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1.
WMJ ; 123(2): 113-119, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38718239

RESUMO

INTRODUCTION: The minority tax in academic medicine can be defined as the additional responsibilities placed on underrepresented in medicine (URiM) faculty, staff, and students in the name of diversity. Often this looks like participating in additional diversity committees, recruitment efforts, and mentorship activities. These extra responsibilities often are not recognized, not included in promotions, and take time from other clinical, research, and traditional scholarly responsibilities. OBJECTIVES: There is a significant gap in the literature examining the experiences of URiM-identifying faculty and students in relation to the minority tax. Our goal was to do a quality improvement project to explore this gap through interviewing URiM-identifying faculty and conducting focus groups with URiM-identifying students, with the goal of making recommendations to help reduce the minority tax burdens to this community. METHODS: A scoping literature review on the minority tax burden in academic medicine was used to inform the development of questions to use in focus groups of URiM University of Wisconsin School of Medicine and Public Health (UWSMPH) students and interviews of URiM UWSMPH faculty members. After development of a facilitation guide, we conducted three 1-hour focus groups with 14 students who identified as URiM and did eight 30-minute interviews with faculty who identified as URiM. A codebook was generated using inductive analysis after reviewing transcripts. Coding was performed independently with 2 separate coders in order to ensure inter-coder reliability. RESULTS: Ninety-one percent of students and 62.5% of faculty endorsed experiencing the minority tax at UWSMPH. Faculty also reported increasing feelings of support due to UWSMPH programs that support URiM faculty. Students reported the minority tax being central to their role as URiM students. Both students and faculty reported that the additional burdens of the minority tax took time away from traditional scholarly activities that were essential for promotion (faculty) or residency (students). CONCLUSIONS: The minority tax burden experienced by URiM faculty and students may negatively affect their careers, as they note spending more time on activities that may not be valued for promotion. It is essential to address these burdens in order to achieve equity within the medical institution.


Assuntos
Docentes de Medicina , Grupos Focais , Grupos Minoritários , Faculdades de Medicina , Estudantes de Medicina , Humanos , Wisconsin , Estudantes de Medicina/psicologia , Masculino , Feminino , Impostos , Diversidade Cultural
2.
Radiographics ; 43(5): e220145, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-37104126

RESUMO

Community-based participatory research (CBPR) is defined by the Kellogg Community Health Scholars Program as a collaborative process that equitably involves all partners in the research process and recognizes the unique strengths that each community member brings. The CBPR process begins with a research topic of importance to the community, with the goal of combining knowledge and action with social change to improve community health and eliminate health disparities. CBPR engages and empowers affected communities to collaborate in defining the research question; sharing the study design process; collecting, analyzing, and disseminating the data; and implementing solutions. A CBPR approach in radiology has several potential applications, including removing limitations to high-quality imaging, improving secondary prevention, identifying barriers to technology access, and increasing diversity in the research participation for clinical trials. The authors provide an overview with the definitions of CBPR, explain how to conduct CBPR, and illustrate its applications in radiology. Finally, the challenges of CBPR and useful resources are discussed in detail. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.


Assuntos
Pesquisa Participativa Baseada na Comunidade , Projetos de Pesquisa , Humanos , Pesquisa Participativa Baseada na Comunidade/métodos , Radiologistas
3.
Appl Clin Inform ; 13(1): 10-18, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34986492

