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1.
Electron. j. biotechnol ; 41: 37-47, sept. 2019. tab, graf, ilus
Artigo em Inglês | LILACS | ID: biblio-1087161

RESUMO

Background: Circular RNAs, a novel class in the eukaryotic transcriptome, are characterized by the 3' and 5' ends that are covalently joined in a covalently closed loop without free ends. Circular RNAs are considerably stable molecules and act as microRNA sponges with regulatory potential to the protein-coding genes. Results: Eight circular RNAs were found to be significantly upregulated at anagen skin tissue of cashmere goat compared with their counterparts at telogen. Rich and complex regulatory patterns were revealed among the eight upregulated circular RNAs at anagen and related miRNAs with their potential regulatory genes. The potential regulatory genes of eight upregulated circular RNAs at anagen were involved in several pathways related to the main physiological process of hair follicle, such as histone acetylation and axon. For chi_circ_1926, chi_circ_3541, chi_circ_0483, chi_circ_3196, and chi_circ_2092, overall, the relative expression in secondary hair follicle exhibited highly similar trends with their corresponding host genes during the different stages of the hair follicle cycle. However, the expression trends of chi_circ_0100, chi_circ_2829, and chi_circ_1967 were found to diverge from their corresponding host genes during the different stages of the hair follicle cycle. Conclusions: A total of eighteen circular RNAs were identified and characterized from skin tissue of cashmere goat. The eight upregulated circular RNAs at anagen might have significant roles in the secondary hair follicle of cashmere goat. Our results would provide a novel regulatory layer to elucidate the molecular mechanisms underlying the development of secondary hair follicle and the growth of cashmere fiber in cashmere goat.


Assuntos
Animais , Cabras/genética , Folículo Piloso/crescimento & desenvolvimento , RNA Circular/genética , Pele , Expressão Gênica , Biologia Computacional , MicroRNAs , Células Eucarióticas , Redes Reguladoras de Genes , Transcriptoma , RNA Circular/metabolismo
2.
Electron. j. biotechnol ; 17(5): 224-229, Sept. 2014. ilus, tab
Artigo em Inglês | LILACS | ID: lil-724788

RESUMO

Background Follistatin (FST), a secreted glycoprotein, is intrinsically linked to muscle hypertrophy. To explore the function of duck FST in myoblast proliferation and differentiation, the pEGFP-FST eukaryotic expression vector was constructed and identified. The biological activities of this vector were analyzed by transfecting pEGFP-FST into cultured duck myoblasts using Lipofectamine™ 2000 and subsequently determining the mRNA expression profiles of FST and myostatin (MSTN). Results The duck pEGFP-FST vector was successfully constructed and was confirmed to have high liposome-mediated transfection efficiency in duck myoblasts. Additionally, myoblasts transfected with pEGFP-FST had a higher biological activity. Significantly, the overexpression of FST in these cells significantly inhibited the mRNA expression of MSTN (a target gene that is negatively regulated by FST). Conclusions The duck pEGFP-FST vector has been constructed successfully and exhibits biological activity by promoting myoblast proliferation and differentiation in vitro.


Assuntos
Animais , Transfecção , Mioblastos/metabolismo , Folistatina/metabolismo , Hipertrofia , Doenças Musculares/patologia , Bioensaio , Técnicas In Vitro , RNA Mensageiro , Diferenciação Celular , Proliferação de Células , Patos , Células Eucarióticas/metabolismo , Reação em Cadeia da Polimerase em Tempo Real
3.
Braz. j. microbiol ; 43(2): 517-527, Apr.-June 2012. graf, tab
Artigo em Inglês | LILACS | ID: lil-644466

RESUMO

This study aimed to test different protocols for the extraction of microbial DNA from the coral Mussismilia harttii. Four different commercial kits were tested, three of them based on methods for DNA extraction from soil (FastDNA SPIN Kit for soil, MP Bio, PowerSoil DNA Isolation Kit, MoBio, and ZR Soil Microbe DNA Kit, Zymo Research) and one kit for DNA extraction from plants (UltraClean Plant DNA Isolation Kit, MoBio). Five polyps of the same colony of M. harttii were macerated and aliquots were submitted to DNA extraction by the different kits. After extraction, the DNA was quantified and PCR-DGGE was used to study the molecular fingerprint of Bacteria and Eukarya. Among the four kits tested, the ZR Soil Microbe DNA Kit was the most efficient with respect to the amount of DNA extracted, yielding about three times more DNA than the other kits. Also, we observed a higher number and intensities of DGGE bands for both Bacteria and Eukarya with the same kit. Considering these results, we suggested that the ZR Soil Microbe DNA Kit is the best adapted for the study of the microbial communities of corals.


