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1.
Biol. Res ; 50: 3, 2017. tab, graf
Artigo em Inglês | LILACS | ID: biblio-838974

RESUMO

Direct tests of the random or non-random distribution of nucleotides on genomes have been devised to test the hypothesis of neutral, nearly-neutral or selective evolution. These tests are based on the direct base distribution and are independent of the functional (coding or non-coding) or structural (repeated or unique sequences) properties of the DNA. The first approach described the longitudinal distribution of bases in tandem repeats under the Bose-Einstein statistics. A huge deviation from randomness was found. A second approach was the study of the base distribution within dinucleotides whose bases were separated by 0, 1, 2... K nucleotides. Again an enormous difference from the random distribution was found with significances out of tables and programs. These test values were periodical and included the 16 dinucleotides. For example a high ¨positive¨ (more observed than expected dinucleotides) value, found in dinucleotides whose bases were separated by (3K + 2) sites, was preceded by two smaller ¨negative¨ (less observed than expected dinucleotides) values, whose bases were separated by (3K) or (3K + 1) sites. We examined mtDNAs, prokaryote genomes and some eukaryote chromosomes and found that the significant non-random interactions and periodicities were present up to 1000 or more sites of base separation and in human chromosome 21 until separations of more than 10 millions sites. Each nucleotide has its own significant value of its distance to neutrality; this yields 16 hierarchical significances. A three dimensional table with the number of sites of separation between the bases and the 16 significances (the third dimension is the dinucleotide, individual or taxon involved) gives directly an evolutionary state of the analyzed genome that can be used to obtain phylogenies. An example is provided.


Assuntos
Humanos , Animais , Filogenia , Sequência de Bases/genética , Genoma , Análise de Sequência de DNA/métodos , Nucleotídeos/genética , Periodicidade , Células Procarióticas/química , Valores de Referência , Algoritmos , DNA Mitocondrial/genética , Distribuição de Qui-Quadrado , Colágeno/genética , HIV-1/genética , Evolução Molecular , Sequências de Repetição em Tandem , Estruturas Cromossômicas , Deriva Genética , Drosophila melanogaster/genética , Epistasia Genética/genética , Nucleotídeos/química
2.
Univ. med ; 53(4): 443-451, oct.-dic. 2012. ilus
Artigo em Espanhol | LILACS | ID: lil-703236

RESUMO

Las alteraciones cromosómicas son una importante causa de muerte en humanos. Sudiagnóstico cuenta con nuevas herramientas que están cada vez más al alcance y permitencorrelacionar los hallazgos de los estudios fetales y placentarios; sin embargo, no entodas las instituciones de salud colombianas se cuenta con tales recursos. Se reportaun caso de trisomía 13, corroborada por hibridación fluorescente in situ (FISH) y seanalizan las manifestaciones histológicas encontradas en la placenta, la cual sí puedeser estudiada de manera rutinaria...


Chromosome alterations are a major cause of death in humans; diagnosis is now aided bynew technology which allows for cross checking on fetal and placental studies. Althoughmany Colombian medical institutions have inadequate access to this technology, weare able to report on a case of Trisomy 13 in which diagnosis was carried out withFluorescence in situ hybridization (FISH) and the histologic manifestations of theplacenta were analyzed following routine procedures...


Assuntos
Placenta/anatomia & histologia , Trissomia/diagnóstico , Estruturas Cromossômicas/classificação
3.
Invest. clín ; 50(2): 173-186, jun. 2009. ilus, tab
Artigo em Espanhol | LILACS | ID: lil-564810

RESUMO

En Colombia el melanoma es la principal causa de muerte por enfermedades dermatológicas (40%) y representa el 1% del total de muertes por cáncer. El rápido incremento en la incidencia del melanoma hace necesaria la realización de estudios que permitan entender mejor los mecanismos implicados en su génesis y progresión. En este estudio se determinaron anomalías cromosómicas en sangre periférica de 30 pacientes con melanoma y en 23 individuos control mediante Citogenética Convencional (Bandeo G), observándose alta incidencia de anomalías numéricas y baja incidencia de rearreglos estructurales recurrentes, siendo las pérdidas cromosómicas las alteraciones prevalentes en todos los estadíos tumorales estudiados. El análisis citogenético de los pacientes mostró que, los cromosomas X, 9 y 17 fueron los más frecuentemente afectados. De las anomalías numéricas las monosomías de los cromosomas X y 17 y la trisomía formada por un cromosoma marcador fueron las más frecuentes, en estadíos tempranos y tardíos de la enfermedad. Deleciones y translocaciones se presentaron como anomalías únicas. En el grupo control ningún tipo de anomalía fue identificada, y se observó bajo porcentaje de fragilidades en comparación con el grupo de pacientes. En comparación con los controles se observó alta frecuencia de anomalías cromosómicas en los pacientes, lo que sugiere la existencia de heterogeneidad y predisposición genética en el desarrollo de la enfermedad, que con investigaciones adicionales deben ser analizadas y validadas como posibles fuentes de marcadores moleculares, útiles para el diagnóstico temprano, tratamiento y seguimiento de la enfermedad.