RESUMO

OBJECTIVES: This study aimed to develop a virtual electronic health record (EHR) training and optimization program and evaluate the impact of the virtual model on provider and staff burnout and electronic health record (EHR) experience. METHODS: UCHealth created and supported a multidisciplinary EHR optimization and training program, known as the Epic Sprint Program. The Sprint Team conducted dozens of onsite Sprint events over the course of several years prior to the pandemic but transitioned to a fully virtual program and successfully "sprinted" 21 outpatient clinics from May to December 2020. Core program components of group and 1:1 training, workflow analysis, and new or adjusted EHR build were unchanged from the onsite model. Pre- and post-Sprint surveys provided detailed, objective data about EHR usability, EHR proficiency, job satisfaction, and burnout. RESULTS: The EHR Net Promoter Score (NPS), a likelihood to recommend metric, increased by 39 points (-3 pre and 36 post; p < 0.001) for providers and 29 points (8 pre and 37 post; p = 0.001) for staff post-Sprint. Positive provider (NPS = +53) and staff (NPS = +47) NPS scores indicated a high likelihood to recommend the Sprint Program. Post-Sprint surveys also reflect an increase in providers (10%; p = 0.04) and staff (9%; 0.13) who indicated "no burnout" or "did not feel burned out." DISCUSSION: The UCHealth Sprint Team transitioned this comprehensive, enterprise level initiative from an onsite model to a fully virtual EHR training and optimization program during the first few months of the novel coronavirus disease (COVID-19) pandemic. Despite this change in program delivery, survey data clearly demonstrated improved EHR satisfaction, a high likelihood to recommend a sprint to a friend or colleague, and a trend toward burnout reduction in providers and staff. CONCLUSION: Changing an existing on-site EHR optimization program to a purely virtual format can be successful, and this study showed improved provider and staff EHR satisfaction with reduced burnout.


Assuntos
Esgotamento Profissional , COVID-19 , Registros Eletrônicos de Saúde , Humanos , Pacientes Ambulatoriais , SARS-CoV-2
4.
Med. infant ; 17(3): 276-281, Septiembre 2010. ilus
Artigo em Espanhol | LILACS, UNISALUD, BINACIS | ID: biblio-1252761

RESUMO

La Oficina de Comunicación a distancia (OCD) es una estructura creada en 1997 en el Hospital de Pediatría Juan P. Garrahan, con el objetivo de responder consultas a distancia y facilitar el seguimiento de pacientes, con la intención de evitar los traslados innecesarios. Ha dado respuesta a más de 25000 consultas. Actualmente, en el marco del Programa de Comunicación a Distancia (PCD), funcionan 88 OCD distribuidas en 12 de las 23 provincias argentinas. Se presentan resultados sobre una muestra de 148 consultas realizadas al Hospital Garrahan desde 6 provincias, que participaron de un estudio de tipo descriptivo, retrospectivo, cuali-cuantitativo. Éste permitió formular nuevas formas de registro de la tarea y elaborar indicadores cualicuantitativos para evaluar el PCD: consultas, motivo de consulta, tipo de paciente consultado, necesidad de la consulta, duración de la enfermedad al momento de la consulta, derivación sugerida, tiempo de respuesta. Se analizó el número de consultas y las sugerencias de derivación, mostrando las primeras un progresivo y significativo incremento desde la implementación del PCD. Con relación a los motivos de consulta, 84% correspondió a definición de diagnóstico y tratamiento, 16% a motivos de seguimiento e intercurrencias. 62% presentaba patologías crónicas. 95% de los pacientes fueron definidos como complejos. 79% correspondió a consultas definidas como imprescindibles. La derivación fue sugerida en el 54% de las consultas. La mediana del tiempo de respuesta fue de 48 horas. El bajo porcentaje atribuido a "motivos de seguimiento" evidencia la necesidad de profundizar estrategias para promoverlo. El PCD oficializó una modalidad de comunicación que canaliza prácticas anteriormente realizadas a través de vías informales, resignificando la gestión como acto asistencial. Contribuyó a la implementación de metodologías de evaluación conjunta de los indicadores considerados, que contemplan el contexto de la población con la que se trabaja (AU)