Assuntos
Biodiversidade , Células Eucarióticas/citologia , DNA Bacteriano , Microbiologia Ambiental , Elapidae/microbiologia , Técnicas In Vitro , Reação em Cadeia da Polimerase/métodos , Microbiologia do Solo , Métodos , Guias como Assunto , Solo
4.
Rev. argent. microbiol ; 44(2): 69-74, jun. 2012. ilus, tab
Artigo em Espanhol | LILACS | ID: lil-657614

RESUMO

En este trabajo se investigó la presencia de determinantes característicos de plásmidos de virulencia en dos aislamientos clínicos de Salmonella Infantis portadores de plásmidos de multirresistencia. Además, se estudió la capacidad de invasión y proliferación en células eucariotas no fagocíticas. Ninguno de los aislamientos de S. Infantis mostró los determinantes genéticos que caracterizan a los plásmidos de virulencia para este género (operón spv). Los ensayos de invasión sobre líneas celulares eucariotas mostraron que los aislamientos de S. Infantis presentan una capacidad de invasión disminuida pero persisten y proliferan en el citoplasma, independientemente de utilizar una línea celular permisiva (HeLa) o no permisiva (NRK) para tal fin. Finalmente, no se observaron indicios microscópicos que podrían hacer sospechar un efecto bactericida de estas líneas celulares sobre los aislamientos estudiados.


Two multidrug-resistant Salmonella Infantis isolates behave like hypo-invasive strains but have high intracellular proliferation. In this work, plasmid-encoded virulence factors in two Salmonella Infantis isolates carrying multiresistance plasmids were investigated. In addition, their invasion and proliferative ability in non-phagocytic cells was studied. None of them showed the typical determinants of virulence plasmids (spv operon). The invasion assays of S. Infantis isolates on eukaryotic cells showed a decreased ability to Invade but they remained and proliferated In the cytoplasm regardless of having used a permissive (HeLa) or non-permissive (NRK) cell line. Finally, there was no microscopic evidence suggesting a bactericidal effect of these eukaryotic cell lines on the Isolates tested.


Assuntos
Animais , Humanos , Ratos , Farmacorresistência Bacteriana Múltipla/genética , Células Eucarióticas/microbiologia , Fatores R/fisiologia , Salmonella/patogenicidade , Sangue/microbiologia , Divisão Celular , Linhagem Celular/microbiologia , Infecção Hospitalar/microbiologia , Fezes/microbiologia , Genes Bacterianos , Marcadores Genéticos , Células HeLa/microbiologia , Rim/citologia , Fatores R/genética , Fatores R/isolamento & purificação , Infecções por Salmonella/microbiologia , Salmonella/efeitos dos fármacos , Salmonella/genética , Salmonella/isolamento & purificação , Virulência/genética
5.
Braz. j. med. biol. res ; 45(2): 97-103, Feb. 2012. ilus, tab
Artigo em Inglês | LILACS | ID: lil-614568

RESUMO

The biological functions of the BC047440 gene highly expressed by hepatocellular carcinoma (HCC) are unknown. The objective of this study was to reconstruct antisense eukaryotic expression vectors of the gene for inhibiting HepG2 cell proliferation and suppressing their xenograft tumorigenicity. The full-length BC047440 cDNA was cloned from human primary HCC by RT-PCR. BC047440 gene fragments were ligated with pMD18-T simple vectors and subsequent pcDNA3.1(+) plasmids to construct the recombinant antisense eukaryotic vector pcDNA3.1(+)BC047440AS. The endogenous BC047440 mRNA abundance in target gene-transfected, vector-transfected and naive HepG2 cells was semiquantitatively analyzed by RT-PCR and cell proliferation was measured by the MTT assay. Cell cycle distribution and apoptosis were profiled by flow cytometry. The in vivo xenograft experiment was performed on nude mice to examine the effects of antisense vector on tumorigenicity. BC047440 cDNA fragments were reversely inserted into pcDNA3.1(+) plasmids. The antisense vector significantly reduced the endogenous BC047440 mRNA abundance by 41 percent in HepG2 cells and inhibited their proliferation in vitro (P < 0.01). More cells were arrested by the antisense vector at the G1 phase in an apoptosis-independent manner (P = 0.014). Additionally, transfection with pcDNA3.1(+)BC047440AS significantly reduced the xenograft tumorigenicity in nude mice. As a novel cell cycle regulator associated with HCC, the BC047440 gene was involved in cell proliferation in vitro and xenograft tumorigenicity in vivo through apoptosis-independent mechanisms.


