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1.
Eur J Dent Educ ; 21(2): 108-112, 2017 May.
Artículo en Inglés | MEDLINE | ID: mdl-26901809

RESUMEN

It is important for dental schools to select students who will complete their degree and progress on to become the dentists of the future. The process should be transparent, fair and ethical and utilise selection tools that select appropriate students. The interview is an integral part of UK dental schools student selection procedures. OBJECTIVE: This study was undertaken in order to determine whether different interview methods (Cardiff with a multiple mini interview and Newcastle with a more traditional interview process) along with other components used in selection predicted academic performance in students. METHODS: The admissions selection data for two dental schools (Cardiff and Newcastle) were collected and analysed alongside student performance in academic examinations in Year 1 of the respective schools. Correlation statistics were used to determine whether selection tools had any relevance to academic performance once students were admitted to their respective Universities. RESULTS: Data was available for a total of 177 students (77 Cardiff and 100 Newcastle). Examination performance did not correlate with admission interview scores at either school; however UKCAT score was linked to poor academic performance. DISCUSSION: Although interview methodology does not appear to correlate with academic performance it remains an integral and very necessary part of the admissions process. Ultimately schools need to be comfortable with their admissions procedures in attracting and selecting the calibre of students they desire.


Asunto(s)
Rendimiento Académico , Entrevistas como Asunto , Criterios de Admisión Escolar , Facultades de Odontología , Estudiantes de Odontología , Femenino , Humanos , Masculino , Reino Unido
2.
Br Dent J ; 216(4): 191-6, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24557393

RESUMEN

The United Kingdom Clinical Aptitude Test (UKCAT) has now been an active part of U.K. dental admissions for seven years with the test being used by 11 dental schools within their admissions processes. This paper gives an overview on UKCAT and highlights some of the on-going work in relation to its development. This paper also highlights what UKCAT is and some developments with respect to the UKCAT. It also facilitates the process of keeping dental practitioners informed.


Asunto(s)
Competencia Clínica , Criterios de Admisión Escolar , Facultades de Odontología , Reino Unido
3.
Br Dent J ; 215(11): 565-70, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-24309789

RESUMEN

OBJECTIVE: This research details and quantifies applicants' perceptions towards multiple mini-interviews as a selection tool. MATERIALS AND METHODS: BDS and DCP (therapy and hygiene) candidates who secured a multiple mini-interview (MMI) completed a questionnaire based on the thematic analysis of the previous year's multiple mini-interviews. The questionnaire explored the candidates' feelings with reference to the interview process and the stations used on the MMI process. RESULTS: Of 235 BDS and 62 therapy and hygiene interviewees, 231 (98.3%) and 61 (96.7%) completed or partially completed the questionnaire. Demographic data revealed that 61.9% (143) of the BDS interviewees were female and 86.7% were female (52) in the therapy and hygiene cohort. The majority of interviewees came from schools in England and received a state education. While 69.6% of the BDS interviewees had experience of an interview before their MMI, this was down to 58.3% in the hygiene and therapy interviewees. Binomial statistical calculations and chi-squared tests of independence of categorical variables on nominally scaled data revealed statistically significant differences (p >0.001) and both groups of students were positive regarding the selection process (p >0.001). Overall there was similarity between groups with respect to the themes evaluated and stations used in the MMI process, however, statistical analysis did highlight areas of difference. There were 54 separate free text comments recorded but qualitative analysis failed to identify any themes that had not been previously identified. CONCLUSION: This research did not reveal any new emergent themes in relation to the MMI process between two different cohorts of students but did reveal general similarities and some specific areas of difference.