In 1997, the Outreach Communication Office (OCO) was created at the Pediatric Hospital Juan P. Garrahan with the aim of responding to consultations from remote places and facilitating follow-up of patients while avoiding unnecessary patient transportations. More than 25,000 consultations have been responded. Currently, within the framework of the Program of Outreach Communication (POC), 88 OCO's are operating distributed over 12 of the 23 Argentine provinces. Here we present the results of a sample of 148 consultations made at the Garrahan Hospital from six provinces that participated in a descriptive, retrospective, qualitative and quantitative study. The study allowed formulation of new methods of task registration and the development of qualitative and quantitative indicators to evaluate the POC: consultations, reason for consultation, type of patient, urgency of the consultation, disease duration until the moment of consultation, suggested referral, and time to response. The number of consultations and suggestions for referral were analyzed showing a progressive and significant increase of the former since the implementation of the POC. Of the reasons for consultation, 84% was related to definition of diagnosis and treatment, 16% to follow-up and intercurrencies. Of all patients, 62% had chronic diseases and 95% were considered complex patients. Of the consultations, 79% were defined as essential and 54% of the patients were referred to specialists. Mean time to response was 48 hours. The low percentage of consultations for "reasons of follow-up" reveals the need to develop strategies to encourage this modality. The POC has officialized a means of communication channeling practices that previously were informal giving a new meaning to the concept management in health care. The POC has contributed to the implementation of methodologies for the assessment of global markers taking into account the context of the population in question (AU)


Assuntos
Humanos , Recém-Nascido , Lactente , Pré-Escolar , Criança , Adolescente , Encaminhamento e Consulta , Telemedicina , Consulta Remota/organização & administração , Consulta Remota/estatística & dados numéricos , Redes Comunitárias/organização & administração , Estudos Retrospectivos
5.
Anticancer Res ; 23(2A): 975-7, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-12820333

RESUMO

INTRODUCTION: Prostatic tumor tissue produces a more complex form of PSA (cPSA) than free PSA (fPSA). For the early detection of prostate cancer, cPSA is supposed to be more sensitive than the ratio of fPSA and tPSA. The aim of the study was to evaluate the diagnostic value of cPSA in the early detection of malignant prostatic tumor. MATERIALS AND METHODS: We evaluated the new cPSA test comparing it with the already routinely used fPSA and tPSA test. The study comprised a total of 100 patients with different urological symptoms attending the Division of Urology, University of Frankfurt, Germany. Biopsy and histological examination were performed in all cases. The histological report was compared with the laboratory results obtained by immunological and electrochemiluminescence methods. RESULTS: Forty-one had a benign tumor of the prostatic gland and 59 had a malignant process diagnosed by histological examination. The cut-off level for cPSA was at 2.3 ng/ml. Within a range of 2.0-4.0 ng/ml tPSA and a cut-off of 2.3 ng/ml for cPSA we found a tumor sensitivity of the test in 92%, proved by the histological report. cPSA allows the detection of a malignant process at an earlier stage than tPSA and even within a "normal-range" of tPSA between 2.0-4.0 ng/ml. A concentration of tPSA between 4.1 and 10 ng/ml represents a grey zone. With measurement of cPSA we achieved, in 71% of our cases, a more specific result than in obtaining the PSA ratio. We did not observe any adverse result in the concentration of cPSA concerning manipulation of the prostatic gland as seen before in the measurement of fPSA. cPSA is much more stable regarding transportation and storage. There is no loss of concentration level observed up to -20 degrees C, whereas fPSA shows a loss of 10%. CONCLUSION: We conclude that the new tumor marker cPSA is more specific in the concentration range of tPSA from 2.0-4.0 ng/ml, as well as in the grey zone between 4.0-10 ng/ml.


Assuntos
Antígeno Prostático Específico/sangue , Neoplasias da Próstata/diagnóstico , Adulto , Idoso , Idoso de 80 Anos ou mais , Diagnóstico Diferencial , Estabilidade de Medicamentos , Humanos , Masculino , Pessoa de Meia-Idade , Antígeno Prostático Específico/classificação , Hiperplasia Prostática/diagnóstico , Valores de Referência
6.
Nucleic Acids Res ; 13(13): 4765-75, 1985 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-4022772