Assuntos
Animais , Humanos , Camundongos , Carcinoma Hepatocelular/metabolismo , DNA Antissenso/genética , Expressão Gênica , Vetores Genéticos/genética , Proliferação de Células , DNA Antissenso/metabolismo , Células Eucarióticas/metabolismo , Citometria de Fluxo , Vetores Genéticos/metabolismo , /metabolismo , Camundongos Nus , Transplante de Neoplasias , Plasmídeos/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , RNA Mensageiro/análise , Transfecção , Ensaios Antitumorais Modelo de Xenoenxerto
6.
Rev. salud bosque ; 2(1): 25-33, 2012. ilus
Artigo em Espanhol | LILACS | ID: lil-779425

RESUMO

Giardia intestinalis es considerado uno de los eucariotas más antiguos y su poca complejidad representa una valiosa oportunidad para desentrañar los misterios de procesos vitales de eucariotas más complejos. Esta característica única de G. intestinalis y el hecho de que su genoma esté completamente secuenciado y disponible, y que todo su ciclo de vida puede ser reproducido in vitro, hacen de este parásito un modelo ideal para estudiar mecanismos celulares, entre ellos, la muerte celular programada. Desde el punto de vista morfológico y molecular, la apoptosis es uno de los tipos más complejos de muerte celular programada, la cual es un proceso normal durante el desarrollo celular, y tiene un papel esencial en el control de la proliferación celular y en la respuesta a retos inmunológicos o a daños celulares. Recientemente, se ha reportado que en protozoos, entre ellos Giardia, podría ocurrir un tipo de muerte celular programada similar a la apoptosis y los resultados de nuestros laboratorios apoyan esta hipótesis; sin embargo, no se han identificado hasta el momento las moléculas relacionadas con los procesos de apoptosis en estos parásitos. La presente revisión abarca una descripción de la morfología y estructura de las formas de vida de G. intestinalis, de su ciclo biológico, de la parasitosis que causa y de las estrategias quimioterapéuticas para su tratamiento. Asimismo, se hace un repaso de lo que hasta ahora se conoce sobre apoptosis en protozoarios, y específicamente en G. intestinalis, y se describen algunos resultados de nuestro grupo que apoyan la existencia de muerte celular programada en este parásito.


Giardia intestinalis is an early-branching eukaryote and its low complexity represents a valuable opportunity to unravel the mysteries of essential processes in more complex eukaryotes. In addition, the genome of G. intestinalis is completely sequenced and its entire life cycle can be reproduced in vitro. All these characteristics make of Giardia an ideal model for studying cellular mechanisms, such as programmed cell death. Apoptosis is one of the most complex types of programmed cell death and plays an essential role during cell development, cell proliferation and immune response. Recently it has been reported that in Giardia can take place events that resemble apoptosis and although our results support this hypothesis, molecules involved in this process have not yet been identified. This review includes a description of the morphology and structure of G. intestinalis, its life cycle, the disease that causes and the strategies for its treatment. In addition, we review what is known about apoptosis in protozoa, and specifically in G. intestinalis, and describe some results from our group supporting the existence of apoptosis-like programmed cell death in this parasite.


