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1.
Clin Otolaryngol ; 43(6): 1522-1527, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30058276

RESUMO

OBJECTIVE: In patients with nasal polyposis (NP), otitis media with effusion (OME) seems to be a marker of severity of the inflammatory process occurring in those patients. The aim was to assess whether OME could represent a marker of resistance to the surgical treatment of NP. DESIGN: Longitudinal observational cohort study including patients between January 1991 and January 2017. Mean follow-up was 7.4 years. SETTING: Tertiary-care hospital centre. PARTICIPANTS: Patients with NP who underwent surgery (radical bilateral sphenoethmoidectomy). MAIN OUTCOME MEASURES: Four outcomes reflecting resistance to the surgical treatment: a clinical score of rhinologic symptoms, the mean number of systemic corticosteroids treatment per year, the recurrence rate of polyps and the rate of reoperation. RESULTS: A total of 266 patients were included (63.9% of men, mean age 48 years). In multivariate linear mixed-effects regression, when compared to patients without OME, patients with OME presented a similar clinical score of symptoms (coefficient 0.09, 95% confidence interval (CI) -0.25 to 0.06, P-value = 0.24) and a borderline higher mean number of systemic corticosteroids treatments per year (coefficient 0.11, 95% CI 0.003-0.23, P-value = 0.04). In multivariate Cox regression analyses, patients with OME had a similar reoperation rate than patients without OME (hazard ratio (HR) 0.29, 95% CI 0.06-1.50) and a similar recurrence rate of polyps (HR 0.59, 95% CI 0.23-1.53). CONCLUSION: In patients with NP, OME is not a marker of surgical resistance. Those patients should be managed similarly than patients without, and similar outcomes following surgery should be expected.


Assuntos
Pólipos Nasais/complicações , Otite Média com Derrame/cirurgia , Procedimentos Cirúrgicos Otológicos/métodos , Endoscopia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Pólipos Nasais/diagnóstico , Pólipos Nasais/cirurgia , Otite Média com Derrame/diagnóstico , Otite Média com Derrame/etiologia , Otoscopia/métodos , Estudos Retrospectivos , Fatores de Tempo , Resultado do Tratamento
3.
Eur Arch Otorhinolaryngol ; 273(8): 2019-26, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26329899

RESUMO

The objective of this study was to investigate the usefulness of auditory steady-state responses (ASSRs) for estimating hearing thresholds in young children, compared with behavioural thresholds. The second objective was to investigate ASSR thresholds obtained with insert earphones versus supra-aural headphones to determine which transducer produces ASSR thresholds most similar to behavioural thresholds measured with supra-aural headphones. This retrospective study included 29 participants (58 ears): 12 children (24 ears) in the insert group and 17 children (34 ears) in the supra-aural group. No general anaesthesia was used. For both groups, there was a strong correlation between behavioural and ASSR thresholds, with a stronger correlation for the insert group. When behavioural thresholds are difficult to obtain, ASSR may be a useful objective measure that can be combined with other audiometric procedures to estimate hearing thresholds and to determine appropriate auditory rehabilitation approaches.


Assuntos
Limiar Auditivo/fisiologia , Comportamento Infantil/fisiologia , Perda Auditiva , Transdutores , Audiometria/instrumentação , Audiometria/métodos , Pré-Escolar , Pesquisa Comparativa da Efetividade , Feminino , Perda Auditiva/diagnóstico , Perda Auditiva/psicologia , Humanos , Lactente , Masculino , Estudos Retrospectivos , Transdutores/classificação , Transdutores/normas
4.
Opt Lett ; 38(21): 4457-60, 2013 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-24177118

RESUMO

Phase matching in a multilayer AlGaAs waveguide is used to generate mid-IR (7.5-8.5 µm) light through difference frequency generation (DFG) between a 1550 nm pump and 1950 nm signal. This represents the longest wavelength generated through DFG in a 2D waveguide mode in a semiconductor waveguide. It was produced with an efficiency of 1.2×10(-4) %/W in a 1 mm long sample. The process is shown to be tunable across >2 µm through appropriate tuning of the input pump and signal wavelengths and/or waveguide geometry, and is therefore a viable platform for monolithic, tunable, mid-IR sources.

5.
Eur Ann Otorhinolaryngol Head Neck Dis ; 136(2): 135-140, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30482706

RESUMO

Based on a review of the medical literature, the authors document the key technical points, variants, technical errors to avoid and main functional results of lateral pharyngotomy for resection of cancers originating from the lateral oro and/or hypopharynx.