Asunto(s)
Higienistas Dentales/educación , Educación en Odontología , Entrevistas como Asunto , Criterios de Admisión Escolar , Estudiantes de Odontología , Inglaterra , Femenino , Humanos , Masculino
5.
J Neurosci Methods ; 207(1): 86-90, 2012 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-22498201

RESUMEN

While neural recording chambers for non-human primates can be purchased commercially, these generic chambers do not contour to the animal's skull. In order to seal gaps, a cap of dental acrylic (methyl methacrylate) is often applied around the chamber. There are multiple disadvantages associated with this method. Applying acrylic delays and further complicates surgical procedure, and overheating during the curing process can cause damage to the bone. Post-surgery, acrylic margins can give rise to bacterial growth and infection. Here we describe a method to develop custom implants which conform to the individual's skull, thereby eliminating the need for acrylic. This method shortens surgery time and significantly improves the hygiene of chamber margins.


Asunto(s)
Diseño Asistido por Computadora , Neurofisiología/instrumentación , Prótesis e Implantes , Animales , Diseño de Equipo , Macaca mulatta , Masculino , Cráneo/anatomía & histología
6.
Br Dent J ; 212(7): 331-5, 2012 Apr 13.
Artículo en Inglés | MEDLINE | ID: mdl-22498535

RESUMEN

OBJECTIVE: This research evaluated the mutliple mini-interview (MMI) process as part of the admissions procedure for a dental school. DESIGN: The thematic analysis of a paper-based questionnaire. MATERIALS AND METHODS: Following screening an MMI was arranged for 190 candidates applying to study dentistry with written feedback obtained from candidates and interviewers. RESULTS: A 100% response rate to the paper-based questionnaire was achieved for candidates and a 90% response rate was obtained from interviewers. With specific reference to how candidates perceived their performance, 127 (67.9%) felt they had performed well with 24 (19.3%) unsure and 36 (12.8%) saying their performance was not ideal. Candidates generally thought that they had prepared as well as they could have done for the MMIs and 146 (77.2%) thought that they had done enough at interview to merit being offered a place to study dentistry. The MMI experience was considered favourable and from 137 written comments received by candidates 39 were most positive with reference to the MMIs. A thematic analysis of the comments identified a number of emergent themes including lack of control, anxiety and nervousness, preparedness and comparisons with conventional interviews. CONCLUSION: The MMI appears to be useful in the selection of dental students.


Asunto(s)
Entrevistas como Asunto/métodos , Criterios de Admisión Escolar , Facultades de Odontología/organización & administración , Estudiantes de Odontología , Femenino , Humanos , Masculino , Encuestas y Cuestionarios , Reino Unido
7.
Eur J Dent Educ ; 16(1): e117-21, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22251334

RESUMEN

INTRODUCTION: Dental patient records should be of high quality, contain information to allow for good continuity of care and clinical defence (should the need ever arise) and, ideally, facilitate clinical audit. Handwritten dental records have been assessed for their compliance to statutory regulations, but the same cannot be levelled at computer-generated notes. This study aimed to compare and analyse the compliance of both methods of data recording with statutory regulations. METHOD: Fifty consecutive sets of handwritten notes and 50 sets of computer-generated notes were audited for compliance with a number of legal requirements and desirable characteristics for dental records and the results compared. The standard set for compliance with all characteristics was 100%. RESULTS: The computer-generated notes satisfied the set standard for 8 of the 11 legal requirements and three of six desirable characteristics. The handwritten notes satisfied the set standard for 1 of 11 legal requirements and none of the desirable characteristics. A statistical difference (using a 95% confidence interval) between the two methods was observed in 5 of 11 legal characteristics and three of six desirable characteristics, all of which were in favour of computer-generated notes. CONCLUSIONS: Within the limitations of this study, computer-generated notes achieved a much higher compliance rate with the set parameters, making defence in cases of litigation, continuity of care and clinical audit easier and more efficient.