Assuntos
Apoptose , Giardia lamblia/parasitologia , Giardíase/parasitologia , Células Eucarióticas/citologia , Morte Celular/fisiologia , Trofozoítos/parasitologia
7.
An. acad. bras. ciênc ; 83(2): 649-662, June 2011. ilus, tab
Artigo em Inglês | LILACS | ID: lil-589921

RESUMO

Parasitic worms (helminths) within the Phyla Nematoda and Platyhelminthes are responsible for some of the most debilitating and chronic infectious diseases of human and animal populations across the globe. As no subunit vaccine for any parasitic helminth is close to being developed, the frontline strategy for intervention is administration of therapeutic, anthelmintic drugs. Worryingly, and unsurprising due to co-evolutionary mechanisms, many of these worms are developing resistance to the limited compound classes currently being used. This unfortunate reality has led to a renaissance in next generation anthelmintic discovery within both academic and industrial sectors. However, a major bottleneck in this process is the lack of quantitative methods for screening large numbers of small molecules for their effects on the whole organism. Development of methodologies that can objectively and rapidly distinguish helminth viability or phenotype would be an invaluable tool in the anthelmintic discovery pipeline. Towards this end, we describe how several basic techniques currently used to assess single cell eukaryote viability have been successfully applied to parasitic helminths. We additionally demonstrate how some of these methodologies have been adopted for high-throughput use and further modified for assessing worm phenotype. Continued development in this area is aimed at increasing the rate by which novel anthelmintics are identified and subsequently translated into everyday, practical applications.


Vermes parasíticos (helmintos) dos filos Nematoda e Platelmintos são responsáveis por algumas das doenças infecciosas crônicas e mais debilitantes das populações humana e animal em todo o globo. Já que nenhuma vacina está prestes a ser desenvolvida para nenhum parasita helmíntico, a frente estratégica de intervenção é a administração de drogas terapêuticas anti-helmínticas. De maneira preocupante, e não surpreendente devido a mecanismos coevolutivos, muitos destes vermes estão desenvolvendo resistência às limitadas classes de compostos que têm sido usados no momento. Esta infeliz realidade levou a um renascimento na descoberta de uma nova geração de anti-helmínticos tanto no setor acadêmico quanto no industrial. Contudo, um importante gargalo neste processo é a falta de métodos quantitativos para testar um grande número de pequenas moléculas em relação aos efeitos sobre o organismo inteiro. O desenvolvimento de metodologias que possam distinguir objetiva e rapidamente a viabilidade dos helmintos ou o fenótipo seria uma ferramenta valiosa para canalizar a descoberta de anti-helmínticos. Para este fim, descrevemos aqui como muitas técnicas básicas, correntemente usadas para avaliar a viabilidade de células únicas de eucariotos, têm sido aplicadas com sucesso para helmintos parasíticos. Adicionalmente demonstramos como algumas destas metodologias foram adotadas para uso em larga escala e além disso modificadas para avaliar o fenótipo de vermes. O desenvolvimento contínuo nesta área está voltado para aumentar a taxa com que novos anti-helmínticos são identificados e subsequentemente traduzidos em aplicações práticas cotidianas.


Assuntos
Animais , Células Eucarióticas , Helmintos/genética , Fenótipo , Anti-Helmínticos , Descoberta de Drogas/métodos , Helmintos/citologia , Helmintos/efeitos dos fármacos
8.
Univ. med ; 50(3): 284-296, jul.-dic. 2009. tab, ilus
Artigo em Espanhol | LILACS | ID: lil-601527

RESUMO

El estudio del perfil de expresión génica en las células eucariotas se constituye como una herramienta importante en el entendimiento de las huellas moleculares generadas en respuesta a un estímulo farmacológico. A partir de Petiveria alliacea, una de las plantas colombianas con actividad antitumoral, se ha obtenido la fracción FAST 8 7:3, en la cual se han encontrado diferentes compuestos, como el trisulfuro de dibencilo, uno de los componentes antitumorales más potentes reportados para la planta. Esta fracción también posee actividad citotóxica sobre la línea de células tumorales K562 e induce cambios en el perfil de expresión de genes, que podrían estar relacionados de alguna forma con la actividad antitumoral tradicional reportada para esta planta. Esta actividad puede ser ejercida, en parte, por la presencia del trisulfuro de dibencilo y por la actividad de los otros componentes de la fracción. En este contexto, proponemos el uso del ADNc-AFLP como herramienta útil en la tamización del perfil de genes transcritos en las células tumorales y, también, como herramienta útil para el descubrimiento de nuevos fármacos antitumorales...