Assuntos
Neoplasias Faríngeas/cirurgia , Faringe/cirurgia , Pontos de Referência Anatômicos , Humanos , Ilustração Médica , Faringe/irrigação sanguínea , Faringe/inervação
6.
Langenbecks Arch Surg ; 393(4): 611-6, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18418627

RESUMO

INTRODUCTION: We report a rare case of solitary fibrous tumour (SFT) of the liver associated with non-islet cell tumour hypoglycaemia (NICTH), which caused a hypoglycaemic coma due to over-production of big-insulin-like growth factor-II. DISCUSSION: Although generally benign, SFTs are better characterised, lately due to Western blot, but less than 40 cases have been reported where the liver is the target organ. In only two benign cases has hypoglycaemia been a feature. CONCLUSION: We report for the first time a demonstrable relationship between benign liver SFT and NICTH.


Assuntos
Coma/etiologia , Hipoglicemia/etiologia , Fator de Crescimento Insulin-Like II/metabolismo , Neoplasias Hepáticas/complicações , Síndromes Paraneoplásicas/etiologia , Precursores de Proteínas/sangue , Tumores Fibrosos Solitários/complicações , Idoso , Coma/sangue , Diagnóstico Diferencial , Hepatectomia , Humanos , Hipoglicemia/sangue , Fígado/patologia , Neoplasias Hepáticas/sangue , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/cirurgia , Masculino , Síndromes Paraneoplásicas/sangue , Tumores Fibrosos Solitários/sangue , Tumores Fibrosos Solitários/diagnóstico por imagem , Tumores Fibrosos Solitários/patologia , Tumores Fibrosos Solitários/cirurgia , Tomografia Computadorizada Espiral
8.
Eur Ann Otorhinolaryngol Head Neck Dis ; 135(3): 171-174, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29402673

RESUMO

GOAL: To analyze the characteristics of adult idiopathic unilateral vocal-fold paralysis. MATERIAL AND METHODS: Retrospective study of diagnostic problems, clinical data and recovery in an inception cohort of 100 adult patients with idiopathic unilateral vocal-fold paralysis (Group A) and comparison with a cohort of 211 patients with isolated non-idiopathic non-traumatic unilateral vocal-fold paralysis (Group B). RESULTS: Diagnostic problems were noted in 24% of cases in Group A: eight patients with concomitant common upper aerodigestive tract infection, five patients with a concomitant condition liable to induce immunodepression and 11 patients in whom a malignant tumor occurred along the path of the ipsilateral vagus and inferior laryngeal nerves or in the ipsilateral paralyzed larynx. There was no recovery of vocal-fold motion beyond 51 months after onset of paralysis. The 5-year actuarial estimate for recovery differed significantly (P<0.0001): 53.2% in Group A versus 17.9% in Group B. In Group A, recovery occurred before the end of the second year following paralysis onset in 93% of cases. On univariate analysis, recovery in Group A was associated with younger age (P=0.0033), shorter time to consultation (P<0.0001), and absence of oncologic history (P<0.028). In case of non-recovery in Group A, malignant tumor along the ipsilateral vagus or inferior laryngeal nerve was found in 17.2% of cases, 81% of which manifesting during the 30 months following the onset of vocal-fold paralysis. CONCLUSION: In non-traumatic vocal-fold paralysis in adult patients, without recovery of vocal-fold motion, a minimum three years' regular follow-up is recommended.


Assuntos
Paralisia das Pregas Vocais/diagnóstico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto Jovem
10.
Eur Ann Otorhinolaryngol Head Neck Dis ; 134(4): 265-267, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28389246

RESUMO

Only about ten articles devoted to operative reports have been published in the medical literature, but this document is essential, both medically and legally, to ensure optimal management of operated patients. In this technical note, based on published studies on this subject, the authors describe the key features of operating reports after otorhinolaryngology head & neck surgery and emphasize the need to write this document during the minutes after the end of the operation, the importance of standardization and its teaching role during surgical training.