Among all the skin diseases, melanoma is the main cause of death in Colombia (40%) and it represents 1% of all deaths by cancer. Due to the fast increase in the incidence of melanoma, it is necessary to carry out research on the mechanisms involved in its genesis and progression. This study determined chromosomal anomalies from peripheral blood samples on 30 patients with melanoma and on 23 control subjects using conventional cytogenetics (G Banded), where a high incidence in numerical anomalies and a low incidence in recurrent structural rearrangements were observed. Chromosomic losses were prevalent in all the tumor stages studied. The analysis showed that the chromosomes X, 9 and 17 were mainly affected. Among the numerical anomalies, monosomies in X and 17 chromosomes, as well as trisomies formed by a marker chromosome, were the most common in both early and late stages of the disease. Deletions and chromosomal crossovers appeared to be as isolated anomalies. In the control group no anomaly was identified, and a low percentage of fragility was observed when compared with the patients group. A high frequency in chromosomal anomalies was observed in patients, in contrast with the control subjects. This suggests the existence of heterogeneity and genetic predisposition during the illness development. To further research, these must be analyzed and validated as possible sources of molecular markers, which could be of use for the early diagnosis, treatment and follow up of the disease.


Assuntos
Humanos , Masculino , Adulto , Feminino , Pessoa de Meia-Idade , Idoso de 80 Anos ou mais , Estruturas Cromossômicas , Citogenética/métodos , Melanoma/diagnóstico , Melanoma/tratamento farmacológico , Neoplasias Cutâneas/patologia , Oncologia
4.
Biota neotrop. (Online, Ed. port.) ; 9(2): 257-261, Apr.-June 2009. ilus, tab
Artigo em Inglês | LILACS | ID: lil-529227

RESUMO

The two accessions of B. dura analyzed (DU01 and DU02) are hexaploid (2n = 6x = 54), derived from x = 9. Meiotic abnormalities, such as precocious chromosome migration to the poles, laggards and micronuclei, were recorded in low frequency in both accessions. The few multivalent chromosome association at diakinesis and meiotic stability suggested that hexaploidy probably resulted from chromosome doubling. In DU02, chromosome transfer (cytomixis) among meiocytes, involving part or the entire genome was observed. The implication of these findings for the Brachiaria breeding is discussed.


Os dois acessos de B. dura analisados (DU01 e DU02) são hexaplóides (2n = 6x = 54), derivados de x = 9. Anormalidades meióticas como migração precoce de cromossomos para os polos, cromossomos retardatários e micronúcleos foram observados em baixa frequência em ambos os acessos. A presença de poucas associações cromossômicas em diacinese e a estabilidade meiótica sugere que a hexaploidia provavelmente resultou de duplicação cromossômica. No acesso DU02 observou-se transferência de cromossomos (citomixia) entre meiócitos, envolvendo parte ou todo o genoma. As implicações destes resultados para o melhoramento de Brachiaria são discutidas.


Assuntos
Brachiaria/citologia , Brachiaria/embriologia , Brachiaria/genética , Cromossomos , Cromossomos de Plantas/classificação , Estruturas Cromossômicas/classificação , Mapeamento Físico do Cromossomo
5.
Neotrop. ichthyol ; 7(4): 595-600, 2009. ilus
Artigo em Inglês | LILACS, VETINDEX | ID: lil-536333

RESUMO

Cytogenetic and FISH analyses were performed in 30 Ancistrus cuiabae specimens from a bay near the town of Poconé, in the Pantanal of Mato Grosso, Brazil. The observed diploid number was 2n = 34 chromosomes for both sexes and three distinct katyotypic formulae were found, namely cytotype A (20m, 8sm, 6st, Fundamental Number/FN = 68; 6 males and 11 females), cytotype B (19m, 8sm, 6st, 1a, FN = 67; 8 males and 4 females) and cytotype C (18m, 8sm, 6st, 2a, FN = 66; a single male). NORs's analyses showed that these regions were located in distinct sites on the NOR-bearing chromosome pair, according to cytotypes. Thus, in cytotype A, NORs were located in the terminal region of the short arm of the second metacentric chromosome pair; in cytotype B, they were detected in the short arm of the metacentric chromosome and interstitially on the acrocentric chromosome and, in cytotype C, NORs were observed in the interstitial region of the acrocentric chromosome pair. C-positive heterochromatic bands were adjacent to the rDNA sites in the corresponding chromosomes. Thus, the chromosomal polymorphism of A. cuiabae was probably originated through a pericentric inversion in chromosome pair nº 2 involving the NOR sites, which represents a novelty in the Ancistrini tribe. The results also broaden the knowledge of the chromosomal evolution in Ancistrus, the most derived genus of the Ancistrini tribe.(AU)