Abstract Gene expression profile in eukaryotic cells is a very useful tool to understand the molecular footprint responsible for the pharmacological response to a stimulus. In the present study a fraction named FAST 8 (7:3), obtained from Petiveria alliacea, was used as stimulus to track out the gene expression profile on K562 cell line. P. alliacea is a plant that grows in Colombia, and in traditional medicine is used for its anti-tumoral activity. Of the different compounds present in the fraction, dibenzyl trisulfide (DTS), is a compound described by previous reports to have anti-tumoral properties. The fraction exhibits cytotoxic activity over tumor cell line K562 inducing changes in gene expression profile. DTS might be in part responsible for the fraction activity, but the other compounds may also contribute to the biological response. Herein, we propose the use of cDNAAFLP as a useful tool for gene expression profile screening of tumoral cells and in the discovery of new anti-tumoral drugs...


Assuntos
Células Eucarióticas , Preparações Farmacêuticas
9.
J. venom. anim. toxins incl. trop. dis ; 15(1): 79-92, 2009. ilus, graf
Artigo em Inglês | LILACS, VETINDEX | ID: lil-508232

RESUMO

The wolf spider Lycosa singoriensis is a large and venomous spider distributed throughout northwestern China. Like other spider venoms, the wolf spider venom is a chemical cocktail. Its protein content is 0.659 mg protein/mg crude venom as determined by the Lowry method. MALDI-TOF analysis revealed that the venom peptides are highly diverse and may be divided into three groups characterized by three independent molecular ranges: 2,000 to 2,500 Da, 4,800 to 5,500 Da and 7,000 to 8,000 Da, respectively. This molecular distribution differs substantially from those of most spider venoms studied so far. This wolf spider venom has low neurotoxic action on mice, but it can induce hemolysis of human erythrocytes. Furthermore, the venom shows antimicrobial activity against prokaryotic and eukaryotic cells.(AU)


Assuntos
Animais , Venenos de Aranha/farmacologia , Fenômenos Bioquímicos , Células Eucarióticas , Hemólise , Anti-Infecciosos
10.
Genet. mol. biol ; 31(1,suppl): 325-356, 2008. ilus, tab
Artigo em Inglês | LILACS | ID: lil-484617

RESUMO

Actin-encoding cDNAs of Nile tilapia (Oreochromis niloticus) were isolated by RT-PCR using total RNA samples of different tissues and further characterized by nucleotide sequencing and in silico amino acid (aa) sequence analysis. Comparisons among the actin gene sequences of O. niloticus and those of other species evidenced that the isolated genes present a high similarity to other fish and other vertebrate actin genes. The highest nucleotide resemblance was observed between O. niloticus and O. mossambicus a-actin and b-actin genes. Analysis of the predicted aa sequences revealed two distinct types of cytoplasmic actins, one cardiac muscle actin type and one skeletal muscle actin type that were expressed in different tissues of Nile tilapia. The evolutionary relationships between the Nile tilapia actin genes and diverse other organisms is discussed.


Assuntos
Animais , Actinas , DNA Complementar , Peixes/genética , Sequência de Aminoácidos , Células Eucarióticas , Nucleotídeos , Reação em Cadeia da Polimerase Via Transcriptase Reversa
11.
Radiol. bras ; 38(6): 459-462, nov.-dez. 2005. ilus
Artigo em Português | LILACS | ID: lil-421252

RESUMO

A influência de agentes químicos e físicos (em especial a radiação) sobre a freqüência de mutações tem sido amplamente estudada por meio da análise de alterações observadas na Tradescantia, uma planta utilizada como bioindicador dessas alterações. A avaliação das alterações genéticas da Tradescantia pode ser feita tanto pela detecção de mutações somáticas quanto de aberrações cromossômicas induzidas por mutágenos presentes no ar, solo e água. Os resultados apresentados por diversos estudos estimulam o uso da Tradescantia na avaliação dos efeitos das radiações ionizantes. Estudos futuros de mutagenicidade e aberrações cromossômicas também podem ser feitos, por meio da comparação com os efeitos produzidos por outros tipos de radiações, avaliação do efeito da associação da radiação com drogas ou outros agentes químicos, além da biomonitoração de ambientes de alto risco.