Asunto(s)
Computadores , Registros Odontológicos/legislación & jurisprudencia , Registros Odontológicos/normas , Control de Formularios y Registros/legislación & jurisprudencia , Control de Formularios y Registros/normas , Escritura , Intervalos de Confianza , Humanos , Control de Calidad , Estudios Retrospectivos , Reino Unido
8.
Br Dent J ; 211(4): 163-6, 2011 Aug 26.
Artículo en Inglés | MEDLINE | ID: mdl-21869790

RESUMEN

Decontamination of dental instruments has recently been the subject of considerable debate. However, little information is available on the potential bacterial colonisation of dental appliances returning from dental laboratories and their need for decontamination. This study investigated the extent and nature of microbial contamination of removable prosthodontic appliances produced at different dental laboratories and stored in two clinical teaching units (CTU 1 and CTU 2) of a dental hospital and school. Forty consecutive dental prosthodontic appliances that were being stored under varying conditions in the two clinical teaching units were selected for study; the appliances having been produced 'in-house' (hospital laboratory) or 'out-of-house' (external commercial laboratory). Two appliances, that were known to have undergone decontamination before storage, were used as controls. Swabs were taken according to a standard protocol and transferred to the microbiological laboratory with bacterial growth expressed as colony forming units (cfu) per cm(2). Microbial sampling yielded growth from 23 (58%) of the 40 appliances studied (CTU 1, n = 22; CTU 2, n = 18), with 38% of these having a high level of contamination (>42,000 cfu/cm(2)). The predominant bacteria isolated were Bacillus spp. (57%), pseudomonads (22%) and staphylococci (13%). Fungi of the genus Candida were detected in 38% of the samples. There was no significant difference in contamination of the appliances in relation to either their place of production or the CTU (p >0.05). However, the level of contamination was significantly higher (p = 0.035) for those appliances stored in plastic bag with fluid (n = 16) compared to those stored on models (n = 19). No growth was recovered from the two appliances that had undergone decontamination before storage. The research showed that appliances received from laboratories are often contaminated and therefore there is a need for routine disinfection of such items before use and a review of storage conditions required.


Asunto(s)
Dentadura Completa/microbiología , Dentadura Parcial Removible/microbiología , Contaminación de Equipos , Laboratorios Odontológicos , Resinas Acrílicas , Bacillus/crecimiento & desarrollo , Carga Bacteriana , Candida/crecimiento & desarrollo , Aleaciones de Cromo , Materiales Dentales , Servicio Odontológico Hospitalario , Desinfección , Hospitales de Enseñanza , Humanos , Inmersión , Staphylococcus aureus Resistente a Meticilina/crecimiento & desarrollo , Modelos Dentales , Pseudomonas/crecimiento & desarrollo , Facultades de Odontología , Staphylococcus/crecimiento & desarrollo , Propiedades de Superficie , Factores de Tiempo , Ceras
9.
Br Dent J ; 210(8): E12, 2011 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-21508989

RESUMEN

This study investigated the effects that disposable infection control barriers and physical damage through use had on the power output from dental light curing units (LCUs) and light curing tips (LCTs). Five disposable infection control barriers were tested on a number of LCUs and LCTs. Testing involved the repeated measurement of power output of LCUs and LCTs on a radiometer. Two of the barriers tested caused statistically significant reductions in the mean light output intensity when compared to the no barrier control groups. One barrier type reduced the power output by 30 to 40%. It was also noted that physical damage to the LCTs affected power output by between 20 and 30%, which was then further reduced by the disposable barrier. This study showed that three of the five disposable infection control barriers had little effect on the overall efficiency of the power output of the LCUs. It also showed that physical damage to LCUs and LCTs can affect power output significantly. Infection control measures should be carefully considered before use to avoid undue effects on power output delivered from the LCUs/LCTs to ensure that the degree of polymerisation within the resin-based composite and curing efficiency are not affected unduly.