RESUMO

The rabbit genome encodes an opal suppressor tRNA gene. The coding region is strictly conserved between the rabbit gene and the corresponding gene in the human genome. The rabbit opal suppressor gene contains the consensus sequence in the 3' internal control region but like the human and chicken genes, the rabbit 5' internal control region contains two additional nucleotides. The 5' flanking sequences of the rabbit and the human opal suppressor genes contain extensive regions of homology. A subset of these homologies is also present 5' to the chicken opal suppressor gene. Both the rabbit and the human genomes also encode a pseudogene. That of the rabbit lacks the 3' half of the coding region. Neither pseudogene has homologous regions to the 5' flanking regions of the genes. The presence of 5' homologies flanking only the transcribed genes and not the pseudogenes suggests that these regions may be regulatory control elements specifically involved in the expression of the eukaryotic opal suppressor gene. Moreover the strict conservation of coding sequences indicates functional importance for the opal suppressor tRNA genes.


Assuntos
RNA de Transferência/genética , Supressão Genética , Animais , Sequência de Bases , Clonagem Molecular , Coelhos , Transcrição Gênica
7.
J Biol Chem ; 260(4): 2501-8, 1985 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-3156131

RESUMO

A human DNA library, cloned in bacteriophage lambda, was screened with an opal suppressor tRNA probe. Two genes were isolated, subcloned into pBR322, and sequenced. One is a normal opal suppressor tRNA gene 87 nucleotides in length without intervening sequences. It has a TCA anticodon demonstrating that the mature tRNA reads the termination codon UGA. The 5' internal control region for transcription has two extra nucleotides compared to the consensus sequence for eucaryotic tRNA genes, while the 3' internal control region is normal. This gene differs from a previously sequenced chicken opal suppressor serine tRNA gene (Hatfield, D., Dudock, B., and Eden, F. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 4940-4944) only at position 11. The second human gene appears to be a pseudogene truncated near the 3' end, since in the cloverleaf form of the mature tRNA there are three noncomplementary bases in the acceptor stem. The two human genes have a high degree of homology and, excluding the truncated 3' terminus of the pseudogene, differ in only two positions. The flanking sequences of the pseudogene are about 90% homologous to the consensus sequence of the human Alu family of repeated sequences. This gene appears to have been inserted between two adjacent Alu family members.


Assuntos
Códon , RNA Mensageiro , RNA de Transferência/genética , Supressão Genética , Animais , Anticódon , Bacteriófago lambda/genética , Sequência de Bases , Galinhas , DNA , DNA Recombinante/isolamento & purificação , Humanos , Hibridização de Ácido Nucleico
8.
Biochemistry ; 24(1): 229-33, 1985 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-2986675

RESUMO

Structural relationships within a family of long repeated DNA sequences have been determined by molecular cloning of individual family members. About half of the family members are truncated at one end. There is a short, tandemly repeating region flanked by direct repeats associated with truncation. Recombination in a region near the tandemly repeating segment has apparently generated much of the diversity in this family.


Assuntos
Clonagem Molecular , DNA/genética , Sequências Repetitivas de Ácido Nucleico , Animais , Sequência de Bases , Galinhas , Enzimas de Restrição do DNA , Hibridização de Ácido Nucleico , Plasmídeos , Biossíntese de Proteínas
9.
Proc Natl Acad Sci U S A ; 80(16): 4940-4, 1983 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-6308662

RESUMO

A naturally occurring opal suppressor serine tRNA has been purified from chicken liver and used as a probe to isolate the corresponding gene from a library of chicken DNA in bacteriophage lambda. This minor tRNA is encoded by a single-copy gene that is not part of a tRNA gene cluster. DNA sequence analysis of the gene and its flanking DNA segments shows that the gene is encoded in an 87-base-pair segment without intervening sequences and specifies a tRNA that reads the termination codon UGA. This gene has additional nucleotides in the 5' internal promoter region but has a normal 3' internal promoter sequence and the usual termination signal.