The influence of chemical and physical agents (specially radiation) on the frequency of mutations has been widely studied by means of the analysis of changes observed in Tradescantia, a plant used as a bioindicator. The evaluation of these genetic changes may be performed both by detection of somatic mutations or chromosome abnormalities induced by mutagens that are present in the air, soil, or water. The results obtained from several studies support the use of Tradescantia for monitoring the effects of ionizing radiation. Studies of mutagenicity and chromosomal abnormalities may be carried out in future to compare the effects of other types of radiation, evaluation of the effects of the combined use of radiation and drugs or other chemical agents, and to monitor high risk environments.


Assuntos
Células Eucarióticas , Mutação/efeitos da radiação , Radiobiologia , Tradescantia , Tradescantia/efeitos da radiação , Commelinaceae , Radiação Ionizante
12.
An. acad. bras. ciênc ; 77(4): 627-650, Dec. 2005. tab
Artigo em Inglês | LILACS | ID: lil-418014

RESUMO

A presente revisão considerou: (a) os fatores que condicionaram a transição inicial entre não-vida e vida; (b) a estrutura e complexidade genômica em procariotos, eucariotos e organelas; (c) a genômica comparada dos cromossomos humanos; (d) a contribuição brasileira a alguns desses estudos. A compreensão do conflito dialético entre liberdade e organização é fundamental para dar significado aos padrões e processos da evolução orgânica.


Assuntos
Animais , Humanos , Células Eucarióticas , Evolução Molecular , Variação Genética , Genoma , Células Procarióticas , Genômica
13.
Genet. mol. biol ; 28(3,suppl): 634-639, Nov. 2005. tab, graf
Artigo em Inglês | LILACS | ID: lil-440445

RESUMO

Transposable elements (TE) are major components of eukaryotic genomes and involved in cell regulation and organism evolution. We have analyzed 123,889 expressed sequence tags of the Eucalyptus Genome Project database and found 124 sequences representing 76 TE in 9 groups, of which copia, MuDR and FAR1 groups were the most abundant. The low amount of sequences of TE may reflect the high efficiency of repression of these elements, a process that is called TE silencing. Frequency of groups of TE in Eucalyptus libraries which were prepared with different tissues or physiologic conditions from seedlings or adult plants indicated that developing plants experience the expression of a much wider spectrum of TE groups than that seen in adult plants. These are preliminary results that identify the most relevant TE groups involved with Eucalyptus development, which is important for industrial wood production


Assuntos
Elementos de DNA Transponíveis , Eucalyptus/genética , Genoma de Planta , Células Eucarióticas , Etiquetas de Sequências Expressas
14.
P. R. health sci. j ; 24(1): 27-33, mar. 2005.
Artigo em Inglês | LILACS | ID: lil-406523

RESUMO

The post-genomics scientific era has evolved rapidly while achieving advanced understanding of the structure and function of the genes responsible for both the phenotypic characteristics of higher organisms and the pathophysiology of several genetic diseases. Researchers in the fields of oncology and infectious diseases have become more convinced of the great potential of molecular biology approaches to further develop highly specific diagnostic and less toxic therapeutic strategies. During the last two decades, approaches for the specific silencing of essential viral genes and cellular oncogenes were evaluated with optimism for developing directed therapies. However, there were drawbacks in the use of antisense oligonucleotides as a practical mechanism of achieving gene silencing both in vitro and in vivo. Recently, a novel role for post-transcriptional gene silencing mediated by double-stranded RNA (dsRNA) was discovered in the experimental model of C. elegans. This mechanism, termed RNA interference (RNAi) has also been found in other eukaryotes, from plants to mammals, including humans. RNAi is presently being explored both in vitro and in vivo in functional genomics studies and possible therapeutic uses due to its highly specific and physiologic mode of gene silencing. This article focuses on the most current information available regarding the RNAi mechanism and its uses in models of cancer and infectious diseases.