Assuntos
Competência Clínica/normas , Otolaringologia/educação , Procedimentos Cirúrgicos Otorrinolaringológicos/educação , Redação/normas , Documentação/normas , Educação Médica Continuada/normas , França , Cabeça/cirurgia , Humanos , Sistemas Computadorizados de Registros Médicos/normas , Pescoço/cirurgia , Otolaringologia/legislação & jurisprudência , Procedimentos Cirúrgicos Otorrinolaringológicos/legislação & jurisprudência , Indicadores de Qualidade em Assistência à Saúde/normas
11.
Eur Ann Otorhinolaryngol Head Neck Dis ; 134(5): 325-331, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28330595

RESUMO

Electrophysiologic hearing tests have been developed since the 1960s to determine hearing thresholds objectively. They are now implemented in newborn hearing screening. While they determine thresholds, interpretation requires subjective pure-tone and speech audiometry to determine the type of hearing loss. Each examination tests a different anatomic region, enabling the auditory system to be explored from the organ of Corti to the auditory cortex. Thus, the various objective audiometric examinations are complementary.


Assuntos
Audiometria de Resposta Evocada , Audiometria de Tons Puros , Potenciais Evocados Auditivos do Tronco Encefálico , Perda Auditiva/diagnóstico , Audiometria de Resposta Evocada/métodos , Audiometria de Tons Puros/métodos , Limiar Auditivo , Perda Auditiva Neurossensorial/diagnóstico , Humanos , Recém-Nascido , Triagem Neonatal/métodos , Prognóstico , Fatores de Tempo
12.
J Hazard Mater ; 335: 75-83, 2017 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-28432972

RESUMO

Uranium ore waste has led to soil contamination that may affect both environmental and soil health. To analyze the risk of metal transfer, metal bioavailability must be estimated by measuring biological parameters. Kinetic studies allow taking into account the dynamic mechanisms of bioavailability, as well as the steady state concentration in organisms necessary to take into account for relevant risk assessment. In this way, this work aims to model the snail accumulation and excretion kinetics of uranium (U), cesium (Cs) and thorium (Th). Results indicate an absence of Cs and Th accumulation showing the low bioavailability of these two elements and a strong uranium accumulation in snails related to the levels of soil contamination. During the depuration phase, most of the uranium ingested was excreted by the snails. After removing the source of uranium by soil remediation, continued snails excretion of accumulated uranium would lead to the return of their initial internal concentration, thus the potential trophic transfer of this hazardous element would stop.


Assuntos
Césio/metabolismo , Caracois Helix/metabolismo , Modelos Biológicos , Poluentes Radioativos do Solo/metabolismo , Tório/metabolismo , Urânio/metabolismo , Animais , Biodegradação Ambiental , Disponibilidade Biológica , Césio/isolamento & purificação , França , Poluentes Radioativos do Solo/isolamento & purificação , Tório/isolamento & purificação , Urânio/isolamento & purificação
13.
Eur Ann Otorhinolaryngol Head Neck Dis ; 134(6): 387-392, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28551009

RESUMO

INTRODUCTION: The medical information provided in medical consultations is exhaustive but poorly assimilated by patients and relatives. Hearing loss seems to be a further obstacle. The main objective of this study was to compare medical information about cochlear implantation delivered in oral and written form ("standard" group) versus oral, written and digital form ("multimedia" group). The secondary objective was to assess hearing loss as a negative factor for understanding medical information, by comparing understanding in patients with unilateral versus bilateral profound hearing loss. PATIENTS AND METHOD: A prospective single-center single-blind study was carried out from September 29, 2015 to June 22, 2016. Twenty-nine CI candidates were included: 11 in the "standard" group, 12 in the "multimedia" group and 6 in the "unilateral hearing loss" group. The primary endpoint was the result on a validated questionnaire (score from 0 to 14) assessing memorization of medical information. Patient satisfaction regarding the information delivered was assessed on a Likert scale. RESULTS: Memorization scores were 4.6±2.7 and 9.7±2.4 respectively for the "standard" and the "multimedia" group (P=0.0006) and 9.05±1.9 for the "unilateral hearing loss" group. Comparison between the "standard" and "unilateral hearing loss" groups showed a significant difference (P=0.01). Satisfaction scores were highest for digital compared to the other forms of medical information delivery. CONCLUSION: This study showed that a digital support improved understanding of medical information by candidates for cochlear implantation and that hearing loss was an obstacle to understanding medical information.