Asunto(s)
Luces de Curación Dental , Equipos Desechables , Control de Infección Dental/instrumentación , Luces de Curación Dental/clasificación , Contaminación de Equipos/prevención & control , Diseño de Equipo , Falla de Equipo , Humanos , Luz , Polimerizacion , Equipos de Seguridad/clasificación , Dosis de Radiación , Radiometría , Esterilización/métodos , Propiedades de Superficie
10.
J Oral Rehabil ; 38(1): 72-8, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-20626573

RESUMEN

The aim of this project was to examine tooth preparations made by general dental practitioners (GDPs) for occlusal and cingulum rest seats for cobalt-chromium removable partial dentures (RPDs). Master casts and prescribed denture designs for cobalt-chromium RPDs produced by a commercial dental laboratory from impressions made by 45 GDPs across Wales were evaluated over a period of 5 months. Rest seats and associated interocclusal clearances were assessed using pre-determined criteria. A total of 68 casts were examined. Of these, 33 did not have rest seats included in their prescription. Of the remaining 35 casts, 81 rests had been prescribed of which only 24 (30%) had signs of tooth preparations for these rest seats. Using pre-determined criteria, 60% of rest seats were under-prepared in the mesio-distal plane and 30% were over-prepared in the bucco-lingual plane. In 17 cases where natural teeth opposed the rest seat, the mean interocclusal clearance was 1·5 mm (range 0·6-3·5 mm) with 6 of the 17 rests (35%) being less than the recommended thickness. In total, 18 of the 24 rests prepared did not meet the criteria, and 11 of the 21 rests prescribed had no obvious preparation and insufficient occlusal clearance. Where prescribed, the majority of rests did not meet the identified criteria. The rest seat preparations varied greatly in all planes including the interocclusal clearance. Further emphasis should be given to aspects of denture design in undergraduate and continuing education programmes for dentists.


Asunto(s)
Dentadura Parcial Removible , Odontología General , Preparación Protodóncica del Diente/métodos , Cromo , Cobalto , Pilares Dentales , Análisis del Estrés Dental , Diseño de Dentadura , Retención de Dentadura/métodos , Humanos , Modelos Dentales
11.
Eur J Prosthodont Restor Dent ; 18(1): 31-2, 2010 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-20397500

RESUMEN

This article represents the consensus from a meeting of the British Society of Prosthetic Dentistry's Education Group which met to discuss implant dentistry at the undergraduate student level. The consensus recognises the need to embed the teaching of implant supported prostheses if such a treatment modality is to be widely practised after graduation. This short article makes some recommendations as well as detailing some challenges and barriers that need to be overcome if implant dentistry is to be successfully embedded in an undergraduate dental curriculum.

12.
Br Dent J ; 208(1): 9-10, 2010 Jan 09.
Artículo en Inglés | MEDLINE | ID: mdl-20057450

RESUMEN

This article represents the consensus from a meeting of the British Society of Prosthetic Dentistry's Education Group which met to discuss implant dentistry at the undergraduate dental student level. The consensus recognises the need to embed the teaching of implant supported prostheses if such a treatment modality is to be widely practised after graduation. This short article makes some recommendations as well as detailing some challenges and barriers that need to be overcome if implant dentistry is to be successfully embedded in an undergraduate dental curriculum.


Asunto(s)
Conferencias de Consenso como Asunto , Implantes Dentales , Educación en Odontología , Prostodoncia/educación , Competencia Clínica , Curriculum , Prótesis Dental de Soporte Implantado , Humanos , Planificación de Atención al Paciente , Desarrollo de Programa , Enseñanza/métodos , Reino Unido
13.
J Inherit Metab Dis ; 31(6): 761-8, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18937046