Assuntos
Humanos , Animais , Interferência de RNA/fisiologia , Biologia Molecular , Terapia Genética/métodos , Células Eucarióticas/fisiologia , Inativação Gênica/fisiologia
15.
Braz. j. med. biol. res ; 38(3): 321-334, mar. 2005. ilus, tab
Artigo em Inglês | LILACS | ID: lil-394802

RESUMO

DNA double-strand breaks (DSBs) represent a major threat to the genomic stability of eukaryotic cells. DNA repair mechanisms such as non-homologous end joining (NHEJ) are responsible for the maintenance of eukaryotic genomes. Dysfunction of one or more of the many protein complexes that function in NHEJ can lead to sensitivity to DNA damaging agents, apoptosis, genomic instability, and severe combined immunodeficiency. One protein, Pso2p, was shown to participate in the repair of DSBs induced by DNA inter-strand cross-linking (ICL) agents such as cisplatin, nitrogen mustard or photo-activated bi-functional psoralens. The molecular function of Pso2p in DNA repair is unknown, but yeast and mammalian cell line mutants for PSO2 show the same cellular responses as strains with defects in NHEJ, e.g., sensitivity to ICLs and apoptosis. The Pso2p human homologue Artemis participates in V(D)J recombination. Mutations in Artemis induce a variety of immunological deficiencies, a predisposition to lymphomas, and an increase in chromosomal aberrations. In order to better understand the role of Pso2p in the repair of DSBs generated as repair intermediates of ICLs, an in silico approach was used to characterize the catalytic domain of Pso2p, which led to identification of novel Pso2p homologues in other organisms. Moreover, we found the catalytic core of Pso2p fused to different domains. In plants, a specific ATP-dependent DNA ligase I contains the catalytic core of Pso2p, constituting a new DNA ligase family, which was named LIG6. The possible functions of Pso2p/Artemis/Lig6p in NHEJ and V(D)J recombination and in other cellular metabolic reactions are discussed.


Assuntos
Animais , Humanos , Reparo do DNA/fisiologia , Proteínas de Ligação a DNA/fisiologia , Endodesoxirribonucleases/fisiologia , Células Eucarióticas/química , Instabilidade Genômica , Proteínas Nucleares/fisiologia , Proteínas de Saccharomyces cerevisiae/fisiologia , Proteínas de Ligação a DNA/genética , Endodesoxirribonucleases/genética , Proteínas Nucleares/genética , Proteínas de Saccharomyces cerevisiae/genética
16.
Biol. Res ; 38(2/3): 121-146, 2005. ilus
Artigo em Inglês | LILACS | ID: lil-424717

RESUMO

Ribosome recruitment to eukaryotic mRNAs is generally thought to occur by a scanning mechanism, whereby the 40S ribosomal subunit binds in the vicinity of the 5'cap structure of the mRNA and scans until an AUG codon is encountered in an appropriate sequence context. Study of the picornaviruses allowed the characterization of an alternative mechanism of translation initiation. Picornaviruses can initiate translation via an internal ribosome entry segment (IRES), an RNA structure that directly recruits the 40S ribosomal subunits in a cap and 5' end independent fashion. Since its discovery, the notion of IRESs has extended to a number of different virus families and cellular RNAs. This review summarizes features of both cap-dependent and IRES-dependent mechanisms of translation initiation and discusses the role of cis-acting elements, which include the 5'cap, the 5'-untranslated region (UTR) and the poly(A) tail as well as the possible roles of IRESs as part of a cellular stress response mechanism and in the virus replication cycle.


Assuntos
Humanos , Animais , RNA Mensageiro/análise , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Células Eucarióticas/citologia , Células Eucarióticas/fisiologia , Células Eucarióticas/virologia , Fatores de Iniciação em Eucariotos/análise , Fatores de Iniciação em Eucariotos/biossíntese , Fatores de Iniciação em Eucariotos/genética , Proteínas , RNA Ribossômico/análise , RNA Ribossômico/biossíntese , RNA Ribossômico/síntese química
17.
Braz. j. med. biol. res ; 36(11): 1495-1499, Nov. 2003. ilus
Artigo em Inglês | LILACS | ID: lil-348281

RESUMO

Enterohemolysin produced by Escherichia coli associated with infant diarrhea showed characteristics similar to those of thiol-activated hemolysins produced by Gram-positive bacteria, including inactivation by cholesterol, lytic activity towards eukaryotic cells and thermoinstability. However, enterohemolysin activity was not inactivated by oxidation or by SH group-blocking agents (1 mM HgCl2, 1 mM iodoacetic acid) and the hemolysin (100 æg/ml) was not lethal to mice, in contrast to the lethality of the thiol-activated hemolysin family to animals. Earlier reports showed that intravenous injection of partially purified streptolysin O preparations (0.2 æg) was rapidly lethal to mice. These results suggest that E. coli enterohemolysin is not a thiol-activated hemolysin, despite its ability to bind cholesterol, probably due to the absence of free thiol-group(s) that characterize the active form of the thiol-activated hemolysin molecule.