Assuntos
Implante Coclear , Perda Auditiva/cirurgia , Multimídia , Qualidade de Vida , Inquéritos e Questionários , Idoso , Idoso de 80 Anos ou mais , Implante Coclear/métodos , Implantes Cocleares , Feminino , Perda Auditiva/diagnóstico , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Reprodutibilidade dos Testes , Método Simples-Cego , Percepção da Fala , Resultado do Tratamento
14.
Nucleic Acids Res ; 32(Database issue): D560-7, 2004 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-14681481

RESUMO

GermOnline provides information and microarray expression data for genes involved in mitosis and meiosis, gamete formation and germ line development across species. The database has been developed, and is being curated and updated, by life scientists in cooperation with bioinformaticists. Information is contributed through an online form using free text, images and the controlled vocabulary developed by the GeneOntology Consortium. Authors provide up to three references in support of their contribution. The database is governed by an international board of scientists to ensure a standardized data format and the highest quality of GermOnline's information content. Release 2.0 provides exclusive access to microarray expression data from Saccharomyces cerevisiae and Rattus norvegicus, as well as curated information on approximately 700 genes from various organisms. The locus report pages include links to external databases that contain relevant annotation, microarray expression and proteome data. Conversely, the Saccharomyces Genome Database (SGD), S.cerevisiae GeneDB and Swiss-Prot link to the budding yeast section of GermOnline from their respective locus pages. GermOnline, a fully operational prototype subject-oriented knowledgebase designed for community annotation and array data visualization, is accessible at http://www.germonline.org. The target audience includes researchers who work on mitotic cell division, meiosis, gametogenesis, germ line development, human reproductive health and comparative genomics.


Assuntos
Diferenciação Celular/genética , Bases de Dados Genéticas , Perfilação da Expressão Gênica , Células Germinativas/citologia , Células Germinativas/metabolismo , Animais , Biologia Computacional , Genômica , Humanos , Armazenamento e Recuperação da Informação , Internet , Meiose/genética , Mitose/genética , Análise de Sequência com Séries de Oligonucleotídeos , Proteínas/metabolismo , Proteoma , Proteômica , Ratos
15.
Vet Rec ; 159(20): 672-6, 2006 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-17099176

RESUMO

Ninety, seven- to 10-day-old calves were allocated to three groups of 30 and treated daily for seven days with either 100 microg/kg halofuginone hydrobromide or 2.5 mg/kg decoquinate orally or left untreated as controls. The levels of diarrhoea and dehydration were monitored daily for 28 days from the first day of treatment (day 0) and samples of faeces were collected on days 0, 7, 14, 21 and 28, to quantify the excretion of Cryptosporidium parvum oocysts. The calves were weighed on days 3 and 28. The treatments had no effect on the levels of diarrhoea or dehydration, the proportions of diarrhoeic calves or the proportions of calves shedding oocysts. However, unlike decoquinate, halofuginone significantly reduced the excretion of oocysts on day 7 (P<0.0001), and decoquinate increased the average daily weight gain of the calves (P=0.049).


Assuntos
Doenças dos Bovinos/tratamento farmacológico , Coccidiostáticos/uso terapêutico , Criptosporidiose/veterinária , Cryptosporidium parvum/efeitos dos fármacos , Decoquinato/uso terapêutico , Piperidinas/uso terapêutico , Quinazolinonas/uso terapêutico , Animais , Bovinos , Criptosporidiose/tratamento farmacológico , Cryptosporidium parvum/isolamento & purificação , Desidratação/tratamento farmacológico , Desidratação/epidemiologia , Desidratação/parasitologia , Desidratação/veterinária , Diarreia/tratamento farmacológico , Diarreia/epidemiologia , Diarreia/parasitologia , Diarreia/veterinária , Fezes/parasitologia , Feminino , Masculino , Contagem de Ovos de Parasitas/veterinária , Distribuição Aleatória , Resultado do Tratamento , Aumento de Peso
16.
Genetics ; 136(3): 887-902, 1994 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8005443