RESUMEN

Dimethylglycine dehydrogenase (DMGDH) is a mitochondrial matrix flavoprotein that catalyses the demethylation of dimethylglycine to form sarcosine, accompanied by the reduction of the covalently bound FAD cofactor. Electron-transfer flavoprotein reoxidizes the reduced flavin and transfers reducing equivalents to the main mitochondrial respiratory chain through the enzyme ETF-ubiquinone oxidoreductase. DMGDH plays a prominent role in choline and 1-carbon metabolism. We have expressed the mature form of human DMGDH and the H109R variant identified in a DMGDH-deficient patient as N-terminally His(6)-tagged proteins in E. coli. The enzymes were purified to homogeneity by nickel affinity and anion exchange chromatography. The presence of FAD in the wild-type enzyme was confirmed by spectrophotometric analysis. The H109R variant, however, had only 47% of the wild-type level of bound flavin as expressed in E. coli, indicating its reduced affinity for FAD As previously described for rat enzyme studies, the wild-type human enzyme exhibited two K (m) values for N,N-dimethylglycine (K (m1) = 0.039 +/- 0.010 mmol/L and K(m2) = 15.4 +/- 1.2 mmol/L). The addition of 4 micromol/L tetrahydrofolate resulted in a slight decrease in specific activity and a substantial decrease in K (m2) (1.10 +/- 0.55 mmol/L). The flavinated H109R variant protein exhibited a 27-fold decrease in specific activity and a 65-fold increase in K (m), explaining its pathogenicity. Additionally, the current expression system represents a significant improvement over a previously described rat DMGDH expression system and will enhance our ability to further study this important metabolic enzyme.


Asunto(s)
Dimetilglicina-Deshidrogenasa/deficiencia , Dimetilglicina-Deshidrogenasa/genética , Errores Innatos del Metabolismo/genética , Cromatografía por Intercambio Iónico/métodos , Dimetilglicina-Deshidrogenasa/química , Relación Dosis-Respuesta a Droga , Electrones , Flavina-Adenina Dinucleótido/metabolismo , Flavoproteínas/metabolismo , Humanos , Cinética , Errores Innatos del Metabolismo/diagnóstico , Modelos Químicos , Mutación , Oxígeno/metabolismo , Proteínas Recombinantes/metabolismo , Sarcosina-Deshidrogenasa/metabolismo , Espectrofotometría/métodos
14.
Am J Hum Genet ; 81(6): 1133-43, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17999356

RESUMEN

Very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency is an inborn mitochondrial fatty-acid beta-oxidation (FAO) defect associated with a broad mutational spectrum, with phenotypes ranging from fatal cardiopathy in infancy to adolescent-onset myopathy, and for which there is no established treatment. Recent data suggest that bezafibrate could improve the FAO capacities in beta-oxidation-deficient cells, by enhancing the residual level of mutant enzyme activity via gene-expression stimulation. Since VLCAD-deficient patients frequently harbor missense mutations with unpredictable effects on enzyme activity, we investigated the response to bezafibrate as a function of genotype in 33 VLCAD-deficient fibroblasts representing 45 different mutations. Treatment with bezafibrate (400 microM for 48 h) resulted in a marked increase in FAO capacities, often leading to restoration of normal values, for 21 genotypes that mainly corresponded to patients with the myopathic phenotype. In contrast, bezafibrate induced no changes in FAO for 11 genotypes corresponding to severe neonatal or infantile phenotypes. This pattern of response was not due to differential inductions of VLCAD messenger RNA, as shown by quantitative real-time polymerase chain reaction, but reflected variable increases in measured VLCAD residual enzyme activity in response to bezafibrate. Genotype cross-analysis allowed the identification of alleles carrying missense mutations, which could account for these different pharmacological profiles and, on this basis, led to the characterization of 9 mild and 11 severe missense mutations. Altogether, the responses to bezafibrate reflected the severity of the metabolic blockage in various genotypes, which appeared to be correlated with the phenotype, thus providing a new approach for analysis of genetic heterogeneity. Finally, this study emphasizes the potential of bezafibrate, a widely prescribed hypolipidemic drug, for the correction of VLCAD deficiency and exemplifies the integration of molecular information in a therapeutic strategy.