Assuntos
Clonagem Molecular , DNA/genética , Genes , Fígado/metabolismo , RNA de Transferência/genética , Supressão Genética , Animais , Bacteriófago lambda/genética , Sequência de Bases , Galinhas , Enzimas de Restrição do DNA , DNA Recombinante/metabolismo , Conformação de Ácido Nucleico , Aminoacil-RNA de Transferência/genética
10.
Nucleic Acids Res ; 9(22): 6001-15, 1981 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-7312632

RESUMO

In the chicken genome, clusters of repeated DNA sequences occur which have alternate arrangements of the component sequence elements. Many of these clustered, repeated sequences are extensively methylated. We have established that both their arrangement and their methylation are invariant regardless of the source of chicken DNA. Comparisons included DNA from sperm, from a series of embryonic stages, from tissues of single adult individuals, and from thirty individual chickens of two strains. These same sequences are found in the DNA of some avian species related to chickens, and there they show the same clustered, methylated form. In related species, some of the arrangements found in chicken DNA are different or missing.


Assuntos
Evolução Biológica , Aves/genética , DNA/genética , Genes , Animais , Embrião de Galinha , Galinhas/genética , Patos/genética , Feminino , Masculino , Metilação , Codorniz/genética , Sequências Repetitivas de Ácido Nucleico , Especificidade da Espécie , Espermatozoides/análise
12.
Biochemistry ; 20(11): 2889-99, 1981 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-6264949

RESUMO

Part of the repeated deoxyribonucleic acid (DNA) in the chicken genome had a clustered organization. The following description of clustered repeated sequences is derived both from analysis of DNA segments cloned in lambda and from hybridization of individual cloned sequences to Southern blots of restricted total DNA. A cluster usually exceeds 20 kbp in length and consists principally, if not entirely, or repetitive DNA. Each cluster contains one cope of several different repeated sequences. The individual sequences occur several hundred times in the genome, but only once per cluster. Many of the clusters contain the same assortment of sequences but in scrambled order. In the genome, those repeated sequences that are elements of clusters occur mainly within the clustered context and are seldom, if ever, found as isolated elements flanked by nonrepeated DNA. These aspects of cluster organization suggest that the clustered sequences undergo limited rearrangement, maintaining the associations within clusters but allowing variability of sequence arrangement from cluster to cluster. The clusters that occupy the cloned DNA segments together represent at least 10% of the repetitive DNA of the chicken.


Assuntos
Cromatina/análise , Clonagem Molecular , DNA Recombinante/metabolismo , Animais , Bacteriófago lambda/genética , Sequência de Bases , Galinhas , DNA , Enzimas de Restrição do DNA , Peso Molecular , Hibridização de Ácido Nucleico
13.
J Biol Chem ; 255(10): 4843-53, 1980 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-6246085

RESUMO

The structural organization of a family of repeated DNA sequences in the chicken genome has been determined by hybridization of a cloned repeated DNA sequence to Southern blots of total DNA. The length of the cloned DNA fragment is 3600 nucleotide pairs. This fragment consists principally, if not entirely, of a single repeated DNA sequence occurring only once within the cloned fragment. In the chicken genome, the family of repeated DNA sequences homologous to the cloned sequence has a limited number of alternative forms. Some of the restriction fragments of total DNA to which the cloned sequence hybridizes correspond to those expected from the location of restriction endonuclease cleavage sites within the cloned sequence. There are also a limited number of other genomic restriction fragments, each present in multiple copies, to which the cloned sequence hybridizes but which do not relate in any obvious way to the length of the cloned sequence. These various restriction fragments differ from one another in that they appear to be present in unequal amounts in total DNA, and many of them do not contain the entire cloned sequence. This study provides some new information about the structure of repeated DNA sequences in the chicken genome. The copies of a repeated DNA sequence may differ from one another both by minor variations in nucleotide sequence (divergence) and in more substantial ways as would be expected to arise from processes such as insertion, deletion, and translocation. In addition to this description of a single cloned repeated DNA sequence from the chicken genome, this paper reports the cloning of more than 100 different restriction fragments of chicken DNA, each of which contains one or more repeated DNA sequences.