RESUMO

This study reports the characterization of a cis-acting locus on the Caenorhabditis elegans X chromosome that is crucial for promoting normal levels of crossing over specifically between the X homologs and for ensuring their proper disjunction at meiosis I. The function of this locus is disrupted by the mutation me8, which maps to the extreme left end of the X chromosome within the region previously implicated by studies of X; A translocations and X duplications to contain a meiotic pairing site. Hermaphrodites homozygous for a deletion of the locus (Df/Df) or heterozygous for a deletion and the me8 mutation (me8/Df) exhibit extremely high level of X chromosome nondisjunction at the reductional division; this is correlated with a sharp decrease in crossing over between the X homologs as evidenced both by reductions in genetic map distances and by the presence of achiasmate chromosomes in cytological preparations of oocyte nuclei. Duplications of the wild-type region that are unlinked to the X chromosome cannot complement the recombination and disjunction defects in trans, indicating that this region must be present in cis to the X chromosome to ensure normal levels of crossing over and proper homolog disjunction. me8 homozygotes exhibit an altered distribution of crossovers along the X chromosome that suggests a defect in processivity along the X chromosome of an event that initiates at the chromosome end. Models are discussed in which the cis-acting locus deleted by the Dfs functions as a meiotic pairing center that recruits trans-acting factors onto the chromosomes to nucleate assembly of a crossover-competent complex between the X homologs. This pairing center might function in the process of homolog recognition, or in the initiation of homologous synapsis.


Assuntos
Caenorhabditis elegans/genética , Troca Genética , Cromossomo X , Animais , Mapeamento Cromossômico , Transtornos do Desenvolvimento Sexual/genética , Feminino , Genes de Helmintos , Heterozigoto , Masculino , Meiose/genética , Modelos Genéticos , Mutação , Oócitos/ultraestrutura , Recombinação Genética , Espermatócitos/ultraestrutura , Supressão Genética , Translocação Genética
17.
Genetics ; 124(1): 91-114, 1990 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-2307356

RESUMO

Our previous work demonstrated that mutations in the X-linked gene sdc-1 disrupt both sex determination and dosage compensation in Caenorhabditis elegans XX animals, suggesting that sdc-1 acts at a step that is shared by the sex determination and dosage compensation pathways prior to their divergence. In this report, we extend our understanding of early events in C. elegans sex determination and dosage compensation and the role played by sdc-1 in these processes. First, our analysis of 14 new sdc-1 alleles suggests that the phenotypes resulting from the lack of sdc-1 function are (1) an incompletely penetrant sexual transformation of XX animals toward the male fate, and (2) increased levels of X-linked gene transcripts in XX animals, correlated with XX-specific morphological defects but not significant XX-specific lethality. Further, all alleles exhibit strong maternal rescue for all phenotypes assayed. Second, temperature-shift experiments suggest that sdc-1 acts during the first half of embryogenesis in determining somatic sexual phenotype, long before sexual differentiation actually takes place, and consistent with our previous proposal that sdc-1 acts at an early step in the regulatory hierarchy controlling the choice of sexual fate. Other temperature-shift experiments suggest that sdc-1 may be involved in establishing but not maintaining the XX mode of dosage compensation. Third, a genetic mosaic analysis of sdc-1 produced an unusual result: the genotypic mosaics failed to display the sdc-1 sexual transformation phenotypes. This result suggests several possible interpretations: (1) sdc-1 is expressed immediately, in the one- or two-celled embryo; (2) sdc-1 acts non-cell-autonomously, such that expression of the gene in either the AB or P1 lineage can supply sdc-1(+) function to cells of the other lineage; (3) the X/A ratio is assessed immediately, in the one- or two-celled embryo; or (4) the X/A signal directs the choice of sexual fate in a non-cell-autonomous fashion. Finally, examination of the classes of sexual phenotypes produced in sdc-1 mutant strains suggests that different cells in the organism may not choose their sexual fates independently.


Assuntos
Caenorhabditis/genética , Mecanismo Genético de Compensação de Dose , Genes , Análise para Determinação do Sexo , Alelos , Animais , Caenorhabditis/embriologia , Mapeamento Cromossômico , Feminino , Ligação Genética , Genótipo , Masculino , Mosaicismo/genética , Fenótipo , Supressão Genética , Temperatura , Cromossomo X
18.
Genetics ; 162(1): 113-28, 2002 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12242227

RESUMO

We have implemented a functional genomics strategy to identify genes involved in chromosome morphogenesis and nuclear organization during meiotic prophase in the Caenorhabditis elegans germline. This approach took advantage of a gene-expression survey that used DNA microarray technology to identify genes preferentially expressed in the germline. We defined a subset of 192 germline-enriched genes whose expression profiles were similar to those of previously identified meiosis genes and designed a screen to identify genes for which inhibition by RNA interference (RNAi) elicited defects in function or development of the germline. We obtained strong germline phenotypes for 27% of the genes tested, indicating that this targeted approach greatly enriched for genes that function in the germline. In addition to genes involved in key meiotic prophase events, we identified genes involved in meiotic progression, germline proliferation, and chromosome organization and/or segregation during mitotic growth.