Asunto(s)
Acil-CoA Deshidrogenasa de Cadena Larga/deficiencia , Acil-CoA Deshidrogenasa de Cadena Larga/genética , Bezafibrato/uso terapéutico , Hipolipemiantes/uso terapéutico , Errores Innatos del Metabolismo Lipídico/genética , Acil-CoA Deshidrogenasa de Cadena Larga/química , Acil-CoA Deshidrogenasa de Cadena Larga/metabolismo , Animales , Células Cultivadas , Ácidos Grasos/metabolismo , Fibroblastos/citología , Fibroblastos/efectos de los fármacos , Fibroblastos/enzimología , Fibroblastos/patología , Terapia Genética/métodos , Genotipo , Humanos , Errores Innatos del Metabolismo Lipídico/enzimología , Modelos Moleculares , Reacción en Cadena de la Polimerasa , ARN Mensajero/genética , Ratas , Piel/citología , Piel/enzimología , Piel/patología
15.
Br Dent J ; 200(11): 621-3; discussion 617, 2006 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-16767140

RESUMEN

OBJECTIVES: To discover what dentists require of a hospital response letter with regards to content and timeliness. DESIGN: Postal survey. SETTING: South Wales. SUBJECTS AND METHODS: A postal questionnaire was issued to all dentists (n = 256) who had referred a patient to the dental hospital between 1 January 2003 and 1 March 2003. RESULTS: The response rate was 60.2% (154). The preferred time frame for the receipt of a letter following a patient's appointment was one to three weeks for 96.4% (n = 133) of respondents, but 58.4% believed that they currently do not receive responses within this time frame. The preferred method of communication remained the letter (n = 82, 53%), followed by the telephone (n = 58, 38%). E-mail accounted for eight percent (n = 12) of communication. Most respondents (70%, n = 107) were satisfied with the letters' content. Eight of the ten items of information suggested as being appropriate in a response letter were considered essential by 53.2% of dentists (n = 82), and 55.8% (n = 76) believed the remaining two items to be desirable. CONCLUSIONS: Dentists agree closely on the information required in a response letter and most are satisfied with the content of current response letters. However, many dentists believe response letters arrive later than three weeks after their patient's appointment.


Asunto(s)
Servicio Odontológico Hospitalario , Retroalimentación , Odontología General/estadística & datos numéricos , Relaciones Interprofesionales , Derivación y Consulta , Correspondencia como Asunto , Humanos , Encuestas y Cuestionarios , Factores de Tiempo , Gales
17.
J Dent ; 34(1): 67-76, 2006 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-15982795

RESUMEN

OBJECTIVES: Fruit teas are know to have an erosive effect on enamel, but the effects on dentine are unknown. Lesions of dentine hypersensitivity have numerous patent dentinal tubules and the aim of this paper was to examine the ability of various fruit teas to remove the smear layer. METHODS: The erosive potential of a variety of fruit teas was assessed in the laboratory by measuring their pH and neutralisable acidity. Smeared dentine specimens were prepared from extracted teeth and the ability of each tea to remove the smear layer was assessed by measuring the diameter and area of the opened tubules and counting the number of patent tubules seen in a unit area using scanning electron microscopy. A 0.2% citric acid solution was used as a positive control. RESULTS: The pH of the fruit teas ranged from 2.98 to 3.95 and the neutralisable acidity ranged from 10.63 to 33.0 ml of 0.1 M NaOH. All the fruit teas tested were able to remove the smear layer. The mean diameter of the tubules ranged from 0.61 to 1.14 microm and the mean area ranged from 0.31 to 1.03 microm2. The number of patent tubules per specimen ranged from 13 to 121. CONCLUSION: All the fruit teas tested were found to be highly acidic and able to remove the smear layer.


Asunto(s)
Esmalte Dental/efectos de los fármacos , Dentina/efectos de los fármacos , Frutas/efectos adversos , Capa de Barro Dentinario , Té/efectos adversos , Esmalte Dental/ultraestructura , Dentina/ultraestructura , Frutas/química , Humanos , Concentración de Iones de Hidrógeno , Té/química , Erosión de los Dientes/inducido químicamente
18.
Br Dent J ; 198(5): 259-60, 2005 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-15870742

RESUMEN

The internet is becoming a more and more powerful tool and many dental practitioners use it to advertise their dental service; some dental practices even offer on-line appointment booking! It is not unreasonable to surmise that use of the internet is likely to become increasingly common practice by dentists in the future. This is not surprising as the World Wide Web (WWW) provides an opportunity for dentists to advertise themselves and their practices to a wide audience in a relatively economical manner.