Assuntos
Animais , Masculino , Camundongos , Toxinas Bacterianas , Eritrócitos , Escherichia coli , Células Eucarióticas , Toxinas Bacterianas , Membrana Celular , Colesterol , Eletroforese em Gel de Poliacrilamida , Hemólise , Ligação Proteica
18.
Genet. mol. res. (Online) ; 2(1): 77-91, Mar. 2003.
Artigo em Inglês | LILACS | ID: lil-417622

RESUMO

The bacteria Escherichia coli has been widely employed in studies of eukaryotic DNA repair genes. Several eukaryotic genes have been cloned by functional complementation of mutant lineages of E. coli. We examined the similarities and differences among bacterial and eukaryotic DNA repair systems. Based on these data, we examined tools used for gene cloning and functional studies of DNA repair in eukaryotes, using this bacterial system as a model


Assuntos
Animais , Células Eucarióticas , Escherichia coli/genética , Reparo do DNA , Sequência de Bases , Clonagem Molecular , Dano ao DNA , Escherichia coli/enzimologia , Genes Bacterianos , Modelos Genéticos
19.
Mem. Inst. Oswaldo Cruz ; 97(4): 517-522, June 2002. ilus
Artigo em Inglês | LILACS | ID: lil-314526

RESUMO

Toxoplasma gondii invades and proliferates in human umbilical vein endothelial cells where it resides in a parasitophorous vacuole. In order to analyze which components of the endothelial cell plasma membrane are internalized and become part of the parasitophorous vacuole membrane, the culture of endothelial cells was labeled with cationized ferritin or UEA I lectin or anti Class I human leukocytte antigen (HLA) before or after infection with T. gondii. The results showed no cationized ferritin and UEA I lectin in any parasitophorous vacuole membrane, however, the Class I HLA molecule labeling was observed in some endocytic vacuoles containing parasite until 1 h of interaction with T. gondii. After 24 h parasite-host cell interaction, the labeling was absent on the vacuolar membrane, but presents only in small vesicles near parasitophorous vacuole. These results suggest the anionic site and fucose residues are excluded at the time of parasitophorous vacuole formation while Class I HLA molecules are present only on a minority of Toxoplasma-containig vacuoles


Assuntos
Animais , Feminino , Camundongos , Endotélio Vascular , Antígenos de Histocompatibilidade Classe I , Toxoplasma , Cordão Umbilical , Células Cultivadas , Endotélio Vascular , Células Eucarióticas , Microscopia Confocal , Microscopia Eletrônica , Cordão Umbilical
20.
Biol. Res ; 35(2): 295-303, 2002. ilus
Artigo em Inglês | LILACS | ID: lil-323352

RESUMO

Nuclear receptors comprise a family of transcription factors that regulate gene expression in a ligand dependent manner. They can activate or repress target genes by binding directly to DNA response elements as homo- or hetero-dimers or by binding to other classes of DNA-bound transcription factors. These activities have been linked to the formation of complexes with molecules that appear to serve as coactivators or corepressors, causing local modification of chromatin structure in order to regulate expression of their target genes. Several members of nuclear receptor family are directly associated with human malignancies including breast cancer, prostate cancer and leukaemia. The pathogenesis of each of these diseases is underpinned by the activities of a member of the superfamily; estrogen receptor-alpha (ER alpha) in breast cancer, androgen receptor (AR) in prostate cancer, and retinoic acid receptor alpha (RAR alpha) in acute promyelocytic leukaemia


Assuntos
Humanos , Receptores Citoplasmáticos e Nucleares , Fatores de Transcrição , Células Eucarióticas , Ligantes , Transcrição Gênica
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