Assuntos
Clonagem Molecular , DNA , Genes , Animais , Sequência de Bases , Galinhas , DNA/sangue , Enzimas de Restrição do DNA , DNA Recombinante , Peso Molecular , Hibridização de Ácido Nucleico
14.
J Biol Chem ; 255(10): 4854-63, 1980 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-6246086

RESUMO

The presence of both single copy sequences and repeated DNA sequences with a broad range of repetition frequency is a hallmark of the eukaryotic genome. The advent of recombinant DNA technology has made it possible to isolate cloned DNA fragments that encompass two or more DNA sequences with different repetition frequencies. This provides the first opportunity to investigate the structural relationships in the genome of DNA of the different repetition frequency classes in a thorough and systematic way. A cloned fragment of the chicken genome containing two different repeated DNA sequences has been used for this purpose. By hybridization of radioactive restriction fragments of the cloned DNA to filter-bound restriction fragments of total chicken DNA, it has been determined that the 5.5-kilobase inserted DNA in this clone contains a copy of each of two long, repeated DNA sequence elements with different repetition frequencies. These two repeated DNA sequences have very diverse arrangements in the chicken genome. The results establish that, in addition to the interspersion of single copy and repeated DNA sequences in the chicken genome, repeated DNA sequences with very different structural characteristics can be interspersed with one another. Thus, the chicken genome is a complex network of related sequences in which some members of a family of repeated DNA sequences are associated with other, nonhomologous repeated DNA sequences, while other members of the same family are flanked by single copy DNA.


Assuntos
Clonagem Molecular , DNA , Genes , Animais , Sequência de Bases , Galinhas , DNA/sangue , Enzimas de Restrição do DNA , DNA Recombinante , Escherichia coli/análise , Hibridização de Ácido Nucleico , Plasmídeos
16.
Biochemistry ; 17(24): 5113-21, 1978 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-310314

RESUMO

The extent of reassociation of 3H-labeled repetitive or single copy DNA sequences from the chicken with excess unlabeled DNA from the duck, the Japanese quail, and the ostrich, respectively, was measured by hydroxylapatite chromatography. Chicken repetitive DNA reassociated to an equal or greater extent than chicken single copy DNA with the DNA of each of the other birds. Using an isolated subfraction of chicken repetitive DNA representing those DNA sequences common to the chicken and ostrich genomes, we determined that many repetitive DNA sequences that occur at high repetition frequency in the chicken genome have a much lower repetition frequency in ostrich DNA. The data indicate that there has been a striking change in the number of copies of many repetitive DNA sequences during avian evolution.


Assuntos
DNA/análise , Animais , Sequência de Bases , Evolução Biológica , Aves , Fenômenos Químicos , Físico-Química , Galinhas , Coturnix , Desoxiadenosinas , Patos , Temperatura
17.
Nucleic Acids Res ; 4(5): 1553-67, 1977.
Artigo em Inglês | MEDLINE | ID: mdl-896469

RESUMO

Long and short repetitive sequences of sea urchin DNA were prepared by reassociation of 2000 nucleotide long fragments to Cot 4 and digestion with the single strand specific nuclease S1. The S1 resistant duplexes were separated into long repetitive and short repetitive fractions on Agarose A50. The extent of shared sequences was studied by reassociating a labeled preparation of short repetitive DNA with an excess of unlabeled long repetitive DNA. Less than 10% of the long repetitive DNA preparation was able to reassociate with the short repetitive DNA. Thus the long and short repetitive elements appear to be principally independent sequence classes in sea urchin DNA. Precisely reassociating repetitive DNA was prepared by four successive steps of reassociation and thermal chromatography on hydroxyapatite. This fraction (3% of the genome) was reassociated by itself or with a great excess of total sea urchin DNA. The thermal stability of the products was identical in both cases (Tm=81 degrees C), indicating that precisely repeated sequences do not have many imprecise copies in sea urchin DNA.