Assuntos
Caenorhabditis elegans/genética , Células Germinativas , RNA/genética , Animais , Sequência de Bases , Primers do DNA , Expressão Gênica , Meiose , Mitose , Morfogênese , Reprodutibilidade dos Testes
19.
Genetics ; 156(2): 617-30, 2000 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11014811

RESUMO

Crossing over and chiasma formation during Caenorhabditis elegans meiosis require msh-5, which encodes a conserved germline-specific MutS family member. msh-5 mutant oocytes lack chiasmata between homologous chromosomes, and crossover frequencies are severely reduced in both oocyte and spermatocyte meiosis. Artificially induced DNA breaks do not bypass the requirement for msh-5, suggesting that msh-5 functions after the initiation step of meiotic recombination. msh-5 mutants are apparently competent to repair breaks induced during meiosis, but accomplish repair in a way that does not lead to crossovers between homologs. These results combine with data from budding yeast to establish a conserved role for Msh5 proteins in promoting the crossover outcome of meiotic recombination events. Apart from the crossover deficit, progression through meiotic prophase is largely unperturbed in msh-5 mutants. Homologous chromosomes are fully aligned at the pachytene stage, and germ cells survive to complete meiosis and gametogenesis with high efficiency. Our demonstration that artificially induced breaks generate crossovers and chiasmata using the normal meiotic recombination machinery suggests (1) that association of breaks with a preinitiation complex is not a prerequisite for entering the meiotic recombination pathway and (2) that the decision for a subset of recombination events to become crossovers is made after the initiation step.


Assuntos
Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/genética , Caenorhabditis elegans/efeitos da radiação , Troca Genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Proteínas de Saccharomyces cerevisiae , Sequência de Aminoácidos , Animais , Animais Geneticamente Modificados , Caenorhabditis elegans/fisiologia , Mapeamento Cromossômico , Cromossomos/genética , Cromossomos/ultraestrutura , Troca Genética/efeitos da radiação , Dano ao DNA , Reparo do DNA , Feminino , Sequências Hélice-Volta-Hélice , Larva , Masculino , Meiose , Dados de Sequência Molecular , Oócitos/fisiologia , Recombinação Genética , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Espermatócitos/fisiologia
20.
Genetics ; 153(3): 1271-83, 1999 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-10545458

RESUMO

Formation of crossovers between homologous chromosomes during Caenorhabditis elegans meiosis requires the him-14 gene. Loss of him-14 function severely reduces crossing over, resulting in lack of chiasmata between homologs and consequent missegregation. Cytological analysis showing that homologs are paired and aligned in him-14 pachytene nuclei, together with temperature-shift experiments showing that him-14 functions during the pachytene stage, indicate that him-14 is not needed to establish pairing or synapsis and likely has a more direct role in crossover formation. him-14 encodes a germline-specific member of the MutS family of DNA mismatch repair (MMR) proteins. him-14 has no apparent role in MMR, but like its Saccharomyces cerevisiae ortholog MSH4, has a specialized role in promoting crossing over during meiosis. Despite this conservation, worms and yeast differ significantly in their reliance on this pathway: whereas worms use this pathway to generate most, if not all, crossovers, yeast still form 30-50% of their normal number of crossovers when this pathway is absent. This differential reliance may reflect differential stability of crossover-competent recombination intermediates, or alternatively, the presence of two different pathways for crossover formation in yeast, only one of which predominates during nematode meiosis. We discuss a model in which HIM-14 promotes crossing over by interfering with Holliday junction branch migration.


Assuntos
Proteínas de Caenorhabditis elegans , Caenorhabditis elegans/citologia , Caenorhabditis elegans/genética , Troca Genética , Proteínas de Ligação a DNA , Proteínas de Helminto/genética , Proteínas de Helminto/metabolismo , Meiose/genética , Proteínas de Saccharomyces cerevisiae , Sequência de Aminoácidos , Animais , Pareamento Incorreto de Bases , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/genética , Núcleo Celular/fisiologia , Sequência Conservada , Reparo do DNA , Feminino , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Proteínas de Helminto/química , Humanos , Dados de Sequência Molecular , Oócitos/fisiologia , Recombinação Genética , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/genética , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos
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