Asunto(s)
Publicidad/legislación & jurisprudencia , Internet/legislación & jurisprudencia , Administración de la Práctica Odontológica/legislación & jurisprudencia , Regulación Gubernamental , Humanos , Reino Unido
19.
Plant Physiol ; 127(4): 1656-66, 2001 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-11743110

RESUMEN

Chloroplast division is driven by a macromolecular complex containing components that are positioned on the cytosolic surface of the outer envelope, the stromal surface of the inner envelope, and in the intermembrane space. The only constituents of the division apparatus identified thus far are the tubulin-like proteins FtsZ1 and FtsZ2, which colocalize to rings at the plastid division site. However, the precise positioning of these rings relative to the envelope membranes and to each other has not been previously defined. Using newly isolated cDNAs with open reading frames longer than those reported previously, we demonstrate here that both FtsZ2 proteins in Arabidopsis, like FtsZ1 proteins, contain cleavable transit peptides that target them across the outer envelope membrane. To determine their topological arrangement, protease protection experiments designed to distinguish between stromal and intermembrane space localization were performed on both in vitro imported and endogenous forms of FtsZ1 and FtsZ2. Both proteins were shown to reside in the stromal compartment of the chloroplast, indicating that the FtsZ1- and FtsZ2-containing rings have similar topologies and may physically interact. Consistent with this hypothesis, double immunofluorescence labeling of various plastid division mutants revealed precise colocalization of FtsZ1 and FtsZ2, even when their levels and assembly patterns were perturbed. Overexpression of FtsZ2 in transgenic Arabidopsis inhibited plastid division in a dose-dependent manner, suggesting that the stoichiometry between FtsZ1 and FtsZ2 is an important aspect of their function. These studies raise new questions concerning the functional and evolutionary significance of two distinct but colocalized forms of FtsZ in plants and establish a revised framework within which to understand the molecular architecture of the plastid division apparatus in higher plants.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Cloroplastos/genética , Pisum sativum/metabolismo , Proteínas de Plantas/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Cloroplastos/metabolismo , Endopeptidasas/metabolismo , Técnica del Anticuerpo Fluorescente , Sistemas de Lectura Abierta , Pisum sativum/genética , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente
20.
J Cell Biol ; 153(1): 111-20, 2001 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-11285278

RESUMEN

Among the events that accompanied the evolution of chloroplasts from their endosymbiotic ancestors was the host cell recruitment of the prokaryotic cell division protein FtsZ to function in chloroplast division. FtsZ, a structural homologue of tubulin, mediates cell division in bacteria by assembling into a ring at the midcell division site. In higher plants, two nuclear-encoded forms of FtsZ, FtsZ1 and FtsZ2, play essential and functionally distinct roles in chloroplast division, but whether this involves ring formation at the division site has not been determined previously. Using immunofluorescence microscopy and expression of green fluorescent protein fusion proteins in Arabidopsis thaliana, we demonstrate here that FtsZ1 and FtsZ2 localize to coaligned rings at the chloroplast midpoint. Antibodies specific for recognition of FtsZ1 or FtsZ2 proteins in Arabidopsis also recognize related polypeptides and detect midplastid rings in pea and tobacco, suggesting that midplastid ring formation by FtsZ1 and FtsZ2 is universal among flowering plants. Perturbation in the level of either protein in transgenic plants is accompanied by plastid division defects and assembly of FtsZ1 and FtsZ2 into filaments and filament networks not observed in wild-type, suggesting that previously described FtsZ-containing cytoskeletal-like networks in chloroplasts may be artifacts of FtsZ overexpression.


Asunto(s)
Cloroplastos/metabolismo , Proteínas de Plantas/metabolismo , Animales , Arabidopsis , Proteínas de Arabidopsis , Proteínas Fluorescentes Verdes , Proteínas Luminiscentes/metabolismo , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Plastidios/metabolismo , Conejos , Proteínas Recombinantes de Fusión/metabolismo
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