Foram analisados, com técnicas convencionais de citogenética e FISH, 30 exemplares da espécie Ancistrus cuiabae da baía Arrombado, próximo a Poconé, Pantanal do Mato Grosso. Foram observadas metáfases com número diploide 2n = 34 cromossomos para ambos os sexos e três fórmulas cariotípicas distintas, aqui denominadas de citótipo A, verificado em 06 machos e 11 fêmeas (20m, 8sm, 6st, Número Fundamental, NF = 68); citótipo B, em 08 machos e 04 fêmeas (19m, 8sm, 6st, 1a, NF = 67) e citótipo C em apenas 01 macho (18m, 8sm, 6st, 2a, NF = 66). As NORs confirmaram os distintos citótipos verificados, além de evidenciar que os cromossomos portadores de rDNA são os que representam o polimorfismo na espécie Ancistrus cuiabae. No citótipo A, as NORs foram verificadas na região terminal do braço curto do segundo par de cromossomos metacêntricos; no citótipo B, foram evidenciadas no segundo par, heteromórfico, no braço curto do cromossomo metacêntrico e intersticial no seu homólogo acrocêntrico; no citótipo C as NORs foram observadas na região intersticial num par de cromossomos acrocêntricos. A análise da heterocromatina constitutiva evidenciou blocos discretos adjacentes ao rDNA no segundo par de cromossomos de ambos os citótipos. Uma provável inversão pericêntrica é a hipótese proposta para a origem deste polimorfismo na espécie Ancistrus cuiabae. Estes resultados ampliam o conhecimento sobre o gênero Ancistrus, o mais derivado da tribo, contribuem para o conhecimento sobre este grupo de peixes e para inferir sobre a evolução cromossômica dos Ancistrini(AU)


Assuntos
Animais , Polimorfismo Genético/genética , Peixes-Gato/genética , Estruturas Cromossômicas
6.
Colomb. med ; 37(1): 61-66, ene.-mar. 2006. ilus, tab
Artigo em Espanhol | LILACS | ID: lil-585772

RESUMO

Objetivos: Demostrar la frecuencia de alteraciones cromosómicas y su relación con la velocidad de crecimiento in vitro en cultivos de células de meningiomas. Los datos obtenidos en estudios previos han enseñado que existe una asociación entre las alteraciones cromosómicas con el riesgo de recurrencia y el estadío del tumor. Materiales y métodos: Se sometieron a cultivo muestras tomadas durante la cirugía de resecciones de meningiomas de cualquier localización, en enfermos del HUV, Clínica Rafael Uribe y clínicas particulares, previo consentimiento firmado de los pacientes o familiares. Se realizaron cultivos celulares, se determinó la velocidad de crecimiento y se obtuvo el cariotipo para definir las alteraciones cromosómicas en cada tumor. Resultados: El 47% de los meningiomas que fue posible estudiar, presentan alteraciones cromosómicas diferentes o además de monosomía del cromosoma 22 que según publicaciones previas se asocian con progresión tumoral, y representan un riesgo de recurrencia mayor a 10%. Conclusiones: Los estudios citogenéticos y la velocidad de crecimiento in vitro de las células tumorales, pueden ser un excelente complemento del resultado quirúrgico, del estudio patológico, que contribuirían a establecer el riesgo de recurrencia y así ayudar a definir el pronóstico para el paciente intervenido.


Objectives: To demonstrate the frequency of chromosomic alterations and their relationship to the growth velocity of in vitro meningioma cells cultures. Data obtained in previous studies have shown that there is a kinship between chromosomic alterations, the risk of recurrence and tumor stage. Materials and methods: Samples taken during meningioma resection surgery from any location were cultured. The samples were obtained from patients at the University Hospital, the Rafael Uribe Clinic and private clinics, previous informed consent either from patients or their relatives. Cell cultures were performed, speed of growth was measured, and the karyotype was obtained in order to define the chromosomic alterations present in each tumor. Results: 47% of the meningiomas studied showed different chromosomic alterations or besides monosomy of the chromosome 22 that according to previous publications are associated to tumoral progression and represent a recurrence risk greater than 10%. Conclusions: The cytogenetic studies and the in vitro cellular growth velocity of the tumoral cells could be excellent complements of the surgical result and the pathology study, contributing to establish the risk of recurrence, so helping to define the patient’s prognosis.


Assuntos
Estruturas Cromossômicas , Cromossomos , Meningioma , Neoplasias , Células Tumorais Cultivadas
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