Assuntos
DNA , Genes , Animais , Sequência de Bases , DNA Polimerase I , Estabilidade de Medicamentos , Embrião não Mamífero , Feminino , Temperatura Alta , Cinética , Masculino , Peso Molecular , Renaturação de Ácido Nucleico , Ouriços-do-Mar , Espermatozoides
18.
J Mol Evol ; 9(1): 1-23, 1976 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-1018329

RESUMO

The organization of repetitive and single copy DNA sequences in sea urchin DNA has been examined with the single strand specific nuclease S1 from Aspergillus. Conditions and levels of enzyme were established so that single strand DNA was effectively digested while reassociated divergent repetitive duplexes remained enzyme resistant. About 25% of sea urchin DNA reassociates with repetitive kinetics to form S1 resistant duplexes of two distinct size classes derived from long and short repetitive sequences in the sea urchin genome. Fragments 2,000 nucleotides long were reassociated to Cot 20 and subjected to controlled digestion with S1 nuclease. About half of the resistant duplexes (13% of the DNA) are short, with a mode size of about 300 nucleotide pairs. This class exhibits significant sequence divergence, and principally consists of repetitive sequences which were interspersed with single copy sequences. About one-third of the long duplexes (4% of the DNA) are reduced in size after extensive S1 nuclease digestion to about 300 nucleotide pairs. About two-thirds of the long resistant duplexes (8% of the DNA) remains long after extensive SI nuclease digestion. These long reassociated duplexes are precisely base paired. The short duplexes are imprecisely paired with a melting temperature about 9 degrees C below that of precisely paired duplexes of the same length. The relationship between length of repetitive duplex and precision of repetition is confirmed by an independent method and has been observed in the DNA of a number of species over a wide phylogenetic area.


Assuntos
Evolução Biológica , DNA , Ouriços-do-Mar/análise , Animais , Aspergillus/enzimologia , Sequência de Bases , Cromatografia em Gel , DNA/isolamento & purificação , Desoxirribonucleases/metabolismo , Cinética , Peso Molecular
19.
Chromosoma ; 56(4): 309-26, 1976 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-820526

RESUMO

A sensitive search has been made in Drosophila melanogaster DNA for short repetitive sequences interspersed with single copy sequences. Five kinds of measurements all yield the conclusion that there are few short repetitive sequences in this genome: () Comparison of the kinetics of reassociation of short (360 nucleotide) and long (1,830 nucleotide) fragments of DNA; 2) reassociation kinetics of long fragments (2,200 nucleotide) with an excess of short (390 short nucleotide) fragments; 3) measurement of the size of S1 nuclease resistant reassociated repeated sequences; 4) measurement of the hyperchromicity of reassociated repetive fragments as a function of length; 5) direct assay by kinetics of reassociation of the amount of single copy sequence present on 1,200 nucletodie long fragments which also contain repetitive sequences.


Assuntos
DNA/análise , Drosophila melanogaster/química , Animais , Sequência de Bases , Renaturação de Ácido Nucleico , Nucleotídeos
20.
Proc Natl Acad Sci U S A ; 72(7): 2748-52, 1975 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-809769

RESUMO

Extensive studies with pea, tomato, and barley failed to confirm the evidence presented by previous investigators for integration or replication of exogenously applied bacterial DNA in these plants. Labeled DNA of buoyant density in CsCl intermediate between that of high density donor bacterial DNA and of plant DNA was never observed with axenic plants. Intermediate peaks, similar to those used as evidence for recombination by earlier investigators, were observed only when the plants were contaminated with bacteria. Plant DNA prepared by a published procedure [Ledoux, L. & Huart, R. (1969) J. Mol. Biol. 43, 243-262] was found to be contaminated with unidentified impurities. Such DNA was partially protected from the action of DNase and produced aberrant banding patterns in CsCl after shearing. Much of the published evidence for integration of foreign DNA in plants is based upon experiments with plant DNA prepared by this procedure. We conclude that contamination is the likely explanation for what has been interpreted as evidence for integration.


Assuntos
DNA Bacteriano/metabolismo , DNA/metabolismo , Micrococcus/metabolismo , Plantas/metabolismo , Pseudomonas aeruginosa/metabolismo , Rhizobium/metabolismo , Centrifugação com Gradiente de Concentração , Replicação do DNA , Hordeum/metabolismo , Pronase , Especificidade da Espécie , Timidina/metabolismo
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