containing two chromosomes labeled by a NotI restriction fragment length polymorphism. In the progeny, we identified haploid recombinant clones that contain a chromosome carrying large regions of inactivated DNA. Studies of both recombinants of the latter kind and heterodiploid cells indicated that chromosomal inactivation was not determined by alteration of the inactivated nucleotide sequence, but was probably due to a modification in the structure of the bacterial chromatin.
Asunto(s)
Bacillus subtilis/genética , Cromosomas Bacterianos , Regulación Bacteriana de la Expresión Génica , Modelos Genéticos , Proteínas Bacterianas/genética , Desoxirribonucleasas de Localización Especificada Tipo II , Operón , Células Procariotas , Purinas , Recombinación Genética , Factores de Transcripción/genéticaRESUMEN
Microsatellites and minisatellites are two classes of tandem repeat sequences differing in their size, mutation processes, and chromosomal distribution. The boundary between the two classes is not defined. We have developed a convenient, hybridization-based human library screening procedure able to detect long CA-rich sequences. Analysis of cosmid clones derived from a chromosome 1 library show that cross-hybridizing sequences tested are imperfect CA-rich sequences, some of them showing a minisatellite organization. All but one of the 13 positive chromosome 1 clones studied are localized in chromosomal bands to which minisatellites have previously been assigned, such as the 1pter cluster. To test the applicability of the procedure to minisatellite detection on a larger scale, we then used a large-insert whole-genome PAC library. Altogether, 22 new minisatellites have been identified in positive PAC and cosmid clones and 20 of them are telomeric. Among the 42 positive PAC clones localized within the human genome by FISH and/or linkage analysis, 25 (60%) are assigned to a terminal band of the karyotype, 4 (9%) are juxtacentromeric, and 13 (31%) are interstitial. The localization of at least two of the interstitial PAC clones corresponds to previously characterized minisatellite-containing regions and/or ancestrally telomeric bands, in agreement with this minisatellite-like distribution. The data obtained are in close agreement with the parallel investigation of human genome sequence data and suggest that long human (CA)s are imperfect CA repeats belonging to the minisatellite class of sequences. This approach provides a new tool to efficiently target genomic clones originating from subtelomeric domains, from which minisatellite sequences can readily be obtained. [The sequence data described in this paper have been submitted to the EMBL data library under accession nos. AJ000377-AJ000383.]